Optical breakdown threshold of nonlinear GaSe and GaSe:In crystals at a wavelength of 2.1 microns

The paper defines the laser-induced damage threshold from the fluence and the peak power of GaSe and GaSe:In single crystals upon exposure to nanosecond radiation in the two-micron range and assesses the influence of test radiation energy parameters (pulse repetition rate, pulse duration) on the damage threshold. Laser-induced damage threshold was determined with the parameters of the incident radiation close to the pump radiation parameters of promising dual-wavelength optical parametric oscillators (effective pump sources for THz difference frequency oscillators): wavelength is ~ 2.1 μm, pulse repetition rate is 12 and 20 kHz, pulse duration is 18-22 ns.