Broadband Wide-Angle Incident Light Absorption by Metallic Loop Metasurfaces Based on Electro-Optic Substrate

A metasurface absorber based on an electro-optic (EO) substrate is numerically investigated. Flat resonant peaks are achieved in both visible and infrared regions. The spectral widths are 1012 and 556 nm, respectively, at 70% and 90% of absorption level in the waveband of 500-2000 nm. The actual absorption efficiency is calculated as 71.56%, being about that of high-efficiency multilayer absorbers. The design is characterized for its thin-metallic substrate and a spectral width of 229 nm at 98% absorption level at a single resonant mode is observed. The EO substrate is used to tune the wavelengths to the desired region of absorption by varying the applied voltage in order to reduce the use of scaling and fabrication complexities. The broad resonances can be used for power harvesting and solar thermals. Moreover, the EO-based tunability can find applications in infrared detection and optical filtering.