Laguerre-Gaussian supercontinuum

Author(s): H. I. Sztul, V. Kartazayev, and R. R. Alfano

Abstract:

“We show what is believed to be the first coherent white-light optical vortices generated from supercontinuum that have the azimuthally varying phase structure consistent with a monochromatic Laguerre-Gaussian beam. Two methods of Laguerre-Gaussian supercontinuum generation are discussed and contrasted. We use a computer-generated hologram to convert a Gaussian white-light supercontinuum source into Laguerre-Gaussian supercontinuum.”

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Publication: Optics Letters
Issue/Year: Optics Letters, Vol. 31, Issue 18, pp. 2725-2727, 2006
DOI: 10.1364/OL.31.002725

Generation of achromatic Bessel beams using a compensated spatial light modulator

Author(s): Jonathan Leach, Graham M. Gibson, Miles J. Padgett, Elric Esposito, Gail McConnell, Amanda J. Wright, and John M. Girkin

Abstract:

“We report the creation of white-light, achromatic Bessel beams using a spatial light modulator and a prism to compensate for the dispersion. Unlike the Bessel beam created by a refractive axicon, this achromatic beam has a radial wavevector and hence an intensity cross-section which is independent of wavelength. The technique also lends itself to the generation of higher order Bessel beams with an on-axis optical vortex and associated orbital angular momentum.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 14, Issue 12, pp. 5581-5587, 2006
DOI: 10.1364/OE.14.005581

Highly efficient phase-conjugation of a 1 µm pico-second Laguerre-Gaussian beam

Author(s): Gyeong Bok Jung, Keiichiro Kanaya, and Takashige Omatsu

Abstract:

“We have demonstrated highly efficient Laguerre Gaussian beam generation by using a ring self-pumped phase conjugate mirror in the pico-second regime for the first time. The phase conjugate reflectivity was typically ~55%. We have also investigated the conservation of optical angular momentum.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 14, Issue 6, pp. 2250-2255, 2006
DOI: 10.1364/OE.14.002250

Residue orbital angular momentum in interferenced double vortex beams with unequal topological charges

Author(s): S. H. Tao, X.-C. Yuan, J. Lin, and R. E. Burge

Abstract:

“When two vortex beams with unequal topological charges superpose coherently, orbital angular momentum (OAM) in the two beams would not be cancelled out completely in the interference. The residual OAMs contained by the superposed beam are located at different concentric rings and may have opposite orientations owing to the difference of the charges. The residual OAM can be confirmed by the rotation of microparticles when difference between the charges of two interfering beams is large.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 14, Issue 2, pp. 535-541, 2006
DOI: 10.1364/OPEX.14.000535

Fractional optical vortex beam induced rotation of particles

Author(s): S. Tao, X-C. Yuan, J. Lin, X. Peng, and H. Niu

Abstract:

“We experimentally demonstrate optical rotation and manipulation of microscopic particles by use of optical vortex beams with fractional topological charges, namely fractional optical vortex beams, which are coupled in an optical tweezers system. Like the vortex beams with integer topological charges, the fractional optical vortex beams are also capable of rotating particles induced by the transfer of orbital angular momentum. However, the unique radial opening (low-intensity gap) in the intensity ring encompassing the dark core, due to the fractional nature of the beam, hinders the rotation significantly. The fractional vortex beams orbital angular momentum and radial opening are exploited to guide and transport microscopic particles.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 13, Issue 20, pp. 7726-7731, 2005
DOI: 10.1364/OPEX.13.007726

Structure and scaling of helical modes of light

Author(s): Steven Sundbeck, Ilya Gruzberg, and David G. Grier

Abstract:

“Modes of light that contain topological defects such as screw dislocations can be focused into optical traps with interesting and useful properties. The way in which the intensity distribution within helical modes of light varies with topological charge is discussed, and new scaling predictions for their radial profiles that are consistent with experimental observations are introduced.”

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Publication: Optics Letters
Issue/Year: Optics Letters, Vol. 30, Issue 5, pp. 477-479 , 2005
DOI: 10.1364/OL.30.000477

Vortex knots in light

Author(s): J. Leach, M. R. Dennis, J. Courtial and M. J. Padgett

Abstract:

“Optical vortices generically arise when optical beams are combined. Recently, we reported how several laser beams containing optical vortices could be combined to form optical vortex loops, links and knots embedded in a light beam (Leach et al 2004 Nature 432 165). Here, we describe in detail the experiments in which vortex loops form these structures. The experimental construction follows a theoretical model originally proposed by Berry and Dennis, and the beams are synthesized using a programmable spatial light modulator and imaged using a CCD camera.”

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Publication:New Journal of Physics
Issue/Year:New J. Phys. 7, 55 (2005)
DOI: 10.1088/1367-2630/7/1/055

Laser beams: Knotted threads of darkness

Author(s): Jonathan Leach, Mark R. Dennis, Johannes Courtial & Miles J. Padgett

Abstract:

“Destructive interference may lead to complete cancellation when light waves travelling in different directions cross, and in three-dimensional space this occurs along lines that are vortices of electromagnetic energy flow. Here we confirm theoretical predictions by experimentally creating combinations of optical laser beams in which these dark threads form stable loops that are linked and knotted.”

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Publication: Nature
Issue/Year:Nature 432, 165 (11 November 2004)
DOI: 10.1038/432165a

Observation of the vortex structure of a non-integer vortex beam

Author(s): Jonathan Leach, Eric Yao and Miles J Padgett

Abstract:

“An optical beam with an eilΦ phase structure carries an orbital angular momentum of lħ per photon. For integer l values, the phase fronts of such beams form perfect helices with a single screw-phase dislocation, or vortex, on the beam axis. For non-integer l values, Berry (2004 J. Opt. A: Pure Appl. Opt. 6 259) predicts a complex-phase structure comprising many vortices at differing positions within the beam cross-section. Using a spatial light modulator we produce eilΦ beams with varying l. We examine the phase structure of such beams after propagation through an interference-based phase-measurement technique. As predicted, we observe that for half-integer l values, a line of alternating charge vortices is formed near the radial dislocation. ”

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Publication:New Journal of Physics
Issue/Year: New J. Phys. 6 (2004) 71,
DOI: 10.1088/1367-2630/6/1/071
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