Phase‐Modulation Metasurface‐Based Visible Broadband Absorbers with Polarization Sensitivity or Independence

Abstract Metasurface‐based broadband absorbers have attracted widespread attention due to the advantages of ultra‐thin, lightweight, flexible design. Currently, the main design principle depends on the amplitude modulation for the incident beam, which requires high‐loss material and multiplex resonances, with fabrication duplication and severe crosstalk. Herein, two kinds of visible broadband metasurface absorbers are proposed based on the phase‐modulation principle. The first is composed of a staggered Al trapezoidal array on the SiO 2 /Al substrate, where adjacent units have a phase difference of π for the y‐polarized beam to generate the destructive interference, leading to a high average measured absorptivity of 73.37% for the whole visible band. On the contrary, this absorber reflects the x‐polarized beam with a reflectivity of 51.65%. To achieve polarization‐independent absorption, a 3×3 supercell metasurface is proposed, consisting of two groups of quasi‐trapezoidal interlaced arrangements in the x‐ and y‐directions separately. The measured spectra exhibit perfect polarization independence and excellent absorption (84.13%). Besides, both have angle robustness within 60° and refractive index robustness within 1.49. In theory, the influence of diffraction on the absorption effect is emphasized systematically. This research proposes a novel strategy to achieve broadband absorption, which can serve as a platform for polarizers, solar batteries, etc.