6–10 Jul 2026
University of the Western Cape
Africa/Johannesburg timezone
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Fractional optical skyrmions

7 Jul 2026, 11:00
20m
Lecture Hall DL1 (University of the Western Cape)

Lecture Hall DL1

University of the Western Cape

Oral Presentation Track C - Photonics Photonics

Speaker

Dr Ram Nandan Kumar (University of the Witwatersrand)

Description

Optical topologies in the form of Skyrmions have predominantly been generated using integer orbital angular momentum (OAM) modes, resulting in integer-valued topological numbers that remain invariant and robust during propagation through complex media. Here, we demonstrate the first realization of fractional Skyrmions by structuring light as a vectorial superposition of non-integer OAM modes. We show that the fractional skyrmion number evolves nonlinearly between adjacent integer values. This nonlinearity arises from the intrinsic phase discontinuity of fractional OAM modes and effectively bridges discrete topological orders. Our experimental results are in good agreement with simulations, opening a new regime of optical topologies with potential applications in optical communication and sensing.

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Author

Dr Ram Nandan Kumar (University of the Witwatersrand)

Co-authors

Mr Yuancong Cao (School of Physics, Xidian University, Xi'an, China) Mr Hadrian Bezuidenhout (University of the Witwatersrand) Prof. Mingjian Cheng (School of Physics, Xidian University, Xi'an, China) Mr Lixin Guo (School of Physics, Xidian University, Xi'an, China) ANDREW FORBES (U. Witwatersrand)

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