Engineering the optical vacuum: Arbitrary magnitude, sign, and order of dispersion in free space using space-time wave packets

TL;DR

This paper demonstrates a method to precisely control and engineer arbitrary dispersion profiles in free space using space-time wave packets, enabling independent tuning of dispersion orders without losses, surpassing limitations of traditional optical materials.

Contribution

The authors introduce a novel approach to manipulate dispersion in free space via space-time wave packets with non-differentiable angular dispersion, allowing independent control of dispersion orders.

Findings

Arbitrary dispersion profiles can be realized in free space.

Dispersion orders are independently addressable using the proposed method.

The technique enables dispersion values unattainable in conventional optical materials.

Abstract

Spatial structuring of an optical pulse can lead in some cases upon free propagation to changes in its temporal profile. For example, introducing conventional angular dispersion into the field results in the pulse encountering group-velocity dispersion in free space. However, only limited control is accessible via this strategy. Here we show that precise and versatile control can be exercised in free space over the dispersion profile of so-called `space-time' wave packets: a class of pulsed beams undergirded by non-differentiable angular dispersion. This abstract mathematical feature allows us to tune the magnitude and sign of the different dispersion orders without introducing losses, thereby realizing arbitrary dispersion profiles, and achieving dispersion values unattainable in optical materials away from resonance. Unlike optical materials and photonic structures in which the values of the different dispersion orders are not independent of each other, these orders are addressable separately using our strategy. These results demonstrate the versatility of space-time wave packets as a platform for structured light and point towards their utility in nonlinear and quantum optics.