Modeling of amplified spontaneous emission, heat deposition, and energy extraction in cryogenically cooled multislab Yb^3+:YAG laser amplifier for the HiLASE Project

A three-dimensional ray-tracing code for determination of amplified spontaneous emission in a multislab laser amplifier is presented. In addition to energy stored in the amplifier, the code also calculates the heat distribution and the amplification of the signal beam. For cryogenically cooled multislab amplifiers with Yb3+:YAG and absorptive Cr4+:YAG cladding, energy storage efficiency greater than 52% and small signal gain of 22  m−1 were obtained. The pump energy converted to heat was found to be 11% in the active volume and 50% in the Cr4+:YAG cladding.