Saturation of the gain of 0.3–30 nsec laser pulses in phosphate neodymium glasses

An investigation was made of saturation of the gain in GLS21 and OPS3106 phosphate neodymium glasses. It was found that the gain may be accurately described by the Franz-Nodvik equation in which the saturation energy density W_s depends on the type of glass and the energy density and does not depend on the polarization of the radiation. The efficiency of energy extraction from the active medium was found to be around 60% and it was found that this may be increased at least to 70%. It was established that for a pulse duration τ_p = 1–30 nsec, W_s does not depend on τ_p, whereas when τ_p < 1 nsec, it decreases slowly with decreasing τ_p. Empirical formulas were derived to calculate the radiation energy and its extraction efficiency.