Linear and angular momenta in tightly focused vortex segmented beams of light (Invited Paper)

Neugebauer, Martin; Aiello, Andrea; Banzer, Peter

doi:10.3788/col201715.030003

Cited by 7 publications

(7 citation statements)

References 39 publications

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“…Thus, the presence of areas in which the total energy flux is directed towards the radiation source can be explained by the fact that the spin flux directed towards the source exceeds in absolute value the orbital energy flux [27]. A negative orbital energy flux was observed in [26]. In an earlier paper [18], we found that regions of reverse energy flux arise not only in the focus plane, but also in planes close to it.…”

Section: Introductionmentioning

confidence: 57%

“…The study in [17] showed that in the Weber modes, the projection of the Poynting vector onto the optical axis takes negative values. The energy flux is the sum of two fluxes: the spin flux and the orbital energy flux [25,26]. Thus, the presence of areas in which the total energy flux is directed towards the radiation source can be explained by the fact that the spin flux directed towards the source exceeds in absolute value the orbital energy flux [27].…”

Section: Introductionmentioning

confidence: 99%

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Toroidal Vortices of Energy in Tightly Focused Second-Order Cylindrical Vector Beams

2021

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In this paper, we simulate the focusing of a cylindrical vector beam (CVB) of second order, using the Richards–Wolf formula. Many papers have been published on focusing CVB, but they did not report on forming of the toroidal vortices of energy (TVE) near the focus. TVE are fluxes of light energy in longitudinal planes along closed paths around some critical points at which the flux of energy is zero. In the 3D case, such longitudinal energy fluxes form a toroidal surface, and the critical points around which the energy rotates form a circle lying in the transverse plane. TVE are formed in pairs with different directions of rotation (similar to optical vortices with topological charges of different signs). We show that when light with a wavelength of 532 nm is focused by a lens with numerical aperture NA = 0.95, toroidal vortices periodically appear at a distance of about 0.45 μm (0.85 λ) from the axis (with a period along the z-axis of 0.8 μm (1.5 λ)). The vortices arise in pairs: the vortex nearest to the focal plane is twisted clockwise, and the next vortex is twisted counterclockwise. These vortices are accompanied by saddle points. At higher distances from the z-axis, this pattern of toroidal vortices is repeated, and at a distance of about 0.7 μm (1.3 λ), a region in which toroidal vortices are repeated along the z-axis is observed. When the beam is focused and limited by a narrow annular aperture, these toroidal vortices are not observed.

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Section: Introductionmentioning

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Toroidal Vortices of Energy in Tightly Focused Second-Order Cylindrical Vector Beams

2021

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“…Therefore, these dynamical characteristics are crucial for understanding the physics behind light-matter interactions with small particles. In the last decade, several theoretical and experimental studies of the dynamical characteristics of various focused beams have been reported, including the fundamental Gaussian beam [31,32], Laguerre-Gaussian (LG) beam [33][34][35], Bessel-Gaussian (BG) beam [36][37][38][39], double-vortex beam [13,14], and other structured light beams [40][41][42][43][44][45][46][47][48]. The LG beam is one of the most well-studied types of structured light beams, both theoretically and experimentally.…”

Section: Introductionmentioning

confidence: 99%

Dynamical characteristics of tightly focused vortex beams with different states of polarization

Cui

Sun

Litchinitser

et al. 2018

J. Opt.

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We report a comparative study of the dynamical characteristics, including the energy, momentum, and angular momentum (AM), of tightly focused vortex beams with different states of polarization. Following Richards and Wolf vectorial diffraction formalism, the electric and magnetic field components of focused vortex beams with linear, circular, radial, and azimuthal polarizations are derived. A general theory to characterize the energy, momentum, spin AM (SAM), and orbital AM (OAM) of tightly focused vortex beams is introduced. Numerical simulations are performed on vortex beams with different polarization states focused by a high NA lens into water. These analytical and numerical studies show that the distributions of field, phase, and dynamical quantities depend on the sign and value of the topological charge carried by the focusing vortex beam, and are strongly affected by the states of polarization. For the vortex beams that do not carry SAM, the change of the sign of the topological charge has no effect on the transverse SAM and OAM, but leads to a reversal of the longitudinal SAM and OAM. For circularly polarized vortex beams, which do carry SAM, the change of the sign of the topological charge has no effect on the longitudinal SAM and transverse OAM, but leads to a redistribution of the transverse SAM and longitudinal OAM. Our results will be useful in revealing the mechanism of spin-orbit interaction within the tightly focused beams and providing new insights into the dynamical properties of focused vortex beams that may be important in applications including optical trapping and micro-manipulation.

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“…Optical cage is a specific kind of optical field that has a dark region surrounded by higher intensity. Owing to its intriguing distribution, an optical cage can be applicable to a multitude of areas, such as optical trapping and manipulation [1][2][3][4][5][6] and optical imaging [7][8][9] . Consequently, the generation of an optical cage has attracted much attention from researchers.…”

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confidence: 99%

Three-dimensional multiple optical cages formed by focusing double-ring shaped radially and azimuthally polarized beams

Zeng¹,

Ding²

2018

Chin. Opt. Lett.

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We propose and simulate a method for generating a three-dimensional (3D) optical cage in the vicinity of focus by focusing a double-ring shaped radially and azimuthally polarized beam. Our study shows that the combination of an inner ring with an azimuthally polarized field and an outer ring with a radially polarized field and a phase factor can produce an optical cage with a dark region enclosed by higher intensity. The shape of the cage can be tailored by appropriately adjusting the parameters of double-mode beams. Furthermore, multiple 3D optical cages can be realized by applying the shift theorem of the Fourier transform and macro-pixel sampling algorithm to a double-ring shaped radially and azimuthally polarized beam.

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Linear and angular momenta in tightly focused vortex segmented beams of light (Invited Paper)

Cited by 7 publications

References 39 publications

Toroidal Vortices of Energy in Tightly Focused Second-Order Cylindrical Vector Beams

Toroidal Vortices of Energy in Tightly Focused Second-Order Cylindrical Vector Beams

Dynamical characteristics of tightly focused vortex beams with different states of polarization

Three-dimensional multiple optical cages formed by focusing double-ring shaped radially and azimuthally polarized beams

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