Azimuthal decomposition with digital holograms

Litvin, Igor A.; Dudley, Angela; Roux, Filippus S.; Forbes, Andrew

doi:10.1364/oe.20.010996

Cited by 81 publications

(54 citation statements)

References 17 publications

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“…We have demonstrated a modal decomposition technique for the extraction of the OAM spectrum of an optical field which requires only an SLM and a lens [28][29][30]. For a superposition of two Bessel beams of azimuthal indices l = +3 and -3, we find that while the global OAM is zero, the local OAM spectrum changes radially across the beam.…”

Section: Resultsmentioning

confidence: 99%

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Techniques to sort Bessel beams

et al. 2013

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In this work we will present two techniques for the measurement of superimposed higher-order Bessel beams. In the first technique we will outline a simple approach using only a spatial light modulator and a Fourier transforming lens to decompose the OAM spectrum of an optical field. We test this approach on symmetric and non-symmetric superpositions of non-diffracting higher-order Bessel beams. Our second procedure consists of two refractive optical elements which perform a Cartesian to log-polar coordinate transformation, translating helically phased beams into a transverse phase gradient. By introducing two cylindrical lenses we can focus each of the azimuthal modes associated with each Bessel beam to a different lateral position in the Fourier plane, while separating the radial wave-vectors in the image-plane.

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Section: Resultsmentioning

confidence: 99%

“…The first technique involves a spatial light modulator and a Fourier transforming lens to decompose the OAM spectrum of an optical field [28][29][30]. We implement this technique on symmetric and non-symmetric superpositions of non-diffracting higher-order Bessel beams.…”

Section: Introductionmentioning

confidence: 99%

Techniques to sort Bessel beams

et al. 2013

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“…[22][23][24][25][26][27][28] Regarding the measurement of the spatially resolved OAM density, only a single approach based on azimuthal decomposition is currently known. 29,30 Even though this technique has the advantage of being independent of the scale of the beam, it necessitates to scan the beam in radial direction, which makes this approach time-consuming.…”

Section: Introductionmentioning

confidence: 99%

Modal decomposition for measuring the orbital angular momentum density of light

Schulze

Flamm

Dudley

et al. 2013

Complex Light and Optical Forces VII

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We present a novel technique to measure the orbital angular momentum (OAM) density of light. The technique is based on modal decomposition, enabling the complete reconstruction of optical fields, including the reconstruction of the beam's Poynting vector and the OAM density distribution. The modal decomposition is performed using a computer-generated hologram (CGH), which allows fast and accurate measurement of the mode spectrum. The CGH encodes the modes of interest, whose powers and relative phase differences are measured from the far-field diffraction pattern of the incident optical field with the hologram transmission function. In combination with a classical measurement of Stokes parameters, including a polarizer and a quarter-wave plate in front of the hologram, the polarization state of each mode is measured. As a consequence, any arbitrary vector field can be reconstructed, including amplitude, phase, and polarization. Having all information on the optical field, the Poynting vector and the OAM density can be calculated directly. We applied our method to beams emerging from optical fibers and free space beams, which allows us to investigate arbitrary coherent mode superpositions with complexly shaped intensity and polarization distributions. As a reference distinct beams of known OAM density were created using a spatial light modulator (SLM). Comparisons of measured and expected results reveal very good agreement.

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“…A modified Mach-Zehnder interferometer can also be described to determine both the angular and radial mode content of scalar optical fields [24] but such systems are known to be sensitive to alignment [24]. Digital holograms are also used to extract the azimuthal modal content of optical fields for the reconstruction of its amplitude, phase and OAM density [25]. Recently it has been demonstrated that two spatial light modulators in conjunction with a lens can be used to convert the OAM state of light to a specified lateral position [26][27][28] so that the azimuthal information may be extracted, while leaving the radial component undefined.…”

Section: Introductionmentioning

confidence: 99%

Efficient sorting of Bessel beams

Mhlanga

Dudley

McDonald

et al. 2013

Complex Light and Optical Forces VII

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Abstract:We demonstrate the efficient sorter of Bessel beams separating both the azimuthal and radial components. This is based upon the recently reported transformation of angular to transverse momentum states. We separately identify over forty azimuthal and radial components, with a radial spacing of 1588 m −1 , and outline how the device could be used to identify the two spatial dimensions simultaneously.

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Azimuthal decomposition with digital holograms

Cited by 81 publications

References 17 publications

Techniques to sort Bessel beams

Techniques to sort Bessel beams

Modal decomposition for measuring the orbital angular momentum density of light

Efficient sorting of Bessel beams

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