Compact optical switches and modulators based on dispersion engineered photonic crystals

Liam O'Faolain, University of St Andrews
Daryl M. Beggs, University of St Andrews
Thomas P. White, University of St Andrews
Tobias Kampfrath, FOM Institute for Atomic and Molecular Physics - AMOLF
Kobus Kuipers, FOM Institute for Atomic and Molecular Physics - AMOLF
Thomas F. Krauss, University of St Andrews


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 μm 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. © 2009 IEEE.