Diffraction-free beams in thin films

TL;DR

This paper investigates the formation of diffraction-free Bessel beams in thin films, presenting a simple model to predict their transverse patterns and discussing potential applications in surface science.

Contribution

It introduces an exact model for diffraction-free waves in thin films, extending understanding of Bessel beam propagation in nano-layered structures.

Findings

Diffraction-free waves can form in thin films with spot sizes near or below the wavelength.

A simple plane-wave model accurately predicts the transverse pattern of these waves.

Potential applications in surface science are proposed.

Abstract

The propagation and transmission of Bessel beams through nano-layered structures has been discussed recently. Within this framework we recognize the formation of unguided diffraction-free waves with the spot size approaching and occasionally surpassing the limit of a wavelength when a Bessel beam of any order n is launched onto a thin material slab with grazing incidence. Based on the plane-wave representation of cylindrical waves, a simple model is introduced providing an exact prescription of the transverse pattern of this type of diffraction-suppressed localized waves. Potential applications in surface science are put forward for consideration.