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Prediction of coupling length in a rectangular-core directional coupler: an accurate analysis
Optics Letters
|September 3, 2009
Summary
Marcatili
Area of Science:
- Optics and Photonics
- Integrated Photonics
- Waveguide Theory
Background:
- Directional couplers are fundamental components in integrated photonics.
- Marcatili's analysis is a widely used method for calculating coupling length in rectangular-core directional couplers.
- Existing analyses may not fully account for corner region effects.
Purpose of the Study:
- To evaluate the accuracy of Marcatili's analysis for rectangular-core directional couplers.
- To investigate the impact of corner regions on coupling length predictions.
- To identify conditions where Marcatili's analysis may be inaccurate for practical single-mode channel waveguides.
Main Methods:
- Comparison of Marcatili's analysis with a simple slab-waveguide approximation.
- Application of first-order perturbation theory to incorporate corner region effects.
- Analysis of rectangular-core directional couplers with varying channel waveguide depths.
Main Results:
- Marcatili's analysis closely matches the slab-waveguide approximation for coupling length.
- A more accurate analysis reveals discrepancies when corner regions are considered.
- Inaccuracies arise in Marcatili's predictions for small channel waveguide depths.
Conclusions:
- Marcatili's analysis may yield inaccurate coupling length values for practical single-mode channel waveguides with small depths.
- First-order perturbation theory provides a more accurate approach by including corner effects.
- Refined analysis is crucial for the precise design of directional couplers in integrated photonic circuits.
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