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

The optical fine elimination filter consisting of a birefringent, opti cally active crystal and two polarizers has a narrow band at the wavel ength of the accidental optical isotropy of crystal. Chalcopyrite semi conductors applicable to this filter are predicted from the contributi on of anisotropy of transition intensity to birefringence. CuAlS2, AgA lS2, AgAlSe2, AgAlTe2 and AgInS2 are thought to satisfy the condition of the filter, i.e. the accidental optical isotropy. Experimental resu lts show that CuAlS2 had the optical isotropic wavelength at 378 nm. T he dependence of center wavelength of AgInxGa1-xSe2 filter on x is est imated from the band parameters. The center wavelength of AgInxGa1-xSe 2 filter (x = 0.5) is shown experimentally to be adjusted to the emiss ion line of Nd:YAG laser.