Verification of an integral figure of merit for mid-IR nonlinear crystals

The examination and verification of a simple integral figure of merit for nonlinear crystals, taking into account different crystal properties, was studied. The examination was carried out on the basis of experimental data on the broadband sum frequency generation of CO laser radiation in , , , GaSe, and mid-IR nonlinear crystals. Taking into account spectral and angular phase-matching bandwidths, the figure of merit provides the best agreement with the experiment and can be applied for qualitative, and even quantitative, comparison of the nonlinear crystals.