Determination of the topological charge of complex light beams by shearing interference from a wedged optical flat

Behzad Khajavi; Enrique J. Galvez

doi:10.1117/12.2291188

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22 February 2018 Determination of the topological charge of complex light beams by shearing interference from a wedged optical flat

Behzad Khajavi, Enrique J. Galvez

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Proceedings Volume 10549, Complex Light and Optical Forces XII; 105490M (2018) https://doi.org/10.1117/12.2291188
Event: SPIE OPTO, 2018, San Francisco, California, United States

Abstract

The topological charge (l) is the parameter that defines the amount of orbital angular momentum (OAM) of beams carrying optical vortices. In this article we expand on a robust experimental method to determine the topological charge that we previously developed [B. Khajavi & E. J .Galvez, Opt. Lett. 42, 1516-1519 (2017)]. This method consist of using a pair of confocal lenses and a wedged optical flat as a shearing interferometer. The interference pattern produced by a pure OAM mode directly reveals the magnitude and sign of the topological charge: two conjoined forks with |l| + 1 number of tines pointing away from (towards) one another for l > 0 (l < 0). Superpositions of two modes with the same value of |l| but with the opposite sign produce shearing interference patterns that can be used the infer the value of l and the relative weight of the component modes.

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Behzad Khajavi and Enrique J. Galvez "Determination of the topological charge of complex light beams by shearing interference from a wedged optical flat", Proc. SPIE 10549, Complex Light and Optical Forces XII, 105490M (22 February 2018); https://doi.org/10.1117/12.2291188

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