Effects of gain saturation on terahertz radiation via optical difference frequency generation

Numerical studies on stability of terahertz (THz) radiation generation based on difference frequency generation in nonlinear crystals are reported. When the gain saturation is achieved at a wavelength that corresponds to an optimal crystal length, the maximal output of THz radiation could be obtained. As a result of crystal absorption, the gain saturation region of THz radiation is unstable region for output. The stability of THz radiation is determined by the stability of pump in the stable region where behind of the gain saturation.