Asymmetric Fano resonance and bistability in a two-ring resonator optical switch with high extinction ratio and low switching threshold.

We propose a two-ring resonator configuration that can provide optical switching with both high extinction ratio (ER) and low switching threshold. The achievable input threshold is n ₂I_IN ~ 10⁻⁵ or smaller, which is one order lower than that of the conventional one-ring configuration, while maintaining an ER of at least 10dB over a 10-GHz (0.1 nm) optical bandwidth. This performance is enabled by using an asymmetric Fano resonance as opposed to the usual symmetric resonance. The low switching threshold and the high ER are related to the sharpness and the asymmetricity of the Fano resonance, respectively. [ABSTRACT FROM AUTHOR]