Singular skeleton evolution and topological reactions in edge-diffracted circular optical-vortex beams

OPTICS COMMUNICATIONS

卷:397

Article

Bekshaev, Aleksandr¹  Chernykh, Aleksey²  Khoroshun, Anna²  Mikhaylovskaya, Lidiya¹ 

[1] Odessa II Mechnikov Natl Univ, Dvorianska 2, UA-65082 Odessa, Ukraine

[2] East Ukrainian Natl Univ, Pr Radiansky 59-A, Severodonetsk, Ukraine

关键词: Optical vortex;    Diffraction;    Laguerre-Gaussian beam;    Kummer beam;    Phase singularity;    Topological reaction;   

DOI  :  10.1016/j.optcom.2017.03.062

来源: Elsevier

【 摘 要 】

Edge diffraction of a circular optical vortex (OV) beam transforms its singular structure: a multicharged axial OV splits into a set of single-charged ones that form the 'singular skeleton' of the diffracted beam. The OV positions in the beam cross section depend on the propagation distance as well as on the edge position with respect to the incident beam axis, and the OV cores describe regular trajectories when one or both change. The trajectories are not always continuous and may be accompanied with topological reactions, including emergence of new singularities, their interaction and annihilation. Based on the Kirchhoff-Fresnel integral, we consider the singular skeleton behavior in diffracted Kummer beams and Laguerre-Gaussian beams with topological charges 2 and 3. We reveal the nature of the trajectories' discontinuities and other topological events in the singular skeleton evolution that appear to be highly sensitive to the incident beam properties and diffraction geometry. Conditions for the OV trajectory discontinuities and mechanisms of their realization are discussed. Conclusions based on the numerical calculations are supported by the asymptotic analytical model of the OV beam diffraction. The results can be useful in the OV metrology and for the OV beam's diagnostics.

【 授权许可】

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