On electromagnetics of time-modulated structures

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School of Electrical Engineering | Doctoral thesis (article-based) | Defence date: 2022-01-21
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Authors

Date

2021

Department

Elektroniikan ja nanotekniikan laitos
Department of Electronics and Nanoengineering

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Mcode

Degree programme

Language

en

Pages

102 + app. 70

Series

Aalto University publication series DOCTORAL DISSERTATIONS, 183/2021

Abstract

Time modulation means temporal variation of properties of a structure, imposed by some external force. Depending on the spatial dimensions it can be considered as modulation of single meta-atoms or of the effective medium parameters. Time modulation of material properties brings novel ways to control electromagnetic radiation, since the modulation function can be tuned in many different ways, such as the modulation speed, amplitude, pulse shape, and more. This dissertation considers structures that have different spatial dimensions and various temporal modulations. We start from fundamental differences between static and time-varying systems and discuss the validity of the instantaneous response assumption. The first part of the dissertation focuses on phenomena that can be studied under this assumption. We show how arbitrarily modulated reactive circuit elements can mimic non-Foster behavior or cancel reflections from a load. For arbitrarily modulated meta-atoms we introduce the instantaneous power balance equation that can be used to engineer the radiated fields. For periodically modulated structures we apply the Floquet theorem to explain the properties of time-modulated capacitors in electric circuits and in capacitive metasurfaces. The second part of the dissertation deals with dipole polarizability of a single meta-atom and a transition towards time-modulated media with dispersion. We carefully derive general equations that in principle can be used for solving scattering problems in any geometry.

Description

Defence is held on 21.1.2022 16:00 – 19:00 https://aalto.zoom.us/j/8641010068

Supervising professor

Tretyakov, Sergei, Prof., Aalto University, Department of Electronics and Nanoengineering, Finland

Thesis advisor

Mirmoosa, Mohammad Sajjad, Dr., Aalto University, Finland

Keywords

time-modulation, time-varying circuits, instantaneous radiation, elementary dipoles, meta-atoms, time-varying medium, frequency dispersion, nonreciprocity, time-varying metasurface

Other note

Parts

  • [Publication 1]: M. Mirmoosa, G. Ptitcyn, V. S. Asadchy, and S. A. Tretyakov, “Time-Varying Reactive Elements for Extreme Accumulation of Electromagnetic Energy,” Physical Review Applied, vol. 11, no. 1, p. 014024, January 2019.
    Full text in Acris/Aaltodoc: http://urn.fi/URN:NBN:fi:aalto-201902251901
    DOI: 10.1103/PhysRevApplied.11.014024 View at publisher
  • [Publication 2]: G. Ptitcyn, M. S. Mirmoosa, and S. A. Tretyakov, “Time-modulated meta-atoms,” Physical Review Research, vol. 1, no. 2, p. 023014, September 2019.
    Full text in Acris/Aaltodoc: http://urn.fi/URN:NBN:fi:aalto-201911076084
    DOI: 10.1103/PhysRevResearch.1.023014 View at publisher
  • [Publication 3]: M. S. Mirmoosa, G. Ptitcyn, R. Fleury, and S. A. Tretyakov, “Instantaneous radiation from time-varying electric and magnetic dipoles,” Physical Review A, vol. 102, no. 1, p. 013503, July 2020.
    Full text in Acris/Aaltodoc: http://urn.fi/URN:NBN:fi:aalto-202008214798
    DOI: 10.1103/PhysRevA.102.013503 View at publisher
  • [Publication 4]: X. Wang, G. Ptitcyn, V. Asadchy, A. Díaz-Rubio, M. Mirmoosa, S. Fan, and S. A. Tretyakov, “Nonreciprocity in Bianisotropic Systems with Uniform Time Modulation,” Physical Review Letters, vol. 125, no. 26, p. 266102, December 2020.
    Full text in Acris/Aaltodoc: http://urn.fi/URN:NBN:fi:aalto-202101271659
    DOI: 10.1103/PhysRevLett.125.266102 View at publisher
  • [Publication 5]: M. S. Mirmoosa, T. T. Koutserimpas, G. Ptitcyn, S. A. Tretyakov, and R. Fleury, “Dipole polarizability of time-varying particles,” Submitted to Physical Review Research, arXiv:2002.12297v2, February 2020
  • [Publication 6]: G. Ptitcyn, A. Lamprianidis, T. Karamanos, M. Müller, R. Alaee, V. S. Asadchy, M. S. Mirmoosa, M. Albooyeh, S. Fan, C. Rockstuhl, and S. A. Tretyakov, “Scattering of light by spheres made from a time-modulated and dispersive material,” 2021 Fifteenth International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials), pp. 347-349, October 2021.
    Full text in Acris/Aaltodoc: http://urn.fi/URN:NBN:fi:aalto-2021112410337
    DOI: 10.1109/Metamaterials52332.2021.9577064 View at publisher

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https://urn.fi/URN:ISBN:978-952-64-0645-9

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