Optimization of Suspended Phononic Crystal Brillouin Waveguides Using Genetic Algorithm

Stimulated Brillouin scattering (SBS) is explored in integrated optoelectronic systems to demonstrate microwave photonic filters, microwave sources, non-reciprocal devices, narrow-linewidth lasers, etc. Suspended structures and phononic crystals are applied to boost the SBS gain. However, the Brillouin gain coefficient is related to multiple factors such as electrostrictive force, radiation pressure, and the distribution of acoustic and optical modes. It is challenging to obtain the optimal SBS gain coefficient via simple parameter sweeps. In this contribution, we use the genetic algorithm to optimize the suspended phononic crystal Brillouin optical waveguide. The variations of mechanical quality factors and the optical modes are considered to optimize the forward SBS gain. Using this method, we can obtain the optimized waveguide design more simply and accurately. Compared to the previous approaches, the optimized parameters have a 10 percent improvement in the calculated Brillouin gain coefficient.