Spot-Size Converter Gradient Waveguide Coupling
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Solution Overview
Problem
The coupling efficiency between integrated optical waveguides and optical fibers is low due to the significant difference in spot size, leading to high light energy loss and potential heating issues at the coupling end face.
Innovation Solution
A spot-size converter structure is designed with a substrate, an isolation layer, a waveguide layer, and a covering layer, where the waveguide layer's width decreases in a gradient manner approaching the optical fiber end face, and the covering layer has a second transmission portion extending to the fiber end face, facilitating better light coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If edge coupling is used to couple integrated optical waveguide to optical fiber, then the coupling structure is simple, but the coupling efficiency is low due to spot size mismatch
Solution Approach 1:
The patent introduces a spot-size converter as an intermediary device between the integrated optical waveguide and optical fiber. This converter includes a waveguide layer with gradient width that progressively transforms the spot size from the waveguide to match the fiber diameter, thereby improving coupling efficiency without significantly increasing overall system complexity
Solution Approach 2:
The waveguide layer's width is designed to decrease in a gradient manner from the waveguide end toward the fiber end. This continuous parameter change (width reduction) enables smooth spot size transformation, allowing the light mode to adapt progressively from the waveguide confinement to the fiber acceptance mode, thus reducing optical loss
2Loss of energy
If spot size converter is added to improve coupling efficiency, then light energy loss is reduced, but device complexity increases
Solution Approach 1:
The spot-size converter is integrated directly with the optical waveguide and fiber coupling structure. The waveguide layer, isolation layer, and covering layer form a unified component that combines waveguide functionality with spot size transformation, eliminating the need for separate discrete components and reducing overall device complexity
3Loss of energy
If gradient width waveguide layer is used, then coupling efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The waveguide layer is designed with different width characteristics in different regions: wider near the waveguide input and progressively narrower toward the fiber end. This local variation in geometry is implemented through standard semiconductor fabrication processes (etching, deposition) that can achieve the required gradient profile with conventional precision, balancing performance with manufacturability
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
The proposed spot-size converter structure enhances the coupling efficiency between integrated optical waveguides and optical fibers, reducing optical loss and improving the reliability and service life of photonic devices.
Implementation Method 1
An optical waveguide is a dielectric apparatus that guides the propagation of light waves therein
Implementation Method 2
the width of the waveguide layer decreasing in a gradient manner in a direction approaching the second end face
Data Source
AI summary
Provided are a spot-size converter structure and a photonic device. The spot-size converter structure comprises: a first end face configured to be coupled to an integrated optical waveguide, and a second end face parallel to the first end face configured to be coupled to an optical fiber and. The spot-size converter structure comprises: a substrate; an isolation layer located on one side of the substrate; a waveguide layer located on one side of the isolation layer away from the substrate; and a covering layer located on one side of the waveguide layer away from the substrate and covering the waveguide layer.