Dual-Period Guided-Mode Resonance Filters For Swir Multi-Spectral Image Sensors

Typical guided-mode resonance (GMR) transmission filter design, which is based on a single ridge per period, necessitates multiple etching/fabrication steps for implementing an array of filters (having different transmission bands) on the same substrate. To address this problem, we demonstrate dual-period narrow bandpass GMR filters that offer more degrees of freedom, two periods and two fill-factors, for tuning the filter characteristics and achieving wider stop bands without changing the grating height. A set of six transmission filters with well-separated passbands in the short-wave infrared region was designed using COMSOLMultiphysics simulations and produced on the same silicon-on-quartz wafer in a single fabrication run. The 90 mu m x 90 mu m size filters exhibited passbands as narrow as 15 nm with peak-wavelength tunability over 200 nm, flat stop bands as wide as similar to 400 nm, and peak transmittance reaching 87%. The experimental transmission spectra were in good agreement with the corresponding simulations. These findings pave the way for the realization of pixel size filter arrays for multispectral image sensors. (C) 2021 Optical Society of America