Metal-insulator-metal plasmonic grating filter with suppressed Rayleigh anomaly

Abstract

Plasmonic grating filters can be fabricated in single lithography process and reduce the cost of colour filters used in hyperspectral cameras. Due to the presence of Rayleigh Anomaly (RA) peak, however, it has not been possible to design filter array spanning wide-spectral-range without sacrificing spectral purity. In this paper, a plasmonic grating filter design using Metal-Insulator-Metal (MIM) with suppressed RA peak is presented. Proposed filter allows extending spectral range without sacrificing spectral purity. Using proposed MIM structure, surface plasmon polariton (SPP) mode supported on air side of bottom grating structure is cancelled by second set of SPP mode on top grating structure. This allows designing filter array with improved spectral range and achieves better than 2× improvement in suppression of the Rayleigh Anomaly peak.