Low-reflection region within the stop band of a finite or absorbing periodic multilayer

Abstract

Nonabsorbing periodic multilayers reflect both the s(TE) and p(TM) polarizations strongly within the respective stop bands. We find that finite or weakly absorbing layers, for which the reflection is usually strong within the stop bands, can have zero or very weak reflection of the p polarization near the middle of the stop band, close to glancing incidence. Approximate expressions are derived for the location (in angle of incidence and frequency) of the reflection minimum and compared with calculated reflectances for specific multilayers.