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Published on: November 30, 2012
Modified Maxwell fish-eye approach for efficient coupler design by graded photonic crystals
1Nanophotonics Research Laboratory Department of Electrical and Electronics Engineering TOBB University of Economics and Technology, Ankara 06560, Turkey.
Optics Express
|October 6, 2012
Summary
We developed a novel graded index (GRIN) medium using photonic crystals to efficiently couple light between dielectric waveguides of different widths. This GRIN photonic crystal coupler achieves high coupling efficiency and is robust against misalignment.
Area of Science:
- Photonics
- Optoelectronics
- Materials Science
Background:
- Traditional butt-couplers suffer from low light coupling efficiency between waveguides of differing widths.
- Tapered couplers improve efficiency but require extended device lengths.
- Reducing coupling losses is crucial for integrated optical devices.
Purpose of the Study:
- To design a novel two-dimensional graded index (GRIN) medium for efficient light coupling.
- To achieve high coupling efficiency between planar dielectric waveguides with significantly different widths (15.46 μm vs. 2.21 μm).
- To investigate the robustness of the proposed coupler against misalignment.
Main Methods:
- A novel GRIN medium design based on a modified Maxwell fish-eye lens concept.
- Approximation of the inhomogeneous refractive index distribution using photonic crystals (PCs).
- Strategic arrangement of PC rods to achieve desired refractive index profiles.
Main Results:
- High coupling efficiency of approximately 90% was achieved.
- A spectral bandwidth of 18.56% (284 nm) for coupling efficiency over 75%.
- Demonstrated robustness against lateral displacement and angular misalignment of output waveguides.
Conclusions:
- The proposed GRIN photonic crystal coupler offers a significant improvement over conventional methods.
- The design enables efficient light transfer between waveguides of varying dimensions.
- The coupler exhibits practical resilience, making it suitable for real-world applications.
