Nondiffracting Beams With Finite Beam Width

Since Durnin reported the first experiment of Bessel beams, the related researchwork has developed extensively because of their 'nondiffracting' property andinteresting potential applications. It was shown that nearly nondiffracting Besselbeams can be realized experimentally by using various methods, such as an annularslit system, holographic amplification, an F-P interferometer, axicon and refractingsystem. This note presents the investigation results of the authors on nondiffractingBessel beams with finite beam width, i.e. beams limited by an aperture. Experimentshave been performed to illustrate the advantages of generating Bessel beams with anaxicon. A detailed study of the axial intensity and maximum nondiffracting range ofBessel beams vs. aperture size, and the conversion efficiency of the axicon as a Besselbeam convertor has been given. Within the experimental errors the result are ingood agreement with the theory.

Generation of shaping nondiffracting structured caustic beams on the basis of stationary phase principle

On the basis of the stationary phase principle,we construct a family of shaping nondiffracting structured caustic beams with the desired morphology.First,the analytical formula of a nondiffracting astroid caustic is derived theoretically using the stationary phase method.Then,several types of typical desired caustics with different shapes are numerically simulated using the obtained formulas.Hence,the key optical structure and propagation characteristics of nondiffracting caustic beams are investigated.Finally,a designed phase plate and an axicon are used to generate the target light field.The experimental results confirm the theoretical prediction.Compared with the classical method,the introduced method for generating nondiffracting caustic beams is high in light-energy utilization;hence,it is expected to be applied conveniently to scientific experiments.

A Note on Self-Accelerating Olver and Olver-Gauss Beams

The recent introduction by Belafhal et al. [Opt. and Photon. J. 5, 234-246 (2015)] of mth-order Olver beams as a novel class of self-accelerating nondiffracting solutions to the paraxial equation is a direct contradiction to the seminal work of Berry and Balazs who determined that the infinite-energy Airy wave packet is the only accelerating nondiffracting solution to the (1 + 1)D Schrödinger equation. It is shown in this note that the work of Belafhal et al. is valid only for m=0, which coincides with the Airy solution.

Ultracompact phase plate fabricated by femtosecond laser two-photon polymerization for generation of Mathieu–Gauss beams

The Mathieu beam is a typical nondiffracting beam characterized by its propagation invariance and self-reconstruction.These extraordinary properties have given rise to potentialities for applications such as optical communications,optical trapping,and material processing.However,the experimental generation of Mathieu–Gauss beams possessing high quality and compactness is still challenging.In this work,even and helical Mathieu phase plates with different orders m and ellipticity parameters q are fabricated by femtosecond laser two-photon polymerization.The experimentally generated nondiffracting beams are propagationinvariant in several hundred millimeters,which agree with numerical simulations.This work may promote the miniaturization of the application of nondiffracting beams in micronanooptics.

Specially shaped Bessel-like self-accelerating beams along predesigned trajectories

Over the past several years, spatially shaped self-accelerating beams along different trajectories have been studied extensively. Due to their useful properties such as resistance to diffraction, self-healing, and selfbending even in free space, these beams have attracted great attention with many proposed applications. Interestingly, some of these beams could be designed with controllable spatial profiles and thus propagate along various desired trajectories such as parabolic, snake-like, hyperbolic, hyperbolic secant, three-dimensional spiraling, and even self-propelling trajectories. Experimentally, suchbeams are realized typically by using a spatial light modulator so as to imprint a desired phase distribution on a Gaussian-like input wave front propagating under paraxial or nonparaxial conditions. In this paper, we provide a brief overview of our recent work on specially shaped self-accelerating beams, including Bessel-like, breathing Bessellike, and vortex Bessel-like beams. In addition, we propose and demonstrate a new type of dynamical Bessel-like beams that can exhibit not only self-accelerating but also self-propelling during propagation. Both theoretical and experimental results are presented along with a brief discussion of potential applications.

Self-healing of holographically generated moirélattice wave fields

Self-healing in optics generally refers to the ability to reconstruct itself and restore the original state after encountering obstacles in the propagation of the light field.In this research,we observe the processes of the wave fields from perfect to defect in front of the focal plane of the 4f system,finally returning to an intact situation after the plane.According to simulations and experimental results,there is a minimum self-healing distance for the moirélattice field that positively associates with the radius of the defect[obstacle]in the nondiffracting transmission range.Furthermore,it is observed that the defect self-healing is a process of“repairing the center and then repairing the edges.”These findings can be applied in areas such as optical imaging,capture,and information processing.