Multicycle AR coatings: a theoretical approach

Abstract

A theoretical approach to design multicycle AR coatings with predetermined residual reflectance, bandwidth, and cycle number is presented. The approach uses a novel step-index concept involving symmetric or asymmetric quarter-wave layer sequences to substitute refractive indices which are less than a given low refractive index. These substitutions result in a chosen step-down index profile matching the refractive index of the substrate to air. Each step of the index profile is the origin of a cycle of the synthesized AR design. Multicycle AR designs for the visible region with bandwidths of 1.6, 2.0, and 3.0 are presented as examples.