Hundred watt level and high energy compact hybrid fiber femtosecond laser with good beam quality

Abstract

A hundred watt level compact femtosecond laser system comprised of a high gain, low nonlinearity silicate glass fiber amplifier and a highly efficient Yb:YAG single-crystal fiber amplifier is demonstrated. By reducing the harmful thermal lens effect of amplifiers and optical elements, and precisely tuning dispersion of the stretcher, 110 W, 495 fs laser output at 1 MHz repetition rate and 250 μJ, 494 fs laser output at 200 kHz repetition rate are obtained. An optimized beam-quality factor (M 2) of better than 1.3 is obtained by filtering the beam with a small-aperture diaphragm. To our best knowledge, this is the first demonstration of such a hybrid femtosecond laser over 100 W and 100 μJ with good beam quality.