Bistable action with hybrid plasmonic Bragg-grating resonators

Abstract

Optical bistability with a hybrid silicon–plasmonic configuration consisting of a nonlinear Bragg-grating resonator side-coupled with a bus waveguide is theoretically investigated. The nonlinear response is studied with a modeling framework combining perturbation theory and temporal coupled-mode theory, fed with three-dimensional finite element method simulations. For the CW case, a general closed-form expression describing the nonlinear response is derived, valid for finite intrinsic quality factors and arbitrary coupling conditions. This generalization is necessary for studying plasmonic resonators which are inherently lossy. The effect of the parameters entering in the expression on the bistability curve is thoroughly investigated and the physical system is accordingly designed so as to exhibit minimum power threshold and an extinction ratio between bistable states exceeding 10 dB. Finally, the temporal dynamics are assessed. The system can toggle between bistable states in approximately 2 ps and is thus suitable for ultrafast memory/switching applications.