Flexible, double-sided broadband optical absorber based on tapered concave nanostructure

An optical absorber with the advantages of flexibility, broadband, insensitivity to incident angle and high efficiency in double-sided incidence is studied, realized and characterized. The absorber is composed of the tapered concave nanostructure covered with thin Ni-SiNx film. Simulation results show that there exist two different mechanisms in the absorptive behavior. The absorption is measured as 94.2% and 93.9% from 400 nm to 1600 nm in the front- and back-sided incidence, respectively. The absorber is fabricated by economic process, thus it can have a variety of potential applications, such as solar–thermal energy harvesting, thermal radiation detection, etc.