Cr2+:ZnS passively Q-switched Ho:GdTaO4 laser dual end-pumped by the laser diode

Abstract In this paper we present a continuous-wave (CW) and passively Q-switched (PQS) Ho:GdTaO4 (Ho:GTO) laser dual end-pumped by a laser diode at 1.91 μm. Under CW regime, the dual diode-pumped Ho:GTO laser yielded 3.9 W output power and 53.0 % slope efficiency respect to the absorbed pump power. By using the Cr2+:ZnS as a saturable absorber, the average output power of 3.2 W, minimum pulse width of 11.2 ns and pulse repletion rate of 19.78 kHz were achieved. In addition, the beam quality factors (M2) in x- and y-directions of PQS dual diode-pumped Ho:GTO laser were measured to be 1.28 and 1.44, respectively. Moreover, we firstly employed the PQS Ho:GTO laser as the pump source of middle infrared ZnGeP2 optical parametric oscillator (ZGP-OPO). An average output power of 1.3 W was achieved with a slope efficiency of 63.3% in middle infrared ZGP-OPO.