An integrable all Optical Switch for Photonic IntegratedCircuits

A completely new model of an all-optical switch (AOS) is proposed using a silicon photonic crystal (PhC) slab based nonlinear Mach–Zehnder interferometer (NMZI). Both arms of the NMZI are designed using p-toluene sulfonate (PTS) based slotted PhC waveguides (PTS-SPCWs). Extreme optical confinement in SPCW is used here to intensify optical nonlinearities of PTS. The intensified nonlinearity produces significant phase changes in optical pulses within a small waveguide length, even when the optical power is sufficiently small. One arm of the NMZI is coupled with a control wave to incur additional phase shift compared to the other due to cross-phase modulation, in addition to self-phase modulation, which is a common phenomenon for both. The differential phase shift originates destructive/constructive interference, leading to a successful switching operation of the AOS. Switching characteristics of the AOS are evaluated for a variety of parameters. A typical example shows that the AOS can switch off 12.55 mW probe power with an extinction ratio of ≈50.5dB by applying 5.65 mW control power, while the device footprint is merely 259µm2. The low-power and high-speed operation makes this small footprint AOS device suitable for applications in photonic integrated circuits.