Angular acceleration with twisted light

TL;DR

This paper demonstrates the first angular acceleration of light using superpositions of Bessel beams with orbital angular momentum, revealing tunable acceleration and energy transfer mechanisms, opening new avenues in optical and matter wave research.

Contribution

It introduces a novel method to achieve and control angular acceleration in light fields through non-canonical Bessel beam superpositions, expanding the scope of accelerating wave packets.

Findings

Angular acceleration of light achieved with Bessel beam superpositions.

Continuous tuning of acceleration and deceleration by adjusting a parameter.

Observation of an unexpected energy transfer mechanism within the field.

Abstract

There is significant interest in tailoring wave packets that transversely accelerate during propagation. The first realisation was in the optical domain, the Airy beam. Valid in the paraxial approximation, such beams were shown to transversely accelerate while following a parabolic caustic, even if the centroid itself travelled along a rectilinear path. Later, non-paraxial optical fields in the form of Weber and Mathieu beams were demonstrated, as well as non-optical wave packets with electrons. Such fields have found a plethora of applications from particle manipulation, spatial-temporal beam control, plasma control to non-linear optics. Here we demonstrate, for the first time, the angular acceleration of light, achieved by non-canonical superpositions of Bessel beams carrying orbital angular momentum. We show that by adjustment of a single parameter the acceleration and deceleration may be tuned continuously. We observe an unexpected energy transfer mechanism between spatial regions of the field which we investigate experimentally and theoretically. Our findings offer a new class of optical field that will enable studies in matter waves and opto-fluidics.