Narrowband infrared transmission filters via asymmetric subwavelength dielectric gratings

摘要

Narrow-band transmission filters composed of asymmetric high contrast dielectric gratings are simulated in the long-wavelength infrared region (8-12μm). The subwavelength gratings are designed to provide a high-reflectivity background, while the asymmetric geometry provides narrowband transmission that is accessible at normal incidence. Finite element modeling of these structures demonstrate that narrowband response may be tuned across the long-wavelength infrared spectral region by varying grating geometry. Among the asymmetric geometries, a two-step grating structure appears to be a promising candidate to enable normal incidence filtering with reasonable fabrication procedures. Progress on experimental methods of fabricating the asymmetric geometries will be presented at the conference.