Ultrafast tunable optical delay in slow light photonic crystal waveguides

We propose a new design for compact tunable optical delay lines, based on adiabatic wavelength conversion and group velocity dispersion, in engineered silicon slow light photonic crystal waveguides. Actuation is performed over a small fraction of the device area, allowing for efficient operation in terms of switching power. We report on the experimental demonstration of variable delays up to 15 ps in a 300 μm long waveguide using this scheme, thus realising an ultrafast tunable delay line in an integrated format.