Genetic optimization of Brillouin scattering gain in subwavelength-structured silicon membrane waveguides

TL;DR

This paper introduces a genetic algorithm-based optimization method combined with subwavelength structuring to significantly enhance Brillouin gain in silicon waveguides, advancing integrated optomechanics for communications and sensing.

Contribution

It presents a novel design strategy that simultaneously engineers photonic and phononic modes in silicon waveguides to maximize Brillouin gain.

Findings

Achieves predicted Brillouin gain over 3300 1/(W m).

Design enables strong photon-phonon interactions in a compact structure.

Optimized geometry requires only a single etch step.

Abstract

On-chip Brillouin optomechanics has great potential for applications in communications, sensing, and quantum technologies. Tight confinement of near-infrared photons and gigahertz phonons in integrated waveguides remains a key challenge to achieving strong on-chip Brillouin gain. Here, we propose a new strategy to harness Brillouin gain in silicon waveguides, based on the combination of genetic algorithm optimization and periodic subwavelength structuration to engineer photonic and phononic modes simultaneously. The proposed geometry is composed of a waveguide core and a lattice of anchoring arms with a subwavelength period requiring a single etch step. The waveguide geometry is optimized to maximize the Brillouin gain using a multi-physics genetic algorithm. Our simulation results predict a remarkable Brillouin gain exceeding 3300 1/(W m), for a mechanical frequency near 15 GHz.