Mode-locked Cr:LiSAF laser far off the gain peak: tunable sub-200-fs pulses near 1 μm

We report, to the best of our knowledge, the first mode-locking results of a Cr:LiSAF laser near the 1 mu M region. The system is pumped only by a single 1.1 W high-brightness tapered diode laser at 675 nm. A semiconductor saturable absorber mirror (SESAM) with a modulation depth of 1.5% and non-saturable losses below 0.5% was used for mode-locking. Once mode-locked, the Cr:LiSAF laser produced almost-transform-limited sub-200-fs pulses with up to 12.5 mW of average power at a repetition rate of 150 MHz. Using an intracavity birefringent filter, the central wavelength of the pulses could be smoothly tuned in the 1000-1020 nm range. Via careful dispersion optimization, pulse widths could be reduced down to the 110-fs level. The performance in this initial study was limited by the design parameters of the SESAM used, especially its passive losses and could be improved with an optimized SESAM design. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

This study reports the first mode-locking results of a Cr:LiSAF laser near the 1 µm region, using a SESAM for mode-locking and generating high-quality sub-200 fs pulses. The pulse characteristics were further improved through dispersion optimization and wavelength tuning.