Omnidirectional broadband metasurface absorber operating in visible to near-infrared regime

We present an omnidirectional broadband metasurface absorber whose dielectric-metal-dielectric layers are modulated by cylinder arrays. The simultaneous excitation of surface plasmon resonance and localized surface plasmon resonance affords an average optical absorption of 0.97 (0.9, experiment), with peak absorption up to 0.99 (0.984, experiment), for the wavelength range of 400-1100 nm, and absorption >0.93 (0.87, experiment) for incident angles up to 60°. The device, which is fabricated by continuously variable spatial frequency photolithography, outperforms previously reported absorbers in cost. Moreover, it exhibits considerably lower emissivity (weak absorption) in the mid-infrared range, which makes it promising for energy harvesting.