Nonlinear tunable parametric luminescence in ZnGeP 2 crystals

Infrared tunability of parametric superluminescence is studied in ZnGeP2. Q-switched and actively mode-locked Er3+:YSGG laser (2.79 micrometers ) is used to investigate the temperature tunability. Angular tunable wavelength gap near degeneracy in type II phase matching is partially covered by crystal temperature rise thereby eliminating beam walk-off/displacement unavoidable in angular tuning. The result is explained by changes in crystal phonon absorption, birefringence and refractive indices with rise in temperature.