On-chip temporal telescope via moving index fronts

We propose a scheme for an on-chip signal pulse compression using a temporal telescope formed by a pump-induced moving refractive index front. To the best of our knowledge, this is the first numerical demonstration of such a concept using moving index perturbations. We numerically study the signal dynamics under the influence of a moving refractive index front in optical waveguides, revealing analogies to relativistic event horizon physics. Our simulations show that a free-carrier-induced refractive index front, which lowers the refractive index and induces a blue shift in the waveguide's band diagram, can overtake and trap a signal pulse, dynamically accelerating it to the front's velocity. As the interaction continues, the signal is eventually released from the front and transitions into a new velocity regime. This process of trapping, acceleration, and release mirrors the behavior of light near gravitational horizons, with the release phase analogous to light escaping a white hole. These results pave the way for new approaches in nonlinear optics and signal processing using compact, chip-scale systems.