Enhanced spatiotemporal optical vortices and vortex chains from Hermite-Gauss modes with a tilted pulse front

TL;DR

This paper demonstrates that focusing a pulsed Hermite-Gauss beam with a tilted pulse front creates enhanced elliptical spatiotemporal optical vortices and vortex chains, with improved properties for advanced photonic applications.

Contribution

It introduces a novel method to generate enhanced elliptical STOVs and vortex chains using tilted pulse fronts with Hermite-Gauss beams, simplifying previous techniques.

Findings

Generation of elliptical STOVs with additional spatial chirp

Enhanced transverse orbital angular momentum in the vortices

Significantly larger longitudinal field compared to normal STOVs

Abstract

Hermite-Gaussian (HG) beams are standard modes delivered by continuous or pulsed lasers systems, and pulse-front tilt is one of the most common, detrimental or beneficial, spatiotemporal couplings affecting ultrashort pulses. Combining them, we show that focusing a pulsed HG beam with a tilt generates an elliptical spatiotemporal optical vortex (STOV), or a chain of them. The elliptical STOVs differ from standard STOVs in an additional spatial chirp that is manifested as a wave front temporal rotation, and results in an enhanced transverse orbital angular momentum. The longitudinal field is significantly larger than that of normal STOVs, and may also take the form of an elliptical STOV. Our concept greatly simplifies previous arrangements for the generation of STOVs, whose additional features make them attractive for improving their applications in electron trapping and acceleration, or as driving fields for the generation of higher-order harmonics and other interactions with matter.