Silver Gallium Selenide Infrared Nonlinear Crystals

   AgGaSe₂(AGSe) has been demonstrated to be an efficient frequency doubling crystal for infrared radiation such as the 10.6 um output of CO2 laser. It has also been shown to be an excellent crystal for nonlinear three-wave interactions. With suitable pump lasers, AGSe optical parametric oscillator (OPO's) can produce continuously tunable radiation over a wide range of wavelengths in the infrared.
   This crystal has a high nonlinear coefficient, high damage threshold, and a wide transmission range. It also has low optical absorption, low scattering and low wavefront distortion. Among commercially available crystals, AGSe has the highest figure of merit for nonlinear interactions in the near and deep infrared. The availability of this crystal has stimulated new activities exploiting its many interesting properties. Potential applications include wavelength selectable medical procedures, LIDAR, a solid-state equivalent of an IR dye laser, and a wide variety of spectro-scopic applications. It is useful for high performance IR waveplates.
   AgGaSe₂ has band edges at 0.73 and 18 um .Its useful transmission range laying within 0.9-16um; Its wide phase match ability provides excellent potential for OPO applications when pumped by variety of currently available lasers. Turning within 2.5-12um was obtained when pumped by Ho:YLF laser at 2.05um, NCPM operation within 1.9-5.5um was achieved pumped at 1.4-1.55um; Efficient SHG CO2 laser has been demonstrated. The output range can be extended by sum or difference frequency mixing (SFM/DFM).
   AgGaS₂(AGS) is transparent from 0.53 to 12um, Its high short wavelength transparency edging at 550nm has been used in OPOs pumped by Nd:YAG Laser, in numerous difference frequency mixing experiments using diode, Ti:Sapphire, Nd:YAG and IR dye lasers covering 3-12 um range; direct infrared counter measure systems, and SHG of CO2 laser.