Four-wave peak mid-infrared graphene surface plasmons absorber based on circular and orthogonal double ellipses

This paper proposes a four-wave peak narrow-band surface patterned graphene absorber based on surface plasmon resonance (SPR). The absorber is divided into three layers; the bottom layer (reflective layer) consists of Ag, the middle layer (dielectric layer) consists of silica, and the top layer (absorber material layer) of patterned graphene consists of a circle surrounding two orthogonal ellipses with a circle etched off in the middle. After analyzing and comparing the structure of different parameters of the top graphene pattern, we demonstrate the superiority of the simulation results of the used graphical parameters. This absorber top graphic structure is simple, with low machining difficulty and processing cost, and can be manufactured quantitatively. The Finite-Difference Time Domain (FDTD) simulation data in the mid-infrared waveband from 3000 nm to 3550 nm shows that this absorber structure has four perfect absorber crests. The absorption peaks at the resonance wavelengths of 3137.56 nm, 3177.06 nm, 3264.16 nm and 3394.12 nm were 98.72 %, 99.33 %, 99.97 % and 98.28 %, respectively. The average absorption of the four absorption peaks reached 99.07 %. The simulation reveals that the resonance wavelength can be controlled by the chemical potential and relaxation time of the graphene layer and by adjusting the refractive index of the silica layer. The absorber is insensitive to changes in the tilt angle and polarization mode of the incident light. At the same time, it is very sensitive to changes in the external environment refractive index. The sensitivity of the four absorption peaks was calculated to be 1004.22 nm/RIU, 1073.31 nm/RIU, 1114.01 nm/RIU and 1161.11 nm/RIU. The absorber has a variety of properties that make it highly useful in the fields of mid-infrared thermal radiation sensing, mid-infrared detectors and sensors, and environmental monitoring sensors. [Display omitted] •The absorber has four perfect narrow band absorption peaks in mid-infrared band.•The absorber achieves active tunability over a wide range.•The absorber has good refractive index sensitivity and high wavelength response speed.