Directional difference of the spin angular-momentum density and spin vectors in tightly focused bichromatic optical Lissajous beams

Xinlu Zhu, Xiangyun Li, Zhen Dong, Fei Wang, Lin Liu, Andreas Norrman, Tero Setälä, Yangjian Cai, and Yahong Chen

Phys. Rev. A 109, 043503 – Published 2 April 2024

Abstract

The spin angular-momentum density vector and the so-called spin vector reflecting the polarization properties of a light field are parallel for a monochromatic light field whose polarization ellipse at a point necessarily lies in a fixed plane. In contrast, the electric field of polychromatic light may, in general, evolve in three directions such that the average intensity in all of them is nonzero for any orientation of the reference frame. Consequently, the two vectors are no longer necessarily parallel. In this work we consider tightly focused bichromatic Lissajous beams and show that the spin angular-momentum density vector and the spin vector in such three-dimensional light fields may point in markedly different directions, almost orthogonal in some cases, and thus generally provide different information on the spin of light.

Received 21 December 2023
Accepted 19 March 2024

DOI:https://doi.org/10.1103/PhysRevA.109.043503

Physics Subject Headings (PhySH)

Angular momentum of light Optical coherence Polarization of light

Atomic, Molecular & Optical

Authors & Affiliations

Xinlu Zhu¹, Xiangyun Li¹, Zhen Dong^1,2, Fei Wang¹, Lin Liu¹, Andreas Norrman ², Tero Setälä^2,3,*, Yangjian Cai^3,4,†, and Yahong Chen ^1,‡

¹School of Physical Science and Technology, Soochow University, Suzhou 215006, China
²Center for Photonics Sciences, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland
³Shandong Provincial Engineering and Technical Center of Light Manipulation and Shandong Provincial Key Laboratory of Optics and Photonic Devices, School of Physics and Electronics, Shandong Normal University, Jinan 250014, China
⁴Joint Research Center of Light Manipulation Science and Photonic Integrated Chip of East China Normal University and Shandong Normal University, East China Normal University, Shanghai 200241, China

^*tero.setala@uef.fi
^†yangjian_cai@163.com
^‡yahongchen@suda.edu.cn

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Vol. 109, Iss. 4 — April 2024

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