Spectral filter in short-wave infrareds based on a metasurface on silicon-on-insulator with polarizing bandpass.

Abstract

Spectral filters with polarimetric character in short-wave infrareds are urgently needed because of their broad applications in optic-fiber communications, polarimetric detections, and imaging. Based on our earlier progress in developing polarimetric devices in infrared wavelengths, in this work, a plasmonic-metasurface-based polarization-dependency multi-channel narrowband filter in short-wave infrareds was developed. To meet the requirement by the developing trend of polarimetric detection/spectral imaging in short-wave infrareds, a resonant cavity in the form of the Au hat/elliptical Si/SiO2 pillars/Au layer as the filters was proposed. Numerical simulations by finite-difference time-domain (FDTD) show resonant and polarized transmissions of the designed devices to infrared light in short wavelengths, and the peak positions are relevant to the structural dimensions. Optical characteristics of the filters, fabricated by electron beam lithography/dry-etch technique, agree well with the simulated behavior. To enhance the transmission efficiency to the applicable level, nanoprocessing of the filters still needs to be optimized. Nevertheless, the progress reported is promising for this new type of spectral filters based on modern metasurfaces.