# Electromechanical Brillouin scattering in integrated optomechanical waveguides

## TL;DR

This paper demonstrates electromechanically excited Brillouin scattering in integrated AlN waveguides, enabling tunable single-sideband modulation and offering a promising interface between microwave and optical photons for advanced photonic applications.

## Contribution

It introduces a novel approach to excite Brillouin scattering electromechanically in integrated photonics using piezoelectric AlN, with tunable phase-matching for enhanced control.

## Key findings

- Achieved 16 GHz acoustic phonon excitation with nanofabricated transducers.
- Demonstrated tunable phase-matching by varying optical wavelength and acoustic frequency.
- Enabled efficient microwave-optical photon interfacing in integrated platforms.

## Abstract

In the well-known stimulated Brillouin scattering (SBS) process, spontaneous acoustic phonons in materials are stimulated by laser light and scatter the latter into a Stokes sideband. SBS becomes more pronounced in optical fibers and has been harnessed to amplify optical signals and even achieve lasing. Exploitation of SBS has recently surged on integrated photonics platforms as simultaneous confinement of photons and phonons in waveguides leads to drastically enhanced interaction. Instead of being optically stimulated, coherent phonons can also be electromechanically excited with very high efficiency as has been exploited in radiofrequency acoustic filters. Here, we demonstrate electromechanically excited Brillouin scattering in integrated optomechanical waveguides made of piezoelectric material aluminum nitride (AlN). Acoustic phonons of 16 GHz in frequency are excited with nanofabricated electromechanical transducers to scatter counter-propagating photons in the waveguide into a single anti-Stokes sideband. We show that phase-matching conditions of Brillouin scattering can be tuned by varying both the optical wavelength and the acoustic frequency to realize tunable single-sideband modulation. Combining Brillouin scattering photonics with nanoelectromechanical systems, our approach provides an efficient interface between microwave and optical photons that will be important for microwave photonics and potentially quantum transduction.

---
Source: https://tomesphere.com/paper/1905.03810