Tm:GdVO_4 microchip laser Q-switched by a Sb_2Te_3 topological insulator

摘要

We report on the first application of a topological insulator based on antimony telluride (Sb_2Te_3) as a saturable absorber (SA) in a bulk microchip laser. The transmission-type SA consisted of a thin film of Sb_2Te_3 (thickness: 3 nm) deposited on a glass substrate by pulsed magnetron sputtering. The saturable absorption of the Sb_2Te_3 film was confirmed for ns-long pulses. The microchip laser was based on a Tm:GdVO_4 crystal diode-pumped at -802 nm. In the continuous-wave regime, this laser generated 3.54 W at 1905-1921 nm with a slope efficiency n of 37%. The Q-switched laser generated a maximum average output power of 0.70 W at 1913 nm. The pulse energy and duration were 3.5 μJ and 223 ns, respectively, at a repetition rate of 200 kHz. The Sb_2Te_3 SAs are promising for passively Q-switched waveguide lasers at -2 μm.