Passively mode-locked diode-pumped Tm$^{3+}$ :YLF laser emitting at 1.91 $\mu$m using a GaAs-based SESAM

Abstract : We report on a diode-pumped Tm:YLF laser passively mode-locked with an InGaAs saturable absorber. The laser emits a train of 31 ps pulses at a wavelength of 1.91 $\mu$m with a repetition rate of 94 MHz and a maximum average power of 95 mW. A sustained and robust mode-locking with a signal-to-noise ratio of ~70 dB is obtained even at high relative air humidity, making this system attractive for applications requiring ultra-short pulses in the spectral window just below 2 $\mu$m.