OPTICAL-PROPERTIES OF AN ISOTROPIC LAYER ON A UNIAXIAL CRYSTAL SUBSTRATE

The optical properties of a homogeneous isotropic layer on an anisotropic uniaxial crystal are characterized by four reflection amplitudes (r(ss), r(sp), r(pp), r(ps)) and four transmission amplitudes (t(so), t(se), t(po), t(pe)). We give analytic expressions for these amplitudes. Some recent experiments relating to the geophysically important phenomenon of the surface melting of ice below 0-degrees-C are discussed. The weak anisotropy of ice is amplified a hundredfold by index matching (the refractive indices of ice and water are not very different), but it is still qualitatively correct to interpret the experiments by assuming ice to be isotropic. An appendix gives the theory of what is measured in polarization modulation ellipsometry when anisotropy is present, and another appendix discusses the enhancement of anisotropy ty refractive index matching.