Generation of tunable coherent nanosecond 8-12um mid-infrared pulses based on difference frequency generation in GaSe and ZnGeP_2

摘要

Based on the theoretical analysis on the phase-matching relations, effective nonlinear coefficients, walk-off and acceptance angles, the generation of tunable and coherent nanosecond mid-infrared radiation covering the 8-12um range is realized by use of difference frequency generation (DFG) in a GaSe and a ZnGeP_2 (ZGP) crystal. Using an 8-mm-long GaSe crystal, we achieve the mid-infrared generation that is continuously tunable from 8.28μm to 18.365μm. The maximum pulse energy is 31 μJ at 8.76μm, corresponding to the conversion efficiency of 0.9% and the maximum mid-infrared peak power of about 7kW. In the case of using an 8-mm-long ZGP crystal, the tuning range is from 7.2um to 12.2um. The maximum pulse energy is about lOuJ at 9.22um, corresponding to the conversion efficiency of 0.45% and the peak power of 2.2kW.