Frequency-tunable terahertz radiation from stimulated polariton scattering in MgO:LiNbO3

Abstract

Stimulated polariton scattering from transverse optical modes in MgO:LiNbO₃ bulk crystals results in generation of electromagnetic waves in the terahertz (THz) region. In this paper, temperature and phase-matching polarization characteristics of MgO:LiNbO₃ are theoretically analyzed. The enhancement of THz gain coefficient at lower temperature is attributed to the decrease in mode linewidth which leads to monotonic reduction in absorption coefficient. The calculated gain of order of several cm^-1 suggests that forward and backward THz waves can be generated using type II non-collinear phase-matching. The results presented in this work will guide new experiments to optimize THz sources based on MgO:LiNbO₃.