Phase detection of coherence singularities and determination of the topological charge of a partially coherent vortex beam

Xingyuan Lu, Chengliang Zhao, Yifeng Shao, Jun Zeng, Sander Konijnenberg, Xinlei Zhu, Sergei Popov, H. Paul Urbach, Yangjian Cai

Research output: Contribution to journalArticleScientificpeer-review

11 Citations (Scopus)
18 Downloads (Pure)

Abstract

In the theory of partial coherence, coherence singularities can occur in the spectral degree of coherence (SDOC): in case the fields at two different points are completely uncorrelated, the phase of the SDOC is undefined. For a partially coherent vortex beam, the detection of coherence singularities is linked to the measurement of topological charge, whose magnitude equals the number of ring dislocations in its far field amplitude. However, the phase distribution of coherence singularities is rarely mentioned in the literature and the amplitude distribution can hardly reflect the sign of topological charge. In this letter, we present a phase-analysis method for measuring the coherence singularities by introducing a movable perturbation at a certain point in an illumination window of a finite size. Using the proposed method, we measure experimentally the coherence singularities of a partially coherent vortex beam in the focal plane. From the results, the magnitude and sign of the topological charge can be determined simultaneously from the phase distribution of the coherence singularities. Our results can find application in information transmission.

Original languageEnglish
Article number201106
Number of pages5
JournalApplied Physics Letters
Volume114
Issue number20
DOIs
Publication statusPublished - 2019

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