Wafer-scale conformal metasurface optics

TL;DR

This paper introduces a scalable wafer-scale fabrication method for curved metasurface optics using thermoforming, enabling high-precision, conformal optical devices with improved performance and potential for advanced optical systems.

Contribution

The authors develop a novel thermoforming-based fabrication process for wafer-scale curved metasurfaces, including a predictive model for strain compensation to maintain optical quality.

Findings

Achieved wafer-scale production of highly curved metasurfaces with micron-level alignment.

Demonstrated diffraction-limited performance of thermoformed metasurfaces.

Created a compound eye device with expanded field of view and reduced aberrations.

Abstract

Curved and conformal optics offer significant advantages by unlocking additional geometric degrees of freedom for optical design. These capabilities enable enhanced optical performance and are essential for meeting non-optical constraints, such as those imposed by ergonomics, aerodynamics, or wearability. However, existing fabrication techniques such as direct electron or laser beam writing on curved substrates, and soft-stamp-based transfer or nanoimprint lithography suffer from limitations in scalability, yield, geometry control, and alignment accuracy. Here, we present a scalable fabrication strategy for curved and conformal metasurface optics leveraging thermoforming, an industry-standard, high-throughput manufacturing process widely used for shaping thermoplastics. Our approach uniquely enables wafer-scale production of highly curved metasurface optics, achieving sub-millimeter radii of curvature and micron-level alignment precision. To guide the design and fabrication process, we developed a thermorheological model that accurately predicts and compensates for the large strains induced during thermoforming. This allows for precise control of metasurface geometry and preservation of optical function, yielding devices with diffraction-limited performance. As a demonstration, we implemented an artificial compound eye comprising freeform micro-metalens arrays. Compared to traditional micro-optical counterparts, the device exhibits an expanded field of view, reduced aberrations, and improved uniformity, highlighting the potential of thermoformed metasurfaces for next-generation optical systems.