All-optical switch and digital light processing using photonic crystals

We have demonstrated all-optical switching operations by coupled resonator-waveguide systems in two-dimensional Si-based photonic crystals. These systems operate at extremely low power and with a very high switching speed compared with conventional devices using the same nonlinear mechanism due to title use of an ultrasmall resonator with a high quality factor. We also describe an all-optical sequential circuit composed of two resonant tunneling filters. Using a two-dimensional FDTD (finite-difference time-domain) calculation, we numerically demonstrate that an optical digital circuit can synchronize input data with its clock.