Watt-level widely tunable narrow-linewidth pulsed mid-infrared MgO:PPLN optical parametric oscillator with a F-P etalon

A watt-level, widely tunable, narrow-linewidth pulsed MgO:PPLN optical parametric oscillator using a single etalon is demonstrated above 3 µm for the first time, to the best of our knowledge. The pump source is an acousto-optical Q-switched Nd:YAG laser at 1064 nm with a pulse duration of 220 ns and a repetition rate of 10 kHz. Employing a V-shaped cavity configuration, the emission wavelengths of the OPO can be tuned in the range of 3.64 µm − 3.8 µm and 1478 nm − 1503 nm by varying the temperatures of the MgO:PPLN crystal between 37℃ and 146℃. Under a pump power of 22.5 W, a maximum average output power of 2.12 W at 3.74 µm is achieved with a theoretical linewidth of 0.3 nm at the temperature of 79.6℃, corresponding to a pulse width of 145 ns and a peak power of 1.46 KW. At the same time, a maximum signal power of 2.86 W at 1486.66 nm is obtained with a linewidth of 0.03 nm, corresponding to a pulse width of 190 ns and a peak power of 1.51 KW.