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Proceedings Paper

Putting light in a spin
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Paper Abstract

We experimentally generated superpositions of higher-order Bessel beams that possess no global orbital angular momentum (OAM), yet exhibit an angular rotation in their intensity profile as the field propagates. The digital holograms encoded on a spatial light modulator (SLM), used for generating such fields, consist of two annular rings of unequal radial wave-vectors where each ring is encoded with an azimuthal mode of equal order but opposite charge. We present experimentally measured angular rotation rates for some example superposition fields, which are shown to be in good agreement with that predicted theoretically. Introducing a second SLM and a Fourier transforming lens, we demonstrate a simple approach to perform an azimuthal decomposition of our generated optical fields. Bounding the match-filter to an annular ring, of varying radius, we are able to perform a scale-independent azimuthal decomposition of our initial field. From the measured weightings of the azimuthally decomposed modes we show reconstruction of the cross-sectional intensity profile and OAM density of our initial field.

Paper Details

Date Published: 17 October 2012
PDF: 8 pages
Proc. SPIE 8490, Laser Beam Shaping XIII, 84900A (17 October 2012); doi: 10.1117/12.970682
Show Author Affiliations
A. Dudley, CSIR National Laser Ctr. (South Africa)
R. Rop, Moi Univ. (Kenya)
Egerton Univ. (Kenya)
I. A. Litvin, CSIR National Laser Ctr. (South Africa)
C. López-Mariscal, U.S. Naval Research Lab. (United States)
F. S. Roux, CSIR National Laser Ctr. (South Africa)
A. Forbes, CSIR National Laser Ctr. (South Africa)
Univ. of KwaZulu-Natal (South Africa)
Stellenbosch Univ. (South Africa)

Published in SPIE Proceedings Vol. 8490:
Laser Beam Shaping XIII
Andrew Forbes; Todd E. Lizotte, Editor(s)

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