Controlling the velocity of ultrashort light pulses in vacuum through spatio-temporal couplings

TL;DR

This paper presents a theoretical study on how combining temporal chirp and longitudinal chromatism in ultrashort laser beams allows precise control of their intensity peak velocity in vacuum, enabling advanced applications like laser-driven particle acceleration.

Contribution

It introduces a novel method to control the velocity of ultrashort laser pulse peaks using spatio-temporal couplings in a linear medium.

Findings

Velocity of intensity peaks can be arbitrarily set within the Rayleigh length.

Spatio-temporal couplings enable precise control of pulse propagation.

Potential applications include improved laser-matter interaction control.

Abstract

Due to their broad spectral width, ultrashort lasers provide new possibilities to shape light beams and control their properties, in particular through the use of spatio-temporal couplings. In this context, we present a theoretical investigation of the linear propagation of ultrashort laser beams that combine temporal chirp and a standard aberration known as longitudinal chromatism. When such beams are focused in a vacuum, or in a linear medium, the interplay of these two effects can be exploited to set the velocity of the resulting intensity peak to arbitrary values within the Rayleigh length, i.e. precisely where laser pulses are generally used. Such beams could find groundbreaking applications in the control of laser-matter interactions, in particular for laser-driven particle acceleration.