Abstract
With the exhaustion of world energy, new energy has become the most important content of each country’s development strategy. How to efficiently use solar energy has become a research hotspot in current scientific research. Based on surface plasmon resonance and Fabry-Perot (FP) cavity, this paper proposes a design method of asymmetric silicon grating absorber, and uses finite difference time domain (FDTD) method for simulation calculation. By adjusting the geometric parameters, the asymmetric silicon grating absorber realizes two narrow-band absorption peaks with absorption greater than 99% in the optical wavelength range of 3,000–5,000 nm, and the absorption peak wavelengths are λ1 = 3,780 nm and λ2 = 4,135 nm, respectively. When the electromagnetic wave is incident on the surface of the metamaterial, it will excite the plasmon resonance of the metal to form a surface plasmon (SP) wave. When the SP wave propagates along the x axis, the silicon grating can reflect the SP wave back and forth. When the frequency of the SP wave and the incident light are equal, it will cause horizontal FP coupling resonance, resulting in different resonance wavelengths. This paper also discusses the influence of geometric parameters, incident angle and polarization angle on the performance of silicon grating absorbers. Finally, the sensing performance of the structure as a refractive index sensor is studied. The absorber can be used for various spectral applications such as photon detection, optical filtering and spectral sensing.
Highlights
Surface plasmon resonance (SPR) is a non-radiative electromagnetic mode formed by the coupling of incident photons and free electrons on the metal surface (Cao et al, 2014)
The three silicon grating structures in a unit period make the grating as a whole asymmetrical structure. h1 represents the height of the silicon grating, h2 represents the height of the gold thin layer, w represents the width of the silicon grating, and d1 and d2 represent the center spacing of adjacent silicon gratings
We have observed that the electric field is distributed at the top corners of the slits with small silicon grating spacing, and the magnetic field is mainly distributed between the slits with small silicon grating spacing
Summary
Surface plasmon resonance (SPR) is a non-radiative electromagnetic mode formed by the coupling of incident photons and free electrons on the metal surface (Cao et al, 2014). It is an excited state that locally propagates on the medium and metal surface. Its propagation characteristics are related to the incident light source, the metal medium material and the surrounding refractive index (Jiang et al, 2021a). SPR provides a foundation for micro-nano applications due to its unique advantages, including biosensing, light field enhancement, solar cells, photocatalysis, Raman enhanced detection, and photodetectors (Liu et al, 2017; Xiao et al, 2017; Li et al, 2018; Chen et al, 2019; Li et al, 2020a; Zhao et al, 2021).
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