Inverse design enables large-scale high-performance meta-optics reshaping virtual reality

Abstract

Meta-optics has achieved major breakthroughs in the past decade; however, conventional forward design faces challenges as functionality complexity and device size scale up. Inverse design aims at optimizing meta-optics design but has been currently limited by expensive brute-force numerical solvers to small devices, which are also difficult to realize experimentally. Here, we present a general inverse-design framework for aperiodic large-scale (20k × 20k λ2) complex meta-optics in three dimensions, which alleviates computational cost for both simulation and optimization via a fast approximate solver and an adjoint method, respectively. Our framework naturally accounts for fabrication constraints via a surrogate model. In experiments, we demonstrate aberration-corrected metalenses working in the visible with high numerical aperture, poly-chromatic focusing, and large diameter up to the centimeter scale. Such large-scale meta-optics opens a new paradigm for applications, and we demonstrate its potential for future virtual-reality platforms by using a meta-eyepiece and a laser back-illuminated micro-Liquid Crystal Display.

Ultracompact multifunctional metalens visor for augmented reality displays

“…Despite the dispersion characteristics, we also successfully demonstrated red, green, and blue color imaging using the metalens-visor, while being able to see through the real world without obvious distortion or color in delity. Although the chromatic aberration has always been an inherent limitation of metasurfaces, it can be corrected through multiple methods, such as compound achromatic metalens with multilayer structure [20,34], compensation by refractive optics [55], separate engineering of phase, group-delay and group-delay-dispersion [24,56] or other techniques based on coupled resonances to tailor phase pro les at discrete [21,22,31,57] or broadband [58,59] wavelengths. In addition, the diffraction e ciencies of green and blue light are currently lower than that of red.…”

Empowering Metasurfaces with Inverse Design: Principles and Applications

“…For two to five parameters, Chebyshev interpolation is a very efficient surrogate; however, the need for training data goes exponentially with the number of degrees of freedom. Recently, Li et al demonstrated a centimeter-scale inverse-designed meta-optics (Figure (b)) using this type of surrogate . The aperiodic meta-optics contains ∼ a billion unit cells and shows wavelength- and polarization-dependent functionalities.…”

“…(b) Photography of a 1 cm diameter RGB-achromatic metalens by using inverse design. Reprinted with permission from ref . Copyright (2020) The Author(s) .…”

“…A next-generation VR platform was demonstrated by combining a meta-optics and a miniaturized fiber scanning display. In a recent work, Li et al demonstrated an inverse design framework that is well suited for a large-scale (cm-scale) metasurface optimization problem . The combination of large-aperture meta-optics and a laser back-illuminated micro-LCD opens a new path to compact and high-resolution VR imaging.…”

Diffractive Nonlocal Metasurfaces

“…We suggest in particular augmented reality as an application uniquely benefiting from this combination of features: the broadband transparency of such a metasurface (or compound metaoptic) may let the majority of external information reach the user, while the narrowband anomalous reflection may redirect artificially generated information to the user. The use of metasurfaces for augmented reality applications has received significant recent attention [138][139][140][141][142][143] owing to the light-weight, compact footprint and ability to serve as a focusing element for magnification in the imaging system. However, broadband metasurfaces are inherently limited by reciprocity: the efficiency with which artificial information is focused is the same as the efficiency with which external information is distorted or lost.…”