Article

Efficient Sorting of Orbital Angular Momentum States of Light

Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands.
Physical Review Letters (Impact Factor: 7.51). 10/2010; 105(15):153601. DOI: 10.1103/PhysRevLett.105.153601
Source: PubMed

ABSTRACT

We present a method to efficiently sort orbital angular momentum (OAM) states of light using two static optical elements. The optical elements perform a Cartesian to log-polar coordinate transformation, converting the helically phased light beam corresponding to OAM states into a beam with a transverse phase gradient. A subsequent lens then focuses each input OAM state to a different lateral position. We demonstrate the concept experimentally by using two spatial light modulators to create the desired optical elements, applying it to the separation of eleven OAM states.

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    • "a more efficient method is to use wave front transformation from Cartesian to log-polar coordinate [20]. After transformation, the azimuthal phase profile of an OAM mode is mapped to a tilted planner wavefront. "
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    ABSTRACT: Efficiently discriminating beams carrying different orbital angular momentum (OAM) is of fundamental importance for various applications including high capacity optical communication and quantum information processing. We design and experimentally verify a distinguished method for effectively splitting different OAM-carried beams by introducing Dove prisms in a ring cavity. Because of rotational symmetry broken of two OAM-carried beams with opposite topological charges, their transmission spectra will split. When mode and impedance matches between the cavity and one OAM-carried beam are achieved, this beam will transmit through the cavity, and other beam will be reflected without being destroyed their spatial shapes. In this case, the cavity acts like a polarized beam splitter. The transmitting beam can be selected at your will. The splitting efficiency can reach unity if the cavity is lossless and it completely matches with the beam. Beams carry multi-OAMs can also be effectively split by cascading ring cavities.
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    • "Considerable interest in studying optical orbital angular momentum (OAM) arises from its potential applications in quantum information processing, atomic manipulation, micromanipulation , and biosciences [25] [26] [27] [28] [29]. Control of the local spin angular momentum (SAM) and OAM flux density in the the field cross section of a laser beam is important in these applications, since the different values of the local SAM and OAM flux densities lead to different rotations in manipulating particles, and the opposite values of the local SAM and OAM flux densities are associated to opposite circular polarization and opposite vortex topological charges. "
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    ABSTRACT: The propagation dynamics of a vector field with inhomogeneous states of polarization (SoP) imposed a vortex is studied using the angular spectrum method. The evolution of SoP in the cross section of the field during propagation is analyzed numerically by the Stokes polarization parameters. The results indicate that SoP in the field cross section rotate along the propagation axis during propagation due to the existence of a vortex. In addition, the interaction between the phase singularity and the polarization singularity leads to the creation or annihilation of the optical field in the central region. In particular, the distributions of the transverse energy flow and both spin and orbital optical angular momentum fluxes in the cross section of the vortex vector optical field depend sensitively on both the vortex and polarization topology charges.
    Full-text · Article · Jun 2015 · Journal of optics
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    • "The second one is diffraction-based schemes [26] [27] [28] [29] [30] [31] [32] [33] [34] in which the diffraction pattern of the photons through an obstacle is observed. "
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    ABSTRACT: Determination of the orbital angular momentum (OAM) of vortex beams has been hotly discussed. We propose a new type of method to determine the orbital angular momentum of photons, filtering. We present an OAM filter scheme which consists of a cavity with a polarization-based Mach-Zehnder interferometer inside. Our scheme can purify the specific OAM with unitary efficiency theoretically without the pre-knowledge of the OAM spectrum of the input light. We also implemented a proof-of-principle experiment to demonstrate the feasibility of our scheme by cascading three interferometers. Our method offers a new way to determine the OAM spectrum of a light and this method can also be exploited to prepare the eigenstate of vortex beams.
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