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2Narrowband terahertz sources based on the molecular crystals and metasurface terahertz filters
A. Sinko1'2'3*, N. Kozlova1, V. Manomenova1, M. Konnikova1'2'3, A. Shkurinov1'2'3
1- NRC Kurchatov Institute, Moscow, Russia 2- Faculty of Physics, Lomonosov Moscow State University, Moscow, Russia 3- Laboratory of Laser Molecular Imaging and Machine Learning, Tomsk State University, Tomsk, Russia
Previously in [1,2] we demonstrated the possibility of creating a coherent high-quality source of narrowband terahertz radiation on the basis of GUHP molecular crystal, for which NIR single ultrashort laser radiation pulses act as pumping. This phenomenon is set up by the second-order nonlinear optical processes, Raman and IR activity of phonon oscillations of the molecular crystal lattice.
Narrowband terahertz radiation generation was achieved for the first time in molecular crystals of phthalic acid salts (C6H4COOHCOOM, M=Na,K,Rb) NaAP, KAP, RbAP and in a sucrose crystal (C12H22O11). At cryogenic temperatures, the femtosecond laser pumped molecular crystals act as effective narrowband terahertz sources due to the good localization of molecular vibrations. The obtained terahertz radiation spectra for KAP crystal are presented in Fig. 1.
Frequency 1
Fig. 1: Spectra of generated in KAP terahertz radiation.
Since the obtained series of narrowband sources have several generation lines in the range of 0.2-3 THz, the use of metasurfaces as terahertz radiation filters [3] was proposed to isolate individual narrow spectral emission lines. This approach is also promising due to the possibility of controlling the transmission of such filters by changing their parameters with external excitation [4].
This work was carried out within the state assignment of NRC "Kurchatov Institute" in part of terahertz generation experiments, was supported by the Ministry of Science and Higher Education of the Russian Federation (Grant No. 075-15-2021-1353) in part of sample preparing and characterization, by the Ministry of Science and Higher Education of the Russian Federation (the grant No. 075-15-2024533) in part of sample spectroscopic characterization, and by the Tomsk State University Development Program (Priority-2030) in part of theoretical investigation.
[1] A. Sinko, et al, A monoclinic semiorganic molecular crystal GUHP for terahertz photonics and optoelectronics, Scientific reports 11.1 (2021): 23433.
[2] A.S. Sinko, et al, Polarization sensitive Raman scattering and Stimulated terahertz emission from GUHP molecular crystal, IEEE Transactions on Terahertz Science and Technology 13.5 (2023): 526-538.
[3] L. Wang, et al, A review of THz modulators with dynamic tunable metasurfaces, Nanomaterials 9.7 (2019): 965.
[4] M.R. Konnikova, et al, GeTe2 phase change material for terahertz devices with reconfigurable functionalities using optical activation, ACS Applied Materials & Interfaces 15.7 (2023): 9638-9648.
