Nested Trampoline Resonators for Optomechanics

TL;DR

This paper presents the design and fabrication of nested trampoline resonators made from LPCVD Si3N4 with DBR mirrors, achieving high mechanical quality factors and optical finesse, advancing optomechanical device performance.

Contribution

The authors introduce a nested double resonator structure with high mechanical isolation and optical finesse, demonstrating significant improvements for optomechanical applications.

Findings

Achieved 80 dB mechanical isolation at the inner resonator frequency.

Fabricated devices with mechanical Q factors around 400,000 at room temperature.

Realized optical cavities with finesse up to 181,000.

Abstract

Two major challenges in the development of optomechanical devices are achieving a low mechanical and optical loss rate and vibration isolation from the environment. We address both issues by fabricating trampoline resonators made from low pressure chemical vapor deposition (LPCVD) Si$_3$N$_4$ with a distributed bragg reflector (DBR) mirror. We design a nested double resonator structure with 80 dB of mechanical isolation from the mounting surface at the inner resonator frequency, and we demonstrate up to 45 dB of isolation at lower frequencies in agreement with the design. We reliably fabricate devices with mechanical quality factors of around 400,000 at room temperature. In addition these devices were used to form optical cavities with finesse up to 181,000 $\pm$ 1,000. These promising parameters will enable experiments in the quantum regime with macroscopic mechanical resonators.