T ability to slow and delay optical pulses is intriguing, and has significant applications for telecommunications and other areas. Slow light is usually obtained by having large dispersion over a narrow frequency band. The bandwidth of these systems is therefore limited, leading to pulse broadening in addition to the delay—which imposes a tradeoff between the delay and the system’s bandwidth. We have shown that, by introducing nonlinearity in the slow-light system, a soliton can be formed. The pulse can then travel slowly over arbitrarily long distances without broadening, permitting the generation of arbitrarily large delays. We implement this in a Bragg grating, written in the core of a silica optical fiber. Bragg gratings have a spectral bandgap where light cannot propagate and is strongly reflected. Just outside the bandgap, light propagation is allowed, but the group velocity is drastically reduced, and varies in a narrow spectral window bebroadening is, in principle, limited only by the grating length. The figure shows the time-resolved output intensity when 0.68-ns pulses were launched into a 10-cm fiber Bragg grating at peak powers around 2 kW. The largest delay we obtained was 1.6 ns, or 2.4 3 the input pulse width, corresponding to a group velocity of 0.23 c /n. As the peak power is varied, the delay is tuned because the bandgap wavelength shifts relative to that of the pulse due to nonlinear effects, thereby varying the pulse’s group velocity. The output pulse is narrower than the input pulse, consistent with simulation, indicating dispersion being canceled. Our vision is to implement such a slow-light system in a chalcogenide waveguide. Chalcogenide is a highly nonlinear material that can lower the peak power requirement to a few watts. Chalcogenide glasses also exhibit large photo-induced index changes,3 which permit longer delays in shorter device lengths.4 Furthermore, thermal poling of chalcogenide glass can induce a significant secondorder susceptibility5 that leads to the possibility of electrically tunable delay via the electro-optic effect.6 Since this is a planar geometry, all these features can be implemented in an integrated environment, making the device more compact and easier to control. t