A new ternary chalcogenide crystal for nonlinear optical applications in the mid-infrared:LiInSe{sub}2

摘要

The effective nonlineary of LiInSe{sub}2 is comparable to that of AgGaS{sub}2. The most interesting interaction scheme for LiInSe{sub}2 is eo-e (or oe-e) for propagation in the x-y plane. In uniaxial Crystals with the chalcopyrite structure the effective nonlinearity vanishes in the 900-limit of noncritical type-II interaction. As a consequence in the case of AgGaS{sub}2 the only possible type-I noncritical interaction is very limited at room temperature: the shortest wavelength (the pump wavelength in down conversion processes) should lie below ≈900 nm (below ≈700 nm to obtain mid-IR wavelengths above 5 μm) which rules Out the application of the widely spread powerful laser sources in the 1 μm specral range. The mm2 symmetry of LiInSe{sub}2 offers the possibility for noncritical type-II interaction for any pump wavelength and in particular 1 μm, the limits being set only by the transparency window of the crystal. In addition preliminary measurements indicate that LiInSe{sub}2 might have 4-5 times better thermal conductivity than AgGaS{sub}2.