Selective Diffraction with Complex Amplitude Modulation by Dielectric Metasurfaces

TL;DR

This paper introduces a novel dielectric metasurface technique that uses complex amplitude modulation to selectively diffract light into desired orders, enabling advanced optical control for various applications.

Contribution

It presents a new method for generating selective diffraction orders using complex amplitude modulation with dielectric metasurfaces, verified through experiments and theoretical comparisons.

Findings

Selective diffraction orders can be achieved with high efficiency.

The diffraction angles match standard grating theory.

The method enables precise control of light for optical applications.

Abstract

Metasurfaces have attracted extensive interests due to their ability to locally manipulate optical parameters of light and easy integration to complex optical systems. Particularly, metasurfaces can provide a novel platform for splitting and diffracting light into several beams with desired profile, which is in contrast to traditional gratings. Here, we propose and experimentally demonstrate a novel method for generating independently selective diffraction orders. Our method is based on complex amplitude modulation with ultrathin dielectric metasurfaces. By tailoring the geometric parameters of silicon nanofin structures, we can spatially control the geometric and dynamic phase as well as the amplitude simultaneously. We compare the results with a metasurface that uses a phase-only modulation, to verify such selective diffraction can be solely efficiently achieved with complex amplitude modulation. Besides, the diffraction angles of each order have been measured, which are consistent with standard grating theory. Our developed method for achieving selective diffraction with metasurfaces has potential applications in beam shaping, parallel laser fabrication, and nanoscale optical detection.