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Spin Hall Effect of Double-Index Cylindrical Vector Beams in a Tight Focus
Alexey A Kovalev1,2, Victor V Kotlyar1,2
1Image Processing Systems Institute of the RAS-Branch of FSRC "Crystallography & Photonics" of the RAS, 151 Molodogvardeyskaya St., 443001 Samara, Russia.
Micromachines
|February 25, 2023
Summary
We found that specific light beam properties can create alternating positive and negative spin angular momentum (SAM) in tight focus. This discovery has applications in designing micro-machines with optically driven elements.
Area of Science:
- Optics and Photonics
- Light-Matter Interactions
Background:
- Cylindrical vector beams (CVBs) are crucial in optical manipulation.
- Generalizing CVBs allows for novel polarization states and focused field properties.
Purpose of the Study:
- To investigate the spin angular momentum (SAM) distribution of double-index CVBs in tight focus.
- To explore the occurrence of the spin Hall effect (SHE) in such focused beams.
- To analyze the potential for creating unique focal patterns with alternating SAM regions.
Main Methods:
- Utilizing the Richards-Wolf theory for focused electromagnetic fields.
- Analyzing the spin angular momentum (SAM) distribution based on beam properties.
- Investigating the orbital angular momentum (OAM) spectrum of the focused field components.
Main Results:
- A generalized expression for SAM distribution in tight focus was derived.
- The spin Hall effect (SHE), characterized by alternating positive and negative SAM, was observed when polarization orders have different parity.
- The OAM spectrum analysis identified dominant angular harmonics, enabling prediction of SAM distribution.
- Demonstrated the ability to generate focal patterns with alternating positive and negative SAM regions in rings or semicircles.
Conclusions:
- Double-index CVBs exhibit unique SAM distributions in tight focus, including the spin Hall effect.
- The findings enable precise control over SAM in optical foci.
- Potential applications include the design of advanced micromachines with optically driven components.
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