Mid-infrared laser source - operators guide

A mid-infrared laser source, based on an optical parametric oscillator pumped by a Nd:YVO4 laser at 1.06 μm wavelength, is described. The nonlinear material is periodically-poled lithium niobate (PPLN). The source operates at 20 kHz pulse rate, and the idler wavelength is tunable across the 3.1-3.8 μm region, using 8 different PPLN grating periods on a single crystal. The idler output power is in the range of 1.1-1.4 W, depending on the wavelength, and the corresponding pump-to-idler conversion efficiency is 7-9 %. The beam quality of the idler, given by the M2-value, is in the range of 1.3-1.7, which is slightly poorer than that of the pump. In addition to describing the laser source and its characteristics, the report also serves as a guide for operation of the system.