Hypermultiplexed off-chip hologram by on-chip integrated metasurface

TL;DR

This paper introduces a comprehensive inverse design framework for hypermultiplexed on-chip metasurfaces capable of generating multiple holograms across different wavelengths, directions, and planes, advancing multifunctional photonic chip technology.

Contribution

The paper presents a novel, physically-based inverse design method enabling hypermultiplexed metasurfaces with independent control over multiple parameters, including wavelength, direction, and target plane.

Findings

Demonstrated 9 independent holographic channels via wavelength and distance multiplexing.

Produced 36 distinct holograms by incorporating excitation direction into design.

Validated robustness of holograms against fabrication discrepancies through electromagnetic simulations.

Abstract

The waveguide-integrated metasurface introduces a novel photonic chip capable of converting guided modes into free-space light. This enables functions such as off-chip beam focusing, steering, and imaging. The challenge lies in achieving hypermultiplexing across diverse parameters, including guided-wave mode type, direction, polarization, and notably, multiple wavelengths. Here, we introduce a comprehensive end-to-end inverse design framework, rooted in a physical model, for the multifunctional design of on-chip metasurfaces. This framework allows for metasurface optimization through a target-field-driven iteration process. We demonstrate a hypermultiplexed on-chip metasurface capable of generating red-green-blue holograms at multiple target planes, with both independent and cooperative control over guided-wave direction. Significantly, the proposed method streamlines the design process utilizing only the positions of meta-atoms as the design variable. We demonstrate 9 independent holographic channels through a combination of wavelength and distance multiplexing. Moreover, by incorporating the excitation direction into the design, the metasurface produces a total of 36 distinct holograms. The robustness of these results against fabrication discrepancies is validated through 3D full-wave electromagnetic simulations, aligning well with advanced manufacturing techniques. Our research presents a universal design framework for the development of multifunctional on-chip metasurfaces, opening up new avenues for a wide range of applications.