Self-Q-switched operation in Tm:YAG crystal and passively Q-switched operation using GaSe saturable absorber

Abstract

In this paper, we investigated the self-Q-switched (SQS) operation in Tm:YAG crystal. The diode-pumped SQS Tm:YAG laser was operated at a central wavelength of 2006 nm. With the pump power of 4.4 W, we got two sets of data: (1) the optical conversion efficiency of the SQS operation with output coupler (OC) of 10% was 12.50%, and the corresponding output power was 0.55 W; (2) the optical conversion efficiency of the SQS operation with OC of 15% was 19.77%, and the corresponding output power was 0.87 W. Thus, Tm:YAG crystal could be widely used in SQS lasers. In addition, GaSe saturable absorbers (SAs) with broadband nonlinear saturable absorption properties were fabricated and employed as SAs for passively Q-switched Tm:YAG lasers. Attributing to the weak evanescent field and long interaction length, GaSe SAs could work at high-power regime and wide-wavelength range. In summary, GaSe is a good 2D SA material in wide-wavelength range.