Optical and electro-optical properties of Tl_1-xCu_xGaSe₂ (0 ≤ X ≤ 0.02) crystals

Abstract

The anisotropy of the refractive index and the electro-optical effect in Tl1-xCuxGaSe2(0≤X≤0/02) crystals were studied. Refractive indices were shown to rise as they approach their own absorption band. The electro-optical effect in TlGaSe2 crystals was studied. It was shown that the EO effect in the case where the light and external electric field are directed along the “C” axis within the studied electric fields (up to 5 kV / cm) is quadratic. The quadratic EO effect for TlGaSe2 equals 1.3 · 10−9 CGS units. It was found that when the electric field is directed perpendicular to the “C” axis and the light is directed along the “C” axis the EO effect is linear. The results of the EO measurements are consistent with the fact that the TlGaSe2 compounds crystallize in a monoclinic lattice, with the space group Cc, but at the same time the TlGaSe2 crystals have higher symmetry than Cc.