Propagation-invariant strongly longitudinally polarized toroidal pulses

TL;DR

This paper introduces strongly longitudinally polarized toroidal pulses with a dominant longitudinal field component, exhibiting nondiffracting propagation and potential applications in advanced microscopy, communication, and light-matter interactions.

Contribution

The authors develop a new class of propagation-invariant toroidal pulses with dominant longitudinal polarization, surpassing previous transverse-focused fields in magnitude and stability.

Findings

Longitudinal component exceeds transverse by over tenfold.

SLPTPs exhibit nondiffracting, robust propagation.

Potential applications in microscopy and wireless communication.

Abstract

Recent advancements in optical, terahertz, and microwave systems have unveiled non-transverse optical toroidal pulses characterized by skyrmionic topologies, fractal-like singularities, space-time nonseparability, and anapole-exciting ability. Despite this, the longitudinally polarized fields of canonical toroidal pulses notably lag behind their transverse counterparts in magnitude. Interestingly, although mushroom-cloud-like toroidal vortices with strong longitudinal fields are common in nature, they remain unexplored in the realm of electromagnetics. Here, we present strongly longitudinally polarized toroidal pulses (SLPTPs) which boast a longitudinal component amplitude exceeding that of the transverse component by over tenfold. This unique polarization property endows SLPTPs with robust propagation characteristics, showcasing nondiffracting behavior. The propagation-invariant strongly longitudinally polarized field holds promise for pioneering light-matter interactions, far-field superresolution microscopy, and high-capacity wireless communication utilizing three polarizations.