A kilohertz nanosecond 1645 nm KTA-OPO pumped by a 1064 nm pulse laser for methane detection

In this Letter, we studied a kilohertz nanosecond 1645 nm optical parametric oscillator (OPO) for methane detection.The OPO pump source was an electro-optical Q-switched 1064 nm oscillator, followed by a preamplifier and two Innoslab amplifiers.Two KTiOAsO 4 crystals with type II angular phase matching were used as the nonlinear working materials, and two plane mirrors were used for the OPO cavity.We achieved the signal light with an average power of 9.32 W and a minimum pulse duration of 1.8 ns at a repetition rate of 8 kHz for a 54.1 W pump power, and the optical-optical conversion efficiency was 17.3%.The beam quality was measured as M x 2 = 1.08 and M y 2 = 1.22.The wavelength of the signal light was continuously tunable from 1641.9207 to 1648.1791 nm.To the best of our knowledge, this is the highest average power achieved at the kilohertz regime of a 1645 nm laser.