November 30, 2025Open Access

Intramodal stimulated Brillouin scattering in suspended AlN waveguides

Key Points

A Brillouin gain coefficient of 150.37 m −1 W −1 was achieved, indicating high potential for optical systems.
The linewidth was narrowed to 9.87 MHz, showing enhanced performance for optical applications.
Observational analysis of suspended AlN waveguides provides insights into Brillouin interactions and gain.
This approach may enable future development of integrated photonic devices in optical communication.

Abstract

Abstract Aluminum nitride (AlN), a wide-bandgap III–V material, offers excellent transparency in the optical communication band and a favorable refractive index for strong optical confinement, making it a promising platform in stimulated Brillouin scattering (SBS). Here, we observe, for the first time, optically excited SBS in suspended AlN-on-silicon waveguides. A Brillouin gain coefficient of 91.8 m −1 W −1 is achieved at an acoustic frequency of 2.32 GHz, with a linewidth of 10.1 MHz. The Brillouin nonlinear response can be tailored by varying the waveguide dimensions. Furthermore, the Bragg grating–based Fabry–Pérot (FP) resonator enhances the gain coefficient to 150.37 m −1 W −1 and results in a narrowed linewidth of 9.87 MHz. These results not only validate the feasibility of strong intrinsic Brillouin interaction in suspended AlN waveguides but also pave the new way for CMOS-compatible on-chip Brillouin amplifiers, lasers, and isolators.

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