Refractive index of GaP and its pressure dependence

Abstract

The refractive index n of GaP and its dispersion have been measured at pressures P from 0 to 13 GPa. The pressures were applied with a diamond anvil cell and measured with the ruby fluorescence technique. Within the P range mentioned, n was shown to decrease sublinearly with pressure. The data were fitted with a model which includes the lowest direct energy gap ${E}_{0}$, the corresponding bound exciton, and the ${E}_{1}$ gap as the main dispersion mechanisms. As fitting parameters only the strengths of the ${E}_{0}$ transition and its excitonic component were used.