Manifestation of the Gouy phase in vector-vortex beams

Philip, Geo M.; Kumar, Vijay; Milione, Giovanni; Viswanathan, Nirmal K.

doi:10.1364/ol.37.002667

Cited by 43 publications

(29 citation statements)

References 18 publications

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“…Gouy in the 1890s [1,2], his namesake phase has been observed under a wide variety of circumstances. Recently investigated systems range from vortex beams [3,4] to fields of surface plasmon polaritions [5]. Surprisingly many different explanations for the physical origin of this remarkable effect have been suggested (see [6] and the references therein).…”

Section: Introductionmentioning

confidence: 99%

Manifestation of the Gouy phase in strongly focused, radially polarized beams

Pang¹,

Visser²

2013

Opt. Express

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Abstract:The Gouy phase, sometimes called the focal phase anomaly, is the curious effect that in the vicinity of its focus a diffracted field, compared to a non-diffracted, converging spherical wave of the same frequency, undergoes a rapid phase change by an amount of π. We theoretically investigate the phase behavior and the polarization ellipse of a strongly focused, radially polarized beam. We find that the significant variation of the state of polarization in the focal region, is a manifestation of the different Gouy phases that the two electric field components undergo.

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Section: Introductionmentioning

confidence: 99%

Manifestation of the Gouy phase in strongly focused, radially polarized beams

Pang¹,

Visser²

2013

Opt. Express

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“…Our results make no assumption about the spatial form of the intensity distribution, which need not be limited to beams with constant circular polarization, nor intensity distributions of radial symmetry and simple Gaussian cross-section. It is clear that locally different forces will arise according to the specific beam structure; examples of more intricate behavior may be afforded by vector beams with transverse variations in polarization [28][29][30], which are the subject of ongoing analysis. It is indeed anticipated that beams with spatially varying polarization may enhance the effect of enantiomer separation, especially since such beams are known to engender unusual forces and torques [31].…”

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confidence: 99%

Laser optical separation of chiral molecules

Bradshaw

Andrews

2015

Opt. Lett.

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The optical trapping of molecules with an off-resonant laser beam involves a forward-Rayleigh scattering mechanism. It is shown that discriminatory effects arise on irradiating chiral molecules with circularly polarized light; the complete representation requires ensemble-weighted averaging to account for the influence of the trapping beam on the distribution of molecular orientations. Results of general application enable comparisons to be drawn between the results for two limits of the input laser intensity. It emerges that, in a racemic mixture, there is a differential driving force whose effect, at high laser intensities, is to produce differing local concentrations of the two enantiomers. Trapping of this type usually relates to the interaction of the laser field with a transition electric dipole, as shown by Fig. 1(a). Interactions between the irradiating beam and a transition magnetic dipole are also possible, but the associated coupling strength is usually much smaller in magnitude, and the effects are generally ignored. However, when considering the possibility of chiral discrimination (in which input light of left-handed circular polarization offers different observables compared to right-handed polarization), the conventional trapping mechanism involving only electric dipole transition moments has to be extended to accommodate transition magnetic dipoles [7]. In fact, the forward-Rayleigh scattering events most relevant in chiral discrimination involve a mixture of magnetic and electric dipole interactions, as illustrated by Fig. 1(b), with one kind of coupling involved in the input photon annihilation and the other in the output photon release.To understand the energetics in greater detail, we note that the underlying mechanism for the optical trapping of molecules is based on the variation of intensity within the optical beam, which produces a position-dependent lowering of energy for the molecules it encounters: the alternating electric field of the radiation may be interpreted as producing a dynamic Stark shift to the molecular ground state energy. In terms of quantum electrodynamics, the energy shift (which is quadratically dependent on the electric field of the light) has to originate in forward-Rayleigh scattering, i.e., the concerted annihilation and creation of photons with identical energy and wave-vector. In such a case, the optical wavelengths will lie in a region of transparency for the irradiated molecule-the throughput laser beam therefore emerges unchanged. The primary physical determinant of optical trapping is the potential energy U, whose evaluation from quantum theory requires that the initial and final states (here denoted by I) are identical [8]. An expression for U per molecule is determined from second-order time-dependent perturbation theory, i.e.,where S is an intermediate state of the system comprising both molecule and radiation, E is the energy of the state denoted by its subscript, and H int is the dipolar interaction Hamiltonian given byHere, μ and m are the electric and...

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“…Equation 1 describes a vector beam, [15][16][17] which in the language of quantum mechanics is a hybrid-superposition, a superposition state of A home-made electromagnetic coil is used to apply a longitudinal magnetic field to the warm atomic vapor. We use a resistance wire as a slide rheostat to adjust the coil current to obtain precise settings of the weak magnetic field intensity.…”

Section: 11mentioning

confidence: 99%

Magnetic-field-induced rotation of light with orbital angular momentum

Shi

Ding

Zhou

et al. 2015

Applied Physics Letters

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Light carrying orbital angular momentum (OAM) has attractive applications in the fields of precise optical measurements and high capacity optical communications. We study the rotation of a light beam propagating in warm 87 Rb atomic vapor using a method based on magnetic-fieldinduced circular birefringence. The dependence of the rotation angle on the magnetic field makes it appropriate for weak magnetic field measurements. We quote a detailed theoretical description that agrees well with the experimental observations. The experiment shown here provides a method to measure the magnetic field intensity precisely and expands the application of OAMcarrying light. This technique has advantage in measurement of magnetic field weaker than 0.5Gauss, and the precision we achieved is 0.8 mGauss.

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Manifestation of the Gouy phase in vector-vortex beams

Cited by 43 publications

References 18 publications

Manifestation of the Gouy phase in strongly focused, radially polarized beams

Manifestation of the Gouy phase in strongly focused, radially polarized beams

Laser optical separation of chiral molecules

Magnetic-field-induced rotation of light with orbital angular momentum

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