Tapered Waveguide Sections for Photonics Reticle Stitching
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Solution Overview
Problem
Positional mismatches during reticle stitching in photonics chip fabrication lead to misalignment of waveguide cores at boundaries, resulting in performance degradation such as elevated insertion loss and increased back reflection.
Innovation Solution
Incorporating tapered sections in waveguide cores aligned parallel to the boundaries, allowing for efficient light transfer across chip region transitions and minimizing the impact of reticle stitching mismatches through adiabatic light transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If reticle stitching is used to fabricate large photonics chips, then chip area is increased, but positional mismatches occur at boundaries causing waveguide misalignment
Solution Approach 1:
The waveguide geometry is changed by introducing tapered sections with gradually varying width. This parameter change allows the optical mode to adapt continuously across the reticle boundary, compensating for positional mismatches and maintaining alignment precision despite the large chip area enabled by stitching.
Solution Approach 2:
The tapered section acts as an intermediary transition region between waveguides from different reticles. This intermediate structure with gradually changing dimensions mediates the optical coupling across the boundary, reducing the impact of misalignment caused by stitching errors.
2Reliability
If waveguide cores are aligned at reticle boundaries, then optical coupling is improved, but any positional mismatch causes performance degradation
Solution Approach 1:
The tapered sections are designed in advance to provide a gradual transition that cushions against the harmful effects of stitching errors. By preparing this transition region beforehand, the system becomes more robust to misalignment, reducing sensitivity to stitching errors while maintaining reliable optical coupling.
Solution Approach 2:
The gradual change in waveguide dimensions through tapered sections reduces the sensitivity to positional mismatches. This parameter transformation creates a more tolerant coupling interface that maintains reliability even when stitching errors occur.
3Ease of manufacture
If straight waveguide sections are used at boundaries, then fabrication is simpler, but light transfer efficiency is reduced due to misalignment
Solution Approach 1:
Instead of using simple straight waveguide sections, the invention introduces tapered sections with gradually varying dimensions. This parameter change increases fabrication complexity but dramatically reduces insertion loss by enabling efficient adiabatic light transfer that is tolerant to misalignment from stitching errors.
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 tapered sections enable effective light transfer with minimal optical performance impact, increased tolerance to misalignment, and improved handling of optical mode size across boundaries, reducing performance degradation caused by reticle stitching errors.
Implementation Method 1
allowing for efficient light transfer across chip region transitions and minimizing the impact of reticle stitching mismatches through adiabatic light transfer
Data Source
AI summary
Structures including a waveguide core and methods of fabricating a structure including a waveguide core. The structure comprises a photonics chip including a first chip region, a first waveguide core in the first chip region, a second chip region, and a second waveguide core in the second chip region. The first chip region adjoins the second chip region along a boundary, the first waveguide core includes a first tapered section and the second waveguide core includes a second tapered section adjacent to the first tapered section. The first tapered section has a first longitudinal axis aligned substantially parallel to the boundary, and the second tapered section has a second longitudinal axis aligned substantially parallel to the boundary.