Birefringence of CuGaxAl1-xSe2 crystals

Abstract

Excitonic reflection spectra of CuAlSe2 crystals were studied at 10 K. The spectral dependences of refractive indices no and ne were calculated. The isotropic wavelength (the point of intersection of no and ne) in the excitonic region was determined. The spectral dependence of Δn = no − ne was studied on the long-wavelength and short-wavelength sides of the isotropic wavelength of CuGaxAl1 − xSe2 crystals. Up to 15 narrow transmission (absorption) lines were revealed in the interference spectra of thin crystals, which can be used for the development of comb filters.