Optical solitons in a silicon waveguide

We observe, for the first time to our knowledge, the formation of optical solitons inside a short silicon waveguide (only 5 mm long) at subpicojoule pulse energy levels. We measure a significant spectral narrowing in the anomalous-dispersion regime of such a waveguide, in contrast to all previous reported experiments. The extent of spectral narrowing depends on the carrier wavelength of input pulses, and the observed spectrum broadens in the normal-dispersion region. Numerical simulations confirm our experimental observations.