Semiconductor Optical Waveguide Buried Ridge Transition
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Solution Overview
Problem
In optical integrated elements, coupling waveguides with different cross-sectional structures leads to increased optical output loss due to reflection and radiation at the coupling portion, and existing solutions fail to efficiently inject current into the core layer of buried waveguides, resulting in inefficient operation.
Innovation Solution
A semiconductor optical waveguide configuration with a core layer, cladding layer, and current blocking layer is used, where the core layer is sandwiched by the cladding layer in the layer-stacking direction and the current blocking layer in the width direction, and the waveguide structure gradually changes from a buried to a ridge shape to reduce optical loss and enhance current injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If waveguides with different cross-sectional structures are simply coupled, then device integration is achieved, but reflection and radiation occur at the coupling portion increasing optical output loss
Solution Approach 1:
The patent applies parameter changes by gradually transforming the cross-sectional structure parameters of the waveguide from a ridge shape to a buried shape (or vice versa) in the coupling region. This continuous parameter transformation matches the mode shapes of light between different waveguide structures, minimizing reflection and radiation losses at the coupling interface while enabling integration of different waveguide types.
Solution Approach 2:
The patent implements dynamics by creating a transition region where the waveguide cross-sectional structure is not fixed but gradually changes along the propagation direction. This dynamic structure allows the waveguide to adapt its geometry to match different operational requirements, enabling seamless coupling between ridge and buried waveguide structures.
2Device complexity
If the InP burying/cladding layer is used to surround the core layer in a buried structure, then structural simplicity is maintained, but current paths are generated that bypass the core layer reducing current injection efficiency
Solution Approach 1:
The patent applies local quality by differentiating the electrical properties of cladding layers in different regions. The first cladding layer is designed with high electrical resistance to block current paths, while the second cladding layer has different properties. This localized differentiation of material properties allows the structure to simultaneously maintain simplicity and prevent current leakage paths that would bypass the core layer.
Solution Approach 2:
The patent uses composite materials by combining cladding layers with different electrical resistance characteristics. The first cladding layer uses a material or structure optimized for optical confinement with high electrical resistance, while the second cladding layer provides additional optical confinement. This composite structure addresses both optical performance and current injection efficiency requirements.
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 efficiently injects current into the core layer of the buried waveguide, reduces optical loss by matching the refractive indices and electrical resistances, and maintains efficient operation by minimizing radiation and reflection.
Implementation Method 1
a core layer 109, 301 having a refractive index higher than a refractive index of the substrate 101
Implementation Method 2
a current blocking layer 104 having electrical resistance higher than electrical resistance of the core layer 109, 301
Data Source
AI summary
The object is to provide a technology capable of efficiently injecting a current into a core layer of a buried waveguide. On one end side of the substrate, a buried waveguide including a core layer, a cladding layer, and a current blocking layer is disposed, both sides of the core layer in a layer-stacking direction are sandwiched by the cladding layer, and both sides of the core layer in a width direction that is perpendicular to the layer-stacking direction are sandwiched by the current blocking layer. On another end side of the substrate, a ridge waveguide including the core layer and the cladding layer is disposed, and both sides of the core layer in the layer-stacking direction are sandwiched by the cladding layer.