UV-visible broadband wide-angle polarization-insensitive absorber based on metal groove structures with multiple depths.

A new periodic Al groove structure coated by SiO thin film is designed and numerically investigated for wide-angle and polarization-insensitive broadband absorption. A metal groove array presents optical absorption enhancement due to the cavity mode resonance, with the absorption peak capable of being shifted by controlling the depth of the metal groove. Broadband absorption can be realized by a periodic array of metal grooves with different depths combined in one single period. A two-dimensional Al structure with four different grooves in each period is designed to realize polarization-insensitive broadband absorption from 220 nm to 800 nm with average absorption efficiency over 80% within the incident angle of 40°. These wide-angle and broadband absorption structures can be applied in UV/visible-related biochemical sensors, solar cells, or photocatalysts.