Narrowband Perfect Absorber Based on Metal-Dielectric-Metal Stacks for
Mid-IR Optical Gas Sensing
Abstract
Mid-infrared absorbers based on metamaterials are investigated
intensively for gas detection applications, owing to its ability to
achieve excellent light absorption by manipulating electromagnetic
waves. Herein, we present a metamaterial absorber for the ultra-compact
optical gas sensor. This absorber has 99.9% absorption at 6.2 μm. The
full width at half-maximum of the peak was 720 nm. As a sensor, the
absorber had an average linear spectral sensitivity of 876 nm/RIU and a
detection limit of 1.141×10-5 RIU, when the RI of the gas medium varied
between 1 and 1.05. The designed absorber would have great potential
application in guiding the design of optical gas sensors.