Spatiotemporal steering of non-diffracting wavepackets

TL;DR

This paper demonstrates how spatiotemporal boundaries can be used to control and engineer the velocity and direction of non-diffracting light bullets, enabling advanced manipulation of electromagnetic wavepackets in space-time.

Contribution

It introduces a novel method of spatiotemporal refraction to convert focused beams into controllable light bullets with programmable dynamics.

Findings

Spatiotemporal refraction can generate light bullets from monochromatic beams.

Designing spatiotemporal boundaries allows control over group velocity and direction.

The effects are exclusive to spatiotemporal boundaries, not achievable with purely spatial or temporal ones.

Abstract

We study the dynamics of space-time non-diffracting wavepackets, commonly known as light bullets, in a spatiotemporally varying medium. We show that by spatiotemporal refraction, a monochromatic focused beam can be converted to a light bullet that propagates at a given velocity. By further designing the index profile of the spatiotemporal boundary, the group velocity and the propagation direction of the light bullet can be engineered in a programmable way. All effects mentioned above cannot be achieved by spatial or temporal boundaries, and are only possible with spatiotemporal boundaries. These findings provide unique ways to engineer the dynamics of electromagnetic wavepackets in space-time. Such wavepackets with engineered spacetime trajectories may find potential applications in the spatiotemporal control of material properties or particles, or for use as a way to emulate relativistic physics in the laboratory.