Controlling and Switching Slow Light in Photonic Crystal Waveguides

Using slow-light photonic crystal waveguides in ultrafast pump-probe experiments, we demonstrate the adiabatic frequency conversion and ultrafast switching of telecoms light pulses on a silicon chip. By storing a 1.3 ps pulse in the slow-light modes of a photonic crystal waveguide, we are able to blue-shift it by 0.3 THz with high (80 efficiency. We show that the shift occurs when the pulse adiabatically follows the modes of the waveguide in which it travels upon these modes being perturbed by the absorption of a pump pulse. We also show rerouting of optical pulses in a bandwidth limited time of just 3ps. The switch is based on coupled W1 photonic crystal waveguides, and the interaction between the waveguide modes is optimised to give an ultra-short (similar to 3 lambda) switching length of just 5 mu m.