Engineering the axial intensity of Bessel beams (original) (raw)

Diffractive optics for axial intensity shaping of Bessel beams

Journal of Optics

Bessel beams (BBs) appear to be immune to diffraction over finite propagation distances due to the conical nature of light propagation along the optical axis. This offers promising advantages in laser fabrication. However, BBs exhibit a significant intensity variation along the direction of propagation. We present a simple technique to engineer the axial intensity of the BBs over centimeter-long propagation distances without expansion of the incoming laser beam. This method uses two diffractive optical elements (DOEs), one converts the input Gaussian intensity profile to an intermediate intensity distribution, which illuminates the second DOE, a binary axicon. BBs of a desired axial intensity distribution over a few centimeters length can be generated.

Generating Bessel-Gaussian Beams with Controlled Axial Intensity Distribution

Applied Sciences, 2020

This paper investigated the diffraction of a Gaussian laser beam on a binary mask and a refractive axicon. The principles of the formation of a zero-order Bessel beam with sharp drops of the axial field intensity edges were discussed. A laser optical system based on an axicon for the formation of a Bessel beam with quasi-uniform distribution of axial field intensity was proposed. In the laser optical system, the influence of the axicon apex did not affect the output beam. The results of theoretical and experimental studies are presented. It is expected that the research results will have practical application in optical tweezers, imaging systems, as well as laser technologies using high-power radiation.

Quasi-Bessel beam generated by oblate-tip axicon

2008

We focused here on the real shape of the tip of the axicon - which is not sharp but rather oblate. We simulated numerically and verified experimentally that tiny deviations of the tip shape from the ideal sharp profile induce significant oscillations of the beam intensity along its propagation. Such unwanted intensity modulation disturbs the unique properties of the quasi-Bessel beam - constant shape of the lateral intensity profile and especially slow variation of the on-axis intensity along the beam propagation. We demonstrate how the spatial filtration of the beam in the Fourier plane removes such undesired modulation and restores the properties of the quasi-Bessel beam.

Intrinsically shaping the focal behavior with multi-ring Bessel-Gaussian beam

Applied Physics Letters, 2017

Traditional manipulation of light generally employs diffractive optical elements such as binary phase or amplitude masks. However, we have found that vector Bessel-Gaussian (BG) beams have the intrinsic capacity of forming a special intensity pattern without additional optical elements. Using the vector diffraction theory, we theoretically show that several optical patterns (e.g., hollow beam, bottle beam, optical needle, and spot) can be created only by dynamically tailoring vector BG beams through their beam parameters (viz., polarization order n, transverse wave number b, and beam waist w 0). These results yield a useful guideline for the adjustable beam parameter to generate a certain optical pattern in the focal region. The proposed roadmap of manipulating the structured beams by their intrinsic properties might open an alternative avenue for beam shaping.

Generation of nondiffracting Bessel beams by use of a spatial light modulator

Optics Letters, 2003

A laser beam with phase singularities is an interesting object to study in optics and may have important applications in guiding atoms and molecules. We explore the characteristics of a singularity in a nondiffracting Bessel beam experimentally by use of a programmable spatial light modulator with 64-level phase holograms. The diffraction efficiency with 64-level phase holograms is greatly improved in comparison with that obtained with a binary grating. The experiments show that the size and def lection angle of the beam can be controlled in real time. The observations are in agreement with scalar diffraction theory.

Axial intensity of apertured Bessel beams

Journal of the Optical Society of America A, 1997

We give a simple interpretation of a recently noted phenomenon, namely, the resemblance between the axial intensity of an apertured Bessel beam and the squared profile of the windowing function. We also discuss how this effect can be used to control the axial behavior of the beam, and we present examples for the case of a flattened Gaussian profile as aperturing function.

Beam Shaping Optical Lens Designs for Diffraction-Free Bessel Beams

International Journal of Optics and Photonic Engineering, 2019

Beam shaping technique is applied to design optical lenses for transforming uniform beams to diffraction-free Bessel Beams. One-lens and two-lens refracting system will be demonstrated where the lens' surfaces equations can be easily derived. The designed lenses take the input uniform beam distribution and confine it to be within the main lobe of the Bessel beam and avoid its zeros crossings. Various design parameters such as the power of the beam and the optical system length will be discussed. It will be demonstrated that the two-element design will produce smaller system length than the one-element design.

Intensity Distribution of the Modified Bessel-Gauss Beams

Egyptian Journal of Physics, 2020

T HE intensity of the modified Bessel-Gauss beam (MBGB) was studied at the waist plane and along the longitudinal coordinate (z). Many factors governed the intensity distribution; the radius of the circle produced by the wavevector base at the waist plane (a), the position vector (r), the initial spot size (ω 0) and the longitudinal coordinate (z). The MBGB intensity behavior varied according to the value of a. At a=ω 0 the intensity was almost constant. At a > ω 0 , the intensity increased with increasing r while at a<ω 0 the intensity decreased as the distance r increased. The radius of curvature of the wavefront along z-axis decreased first as the coordinate increased until it reached a minimum value at z min and then slowly increased. The dependences of the MBGB intensity on both a and r at various coordinate z were investigated. At r = 0.2 and 0.5 mm the MBGB intensity continue decreased by the increase of a until it tended to almost zero at values of a greater than 1.5 mm.

Generation of achromatic Bessel beams using a compensated spatial light modulator

Optics Express, 2006

We report the creation of white-light, achromatic Bessel beams using a spatial light modulator and a prism to compensate for the dispersion. Unlike the Bessel beam created by a refractive axicon, this achromatic beam has a radial wavevector and hence an intensity cross-section which is independent of wavelength. The technique also lends itself to the generation of higher order Bessel