Characteristics of terahertz-wave generation from GaSe crystals

Terahertz (THz) waves from 0.3 to 4.9 THz were generated from GaSe by difference-wave generation using a YAG laser and an optical parametric oscillator. The spectral THz intensity distribution matched the spectrum of the THz absorption coefficient well, which suggested the effect of imperfections in the crystal. The fairly narrow beam profile and narrow line width, together with the simplicity of the collinear configuration, make GaSe an effective THz-wave generator. It is compared with a GaP THz-wave generator.