Demonstration of Stimulated Brillouin Scattering in a Silicon Suspended Microring With Photonic-Phononic Waveguide

We design and fabricate the suspended silicon microring with racetrack and spiral structure to exploit the resonantly enhanced stimulated Brillouin scattering (SBS). The designed photonic-phononic waveguide can provide the independent control on the optical and acoustic modes by introducing the silicon ridge waveguide into the phononic crystal slab as a line defect. We demonstrate efficient forward SBS in the two kinds of microrings and extract the characteristic Brillouin parameters through the heterodyne four-wave mixing measurement. The stronger inhomogeneous broadening effect in the spiral microring due to the structural variations is also observed. In addition, our microrings show the single mode transmission spectrum and high quality factor, which is beneficial to the enhanced intramodal forward SBS. This design can readily extend to other silicon-based platforms and paves the way toward on-chip photonic-phononic signal processing and Brillouin amplifier technologies.