An Improvement of the Cherenkov THz Generation Scheme Using Convex Silicon Prism-Lens Adapters

Abstract

The terahertz (THz) generation efficiency in the Cherenkov optical rectification scheme can be improved significantly if the silicon adaptor, mounted at the lateral surface of a nonlinear crystal, has a convex output surface with proper geometry. We demonstrate and compare with the results of direct experiments a method for theoretically modeling the angular distributions of the spectral power of THz radiation in the case of different Si adaptors, constructed by mounting plano-spherical lenses on a conventional flat Si prism. The applied method of theoretical modeling shows its usefulness in choosing the best Si adapter geometry.

Cascaded Stimulated Polariton Scattering in a Single-Pass KTP Crystal under Picosecond Pumping

“…Such frequency difference points out a process that links all light beams under consideration. The candidate for this process is polariton scattering since the data available from the literature [17][18][19] give also a value of ~188 cm −1 for the polariton frequency in KTP. It seems that the sequence of spectral components observed can be represented as a cascaded SPS process: the pump wave generates the first polariton component, the corresponding Stokes wave generates the second polariton component, etc., with an increasing angle between the wavevector of each subsequent Stokes component and the pump wavevector.…”

“…Ring cavities providing synchronous pumping to obtain SPS in LiNbO 3 crystal by picosecond pulses of 15 ps duration at 80 MHz repetition rate were realized in [14,15]. Femtosecond pulses were also used to generate THz radiation enhanced by phonon polaritons [16][17][18].…”