Topic
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: A gradient acoustic metasurface to manipulate acoustic wavefront freely and some excellent wavefront manipulations are demonstrated by anomalous refraction, non-diffracting Bessel beam, sub-wavelength flat focusing, and effective tunable acoustic negative refraction.
Abstract: We designed a gradient acoustic metasurface to manipulate acoustic wavefront freely. The broad bandwidth and high efficiency transmission are achieved by the acoustic metasurface which is constructed with a series of unit cells to provide desired discrete acoustic velocity distribution. Each unit cell is composed of a decorated metal plate with four periodically arrayed Helmholtz resonators (HRs) and a single slit. The design employs a gradient velocity to redirect refracted wave and the impedance matching between the metasurface and the background medium can be realized by adjusting the slit width of unit cell. The theoretical and numerical results show that some excellent wavefront manipulations are demonstrated by anomalous refraction, non-diffracting Bessel beam, sub-wavelength flat focusing, and effective tunable acoustic negative refraction. Our designed structure may offer potential applications for the imaging system, beam steering and acoustic lens.
48 citations
TL;DR: Simulation results verify the ability of the MS lens to achieve OAM beam focusing, which is advantageous for enhancing the propagation directivity and increasing the gain in the main lobes of vortex waves, of particular importance in microwave wireless communication applications.
Abstract: Vortex electromagnetic (EM) waves hold promise for their ability to significantly increase the transmission capacity of wireless communication systems via the torsion resistance defined by different topological charges associated with the orbital angular momentum (OAM). However, the application of vortex waves in remote distance transmission is limited by its characteristic of divergence. In this paper, a lens based on a phase-modulation metasurface (MS) is proposed that enables vortex EM waves to converge, thereby improving their propagation performance at microwave frequencies. A phase-shift distribution on the plane of the MS is obtained based on the concept of the optical converging axicon, which can convert a Laguerre-Gaussian (LG) beam to a Bessel beam based on changing the propagation direction. Simulation results verify the ability of the MS lens to achieve OAM beam focusing, which is advantageous for enhancing the propagation directivity and increasing the gain in the main lobes of vortex waves. This is of particular importance in microwave wireless communication applications.
48 citations
TL;DR: In this paper, a physical method of generation is proposed in the form of propagation of an ordinary (nonevanescent) Bessel beam across an interface between two different dielectric media.
Abstract: Bessel beams of the evanescent kind are presented and analyzed. They rapidly decay with propagation but retain their original transversal shape. A physical method of generation is proposed in the form of propagation of an ordinary (nonevanescent) Bessel beam across an interface between two different dielectric media. Transmission and reflection coefficients are calculated for this type of beam. The analysis is vectorial and is fully consistent with Maxwell’s equations. Apodized beams of Gauss–Bessel and Circ–Bessel types are propagated by numerical simulation and are shown also to retain a narrow central lobe. Beams of these types have evident advantages in near-field applications, microscopy, and high-density data storage with subwavelength resolution.
48 citations
TL;DR: In this article, the spin and orbital angular momentum (OAM) of a light beam were studied in two different sample chambers with trapped objects in the first chamber acting as distorting obstacles.
Abstract: Propagation through a distorting obstacle may significantly influence the amplitude, phase and polarization state of a light beam. This potentially has consequences for the behaviour of the optical angular momentum of light. We experimentally study how both the spin and orbital angular momentum (OAM) of light behaves upon passage through microscopic optically trapped particles. Particles trapped with Gaussian and, separately, Bessel light beams in two spatially distinct sample chambers are studied with trapped objects in the first chamber acting as distorting obstacles. The Bessel beam can reconstruct its spatial form and this shows reconstruction of both spin and OAM over extended distances.
47 citations
TL;DR: These results allow Mie scattering calculations to be carried out considerably faster than existing methods, something that is of particular interest for time evolution simulations where large numbers of scattering calculations must be performed.
Abstract: Multipole expansions of Bessel and Gaussian beams, suitable for use in Mie scattering calculations, are derived. These results allow Mie scattering calculations to be carried out considerably faster than existing methods, something that is of particular interest for time evolution simulations where large numbers of scattering calculations must be performed. An analytic result is derived for the Bessel beam that improves on a previously published expression requiring the evaluation of an integral. An analogous expression containing a single integral, similar to existing results quoted, but not derived, in literature, is derived for a Gaussian beam, valid from the paraxial limit all the way to arbitrarily high numerical apertures.
47 citations