Polygonal silica toroidal microcavity for controlled optical coupling

TL;DR

This paper presents the fabrication of polygonal silica toroidal microcavities that enable stable and controllable optical coupling with tapered fibers, combining advanced fabrication techniques and numerical simulations to optimize quality factors.

Contribution

The study introduces a novel fabrication method for polygonal silica microcavities that maintain high and low coupling efficiencies even with direct contact, enhancing practical applications.

Findings

Achieved an optical quality factor of 8.8×10^6 in octagonal microcavities.

Demonstrated stable mechanical coupling with evanescent couplers.

Fabrication process combines isotropic etching, anisotropic etching, and laser reflow.

Abstract

We fabricated polygonal silica toroidal microcavities to achieve stable mechanical coupling with an evanescent coupler such as a tapered fiber. The polygonal cavity was fabricated by using a combination of isotropic etching, anisotropic etching and laser reflow. It offers both high and low coupling efficiencies with the cavity mode even when the coupler is in contact with the cavity, which offers the possibility of taking the device outside the laboratory. A numerical simulation showed that an octagonal silica toroidal microcavity had an optical quality factor of 8.8\times10^6.