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Bessel beam
About: Bessel beam is a research topic. Over the lifetime, 1946 publications have been published within this topic receiving 42264 citations.
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TL;DR: The experimental results are in good agreement with the simulations using semi-classical theory of SR together with spatial self-phase modulation (SPM), indicating that the transverse effect of SR is mainly attributed to its propagation in the nonlinear medium.
Abstract: We report on the investigation on the transverse effect of superradiation (SR) in Rb atomic medium by analyzing and comparing the diffraction patterns in the far-field under the circumstances that Gaussian and Bessel beam are taken as the excitation respectively. It is found that Gaussian SR shows a ring-pattern and its beam profile is closely dependent on the incident power and position of the sample cell. The experimental results are in good agreement with the simulations using semi-classical theory of SR together with spatial self-phase modulation (SPM), indicating that the transverse effect of SR is mainly attributed to its propagation in the nonlinear medium. By contrast, the beam profile of Bessel SR is hardly influenced by the input power thanks to its non-diffraction property. The comparison further confirms that the transverse effect of the SR is the result of the nonlinear effect for SR. This work provides useful information in understanding the physics behind the transverse effect of SR, which would be of significance in the applications of SR, such as enhancement on the beam quality and efficiency of the SR sources.
21 Apr 2016
TL;DR: In this article, a linearly-polarized asymmetric Bessel beam with a crescent profile was investigated numerically and experimentally, and it was shown that a binary zone plate of numerical aperture NA = 0.995 forms a cresent in the focal plane, which is rotated clockwise around the optical axis, moving away from the focal planes.
Abstract: Tight focusing of a linearly-polarized asymmetric Bessel beam, which has a crescent profile, was investigated numerically and experimentally. FDTD calculations show that a binary zone plate of numerical aperture NA = 0.995 forms a crescent in the focal plane, which is rotated clockwise around the optical axis, moving away from the focal plane. Using the Debye formulae it was shown that a direction of polarization of incident light has a significant influence on intensity distribution in focal plane. The crescent in the focal plane was also observed experimentally by focusing of the asymmetric Bessel beam using an immersive objective (NA = 1.25).
21 Oct 2004
TL;DR: In this paper, the authors studied the property of propagation beams disturbed by an opaque obstacle and reported the observation of two shadow produced by the obstacle, and the fact that the Bessel beam is formed of ingoing and outgoing conical waves.
Abstract: We study the property of propagation beams disturbed by an opaque obstacle. The fronts of the Hankel waves are disturbed and beyond the obstacle they are reconstructed. We report the observation of two shadow produced by the obstacle, and the fact that the Bessel beam is formed of ingoing and outgoing conical waves. We numerically solve the Helmholtz equation to show the evolution and the reconstruction of the Bessel beam and we demonstrate the correspondence of these results with the experimental part.
01 Jun 2017
TL;DR: In this paper, the authors presented a method to generate the third harmonic of the 1030 nm femtosecond laser (343 nm) and convert the Gaussian laser beam to a Bessel beam.
Abstract: Recently, graphene has attracted wide attentions for its unique properties in optics and electronics. Many excellent designs were proposed base on the structured graphene such as modulators, optical polarizers and limiters [1]. Thus, the fabrication ability of graphene structures can be thought as the cornerstone of the development of the graphene optical and electrical devices. The common used methods include laser direct writing (LDW), focus ion beam etching, electron beam lithography and etc. Among them, LDW was considered as one of the most valuable methods for its non-mask and no secondary deposition. Many efforts were made to improve the resolution and the precision of the LDW fabrication. However, the results are not very ideal. As far as we know, the best achievement was presented by R. Sanin. et al [2]. They generate the third harmonic of the 1030 nm femtosecond laser (343 nm) and convert the Gaussian laser beam to a Bessel beam. 480 nm average width ablation lines with precision ±80 nm were achieved by adjusting the laser power and the scanning speed. However, this width doesn't break the diffraction limit of the laser.