Scaling the mid-IR radiation at 7 μm - Two-stage double-pass 195 MHz narrow-bandwidth DFG laser system

We present a laser system based on difference frequency generation (DFG) to produce tunable, narrow-linewidth (<30 pm), and high-energy mid-IR radiation in the 6785 nm region. The system exploits nonlinear crystals (such as LiInS2, LiInSe2 and BaGa4Se7) and nanosecond pulses generated by single-frequency Nd:YAG and Cr:forsterite lasers at 1064 and 1262 nm, respectively. Various experimental configurations are used: single-pass and double-pass through the nonlinear crystal. Additional increments of the output energy can be obtained by performing two stage double-pass geometry.