Arbitrarily accelerating space-time wave packets

TL;DR

This paper demonstrates the synthesis of free-space optical wave packets with customizable acceleration profiles, including arbitrary and composite accelerations, using spectral shaping techniques.

Contribution

It introduces a method to generate space-time wave packets with arbitrary and composite acceleration profiles in free space, surpassing previous constant-acceleration limitations.

Findings

Achieved wave packets with arbitrary axial acceleration profiles.

Demonstrated composite acceleration profiles with acceleration and deceleration phases.

Used spectral shaping to precisely control wave packet dynamics.

Abstract

All known realizations of optical wave packets that accelerate along their propagation axis, such as Airy wave packets in dispersive media or wave-front-modulated X-waves, exhibit a constant acceleration; that is, the group velocity varies linearly with propagation. Here we synthesize space-time wave packets that travel in free space with arbitrary axial acceleration profiles, including group velocities that change with integer or fractional exponents of the distance. Furthermore, we realize a composite acceleration profile: the wave packet first accelerates from an initial to a terminal group velocity, decelerates back to the initial value, and then travels at a fixed group velocity. These never-before-seen optical-acceleration phenomena are all produced using the same experimental arrangement that precisely sculpts the wave packet's spatio-temporal spectral structure.