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Coupling between multimode fibers and slab waveguides.
Optics Express
|November 25, 2018
Summary
This study designs a grating for efficient multimode waveguide coupling, essential for optical systems. The research addresses challenges in coupling light between multimode fibers and waveguides, improving integrated optics.
Area of Science:
- Optics
- Materials Science
- Electrical Engineering
Background:
- Grating-based coupling is established for single-mode waveguides and fibers.
- Multimode waveguide coupling is complex and less understood, yet crucial for incoherent light.
- Applications include exciting guided modes from incoherent sources and extracting radiation.
Purpose of the Study:
- To design a grating for coupling multiple modes between a 2D slab waveguide and a multimode fiber.
- To identify and discuss challenges in multimode coupling.
- To demonstrate a rudimentary design for multimode fiber-to-waveguide-to-fiber coupling.
Main Methods:
- Design of a grating coupler for multimode waveguides.
- Modeling and simulation of the coupler's performance.
- Experimental validation of the modeled geometry.
Main Results:
- A rudimentary design demonstrated coupling from a multimode fiber into a waveguide slab and back into another fiber.
- Achieved a total efficiency of -34 dB for the fiber-waveguide-fiber system.
- Good agreement between modeling and experimental results explained the coupler's physics.
Conclusions:
- Multimode waveguide coupling requires careful matching of mode numbers and scattering angles.
- Coupling efficiency can significantly decrease due to these factors.
- The study provides insights for improving directivity and maximizing coupling efficiency in future designs.
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