ИСТИНА

Previously 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 (C6H4COOH·COOM, 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.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 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.