Spatial and frequency-selective optical field coupling absorption in an ultra-thin random metasurface

Simplified thin-film structures with the capability of spatial and frequency-selective optical field coupling and absorption are desirable for nanophotonics. Herein, we demonstrate the configuration of a 200-nm-thick random metasurface formed by refractory metal nanoresonators, showing near -unity absorption (absorptivity > 90%) covering the visible and near-infrared range (0.380-1.167 mu m). Importantly, the resonant optical field is observed to be concentrated in differ-ent spatial areas according to different frequencies, paving a feasible way to artificially manipulate spatial coupling and optical absorption via the spectral frequency. The meth-ods and conclusions derived in this work are applicable throughout a wide energy range and hold applications for frequency-selective nanoscale optical field manipulation. (c) 2023 Optica Publishing Group

Automated summary

A 200-nm-thick random metasurface composed of refractory metal nanoresonators is demonstrated to achieve spatial and frequency-selective optical field coupling and absorption. The resonant optical field is found to be concentrated in different spatial areas depending on the frequency, enabling artificial manipulation of spatial coupling and optical absorption through spectral frequency. These methods have wide applicability and potential in frequency-selective nanoscale optical field manipulation.