Active control of slow light on a chip with photonic crystal waveguides

Abstract

It is known that light can be slowed down in dispersive materials near resonances¹. Dramatic reduction of the light group velocity—and even bringing light pulses to a complete halt—has been demonstrated recently in various atomic^2,3,4,5 and solid state systems^6,7,8, where the material absorption is cancelled via quantum optical coherent effects^3,4,5,7. Exploitation of slow light phenomena has potential for applications ranging from all-optical storage to all-optical switching^9,10. Existing schemes, however, are restricted to the narrow frequency range of the material resonance, which limits the operation frequency, maximum data rate and storage capacity¹⁰. Moreover, the implementation of external lasers, low pressures and/or low temperatures prevents miniaturization and hinders practical applications. Here we experimentally demonstrate an over 300-fold reduction of the group velocity on a silicon chip via an ultra-compact photonic integrated circuit using low-loss silicon photonic crystal waveguides^11,12 that can support an optical mode with a submicrometre cross-section^13,14. In addition, we show fast ( ∼ 100 ns) and efficient (2 mW electric power) active control of the group velocity by localized heating of the photonic crystal waveguide with an integrated micro-heater.