Spin angular momentum at the sharp focus of a cylindrical vector vortex beam
Sharp focusing of a light field with double (phase and polarization) singularity is studied. Using the Richards-Wolf method, an exact analytical expression for the longitudinal projection of the spin angular momentum (SAM) vector at the focus is obtained. The expression derived suggests that 4 (n –1...
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| Language: | English |
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Samara National Research University
2023-12-01
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| Series: | Компьютерная оптика |
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| Online Access: | https://www.computeroptics.ru/eng/KO/Annot/KO47-6/470604e.html |
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| author | V.V. Kotlyar S.S. Stafeev A.M. Telegin |
| author_facet | V.V. Kotlyar S.S. Stafeev A.M. Telegin |
| author_sort | V.V. Kotlyar |
| collection | DOAJ |
| description | Sharp focusing of a light field with double (phase and polarization) singularity is studied. Using the Richards-Wolf method, an exact analytical expression for the longitudinal projection of the spin angular momentum (SAM) vector at the focus is obtained. The expression derived suggests that 4 (n –1) subwavelength regions are formed at the focus, where n is the cylindrical vector beam order, with their centers located on a certain circle centered on the optical axis. Notably, the SAM projections are found to have the opposite sign in the neighboring regions. This means that in the neighboring focal regions, the light has alternating left or right elliptical polarization (manifestation of a spin Hall effect). At the center of the focal spot near the optical axis, the field is right-handed elliptically polarized at m > 0, or left-handed elliptically polarized at m < 0, where m is the vortex charge. The total longitudinal spin, i.e., the longitudinal SAM component averaged over the beam-cross section, is zero and preserved upon focusing. Due to the beam containing an optical vortex with charge m, the transverse energy flow rotates on a spiral path near the focal plane, rotating on a circle in the focal plane. The rotation direction near the optical axis is counterclockwise for m > 0, and clockwise for m < 0. |
| format | Article |
| id | doaj-art-b1e3ff166a97460ebda554a2c80e6cfc |
| institution | Kabale University |
| issn | 0134-2452 2412-6179 |
| language | English |
| publishDate | 2023-12-01 |
| publisher | Samara National Research University |
| record_format | Article |
| series | Компьютерная оптика |
| spelling | doaj-art-b1e3ff166a97460ebda554a2c80e6cfc2025-01-23T09:30:54ZengSamara National Research UniversityКомпьютерная оптика0134-24522412-61792023-12-0147687588310.18287/2412-6179-CO-1347Spin angular momentum at the sharp focus of a cylindrical vector vortex beamV.V. Kotlyar0S.S. Stafeev1A.M. Telegin2IPSI RAS – Branch of the FSRC "Crystallography and Photonics" RAS; Samara National Research UniversityIPSI RAS – Branch of the FSRC "Crystallography and Photonics" RAS; Samara National Research UniversityIPSI RAS – Branch of the FSRC "Crystallography and Photonics" RAS; Samara National Research UniversitySharp focusing of a light field with double (phase and polarization) singularity is studied. Using the Richards-Wolf method, an exact analytical expression for the longitudinal projection of the spin angular momentum (SAM) vector at the focus is obtained. The expression derived suggests that 4 (n –1) subwavelength regions are formed at the focus, where n is the cylindrical vector beam order, with their centers located on a certain circle centered on the optical axis. Notably, the SAM projections are found to have the opposite sign in the neighboring regions. This means that in the neighboring focal regions, the light has alternating left or right elliptical polarization (manifestation of a spin Hall effect). At the center of the focal spot near the optical axis, the field is right-handed elliptically polarized at m > 0, or left-handed elliptically polarized at m < 0, where m is the vortex charge. The total longitudinal spin, i.e., the longitudinal SAM component averaged over the beam-cross section, is zero and preserved upon focusing. Due to the beam containing an optical vortex with charge m, the transverse energy flow rotates on a spiral path near the focal plane, rotating on a circle in the focal plane. The rotation direction near the optical axis is counterclockwise for m > 0, and clockwise for m < 0.https://www.computeroptics.ru/eng/KO/Annot/KO47-6/470604e.htmlspin angular momentumtight focusingcylindrical vector beamoptical vortex |
| spellingShingle | V.V. Kotlyar S.S. Stafeev A.M. Telegin Spin angular momentum at the sharp focus of a cylindrical vector vortex beam Компьютерная оптика spin angular momentum tight focusing cylindrical vector beam optical vortex |
| title | Spin angular momentum at the sharp focus of a cylindrical vector vortex beam |
| title_full | Spin angular momentum at the sharp focus of a cylindrical vector vortex beam |
| title_fullStr | Spin angular momentum at the sharp focus of a cylindrical vector vortex beam |
| title_full_unstemmed | Spin angular momentum at the sharp focus of a cylindrical vector vortex beam |
| title_short | Spin angular momentum at the sharp focus of a cylindrical vector vortex beam |
| title_sort | spin angular momentum at the sharp focus of a cylindrical vector vortex beam |
| topic | spin angular momentum tight focusing cylindrical vector beam optical vortex |
| url | https://www.computeroptics.ru/eng/KO/Annot/KO47-6/470604e.html |
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