Reconfigurable all-dielectric metalens with diffraction-limited performance

Active metasurfaces, whose optical properties can be modulated post-fabrication, have emerged as an intensively explored field in recent years. The efforts to date, however, still face major performance limitations in tuning range, optical quality, and efficiency, especially for non-mechanical actuation mechanisms. In this paper, we introduce an active metasurface platform combining phase tuning in the full 2 range and diffraction-limited performance using an all-dielectric, low-loss architecture based on optical phase change materials (O-PCMs). We present a generic design principle enabling binary switching of metasurfaces between arbitrary phase profiles and propose a new figure-of-merit (FOM) tailored for reconfigurable meta-optics. We implement the approach to realize a high-performance varifocal metalens operating at 5.2 mu m wavelength. The reconfigurable metalens features a record large switching contrast ratio of 29.5dB. We further validate aberration-free and multi-depth imaging using the metalens, which represents a key experimental demonstration of a non-mechanical tunable metalens with diffraction-limited performance.

Automated summary

This study introduces an active metasurface platform with all-dielectric, low-loss architecture for phase tuning in the full 2 range and diffraction-limited performance. A new design principle enables binary switching between arbitrary phase profiles for metasurfaces, along with a figure-of-merit tailored for reconfigurable meta-optics. The high-performance varifocal metalens with a record large switching contrast ratio and aberration-free, multi-depth imaging represents a key experimental demonstration of non-mechanical tunable metalens with diffraction-limited performance.