Impacts of tapered sidewall profile on subwavelength grating wideband reflectors

Abstract

We have demonstrated the significant impacts of grating tapered sidewall profile on the subwavelength grating wideband reflector characteristics when taking into account the practical fabrication process. Two different classes of wideband reflectors, referred to as zero-contrast gratings and high-contrast gratings, are numerically investigated in detail and the distinct differences of the impacts due to a grating tapered sidewall are observed. Our works reveal that this tapered sidewall profile plays a critical role in determining the reflection bandwidth, average reflectance, and the band edge. The results could be widely utilized in applications of a variety of nanophotonic devices and their integration, as well as facilitate the design of the fabrication process on how to control the degree of tapered sidewall profile for the integrated subwavelength grating nanophotonic devices.