CW and passive Q-switching of 1331-nm Nd:GGG laser with Co2+:LMA saturable absorber

In this paper, the output performances at 1331 nm in continuous-wave (CW) operation and the passive Q-switching regime of a Nd:Gd3Ga5O12(Nd:GGG) laser crystal have been investigated under pumping with diode lasers. A maximum CW output power of 1.5 W was reached at an incident pump power of 7.5 W; the overall optical-to-optical efficiency and the slope efficiency with respect to the pump power were 21.5% and 19.4%, respectively. The passive Q-switching regime was achieved with Co2+:LaMgAl11O19 (Co2+:LMA) saturable absorber (SA) crystals. A maximum average output power of 183 mW was recorded with a Co2+:LMA SA with initial transmission T (i) of 90%. The pulse energy was 18.7 mu J and the pulse duration was 26.1 ns, which correspond to a pulse peak power of 0.7 kW. With a Co2+:LMA SA with T (i)=81%, the average power decreased to 131 mW. However, the pulse energy increased to 21.4 mu J, the pulse duration was 16.4 ns and the pulse peak power increased to 1.3 kW.