TY - JOUR AU - Benabdelghani, Imene AU - Tóth, György AU - Krizsán, Gergő AU - Bazsó, Gábor AU - Szaller, Zsuzsanna AU - Mbithi, Nelson AU - Rácz, Péter AU - Dombi, Péter AU - Polónyi, Gyula AU - Hebling, János TI - Three-photon and four-photon absorption in lithium niobate measured by the Z-scan technique JF - OPTICS EXPRESS J2 - OPT EXPRESS VL - 32 PY - 2024 IS - 5 SP - 7030 EP - 7043 PG - 14 SN - 1094-4087 DO - 10.1364/OE.505995 UR - https://m2.mtmt.hu/api/publication/34596731 ID - 34596731 N1 - Szentágothai Research Centre, Ifjúság street 20, Pécs, 7624, Hungary University of Pécs, Ifjúság Street 6, Pécs, 7624, Hungary HUN-REN – PTE High Intensity Terahertz Research Group, Ifjúság Street 6, Pécs, 7624, Hungary Wigner Research Center for Physics, Institute for Solid State Physics and Optics, Budapest, H-1121, Hungary Garissa University, Garissa, Kenya Export Date: 29 April 2024 Correspondence Address: Hebling, J.; Szentágothai Research Centre, Ifjúság street 20, Hungary; email: hebling@fizika.ttk.pte.hu AB - Open-aperture Z-scan measurements have been carried out to investigate the three-photon (3 PA) and four-photon absorption (4 PA) coefficients at 800 nm and 1030 nm wavelengths, respectively in congruent and stoichiometric lithium niobate (cLN, sLN) with different concentrations of Mg doping. The laser pulse duration at the two wavelengths were 40 and 190 fs. The peak intensity inside the crystals varied between approximately 110 and 550 GW/cm 2 . The 3 PA and 4 PA coefficients were evaluated using a theoretical model and the results suggest that their minima are at or around the Mg doping level corresponding to the threshold for suppressing photo-refraction for both cLN and sLN. This result can be attributed to the contribution of crystal defects to the 3 PA and 4 PA processes. Furthermore, the 4 PA at 1030 nm exhibited greater nonlinear absorption than the 3 PA at 800 nm under the same intensity level. Possible reasons for this unexpected behavior are discussed. Overall, comparing the 3 PA and 4 PA values of these crystals will enable for selection of the optimum composition of LN crystal for efficient THz generation and for other nonlinear optical processes requiring high pump intensities. LA - English DB - MTMT ER - TY - JOUR AU - Tóth, György AU - Illés, Gergő AU - Nazymbekov, Gabit AU - Mbithi, Nelson AU - Almási, Gábor AU - Hebling, János TI - Possibility of CO2 laser-pumped multi-millijoule-level ultrafast pulse terahertz sources JF - SCIENTIFIC REPORTS J2 - SCI REP VL - 14 PY - 2024 IS - 1 PG - 8 SN - 2045-2322 DO - 10.1038/s41598-023-51139-4 UR - https://m2.mtmt.hu/api/publication/34494015 ID - 34494015 N1 - Institute of Physics, University of Pécs, Pecs, 7624, Hungary Szentágothai Research Centre, University of Pécs, Pecs, 7624, Hungary Natural Sciences Department, Garissa University, Garissa, 1801, Kenya HUN-REN-PTE High-Field Terahertz Research Group, Pecs, Hungary Export Date: 13 February 2024 Correspondence Address: Tóth, G.; Institute of Physics, Hungary; email: tothgy@fizika.ttk.pte.hu Correspondence Address: Hebling, J.; Institute of Physics, Hungary; email: hebling@fizika.ttk.pte.hu AB - In the last decade, intense research has been witnessed on developing compact, terahertz (THz) driven electron accelerators, producing electrons with a sub-MeV—few tens of MeV energy. Such economical devices could be used in scientific and material research and medical treatments. However, until now, the extremely high-energy THz pulses needed by the THz counterparts of the microwave accelerators were generated by optical rectification (OR) of ultrafast Ti:sapphire or Yb laser pulses. These lasers, however, are not very effective. Because of this, we use numerical simulations to investigate the possibility of generating high-energy THz pulses by the OR of pulses produced by CO2 lasers, which can have high plug-in efficiency. The results obtained supposing optical rectification (OR) in GaAs demonstrate that consideration of the self-phase-modulation (SPM) and the second-harmonic-generation (SHG) processes is indispensable in the design of CO2 laser-based THz sources. More interestingly, although these two processes hinder achieving high laser-to-THz conversion efficiency, they can still surpass the 1.5% value, ensuring high system efficiency and making the CO2 laser OR system a promising THz source. Our finding also has important implications for other middle-infrared laser-pumped OR-based THz sources. LA - English DB - MTMT ER - TY - CHAP AU - Polónyi, Gyula AU - Tóth, György AU - Mbithi, Nelson AU - Tibai, Zoltán AU - Benabdelghani, Imene AU - Nasi, Luis AU - Krizsán, Gergő AU - G., Illés AU - Hebling, János TI - Investigation of Terahertz Pulse Generation in Semiconductors Pumped at Long Infrared Wavelengths T2 - 2023 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) PB - IEEE CY - Online kiadás SN - 9798350345995 PY - 2023 DO - 10.1109/CLEO/EUROPE-EQEC57999.2023.10231383 UR - https://m2.mtmt.hu/api/publication/34417852 ID - 34417852 N1 - ELKH-PTE High Intensity Terahertz Research Group, Pécs, 7624, Hungary Szentágothai Research Centre, Pécs, 7624, Hungary University of Pécs, Pécs, 7624, Hungary Garissa University, Department of Natural Sciences, Garissa, Kenya Conference code: 192392 Export Date: 6 December 2023 AB - Recently, there has been a surge in developing highly efficient, scalable, and compact THz sources with high pumping energy for research in particular in biology, medicine, or particle acceleration. Among various approaches, THz generation by optical rectification (OR) provides an effective and tabletop solution for THz pulses flexibly tailored to the mentioned needs. Up to now, high energy in the low frequency THz regime was reached in LN (1.4 mJ) [1], and in the DSTMS organic crystal (0.9 mJ) [2]. While the former suffers several significant limitations which reduce the efficiency below 1%, the latter has, as all organic nonlinear crystals do, a low damage threshold, hindering its practical use. ZnTe has already been proven to be an efficient source when the low-order multiphoton absorption is suppressed [3], and shows that semiconductors can potentially be good candidates for efficient, high-energy THz sources when pumped at longer wavelength. © 2023 IEEE. LA - English DB - MTMT ER - TY - CHAP AU - Benabdelghani, Imene AU - Tóth, György AU - Krizsán, Gergő AU - Mbithi, Nelson AU - Bazsó, Gábor AU - Rácz, Péter AU - Dombi, Péter AU - Hebling, János AU - Polónyi, Gyula TI - Three-photon and Four-photon Absorption in Lithium Niobate and Lithium Tantalate by Z-scan Technique T2 - 2023 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) PB - IEEE CY - Online kiadás SN - 9798350345995 PY - 2023 PG - 1 DO - 10.1109/CLEO/Europe-EQEC57999.2023.10232756 UR - https://m2.mtmt.hu/api/publication/34167389 ID - 34167389 LA - English DB - MTMT ER - TY - GEN AU - Balázs, Sarkadi AU - Turnár, Szabolcs AU - Kiss, Mátyás AU - Mátyás, Reményi AU - Anna, Bereghszászy AU - Almási, Gábor AU - Hebling, János AU - Tibai, Zoltán TI - Kompakt terahertzes részecskegyorsító elrendezés = Table-top THz-based electron accelerator setup PY - 2023 UR - https://m2.mtmt.hu/api/publication/33872930 ID - 33872930 N1 - Előadás LA - English DB - MTMT ER - TY - JOUR AU - Mukherjee, Deshabrato AU - Kalas, Benjamin AU - Burger, Sven AU - Sáfrán, György AU - Serényi, Miklós AU - Fried, Miklós AU - Petrik, Péter TI - Nanostructures for in-situ surface-enhanced Kretschmann-Raether ellipsometry JF - PROCEEDINGS OF SPIE - THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING J2 - PROCEEDINGS OF SPIE VL - 12428 PY - 2023 SP - 206 EP - 214 PG - 9 SN - 0277-786X DO - 10.1117/12.2649080 UR - https://m2.mtmt.hu/api/publication/33699389 ID - 33699389 LA - English DB - MTMT ER - TY - THES AU - Csajbók, Viktória TI - Ultrarövid lézerimpulzusok kölcsönhatása dielektrikumközegekkel PY - 2023 UR - https://m2.mtmt.hu/api/publication/33685028 ID - 33685028 LA - Hungarian DB - MTMT ER - TY - THES AU - Varga-Umbrich, Károly TI - Többfotonos adiabatikus átmenetek alkalmazása rubídium atomok koherens gyorsítására PY - 2023 SP - 88 UR - https://m2.mtmt.hu/api/publication/33685022 ID - 33685022 LA - Hungarian DB - MTMT ER - TY - JOUR AU - Kacskovics, Balázs AU - Barta, Dániel AU - Vasúth, Mátyás Zsolt TI - Rapidly rotating neutron stars with realistic nuclear matter equation of state JF - ASTRONOMISCHE NACHRICHTEN J2 - ASTRON NACHRICH VL - 344 PY - 2023 IS - 1-2 PG - 6 SN - 0004-6337 DO - 10.1002/asna.20220109 UR - https://m2.mtmt.hu/api/publication/33585088 ID - 33585088 N1 - Export Date: 08 March 2024 AB - We performed the comparison of three different numerical codes for constructing equilibrium models; (I) a code for static equilibrium configurations, (II) an implementation of the Hartle-Thorne slow-rotation approximation, (III) a numerical solution of the full Einstein equations by LORENE. We aimed to construct sequences of uniformly rotating configurations at various rotation frequencies up to the Keplerian frequency for a hybrid hadronic-quark matter EOS where a smooth transition is provided between two separate phases. We investigated the difference between the results computed by the implementation of Hartle-Thorne slow-rotation approximation and by LORENE/nrotstar, respectively. We have concluded that the codes can increase the difference between the slow-rotating and the fast-rotating approach exponentially, reaching 6.67% for the maximal mass configuration rotating at the Keplerian frequency. LA - English DB - MTMT ER - TY - THES AU - Jakab, David TI - The Interplay of Unitary and Permutation Symmetries in Composite Quantum Systems PY - 2022 SP - 135 UR - https://m2.mtmt.hu/api/publication/33683934 ID - 33683934 LA - English DB - MTMT ER -