Direct acceleration of electrons using two crossed Laguerre-Gaussian laser beams in vacuum

The basic physical characteristics of electrons accelerated by two linearly polarized and circularly symmetric crossed Laguerre-Gaussian （LG） laser beams with equal frequency and amplitude in vacuum are studied in detail. The condition, under which electrons can be accelerated effectively, and the energy gain are discussed.

Average Capacity of OAM-Multiplexed FSO System with Vortex Beam Propagating Through Non-Kolmogorov Turbulence

The propagation of vortex beam in atmospheric turbulence is of significant importance in theoretical study and practical applications. Based on extended Huygens-Fresnel integral and the Rytov approximation, the average capacity of orbital angular momentum(OAM)-multiplexed Laguerre-Gaussian(LG) beam propagating through non-Kolmogorov turbulence is presented, and the analytical expression of spiral spectrum of LG beam has been deduced. The average capacity of FSO system is numerically calculated and the influence of exponent parameter, transmission height, structure constant, wavelength, outer scale and inner scale on average capacity are also analyzed in detail. Outcomes show that smaller structure constant, outer scale, higher transmission height and larger wavelength, inner scale are conducive to improve average capacity in different extent. Results acquires in this paper have potential application value in optical communication within non-Kolmogorov turbulence.

Composite optical vortices in noncollinear Laguerre–Gaussian beams and their propagation in free space

Taking two Laguerre-Gaussian beams with topological charge 1 = ±1 as an example, this paper studies the composite optical vortices formed by two noncollinear Laguerre-Gaussian beams with different phases, amplitudes, waist widths, off-axis distances, and their propagation in free space. It is shown by detailed numerical illustrative examples that the number and location of composite vortices at the waist plane are variable by varying the relative phase β, amplitude ratio η, waist width ratio ξ, or off-axis distance ratio μ. The net topological charge lnet is not always equal to the sum lsum of charges of the two component beams. The motion, creation and annihilation of composite vortices take place in the free-space propagation, and the net charge during the propagation remains unchanged and equals to the net charge at the waist plane.

Study on holographic grating diffraction for Laguerre–Gaussian beam generation

Laguerre-Gaussian beams, as a special model with spiral phase structure, have been intensively investigated. Holographic grating method is a convenient method of generating Laguerre-Gaussian beams and measuring their orbital angular momenta. But due to some inevitable adverse factors such as lateral displacement, angular deflection and elliptical incident profile of incident beam, the practical effectiveness should be reevaluated. This paper is devoted to the study on the influences of the abovementioned three adverse factors on the holographic grating method. The characteristics of the mode decomposition of diffractive order and the relative powers of the orbital angular momentum eigen-states are also given.

Approximate analytical expressions of apertured broadband beams in the far field

The approximate analytical expressions of the apertured broadband beams in the far field with Gaussian and Laguerre-Gaussian spatial modes are presented. For the radially polarized Laguerre-Gaussian beam, the result reveals that the electromagnetic field in the far field is transverse magnetic. The influences of bandwidth （Г） and truncation parameter （Co） on the transverse intensity distribution of the Gaussian beam and on the energy flux distribution of radially polarized Laguerre-Gaussian beam are analysed.

Generation of Laguerre-Gaussian beam from end-pumped and c-cut Nd:YVO_4 laser

We demonstrate an end-pumped, c-cut Nd：YVO4 laser that emitted first-order Laguerre-Gaussian （LGol） beam by adjusting the position of focused pump beam relative to laser crystal. The pumping light reached the laser crystal has circular and solid intensity profile. The laser is compact and stable, and the obtained LG01 beam power reaches 202 mW with -25% slope efficiency.

Additive Manufacturing of Metal Micro-ring and Tube by Laser-Assisted Electrophoretic Deposition with Laguerre-Gaussian Beam

We report a method for laser-assisted electrophoretic deposition using a Laguerre-Gaussian beam for maskless patterning of metal rings and tubes.These are structures of utmost importance,particularly in photonic devices.Metal nanoparticles,which are gathered in a colloidal solution by a laser trapping technique,are deposited on a substrate via electrophoresis.The deposition pattern is dependent on the focused spot shape during laser trapping.The intensity distribution of the Laguerre-Gaussian beam is ring-shaped.Rings with different inner diameters can be fabricated by varying the topological charge of the Laguerre-Gaussian beam.The equivalent inner diameters of the deposited rings with topological charges of 1,3,and 5 were 0.30,0.78,and 1.45μm,respectively.The inner diameter of the deposited ring with a topological charge of 1 was smaller than the wavelength of the laser beam(532 nm).A tube was also fabricated with a topological charge of 3 by vertical displacement of the deposition cell.The deposition technology developed here using Laguerre-Gaussian beam will contribute to advancements in the fabrication of photonic and nano-fluidic devices.