Measuring vortex charge with a triangular aperture

Araujo, Luı́s E. E. de; Anderson, Matthew E.

doi:10.1364/ol.36.000787

Cited by 120 publications

(32 citation statements)

References 12 publications

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“…Other methods have also been introduced to measure the OAM of optical vortices based on the diffraction phenomena [12][13][14]. More recently, it has been shown that a triangular aperture illuminated with a vortex beam creates a truncated lattice diffraction pattern and that the resultant diffraction pattern can be used to measure the OAM of light beams [15][16][17]. Other methods for measuring the topological charge of an optical vortex have included the diffraction intensity pattern after an axicon [18] or an annular triangle aperture [19].…”

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confidence: 99%

Measuring the orbital angular momentum of partially coherent optical vortices through singularities in their cross-spectral density functions

2012

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By analysis of the far-field cross-correlation function (CCF) of partially coherent optical beams, we demonstrate an implicit rule that the number of ring dislocations (dark zones) of the far-field CCF is equal to the original topological charge of an optical vortex rendered partially coherent. This novel link between an optical vortex and its correlation singularity may offer an efficient method for measuring the orbital angular momentum of partially coherent optical vortices in fields such as astrophysics and astronomy, as well as atmospheric laser communication.

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Measuring the orbital angular momentum of partially coherent optical vortices through singularities in their cross-spectral density functions

2012

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“…Since Hickmann et al [9], in 2010, unveiled the truncated optical lattice in triangular-aperture diffraction of OAM beams, it has been used as a more effective method for OAM detection. This method is free of complicated interferometer devices and has been successfully used in femtosecond vortices [10], non-integer charge vortices [11], vectorial vortices [12], and elliptical vortex beams [13], which largely promoted the related technologies and applications. Therefore, it is very significant to fulfill the technical breakthrough by more characteristic structured lights for extending more novel applications.…”

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confidence: 99%

Truncated triangular diffraction lattices and orbital-angular-momentum detection of vortex SU(2) geometric modes

Shen¹,

Fu²,

Gong³

2018

Opt. Express

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We for the first time report the truncated diffraction with a triangular aperture of the SU(2) geometric modes and propose a method to detect the complicated orbital angular momentum (OAM) of an SU(2) wave-packet, to the best of our knowledge. As a special vortex beam, a nonplanar SU(2) mode carrying special intensity and OAM distributions brings exotic patterns in truncated diffraction lattice. A meshy structure is unveiled therein by adjusting the illuminated aperture in vicinity of the partial OAM regions, which can be elaborately used to evaluate the partial topological charge and OAM of an SU(2) wave-packet by counting the dark holes in the mesh. Moreover, through controlling the size and position of the aperture at the center region, the truncated triangular lattice can be close to the classical spot-array lattice for measuring the center OAM. These effects being fully validated by theoretical simulations greatly extend the versatility of topological structures detection of special beams.

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“…Furthermore, quite a few ways have been presented to measure the topological charge value of vortex beams161718192021222324. Generally, the light beams carrying OAM can be detected directly by observing the interference patterns.…”

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confidence: 99%

“…For instance, the measurement of the topological charge value of an optical vortex beam was reported by analyzing the interference pattern between a vortex beam and its mirror image16. A triangular aperture was also used for the measurement of vortex beams, which could be up to l = ± 71718. Through the diffraction intensity pattern after an annular aperture, the measurement of the topological charge value of an optical vortex beam was also up to | l| = 919.…”

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Measuring Orbital Angular Momentum (OAM) States of Vortex Beams with Annular Gratings

Zheng

Wang

2017

Sci Rep

113

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Measuring orbital angular momentum (OAM) states of vortex beams is of great importance in diverse applications employing OAM-carrying vortex beams. We present a simple and efficient scheme to measure OAM states (i.e. topological charge values) of vortex beams with annular gratings. The magnitude of the topological charge value is determined by the number of dark fringes after diffraction, and the sign of the topological charge value is distinguished by the orientation of the diffraction pattern. We first theoretically study the diffraction patterns using both annular amplitude and phase gratings. The annular phase grating shows almost 10-dB better diffraction efficiency compared to the annular amplitude grating. We then experimentally demonstrate the OAM states measurement of vortex beams using annular phase grating. The scheme works well even for high-order vortex beams with topological charge value as high as ± 25. We also experimentally show the evolution of diffraction patterns when slightly changing the fractional topological charge value of vortex beam from 0.1 to 1.0. In addition, the proposed scheme shows potential large tolerance of beam alignment during the OAM states measurement of vortex beams.Angular momentum can be divided into spin angular momentum (SAM) and orbital angular momentum (OAM) in paraxial beams, which are related to circular polarization and spatial distribution, respectively. In 1992, Allen and coworkers recognized that helically phased beams comprising an azimuthal phase term exp(ilϕ), have an OAM of lħ per photon, where l is topological charge value, ϕ is azimuthal angle, and ħ is Plank's constant h divided by 2π1 . In recent years, optical beams carrying OAM (i.e. OAM modes), also referred to as vortex beams, have attracted more and more attention owing to their distinct characteristics such as the phase singularity at the beam center and the resultant doughnut shape intensity profiles. OAM modes with different topological charge value l, are theoretically unbounded and orthogonal to each other. Similar to other mode bases in free space or fiber, OAM modes are another basis with which to represent spatial modes. Different mode bases including OAM modes can be employed in mode-division multiplexing (MDM), which a subset of space-division multiplexing (SDM). Very recently, OAM modes have shown great potential for MDM both in free space and fiber-based optical communications [2][3][4][5] . Vortex beams or OAM modes also provide unique opportunities for manipulation of micro-/nano-particles as it asserts torque in addition to forces related to optical intensity gradient, giving rise to orbital and spin movements beyond trapping. Remarkably, for diverse applications of vortex beams in optical communications 2-5 , optical tweezers 6,7 , optical trapping 8 and quantum information technology 9 , an accurate measurement of the topological charge values of vortex beams, which includes the magnitude and the sign, is of great importance.Until now, a wide variety of methods have been proposed t...

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Measuring vortex charge with a triangular aperture

Cited by 120 publications

References 12 publications

Measuring the orbital angular momentum of partially coherent optical vortices through singularities in their cross-spectral density functions

Measuring the orbital angular momentum of partially coherent optical vortices through singularities in their cross-spectral density functions

Truncated triangular diffraction lattices and orbital-angular-momentum detection of vortex SU(2) geometric modes

Measuring Orbital Angular Momentum (OAM) States of Vortex Beams with Annular Gratings

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