CC BY
4*
ALT'23
The 30th International Conference on Advanced Laser Technologies
N-I-6
Terahertz stimulated emission from the molecular crystals
V.Kovalev1, A.Sinko2, A.Shkurinov3
1-Lebedev Physical Institute, Russian Academy of Sciences Leninskii Prospect 53, Moscow 119991, Russia 2- ILIT RAS-Branch of the FSRC "Crystallography and Photonics", RAS, 140700 Shatura, Moscow Region, Russia; 3- Faculty of Physics, Lomonosov Moscow State University, 119991 Moscow, Russia;
Main author email address: [email protected]
The growth in the number of methods and devises for generation terahertz (THz) radiation and improvement of their performance are essential for the progress of THz science and technology. In the recent years THz radiation below 3 THz realized with a reasonably high efficiency in the range of widegap solid crystals like GUHP, under the irradiation of femtosecond near-IR laser pulses. Typical for such sources is a single-cycle THz splash at the very beginning of generated pulse, and the prolonged oscillation radiation, the frequency of which corresponds to the frequency of a Raman active mode(s) in the samples. While the splash accounted for in terms of the optical rectification of pump radiation, the prolonged oscillation attributed to the dipole emission by coherent phonons generated in an optically transparent solid medium when a sufficiently short laser pulse passes through the phenomenon was called the impulsive stimulated Raman scattering (ISRS)). Their THz radiation is possible because the correspondent phonon modes are both Raman and infrared active. The present talk studies narrow-band terahertz (THz) emission stimulated by femtosecond laser pulse in molecular crystal guanylurea hydrogen phosphite (GUHP). We demonstrate that this emission is closely connected with the excitement of high-quality phonon oscillations in the crystal, which is proved by the temperature dynamics of the spectra and DFT calculations. For the purposes of studying the origin of this stimulated THz emission and creation of the adequate model of the phenomenon, we analyzed the polarization sensitive spectra of spontaneous Raman scattering and THz transmission spectra while considering their polarization features in relation to crystallographic axes of GUHP crystal. In this paper we show that molecular crystals provide an effective means to convert vis-NIR laser light regardless of wavelength into the THz frequency range. This approach can lead to the creation of "laser-like" source with the desired THz frequency for a range of medical, scientific, and technological applications.
