Design and fabrication of high-performance guided-mode resonance infrared filters

Abstract

This study reports design, fabrication, and characterization of high-performance guided-mode resonance (GMR) infrared filters based on germanium (Ge) operating in the 7 to 15 µm spectral region. The GMR filters exhibit deep transmittance nulls and high sideband efficiency functioning as band-stop filters. There is reasonable agreement between experimental and theoretical spectral results. By modifying design parameters and incorporating an anti-reflection (AR) layer on the substrate backside, the functionality of the filter is significantly enhanced. The measured low transmittance value of the fabricated filters is found to be as low as 0.021% corresponding to an optical density of OD = 3.68. The one-dimensional (1D) GMR filters produced exhibit agile wavelength tunability when the angle of incidence is varied. The results highlight the potential of GMR technology operating at long infrared wavelengths with creating high performance filters with tunable spectral characteristics. Anticipated application domains include the fields of sensing, imaging, and spectroscopy.