INVESTIGATION OF OPTICAL AND ELECTRICAL PROPERTIES OF NOBLE METAL AND SUPERCONDUCTING THIN FILMS AND DESIGN AND FABRICATION OF METAMATERIAL SOLAR ABSORBERS

Abstract

An extensive study of light-matter interactions leading to the generation of photon drag voltage under surface plasmon resonance conditions in noble metal thin films was undertaken by performing a series of experimental measurements and numerical simulations. The drag voltage originates from a force that arises because of the transfer of momentum from incident light to electrons. This transfer of photon momentum leads to an electric current, which in turn results in the generation of drag voltage. The effect is particularly enhanced under surface plasmon resonance conditions and thereby reinforces the interaction between light and collective oscillations of the surface charges. Drag voltages with a nonlinear dependence on laser intensity was observed. In disagreement with previous results, a reversal in the sign of the voltage was not observed when the direction of the incident laser momentum is reversed. In addition, a guide for the design and fabrication of metamaterial microstructures consisting of TiN, SiO2 and HfO2, is presented as an absorber of visible light and heat generator. In case of the normal incidence, microstructures have exceptionally high absorption efficiency ( > 96%), for wavelength range 400 nm to 700 nm. Additionally, though these microstructures were optimized for visible light spectrum, also shows absorption of > 92% intigrated over wavelength spectrum from 400 nm to 1200 nm. Also, the heat generation effects were investigated experimentally for these microsturctures using white light at normal incidence of the light. Furthermore, we investigated the optical properties of high-Tc YBCO thin film at various temperatures to study the possible surface plasmon resonance impact at the transition temperature of the YBCO using 633nm wavelength of light. Optical constants as a function of the temperature for the YBCO thin film were obtained at normal incidence of the light.