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A minimal subwavelength focal spot for the energy flux
S.S. Stafeev 1,2, V.D. Zaicev 1,2

1 IPSI RAS – Branch of the FSRC "Crystallography and Photonics" RAS,
443001, Samara, Russia, Molodogvardeyskaya 151,
2 Samara National Research University, Moskovskoye Shosse 34, 443086, Samara, Russia

 PDF, 855 kB

DOI: 10.18287/2412-6179-CO-908

Pages: 685-691.

Full text of article: Russian language.

Abstract:
It is shown theoretically and numerically that circularly and linearly polarized incident beams produce at the tight focus identical circularly symmetric distributions of an on-axis energy flux. It is also shown that the on-axis energy fluxes from radially and azimuthally polarized optical vortices with unit topological charge are equal to each other. An optical vortex with azimuthal polarization is found to generate the minimum focal spot measured for the intensity (all other parameters being equal). Slightly larger (by a fraction of a percent) is the spot size calculated for the energy flux for the circularly and linearly polarized light. The spot size in terms of intensity is of importance in light-matter interaction, whereas the spot size in terms of energy flux affects the resolution in optical microscopy.

Keywords:
tight focusing, Richards-Wolf formula, energy flux, radial polarization, azimuthal polarization, optical vortex.

Citation:
Stafeev SS, Zaicev VD. A minimal subwavelength focal spot for the energy flux. Computer Optics 2021; 45(5): 685-691. DOI: 10.18287/2412-6179-CO-908.

Acknowledgements:
This work was supported by the RF Ministry of Science and Higher Education within the government project of the FSRC “Crystallography and Photonics” RAS (Sections “Introduction” and “Conclusions”), the Russian Science Foundation under project No. 18-19-00595 (“Numerical simulation”), and the Russian Foundation for Basic Research under project No. 18-29-2003 (“Focusing of circularly polarized light”).

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