Bessel beam

About: Bessel beam is a research topic. Over the lifetime, 1946 publications have been published within this topic receiving 42264 citations.

Nondiffracting vortex-beams in a birefringent chiral crystal

Abstract: A vector-wave analysis of nondiffracting beams propagating along a birefringent chiral crystal for the case of tensor character of both the optical activity and linear birefringence is presented. We have written characteristic equations and found propagation constants and amplitude parameters of the eigenmodes. The characteristic curves have anomalous zones described by an isotropic point or a gap-point, provided that the elements of an optical activity tensor obey the requirement g11g33 |g11|. In the anomalous zone, a nondiffracting beam can propagate through a purely chiral crystal as if through an isotropic medium. We have shown that the field of eigenmodes is nonuniformly polarized in the beam cross section, while the field with the initially uniform polarization distribution experiences periodic transformations. We have revealed that even a purely chiral crystal without linear birefringence can generate optical vortices in an initially vortex-free Bessel beam.

On the use of structured light in nonlinear optics studies of the symmetry group of a crystal

Abstract: We put forward a technique that allows to extract information about the symmetry group to which certain nonlinear crystals belong using a single illuminating beam. It provides such information by considering the outcome of a nonlinear optics process characterized by the electric nonlinear susceptibility tensor, whose structure is dictated by such symmetry group. As an example, we consider the process of spontaneous parametric down-conversion, when it is pumped with a special type of Bessel beam. The observation of the spatial angular dependence of the lower-frequency generated light provides direct information about the symmetry group of the crystal. We should stress that the choice of the appropriate illumination is of paramount importance for unveiling the sought-after information.

Creating a three-dimensional surface with antireflective properties by using femtosecond-laser Bessel-beam-assisted thermal oxidation

Abstract: Metal surfaces with low reflectance have received considerable attention for their great optical, electrical, and thermal properties. However, the difficulty in achieving low reflectance on curved metal surfaces has hindered their practical applications. We propose a rapid and flexible method for processing a three-dimensional surface with antireflective properties. A Bessel beam created using an axicon is employed to generate ripple structures on the curved surface, thereby assisting subsequent thermal oxidation. Ripple structures coated with oxide semiconductor nanowires are then processed on a Cu substrate, thus further reducing reflectance. Antireflective properties with a minimum reflectance of less than 0.015 at a wavelength of 500–1200 nm could be achieved by using this method. This presented approach reduces dimensionality in laser processing, subsequently improving processing efficiency, and provides a foundation for the practical application of metal antireflective surfaces.

Propagation of Helmholtz-Gauss beams in absorbing and gain media

Abstract: The propagation of Helmholtz-Gauss beams in media exhibiting loss or gain is studied. The general expressions for the field propagation, the time-averaged power on propagation, the trajectory of the beam centroid, the beam spreading, the nondiffracting distance, and the far field are derived and discussed. Explicit expressions of these parameters for Bessel-Gauss and cosine-Gauss beams are included. The general expressions can be applied straightforwardly to describe the propagation of Mathieu-Gauss and parabolic-Gauss beams in complex media as well.

Bessel beam coherent anti-Stokes Raman scattering microscopy

Abstract: We report about laser scanning coherent anti-Stokes Raman scattering (CARS) microscopy using a Bessel beam to enhance the lateral resolution. This study covers a numerical investigation that predicts an improvement in the lateral resolution by a factor of up to 1.33, while the axial depth of view increases up to a factor of 2 for an ideal Bessel beam serving as both a pump and a probe. Further, we present a simple experimental implementation of a Bessel-like beam by adding only two axicons and a telescope to a conventional CARS laser scanning microscopy setup. The predicted resolution improvement is demonstrated for well-scattering, structured polymer samples.