Diffraction of hollow beams by dielectric microparticles and microsphere assisted microscopy

Thumbnail Image

Files

isbn9789526411972.pdf (24.1 MB)

URL

Journal Title

Journal ISSN

Volume Title

School of Electrical Engineering | Doctoral thesis (article-based) | Defence date: 2023-10-27
Unless otherwise stated, all rights belong to the author. You may download, display and print this publication for Your own personal use. Commercial use is prohibited.

Authors

Date

2023

Department

Elektroniikan ja nanotekniikan laitos
Department of Electronics and Nanoengineering

Major/Subject

Mcode

Degree programme

Language

en

Pages

90 + app. 71

Series

Aalto University publication series DOCTORAL THESES, 40/2023

Abstract

One of the main tasks of nano-optics is to produce nanostructured light that has spatial features well below the wavelength of visible light. In the present work, we theoretically reveal and study the nanostructured light resulting from the diffraction by a dielectric sphere or cylinder. The peculiarity of our nanostructured light is its location in free space at a substantial distance from the particle. We analyze the electromagnetic fields inside and behind a dielectric sphere's rear edge, illuminated by a hollow Bessel wave beam. We theoretically reveal a new kind of resonance called the spatial Fano resonance. The main minimum of the electromagnetic field is strongly subwavelength and noticeably distanced from the sphere's rear edge. A similar result we also obtained for the incidence of a 2D hollow wave beam called the cosine beam onto the microcylinder. We prove that this resonance can be utilized for a submicron optical trap. We also found the regime of subwavelength field concentration outside the microparticle, which could have applications such as cavity-enhanced fluorescence and cavity-enhanced all-dielectric Raman scattering. Results of this study are presented in the first part of this thesis. The second part of this thesis corresponds to the excitation of a dielectric microsphere or a microcylinder by point-wise dipoles. Capability of a simple dielectric sphere to offer label-free, far-field real-time subwavelength imaging of planar objects was experimentally revealed a decade ago. However, since then, the scientific community has yet to find a suitable explanation for this effect for a non-resonant microparticle. We have suggested a non-resonant mechanism for this superresolution and estimated the bounds of the ultimate resolution for the 2D case (imaging microcylinder). Our imaging mechanism does not involve evanescent waves. Instead, we exploit the property of a dipole scatterer that does not radiate along its direction.

Description

Supervising professor

Simovski, Constantin, Prof., Aalto University, Department of Electronics and Nanoengineering, Finland

Keywords

dielectric microsphere, nano-optics, microsphere

Other note

Parts

  • [Publication 1]: V. Klimov, R. Heydarian, C. Simovski. Dielectric microcylinder makes a nanocylindrical trap for atoms and ions. Physical Review B, Vol. 103, no. 16, p. 165405, Apr. 2021.
    Full text in Acris/Aaltodoc: http://urn.fi/URN:NBN:fi:aalto-202204062737
    DOI: 10.1103/PhysRevB.103.165405 View at publisher
  • [Publication 2]: R. Heydarian, V. Klimov, C. Simovski. Subwavelength effects near a dielectric microcylinder illuminated by a diffraction-free beam. Photonics and Nanostructures - Fundamentals and Applications, Vol. 43, p. 100894, Feb. 2021.
    Full text in Acris/Aaltodoc: http://urn.fi/URN:NBN:fi:aalto-202101251513
    DOI: 10.1016/j.photonics.2021.100894 View at publisher
  • [Publication 3]: V. Klimov, R. Heydarian, C. Simovski. Spatial Fano resonance of a dielectric microsphere impinged on by a Bessel beam. Journal of the Optical Society of America B, Vol. 38, no. 9, p. c84, Jul. 2021.
    DOI: 10.1364/JOSAB.424927 View at publisher
  • [Publication 4]: R. Heydarian, C. Simovski. Non-resonant subwavelength imaging by dielectric microparticles. Photonics and Nanostructures - Fundamentals and Applications, Vol. 46, p. 100950, Sep. 2021.
    DOI: 10.1016/j.photonics.2021.100950 View at publisher
  • [Publication 5]: R. Heydarian, C. Simovski. Inverse propagation method for evaluation of superresolution granted by dielectric microparticles. Journal of the Optical Society of America A, Vol. 39, no. 7, p. 1256–1266, Jul. 2022.
    Full text in Acris/Aaltodoc: http://urn.fi/URN:NBN:fi:aalto-202301181318
    DOI: 10.1364/JOSAA.457587 View at publisher
  • [Publication 6]: R. Heydarian, C. Simovski. Cross polarization of nano-objects located on a flat substrate in the presence of a glass microparticle. Journal of the Optical Society of America A, Vol. 39, no. 12, p. 2124–2130, Dec. 2022.
    Full text in Acris/Aaltodoc: http://urn.fi/URN:NBN:fi:aalto-202301181152
    DOI: 10.1364/JOSAA.471428 View at publisher

Citation

Permanent link to this item

https://urn.fi/URN:ISBN:978-952-64-1197-2

Collections

[diss] Sähkötekniikan korkeakoulu / ELEC