Dual-Layer Edge Couplers with Curved Features for Mode Conversion
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Solution Overview
Problem
Existing edge couplers struggle to fully confine the incident mode of light due to the narrow tip of the inverse taper, leading to significant electromagnetic field distribution and increased light loss.
Innovation Solution
A dual-layer edge coupler structure with curved and tapered waveguide cores is designed, featuring a first waveguide core with a curved section and a second waveguide core with a tapered section, positioned between a semiconductor substrate, to enhance mode transformation and reduce light loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the inverse taper tip is made narrow to reduce the coupling area, then the mode transformation is enhanced, but the electromagnetic field confinement deteriorates and light loss increases
Solution Approach 1:
The edge coupler is divided into multiple discrete coupling regions along the waveguide length. Each region has a specific coupling coefficient and geometry, allowing independent optimization. This segmentation enables the system to achieve both fast mode transformation in the first region and reduced light loss in subsequent regions by adjusting the coupling strength at each segment.
Solution Approach 2:
The patent varies multiple parameters including coupling coefficient, waveguide width, and taper angle along the length of the edge coupler. By dynamically changing these parameters rather than using a uniform structure, the design achieves optimal mode transformation efficiency while minimizing light loss through careful parameter sequencing.
2Loss of energy
If the inverse taper width is increased to improve electromagnetic field confinement, then light loss is reduced, but the mode transformation capability deteriorates
Solution Approach 1:
The coupling structure is divided into multiple regions with different width characteristics. The first region has a narrower effective width for strong coupling and fast mode transformation, while subsequent regions have progressively wider sections that improve field confinement and reduce light loss, achieving both objectives through spatial segmentation.
Solution Approach 2:
The patent transitions from a single-dimensional uniform taper to a multi-dimensional structure with varying coupling coefficients and geometries along the waveguide length. This dimensional expansion allows simultaneous optimization of mode transformation and field confinement by distributing different functional requirements across different spatial dimensions.
3Device complexity
If a single-layer edge coupler structure is used to simplify the device, then manufacturing is easier, but the confinement of light and reduction of leakage to substrate is insufficient
Solution Approach 1:
The patent employs a nested structure where multiple functional layers are integrated within the edge coupler. The first waveguide core is positioned between the second waveguide core and the semiconductor substrate, creating a nested arrangement that provides enhanced light confinement and reduces leakage to the substrate while maintaining manageable manufacturing complexity through systematic layer integration.
4Productivity
If the coupling coefficient is increased to enhance mode transformation, then mode conversion is faster, but light loss and leakage to substrate increase
Solution Approach 1:
The coupling coefficient is segmented and varied along the waveguide length rather than being uniform. The first coupling region has a higher coupling coefficient for fast mode transformation, while subsequent regions have progressively lower coupling coefficients that reduce light loss and leakage, allowing the system to achieve both fast conversion and low loss through spatial segmentation of the coupling strength.
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 dual-layer edge coupler significantly reduces light loss and enables faster mode conversions by improving the confinement of light, particularly when receiving light with a small mode size, and mitigates leakage to the semiconductor substrate.
Implementation Method 1
The gradually-varying cross-sectional area of the inverse taper supports mode transformation and mode size variation associated with mode conversion when light is transferred from the light source to the edge coupler
Implementation Method 2
A photonics chip includes a photonic integrated circuit comprised of optical components, such as modulators, polarizers, and optical couplers, that are used to manipulate light received from a light source
Implementation Method 3
the tip of the inverse taper is unable to fully confine the incident mode received from the light source because the cross-sectional area of the tip is considerably smaller than the mode size
Data Source
AI summary
Structures for an edge coupler and methods of forming such structures. The structure comprises a semiconductor substrate, a first waveguide core including a curved section and an end that terminates the curved section, and a second waveguide core including a section disposed adjacent to the curved section of the first waveguide core. The first waveguide core is positioned between the second waveguide core and the semiconductor substrate.