scholarly journals Experimental investigation on optical vortex tweezers for microbubble trapping

Open Physics ◽  
2018 ◽  
Vol 16 (1) ◽  
pp. 383-386 ◽  
Author(s):  
Xiaoming Zhou ◽  
Ziyang Chen ◽  
Zetian Liu ◽  
Jixiong Pu
Keyword(s):  
Optical Tweezers ◽  
Laser Power ◽  
Topological Charge ◽  
Force Measurement ◽  
Numerical Aperture ◽  
Optical Vortex ◽  
Gradient Force ◽  
Vortex Beam ◽  
Trapping Forces ◽  
Topological Charges

AbstractIn this paper, we investigated the microbubble trapping using optical vortex tweezers. It is shown that the microbubble can be trapped by the vortex optical tweezers, in which the trapping light beam is of vortex beam. We studied a relationship between the transverse capture gradient force and the topological charges of the illuminating vortex beam. For objective lenses with numerical aperture of 1.25 (100×), the force measurement was performed by the power spectral density (PSD) roll-off method. It was shown that transverse trapping forces of vortex optical tweezers increase with the increment of the laser power for fixed topological charge. Whereas, the increase in the topological charges of vortex beam for the same laser power results in the decrease of the transverse trapping forces. The experimental results demonstrated that the laser mode (topological charge) has significant influence on the lateral trapping force.

Multi-channeled vortex beam switch with moiré metasurfaces

2021 ◽  
Author(s):  
Cheng Cui ◽  
Zheng Liu ◽  
Bin Hu ◽  
Yurong Jiang ◽  
Juan Liu
Keyword(s):  
Functional Diversity ◽  
Optical Communications ◽  
Topological Charge ◽  
Signal Transmission ◽  
Polarized Light ◽  
Vortex Beam ◽  
Practical Applications ◽  
Linearly Polarized ◽  
Vortex Beams ◽  
Topological Charges

Abstract Tunable metasurface devices are considered to be an important link for metasurfaces to practical applications due to their functional diversity and high adaptability to the application scenarios. Metasurfaces have unique value in the generation of vortex beams because they can realize light wavefronts of any shape. In recent years, several vortex beam generators using metasurfaces have been proposed. However, the topological charge generally lacks tunability, which reduces the scope of their applications. Here, we propose an active tunable multi-channeled vortex beam switch based on a moiré structure composed of two cascaded dielectric metasurfaces. The simulation results show that when linearly polarized light with a wavelength of 810 nm is incident, the topological charge from -6 to +6 can be continuously generated by relatively rotating the two metasurfaces. Meanwhile, different topological charges are deflected to different spatial channels, realizing the function of multi-channeled signal transmission. We also study the efficiency and broadband performance of the structure. The proposed multi-channeled separation method of vortex beams that can actively tune topological charges paves the way for the compactness and functional diversity of devices in the fields of optical communications, biomedicine, and optoelectronics.

scholarly journals Strongly Focused Circularly Polarized Optical Vortices Regulated by a Fractal Conical Lens

2019 ◽  
Vol 10 (1) ◽  
pp. 28
Author(s):  
Zhirong Liu ◽  
Kelin Huang ◽  
Anlian Yang ◽  
Xun Wang ◽  
Philip H. Jones
Keyword(s):  
Angular Momentum ◽  
Optical Tweezers ◽  
Numerical Aperture ◽  
Optical Element ◽  
Optical Vortex ◽  
Optical Vortices ◽  
Circularly Polarized ◽  
Strong Focusing ◽  
New Type ◽  
Vortex Beams

In this paper, a recently-proposed pure-phase optical element, the fractal conical lens (FCL), is introduced for the regulation of strongly-focused circularly-polarized optical vortices in a high numerical aperture (NA) optical system. Strong focusing characteristics of circularly polarized optical vortices through a high NA system in cases with and without a FCL are investigated comparatively. Moreover, the conversion between spin angular momentum (SAM) and orbital angular momentum (OAM) of the focused optical vortex in the focal vicinity is also analyzed. Results revealed that a FCL of different stage S could significantly regulate the distributions of tight focusing intensity and angular momentum of the circularly polarized optical vortex. The interesting results obtained here may be advantageous when using a FCL to shape vortex beams or utilizing circularly polarized vortex beams to exploit new-type optical tweezers.

scholarly journals Spiral phase plate with multiple singularity centers

2020 ◽  
Vol 44 (6) ◽  
pp. 901-908
Author(s):  
V.V. Kotlyar ◽  
A.A. Kovalev ◽  
E.S. Kozlova ◽  
A.P. Porfirev
Keyword(s):  
Topological Charge ◽  
Beam Power ◽  
Phase Plate ◽  
Circular Aperture ◽  
Vortex Beam ◽  
Finite Radius ◽  
Phase Singularity ◽  
Initial Plane ◽  
Topological Charges ◽  
Spiral Phase

We investigate a multispiral phase plate (MSPP) with multiple centers of phase singularity arbitrarily located in the MSPP plane. Equations to describe the topological charge of an optical vortex in the initial plane immediately behind the MSPP and orbital angular momentum (OAM) normalized relative to the beam power are derived. The topological charge in the initial plane is found as a sum of the topological charges of all singularities if their centers are located inside a finite-radius circular aperture. If the phase singularity centers are partially located on the boundary of a circular diaphragm limiting the MSPP, the total topological charge is found as the sum of all singularities divided by 2. Total OAM that the vortex carries depends on the location of the singularity centers: the farther from the center of the plate the singularity center is located, the smaller is its contribution to the OAM. If all singularity centers are located on the boundary of the diaphragm limiting MSPP, then the OAM of the vortex beam equals zero, although in this case the topological charge of the beam is nonzero.

scholarly journals The transition from a coherent optical vortex to a Rankine vortex: beam contrast dependence on topological charge

2016 ◽  
Vol 63 (sup3) ◽  
pp. S51-S56 ◽  
Author(s):  
Ermes Toninelli ◽  
Reuben S. Aspden ◽  
David Phillips ◽  
Graham M. Gibson ◽  
Miles J. Padgett
Keyword(s):  
Topological Charge ◽  
Optical Vortex ◽  
Vortex Beam ◽  
Rankine Vortex

Evaluation of a Trapping Potential Measurement Technique for Optical Tweezers Using Simulations and Experiments

2009 ◽  
Author(s):  
Arvind Balijepalli ◽  
Thomas W. LeBrun ◽  
Jason J. Gorman ◽  
Satyandra K. Gupta
Keyword(s):  
Optical Tweezers ◽  
Measurement Method ◽  
Force Measurement ◽  
Optical Trap ◽  
Two Dimensions ◽  
Trapping Potential ◽  
Potential Measurement ◽  
Trapping Force ◽  
Dynamics Simulations ◽  
Trapping Forces

A technique to measure the trapping force in an optical tweezers, without making any prior assumptions about the trap shape, has been extended to two-dimensions. The response of a trapped micro or nanoparticle to a step input is measured and then used to calculate the trapping force experienced by the particle as a function of its position in the trap. Langevin dynamics simulations have been implemented to evaluate the performance of this measurement method in two-dimensions and to evaluate whether the particle’s motion away from the measurement plane due to diffusion gives rise to an error in the trapping force measurement. Preliminary experimental results are also presented to demonstrate this method in the laboratory. This force measurement method provides insight into the trapping behavior of micro and nanoparticles in an optical trap beyond the region, close to the trap center, where the trapping force is assumed to vary linearly with the particle’s displacement. The measured trapping forces, from simulations and laboratory experiments, are then integrated to recover the shape of the optical trapping potential.

Nanometric plasmonic optical trapping on gold nanostructures

2019 ◽  
Vol 86 (3) ◽  
pp. 30501
Author(s):  
Domna G. Kotsifaki ◽  
Mersini Makropoulou ◽  
Alexander A. Searfetinides
Keyword(s):  
Optical Tweezers ◽  
Single Molecule ◽  
Optical Trapping ◽  
Numerical Aperture ◽  
Resonance Wavelength ◽  
Objective Lens ◽  
Plasmonic Nanostructures ◽  
Theoretical Support ◽  
Trapping Force ◽  
Trapping Forces

The precise noninvasive optical manipulation of nanometer-sized particles by evanescent fields, instead of the conventional optical tweezers, has recently awaken an increasing interest, opening a way for investigating phenomena relevant to both fundamental and applied science. In this work, the optical trapping force exerted on trapped dielectric nanoparticle was theoretically investigated as a function on the trapping beam wavelength and as a function of several plasmonic nanostructures schemes based on numerical simulation. The maximum optical trapping forces are obtained at the resonance wavelength for each plasmonic nanostructure geometry. Prominent tunabilities, such as radius and separation of gold nanoparticles as well as the numerical aperture of objective lens were examined. This work will provide theoretical support for developing new types of plasmonic sensing substrates for exciting biomedical applications such as single-molecule fluorescence.

scholarly journals Effect of Deformation on Topological Properties of Cobalt Monosilicide

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 143
Author(s):  
Sergey Nikolaev ◽  
Dmitry Pshenay-Severin ◽  
Yuri Ivanov ◽  
Alexander Burkov
Keyword(s):  
Band Structure ◽  
Ab Initio Calculations ◽  
Topological Charge ◽  
External Stress ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Topological Properties ◽  
Uniaxial Deformation ◽  
Band Crossing ◽  
Topological Charges

Recently, it was shown that materials with certain crystal structures can exhibit multifold band crossings with large topological charges. CoSi is one such material that belongs to non-centrosymmetric space group P213 (#198) and posseses multifold band crossing points with a topological charge of 4. The change of crystal symmetry, e.g., by means of external stress, can lift the degeneracy and change its topological properties. In the present work, the influence of uniaxial deformation on the band structure and topological properties of CoSi is investigated on the base of ab initio calculations. The k·p Hamiltonian taking into account deformation is constructed on the base of symmetry consideration near the Γ and R points both with and without spin-orbit coupling. The transformation of multifold band crossings into nodes of other types with different topological charges, their shift both in energy and in reciprocal space and the tilt of dispersion around nodes are studied in detail depending on the direction of uniaxial deformation.

Sign in / Sign up

Export Citation Format

Share Document