Long-Range Hybrid Plasmonic Disk Resonators for mW Bistability and Self-Pulsation

A side-coupled disk-waveguide system based on a long-range hybrid plasmonic waveguiding configuration is theoretically investigated for Kerr bistability and self-pulsation. The nonlinear response is studied with a theoretical framework combining perturbation theory and temporal coupled-mode theory, where all relevant effects, including two-photon absorption (TPA) as well as free-carrier dispersion (FCD) and absorption (FCA), are taken into account. We show that bistable operation with input powers as low as 40 mW is possible; a consequence of the significant reduction in resistive losses made possible by the long-range waveguiding principle. The effect of TPA, FCD, and FCA on the nonlinear response is thoroughly assessed and it is shown that carrier lifetime must drop to 8 ps in order to suppress free-carrier effects and obtain a high-quality bistable response, which is subsequently exploited for demonstrating ultrafast memory operation with low power requirements and high extinction ratio between states. Finally, by appropriate tuning of the carrier lifetime, FCD can lead to self-pulsation. The operating regimes in the detuning-power space are identified and the characteristics of the spontaneous oscillation discussed.