Refractive Index Measurements and New Sellmeir Coefficients of Zinc Germanium Phosphide From 2-9 Microns With Implications for Phase Matching in Optical Parametric Oscillators

Recent experiments in mid IR frequency conversion have revealed that older Sellmeir models for zinc germanium phosphide are inadequate. Erroneous predictions in phase matching angles based on older refractive index data have resulted in compromised device performance. We have conducted a complete study of the refractive indices of zinc germanium phosphide from 2 to 9 microns and calculated new Sellmeir coefficients. We have used these to explain the results of recent experiments with mid IR optical parametric oscillators. The phase matching calculations based on our new refractive index data predict much more closely the results of several different mid IR frequency conversion experiments.