BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Free Electron Lasers: Past\, Present and Future Challenges DTSTART;VALUE=DATE-TIME:20220705T081500Z DTEND;VALUE=DATE-TIME:20220705T091500Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-817@events.ncbj.gov.pl DESCRIPTION:https://events.ncbj.gov.pl/event/75/contributions/817/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/817/ END:VEVENT BEGIN:VEVENT SUMMARY:Terahertz detectors based on Si CMOS MOSFETs for characterization of broadband and narrow radiation sources DTSTART;VALUE=DATE-TIME:20220708T091000Z DTEND;VALUE=DATE-TIME:20220708T093000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-815@events.ncbj.gov.pl DESCRIPTION:Speakers: Dmytro But (CENTERA Laboratories\, Institute of High Pressure Physics PAS)\nThe so-called "terahertz gap" is gradually being f illed with new compact devices and effective solutions for the detection a nd emission of radiation. In particular\, the development of field-effect -transistors (FET) is starting to play a significant role in this process [1\, 2] and had demonstrated in applications together with pulse free el ectron lasers and gas laser [3\, 4] and fast time-domain system [5]. In t his report\, we present the analysis of different methods which can be app lied for the improvement of detector performance in wide range of frequenc ies. We focus on a standard Si CMOS (complementary metal-oxide-semiconduc tor) process technologies that can be used to produce cost-efficient THz d etectors and sensors which are ready for scaling to sensor lines or arrays . \nWe implement different types of integrated antennas: a patch-type ante nna for the front-side radiation coupling and a slot dipole antenna for th e coupling with a substrate or booster lens. Furthermore\, we extend our r esearch toward the on-chip integrated amplifier. These solutions are not m utually exclusive and can be combined to achieve the best performance.\nAl though the best practical performance is achieved with substrate lens coup led devices\, patch antenna coupling brings the advantage of a strong redu ction in packaging complexity. The disadvantage of patch-antenna coupled d etectors is the relatively small effective area of the antenna which limit s its total efficiency in comparison to a backside-illumination solution w ith the slot antenna. This shortcoming can be improved by an additional di electric lens that is attached to the top of the patch. We simulate and te st the performance of detectors with dielectric lenses of different shapes : a dielectric rod\, hyper-hemisphere\, and aspheric curvature. Several di fferent materials have been employed to fabricate these types of lenses\, like silicon\, sapphire\, or various polymer materials. For example\, the polyethylene hemisphere lens with 4 mm diameter improves the directivity o f the patch antenna by minimum in 1.5 times with an additional advantage o f an improvement in antenna efficiency. \nThe amplifying of the output sig nal – can be realized by using an integrated amplifier implemented on th e same chip. Noise-optimized design and minimized distance between the det ector output and amplifier input results in cost-efficient devices without the deterioration in the signal-to-noise ratio.\nReference: \n[1] Valuši s\, Gintaras\, et al. MDPI Sensors 21.12\, 4092 (2021)\;\n[2] E. Javadi\, et al. MDPI Sensors 21.9 2909 (2021)\;\n[3] Regensburger\, S.\, et al. Opt . expr. 23.16\, 20732-20742 (2015)\;\n[4] But\, D. B.\, et al. J. of App. Phys. 115.16 164514 (2014)\;\n[5] Ikamas\, K.\, et al. Semicond. Sci. Tec hnol.\, 33.12\, 124013 (2018).\n\nhttps://events.ncbj.gov.pl/event/75/cont ributions/815/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/815/ END:VEVENT BEGIN:VEVENT SUMMARY:Nonlinear terahertz spectroscopy on liquid water DTSTART;VALUE=DATE-TIME:20220707T124500Z DTEND;VALUE=DATE-TIME:20220707T133000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-743@events.ncbj.gov.pl DESCRIPTION:Speakers: F. Novelli (Department of Physical Chemistry II\, Ru hr University Bochum\, 44780 Bochum\, DE)\nWater is one of the most studie d and least understood liquids[1]. While several anomalies in the thermody namic\, macroscopic properties of water are well documented[2]\, on the mi croscopic scale this special liquid is characterized by a dynamic\, tetrah edral network of hydrogen bonded (HB) molecules rearranging on the picosec ond timescale[3]. Thus\, terahertz (THz) spectroscopy is uniquely suited t o probe the dynamics of the HB water network. \n\nThe first results detail ing the nonlinear response of water in the THz frequency range are recent\ , and the molecular interpretation is a matter of ongoing discussion. Tcyp kin et al.[4\,5]\, Ghalgaoui et al.[6]\, and Novelli et al.[7–10] all fo und that the third-order nonlinear response of water in the THz range has a similar magnitude\, but proposed different explanations. The transient r esponse of liquid water was assigned to cascaded second-order anharmonicit y of the intramolecular O–H stretching modes[4]\; to the field-induced i rreversible ionization of water molecules[6]\; or to the resonant excitati on of molecular reorientations[8]. \n\nWe performed a series of non-linear experiments at ~1 and 12.3 THz on liquid water at user facilities[7–10] . By comparing results obtained on a static sample and a free-flowing wate r jet at 12.3 THz\, we were able to disentangle the distinct contributions by thermal\, acoustic\, and nonlinear optical effects[9]. Recently\, we s howed that the non-linear response of water at ~1 THz depends weakly on th e temperature of the bulk liquid[10]. Based on these observations\, we sug gest that the THz fields could be reorienting the hydrogen-bonded water mo lecules in the liquid phase\, as originally proposed in ref.[8]. \n\n[1] P . Ball\, Nature. 452 (2008) 291–292. \n[2] P. Gallo\,et al. Pettersson\, Water: A Tale of Two Liquids\, Chem. Rev. 116 (2016) 7463–7500. \n[3] F . Novelli\, B. Guchhait\, M. Havenith\, Materials (Basel). 13 (2020) 1311. \n[4] A. Tcypkin\,et al.\, Phys. Rev. Appl. 15 (2021) 054009.\n[5] A.N. Tc ypkin\, et al.\, Opt. Express. 27 (2019) 10419. \n[6] A. Ghalgaoui\, et al .\, J. Phys. Chem. Lett. 11 (2020) 7717–7722.\n[7] F. Novelli\, et al.\, Appl. Sci. 10 (2020) 5290. \n[8] F. Novelli\, et al.\, J. Phys. Chem. B. 124 (2020) 4989–5001. \n[9] F. Novelli\, et al.\, Phys. Chem. Chem. Phys . 24 (2022) 653–665. \n[10] F. Novelli\, et al.\, Temperature-independen t non-linear terahertz transmission by liquid water\, (2022). https://doi .org/10.48550/arxiv.2206.03998.\n\nhttps://events.ncbj.gov.pl/event/75/con tributions/743/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/743/ END:VEVENT BEGIN:VEVENT SUMMARY:The back – gated AlGaN/GaN HEMT structure for observation of twi sted plasmonic states in terahertz frequency range. DTSTART;VALUE=DATE-TIME:20220706T153500Z DTEND;VALUE=DATE-TIME:20220706T155000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-812@events.ncbj.gov.pl DESCRIPTION:Speakers: Piotr Dróżdż (CENTERA Laboratories\, Institute of High Pressure Physics\, PAS)\nThe Inverse Faraday Effect (IFE) is the app earance of stationary magnetic moments magnetization caused by circulary p olarized ligh. Up to this moment\, IFE has been mostly studied in the magn etic materials. In recent years\, the IFE was predicted in the periodic la ttice of metallic disks or spheres placed in the vicinity of two-dimension al electron liquid and under illumination of the external circularly polar ized light. The radiation causes the DC current loops in the electron liqu id\, thus leading to appearance of static magnetic moments. As a result\, the interaction between metal disks and two-dimensional electron liquid\, the "twisted" plasmonic modes are excited what leads to the appearance of DC circulating current due to rectification. In this work\, we present the basic idea of IFE. The mechanism of the effect is described and the theor etical predictions are presented. We propose GaN/AlGaN as a basic system f or the experimental realization of the IFE. We present GaN/AlGaN HEMT like structure with 2-dimensional electron gas as a channel\, that was made in order to observe the twisted plasmonic modes experimentally. On top of th e structure\, the periodic lattice of metal disks was fabricated with use of electron beam lithography. We present the theoretical predictions and t he technological realization of the structure as well as its basic charact erization. The frequency of the twisted plasmonic modes is expected to be in range of 0.6 - 1.2 THz thus leading to potential applications in terahe rtz physics and technology.\n\nhttps://events.ncbj.gov.pl/event/75/contrib utions/812/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/812/ END:VEVENT BEGIN:VEVENT SUMMARY:Detection of short-pulse terahertz radiation with field-effect tra nsistors DTSTART;VALUE=DATE-TIME:20220707T120000Z DTEND;VALUE=DATE-TIME:20220707T124500Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-813@events.ncbj.gov.pl DESCRIPTION:Speakers: Alvydas Lisauskas (Institute of Applied Electrodynam ics and Telecommunications\, Vilnius University\, Vilnius\, 10257\, Lithua nia\; CENTERA Laboratories\, Institute of High Pressure Physics PAS\, War saw\, 01-142\, Poland)\nDuring the last decade\, field-effect-transistor-b ased terahertz detectors (TeraFETs) have been developed to the competitive technology which enables a variety of new applications in the THz frequen cy range [1]. Among the achieved state-of-the-art performance [2] TeraFETs can also exhibit a strong nonlinear response to intense THz radiation pul ses [3]. We show that the character of nonlinearity can be tuned by gate-t o-source voltage from super-linear to saturation. We support this statemen t by experimental findings on TeraFETs fabricated in CMOS and GaN MMIC tec hnologies using two different systems: a free-electron laser with ~20 ps T Hz pulses and a few THz cycle emission derived from a femtosecond Ti:Sapph ire laser excited photoconductive emitter. Furthermore\, the existence of a superlinear response regime can be supported using large-signal circuit modeling of antenna-coupled devices. This phenomenon can be employed both for THz autocorrelation measurement and to study the build-up time of rect ified signal [4].\n\n[1] G. Valušis\, et al. MDPI Sensors 21.12\, 4092 (2 021). \n[2] E. Javadi\, et al. MDPI Sensors 21.9 2909 (2021). \n[3] K. Ika mas\, I. Nevinskas\, A. Krotkus\, and A. Lisauskas\, Sensors 18\, 3735 (20 18). \n[4] A. Lisauskas et al.\, APL Photonics 3\, 051705 (2018).\n\nhttps ://events.ncbj.gov.pl/event/75/contributions/813/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/813/ END:VEVENT BEGIN:VEVENT SUMMARY:A simple method of evaluating dielectric properties of dielectric layers at sub-terahertz frequencies using tapered dielectric waveguides DTSTART;VALUE=DATE-TIME:20220706T153500Z DTEND;VALUE=DATE-TIME:20220706T155000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-811@events.ncbj.gov.pl DESCRIPTION:Speakers: Valeri Mikhnev (CENTERA Laboratories\, Institute of High Pressure Physics PAS)\nThe accurate knowledge of constitutive paramet ers of dielectric materials is demanded in numerous applications\, from de signing quasi-optical components\, antennas and sensors to nondestructive testing. Terahertz time-domain spectroscopy (THz-TDS) is a recognized tech nique of the broadband material characterization\, but it requires a well- adjusted measurement setup\, special sample holders etc. Alternatively\, t he dielectric properties of materials can be evaluated using such widely u sed sub-THz apparatus as a vector network analyzer with frequency extender s. To this end\, they must be additionally equipped with the dielectric me asurement cells and corresponding software while the free-space measuremen ts require a careful preparatory work similar to THz-TDS systems.\nWe prop ose a simple transmission-mode method of evaluating dielectric properties of thin-sheet materials utilizing a pair of metal-to dielectric waveguide transitions connected to the sub-THz frequency extenders. The dielectric s ample under test is placed in the gap between two open-ended tapered diele ctric waveguides (DW). The dimensions of DW\, length and shape of the tape r have been chosen to ensure the best operation in the near field. The mai n advantage of the tapered DW is an extremely low reflection from the tape r both for outcoming and incident waves that makes the parasitic interfere nce in the measurement area negligible. This allows to use simple formulas for extracting the constitutive parameters of dielectrics. Due to small d imensions of DW\, the illuminated spot of the sample is even smaller than in a free-space setup with focusing lenses.\nThe method was tested using t he frequency extenders V15VNA2-T/R (frequency range up to 75 GHz) and samp les of Teflon\, high-density polyethylene\, high-frequency laminate RT/dur oid 5870\, alumina with the dielectric constant in the range 2.08 to 9.8 a nd thickness of 0.8 mm to 2.4 mm. The measurement error in all cases was a bout 1-3%.\n\nhttps://events.ncbj.gov.pl/event/75/contributions/811/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/811/ END:VEVENT BEGIN:VEVENT SUMMARY:Terahertz spectroscopy of two-dimensional plasmons in grating-gat ed AlGaN/GaN heterostructures DTSTART;VALUE=DATE-TIME:20220706T130000Z DTEND;VALUE=DATE-TIME:20220706T132000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-809@events.ncbj.gov.pl DESCRIPTION:Speakers: Irmantas Kašalynas (THz photonics laboratory\, Cent er for Physical Sciences and Technology\, Vilnius\, Lithuania)\nHigh elect ron mobility and temperature stability of III-nitride heterostructures ser ve as a base for the development of tunable frequency THz emitters. Some T Hz emission results of the 2D plasmons in nitride high electron mobility t ransistor (HEMT) structures have been previously reported\, but they are s till far from commercially viable devices. It is worth noting that the gra phene-based plasmonic metamaterial for THz laser transistors was proposed recently. Nevertheless\, the III-nitride heterostructures as promising pla smonic material were confirmed too by demonstrating possibility of the 2D plasmon excitation up to room temperatures. \nIn this work\, we report on the emission and transmission spectra of the 2D plasmons excited in THz ra nge in grating-gated AlGaN/GaN HEMT structures at the 80 K temperature. Th e plasmonic samples were fabricated by positioning the periodic metal stri pes on top surface of heterostructures over an area of about 2 × 2 mm2. T hree gate-gratings were prepared in the same process on the 10x10 mm2 samp le to minimize fabrication uncertainties and ensure the uniformity of mate rial parameters over the different gratings. The periods of the gratings w ith filling factor of 50 % were selected to be 600 nm\, 800 nm\, and 1000 nm enabling the excitation of fundamental plasmon modes in the frequency r ange of 1 3 THz in wide temperature range. In this work the symmetric 800 nm period gratings were investigated in order to find optimal conditions f or excitation of 2D plasmons under electrical excitation. The ohmic source \, S\, and drain\, D\, contacts to the conductive 2DEG channel were develo ped outside of the grating\, the wave vector of which was oriented perpend icularly to the contacts as described elsewhere. The resonance position an d intensity were found to be related to the grating period and the bias vo ltage applied to the transistor terminals. Moreover\, the Rabi splitting o f 2D plasmon resonance was observed in the emission spectra demonstrating the splitting values to be up to 400 GHz which was considerably larger th an previously reported for the plasmonic samples developed of similar III- nitride heterostructures.\nThis work received funding from the Research Co uncil of Lithuania (Lietuvos mokslo taryba) through project “Hybrid plas monic components for THz range (T-HP)” under Grant No. 01.2.2-LMT-K-718- 03-0096 and was supported by CENTERA Laboratories in frame of the Internat ional Research Agendas program for the Foundation for Polish Sciences co-f inanced by the European Union under the European Regional Development Fund (No. MAB/2018/9).\n\nhttps://events.ncbj.gov.pl/event/75/contributions/80 9/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/809/ END:VEVENT BEGIN:VEVENT SUMMARY:Graphene/hBN - based varactor for novel sub-THz phase shifter. DTSTART;VALUE=DATE-TIME:20220706T153500Z DTEND;VALUE=DATE-TIME:20220706T155000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-807@events.ncbj.gov.pl DESCRIPTION:Speakers: Piotr Dróżdż (CENTERA Laboratories\, Institute of High Pressure Physics\, PAS)\nThe mm-wave and terahertz (THz) frequency r anges are gaining much attention recently due to their high applicability\ , which creates a need for the development of the devices operating in abo vementioned frequency ranges. One among the most important elements of suc h THz devices (e. g. Phase shifters) are varactors (variable capacitors)\, that allow tuning of the system via electrically-induced capacitance shif t. In [1]\, the carbon nanotubes (CNTs) MicroElectroMechanical System (MEM S) varactor is described. \n\nThe device consists of series of etched tre nches with metallized bottoms structuring the bottom electrode. On top of the trenches\, the layer of CNTs is placed\, serving as a top electrode. W hen voltage is applied between the top/bottom electrodes\, the electricall y-formed force causes the nanotube layer to bend towards the bottom electr ode resulting in distance reduction that in final increases the capacitanc e. \n\nHowever\, CNTs are known from changing the capacity by themselves w hen exposed to various environmental conditions like temperature variation \, humidity or illumination. \n\nHere\, we present the new type of the va ractor fabricated upon silicon/SixNy platform with use of carbon-based met amaterials. The design of the structure is inspired by the one reported in [1]. However\, in our approach\, graphene (GR) is used as a top electrode \, since it seems to be more stable and immune against external environmen t conditions. Futher stability improvement is achieved by covering GR with PMMA protective layer. To avoid shorting between GR and bottom electrode an hBN insulating layer was placed under GR. \n\nWe present the character isation measurements of the metamaterial layers used in our device. Finall y\, the electrical characterisation of working device is presented includi ng I - V and C - V characteristics\, which appear to be linear. The tunabi lity of our devices seems to be of the order of few hundred pF/V. \n\n[1] A. A. Generalov et al.\, Nanotechnology 26\, 045201 (2015).\n\nhttps://eve nts.ncbj.gov.pl/event/75/contributions/807/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/807/ END:VEVENT BEGIN:VEVENT SUMMARY:Current status of Chemical Infrared Imaging (CIRI / SOLAIR) beamli ne in Solaris DTSTART;VALUE=DATE-TIME:20220705T155500Z DTEND;VALUE=DATE-TIME:20220705T161500Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-806@events.ncbj.gov.pl DESCRIPTION:Speakers: Tomasz Wróbel (Solaris National Synchrotron Radiati on Centre\, Jagiellonian University\, Czerwone Maki 98\, 30-392 Krakow\, P oland)\nThe Chemical Infrared Imaging (CIRI) /Solaris Advanced InfraRed be amline (SOLAIR) is currently under construction. The large radiation extra ction from a bending magnet will allow to collect a very wide wavelength r ange (0.4 - 500 µm)\, covering the near (NIR)\,_mid (MIR) and the far (FI R) infrared spectral range. The extraction of infrared range of synchrotro n radiation will be achieved using a flat and slotted mirror (M1)\, which will be located inside the dipole chamber located at the bending magnet in the storage ring. \n \nThe presentation will showcase the current status of the project along with the expected IR beam parameters. It will also hi ghlight microscopic techniques (FT-IR\, s-SNOM and PTIR) planned to be use d at the beamline with potential applications.\n\nhttps://events.ncbj.gov. pl/event/75/contributions/806/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/806/ END:VEVENT BEGIN:VEVENT SUMMARY:THz optics – achievements\, challenges\, and prospects DTSTART;VALUE=DATE-TIME:20220705T151500Z DTEND;VALUE=DATE-TIME:20220705T153500Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-805@events.ncbj.gov.pl DESCRIPTION:Speakers: Agnieszka Siemion (Warsaw University of Technology)\ nTerahertz radiation lies at the boundary of two different domains—optic s and electronics. This\, still not fully explored\, area entwines physica l phenomena describing two permeating worlds and interfering laws of optic s and electronics. The fusion of two superposing physical worlds becomes a n enormous challenge in designing optical elements.\nAll types of optical structures have been implemented for the THz waves\, starting from reflect ive optics\, going through refractive and diffractive optics\, and ending on metamaterials. They all require different designing methods\, manufactu ring technologies and materials\, and verification setups. Applicability o f particular types of THz optics also strongly depends on the frequency sp ectrum\, expected efficiency\, working conditions\, complexity\, and price . All of these must be considered when dedicated optical elements are desi gned.\nThis work presents a variety of terahertz optical elements designed by our team. They include a variety of types\, design methods (theoretica l equations\, backward propagation\, iterative algorithms)\, design wavele ngths (from sub-THz band to single terahertz)\, and applications (medical diagnostics\, imaging\, telecommunication). However\, all these elements h ave one thing in common – they are dedicated to particular setups and ap plications\, always ensuring optimized and the best possible performance i n given conditions.\n\nhttps://events.ncbj.gov.pl/event/75/contributions/8 05/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/805/ END:VEVENT BEGIN:VEVENT SUMMARY:FinFET and EdgeFET for THz detectors DTSTART;VALUE=DATE-TIME:20220706T153500Z DTEND;VALUE=DATE-TIME:20220706T155000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-801@events.ncbj.gov.pl DESCRIPTION:Speakers: Grzegorz Cywiński (CENTERA Labs\, Institute of Hig h Pressure Physics PAS )\, Pavlo Sai (CENTERA Labs\, Institute of High Pr essure Physics PAS )\nWe report on the investigations of FinFET and EdeFET AlGaN/GaN field effect transistors as THz detectors. Both devices we fabr icated in the same technological runs on the base of the two-dimensional e lectron gas (2DEG) AlGaN/GaN epitaxial structures and then investigated to wards THz detection. Design of a new FET dubbed EdgeFET is based on two la teral Schottky barrier gates on the sides of 2DEG channel\, which is the s ignificant difference to FinFET. This side gate configuration allowed us t o electrically control the conductivity of the channel by changing its wid th while keeping the carrier density and mobility virtually unchanged. Ele ctrical parameters and photoresponse of EdgeFET will be discussed and comp ared to the standard FinFET device. For understanding the transistor pinch -off process of the EdgeFET channel\, we proposed a gradual channel model. Contrary to FinFET this kind of EdgeFET allowed us to efficiently control the current flow in the 2DEG conduction channel. Moreover\, due to deplet ion\, regions at a certain range of reverse biasing form a nanowire\, whic h is beneficial for the adjustable resonant THz detection. Our studies of DC characteristics and photoresponse in the sub-terahertz frequency confir m the validity of the approach.\n\nhttps://events.ncbj.gov.pl/event/75/con tributions/801/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/801/ END:VEVENT BEGIN:VEVENT SUMMARY:Sub-THz Beamforming DTSTART;VALUE=DATE-TIME:20220707T150500Z DTEND;VALUE=DATE-TIME:20220707T152500Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-802@events.ncbj.gov.pl DESCRIPTION:Speakers: Yevhen Yashchyshyn (Warsaw University of Technology\ ; CENTERA\, Institute of High Pressure Physics\, PAS)\nIntelligent (smart) or adaptive antennas are the most suitable for wireless communication\, e specially for fifth generation and higher communication systems. The key p roperty of intelligent technology is the ability to respond automatically by changing an appropriate radiation pattern. Phase-array based smart ante nnas are used as the main beamforming structure. The development and appli cation of the phase-array in THz frequency range is very problematic. A T IME–MODULATED antenna array (TMAA) can be used as a cheaper alternative. \nTMAA is based on periodical ON/OFF switching of signals received/transm itted from/to each antenna array element\; hence\, continuous wave signals are modulated to pulsed RF signals. The spectrum of a signal after time –modulation is composed of a carrier component and harmonic components ( sidebands). When a TMAA is used to receive a signal at the carrier frequen cy f0\, and the switching frequency fp ≪ f0\, sideband components will a ppear in the receiver. The carrier component can be used for sidelobe redu ction\, while siedebands are suitable for beam–scanning. The advantage o f TMAAs lies in beamforming\, which is achieved with switches instead of p hase–shifters. RF switches based on semiconductors can be low–cost and high power handling components operating in high frequency range. This ad vantage might be a key factor enabling TMAAs to be a low–cost solution a pplicable to future intelligent antenna systems for mm–wave communicatio n. RF switches\, which use a combination of graphene and two-dimensional h igh-density electron gas (2DEG) in the AlGaN/GaN system\, were proposed an d studied. The switches were integrated into the coplanar waveguide\, whic h allows them to be used in any system without the use of\, e.g.\, bonding \, flip-chip and other technologies and avoiding the matching problems. Th e use of such a switch can provide up to 20 MHz of bandwidth in time-modul ated systems\, which is an outstanding result for such systems.\n\nhttps:/ /events.ncbj.gov.pl/event/75/contributions/802/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/802/ END:VEVENT BEGIN:VEVENT SUMMARY:CMOS-based THz detector with on-chip amplifier for imaging applica tions DTSTART;VALUE=DATE-TIME:20220708T093000Z DTEND;VALUE=DATE-TIME:20220708T095000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-799@events.ncbj.gov.pl DESCRIPTION:Speakers: Cezary Kołaciński (CENTERA Laboratory\, Institute of High Pressure Physics PAS\, 01-142 Warsaw\, Poland)\nThe non-ionizing n ature of terahertz radiation together with the ability to penetrate throug h common packaging materials have sparked significant interest in THz non- destructive imaging applications. There is a huge need for low-cost and co mpact THz systems\, which will grow with the further discovery of potentia l THz wave applications. A natural solution to this issue is the usage of mainstream semiconductor technologies\, such as complementary metal-oxide- semiconductor (CMOS) lines. The understanding of device properties and the performance of CMOS-based detectors are constantly improving\, resulting in high sensitivity\, low noise\, and broadband devices. \n\nMentioned det ector improvement stimulates the research aimed at the readout circuits ad dressed to these devices. The integration between CMOS-based detector and on-chip readout electronics seems to be a natural solution. This attitude is optimal from the system performance point of view: the path between det ector output and readout input is minimized. This opens up the way for the possibilities in the field of THz systems development and miniaturization . \n\nIn this study\, we concentrate on a lower range of THz frequencies - the vicinity of 300 GHz. Two different types of integrated antennas have been implemented: a patch-type antenna for the front-side radiation coupli ng and a slot dipole antenna for the coupling with the substrate or booste r lens. Furthermore\, we extend our research toward the on-chip integrated amplifier. These solutions are not mutually exclusive and can be combined to achieve the best performance.\nAlthough the best practical performance is achieved with substrate lens coupled devices\, patch antenna coupling brings the advantage of a strong reduction in packaging complexity. The di sadvantage of patch-antenna coupled detectors is the relatively small effe ctive area of the antenna\, which limits its total efficiency compared to a backside-illumination solution with the slot antenna. This shortcoming c an be improved by an additional dielectric lens attached to the top of the patch. \n\nThe output signal amplifies can be realized by using an integr ated amplifier implemented on the same chip. Noise-optimized design and mi nimized distance between the detector output and amplifier input results i n cost-efficient devices without the deterioration in the SNR (signal-to-n oise ratio). This work uses an integrated circuit based on a differential pair loaded by two resistors to achieve a voltage gain of 20V/V (26dB).\n\ nDescribed above solutions enable to increase of the output signal (and th e practical SNR) by a total factor of approx. ~160 (at 275 GHz of radiatio n frequency for patch antenna detector)\, where the factor x8 is related t o the increased effective area as well as improved efficiency of the anten na and the factor of x20 - due to the amplifier circuit.\n\nhttps://event s.ncbj.gov.pl/event/75/contributions/799/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/799/ END:VEVENT BEGIN:VEVENT SUMMARY:Investigation of electromagnetic coupling between the antenna and split-ring-based metasurface in CMOS technology DTSTART;VALUE=DATE-TIME:20220708T085000Z DTEND;VALUE=DATE-TIME:20220708T091000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-800@events.ncbj.gov.pl DESCRIPTION:Speakers: Alexander Chernyadiev (CENTERA\, Institute of High P ressure Physics PAS)\nPhysics of coupling of resonating structures has bee n investigated for many decades\, yet still new effects are discovered due to the better understanding of the underlying processes and due to the sh ift of the focus from the classical resonators to the quantum objects\, to meta-atoms and to the nanoscale in general. The well-known effect in atom ic physics of the electromagnetically induced transparency was recently de monstrated with optical metamaterials stacked together. It became feasible to realize a near-field sensor based on coupled resonators for detection and spectral analysis of different 2-D materials\, chemical compounds\, or biological materials and structures thanks to the dramatic increase of co upled resonators' sensitivity to the changes of the electromagnetic proper ties of the surrounding medium. Furthermore\, this concept can be efficien tly implemented using the technology platform which is offered by the well -developed mainstream silicon (Si) complementary metal-oxide-semiconductor technology (CMOS). It is commercially available\, reliable\, and due to t he extended metal stack’s functionalities\, providing many possibilities for designing high-frequency components. For example\, 90-nm Si CMOS tech nology served as a platform for designing a terahertz (THz) sensor of huma n body-emitted radiation in a broad range of frequencies 0.1-1.5 THz. In t his paper we report on the investigations of electrodynamic properties of a metasurface-coupled THz antenna with the fundamental resonance frequency of 350 GHz which is implemented in a 180-nm CMOS technology.\nThe structu re under investigation is essentially a THz detector based on a pair of n- type CMOS transistors. The detector is equipped with a differential slot a ntenna with an outer diameter of 450 µm. A single split-ring resonator ha s a size of 65×30 µm with a gap of 10 µm. The numerical simulation of t he electromagnetic properties of coupled resonators was performed by the F inite Element Method in CST Studio Suite. The experimental measurements we re performed with the use of the frequency-domain terahertz platform with the CW THz source based on a photomixer of the TOPTICA's Terascan platform . When both antenna and a split-ring are placed together and their resona nce is tuned to the same frequency\, the electro-magnetic coupling between them results in strong shifting of peak frequencies. One peak shifts towa rds the lower frequencies\, another towards the higher ones. 42% splitting from the initial resonance frequency was recorded. When the antenna is co upled to three split-rings the peaks shift even further from each other. I f the antenna is coupled to a whole system\, a metasurface of split-rings\ , then the 58% splitting from the resonance frequency was recorded. \nSumm arizing this report\, we show that the efficient electromagnetic coupling between the slot antenna and the metasurface of split-ring resonators can be realized in a commercially available 180-nm CMOS technology.\n\nhttps:/ /events.ncbj.gov.pl/event/75/contributions/800/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/800/ END:VEVENT BEGIN:VEVENT SUMMARY:Ultra-wideband graphene-based THz absorbers DTSTART;VALUE=DATE-TIME:20220708T074000Z DTEND;VALUE=DATE-TIME:20220708T080000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-797@events.ncbj.gov.pl DESCRIPTION:Speakers: Dmitri Lioubtchenko (CENTERA Laboratories\, Institut e of High Pressure Physics\, PAS)\nHistorically\, terahertz science and te chnology has been restricted to specialized applications such as radio ast ronomy due to various technological challenges. Hollow rectangular wavegui des are the primary transmission line medium in many terahertz systems due to their mechanical stability\, low electromagnetic losses\, enclosed nat ure\, and compatibility with active circuit elements. Electromagnetic wave devices such as circulators\, couplers and power dividers require that on e or more of their ports be terminated to eliminate unwanted signals and e nsure correct operation. Waveguide terminations are often realized by shor t-circuited waveguide sections that present low reflection and absorb the incident energy due to the presence of an absorbing material inside the wa veguide. We proposed a new kind of ultra-wideband THz absorber which can b e directly integrated into a standard metallic waveguide\, allowing it to be used in conventional THz systems. In_order to analyze the electromagnet ic properties of the absorbing materials in the frequency range from 67 GH z to 500 GHz\, the absorbing material has to be embedded inside a waveguid e. At the sub-millimeter frequencies\, these dimensions get too small to i nsert any absorbing material\; therefore\, we use vacuum filtration to dir ectly deposit the absorber material inside a specialized waveguide cassett e. This cassette can then be integrated with a waveguide system for materi al characterization. The integration method developed here is easily scala ble to different frequency ranges and waveguide geometries and requires on ly standard laboratory equipment and techniques\, making it viable for hig h-volume production. In addition\, by utilizing the same method with preci sion silicon micromachined components\, our approach could be used to deve lop compact\, low-cost THz waveguide absorbers of complex geometry. In thi s study\, graphene augmented inorganic nanofibers (GAIN) were used as wave guide embedded absorbers. The measured insertion loss between 67 GHz to 11 0 GHz is greater than 20 dB and exceeds 40 dB at frequencies above 400 GHz . The reflection coefficient of the samples measured below 200 GHz is in excess of −10 dB\, indicating that much of the incident energy is refle cted by the step change in impedance at the material’s interface at thes e frequencies. The short electrical length of the samples at these frequen cies leads to a relatively low insertion loss\, despite the material’s h igh reflectivity. Above 200 GHz\, the GAIN samples exhibit a reflection coefficient below −10 dB.\n\nhttps://events.ncbj.gov.pl/event/75/contrib utions/797/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/797/ END:VEVENT BEGIN:VEVENT SUMMARY:Technology of graphene and related nanomaterials for THz applicati on DTSTART;VALUE=DATE-TIME:20220706T153500Z DTEND;VALUE=DATE-TIME:20220706T155000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-795@events.ncbj.gov.pl DESCRIPTION:Speakers: Aleksandra Krajewska (CENTERA Laboratories\, Institu te of High Pressure Physics PAS\, Warsaw\, Poland)\nTerahertz (THz) system s and technology have become of large interest over the last 20 years. How ever\, it still needs new and innovative solutions in the field of both ge neration and detection of THz radiation. Despite the fact that scientists in many research centers are constantly working on the production of new T Hz sources and detectors based on semiconductors such as silicon\, it turn out that carbon nanomaterials\, including graphene and van der Waals hete rostructures consisting of layered two-dimensional (2D) materials (h-BN or MoS2) are extremely promising materials for amplification and emission of THz radiation. Also\, combination of 2D materials with “classical” se miconductor materials like GaN and/or GaAs can lead to the production of m aterials with unprecedented THz properties.\nWe demonstrate different meth ods of manufacturing nanodevices based on graphene and other 2D related m aterials. These methods include both the fabrication of 2D heterostructure s from the micrometer scale to large surface area materials. We present st ep-by-step how to combine 2D materials with different materials\, e.g. sem iconductors\, and how to fabricate matrices of THz elements (detectors\, m etasurfaces). \nA comprehensive characterization of the basic electric and THz properties of these materials will be also presented. Preliminary res ults and theoretical analysis indicate the great potential of graphene-bas ed nanostructures for terahertz applications.\n\n**Acknowledgements**\nThe work was supported by the “International Research Agendas” program of the Foundation for Polish Science co-financed by the European Union under the European Regional Development Fund (No. MAB/2018/9) for CENTERA. A.Kr ajewska was supported by the Foundation for Polish Science (FNP).\n\nhttps ://events.ncbj.gov.pl/event/75/contributions/795/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/795/ END:VEVENT BEGIN:VEVENT SUMMARY:Electrically controlled THz plasmon resonances in large surface Al GaN/GaN grating-gate structures DTSTART;VALUE=DATE-TIME:20220707T144500Z DTEND;VALUE=DATE-TIME:20220707T150500Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-796@events.ncbj.gov.pl DESCRIPTION:Speakers: Pavlo Sai (CENTERA Laboratories\, Institute of High Pressure Physics PAS\, ul. Sokołowska 29/37\, 01-142 Warsaw\, Poland)\nWe report on the technology and THz spectroscopy of 2D plasmonic devices bas ed on high density two-dimensional electron plasma in AlGaN/GaN semiconduc tor heterostructures. The devices were fabricated in the geometry of field effect transistor (FET). For the efficient coupling between long waveleng th THz radiation and short wavelength 2D plasma waves\, the special metall ic\, periodic grating-gate couplers were processed\, replacing the usual a ntenna couplers used for sub-micron FET gates. With the developed\, advanc ed technology it was possible to realize large surfaces of the devices (up to 4 mm2) with good gate control and negligible gate leakage currents\, a s proven by magnetooptics and magnetotransport studies [1].\nTHz plasmon r esonances were studied by Fourier Transform Infrared Spectroscopy in a wid e temperature range from 4.2 K to 300 K. We show that the base mode freque ncy of the investigated plasmon resonances lies in THz frequency range bet ween 0.5 THz and 2.0 THz\, depending on the electron plasma density and th e period of the grating-gate coupler. Therefore\, the plasmon frequency ca n be easily electrically tuned by the voltage applied to the grating-gate electrode and\, in this way\, changing the 2D electron density. The electr ical control of the resonance frequency was realized even at room temperat ure. These results are promising for the development of plasmonic devices\ , that arouse great interest as potential resonant THz modulators\, filter s\, detectors\, and emitters with electrically controlled operating freque ncy.\n[1]. P. Sai\, S. O. Potashin\, M. Szoła\, et al.\, Phys. Rev. B 104 \, 045301\, 2021\n\nhttps://events.ncbj.gov.pl/event/75/contributions/796/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/796/ END:VEVENT BEGIN:VEVENT SUMMARY:THz spectroscopy of new materials for high frequency LTCC applicat ions DTSTART;VALUE=DATE-TIME:20220706T153500Z DTEND;VALUE=DATE-TIME:20220706T155000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-790@events.ncbj.gov.pl DESCRIPTION:Speakers: Norbert Pałka (Military University of Technology)\n The rapid development of modern 5G and 6G communication systems is connect ed with a increasing demand for new dielectric substrate materials\, which should provide higher signal transmission speed and miniaturization as we ll as possibility of passive component integration. Requirements for such new materials include a low dielectric constant to minimize signal propaga tion delay\, low dielectric losses for frequency selectivity and reduced e nergy consumption\, and a low sintering temperature to allow the use of mu lti-layer LTCC/ULTCC (low/ultra-high temperature ceramic fired). With the modification of materials with a low dielectric constant\, such as: silica \, borosilicate glasses\, cordierite\, mullite\, forsterite\, diopside\, w illemite\, aluminates\, which have been well known for decades\, less popu lar ceramics have recently appeared\, such as: as borates\, tungstates\, m olybdates\, vanadates\, and phosphates. The use of ceramic-ceramic or glas s–ceramic composites is an effective way to tailor microstructure\, elec tric\, and thermal properties of functional materials for microwave substr ates. \nIn particular\, this approach enables the production of layered st ructures with buried passive electronic components using advanced LTCC tec hnology\, which offers relatively low cost\, flexibility in design and pro duction\, a high degree of miniaturization and integration. Here\, we pres ent terahertz time domain characterization of a few selected materials inc luding their refractive indices and the absorption coefficients. This rese arch was funded by NATIONAL SCIENCE CENTRE\, Poland\, grant number 2019/35 /B/ST5/02674.\n\nhttps://events.ncbj.gov.pl/event/75/contributions/790/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/790/ END:VEVENT BEGIN:VEVENT SUMMARY:Large inverted band-gap in strained three-layer InAs/GaInSb quantu m wells DTSTART;VALUE=DATE-TIME:20220706T153500Z DTEND;VALUE=DATE-TIME:20220706T155000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-789@events.ncbj.gov.pl DESCRIPTION:Speakers: Benoit Jouault (cnrs)\nQuantum spin Hall insulators (QSHIs) based on HgTe and three-layer InAs/GaSb quantum wells (QWs) have c omparable bulk band-gaps of about 10-18 meV. The former however features a band-gap vanishing with temperature\, while the gap in InAs/GaSb QSHIs is rather temperature-independent. We report on the realization of large inv erted band-gap in strained three-layer InAs/GaInSb QWs. By temperature-dep endent magnetotransport measurements of gated Hall bar devices\, we extrac t a gap as high as 45 meV. Combining local and non-local measurements\, we attribute the edge conductivity observed at temperatures up to 40 K to th e edge channels\, of possible topological origin\, with equilibration leng ths of a few micrometers. Our findings pave the way toward manipulating ed ge transport at high temperatures in QW heterostructures.\n\nhttps://event s.ncbj.gov.pl/event/75/contributions/789/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/789/ END:VEVENT BEGIN:VEVENT SUMMARY:Temperature Dependence of Responsivity in Sub-THz band of AlGaN/Ga N and Graphene Transistors DTSTART;VALUE=DATE-TIME:20220706T100500Z DTEND;VALUE=DATE-TIME:20220706T102500Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-788@events.ncbj.gov.pl DESCRIPTION:Speakers: Sergey Rumyantsev (CENTERA Laboratories\, Institute of High Pressure Physics\, )\nThe temperature dependences of photo-respons e in sub-THz regime (0.14 THz) of AlGaN/GaN and graphene transistors were studied at temperatures from 10 to 300 K. Instead of measuring the voltage response using a lock-in amplifier\, the current induced by the incoming sub-THz radiations was measured directly using the semiconductor parameter s analyzer (SPA). This approach allows fast and multiple THz signal detect ion measurements as a function of temperature. \nAlGaN/GaN heterostructure s were grown by the metalorganic vapor phase epitaxy (MOVPE) method in the closed coupled showerhead 3×2 inch Aixtron reactor (Aixtron\, Herzogenra th\, Germany). The epi-structure consisted of a 2 nm GaN cap layer\, 25 nm Al0.24Ga0.76N barrier layer\, a 1.2 nm Al0.66Ga0.37N spacer\, and a thick GaN buffer layer. Growth of all mentioned epilayers was done on the sapph ire substrates. Graphene back gate transistors were fabricated from high- quality single layer graphene encapsulated in h-BN. The device design and high-quality graphene allowed us to achieve the electron mobility of ~3 m2 /Vs at room temperature.\nAt all temperatures\, the current response as a function of the gate voltage was in good agreement with the phenomenologic al expression assuming its proportionality to the first derivative of cond uctivity over the gate voltage. \nWith temperature decrease\, the responsi vity of both kinds of the studied devices increased and saturated at T~100 K. The noise equivalent power continued to decrease with temperature decre ase till the lowest measured temperature of 10K. \nIt was found that the e nhancement in the current responsivity with temperature decrease is much s teeper for graphene than that for GaN-based devices. The temperature depen dence of the response was analyzed based on the model of non-resonant dete ction in filed effect transistors [1]. These results show an advantage of the graphene-based detectors over the GaN-based ones while operating at lo w temperatures.\n\nhttps://events.ncbj.gov.pl/event/75/contributions/788/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/788/ END:VEVENT BEGIN:VEVENT SUMMARY:Cavity-mediated magnon-magnon coupling at 0.3 THz DTSTART;VALUE=DATE-TIME:20220706T074500Z DTEND;VALUE=DATE-TIME:20220706T083000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-787@events.ncbj.gov.pl DESCRIPTION:Speakers: Marcin Bialek (Institute of Physics\, Ecole Polytech nique Fédérale de Lausanne\, Switzerland)\nIn the regime of strong light -matter coupling\, polariton modes are formed that are hybrid light-matter excitations sharing properties of both\, an electrodynamic cavity mode an d a matter mode. Recently\, magnon-polaritons are intensively researched i n ferromagnetic materials in the microwave range\, with potential applicat ions for quantum computing and sensors. In the recent decade\, polaritons were obtained in the THz range with various excitations like\, intersubban d plasmons\, magnetoplasmons in two-dimensional electron gases or vibratio nal modes of molecules. However\, exploring magnetic excitations instead o f dielectric transitions gives an advantage of low damping of spins. We ar e investigating coupling of the antiferromagnetic resonance (AFMR) with TH z cavity modes. Here\, we report on cavity-mediated magnon-magnon coupling in a system consisting of two parallel-plane crystals forming a Fabry-Per ot type cavity. A crystal of yttrium ferrite (YFeO3) is kept at room tempe rature\, while a crystal of hematite (alpha-Fe2O3) is fixed on a copper mi rror placed on a heater. Spin dynamics in both materials are characterized by low damping. We used a monochromatic continuous-wave spectrometer oper ating in the range of 0.2-0.35 THz\, which is based on frequency extenders to a vector network analyser. Reflection spectra measured as a function o f hematite temperature show a series of cavity modes that form avoided cro ssings with the AFMR in the hematite crystal\, frequency of which is risin g with temperature. By measuring temperature-differential spectra\, we rev eal only cavity modes that are coupled to the AFMR in hematite. That is be cause the AFMR in the YFeO3 crystal does not depend on temperature of the hematite crystal\, therefore modes coupled to YFeO3 do not show up in temp erature-differential spectra. Contrary\, differential spectra to external magnetic field reveal only cavity modes coupled to the AFMR in YFeO3 that has a frequency of about 300 GHz. Since the magnetic field is applied in a direction that does not change the AFMR in hematite\, magnetic field-diff erential spectra do not show the modes coupled to the AFMR in hematite. Di fferential to a gap between the two crystals reveals the cavity modes. Und er certain gap between the crystals\, we can observe cavity modes that are strongly coupled to the AFMR in both crystals at the same time\, which su ggest that magnons in both crystal are coupled via a cavity mode.\n\nhttps ://events.ncbj.gov.pl/event/75/contributions/787/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/787/ END:VEVENT BEGIN:VEVENT SUMMARY:Tunable CNT Surfaces for THz Wave Applications DTSTART;VALUE=DATE-TIME:20220706T153500Z DTEND;VALUE=DATE-TIME:20220706T155000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-777@events.ncbj.gov.pl DESCRIPTION:Speakers: Aleksandra Przewłoka (CENTERA Laboratories\, Instit ute of High Pressure Physics\, PAS )\, Dmitri Lioubtchenko (CENTERA Labora tories\, Institute of High Pressure Physics\, PAS )\nThe research and deve lopment in the frequency region of 0.1-1.0 THz is extremely significant fo r the wide range of applications\, such as telecommunication and imaging s ystems\, material spectroscopy\, medical imaging and treatments\, etc. Des pite the problems in technology and high prices for basic components (phas e shifters\, directional couplers\, etc.)\, the THz systems offer higher d ate rates for telecommunication\, high spatial resolution in the visualiza tion of objects\, small size of antennas and other elements. The state-of- the-art of the THz devices reveals serious problems with radiation sources with continuous wave semiconductor-based source\, electronically tunable phase shifters\, etc.\nCarbon nanotubes (CNT) offer unique properties due to their natural small dimensions and outstanding electrical properties. T heir tunability properties makes them very attractive in application to th e THz system. Integration of CNTs with the dielectric rod waveguide (DRW) technology transferred from cellulose membranes onto other substrates (sap phire DRW\, optical glass\, polished silicon) by direct dry transfer enabl es a novel technology platform for tunable THz systems.\nPhase shifter can be developed by introducing the optically controlled varactor to the DRW. The phase change of 10-20 deg with almost negligible change in attenuatio n less than 0.1 dB can be achieved in the frequency range of 75-500 GHz. B esides\, DRWs have no cut-off frequency enabling broad band operation.\nTh e effect of the dielectric constant tuning of single-walled carbon nanotub es under light illumination is observed in the very wide frequency range o f 0.1–1 THz. The optical absorption spectrum is not uniform and it consi sts of several absorption peaks related to electron transitions. Therefore \, the change of capacity and resistance under different light wavelength illumination is different at different wavelengths.\nThe losses are attrib uted to the electromagnetic absorption by the CNT layers with differences stemming from variations in nanotube densities and total lengths of the tr ansferred samples on the DRWs. The increased absorbance at lower frequenci es has also been previously observed for CNTs.\nCarbon based nanomaterials are perspective materials for very wide applications in millimeter wave a nd THz frequency range. Phase shifter based on DRW loaded with CNT layer i s a perspective candidate for ultra-wide band device application. The ultr a-wide band optically controlled CNT-based phase shifter can enable THz be am steering.\n\nhttps://events.ncbj.gov.pl/event/75/contributions/777/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/777/ END:VEVENT BEGIN:VEVENT SUMMARY:THz magnetism - terra incognita beyond the conventional approximat ions DTSTART;VALUE=DATE-TIME:20220707T070000Z DTEND;VALUE=DATE-TIME:20220707T074500Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-774@events.ncbj.gov.pl DESCRIPTION:Speakers: Alexey Kimel (Radboud University)\nAntiferromagnets are ideal candidates to reach THz landmark in data storage with no additio nal energy costs. However\, the lack of a net magnetization in these mater ials requires exceedingly high magnetic fields to manipulate their spins\, hindering not only applications\, but even fundamental studies on writing bits on antiferromagnets. Here we propose an approach to empower THz cont rol of antiferromagnetic order_by pushing antiferromagnet out of equilibri um through generation of coherent magnonic state. We will show that an ant iferromagnet out of equilibrium is practically a different material. Gener ation of coherent magnonic states in antiferromagnets substantially modifi es the susceptibility of antiferromagnetic spins to THz magnetic fields an d facilitates energy transfer between otherwise noninteracting phononic an d magnonic modes [1\,2]. In this case\, the generated impact on spins goes far beyond trivial superposition of excitations and can facilitate concep tually new ways for controlling antiferromagnetism. The proposed theoretic al description suggests that spin dynamics in antiferromagnets is intrinsi cally non-linear and once coherent magnonic state is induced\, additional channels of energy transfer between otherwise orthogonal modes open up. \n [1] E. A. Mashkovich\, K. Grishunin\, R. Dubrovin\, R. V. Pisarev\, A. K. Zvezdin and A. V. Kimel\, THz light driven coupling of antiferromagnetic s pins to lattice\, Science 374\, 1608-1611 (2021). \n[2] Th. Blank et al (i n preparation)\n\nhttps://events.ncbj.gov.pl/event/75/contributions/774/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/774/ END:VEVENT BEGIN:VEVENT SUMMARY:Superradiant terahertz facilities for high field Terahertz Science – the first 2 decades DTSTART;VALUE=DATE-TIME:20220705T133000Z DTEND;VALUE=DATE-TIME:20220705T141500Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-783@events.ncbj.gov.pl DESCRIPTION:Speakers: Michael Gensch (DLR Institut für Optische Sensorsys teme / TU Berlin)\nUltrashort flashes of THz light with low photon energie s of a few meV\, but strong electric or magnetic field transients have in the past two decades been increasingly employed to prepare various fascin ating nonequilibrium states in matter. Superradiant Terahertz radiation fr om linear accelerators\, first demonstrated in 2001 at Jefferson lab [1]\, is the working principle of a new class of sources for high-field THz p ulses which turned out to be ideally suited to perform experiments of this type. Over the past 20 years several superradiant THz facilities have bee n commissioned (see e.g. [2]) from facilities operating parasitically at t he linac of soft X-ray free electron lasers [3\,4] to dedicated compact fa cilities operating at high repetition rates based on superconducting linac technology [5]. This talk will give an overview of these developments and will discuss some of the scientific highlight experiments. An outlook int o proposed next generation facilities is given which will include faciliti es at hard X-ray free electron lasers [6\,7] and dedicated multi-user faci lities. In addition\, emerging new experimental opportunities are presente d.\n\n[1] L. Carr et al\, High-power terahertz radiation from relativistic electrons\, Nature 420\, 153 (2001).\n[2] M. Gensch et al\, SUPER-RADIANT LINAC-BASED THz SOURCES IN 2013\, proceed. Of FEL 2013\, New York\, WEIBN O01 (2013).\n[3] A. Perucchi et al\, The TeraFERMI terahertz source at the seeded FERMI free-electron-laser facility\, Rev. Sci. Instr. 84\, 022702 (2013).\n[4] M. Gensch et al\, New infrared undulator beamline at FLASH\, Infrared Phys. Technol. 51\, 423 (2008).\n[5] B. Green et al\, High-field high-repetition-rate sources for the coherent THz control of matter\, Sci. Rep. 6\, 22256 (2016).\n[6] T. Tanikawa et al\, Volt-per-Ångstrom terahe rtz fields from X-ray free-electron lasers\, J. Synch. Rad. 27\, 796 (2020 ).\n[7] Z. Zhang et al\, A high-power\, high-repetition-rate THz source fo r pump–probe experiments at Linac Coherent Light Source II\, J. Synch. R ad. 27\, 890 (2020).\n\nhttps://events.ncbj.gov.pl/event/75/contributions/ 783/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/783/ END:VEVENT BEGIN:VEVENT SUMMARY:Amplification of THz Radiation by Strong Interaction of Drifting E lectrons with Plasmons in Graphene and GaN DTSTART;VALUE=DATE-TIME:20220707T094500Z DTEND;VALUE=DATE-TIME:20220707T103000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-785@events.ncbj.gov.pl DESCRIPTION:Speakers: Wojciech Knap (CENTERA Laboratories\, Institute of H igh Pressure Physics PAS\, Warsaw)\nMore than 40 years ago\, a new directi on in physics opened up with the arrival of plasma-wave electronics. The p ossibility that the plasma waves could propagate faster than electrons fas cinated all. Therefore\, it was initially expected that plasmonic devices\ , including detectors and generators of electromagnetic radiation\, would be able to work effectively in the very high frequencies - terahertz (THz) range\, inaccessible to standard electronic devices. However\, numerous e xperimental attempts to realize the amplifiers or emitters failed: the int ensity of radiation turned out to be too small\, plasma resonances too bro ad\, or devices operated only at cryogenic temperatures. \nWe demonstrate – for the first time- experimentally strong interaction of resonant pla smons in Graphene with drifting electrons leading to THz radiation amplifi cation with a gain going up to 9%. The results are interpreted using a dis sipative plasmonics crystal model\, which captures some trends and basic p hysics of the amplification phenomena but is far from being completed [1] .\nWe will present challenges of both experimental and theoretical researc h on the strong plasmons-drifting electrons- THz light interaction in Dira c matter - that were recently (2022) recognized as an important research direction by EU commission - awarding ERC -Advanced grant –“TERAPLAS M” that will be realized by CENTERA laboratory – UNIPRESS-PAN in cons ortium with CEZAMAT – Technical University of Warsaw and in collaboratio n with teams from Japan France Germany\n\n[1] Boubanga-Tombet S\, Knap W\, Yadav D\, Satou A\, But DB\, Popov VV\, Gorbenko IV\, Kachorovskii V\, Ot suji T: Room-Temperature Amplification of THz Radiation by Grating-Gate Gr aphene Structures. Phys Rev X 2020\; 10(( 3): 031004. [DOI: 10.1103/PhysRe vX.10.031004]\n\nhttps://events.ncbj.gov.pl/event/75/contributions/785/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/785/ END:VEVENT BEGIN:VEVENT SUMMARY:PolFEL project: towards the construction of the Polish THz/IR/VUV Free Electron Laser DTSTART;VALUE=DATE-TIME:20220705T141500Z DTEND;VALUE=DATE-TIME:20220705T143500Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-779@events.ncbj.gov.pl DESCRIPTION:Speakers: Paweł Krawczyk (NCBJ)\nThe idea of building a 4th g eneration accelerator based light source at NCBJ has been developed for al most 20 years. The concept came to reality in 2018 after receiving the fun ding for the construction of the Polish Free Electron Laser – PolFEL (or formally\, its first stage ). The PolFEL device will be driven with an RF continuous-wave superconducting linac\, including a superconducting injec tor furnished with an in house developed lead film superconducting photoca thode. The linac will be split into three branches feeding the undulator chains dedicated to THz\, IR and UV/VUV coherent electromagnetic radiation emission\, respectively. In effect\, PolFEL will provide a wide range of light with wavelengths from 0.6 mm down to 60 nm. In addition\, the facili ty will be furnished with a station generating short X-ray pulses in the i nverse Compton scattering process. In the presentation\, we will describe the PolFEL facility and its research capabilities in more details. The cu rrent status of the project and its timetable will be also presented. Fina lly\, we will indicate the plans for further extension of the facility in the second stage the preparation for which should start right after the co mpletion of the current stage.\n\nhttps://events.ncbj.gov.pl/event/75/cont ributions/779/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/779/ END:VEVENT BEGIN:VEVENT SUMMARY:Magnetospectroscopy of a CdTe/ Cd$_{0.8}$Mg$_{0.2}$Te quantum wel l DTSTART;VALUE=DATE-TIME:20220706T153500Z DTEND;VALUE=DATE-TIME:20220706T155000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-758@events.ncbj.gov.pl DESCRIPTION:Speakers: Jerzy Łusakowski (University of Warsaw)\nWe present results of magnetotransport and magnetospectroscopic studies on a single CdTe quantum well (QW) with Cd$_{0.8}$Mg$_{0.2}$Te barriers modulation-d oped with Iodine donors. Experiments were carried out at temperatures of a bout 1.8 K as a function of magnetic field up to 10 T and included measure ments of: transport\, THz transmission\, photoluminescence\, optically de tected cyclotron resonance (ODCR) and reflectivity in the visible range. \ n\nTransport measurements determined concentration of a two-dimensional el ectron gas (2DEG) in the CdTe QW to be $3.3\\times 10^{11}$ cm$^{-2}$ in t he darkness $3.4\\times 10^{11}$ cm$^{-2}$ after over the barrier illumina tion. These values were used to establish the filling factors in the anal ysis of optical spectra.\nTHz transmission measurements allowed us to dete rmine the effective mass of electrons which was to be $(0.1020\\pm0.0006) m_e$\, consistent with earlier studies on CdTe QWs. Magnetoluminescence spectra showed the Fermi-edge-singularity shape that is characteristic fo r the case of QWs with such a high 2DEG concentration and allowed us to ob serve a band-to-band recombination between Landau levels in the conduction and valence bands. Combined with the determined mass of the free electron \, this allowed us to determine the mass of the hole involved in the lumi nescence process. ODCR spectra showed that heating of 2DEG by absorption o f a THz radiation leads to redistribution of electrons between all observa ble Landau levels\, not just those adjacent to the Fermi energy. Reflecti vity measurements revealed the presence of multiple resonances and provide d valuable information about the energetical structure of levels of the QW under the influence of the internal electric field. \n\nIn conclcusio n\, we have shown on the example of CdTe/Cd$_{0.8}$Mg$_{0.2}$Te QW that th e combination of magnetotransport with THz and VIS magnetospectroscopy a llows for a thorough characterization of the structure of quantum levels in a two-dimensional system. The comprehensive procedure applied in our s tudy show the way to plan and carry out experiments on less known semicond uctor objects. \n\n\n \n \nThis research was partially supported by the Po lish National Science Centre grant UMO-2019/33/B/ST7/02858.\n\nhttps://ev ents.ncbj.gov.pl/event/75/contributions/758/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/758/ END:VEVENT BEGIN:VEVENT SUMMARY:3D printable materials for use in dual band optical structures DTSTART;VALUE=DATE-TIME:20220706T153500Z DTEND;VALUE=DATE-TIME:20220706T155000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-718@events.ncbj.gov.pl DESCRIPTION:Speakers: Michal Walczakowski (Military University of Technolo gy)\nPursuit after new technical and scientific achievement is a driving f orce for new solutions in research equipment. Furthermore\, highest ever c ompetition is pushing time of rapid development to the limits. Evolution o f science lead us to a place where two or more IR radiation wavelengths a re necessary to conduct some experiments. In some cases wavelength separat ion is significant\, mixing one from THz range and other from NIR of MIR. Working with whole IR spectrum is possible with usage of reflective optics . Inconvenience occurs when one have to work with THz range\, where optica l elements are significantly bigger. The 4” mirrors are standard and eve n 8”\, or bigger elements aren’t uncommon. This fact may impact experi mental setup layout and in cases of facilities like free electron laser\, where two wavelength operation is associated with doubling beam guiding in stallation\, simplifying even a part of it may be desirable. Guiding both THz and MIR can be done when using only reflective optics\, but there is v ery limited Materials that can be usable for manufacturing a passive optic al elements that work in both bands could lead to reduction of the number of elements. That can translate to experiment optimization\, reduce cost o f elements and shorter time of preparing experimental setup. \n\nIn these study selection of materials suitable for manufacturing of optical 3D stru ctures was presented. A number of samples with different thickness was pre pared and measured. The issue of the characterization of various materials in wide\, optical spectral range is a common day task\, unless material i tself behaves differently in situations when it is homogeneous and when it is formed in the 3D printing process.\n\nFirst\, samples were measured in THz range with the Time domain spectroscopy (TDS) in 0.3-2.5 THz (1 mm – 150 um) frequency band. Transmission of the materials was measured and attenuation coefficients were determined. Spectral characterization of t he samples in the range from 2 THz up to 1.5 um was conducted with FTIR sp ectroscopy. Based on this set of results influence of 3D print on the spec trum was shown. Discussion of the results includes influence of different polarization used in measurements\, effects occurring with samples of diff erent thickness and 3D printing side effects. \n\nThe objective is to ena ble designing of the optical elements using spectral properties of materia l combined with curvatures of the element. Design of optics that can work differently on two spectral bands takes advantage of implementing addition al features like wavelength selectivity in THz band or different focal poi nts.\n\nhttps://events.ncbj.gov.pl/event/75/contributions/718/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/718/ END:VEVENT BEGIN:VEVENT SUMMARY:Mobility Spectrum Analysis for Electric Charge Carriers in HgCdTe/ HgTe/HgCdTe Quantum Well with Inverted Bands Order Close to Topological Tr ansition DTSTART;VALUE=DATE-TIME:20220706T153500Z DTEND;VALUE=DATE-TIME:20220706T155000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-753@events.ncbj.gov.pl DESCRIPTION:Speakers: Jacek Przybytek (CENTERA Laboratories\, Institute of High Pressure Physics\, Polish Academy of Sciences\, Poland & University of Warsaw\, Poland)\nBased on the experimental small-field magnetotranspor t measurements performed for 7.1 nm-width HgCdTe/HgTe/HgCdTe quantum well with inverted band structure order\, we will present results of the mobil ity spectra analysis in dependence on both the gate voltage (charge carrie r concentration) and temperature.\nWe will discuss these data from the poi nt of view of the band structure picture and possible scattering mechnisms of various types of carries in the system.\n\nhttps://events.ncbj.gov.pl/ event/75/contributions/753/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/753/ END:VEVENT BEGIN:VEVENT SUMMARY:Selected issues of influence irradiation on characteristics of sup erconducting elements in modern FEL-s facilities DTSTART;VALUE=DATE-TIME:20220706T145000Z DTEND;VALUE=DATE-TIME:20220706T150500Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-708@events.ncbj.gov.pl DESCRIPTION:Speakers: Jacek Sosnowski (NCBJ)\nCurrently developed free ele ctron lasers facilities more and more frequently use superconducting eleme nts in theirs advanced constructions. Most frequent examples of these appl ications are the superconducting electromagnets\, current leads to them an d especially superconducting cavities. The same concerns the superconducti ng shields\, as well as superconducting correction coils conducting the el ectron beam along the appropriate way. Beside of numerous advantages of us ing these new materials\, there arise however then new effects\, especiall y connected with the influence of the irradiation appearing in FEL acceler ators on the current carrying properties of the unique superconducting mat erials. The irradiation is caused here by primary electrons beam as well a s by secondary beams\,composed from neutrons\, gamma-rays and photons\, wh ich are created then. In the paper are discussed therefore the advantages but also problems arising\, while using superconductors in modern accelera tors\, working in irradiation environment. It is shown in which way the ir radiation effects damage the subtle structure of superconducting materials \, including 2D HTc superconductors\, in which columnar defects are formed . In the paper it will be analysed\, in which way these structural defects influence the current carrying properties of the superconducting material s. It will be developed therefore the energetical approach to the process of capturing on the nano-defects of the magnetic pancake vortices\, charac teristic for HTc superconductors. Various initial positions of the capture d vortices will be analysed\, movement of them will lead to the potential barrier decrease. The influence of the radiational defects on the current -voltage characteristics will be investigated then and maximal current den sity values detected\, as the function of irradiation intensity and physi cal parameters as magnetic field and temperature. These researches have th erefore pure scientific meaning as well as can be useful for prediction of the proper work of superconducting solenoids and current leads to them in radiational environmen. Analysis can be also extended on the case of micr o-cracks and dislocational defects formed during the mechanical winding of superconducting coils and arising then bending strain.\n\nhttps://events. ncbj.gov.pl/event/75/contributions/708/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/708/ END:VEVENT BEGIN:VEVENT SUMMARY:Shielding with Graphene Epoxy Composites in the Extended THF Band from 0.25 to 4.00 THz DTSTART;VALUE=DATE-TIME:20220706T140500Z DTEND;VALUE=DATE-TIME:20220706T142000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-745@events.ncbj.gov.pl DESCRIPTION:Speakers: Kamil Stelmaszczyk (CENTERA Laboratories\, Institute of High Pressure Physics PAS\, Warsaw\, Poland)\nWe report on THz charact erization of graphene composites in the extended THF band from 0.25 to 4.0 0 THz. The composites\, containing low percent by weight fractions (wt.%) of graphene form 0.8wt.% to 1.2wt.%\, were investigated using THz- Time Do main Spectroscopy (THz-TDS). Based on the measured transmission and reflec tion coefficients\, the shielding effectiveness parameters of reflection ( SER) and transmission (SET) were calculated to determine the shielding eff ectiveness of absorption (SEA). The procedure comprised each of the weight fractions of graphene.\nWhile the SER was found to be less than ~0.6 dB w ithin the measured frequency range and for all the samples\, the SET and S EA were found to be substantially higher\, firmly above ~70 dB with graphe ne loading of 1.2wt.% at the frequency f=1.6 THz. Such unexpectedly high t otal shielding effectiveness resulted mostly from absorption\, due to the measured low absolute values of SER.\nThe fact that a simple EM energy red irection via conduction-based reflection was not primary energy loss mecha nism is favorable from the point of view of EMI shielding because contrary to metal-based conducting coatings or metallic nanocomposites\, the graph ene-based epoxy materials do not spread unwanted EM radiation from one pla ce to another. Additionally\, they have low weights.\nBy performing the Be er-Lambert calculations\, we show that even a thin-film or a spray coating with a thickness in the few-hundred-micrometer range of lightweight\, not conducting and not reflecting graphene epoxy composites can be sufficient for blocking THz radiation in many practical applications\, where the shi elding of EM by ~20–30 dB is typically sufficient. Thus\, the fabricated composites can be successfully used as effective ultra-thin stealth mater ials.\n\n[1]. Z. Barani\, K. Stelmaszczyk\, et al.\, Appl. Phys. Lett. 120 \, 063104 (2022)\n\nhttps://events.ncbj.gov.pl/event/75/contributions/745/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/745/ END:VEVENT BEGIN:VEVENT SUMMARY:Terahertz Time-Domain Spectroscopy for artworks analysis DTSTART;VALUE=DATE-TIME:20220706T135000Z DTEND;VALUE=DATE-TIME:20220706T140500Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-747@events.ncbj.gov.pl DESCRIPTION:Speakers: Ewelina Karpierz-Marczewska (CENTERA Laboratories\, Institute of High Pressure Physics PAS)\, Kamil Stelmaszczyk (CENTERA Labo ratories\, Institute of High Pressure Physics PAS)\nIn recent years\, tera hertz (THz) techniques have been used in many fields of applications\, mos t of all in space\, telecommunication and security industry. However\, the number of projects connecting THz technologies with Science and Culture i s constantly increasing and the conservation and restoration of art\, e.g. paintings or sculptures\, belongs to the most evolving areas in this doma in. \nThe conventional spectroscopic and imaging techniques for the analys is of art pieces comprise: X-ray\, Ultraviolet (UV)\, Infrared (IR) and la ser spectroscopy\, but even if well established\, they may have negative i mpact on the objects under analysis due to high energies of photons. Only IR reflectography is considered as safe method\, but in many cases it is s imply not sufficient. THz imaging is a non-invasive and safe technique whi ch extends spectral bands of X-ray and IR spectroscopies to lower and less invasive photon energies. Several years ago\, it was proposed for the stu dy of artworks and research in the Uffizi Gallery in Florence and recent d evelopments in THz technology\, in particular time domain techniques\, ena ble easier and more effective usage of THz radiation in the field of art c onservation.\nThe best established and most promising THz time domain tech nique is known as Terahertz Time Domain Spectroscopy (THz-TDS). It can be used to characterize and identify various materials in the THz wavelength range\, basing on the intensity of the wave passing through the sample or the wave reflected from it. In addition\, the measurement of the phase of the THz wave makes it possible to study the parameters characterizing macr oscopic electromagnetic properties of materials\, as extension to typical molecular absorption spectra.\nInspired by successful applications of THz techniques in the Uffizi Gallery in Florence\, the Louvre in Paris or muse ums in Milan\, we decided at CENTERA to prepare THz-TDS experiments\, whic h provide new information about the internal physical structure of painti ngs or frescos such as canvases\, paper and even dry plaster. THz waves ha ve good penetration depths in all these materials (~1 cm) and with broad s pectral bandwidth of ps THz pulses (0.1 - 10 THz)\, it is be possible to i dentify the substances that the paint consists of basing on the registrati on of THz absorption spectra. As a result\, one can learn about such prope rties of the analysed pieces of arts such as the depths of subsequent pain t layers or pigments. \nDuring investigations a specially prepared picture has been used. It was prepared using two types of paints: oil and acrylic \, covering its selected areas with different amount of varnish (different layer thickness). Then the whole painting was painted over with white pai nt. Two dimensional (x-y) scans of the entire painting were made with THz- TDS spectrometer in both transmission and reflection modes with the resolu tion better than 1 mm. The obtained results will be presented on the poste r.\n\nhttps://events.ncbj.gov.pl/event/75/contributions/747/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/747/ END:VEVENT BEGIN:VEVENT SUMMARY:Multichannel transmission for the future wireless THz telecommunic ation links DTSTART;VALUE=DATE-TIME:20220708T095000Z DTEND;VALUE=DATE-TIME:20220708T101000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-717@events.ncbj.gov.pl DESCRIPTION:Speakers: Paweł Komorowski (Institute of Optoelectronics\, Mi litary University of Technology)\nTerahertz (THz) radiation brings the att ention of researchers and entrepreneurs for at least a few decades and has already found numerous applications in various areas\, such as medical di agnostics\, nondestructive testing\, detection of dangerous materials and objects\, security or telecommunication. This work focuses on the latter a rea of potential applications and aims at the development of the multiplex ing methods for the future THz data transmission links. We propose the uti lization of the properly designed THz diffractive optical elements (THz-DO Es) for manipulation of the THz waves on both sides of the data transmissi on link to\, respectively\, multiplex and demultiplex signals.\nDOEs intro duce defined attenuation and phase retardation distributions to the illumi nating optical field. Clever adjustment of these parameters allows to resh ape incoming radiation into almost arbitrarily chosen patterns. Moreover\, the size of the crucial elements of such structures depends linearly on t he wavelength\, which in case of THz and sub-THz bands is in order of sing le millimeters or its fractions. Therefore\, in many cases\, THz-DOEs can be manufactured using relatively simple and cheap techniques\, such as ext rusion-based 3D printing.\n In this work\, we present methods of separatio n of THz beams propagating in the single optical channel\, also with the f requency division. We have designed\, optimized and manufactured THz-DOEs redirecting the incoming radiation into several focal spots. Two approache s have been investigated – single-frequency and multi-frequency operatio n. In the first case\, a monochromatic THz beam is divided into three sepa rate focal spots\, while in the second one a polychromatic beam is redirec ted at an angle dependent on the frequency. All structures have been succe ssfully verified experimentally and the obtained results comply with the t heoretical simulations. Moreover\, a setup demonstrating simultaneous dual -channel transmission at 300 GHz and 330 GHz has been demonstrated.\n\nhtt ps://events.ncbj.gov.pl/event/75/contributions/717/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/717/ END:VEVENT BEGIN:VEVENT SUMMARY:Detecting trace amount of contamination or additives in commercial -grade gasolines by means of THz-TDS time-of-flight spectroscopy DTSTART;VALUE=DATE-TIME:20220708T080000Z DTEND;VALUE=DATE-TIME:20220708T082000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-744@events.ncbj.gov.pl DESCRIPTION:Speakers: K. Stelmaszczyk (CENTERA Laboratories\, Institute of High Pressure Physics PAS\, Sokołowska 29/37\, 01-142 Warsaw\, Poland)\n Terahertz Time-Domain Spectroscopy (THz-TDS) has recently become an attrac tive analytical technique in gas\, liquid or solid state phase which uses ultra-short bursts of terahertz radiation for probing of the medium proper ties. We show that straight forward and fast determination of propagation times of THz pulses transmitted through gasoline samples is adequate to de tect small\, a few hundred ppm fractions (percent by weight %wt.) of water and other contamination in commercial-grade gasoline.\nA series of measur ements conducted to examine time-profiles of picosecond THz pulses\, i.e. their peak amplitude time-positions and delays\, was used to investigate c ompositional change in gasoline. More precisely\, the Time-of-Flights (TOF s) of the pulses passing through pure gasoline samples were compared with those transmitted through gasoline mixtures containing de-ionized water an d isopropanol at calibrated weight fractions. It was found that the differ ence between the TOFs expressed as a function of admixture concentration h as a universal linear character\, independently of admixture type.\nIn_ord er to explain this linear dependence\, the obtained results were compared with the Gladstone-Dale mixing rule\, which presumes that refractive index of a pseudo binary mixture can be expressed as a weighted sum of refracti ve indices of solvent and dissolved substance with the weights given by ma ss fractions of the two constituents. We show that when applying this simp le model an excellent agreement between measurements and theoretical calcu lations is obtained\, proving good solubility of dissolved substance in ga soline\, when the assumption on pseudo binary mixture of gasoline is fulfi lled [1].\n\n[1]. K. Stelmaszczyk\, E. Karpierz-Marczewska\, et al.\, Appl . Sci. 12\, 1629\, 2022\n\nhttps://events.ncbj.gov.pl/event/75/contributio ns/744/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/744/ END:VEVENT BEGIN:VEVENT SUMMARY:Measurements of Electromagnetic Properties of Low-loss Dielectrics in the mm-Wave and sub-THz Bands DTSTART;VALUE=DATE-TIME:20220708T072000Z DTEND;VALUE=DATE-TIME:20220708T074000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-738@events.ncbj.gov.pl DESCRIPTION:Speakers: Pawel Kopyt (Warsaw Univ. of Technology)\nLow-loss m aterials find multiple applications in the modern electronics industry wit h dielectric-based substrates used in printed circuit boards (PCB’s) bei ng a prominent example. Others include ceramic materials and plastics empl oyed in packages for integrated circuits or supportive and protection stru ctures for integrated antennas. There is a strong interest in efficient an d easy-to-use methods to characterize all such materials at higher frequen cies for dielectric constant (Dk) and dielectric loss (Df). \n\nThe main g oal of this paper is to present a novel approach to material measurements at the mm-wave band based on high-Q Fabry-Perot resonators\, which has bee n found efficient up to the frequency of 120 GHz. The upper limit is a res ult of available coaxial transmission lines employed to excite the resonat or loaded with a sample under test and is expected to rise when new types of the lines (of smaller diameters) are offered.\n\nIn order to overcome t his limitation we have attempted to combine the dedicated Fabry-Perot reso nator with sub-THz spectrometers operating in either time- or frequency-do main. As a result\, low-loss materials can be efficiently characterized in a ultra-broad frequency band extending from ca. 10 GHz up to hundreds of GHz employing\, first\, the mm-wave set-up based on a resonator and a vect or network analyser (VNA) and\, then\, a sub-THz set-up with a spectromete r as a source of test signals. The effort will be divided into two tasks a imed at obtaining a set of numerical and mechanical models of structures w ith couplings\, which provide as weak loss of cavity’s Q-factor as possi ble.\n\nThe results in form of Dk and Df data on some dielectric materials measured up to the sub-THz bands will be presented.\n\nhttps://events.ncb j.gov.pl/event/75/contributions/738/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/738/ END:VEVENT BEGIN:VEVENT SUMMARY:Observation of Terahertz-Induced Magnetooscillations in Graphene DTSTART;VALUE=DATE-TIME:20220707T152500Z DTEND;VALUE=DATE-TIME:20220707T154500Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-715@events.ncbj.gov.pl DESCRIPTION:Speakers: Erwin Mönch (Terahertz Center (TerZ)\, University o f Regensburg\, Germany)\nAlmost twenty years ago\, experiments on high-mob ility GaAs/AlGaAs heterostructures revealed strong magnetoresistance oscil lations excited by microwave illumination [2\,3]. These oscillations are $ 2\\pi$-periodic in $B_\\mathrm{CR}/B\\equiv\\omega/\\omega_c$\, and thus r eflect commensurability between the photon energy $\\hbar\\omega$ and sepa ration $\\hbar\\omega_c$ between neighboring Landau levels [4]. Despite su perior quality of modern graphene devices\, no counterpart of such effects (apart from physically related phonon-assisted resistance oscillations [5 ]) has been reported so far in this class of materials.\n\nWe demonstrate the emergence of a terahertz analogue of microwave induced resistance osci llations (MIRO) [2\,3]\nin high-mobility multi-terminal graphene devices\, termed below as THz-induced magnetooscillations (TIMO) [1]. The linear sp ectrum of graphene results in non-equidistant spectrum of Landau levels (L Ls). The spacing between LLs at the Fermi energy depends on the carrier de nsity $n$ as $\\hbar\\omega_c = e B v_\\mathrm{F}/\\sqrt{\\pi n}$. We ind eed observe that the fundamental frequency of TIMO $B_\\mathrm{CR}=B \\ome ga/\\omega_c\\propto \\sqrt{n}$ is controlled by $n$ and thus can be tuned by applying the gate voltage. We also find that\, in line with previous o bservations in other materials [4]\, the nodes of TIMO in graphene occur a t integer $B_\\mathrm{CR}/B = 1\, 2\, \\ldots$.\n\nIn sharp contrast to co nventional MIRO in other materials\, where oscillations become strongly su ppressed already at liquid helium temperature\, we demonstrate that TIMO i n graphene persist above the liquid nitrogen temperature. Preliminary meas urements at higher THz frequencies indicate that the amplitude of TIMO at $f = 1.63$ and $2.54$ THz relative to $f = 0.69$ THz is larger than expect ed from predicted $f^{-4}$ scaling [4]. The above peculiarities of TIMO in graphene require further focused studies. An almost linear power dependen ce of the amplitude of oscillations\, with a weak tendency to saturation a t highest input power of $20$ mW\, indicates that much stronger TIMO can b e induced by more powerful THz sources.\n\nThe presented observations exte nd the family of radiation-induced nonequilibrium effects in graphene and offer opportunities for deeper understanding of the MIRO phenomenon as wel l as scattering and relaxation mechanisms in this material.\n\n\n[1] E. M önch \\textit{et al.}\, Nano Lett. \\textbf{8}\, 5943 (2020).\n[2] M. A. Zudov \\textit{et al.}\, Phys. Rev. B \\textbf{64}\, 201311(R) (2001).\n[3 ] P. D. Ye \\textit{et al.}\, Appl. Phys. Lett. \\textbf{79}\, 2193 (2001) .\n[4] I. A. Dmitriev \\textit{et al.}\, Rev. Mod. Phys. \\textbf{84}\, 17 09 (2012).\n[5] P. Kumaravadivel \\textit{et al.}\, Nat. Comm. \\textbf{10 }\, 3334 (2019).\n\nhttps://events.ncbj.gov.pl/event/75/contributions/715/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/715/ END:VEVENT BEGIN:VEVENT SUMMARY:Graphene plasmonics: THz nonlinearities beyond thermal effects DTSTART;VALUE=DATE-TIME:20220707T090000Z DTEND;VALUE=DATE-TIME:20220707T094500Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-754@events.ncbj.gov.pl DESCRIPTION:Speakers: Martin Mittendorff (University of Duisburg-Essen)\nG raphene is a very versatile material for optoelectronics or nonlinear opti cs in a large spectral range\, in particular for THz radiation. One drawba ck is the low interaction volume between THz radiation and the single atom ic layer\, which limits the light matter interaction at elevated photon fr equencies. During the recent years it has been shown that patterning graph ene into plasmonic structures\, e.g. ribbons or disks\, can shift the rath er strong optical response of free charge carriers at low frequencies to a more confined plasmonic resonance at higher frequencies. The size of the structure\, in combination with the carrier density\, determines the plasm on frequency\, that can be tailored in a wide range. Beyond the linear abs orption\, the nonlinear optical properties are enhanced by about two order s of magnitude under resonance compared to unpatterned graphene. Here we p resent a set of studies that quantify the thermal effect when the structur es are excited with strong laser pulses: the charge carriers are heated ef ficiently\, as their specific heat is rather low\, which leads to a decrea sed chemical potential and therewith a reduced plasmon frequency. Compared to thermal nonlinearities in conventional materials\, thermal nonlinearit ies in graphene are very fast as the hot charge carriers cool down within several tens of picoseconds. Polarization-resolved pump-probe measurements on graphene disks revealed nonlinear absorption beyond thermal effects\, i.e. plasmonic nonlinearities: thermal and nonthermal effect can be distin guished by using cross- and co-polarized pump-probe measurements. Numerica l simulations considering thermal as well as plasmonic nonlinearities\, ma tch the observed signals well\, giving a complete picture of the nonlinear processes in graphene plasmons.\n\nhttps://events.ncbj.gov.pl/event/75/co ntributions/754/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/754/ END:VEVENT BEGIN:VEVENT SUMMARY:Understanding the microscopic origin of Terahertz conductance in s trained polycrystalline graphene DTSTART;VALUE=DATE-TIME:20220707T074500Z DTEND;VALUE=DATE-TIME:20220707T083000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-739@events.ncbj.gov.pl DESCRIPTION:Speakers: Simone Zanotto (NEST\, Istituto Nanoscienze – CNR) \nThe conductivity of polycrystalline graphene in the THz range is relevan t for many applications. However\, a full understanding of the underlying physics has not yet been achieved\, due to the lack of reliable models of carrier transport in polycrystalline nanomaterials. In this work\, we rela te the structural deformation in strained graphene with the deviation from the Drude conductance. To this end\, THz time-domain spectroscopy has bee n performed as function of the graphene deformation to extract the frequen cy dependence of the permittivity. Experimental findings are interpreted\, for the first time\, by means of a fully atomistic model that provides a novel microscopic interpretation of the observed Drude-Smith behavior.\nEx perimentally we have studied a thin polymer membrane\, on top of which a g raphene monolayer has been transferred. The sample is mounted on a mandrel with four clamps\; by operating on the mandrel tightening mechanism\, the sample can be strained. The sample is then analyzed with two spectrometer s: a THz-TDS instrument\, operating in the 0.3-2 THz spectral range\, a FT IR instrument\, operating either in the FIR (2-10 THz) or in the MIR (10-1 00 THz) spectral ranges depending on the employed beam-splitter and detect or. The strain strongly affects the 0.3-2 THz region\, while the 10-100 TH z region is almost unaffected. \nTo interpret the observed spectra\, we ca lculated by means of the multilayer scattering matrix method the trasmitta nce. The SM method employed here is the last “PPML” package available online from some of the authors[1]\; its main input are the thicknesses of the layers and the conductivity of graphene. After an unsuccessful attemp t to describe the graphene conductivity through a Drude model\, we applied the Drude-Smith model\, in its recent revision by Cocker et al.[2] This m odel quantifies the conductivity of a multi-domain conductor\, a situation that may well describe our large-size poly-crystalline graphene sample. W ith this model we obtained a good agreement with experiments. We supported such explanation by a comparison with atomistic simulations relying on th e wFQ approach[3]\, allowing a direct comparison with experimental results . In this scenario\, the atomistic nature of wFQ is suitable for the descr iption of cracks\, bond elongations and the mutual motion of grain boundar ies. Thus\, wFQ can indeed model complex carriers transport in strained gr aphene. The physical parameters returned by wFQ are exploited to better in terpret the meaning of Drude-Smith parameters\, for which a microscopic in terpretation is then given.\n\n[1] https://it.mathworks.com/matlabcentral/ fileexchange/55401-ppml-periodically-patterned-multi-layer\n[2] Cocker\, T . L. et al.\, Phys. Rev. B 96\, 205439 (2017)\n[3] Giovannini\, T. et al.\ , J. Phys. Chem. Lett. 11\, 7595 (2020)\n\nhttps://events.ncbj.gov.pl/even t/75/contributions/739/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/739/ END:VEVENT BEGIN:VEVENT SUMMARY:Towards THz communications: channel characteristics and uncertaint ies DTSTART;VALUE=DATE-TIME:20220706T124000Z DTEND;VALUE=DATE-TIME:20220706T130000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-722@events.ncbj.gov.pl DESCRIPTION:Speakers: Milda Tamošiūnaitė (Department of Optoelectronics \, Center for Physical Sciences and Technology\, Sauletėkio al. 3\, Vilni us\, Lithuania)\nFuture wireless technologies will require very high data rates and low latency to satisfy the nearly exponential growth of worldwid e data traffic [1]. Terahertz (THz) technologies with its broad unallocate d frequency band (0.1‑10 THz) can be a promising potential solution. Alo ng with extreme densification of the infrastructure and highly directional beams\, it is the key enabling technology of the 6th generation (6G) wire less networks. However\, due to path loss\, THz communications is envision ed for only short-range wireless applications.\nTHz atmospheric absorption spectra are well documented and eight spectral windows with a relatively low atmospheric absorption are identified [2]\, but challenges due to free space losses\, fog and rain have to be considered when evaluating the fea sibility of THz communications at particular conditions. For example\, usu ally events of heavy rain are taken into account as attenuation of approxi mately 10 dB/km [2]\, but due to the nature of heavy rain (high intensity\ , short duration)\, the actual values might significantly mismatch. This a pproach was satisfactory during the early development of the THz wireless communications technology and so-called THz technology gap (while lack of compact energy-efficient high-power THz transmitters and low-noise high-se nsitivity receivers has limited the practical use of the THz band for comm unication systems [3]). Recent achievements in semiconductor technologies are closing the technology gap\, practical applications are approaching an d channel characteristics need to be assessed more carefully in order to a ccurately characterize possible scenarios. \nThe state-of-art of channel c haracteristics modelling is presented\, as well the efforts to carry out s tatistical calculations. Statistical peculiarities of THz wave attenuation in heavy rain conditions in the case of short-range communications with n arrow beam high-gain antennas were evaluated. Calculations were performed emulating both drop size distributions of the real rain and the laboratory -controlled rain described in literature. The results predicted a new futu re application possibility for such laboratory-based experiments (e.g. pre dict the performance of wireless THz data transmission links when the resi lience margin is required). Such experiments can be employed to primarily predict the performance of data transmission links. \n\n[1] https://www.er icsson.com/en/reports-and-papers/mobility-report/dataforecasts/mobile-traf fic-forecast \n[2] Nagatsuma\, T. (2016)\; https://doi.org/10.1038/nphoton .2016.65 \n[3] Akyildiz\, I.F. (2022)\; https://doi.org/10.48550/arXiv.211 2.13187\n\nhttps://events.ncbj.gov.pl/event/75/contributions/722/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/722/ END:VEVENT BEGIN:VEVENT SUMMARY:Quantum GaAs/AlGaAs superlattice: multiphoton and high-frequency gain effects at room temperature DTSTART;VALUE=DATE-TIME:20220706T115500Z DTEND;VALUE=DATE-TIME:20220706T124000Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-721@events.ncbj.gov.pl DESCRIPTION:Speakers: Gintaras Valušis (Department of Optoelectronics\, C enter for Physical Sciences and Technology\, Sauletėkio al. 3\, Vilnius\, Lithuania)\nSemiconductor superlattices -- artificial periodic structures consisting of ultrathin layers where by variation of their width\, doping level and profile one can tailor their optical and electronic properties in a desirable way – can be found as an attractive environment to invest igate various high-frequency phenomena [1\,2]. \nIn the given communicatio n\, we present the first experimental observation of the cavityless dissip ative parametric generation in subcritically doped GaAs/AlGaAs quantum sup erlattice. The effect\, theoretically predicted more than a decade ago [3 \, 4] and being inherent to optical systems [5]\, was discovered in molecu lar beam epitaxy grown silicon doped GaAs/AlGaAs quantum superlattice. To enable uniform electric field in the structure the superlattice was sandwi ched between non-ohmic contacts – Schottky contact on the top and hetero structure underneath. The structure was then processed into mezas and plac ed into a waveguide for microwave excitation of 8.45 GHz pump microwave ra diation for DC biased experiment at room temperature.\nA spectral response associated with both the nondegenerate and degenerate parametric processe s and harmonics of the pump frequency was clearly demonstrated\; generatio n at fractional frequencies due to several multiphoton processes occurring simultaneously was revealed. It is shown that the incident transverse ele ctromagnetic microwave is transformed into a longitudinal electrostatic wa ve which propagates with electron drift velocity experiencing negative abs orption due to the Esaki-Tsu nonlinearity. The established slow propagatin g drift-relaxation mode (with velocity of about 1000 times lower than the speed of light in the material) enables to reach tremendous high-frequency gain levels of 104 cm-1\, which can be extended up to THz frequencies [6] . \n\n[1] C. Waschke et al.\, PRL 70\, 3319 (1993).\n[2] A. Ignatov et al. \, PRL 70\, 1996 (1993).\n[3] T. Hyart et al.\, APL 89\, 132105 (2006).\n[ 4] T. Hyart et al.\, PRL 98\, 220404 (2007).\n[5] R. Byer\, Journal of Non linear Optical Physics and Materials 6\, 549-592 (1997).\n[6] V. Čižas e t al.\, Phys. Rev. Lett.\, in press (2022).\n\nhttps://events.ncbj.gov.pl/ event/75/contributions/721/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/721/ END:VEVENT BEGIN:VEVENT SUMMARY:Pressure tuning of THz cyclotron resonance in HgCdTe alloys DTSTART;VALUE=DATE-TIME:20220706T094500Z DTEND;VALUE=DATE-TIME:20220706T100500Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-752@events.ncbj.gov.pl DESCRIPTION:Speakers: Maria Szoła (Institute of High Pressure Physics PAS \; Laboratoire Charles Coulomb\, UMR\, CNRS)\nThe main inspiration of the current work was the results previously obtained by the part of the co-aut hors in MCT samples by temperature-dependent THz magnetospectroscopy [1]. The latter revealed the evolution of the energy band-gap with temperature vanishing at a certain temperature. It was shown that although the fermion s in MCT alloys are represented by the admixture between the Dirac and spi n-1 particles [2]\, they indeed support the pseudo-relativistic descriptio n involving the particle rest-mass and Fermi velocity. This work focuses o n the band-gap evolution of Hg1-xCdxTe epitaxial alloys with cadmium conte nt (*x*) and the hydrostatic pressure (*p*) probed by THz magnetospectrosc opy. We study three MCT samples with different cadmium content *x* = 0.15\ , 0.16 and 0.17. THz magnetospectroscopy of the sample with *x* = 0.15 was performed in the pressure cell in the range of p from 0 to 3.83 kbar.\nTh e THz magnetospectroscopy was performed at 2 K using thinned Allan-Bradley carbon resistor as a bolometer. As a source of THz radiation\, the far-in frared molecular laser and Virginia diodes (VDI) source operating at 0.63 THz\, 1.61 THz\, 1.84 THz\, 2.52 THz\, 3.11 THz\, and 4.25 THz were used. To create hydrostatic pressure in the pressure cell a mixture of transform er oil and kerosene was used. The fitting analysis agrees with experimenta l results and pseudo-relativistic description with Fermi velocity *c* = 1. 0·106 m/s independent of hydrostatic pressure p and Cd content *x*. \nWe have investigated THz magnetospectroscopy of pseudo-relativistic fermions in Hg1-xCdxTe alloys with different cadmium content. The measured transmis sion spectra have featured resonant absorption lines corresponding to the optical transition between Landau levels of pseudo-relativistic fermions. Analysis of experimental data within the pseudo-relativistic description [ 1] allowed us to determine the rest mass m and Fermi velocity *c* of pseud o-relativistic fermions. The band-gaps *Eg* = 2mc^2 are in good agreement with the previously measured dependence on Cd content. The values of c are shown to be independent of Cd content and hydrostatic pressure.\n\nThis r esearch was partially supported by the Foundation for Polish Science throu gh a TEAM/2016-3/25 and by CENTERA Laboratories in the frame the Internati onal Research Agendas program for the Foundation for Polish Sciences co-fi nanced by the European Union under the European Regional Development Fund (No. MAB/2018/9). It was also supported by the Terahertz Occitanie Platfor m\, by CNRS through IRP.\n\nReference: \n[1] F. Teppe et al. “Temperatur e-driven massless Kane fermions in HgCdTe crystals” Nature Comm. 7\, 125 76 (2016).\n[2] S.S. Krishtopenko et al. “Hybridization of topological s urface states with a flat band” J. Phys.: Condens. Matter 32\, 165501 (2 020).\n\nhttps://events.ncbj.gov.pl/event/75/contributions/752/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/752/ END:VEVENT BEGIN:VEVENT SUMMARY:Auger scattering in massless Dirac and Kane materials DTSTART;VALUE=DATE-TIME:20220706T090000Z DTEND;VALUE=DATE-TIME:20220706T094500Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-742@events.ncbj.gov.pl DESCRIPTION:Speakers: Stephan Winnerl (Helmholtz-Zentrum Dresden-Rossendor f)\nWe present an overview that sheds light into the carrier dynamics of i n Landau-quantized Dirac and Kane systems\, namely graphene and mercury ca dmium telluride (MCT). The non-equidistant Landau-ladder makes these mater ials highly attractive for realizing the old dream of the semiconductor ph ysics community to fabricate a Landau-level laser. For a recent review on this topic\, see Ref. [1]. In such a laser\, stimulated emission is achiev ed between a pair of Landau levels and the emission wavelength can be tune d by the strength of the magnetic field. In graphene\, we found evidence f or strong Auger scattering for the lowest allowed transitions LL$_{-1}$ → LL$_{0}$ and LL$_{0}$ → LL$_{1}$ [2]. These energetically degenerate transitions can be distinguished by applying circularly polarized radiati on of opposite polarization. In this configuration\, Auger scattering can cause depletion of the LL0 level even though it is optically pumped at the same time. Recently\, we have investigated the LL$_{-2}$ → LL$_{1}$ and LL$_{-1}$ → LL$_{2}$ transition under strong optical pumping. This tran sition is a candidate for the lasing transition for a Landau-level laser. We observed non-equilibrium carrier distributions by selective pumping bef ore thermalization occurred. MCT\, on the other hand\, is even more attrac tive because of much longer relaxation times [3]. They are on the ns scale while in graphene thermalization occurs on a timescale of a few ps. The r eason for the longer timescale is the different Landau ladder due to spin splitting. \n\nReferences:\n[1] E. Gornik\, G. Strasser und K. Unterrainer \, Nature Photonics **15**\, 875 (2021).\n[2] M. Mittendorff\, F. Wendler\ , E. Malic\, A. Knorr\, M. Orlita\, M. Potemski\, C. Berger\, W. A. de Hee r\, H. Schneider\, M. Helm und S. Winnerl\, Nature\nPhysics **11**\, (2015 ).\n[3] D. B. But\, M. Mittendorff\, C. Consejo\, F. Teppe\, N. N. Mikhail ov\, S. A. Dvoretskii\, C. Faugeras\, S. Winnerl\, M. Helm\, W. Knap\, M. Potemski und M. Orlita\, Nature Photonics **13**\, 783 (2019).\n\nhttps:// events.ncbj.gov.pl/event/75/contributions/742/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/742/ END:VEVENT BEGIN:VEVENT SUMMARY:Spin and phonon excitations in layered antiferromagnets DTSTART;VALUE=DATE-TIME:20220706T070000Z DTEND;VALUE=DATE-TIME:20220706T074500Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-736@events.ncbj.gov.pl DESCRIPTION:Speakers: Marek Potemski (LNCMI/CNRS and Centera)\nThe results of optical magneto-spectroscopy study (Raman scattering\, THz absorption\ , high frequency magnetic resonance) of layered MnPS3 and FePS3 antiferrom agnets will be presented. Attention will be focused on magneto-elastic in teraction in MnPS3 [1] and appearance of magnon polarons in FePS3 [2]. Bes ides\, the origin of a magnon gap in MnPS3 and splitting of this gap obser ved in both compounds\, will be discussed.\n\n1.Magnetoelastic interaction in the two-dimensional magnetic material MnPS3 studied by first principle s calculations and Raman experiments\nD. Vaclavkova et al.\, 2D Materials 7\, 035030 (2020).\n\n2.Magnon-polarons in van der Waals antiferromagnet FePS3\nD. Vaclavkova et al.\, Phys. Rev. B 104\, 134437 (2021)\n\nhttps:// events.ncbj.gov.pl/event/75/contributions/736/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/736/ END:VEVENT BEGIN:VEVENT SUMMARY:Research potential of the PolFEL facility for THz studies. DTSTART;VALUE=DATE-TIME:20220705T143500Z DTEND;VALUE=DATE-TIME:20220705T151500Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-732@events.ncbj.gov.pl DESCRIPTION:Speakers: Pawel Czuma (NCBJ)\nPolish Free Electron Laser (PolF EL) will be an accelerator based facility\, which will provide researchers THz laser pulses with constant repetition rate of 50kHz. Maximum peak ene rgy of these THz pulse (30µJ) and pulse duration (about 30ps) for such r epetition rates are usually not achievable by typical optical laser source s. This parameters of PolFEL laser THz beam give big research potential in area of THz studies. To help scientists discover this potential\, experi mental station will be equipped with femtosecond pulse laser system: oscil lator\, amplifier and two Optical Parametric Amplifiers (OPA)\, and two re search station: pump-probe (PP) spectrometer and Scattering Nearfield Opti cal Microscope (SNOM). PP spectrometer with aid of two OPA will allow for time-resolved measurements of THz spectra with picosecond time resolution. Synchronization between two lasers: experimental station and photocathode laser\, will allow jitter limitation between THz pulses and optical laser pulses in PP spectrometer. SNOM will allow visualization of specimen in THz beam with sub-micrometer spatial resolution. Together with AFM and FT IR module and with help of IR laser beam from OPA\, SNOM will give researc hers a grate multi-tool for visualization of specimen surface with sub-mic ron spatial resolution in spectral range from mid IR to 1THz. PolFEL facil ity will also provide additional space for scientists with their own equip ment. PolFEL scientists and engineers will help with integration of such e quipment with laser beams available in PolFEL.\n\nhttps://events.ncbj.gov. pl/event/75/contributions/732/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/732/ END:VEVENT BEGIN:VEVENT SUMMARY:Nonlinear response of semiconductor systems under intense THz exci tation DTSTART;VALUE=DATE-TIME:20220705T153500Z DTEND;VALUE=DATE-TIME:20220705T155500Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-720@events.ncbj.gov.pl DESCRIPTION:Speakers: Oleksiy Pashkin (Helmholtz-Zentrum Dresden-Rossendor f)\nIntense narrowband terahertz pulses from the FELBE free-electron laser facility and a complementary table-top high-field THz source are utilized to study nonlinear excitation regimes of various degrees of freedom in se miconductors. In this talk we present several recent examples including im purity transitions in boron doped Si [1]\, intersubband transitions in Ge/ SiGe quantum wells [2] and plasmons in InGaAs nanowires [3\,4].\n\n\n[1] F . Meng et al.\, *Phys. Rev. B* **102**\, 075205 (2020).\n[2] C. Ciano et a l.\, *Optics Express* **28**\, 7245 (2020).\n[3] D. Lang et al.\, *Nanotec hnology* **30**\, 084003 (2019).\n[4] R. Rana et al.\, *Nano Lett.* **20** \, 3225 (2020).\n\nhttps://events.ncbj.gov.pl/event/75/contributions/720/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/720/ END:VEVENT BEGIN:VEVENT SUMMARY:Nonlinear ultrafast studies at TeraFERMI beamline DTSTART;VALUE=DATE-TIME:20220705T113000Z DTEND;VALUE=DATE-TIME:20220705T121500Z DTSTAMP;VALUE=DATE-TIME:20260420T192157Z UID:indico-contribution-75-741@events.ncbj.gov.pl DESCRIPTION:Speakers: Paola Di Pietro (Elettra-Sincrotrone Trieste S.C.p.A . Area Science Park\, SS 14km 163.5 Trieste\, Italy)\nTeraFERMI is a beaml ine built up in 2015 at the Free Electron Laser (FEL) FERMI at Elettra in Trieste (Italy). FERMI is a seeded FEL that works in a single pass-single bunch mode at 10 or 50 Hz\, covering the spectral range from 100 to 4 nm. TeraFERMI is based on a Coherent Transition Radiation source that provides high intense THz electric field in the multi MV/cm range. Such a THz elec tric field can push nonlinear materials well into their nonlinear regime. The beamline experimental setup fulfils the capability to address nonlinea r regime by measuring the fluence-dependent transmission/reflection spectr a or the pump-probe response\, in both the single-colour (THz pump - THz p robe) and the two-colours (THz pump - IR probe) configuration\, even in ex treme conditions (low temperature). Condensed matter is widely investigate d at TeraFERMI: Two-dimensional materials\, Dirac materials\, semiconducto rs\, oxides and superconductors are only some examples. Bio-chemical sampl es\, like water\, can also be studied at the beamlime. Here\, we will focu s mainly on a study carried on a topological insulator\, a particular type of Dirac materials. Topological insulators\, indeed\, show nonlinear THz behaviour similar to the case of graphene\, thanks to the linear dispersio n of their surface Dirac massless carriers. In particular\, we show the no nlinear response of the Dirac plasmon of topological insulator Bi2Se3 thin films.\n[1] Di Pietro P. et al.\, Synchrotron Radiation News\, 30 - 4\, 3 6-39 (2017).\n[2] Di Pietro P. et al.\, Nature Nanotech.\, 8\, 556–560 ( 2013).\n[3] Di Pietro P. et al.\, Phys. Rev. Lett.\, 124\, 226403 (2020).\ n\nhttps://events.ncbj.gov.pl/event/75/contributions/741/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/741/ END:VEVENT END:VCALENDAR