Generation of the second-harmonic Bessel beams via nonlinear Bragg diffraction

TL;DR

This paper demonstrates the generation of conical second-harmonic Bessel beams through nonlinear Bragg diffraction in a specially structured nonlinear crystal, revealing a new method for producing Bessel beams via frequency conversion.

Contribution

It introduces a novel approach to generate second-harmonic Bessel beams using nonlinear Bragg diffraction in a 2D periodically-poled nonlinear photonic structure.

Findings

Conical second-harmonic radiation observed in experiments.

Far-field images correspond to Bessel beams generated in the crystal.

Nonlinear Bragg diffraction effectively produces Bessel beams at the second harmonic.

Abstract

We generate conical second-harmonic radiation by transverse excitation of a two-dimensional annular periodically-poled nonlinear photonic structure with a fundamental Gaussian beam. We show that these conical waves are the far-field images of the Bessel beams generated in a crystal by parametric frequency conversion assisted by nonlinear Bragg diffraction.