Compact optical switches and modulators based on dispersion engineered photonic crystals

We use slow-light photonic crystals to enhance optical switching and modulation in silicon. By using dispersion-engineered designs, a switch as short as 5 mu m was achieved, in which we have demonstrated rerouting of optical pulses on a 3-ps time scale through the absorption of a femtosecond pulse. We additionally demonstrate a modulator with a Mach-Zehnder interferometer (MZI) configuration with flat-band slow-light photonic crystal phase shifters that is designed to give a large group-index-bandwidth product. An extinction ratio in excess of 15 dB is obtained over the entire 11-nm bandwidth of the modulator.