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Microwave Photonics Systems Based on Whispering-gallery-mode Resonators
Published on: August 5, 2013
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Mode-selective coupling between few-mode fibers and buried channel waveguides
Optics Express
|January 7, 2017
Summary
Achieving mode-selective coupling for six spatial modes in few-mode fibers and waveguides requires precise parameter matching. Optimized butt-coupling minimizes modal crosstalk and loss for mode-division multiplexing applications.
Area of Science:
- Photonics and Optical Engineering
- Waveguide and Fiber Optics
Background:
- Mode-division multiplexing (MDM) enables higher data capacity by utilizing multiple spatial modes.
- Efficiently coupling light between few-mode fibers and integrated waveguides is crucial for MDM systems.
- Minimizing modal crosstalk and loss during coupling is essential for practical device implementation.
Purpose of the Study:
- To analyze butt-coupling between few-mode fibers and buried channel waveguides.
- To identify conditions for achieving mode-selective coupling for the first six spatial modes.
- To guide the design of mode-selective waveguide devices for MDM.
Main Methods:
- Intensive computational analysis of butt-coupling scenarios.
- Investigating coupling between rectangular-core waveguides and circular-core (step-index and parabolic-index) and elliptical-core fibers.
- Evaluating modal crosstalk and butt-coupling losses for various parameter combinations.
Main Results:
- Modal crosstalk below -20 dB for six spatial modes is achievable with specific waveguide and fiber parameter matching.
- For circular-core fibers, waveguide core shape close to square (±0.7% aspect ratio variation) and matched mode volumes are key.
- Elliptical-core fibers offer flexibility in parameter matching, with parabolic-index profiles further improving selectivity and relaxing tolerances.
Conclusions:
- Optimized butt-coupling enables low-crosstalk (< -20 dB) and low-loss (< 1 dB) coupling of six spatial modes.
- Design guidelines are provided for mode-selective waveguide devices like (de)multiplexers and mode converters.
- Results support the advancement of fiber-based mode-division multiplexing technologies.
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