Photonic Origami of Silica on a Silicon Chip with Microresonators and Concave Mirrors

TL;DR

This paper introduces a laser-induced, surface-tension-driven method to fold ultrasmooth silica on silicon chips into complex 3D photonic structures with high precision, enabling advanced integrated optical devices.

Contribution

The authors develop a novel technique for folding ultrasmooth silica into 3D structures on silicon chips with nanometer accuracy, surpassing previous fabrication limitations.

Findings

Achieved 20 nm alignment accuracy in folding

Created 3D structures with integrated microresonators and concave micromirrors

Produced structures with quality factors exceeding 8 million

Abstract

3D printing of high-quality silica photonic structures is particularly challenging, as surface roughness at the nanoscale can severely degrade optical performance through scattering losses. Here, we develop a technique to fold ultrasmooth silica on silicon chips into such desired 3D structures. A laser-induced, surface-tension-driven method achieves folding with 20 nm alignment accuracy, enabling origami-like polylines and helices with integrated 0.5 nm-smooth photonic devices. The technique allows for the fabrication of record length-to-thickness ratio structures, incorporating concave micromirrors with numerical aperture of 0.41, and microresonators with quality factors exceeding ${8 \times 10^6}$. This on-chip silica origami approach offers a pathway to transform planar electro-opto-mechanical circuits into high-quality 3D configurations.