Optical switching using nonlinear polarization rotation inside silicon waveguides

We study the nonlinear polarization rotation induced by a pump pulse on a probe beam through cross-phase modulation inside a silicon waveguide and show that this phenomenon can be used to realize a fast Kerr shutter in spite of the free-carrier effects and walk-off. We show that free carriers generated by the pump pulse through two-photon absorption affect the switching process considerably, especially with the interaction of walk-off effects. However, numerical simulations reveal that their impact is not detrimental for short pump pulses. In this case, an approximate analytical solution predicts the shape and duration of the switching window with reasonable accuracy.