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: In this article, a leaky radial waveguide consisting of a capacitive sheet over a ground plane that supports higher-order leaky modes is presented. But the authors do not specify the operating bandwidth of the Bessel-beam launch system.
Abstract: We present a Bessel-beam launcher based on a leaky radial waveguide consisting of a capacitive sheet over a ground plane that supports higher-order leaky modes. A propagating Bessel beam is generated above the radiating waveguide. The Bessel beam is transverse-magnetic (TM) polarized with a vertical component of electric field that is a zeroth-order Bessel function of the first kind. A higher-order leaky-wave mode is used to reduce losses at millimeter waves and, at the same time, avoid the thin dielectric layers used in previously proposed lower order leaky-wave Bessel launchers. Closed-form design equations are provided for the proposed structure. In addition, the operating bandwidth of the launcher is defined using dispersion analysis. Near-field measurements of a prototype operating in the frequency range 38–39.5 GHz validate the concept. The measured launcher generates a Bessel beam with a stable spot size of about 4.3 mm ( $0.57\,\lambda$ ) over a nondiffractive range of about 16.4 mm ( $2.2\,\lambda$ ), within about a 4% fractional bandwidth.
53 citations
TL;DR: It is shown that far-field as well as near-field imaging systems beside their spatial frequency filtering ability, also act as polarization filters playing a determinant role on the image structure.
Abstract: In this paper are reported the results concerning the experimental study of the interaction between the vectorial amplitude of an optical field and imaging systems. It is shown that far-field as well as near-field imaging systems beside their spatial frequency filtering ability, also act as polarization filters playing a determinant role on the image structure. This conclusion is drawn from an experimental and theoretical study involving a radially polarized Bessel beam used as a test object.
53 citations
TL;DR: In this article, the superluminal and diffraction-free properties of a Bessel beam with a conical mirror were analyzed in the radial and on-axis dimensions and verified that the central peak does not spread over a propagation distance of 73 cm.
Abstract: We experimentally analyze a Bessel beam produced with a conical mirror, paying particular attention to its superluminal and diffraction-free properties. We spatially characterized the beam in the radial and on-axis dimensions and verified that the central peak does not spread over a propagation distance of 73 cm. In addition, we measured the superluminal phase and group velocities of the beam in free space. Both spatial and temporal measurements show good agreement with the theoretical predictions.
52 citations
TL;DR: In this paper, a novel method is devised for Bessel beam generation in the microwave regime, where the beam is decomposed in terms of a number of guided transverse electric modes of a metallic waveguide.
Abstract: A novel method is devised for Bessel beams generation in the microwave regime. The beam is decomposed in terms of a number of guided transverse electric modes of a metallic waveguide. Modal expansion coefficients are computed from the modal power orthogonality relation. Excitation is achieved by means of a number of inserted coaxial loop antennas, whose currents are calculated from the excitation coefficients of the guided modes. The efficiency of the method is evaluated and its feasibility is discussed. Obtained results can be utilized to practically realize microwave Bessel beam launchers.
52 citations
TL;DR: In this article, a near-field plate that can generate an evanescent Bessel beam is presented, which consists of nonperiodic concentric corrugations that surround a coaxially fed aperture.
Abstract: We present a near-field plate that can generate an evanescent Bessel beam. The metallic plate consists of nonperiodic concentric corrugations that surround a coaxially fed aperture. The design procedure for such a device is outlined. The designed plate is simulated using a full-wave electromagnetic solver and is shown to produce an evanescent Bessel beam, thereby verifying its design and operation. The performance of the near-field plate is contrasted against a coaxial probe and a near-field plate designed to produce an Airy focal pattern with the same beamwidth. Such a device, capable of producing evanescent Bessel beams, will find applications in near-field probing/imaging systems, data storage, and biomedical devices.
52 citations