Layered Tapered-Rib Waveguide for Compact Low-Loss Optical Coupling
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Solution Overview
Problem
Conventional optical devices face issues with increased optical loss and reflection due to side wall roughening in Si waveguides, and an enlarged size due to multi-stage connections in adiabatic and higher-order transformations.
Innovation Solution
The optical device employs a substrate with a tapered waveguide in a first layer and a rib waveguide in a second layer, where the rib waveguide has a core width that gradually increases, and slabs with increasing slab widths, reducing side wall roughening and enabling efficient higher-order transformations while minimizing device size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multi-stage connections are used for adiabatic and higher-order transformations, then transformation functionality is improved, but device size is enlarged
Solution Approach 1:
The patent combines adiabatic transformation and higher-order transformation into a single integrated waveguide structure. The waveguide simultaneously performs both transformation functions through its designed cross-sectional geometry and refractive index profile, eliminating the need for separate multi-stage connection structures and thereby reducing device size while maintaining full transformation functionality
Solution Approach 2:
The waveguide structure is designed to perform multiple functions simultaneously: it provides adiabatic transformation for mode coupling, higher-order transformation for polarization conversion, and spatial transition between different waveguides. This multi-functional integration eliminates the need for separate dedicated structures for each function, significantly compacting the device
2Ease of manufacture
If conventional Si waveguides are used, then manufacturing is simplified, but side wall roughening increases causing optical loss and reflection
Solution Approach 1:
The patent applies different structural qualities to different regions of the waveguide. The core region maintains standard Si waveguide properties for ease of manufacture, while the side wall regions are specifically engineered with optimized profiles and surface treatments to minimize roughening. This local differentiation allows conventional manufacturing for the bulk structure while addressing optical loss at critical interfaces
Solution Approach 2:
The waveguide employs a composite structure combining Si core with cladding materials that have optimized refractive indices. This composite design allows the Si portion to be manufactured using standard processes while the composite interface is engineered to reduce side wall roughening effects and minimize optical loss and reflection through improved material pairing and interface optimization
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration reduces optical loss and reflection, and significantly decreases the size of the optical device by optimizing waveguide transitions and connections.
Implementation Method 1
The edge coupler inputs light from the optical fiber while performing mode field matching with respect to the optical fiber
Implementation Method 2
The optical device needs to have a function to perform higher-order transformation on signal light while allowing spatial transition of the signal light between different waveguides
Implementation Method 3
the PR/PBS is able to split paths in accordance with polarization of light that is input from the edge coupler
Data Source
AI summary
An optical device includes a substrate, a tapered waveguide that is arranged in a first layer on the substrate and that has a waveguide width that gradually increases from input to output, a rib waveguide that is arranged in a second layer on the substrate, where the second layer is different from the first layer, and overlaps with the tapered waveguide in a plane direction. The rib waveguide includes a rib that has a core width that gradually increases from the input to the output, and slabs that are arranged on both sides of the rib and that have slab widths that gradually increase from the input to the output.