Observation of a Brillouin dynamic grating in silicon nitride waveguides

Brillouin enhanced four wave mixing in the form of a Brillouin dynamic grating (BDG) enables a uniquely tunable filter whose properties can be tuned by purely optical means. This makes the BDG a valuable tool in microwave photonics (MWP). BDGs have been studied extensively in fibers, but the only observation in an integrated platform required exotic materials. Unlocking BDG in a standard and mature platform will enable its integration into large-scale circuits. Here, we demonstrate the first observation of a BDG in a silicon nitride (Si₃N₄) waveguide. We also present a new and optimized design, which will enhance the BDG response of the waveguide, unlocking the path to large-scale integration into MWP circuits.