Silica aerogel cavity enhancement of spectral reflection from distributed Bragg reflectors with patterned surfaces

Abstract

Distributed Bragg reflectors (DBRs) can experience thermomechanical issues under an intense incident beam. A remedy for this issue is to pattern the DBR structure to facilitate thermal expansion in the structure. However, finite-size patterns reduce the design’s electromagnetic performance, including the reflectivity amplitude and the operational bandwidth. Here, we introduce a silica aerogel cavity medium between the DBR layer and the substrate to increase the reflection by stimulating the cavity modes. By altering the cavity layer’s thickness and the pattern width, the interference of reflected lights can be controlled and enhance the reflectivity at desired wavelengths. The results show a significant enhancement in the reflection by introducing the cavity in the design. For a comprehensive investigation of the mechanisms, the interaction of the DBR layers with the substrate, the effect of patterns, and the propagation of electric fields, especially in the cavity layer, are examined.