Silicon-on-sapphire metasurfaces generate arrays of dark and bright traps for neutral atoms

TL;DR

This paper presents the design and fabrication of crystalline silicon-on-sapphire metasurfaces that generate complex optical trap arrays for neutral atoms, offering scalable, CMOS-compatible solutions with improved stability over traditional active components.

Contribution

It introduces a novel design method for 3D optical bottle beams using modified Gerchberg-Saxton algorithm and demonstrates scalable, CMOS-compatible metasurfaces for atom trapping.

Findings

Successfully fabricated silicon-on-sapphire metasurfaces for trap arrays

Generated arrays of bright, dark, and interleaved traps

Achieved scalable and stable trap generation with CMOS-compatible processes

Abstract

We demonstrated crystalline silicon-on-sapphire (c-SOS) metasurfaces that convert a Gaussian beam into arrays of complex optical traps, including arrays of optical bottle beams that trap atoms in dark regions interleaved with bright tweezer arrays. The high refractive index and indirect band gap of crystalline silicon makes it possible to design high-resolution near-infrared ($\lambda>700$ nm) metasurfaces that can be manufactured at scale using CMOS-compatible processes. Compared with active components like spatial light modulators (SLMs) that have become widely used to generate trap arrays, metasurfaces provide an indefinitely scalable number of pixels, enabling large arrays of complex traps in a very small form factor, as well as reduced dynamic noise. To design metasurfaces that can generate three-dimensional bottle beams to serve as dark traps, we modified the Gerchberg-Saxton algorithm to enforce complex-amplitude profiles at the focal plane of the metasurface and to optimize the uniformity of the traps across the array. We fabricated and measured c-SOS metasurfaces that convert a Gaussian laser beam into arrays of bright traps, dark traps, and interleaved bright/dark traps.