The Impact of Non-reciprocal One-way Propagation on the Coupling between Electromagnetic Resonators and Waveguides

Zarif, Arezoo | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 49788 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Mehrany, Khashayar; Rajaei, Behzad
  7. Abstract:
  8. Subwavelength localization of electromagnetic energy with intense local fields, also known as electromagnetic hotspots, has received significant attention over the past few decades. In most cases the hotspot is achieved through the resonant concentration of electromagnetic fields. One way recently considered to get hotspot is through reflection of electromagnetic waves in nonreciprocal one-way structures, in plasmonics and via magneto optic effect.However these hotspots are less confined compared to hotspots caused by resonances. So combining nonreciprocal structures with resonance can provide better hotspots.Our aim in this thesis is to study nonreciprocal resonant structures using coupled mode theory. Conventional coupled mode theory formulation is derived phenomenologically assuming reciprocity and time-invariance, so this approach can’t be used to study nonreciprocal, time variant structures and we should derive coupled mode theory rigorously. In this thesis we first review the conventional coupled mode theory for standing wave and traveling wave resonators and consider side-coupling and shoulder- coupling configurations. Then we derive our proposed coupled mode theory formulation. Our formulation is comprehensive and can be used to solve any resonant structure. Results of the proposed formulation for standing wave and traveling wave resonators are in good agreement with conventional coupled mode theory and numerical simulation. We show that for a plasmonic resonator consists of a rectangular ring, the proposed formulation provide more accurate results than the conventional coupled mode theory. At the end we study a nonreciprocal time variant structure with broken time-reversal and space-inversion symmetry. We extend the proposed formulation to the time variant case and demonstrate nonreciprocal behavior in this structure
  9. Keywords:
  10. Coupled Mode ; Traveling Wave Resonator ; Standing Wave Resonator ; Nonreciprocal Time Variant Structures

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