[21a-S611-11~20] 3.5 Laser system and materials

[21a-S611-11] A model development for quantitative analysis of CW regime, multi-pass amplifier system characteristics including optical losses

〇Haik Chosrowjan¹, Toshiyuki Kitamura¹, Seiji Taniguchi¹, Masayuki Fujita¹, Yasukazu Izawa¹ (1.Inst. for Laser Tech)

Keywords:laser amplifier modelling,cryogenic laser,Yb:YAG medium

Powerful CW lasers with high brightness and good beam quality are increasingly required for many applications. We are developing a multi-pass, LD pumped MOPA amplification system based on cryogenically cooled Yb:YAG TRAM (total - reflection active mirror) laser medium. For quantitative analysis of the MOPA system characteristics and parameter optimization (pump- and seed-beam profiles, beam sizes etc.), a quantitative model describing the amplification process including system losses, is very desirable. In our previous contribution, we have presented a simple model based on the Frantz-Nodvik approximate analytical expression and effective average small signal gain coefficient for flattop pump/seed beams. In the present contribution, we will present and discuss a linear model which can take into account also the pump/seed beam profiles and incurred linear optical losses by the system. Some calculation results and predictions for multi-pass MOPA including pump/seed beam shapes and linear optical losses will be presented.