A high-reflectivity high-Q micromechanical Bragg-mirror

TL;DR

This paper presents the development of a micromechanical Bragg mirror with high reflectivity and mechanical quality, demonstrating its potential for integrated high-finesse optical cavities.

Contribution

It introduces a hybrid fabrication method for a high-reflectivity, high-Q micromirror suitable for on-chip optical applications.

Findings

Reflectivity of 99.6% achieved

Mechanical Q factor of approximately 10^4

Finesse of 500 in a Fabry Perot cavity

Abstract

We report on the fabrication and characterization of a micromechanical oscillator consisting only of a free-standing dielectric Bragg mirror with high optical reflectivity and high mechanical quality. The fabrication technique is a hybrid approach involving laser ablation and dry etching. The mirror has a reflectivity of 99.6%, a mass of 400ng, and a mechanical quality factor Q of approximately 10^4. Using this micromirror in a Fabry Perot cavity, a finesse of 500 has been achieved. This is an important step towards designing tunable high-Q high-finesse cavities on chip.