Pulse-Self-Steepening via Optical Push Broom

We demonstrate, through numerical simulations, an on-chip time lens and pulse self-steepening effect based on the optical push broom mechanism. A fast Kerr-induced refractive index front, generated within an optical waveguide, collects, traps, and concentrates the energy of a signal pulse propagating with a smaller group velocity, tuned near the bandgap of the periodically modulated waveguide. The high energy of the initial low-peak-power signal pulse accumulates within the front. This concentrated energy itself modifies the front and further steepens the leading edge of the signal pulse. The demonstrated effect can be utilized to compress signals in time and generate highly steep refractive index fronts.