Results in Physics (Mar 2020)
Measurement of the optical dielectric properties of thin-film materials by ultrafast time-resolved interferometry
Abstract
We report a time-resolved optic interferometry (TROI) that enables to straightway probe the optical properties of traditional and special thin-film materials by feat of a phase delayed-interference between double beams of femtosecond laser synchronously traveling through vacuum (air) and sample, respectively. As a verification of measurement accuracy created by the TROI, the group and phase velocities as well as the refractive index of noncrystal thin-film HfO2, the crystal thin-film materials YAG (isotropic cubic system), and LiNbO3 (aeolotropic rigonal system), are measured by femtosecond laser pulse with 800 nm central wavelength. The data exhibit a satisfactory consequence in which even a subtle change of measurand can be ascertained by manipulating the resolution in temporal and spacial domains via the delay-line, whether the films are isotropic or aeolotropic and any different orientations of sample. Unambiguously, the presented TROI is conspicuous to the precision measurements of environment-dependent and phase-sensitive optical parameters especially involved in specific nanoscale optical devices and structured layers or coatings.