Application of Polarization Modulation Technique to Acquisition of Optical Properties of Thin Films

摘要

The polarization of the incident light is set to be linear light by a polarizer. Two photoelastic modulators and two lock-in amplifiers are used to analyze the polarization of the emerging light from a sample surface. The change in polarization related to the optical properties of the sample, can be denoted by the Mueller matrix for reflection. By calculating the Mueller matrix for reflection of the sample, the optical constants, such as refractive index n, extinction coefficient k, even the dielectric constant a, electrical conductivity o and reflectivity R can be acquired. The thermal oxidized SiO_2-coating on Si (111) single crystal wafers is used for calibration. The accuracy on the refractive index is less than 3%. Optical properties of two CVD diamond films, some metal films such as Al, Au and permalloy are measured and discussed.