Multi-channel mid-infrared filter structure based on bilayer metallic grating

A planar array structure of multi-channel narrowband filter was proposed, which consisted of bilayer metallic grating and its bilateral distributed Bragg reflectors (DBRs). The central wavelength range of the designed multi-channel filter exceeded 200 nm, and the central wavelength of each channel could be adjusted by grating slit width to realize the multi-channel narrowband filter array. The results provides a new approach for designing the multi-channel mid-infrared narrowband filter.