Semiconductor compounds: growth and application in nonlinear optics

The results of 25 years of development of ternary and binary semiconductor nonlinear CdGeAs/sub 2/, ZnGeP/sub 2/, AgGaSe/sub 2/, Tl/sub 3/AsSe/sub 3/, GaSe crystal growth, doping and post growth treatment technologies, are summarized. Special attention has been paid to doped ZnGeP/sub 2/, GaSe and mixed AgGa/sub x/In/sub 1-x/Se/sub 2/, Ga/sub x/In/sub 1-x/Se crystals. The crystals grown are O20/spl sim/30/spl times/60/spl sim/100 mm in size and had absorption coefficients of /spl alpha//spl les/0.01 cm/sup -1/ at maximal transmission range. Post growth treatment techniques were developed to decrease optical losses in ZnGeP/sub 2/ crystals at the so called short-wavelength absorption "shoulder". An analogous effect was reached by in-growth doping. The hardness of extra soft GaSe crystals was reached by In doping that gave the possibility to cut it with a diamond saw at any orientation and to polish. In addition good layer cohesion resulted in naturally high levels (about 70 pm/V) of second order nonlinear susceptibility. It was confirmed experimentally for the first time the possibility of 90/spl deg/ phase-matching in mixed crystals, in particular in AgGa/sub x/In/sub 1-x/Se/sub 2/ crystals. A large variety of near, middle and far IR harmonic, sum and difference frequency converters with efficiencies up to 80%, as well as broadband (/spl Delta//spl lambda/=3.9-10 /spl mu/m) and efficient OPOs were realized.