Design of metal-dielectric interference coatings

Abstract

Subject of study. Multilayer structures comprising a thin metal layer facilitate the creation of new optical schemes for spectroscopy (selectors for laser cavities, multibeam reflection interferometers, and interference filters with thin absorbing layers). Method. Methods for the calculation of complex optical coatings are constantly improved. The novelty of this work is the design of a stacked structure with a thin metal layer when a conductive surface model is used to mathematically describe the properties of this layer. Results. This work presents numerical modeling of several multilayer metal-dielectric structures. A graphical method for designing an asymmetric front mirror of a reflection interferometer that uses circular charts of a complex reflection coefficient ensures visual clarity when searching for an optimal solution. The proposed multilayer structure with thin metal films placed at the layer boundaries ensures effective suppression of the reflected light with wavelengths different from the selected one. A narrow extrema (maxima and minima) transformation in the spectral or angular dependences of the reflection coefficient is shown to occur in the case of the oblique incidence of s-polarized light on the multibeam reflection interferometer and the variation of the “gap” thickness. It is established that, if a thin metal film is added to the front mirror, narrow bright fringes of reflected light can be obtained in a scheme with a Fabry-Perot interferometer in addition to the fringes in transmitted light. Practical significance. The obtained results can be applied to spectroscopy.