Bridge-Waveguide for Silicon Electro-Optical Coupling
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Solution Overview
Problem
Conventional electro-optically active devices suffer from significant losses due to faceted or bending regions in the electro-optically active EPI stack, which can lead to defects and reduced optical coupling efficiency.
Innovation Solution
The method involves removing these faceted regions and replacing them with a filling material of similar refractive index to form a bridge-waveguide between the SOI waveguide and the electro-optically active stack, eliminating direct contact and reducing defects, and using a liner to prevent exposure to the atmosphere during subsequent processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If faceted or bending regions are present in the EPI stack, then the device structure is simpler to fabricate, but significant optical losses occur
Solution Approach 1:
The faceted or bending regions that cause optical losses are removed from the EPI stack. The patent extracts these harmful regions and replaces them with a filling material, thereby eliminating the source of optical loss while maintaining device functionality.
Solution Approach 2:
A filling material with refractive index matched to the waveguide material is introduced as an intermediary to replace the removed faceted regions. This intermediary material bridges the gap between the EPI stack and waveguide, eliminating optical losses while maintaining structural continuity.
2Manufacturing precision
If faceted regions are removed and replaced with filling material, then optical coupling efficiency increases, but manufacturing process becomes more complex
Solution Approach 1:
The refractive index of the filling material is carefully selected to match the waveguide material, creating an optically invisible interface. This parameter matching eliminates reflection and scattering losses, significantly improving optical coupling efficiency.
Solution Approach 2:
The manufacturing process is divided into distinct steps: etching the cavity, growing the EPI stack, removing faceted regions, applying liner, and filling with refractive index matched material. This segmentation allows each step to be optimized independently while achieving high overall precision.
3Reliability
If liner is added to line the channel, then defects are reduced and yield increases, but device structure becomes more complex
Solution Approach 1:
A liner layer is applied beforehand to protect the channel walls during subsequent filling and processing steps. This protective layer prevents defects from forming at the interface between the filling material and channel walls, thereby increasing yield.
Solution Approach 2:
The liner acts as an intermediary protective layer between the channel structure and the filling material. It prevents direct contact that could cause defects, while being thin enough to maintain optical performance.
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 approach enhances optical coupling efficiency, simplifies the manufacturing process, and increases yield by eliminating the need for an insulator layer and reducing defects, while maintaining comparable optical performance to devices without a liner.
Implementation Method 1
the lined channel is filled with a filling material with a refractive index similar to that of a material forming a sidewall of the cavity, to thereby form a bridge-waveguide in the channel between the SOI waveguide and the electro-optically active stack
Data Source
Figure 1~2A
Figure 2
Figure 2B~2C
AI summary
A silicon based electro-optically active device and method of producing the same. The silicon based electro-optically active device comprising: a silicon-on-insulator (SOI) waveguide; an electro-optically active waveguide including an electro-optically active stack within a cavity of the SOI waveguide; and a lined channel between the electro-optically active stack and the SOI waveguide, the lined channel comprising a liner; wherein the lined channel is filled with a filling material with a refractive index similar to that of a material forming a sidewall of the cavity, to thereby form a bridge-waveguide in the channel between the SOI waveguide and the electro-optically active stack.