High-power Yb:YAG thin-rod amplifier for use in a regenerative amplifier based on dual-slab Yb:KGW crystals

We present a hybrid chirped pulse amplification femtosecond laser amplification system with which to realize a Yb:KGW regenerative amplifier (RGA) and a Yb:YAG thin-rod amplifier. The combination of RGA based on dual Yb:KGW crystals and a thin-rod Yb:YAG amplifier with a high gain brings about output power up to 46 W before and 29.2 W after pulse compression down to 277 fs at a repetition rate of 200 kHz. The gain-narrowing effect was complemented by a combination of different types of gain-medium amplification. The results show that the output power of a Yb:KGW-based amplifier can be amplified simply by using a Yb:YAG thin-rod amplifier while suppressing the broadening of the pulse duration by gain narrowing.