Bessel beam

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

Generation and control of multiple Bessel beams for optical micromanipulation

Abstract: In the area of optical micro-manipulations Bessel beams are well known for their unique properties such as non-diffracting propagation over a large area or their ability to reconstruct themselves after passing a disturbing obstacle. In this paper we demonstrate how the spatial spectrum phase modulation of such Bessel beam can be used for its precise three-dimensional position control or even splitting it in several parallel Bessel beams. Applying these features to a simple computer-driven interactive setup enabled us to guide selected particles between remote planes demonstrating the possibility of active sorting of micro-objects. In the case of two axially shifted co-axial Bessel beams a system of counter-propagating Bessel beams can be obtained using a mirror. The interference of such counter-propagating beams provide a standing-wave axial modulation of the field intensity. The position of this standing wave peaks can be controlled altering phase of one of the beams leading to the concept of an ’Optical conveyor belt’ for transport of micro-objects. However, using a time-sharing between the two beams causes that the interference is suppressed, but their correct axial overlap assures a stable position for object confinement. This geometry can be used then for real-time interactive three-dimensional position control of several objects. Such light fields have broader applications, for example in two-photon processes in biophysics such as photoporation of living cells providing transport of modified DNA from surrounding medium inside the cell volume and consequent synthesis of fluorescent protein.

Comparison of propagation of apertured Bessel and Gaussian beams

Abstract: Ideal Bessel beam is a non-diffracting beam and the most attractive property of such beam is non-diffracting propagation. In optics, although the comparisons of maximum propagation distance had been done between Bessel and Gaussian beams by Durnin and Sprangle, respectively, their comparison results are conflict result from their different criteria. It is necessary and significant that the comparison is carried out at microwave band. In this paper, we therefore propose a relatively objective and just comparison criterion at millimeter wavelength, and numerical simulation results and a new conclusion are presented.

Simulation of turbulence

Abstract: The linear theory of propagation of a spherical wave layer is used to treat the principles of simulating turbulent process and the criteria of its similarity. The mechanism of turbulence is given for a flat channel defined by two walls and for a square tube. We use this channel as an example to demonstrate the effect of the wave layer properties on velocity pulsations, as well as the effect of the characteristics of a sequence of disturbances on the structure of pulsations. The model is used to describe the structure of a plasma channel developed by a Bessel beam of laser radiation. The Mathematica-4 language is used for simulation.

Femtosecond Laser Bessel Beam Fabrication of a Supercapacitor with a Nanoscale Electrode Gap for High Specific Volumetric Capacitance.

Abstract: Supercapacitors are widely used in electronic systems as energy storage devices. The fabrication of a miniaturized supercapacitor with high specific capacitance has attracted much attention in recent years. Here, we propose a new method to fabricate supercapacitors with a nanoscale electrode gap by using a femtosecond laser. The original femtosecond laser was converted to a nondiffraction Bessel light field with nanoscale beam width and microscale focal depth. Nanoscale processing precision was achieved by regulating the Bessel beam. We fabricated graphene supercapacitors with different electrode gap widths (varying from the microscale to the nanoscale) using this method. Supercapacitors fabricated by this method have advantages in both size miniaturization (electrode gap width down to ∼500 nm) and electrochemical performance improvement (a specific volumetric capacitance of 195 F/cm3). This work demonstrates that the femtosecond laser Bessel beam processing method provides a reliable pathway to fabricate miniaturized supercapacitors with high specific capacitance and other nanoscale electronic devices.

Method and device for acquiring Bessel beam based on cross phase modulation

Abstract: The invention discloses a method and device for acquiring a Bessel beam based on cross phase modulation The method comprises the steps that (1) a modulation laser beam is focused in a nonlinear medium; (2) the modulated laser beam enters the same nonlinear medium in a reverse and co-linear manner, and then is made to enter an imaging device; (3) light intensity of the modulated laser beam is adjusted till an obvious center bright spot and an obvious concentric circle pattern appear on the imaging device which is located in a remote field; and (4) a focal distance of a focusing lens or the position of the nonlinear medium is adjusted, so the Bessel beam with the different center bright spot size can be obtained The method disclosed by the invention has the advantages of a simple structure, easy operations and controllability of the center bright spot size