Design and simulation of silicon microring optical routing switches

Using two-dimensional (2-D) scattering matrix theory, the switching behavior of inplane waveguided 2 × 2 resonant optical switches in silicon-on-insulator was analyzed at the 1.33, 1.55, and 10.6 μm wavelengths. The switch consisted of two straight bus waveguides coupled independently and laterally to a pair of microring resonators. Switching actuated by a Δn + iΔκ~ complex index perturbation of the rings was investigated. The switching effects discussed include the free-carrier-plasma dispersion, Franz-Keldysh, quantum-confined Stark, Kerr, and thermooptic effects. Each effect has its Δκ~/Δn signature. For waveguides ≤0.3λ wide, an optimum switch design was determined in the weak coupling regime. Complete switching was found for Δn∼2×10^-3, together with significant modulation for Δn in the 10^-4 range.