EXTRA-WIDE TUNING RANGE OPTICAL PARAMETRIC GENERATOR

Mid-infrared radiation, continuously tunable in the range 3.3-19 mu m was achieved using double-pass travelling-wave optical parametric gene rator (OPG) based on GaSe crystal. This is the largest wavelength rang e of tunability, ever obtained with parametric generators/oscillators. The OPG was pumped by single pulses of an actively mode-locked, Q-swi tched and cavity dumped Er:Cr:YSGG laser (lambda = 2.8 mu m) with the pump threshold of 1.1 GW/cm(2) for a L = 1.4 cm GaSe crystal. New resu lts on the ZnGeP2 OPG, having smaller tunability, but lower pumping th resholds and higher efficiency, due to ZnGeP2 higher nonlinearity, are also reported.