ZGP OPO with a 3.8-12.4 /spl mu/m tunability

Summary form only given.Accessing wavelengths beyond 4 microns presents a technical challenge, however newly developed nonlinear optical crystals such as ZnGeP/sub 2/ (ZGP) make it possible to build a practical frequency converter that is tunable in the 3-12 /spl mu/m wavelength range thus covering both atmospheric windows. The high nonlinear-optical coefficient (d/sub eff/=75 pm/V) and broad IR optical transparency (2-12 /spl mu/m) favor a variety of nonlinear optical applications of ZGP, including OPOs and OPGs. We report on an efficient ZGP OPO with unprecedented tunability of 3.8-12.4 /spl mu/m, having narrow (less than 0.5 cm/sup -1/) linewidth and less than 1 mJ pump threshold, which can be a basis for a new spectroscopic tool.