Dual-Peak Near-Perfect Absorption of Amorphous Silicon Nanocylinder Cluster Metasurface

In this paper, an amorphous silicon (a-Si) nanocylinder cluster metasurface is used to realize dual-peak near-perfect absorption in the visible spectral range. The contributions of electric dipole (ED), magnetic dipole (MD), and electric quadrupole to the scattering cross section of the nanocylinder cluster metasurface are studied via discrete dipole approximation. The transmission, reflection, and absorption spectra and electric field distribution of the a-Si nanocylinder cluster metasurface are simulated and analyzed. The Mie resonance of ED, MD, and electric quadrupole is tuned for the overlap and coherent coupling of the spectra, which further results in the local enhancement of the electric field and the dual-peak near-perfect absorption in the visible spectral range that is insensitive to the incident angle. The dual-peak near-perfect absorption of the a-Si nanocylinder cluster metasurface with low loss and angle insensitivity is expected to be applied to nanophotonic fields such as optical separation and energy collection.