Photon orbital angular momentum in a plasma vortex (original) (raw)

Photon orbital angular momentum and mass in a plasma vortex

EPL (Europhysics Letters), 2010

We analyse the Anderson-Higgs mechanism of photon mass acquisition in a plasma and study the contribution to the mass from the orbital angular momentum acquired by a beam of photons when it crosses a spatially structured charge distribution. To this end we apply Proca-Maxwell equations in a static plasma with a particular spatial distribution of free charges, notably a plasma vortex, that is able to impose orbital angular momentum (OAM) onto light. In addition to the mass acquisition of the conventional Anderson-Higgs mechanism, we find that the photon acquires an additional mass from the OAM and that this mass reduces the Proca photon mass.

Experimental verification of photon angular momentum and vorticity with radio techniques

Applied Physics Letters, 2011

The experimental evidence that radio techniques can be used for synthesizing and analyzing non-integer electromagnetic (EM) orbital angular momentum (OAM) of radiation is presented. The technique used amounts to sample, in space and time, the EM field vectors and digitally processing the data to calculate the vortex structure, the spatial phase distribution, and the OAM spectrum of the radiation. The experimental verification that OAM-carrying beams can be readily generated and exploited by using radio techniques paves the way to an entirely new paradigm of radar and radio communication protocols.

Radio beam vorticity and orbital angular momentum

2011

It has been known for a century that electromagnetic fields can transport not only energy and linear momentum but also angular momentum. However, it was not until twenty years ago, with the discovery in laser optics of experimental techniques for the generation, detection and manipulation of photons in well-defined, pure orbital angular momentum (OAM) states, that twisted light and its

Spatiotemporal vortex beams and angular momentum

We present a space-time generalization of the known spatial (monochromatic) wave vortex beams carrying intrinsic orbital angular momentum (OAM) along the propagation direction. Generic spatio-temporal vortex beams are polychromatic and can carry intrinsic OAM at an arbitrary angle to the mean momentum. Applying either (i) a transverse wave-vector shift or (ii) a Lorentz boost to a monochromatic Bessel beam, we construct a family of either (i) time-diffracting or (ii) non-diffracting spatio-temporal Bessel beams, which are exact solutions of the Klein-Gordon wave equations. The proposed spatio-temporal OAM states are able to describe either photon or electron vortex states (both relativistic and nonrelativistic), and can find applications in particle collisions, optics of moving media, quantum communications, and astrophysics.

Propagation of vortex electron wave functions in a magnetic field

Physical Review A, 2012

The physics of coherent beams of photons carrying axial orbital angular momentum (OAM) is well understood and such beams, sometimes known as vortex beams, have found applications in optics and microscopy. Recently electron beams carrying very large values of axial OAM have been generated. In the absence of coupling to an external electromagnetic field the propagation of such vortex electron beams is virtually identical mathematically to that of vortex photon beams propagating in a medium with a homogeneous index of refraction. But when coupled to an external electromagnetic field the propagation of vortex electron beams is distinctly different from photons. Here we use the exact path integral solution to Schrodingers equation to examine the time evolution of an electron wave function carrying axial OAM. Interestingly we find that the nonzero OAM wave function can be obtained from the zero OAM wave function, in the case considered here, simply by multipling it by an appropriate time and position dependent prefactor. Hence adding OAM and propagating can in this case be replaced by first propagating then adding OAM. Also, the results shown provide an explicit illustration of the fact that the gyromagnetic ratio for OAM is unity. We also propose a novel version of the Bohm-Aharonov effect using vortex electron beams.

Manifestation of the rotational Doppler effect by use of an off-axis optical vortex beam

Optics Letters, 2003

We report the first all-optical detection of the frequency beats between Gaussian and Laguerre-Gaussian LG 0 1 mode in their coherent axial superposition, caused by the rotational Doppler effect. The relation of equivalence between the observable off-axis optical vortex rotation and the rotational frequency shift of the Laguerre-Gaussian component is ascertained. The obtained results can be used as a physical basis for LG modes spectrum recognition along their orbital angular momentum. The optics of wave fields possessing phase singularities has opened a new chapter in modern optics. 1 A common phase singularity (screw wavefront dislocation) looks like a helical surface, and the helicoid winding number m (positive or negative integer) is referred to as the topological charge. 2 For instance, Laguerre-Gaussian (LG) modes LG p l with nonzero index l have phase dependence in the form exp(il -ikz), which provides a helical shape for the wavefronts (z is the longitudinal coordinate,  is the azimuth angle in the transverse plane, k is the wavenumber).

Transverse optical current in off-axis vortex beams

Asian Journal of Physics, 2021

Dedicated to Professor D N Rao for his significant contributions and pioneering works in the fields of spectroscopy, optics, nonlinear optics and photonics Optical beams nesting single or more off-axial distribution of point vortices is considered. The effective topological charge carried out by the beam is explored when the beam is nesting a fractional order vortex phase, beam containing an arbitrary distribution of point vortices as well as when two or more integer order vortex fields are superposed. The orbital angular momentum (OAM) carried out by this beam is generally a fractional number when average OAM per photon is considered. Depending on the distribution of the point vortices the beam may carry a net transverse linear momentum which dictates the nature of the OAM carried out by the beams. When more than one off-axis vortex is present within the beam, the transverse Poynting vector also exhibits saddle points which reveal intricate topological structure of such optical vortex beams.

Relativistic electron vortex beams in a laser fi eld

The orbital angular momentum Hall e ffect and spin Hall eff ect of electron vortex beams (EVB) have been studied for the EVBs interacting with laser field. In the scenario of paraxial beam, the cumulative e ffect of the orbit-orbit interaction of EVBs and laser fields drives the orbital Hall e ffect, which in turn produces a shift of the center of the beam from that of the fi eld-free case towards the polarization axis of photons. Besides, for non-paraxial beams one can also perceive a similar shift of the center of the beam owing to spin Hall eff ect involving spin-orbit interaction. Our analysis suggests that the shift in the paraxial beams will always be larger than that in non-paraxial beams.