Rod-type fiber amplifier for pulse compression of high power thin-disk lasers

Abstract

Recent SESAM modelocked thin disk lasers have achieved average powers > 140 W [1] and pulse energies > 25 µJ [2], which is higher than for any other ultrafast oscillator technology. The first demonstrations of power and energy scaling of modelocked thin disk lasers were achieved with the well-established gain material Yb:YAG. However in this case, the achievable pulse duration in high-power operation is limited to ≈700 fs. Many experiments in areas such as high field science require pulse durations in the sub-100-fs regime, which has not been demonstrated with thin disk lasers so far. There are more than ten Yb-doped gain materials that have generated sub-100-fs pulses in standard low-power oscillators, and great efforts are being pursued to extend this performance into the high power regime [3]. Nonlinear pulse compression in passive large mode area (LMA) fiber is an alternative that has proven excellent performance [4, 5]. However, in this approach, pulse energy scaling requires larger mode areas where TEM00 propagation is challenging mainly due to bending and stress issues. An interesting alternative is the use of rod-type fiber amplifier based pulse compressors, where the main amplifier stage accounts for significant SPM spectral broadening [6]. We report here on a pulse compressor for a high-power thin disk laser oscillator based on a LMA rod-type fiber amplifier.