Angle-multiplexed metasurfaces: encoding independent wavefronts in a single metasurface under different illumination angles

TL;DR

This paper introduces angle-multiplexed metasurfaces that can independently control optical wavefronts under different illumination angles, enabling flat optical devices with multiple functionalities based on incident direction.

Contribution

The authors develop reflective high-contrast dielectric U-shaped meta-atoms that independently respond to different angles, overcoming the inherent angular correlation in traditional diffractive optical elements.

Findings

Demonstration of independent wavefront control at multiple angles

Design of metasurfaces with angle-specific optical transformations

Potential for multi-functional flat optical devices

Abstract

The angular response of thin diffractive optical elements is highly correlated. For example, the angles of incidence and diffraction of a grating are locked through the grating momentum determined by the grating period. Other diffractive devices, including conventional metasurfaces, have a similar angular behavior due to the fixed locations of the Fresnel zone boundaries and the weak angular sensitivity of the meta-atoms. To alter this fundamental property, we introduce angle-multiplexed metasurfaces, composed of reflective high-contrast dielectric U-shaped meta-atoms, whose response under illumination from different angles can be controlled independently. This enables flat optical devices that impose different and independent optical transformations when illuminated from different directions, a capability not previously available in diffractive optics.