Compact 20-pass thin-disk amplifier insensitive to thermal lensing

摘要

We present a multi-pass amplifier which passively compensates for distortions of the spherical phasefront occurring in the active medium. The design is based on the Fourier transform propagationwhich makes the output beam parameters insensitive to variation of thermal lens effects in the activemedium. The realized system allows for 20 reflections on the active medium and delivers asmall-signal gain of 30 with M~2 = 1.16. Its novel geometry combining Fourier transformpropagations with 4f-imaging stages as well as a compact array of adjustable mirrors allows for alayout with a footprint of 400 mm x 1000 mm.