Measurement complex refractive index for molten optical disk materials

Abstract

We have developed a system for the measurement of the complex refractive index of both molten and solid chalcogenide materials at high temperature. The system consists of a spectroscopic ellipsometer, an infrared heating system, and prism optics. A sealed custom fabricated quartz cell was used to confine the chalcogenide sample material; the cell was evacuated to avoiding sample degradation due to oxidation or evaporation. The complex refractive index of molten and solid Sb₂Te₃ was measured over a wavelength range from 300 to 1000 nm. The imaginary part of the complex refractive index of the molten state was found to be significantly smaller than that of the solid over the observed wavelength range. Our results are consistent with the idea that a molten area created in the center of a focused laser spot can function as a small dynamic aperture in the super-resolution readout effect in optical disks.