Stable continuous-wave mode-locked laser from a 1645 nm Er:YAG ceramic oscillator

Abstract We demonstrate stable continuous-wave mode-locking (CWML) pulses around 1645 nm by employing a homemade Er:YAG ceramic. By using a fiber laser and semiconductor saturable absorber mirror (SESAM) with a modulation depth of 1.2%, we get ML pulses with an output average power up to 815 mW, a pulse width shortened as ∼4 ps, and a peak power of ∼1.8 kW. With the SESAM of the modulation depth of 2.4%, second-order harmonic ML pulses were also obtained. As far as we know, this is the first report of CWML from Er 3+ -doped ceramics and also the shortest pulse duration in Er 3+ -doped solid-state oscillators.