Narrow line-width reflection infrared filter using subwavelength metal-dielectric grating structure (Conference Presentation)

It has been well-known that subwavelength metal slits grating structures function as extraordinary optical transmission filters due to excitation of surface plasmon-polaritons. In this work, we show that complex metal-dielectric subwavelength grating structures can also be designed to function as reflection-type optical filters with narrow spectral line-width in the infrared regime. Unlike extraordinary transmission filters, the new reflection optical filters with sharp spectral profiles can be designed within the entire infrared range by adjusting the height and period of the subwavelength grating structure. Detailed analysis has shown that the contrast of refractive indices of two dielectric materials embedded in the metal-dielectric structure is critical for giving sharp reflection spectral profiles.