Topic
Bessel beam
About: Bessel beam is a research topic. Over the lifetime, 1946 publications have been published within this topic receiving 42264 citations.
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TL;DR: In this article, a method to measure strain at the nanometer scale based on the diffraction of electron Bessel beams is presented, which offers a strain sensitivity better than 2.5 × 10−4 and an accuracy of 1.5× 10−3, competing with or outperforming, the best existing methods with a simple and easy to use experimental setup.
Abstract: Strain has a strong effect on the properties of materials and the performance of electronic devices. Their ever shrinking size translates into a constant demand for accurate and precise measurement methods with a very high spatial resolution. In this regard, transmission electron microscopes are key instruments thanks to their ability to map strain with a subnanometer resolution. Here, we present a method to measure strain at the nanometer scale based on the diffraction of electron Bessel beams. We demonstrate that our method offers a strain sensitivity better than 2.5 × 10−4 and an accuracy of 1.5 × 10−3, competing with, or outperforming, the best existing methods with a simple and easy to use experimental setup.
26 citations
TL;DR: In this paper, the authors proposed a new approach based on Bessel beams that exhibit a focal range exceeding the Rayleigh range by over one order of magnitude, which allows the reliable production of high aspect ratio taper-free microchannels without sample positioning and precise control of translation velocity.
Abstract: Although ultrafast lasers have demonstrated much success in structuring and ablating dielectrics on the micrometer scale
and below, high aspect ratio structuring remains a challenge. Specifically, microfluidics or lab-on-chip DNA sequencing
systems require high aspect ratio sub-10 μm wide channels with no taper. Micro-dicing also requires machining with
vertical walls. Backside water assisted ultrafast laser processing with Gaussian beams allows the production of high
aspect ratio microchannels but requires sub-micron sample positioning and precise control of translation velocity.
In this context, we propose a new approach based on Bessel beams that exhibit a focal range exceeding the Rayleigh
range by over one order of magnitude. An SLM-based setup allows us to produce a Bessel beam with central core
diameter of 1.5 μm FWHM extending over a longitudinal range of 150 μm. A working window in the parameter space
has been identified that allows the reliable production of high aspect ratio taper-free microchannels without sample
translation. We report a systematic investigation of the damage morphology dependence on focusing geometry and
energy per pulse.
26 citations
TL;DR: In this article, the axial and transverse radiation forces on a fluid sphere placed arbitrarily in the acoustical field of Bessel beams of standing waves are evaluated using a partial-wave expansion (PWE) method.
26 citations
TL;DR: It is shown that the output of the OPO has a transverse profile, which is consistent with noncollinear phase-matching relations defined by a conical pump, and Bessel beam pumping was shown to be useful, providing tubular beam coupling into OPO cavity modes.
Abstract: We demonstrate operation of a KTP optical parametric oscillator (OPO) pumped by a Bessel beam for the first time to our knowledge. It is shown that the output of the OPO has a transverse profile, which is consistent with noncollinear phase-matching relations defined by a conical pump. The central spot and ring related to the pair of signal and idler beams were generated in the OPO. By adjusting the OPO cavity mirrors, we easily selected the lowest-order mode as well as the higher-order transverse modes in the central spot. Bessel beam pumping was shown to be useful, providing tubular beam coupling into OPO cavity modes. The OPO threshold pump energy was ~100 muJ in a 6-ns pulse.
26 citations
TL;DR: In this paper, the authors introduced a new family of diffraction-free asymmetric elegant Bessel beams (EB-beams) with fractional orbital angular angular momentum (OAM).
Abstract: This paper introduces a new family of diffraction-free asymmetric elegant Bessel beams (EB-beams) with fractional orbital angular momentum (OAM). EB-beams are modes of free space and described by the n-th order Bessel function of the first kind with a complex argument. Functions of complex amplitudes of EB-beams are orthogonal by co ntinuous scaling parameter and not orthogonal on a discrete parameter (topological charge). The intensity distribution of EB-beams has a countable number of isolated zeros of intensity, located on the horizontal axis. These zeros are centers of optical vortices with unit topological charge and opposite signs on different sides of the origin. Isolated intensity zero on the optical axis generates an optical vortex with topological charge of n . OAM of the EB-beams is ( n + 0,69777)ħ per photon, where ħ is the Planck's constant.
25 citations