Multilevel transmission contrast in optical structures with thin films of GeTe

Abstract

Analysis of the optical properties: refractive index n(λ) and extinction coefficient k(λ), of thin films of phase-change materials obtained by photometric and ellipsometric methods allows to optimize optical characteristics reflection R, transmission T and absorption A. The interference of an electromagnetic wave in an absorbing thin film on a dielectric substrate significantly affects the values of the optical characteristics. Optimization of the optical characteristics is possible through the use of additional layers of dielectric materials, which are used to compensate for the difference in the refractive indices of the film with the substrate and air and minimize the reflection. This approach will increase the contrast of the transmission levels for the modulated optical signal in near infrared range. Calculations of the optical characteristics of thin films of germanium telluride in multi-layer structures are performed. Experimental samples of structures with antireflection layers of zinc sulfide have been prepared and their optical transmission characteristics have been investigated. The combination of multilayer structures for the implementation of contrast levels of transmission have been determined.