GaN Metalens for Pixel-Level Full-Color Routing at Visible Light

TLDR

Metasurface components promise flat optics, yet their low efficiency limits practical use, and metallic mirrors improve efficiency only for reflective devices. The authors designed an out‑of‑plane focusing dielectric metalens that multiplexes blue, green, and red light into distinct spatial positions, experimentally validating a color‑routing metalens. The GaN‑based metalenses achieved transmission efficiencies of 87 %, 91.6 %, and 50.6 % for blue, green, and red, demonstrating a low‑cost, semiconductor‑compatible platform for high‑efficiency flat optics in imaging, spectroscopy, and lithography.

Abstract

Metasurface-based components are known to be one of the promising candidates for developing flat optical systems. However, their low working efficiency highly limits the use of such flat components for feasible applications. Although the introduction of the metallic mirror has been demonstrated to successfully enhance the efficiency, it is still somehow limited for imaging and sensing applications because they are only available for devices operating in a reflection fashion. Here, we demonstrate three individual GaN-based metalenses working in a transmission window with extremely high operation efficiency at visible light (87%, 91.6%, and 50.6% for blue, green, and red light, respectively). For the proof of concept, a multiplex color router with dielectric metalens, which is capable of guiding individual primary colors into different spatial positions, is experimentally verified based on the design of out-of-plane focusing metalens. Our approach with low-cost, semiconductor fabrication compatibility and high working efficiency characteristics offers a way for establishing a complete set of flat optical components for a wide range of applications such as compact imaging sensors, optical spectroscopy, and high-resolution lithography, just named a few.