Terahertz generation in Czochralski-grown periodically poled Mg:Y:LiNbO3 by optical rectification

Abstract

Using a canonical pump-probe experimental technique, we studied terahertz (THz) wave generation and detection by optical rectification and mixing in Czochralski-grown periodically poled Mg:Y:LiNbO3 (PPLN) crystals. THz waves with frequencies at 1.37 and 0.68 THz as well as 1.8 THz were obtained for PPLN with nonlinear grating periods of 30 and 60 µm, respectively. A general theoretical model was developed by considering the dispersion and damping of a low-frequency phonon-polariton mode. Our results show that THz waves are generated in forward and backward directions by pumping pulse rectification. The generated THz waves depend on the spectral shape of the laser pulses, quasi-phase mismatches, and dispersion characteristics of a crystal.