Suspension-Free Integrated Cavity Brillouin Optomechanics on a Chip

TL;DR

This paper demonstrates a suspension-free, chip-scale cavity Brillouin optomechanical system on lithium-niobate that achieves coherent photon-phonon interactions, high stability, and multi-channel operation, advancing integrated quantum photonics.

Contribution

It introduces a suspension-free racetrack microring resonator platform for cavity Brillouin optomechanics, enabling scalable, stable, and multi-channel photon-phonon interactions on a chip.

Findings

Achieved a maximum cooperativity of 0.41.

Demonstrated a phonon Q-factor-frequency product of 10^13 Hz.

Enabled multi-channel operations across 300 MHz phonon and 40 nm optical wavelength ranges.

Abstract

Cavity optomechanical systems enable coherent photon-phonon interactions essential for quantum technologies, yet high-performance devices have been limited to suspended structures. Here, we overcome this limitation by demonstrating cavity Brillouin optomechanics in a suspension-free racetrack microring resonator on a lithium-niobate-on-sapphire chip, a platform that merits high stability and scalability. We demonstrate coherent coupling between telecom-band optical modes and a 9.6-GHz phonon mode, achieving a maximum cooperativity of $0.41$ and a phonon quality-factor-frequency product of $10^{13}\,\mathrm{Hz}$. The momentum-matching condition inherent to traveling-wave Brillouin interactions establishes a one-to-one mapping between optical wavelength and phonon frequency, enabling multi-channel parallel operations across nearly $300\,\mathrm{MHz}$ in phonon frequency and $40\,\mathrm{nm}$ in optical wavelength. Our suspension-free architecture provides a coherent photon-phonon interface compatible with wafer-scale integration, opening pathways toward hybrid quantum circuits that unite photonic, phononic, and superconducting components on a single chip.