Simplified measurement of the orbital angular momentum of single photons (original) (raw)
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Optics express, 2010
In this paper we show that an optical setup based on a polarizing Sagnac interferometer combined with a Dove prism can be used as a convenient general-purpose tool for the generation, detection and sorting of spin-orbit states of light. This device can work both in the classical and in the quantum single-photon regime, provides higher sorting efficiency and extinction ratio than usual hologram-fiber combinations, and shows much higher stability and ease of alignment than Mach-Zehnder interferometer setups. To demonstrate the full potential of this setup, we also report some demonstrative experiments of several possible applications of this setup.
Near-Perfect Sorting of Orbital Angular Momentum and Angular Position States of Light
2012
Abstract: We present a novel method for efficient sorting of photons prepared in states of orbital angular momentum (OAM) and angular position (ANG). A log-polar optical transform is used in combination with a holographic beam-splitting method to achieve better mode discrimination and reduced cross-talk than reported previously. Simulating this method for 7 modes, we have calculated an improved mutual information of 2.43 bits/photon and 2.29 bits/photon for OAM and ANG modes respectively.
Single-shot measurement of the orbital-angular-momentum spectrum of light
Nature communications, 2017
The existing methods for measuring the orbital-angular-momentum (OAM) spectrum suffer from issues such as poor efficiency, strict interferometric stability requirements, and too much loss. Furthermore, most techniques inevitably discard part of the field and measure only a post-selected portion of the true spectrum. Here, we propose and demonstrate an interferometric technique for measuring the true OAM spectrum of optical fields in a single-shot manner. Our technique directly encodes the OAM-spectrum information in the azimuthal intensity profile of the output interferogram. In the absence of noise, the spectrum can be fully decoded using a single acquisition of the output interferogram, and, in the presence of noise, acquisition of two suitable interferograms is sufficient for the purpose. As an important application of our technique, we demonstrate measurements of the angular Schmidt spectrum of the entangled photons produced by parametric down-conversion and report a broad spect...
Frontiers in Optics 2013, 2013
We present a novel method for efficient sorting of photons prepared in states of orbital angular momentum (OAM) and angular position (ANG). A log-polar optical transform is used in combination with a holographic beam-splitting method to achieve better mode discrimination and reduced cross-talk than reported previously. Simulating this method for 7 modes, we have calculated an improved mutual information of 2.43 bits/photon and 2.29 bits/photon for OAM and ANG modes respectively. In addition, we present preliminary results from an experimental implementation of this technique. This method is expected to have important applications for high-dimensional quantum key distribution systems.
Measuring the Orbital Angular Momentum of a Single Photon
Physical Review Letters, 2002
Measuring the Orbital Angular Momentum of a Single Photon. Jonathan Leach 1 , Miles J. Padgett 1 , Stephen M. Barnett 2 , Sonja Franke-Arnold 2 , and Johannes Courtial 1 * 1 Department of Physics and Astronomy, University ...
Measuring the Orbital Angular Momentum State of Light by Coordinate Transformation
IEEE Photonics Technology Letters, 2017
We present a method to measure the orbital angular momentum (OAM) state of light by coordinate transformation. The input OAM mode with annular shape is uniaxially compressed into a linear-shaped light, so that the upper and lower portions of OAM mode overlap to produce an interference pattern, showing easily recognizable fringes both in the near field and far field. The far-field measurement is more suitable for detecting large OAM but with the cost of additional diffractive element. The incident light can illuminate any position of the device, showing good tolerance to adjust the optical path. In a practical application, the proposed scheme can be realized only by one or two elliptical lenses, which provides a convenient and economic method for measurement of OAM state.
Photon orbital angular momentum: problems and perspectives
Fortschritte der Physik, 2004
The availability of laser beams carrying orbital angular momentum in addition to spin angular momentum paved the way to the observation of novel effects in quantum and classical optics. These effects are reviewed in this paper with emphasis on future perspectives.
Efficient measurement of an optical orbital-angular-momentum spectrum comprising more than 50 states
New Journal of Physics, 2013
A light beam may be separated into its orbital-angular momentum (OAM) components by a geometric optical transformation that converts each OAM component into a plane wave with a transverse phase gradient. Subsequent focusing produces a spot the lateral position of which is proportional to the input OAM state (Lavery et al 2012 Opt. Express 20 3). In this paper, we improve this approach, extending the measurement bandwidth to >50 OAM states and showing a simultaneous measurement of the radial coordinate.
High-efficiency measurement of all orbital angular momentum modes in a light beam
Journal of the Optical Society of America B, 2017
We present an experimental demonstration of a Laguerre-Gauss (LG) spectrum measurement technique using variable focus lenses that is able to measure the strengths of all modes present in an unknown, incoming light beam with the highest possible efficiency. The experiment modifies the classical projective, phase flattening technique by including a variable sized pinhole and a two electronic lens variable imaging system that is tuned for each mode to give the highest possible detection efficiency irrespective of the beam waist of LG mode chosen for the projection/decomposition. The modified experiment preserves the orthogonality between the modes with only a 4 % cross-talk so that superposition states may also be detected efficiently. Our experiment results show efficient detection of OAM vortex beams with topological charge, l, values ranging from 0 to 4 with various different beam waists chosen for the decomposition.