Fast light in silicon ring resonator with resonance-splitting

We report experimental demonstration of fast light in an over-coupled ultra-compact silicon ring resonator with resonance-splitting. Strong mutual-coupling induced by the grating inside the ring leads to split resonances and accompanying large anomalous dispersion, thus providing a new approach to realizing fast light in the over-coupled region of the ring resonator. In the experiment, a maximum pulse advancement of 130 ps with low distortion is achieved for a 1-ns signal pulse in a 10-mum-radius silicon ring resonator. The observed pulse advancement agrees well with the theoretical calculation based on coupled mode theory.