Stimulated Brillouin Scattering in Multilayer Silicon Nitride Waveguides

We investigated stimulated Brillouin scattering (SBS) in two different multilayer silicon nitride waveguides. We report the first observation of SBS in multilayer silicon nitride waveguides. The gain coefficient measured is $0.16 \mathrm{m}^{-1} \mathrm{W}^{-1}$ in one of our samples, but SBS gain is absent in the other sample. We developed a simulation method, which shows how the bigger intermediate layer of 500 nm results in high gain, and the smaller layer of 100 nm results in lower gain. We can use these simulations to optimize our waveguide design. This will allow us to functionalize SBS in silicon nitride waveguides.