Polarization-insensitive subwavelength grating reflector based on a semiconductor-insulator-metal structure.

We present a polarization-insensitive subwavelength grating reflector based on a semiconductor-insulator-metal structure. The polarization-insensitive characteristic originates from the combined effect of the TM-polarized high-reflectivity high-index-contrast subwavelength grating and the TE-polarized metallic (Au) subwavelength grating with the addition of the insulator layer. The overlapped high reflectivity (>99.5%) bandwidth between the transverse electric polarization and the transverse magnetic polarization is 89 nm. This polarization-insensitive subwavelength grating reflector can be used in the applications without a preferred polarization.