High-power widely tunable singly resonant optical parametric oscillator based on PPLN or MgO-doped PPLN

Abstract

Tunable near-infrared and mid-infrared radiations have drawn enormous interest and obtained a variety of applications, such as, molecular analysis, remote sensing, laser radar, material spectroscopy, air pollution detection and so on. The periodically poled lithium niobate (PPLN) crystal is a suitable material to realize the infrared solid-state lasers. A QPM singly resonant OPO based on PPLN crystal is experimentally demonstrated and the measured results are reported in this paper. The OPO system is pumped by a commercial acousto-optically Q-switched Nd:YAG laser. Its output wavelength is 1.064 μm, pulse duration of 150 ns at a repetition rate of 10 kHz. A maximum laser output power of 1.23W at the idler wavelength of 3.09 μm has been obtained for the OPO when the pump power is 8.15 W. And now the optic - optic conversion efficiency is 15.1%. The widely tunable mid-infrared ranges of 2.80-3.17 μm, 3.34-3.60 μm, 3.77-3.97 μm, 4.15-4.32 μm, and 4.48-4.62 μm are obtained by changing both the crystal's temperature from 40 to 200 °C and grating periods from 26.5 μm to 30.5 μm. A QPM singly resonant OPO based on MgO-doped PPLN crystal is experimentally demonstrated and the measured results are presented in this paper, too. The pump source is also the acousto-optically Q-switched Nd:YAG laser. A maximum laser output power of 2.17 W at the idler wavelength of 3.33 μm has been obtained for the OPO when the pump power is 8.15 W. And now the optic - optic conversion efficiency is 26.7%. The tunable mid-infrared ranges are 2.83-2.89 μm, 3.10-3.38 μm, 3.57-3.78 μm, 3.95-4.12 μm, 4.28-4.46 μm, and 4.65-4.79 μm. Compared to PPLN crystal, we can obtain higher idler output power and optic - optic conversion efficiency by using MgO-doped PPLN crystal.