A CRITERION FOR APPLYING CHALCOPYRITE SEMICONDUCTORS TO OPTICAL-LINE ELIMINATION FILTERS

The optical fine elimination filter consisting of a birefringent, optically active crystal and two polarizers has a narrow band at the wavelength of the accidental optical isotropy of crystal. Chalcopyrite semiconductors applicable to this filter are predicted from the contribution of anisotropy of transition intensity to birefringence. CuAlS2, AgAlS2, AgAlSe2, AgAlTe2 and AgInS2 are thought to satisfy the condition of the filter, i.e. the accidental optical isotropy. Experimental results show that CuAlS2 had the optical isotropic wavelength at 378 nm. The dependence of center wavelength of AgInxGa1-xSe2 filter on x is estimated from the band parameters. The center wavelength of AgInxGa1-xSe2 filter (x = 0.5) is shown experimentally to be adjusted to the emission line of Nd:YAG laser.