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Exact analysis of the evanescent coupling between two indiffused optical waveguides
Applied Optics
|March 25, 2010
Summary
An exact wave analysis of directional couplers reveals coupled-mode theory is accurate for weak waveguide coupling but unreliable for strong coupling scenarios.
Area of Science:
- Optics and Photonics
- Waveguide Theory
Background:
- Directional couplers are fundamental components in integrated optics.
- Graded-index waveguides with exponential profiles are commonly used.
- Coupled-mode theory is a prevalent method for analyzing such structures.
Purpose of the Study:
- To perform an exact scalar wave analysis of a directional coupler.
- To evaluate the accuracy of coupled-mode theory for analyzing directional couplers with exponential graded-index profiles.
Main Methods:
- Exact scalar wave analysis was employed.
- The analysis focused on two identical graded-index waveguides with exponential profiles.
Main Results:
- The study provides an exact analysis of the directional coupler.
- Comparison with coupled-mode theory was performed.
- Accuracy of coupled-mode theory was assessed based on coupling strength.
Conclusions:
- Coupled-mode theory provides accurate results for weak coupling in these structures.
- Coupled-mode theory can yield significantly inaccurate results when coupling is sufficiently strong.
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