Pulse Compression by an Optical Push Broom On a Chip

TL;DR

This paper demonstrates a novel optical pulse compression technique using a moving refractive index front in a silicon waveguide, enabling light trapping and stopping without reflection, with experimental validation and theoretical modeling.

Contribution

First experimental demonstration of pulse compression via a moving refractive index front in a silicon waveguide, introducing the optical push broom effect.

Findings

Successful experimental pulse compression and light trapping.

Reproduction of frequency shift corresponding to temporal delay.

Validation of theoretical model with experimental results.

Abstract

In this study, we report a first experimental demonstration of pulse compression by a gradual refractive index front moving in a periodically modulated silicon waveguide, the so-called optical push broom effect. Optical push broom captures and confines the input signal pulse in a faster propagating refractive index front, driven by a pump pulse. This is a spatio-temporal analogue of light trapping in a tapered plasmonic waveguide where light is continuously changing its wavevector approaching zero group velocity and, thus, stopped without reflection. Here the signal is accelerated by the front until the signal velocity matches the front velocity, thus stopping the light in respect to the front. We employ the slowly varying envelope approximation to model this phenomenon. Notably, we well reproduced the experimental frequency shift at the output corresponding to the temporal delay at the input.