Bessel beam

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

Underwater acoustic scattering of Bessel beam by spherical shell using T-matrix method

Abstract: The Bessel beam has been proved to show several advantages over the plane wave for its superior characteristics, including nondiffraction and self-reconstruction properties. The Bessel beam is characterized by an important parameter, called the half-conical angle, which describes the angle of the planar wave components of the beam relative to the beam axis. In this research paper, the T-matrix method (TMM) is combined with a Bessel beam to compute the acoustic scattering field. The backscattering form functions of a tungsten carbide sphere and a steel spherical shell are calculated and curved as a function of dimensionless frequency. Several Rayleigh resonance patterns are depicted to further confirm the orders of resonance. By selecting appropriate half-conical angles, several corresponding resonances can be suppressed and this phenomenon may have some potential value in practical applications.

Bessel beam scanning device

Abstract: PURPOSE:To miniaturize a Bessel beam scanning device by converting a light beam having a circular section into a Bessel beam to scan an object, separating the scanning light beam from its reflected light, and converting this reflected light into an electric signal. CONSTITUTION:An axicon lens 12 converts the laser beam L emitted from a beam emitting part 11 and having a circular section into a Bessel beam. A polygon mirror 14 momentarily changes the direction of the light sent from a flat and hollow mirror 13 which reflects the Bessel beam and then scans the surface of a scanning object 1 by the beam L. A hole 17 is formed at the center part of the mirrow 13 that serves as a separating means. Thus the light reflected from the object 1 is reflected again by the mirrow 14 and led to the back of the mirrow 13 through the hole 17. Then this reflected light is condensed on the surface of a photodetector 20 by a condenser lens 18. Therefore the separating means is just required to have such a size that can process the reflected light propagating through the hollow part of the circular light beam. Thus a beam scanning device can be miniaturized.

Micro- and nano-scale photonic lattices induced by Bessel beam technique in doped lithium niobate crystals

Abstract: In this report we present the results of optical induction of 1D and 2D micrometric and sub-micrometric scale annular symmetry photonic lattices in singly and doubly doped photorefractive lithium niobate crystals by Bessel beam technique. The non-diffracting Bessel beam was formed by axicon and the counter-propagating Bessel beam (CPBB) geometry was used to build-up the Bessel standing wave. The cw single mode 532 nm, 17 mW laser beam and 2mm thick lithium niobate (LN) crystals doped by Fe and doubly doped by Fe and Cu with 0,05 w% of impurity ions were used for lattices recording. The crystals with optical C-axes oriented along and perpendicular to the crystal surface (Y-cut and Z-cut LN crystals) were used for photonic lattices recording. The duration of recording was 60 min. 2D photonic lattices formed by CPBB method is a combination of annular and planar gratings and have the periods of 9.0 μm in radial and 266 nm in axial directions. The recorded lattices were tested by diffraction of probe laser beam at 633nm on the lattices. The direct observation of recorded lattices by phase microscope was also performed. The pronounced azimuthal dependence of recorded annular lattices was observed for Y-cut LN crystals. The photonic lattices recorded in LN:Fe:Cu crystals showed high stability against erasure during readout by weak probe beam at the recording wavelength. Under illumination by 2 mW probe green beam the total erasure of the photonic lattice occurred after 8000 sec, which was controlled by measuring the diffracted beam power during readout. The readout destruction of lattices recorded in LN:Fe crystal takes several minutes.

Theory of electromagnetic wave propagation in a longitudinally periodic cylinder

Abstract: Thinking of photonic crystals, we investigate the theory of electromagnetic wave propagation in a perfectly conducting semi-cylinder endowed with a periodic permittivity along its axis while its circular base is illuminated by an harmonic Bessel beam, symmetric around the cylinder axis. We prove that the Floquet-Bessel expansions of electromagnetic fields whose Floquet parts are solutions of a Mathieu equation. is a suitable tool to handle this kind of problems.

Spectral anomalies of diffracted pulsed Bessel beams in dispersive media

Abstract: Starting from the Huygens–Fresnel diffraction integral, the analytical expression for the power spectrum of diffracted pulsed Bessel beams in a dispersive media is derived and used to study the spectral anomalies of pulsed Bessel beams in the far field. Numerical results are given to illustrate the dependence of the anomalous spectral behavior on the pulse parameters, aperture parameter and dispersive properties of the medium. It is shown that, near phase singularities, anomalous spectral behavior may take place. The potential applications of spectral anomalies of ultrashort pulsed beams in information encoding and information transmission are considered.