Surface-plasmon-polariton spectral absorption device based on periodic chirp structure

Abstract

The invention discloses a surface-plasmon-polariton spectral absorption device based on a periodic chirp structure. The surface-plasmon-polariton spectral absorption device comprises a substrate, a first metal layer and a plurality of gratings, wherein the first metal layer is positioned on the substrate; the plurality of gratings are positioned on the first metal layer; each grating comprises an insulator body positioned on the first metal layer and a second metal layer positioned on the insulator body; and the gratings are in linear chrip at least along the X direction or Z direction or along the two directions simultaneously. The surface-plasmon-polariton spectral absorption device disclosed by the invention has the advantages that since the period of the gratings adopts the linear chrip, the resonant wavelength is in linear distribution and covers larger spectral range, and the bandwidth of the whole forbidden band is realized and widened by properly adjusting a chrip coefficient of the gratings and a resonant cavity formed by an upper metal layer / insulator layer / lower metal layer, so that the possibility for realizing a low and flat reflecting forbidden belt is realized; and under the limiting condition of phase matching and sub-wavelength size, nearly-perfect absorption of the bandwidth can be realized by proper design.

Description

Technical field [0001] The invention relates to the technical field of surface plasmon resonant cavities, in particular to a surface plasmon resonant cavity spectral absorption device based on a periodic chirp structure. Background technique [0002] Metal is generally considered to be a highly efficient reflector and is sometimes used as a mirror. However, when the metal surface is etched into micro-nano structures according to the required operating wavelength, the reflected light on the metal surface can be greatly reduced. The micro-nano structure may become a highly efficient absorber in a large electromagnetic wave range, from visible light, infrared to microwave. In the past few years, this has aroused great interest and triggered a lot of theoretical and experimental research. In 2008, Landry et al. proposed and confirmed a metamaterial structure that almost completely absorbs. It is composed of two metamaterial resonant cavities, which are respectively coupled with el...

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Problems solved by technology

However, this structure only absorbs 70% of the incident light in the 2.5 μm band at 8.5 μm. This is because of the mutual restriction between the band and the absorption rate, which causes large fluctuations in the working wavelength range.

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