Modeling of the performance of a cryogenic gas cooled Yb:YAG multislab amplifier with a longitudinal doping gradient concentration

Abstract

A cryogenic helium gas cooled Yb:YAG multislab amplifier with a longitudinal doping gradient concentration was proposed for developing high energy, high average power laser systems. As a comparison, the performance of the gradient doped amplifier was investigated with other constant and stepped doped amplifiers in terms of energy storage capacity, heat deposition, and amplification, based on the theory of quasi-three-level laser ions, Monte Carlo, and ray-tracing approaches. Improved lasing characteristics with more homogenous distributions of gain and heat load and higher efficiency was achieved in the gradient doped multislab amplifier while lower gain medium volume was required. It is shown that at the optimum operating temperature of 200 K, the maximum output energy of 867.76 J in the gradient doped amplifier was obtained, corresponding to an optical-to-optical efficiency of 22.41%.