Some Optical Properties of Strontium Titanate Crystal

Abstract

Clear, colorless macrocrystals of strontium titanate grown by flame fusion are isotropic, with refractive index varying from 2.37 at 0.7 micron to 2.67 at 0.4 micron, where they exhibit a sharp absorption edge corresponding to an activation energy of 3.1 electron volts. The transmittance window extends from this edge to 7 microns with an absorption coefficient (α/cm) below 20; the transmittance of a polished plate 0.25 mm thick does not fall below 40% in the region 0.4 to 7 microns.