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Microwave Photonics Systems Based on Whispering-gallery-mode Resonators
Published on: August 5, 2013
Oscillatory vertical coupling between a whispering-gallery resonator and a bus waveguide.
M Ghulinyan1, F Ramiro-Manzano, N Prtljaga
1Advanced Photonics and Photovoltaics Unit, Fondazione Bruno Kessler, I-38123 Povo, Italy. ghulinyan@fbk.eu
Physical Review Letters
|May 18, 2013
Summary
We explored vertical optical coupling between a whispering-gallery resonator and a waveguide. The study reveals oscillatory coupling behavior with vertical gap changes, impacting transmission and quality factor.
Area of Science:
- Photonics and Optical Engineering
- Nanophotonics
- Integrated Optics
Background:
- Whispering-gallery resonators offer high-quality optical confinement.
- Waveguide-resonator coupling is crucial for integrated photonic devices.
- In-plane coupling is standard, but vertical coupling presents unique challenges and opportunities.
Purpose of the Study:
- To theoretically and experimentally investigate optical coupling between a whispering-gallery resonator and a waveguide in a vertical configuration.
- To analyze the impact of vertical separation on coupling efficiency and resonator performance.
- To develop an analytical model for vertical waveguide-resonator coupling.
Main Methods:
- Theoretical modeling using coupled-mode theory.
- Development of a two-port beam-splitter model for vertical coupling.
- Experimental fabrication and characterization of the vertical coupling system.
- Analysis of resonance peak waveguide transmission and mode quality factor.
Main Results:
- Observed oscillatory behavior of effective coupling as a function of the vertical gap.
- Demonstrated oscillations in resonance peak waveguide transmission.
- Showcased oscillations in the mode quality factor of the resonator.
- Validated the analytical model against experimental data for arbitrary phase-matching conditions.
Conclusions:
- Vertical coupling between whispering-gallery resonators and waveguides exhibits unique oscillatory characteristics.
- The developed analytical model accurately describes and predicts the observed coupling phenomena.
- This study provides insights for designing novel integrated photonic devices with enhanced control over optical coupling.
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