Monocrystalline AlGaAs heterostructures for high-reflectivity high-Q micromechanical resonators in the MHz regime

TL;DR

This paper demonstrates high-Q, high-reflectivity micromechanical resonators using monocrystalline AlGaAs heterostructures, achieving significant improvements in quality factor and reflectivity suitable for quantum optical applications.

Contribution

The study introduces a novel monocrystalline AlGaAs heterostructure for high-performance micromechanical resonators with exceptional optical and mechanical properties.

Findings

Optical reflectivity exceeds 99.98% at 4 K

Mechanical quality factors reach up to 20,000

Low mechanical loss due to monocrystalline heterostructure

Abstract

We present high-performance megahertz micromechanical oscillators based on freestanding epitaxial AlGaAs distributed Bragg reflectors. Compared with dielectric reflectors, the low mechanical loss of the monocrystalline heterostructure gives rise to significant improvements in the achievable mechanical quality factor Q while simultaneously exhibiting near unity reflectivity. Experimental characterization yields an optical reflectivity exceeding 99.98% and mechanical quality factors up to 20 000 at 4 K. This materials system is not only an interesting candidate for optical coatings with ultralow thermal noise, but also provides a promising path toward quantum optical control of massive micromechanical mirrors.