Bessel beam

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

Generation of high peak power, segmented and Bessel beams of tunable range without on-axis intensity modulation

Abstract: We propose and experimentally demonstrate a novel experimental scheme to generate high peak power, segmented, smooth, zero-order Bessel beams with tunable range. Illuminating the axicon with hollow Gaussian beams (HGBs) of different orders we have generated Bessel beams of varying range at different positions away from the axicon. The presence of dark core at the center of the HGBs removes the effect of imperfection in the axicon tip. As a result, the entire power of the input beam is transformed into zero-order Bessel beam without any on-axis intensity modulation. We observe the decrease in range and increase in peak power of the zero-order Bessel beam with the order of HGBs. Controlling the superposition of the HGBs of different orders to the axicon we have demonstrated the increase in the range of the Bessel beam. The current technique can also produce Bessel beams of different intensity distribution including single peak or multiple peak Bessel beams. Using single-pass second harmonic generation in nonlinear crystals of different lengths we have further verified the increase of peak power of the Bessel beam with the order of the HGBs and also the increase in the range of the Bessel beam due to the superposed HGBs. The generic experimental scheme can be used at different wavelengths and timescales (continuous-wave to ultrafast).

Measuring the scale factor of digital micromirror devices using Bessel beams

Abstract: We determine the scale factor of a digital micromirror device (DMD) with the use of Bessel beams. The scale factor is the value related to how much a device stretches an image along a certain axis. In this paper, we have uploaded slits of varying scale factor s in the DMD and obtained the diffraction patterns formed by illuminating it. The structural shape and the line scan measurements of the captured images were compared to that of a numerically simulated image. Results show that the beam profiles generated with slits of s = 1.87 ± 0.03 have 5% deviation from the numerically simulated Bessel beam profile. This study is proof-of-principle that structured light can be used as tool for measuring the scale factor of a device.

Simplified Generation of High-Angular-Momentum Light Beams

Abstract: A simplified method of generating a beam of light having a relatively high value of angular momentum (see figure) involves the use of a compact apparatus consisting mainly of a laser, a whispering- gallery-mode (WGM) resonator, and optical fibers. The method also can be used to generate a Bessel beam. ( Bessel beam denotes a member of a class of non-diffracting beams, so named because their amplitudes are proportional to Bessel functions of the radii from their central axes. High-order Bessel beams can have high values of angular momentum.) High-angular-momentum light beams are used in some applications in biology and nanotechnology, wherein they are known for their ability to apply torque to make microscopic objects rotate. High-angular-momentum light beams could also be used to increase bandwidths of fiber-optic communication systems. The present simplified method of generating a high-angular-momentum light beam was conceived as an alternative to prior such methods, which are complicated and require optical setups that include, variously, holograms, modulating Fabry-Perot cavities, or special microstructures. The present simplified method exploits a combination of the complex structure of the electromagnetic field inside a WGM resonator, total internal reflection in the WGM resonator, and the electromagnetic modes supported by an optical fiber. The optical fiber used to extract light from the WGM resonator is made of fused quartz. The output end of this fiber is polished flat and perpendicular to the fiber axis. The input end of this fiber is cut on a slant and placed very close to the WGM resonator at an appropriate position and orientation. To excite the resonant whispering- gallery modes, light is introduced into the WGM resonator via another optical fiber that is part of a pigtailed fiber-optic coupler. Light extracted from the WGM resonator is transformed into a high-angular- momentum beam inside the extraction optical fiber and this beam is emitted from the polished flat output end. By adjusting the geometry of this apparatus, it is possible to generate a variety of optical beams characterized by a wide range of parameters. These beams generally have high angular momenta and can be of either Bessel or Bessel-related types.

Generation of high-order Bessel beams by focusing vortex beams with an axicon

Abstract: In this paper the generation of highorder Bessel beams by focusing the vortex beams with an axicon is presented.The intensity distribution of vortex beams after being focused by the axicon was simulated.It is shown that after being focused by the axicon,a vortex beam can be converted into the high order Bessel beam.Moreover,the order of the Bessel beam is equal to the topological charge number of the vortex beam.The generation of the high order Bessel beam was also experimentally investigated.The axicons with different cone angles were employed to focus the vortex beam,and the influence of cone angle of the axicon on the high order Bessel beam was investigated.The experimental results show that in the maximum distance of non-diffraction zone of the axicon,the achieved high order Bessel beam coincides with the theoretically calculated results.