Space-time wave packets violate the universal relationship between angular dispersion and pulse-front tilt

TL;DR

This paper demonstrates that space-time wave packets break the universal relationship between angular dispersion and pulse-front tilt, showing non-differentiable angular dispersion and bandwidth-dependent pulse-front tilt in optics.

Contribution

It reveals that space-time wave packets violate the established universal relationship, introducing non-differentiable angular dispersion in optical pulses.

Findings

Space-time wave packets violate the universal angular dispersion-pulse-front tilt relationship.

They exhibit non-differentiable angular dispersion.

Pulse-front tilt depends on bandwidth even at fixed angular dispersion.

Abstract

Introducing angular dispersion into a pulsed field tilts the pulse front with respect to the phase front. There exists between the angular dispersion and the pulse-front tilt a universal relationship that is device-independent, and also independent of the pulse shape and bandwidth. We show here that this relationship is violated by propagation-invariant space-time (ST) wave packets, which are pulsed beams endowed with precise spatio-temporal structure corresponding to a particular form of angular dispersion. We demonstrate theoretically and experimentally that underlying ST wave packets is -- to the best of our knowledge -- the first example in optics of non-differentiable angular dispersion, resulting in pulse-front tilt that depends on the pulse bandwidth even at fixed angular dispersion.