Spin‐Selective Absorption and Geometric‐Phase Modulation via Chiral Metasurface in Triple Bands

Abstract

Metasurfaces with spin‐selective reflection or transmission functions for circularly‐polarized (CP) incident waves have aroused researchers' great attention. However, current spin‐selective metasurface designs have yet to mature into a practical method due to the limitations of single operating band or inefficient phase modulation. Herein, a novel chiral meta‐atom is proposed, exhibiting spin‐selective absorption/reflection functions for dual‐orthogonal CP incident waves at three different operating bands. More significantly, the Pancharatnam–Berry phase theory is introduced at all working frequencies to generate a full 2π reflection phase modulation by rotating the chiral resonator, and the three distinct absorption bands remain almost constant with the rotation. Theoretical results indicate that high absorption can separately act on left‐handed or right‐handed CP incident waves at triple bands, and meanwhile, the other incident wave with different handedness is efficiently reflected without changing the handedness. As a proof of concept, two tri‐band meta‐devices with spin‐selective anomalous reflection and spin‐selective orbital angular momentum generating functions are designed and experimentally characterized, both of which exhibit excellent spin‐dependent bi‐functional performances at three different operating bands. The research results provide a promising route to realize spin‐selective meta‐devices with multi‐band operating modes in wireless communication systems and multispectral imaging and information encryption fields.

Broadband spin-decoupled metasurface for independent wavefront manipulations of orthogonal circularly-polarized waves

“…Hence, a significant propagation phase shift is typically confined to the strong resonant frequency. (2) chiral spin-selective metasurface based on geometric phase [31][32][33]. Metasurfaces with spin-selective functions utilize the chirality effect of unit structures to filter out one circular polarization state, reflecting only the other spin state at the resonant frequency.…”

Perovskite single-pixel detector for dual-color metasurface imaging recognition in complex environment

“…In contrast, optical materials with a control of more degrees of freedom of light hold promise for larger information storage capacities [5][6][7] . A notable example is optical metasurfaces, which feature a periodic subwavelength unit cell structure, enabling independent control over several degrees of freedom of light [8][9][10][11] , including wavelength [12][13][14] , polarization 15,16 , amplitude 17,18 , momentum [19][20][21] , and phase [22][23][24] . This capability enables metasurfaces to achieve excellent optical multiplexing and makes them promising for optical image information storage with large capacities.…”