Anti-Reflective Coating for SiGe EAM Waveguide Coupling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Integrating SiGe quantum confined Stark effect (QCSE) electro-absorption modulators (EAMs) with silicon waveguides on silicon-on-insulator platforms is challenging due to sensitivity to fabrication variations, especially with evanescent and edge coupling structures, leading to high optical coupling loss.
Innovation Solution
An optoelectronic device comprising a multi-quantum well epitaxial structure connected to silicon nitride waveguides via anti-reflective coatings, where the input and output waveguides are formed of regular silicon nitride with a refractive index of 2.2 and the anti-reflective coating is made of silicon-rich silicon nitride with a refractive index of 2.8, achieving a high coupling efficiency of 96.1% and low optical coupling loss of 0.36 dB.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SiGe QCSE EAMs are integrated with evanescent coupling structures, then optical coupling is achieved, but the device becomes too sensitive to fabrication variations
Solution Approach 1:
The patent introduces an anti-reflective coating layer as an intermediary between the SiGe QCSE EAM and the silicon waveguide. This coating layer with optimized refractive index (2.8) serves as a mediator that improves optical coupling while reducing sensitivity to fabrication variations, thereby resolving the contradiction between reliability and device complexity
Solution Approach 2:
The patent changes the refractive index parameter of the coupling interface by applying an anti-reflective coating with refractive index 2.8, which is higher than both the SiGe layer (2.4) and the silicon nitride waveguide (2.2). This parameter change optimizes optical coupling efficiency while maintaining fabrication robustness
2Reliability
If SiGe QCSE EAMs are integrated with edge coupling structures, then optical coupling is achieved, but the device is prone to failure during amorphous or SiGe filling processes
Solution Approach 1:
The anti-reflective coating acts as a protective intermediary layer during the amorphous or SiGe filling processes, preventing direct exposure of the SiGe EAM to potentially damaging processes while still enabling effective optical coupling when the waveguide is formed
3Loss of energy
If SiGe QCSE EAMs are integrated with evanescent edge coupling structures, then optical coupling is achieved, but the device becomes very sensitive to fabrication processes and SiGe regrowth process
Solution Approach 1:
The patent modifies the optical parameters at the coupling interface by introducing an anti-reflective coating with refractive index 2.8, which reduces reflection losses and improves coupling efficiency. This parameter change makes the system less sensitive to variations in fabrication processes and SiGe regrowth
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 solution provides a simple and consistent fabrication process for SiGe QCSE EAMs that is insensitive to process variations, achieving high coupling efficiency and low optical loss, thereby improving the integration of SiGe QCSE EAMs with silicon-on-insulator platforms.
Implementation Method 1
anti-reflective coatings, located between both the input waveguide and the stack and the stack and the output waveguide
Implementation Method 2
an input waveguide, arranged to guide light into the stack... an output waveguide, arranged to guide light out of the stack... formed of silicon nitride
Data Source
AI summary
An optoelectronic device and a method of manufacturing the same. The device comprising: a multi-layered optically active stack; an input waveguide, arranged to guide light into the stack; an output waveguide, arranged to guide light out of the stack; and anti-reflective coatings, located between both the input waveguide and the stack and the stack and the output waveguide; wherein the input waveguide and output waveguide are formed of silicon nitride.