Structured Fiber Retainer for Moisture-Stable Silicon Photonics Assembly
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Solution Overview
Problem
The assembly of silicon photonics circuits with optical fibers is prone to misalignment and failure due to moisture absorption by the adhesive polymer, leading to fiber displacement and delamination, which is exacerbated by environmental factors like relative humidity, causing degradation in optical coupling efficiency.
Innovation Solution
A fiber retaining apparatus with structured surfaces, such as squares, rectangles, or U-shapes, is used to secure the fiber in alignment within the v-grooves of silicon photonics circuits, reducing the volume of adhesive polymer and minimizing moisture absorption effects, thereby maintaining fiber alignment despite environmental changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If adhesive polymer is used to bond fiber to v-groove, then fiber alignment is achieved, but moisture absorption causes volume expansion and fiber displacement
Solution Approach 1:
The adhesive polymer is segmented into discrete droplets rather than a continuous layer. Each droplet is independently positioned and sized to provide minimal necessary adhesion while reducing overall polymer volume. This segmentation limits the total moisture absorption capacity and prevents uniform expansion that would cause fiber displacement.
Solution Approach 2:
The polymer's physical state is changed from a continuous bonded layer to discrete droplets. This parameter change reduces the polymer's volume by over 50%, thereby reducing its moisture absorption capacity and minimizing volume expansion effects. The droplet configuration also improves evaporation rate and reduces long-term adhesion degradation.
2Ease of operation
If conventional adhesive polymer assembly is used, then fiber positioning is achieved, but polymer volume expansion due to moisture absorption causes upward shift in fiber alignment
Solution Approach 1:
The adhesive is divided into multiple small droplets distributed across the bonding area. This segmentation reduces the total polymer volume and creates multiple independent bonding points that collectively maintain fiber position without the expansive forces generated by a continuous polymer layer absorbing moisture.
Solution Approach 2:
The adhesive polymer configuration is changed from a continuous film to discrete droplets with controlled volume. This parameter change reduces the polymer mass and volume, thereby reducing the total moisture absorption capacity and minimizing the upward shift in fiber alignment caused by polymer expansion.
3Strength
If polymer adhesive is applied to secure fiber, then fiber bonding is achieved, but adhesion strength decreases due to moisture absorption and volume expansion
Solution Approach 1:
The adhesive polymer is segmented into discrete droplets rather than applied as a continuous layer. This segmentation reduces the total polymer volume and creates multiple localized bonding zones. Each droplet maintains sufficient adhesion strength while the distributed configuration allows for better stress distribution and reduced overall degradation from moisture absorption.
Solution Approach 2:
The polymer's physical configuration is changed to droplets with reduced volume. This parameter change decreases the total polymer mass that can absorb moisture, thereby maintaining adhesion strength over time. The droplet form also improves evaporation rate and reduces long-term adhesion degradation compared to a continuous polymer layer.
4Manufacturing precision
If traditional active alignment process is used, then fiber to EC coupling is achieved, but manufacturing cost and time increase
Solution Approach 1:
The v-groove structure provides passive self-alignment guidance that directs the fiber to the correct position relative to the EC. The adhesive droplets then secure the fiber in this pre-determined alignment position. This self-service approach eliminates the need for complex active alignment processes while maintaining coupling precision.
Solution Approach 2:
The v-groove geometry is designed in advance to pre-establish the correct fiber-to-EC alignment relationship. The adhesive droplets are positioned to lock the fiber in this pre-aligned position. This preliminary action eliminates the need for time-consuming active alignment adjustments during assembly.
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 structured fiber retaining apparatus maintains fiber alignment with the silicon photonics circuit, reducing polymer volume by over 50% and enhancing packaging reliability, thus preventing misalignment and delamination, and improving manufacturing efficiency.
Implementation Method 1
moisture absorption by the adhesive polymer, leading to fiber displacement and delamination
Implementation Method 2
changes in material properties of adhesive polymer material, due to environmental conditions
Data Source
AI summary
The present disclosure provides an optical fiber to silicon photonics circuit (PIC) assembly method utilizing a structured fiber retaining apparatus for fiber confinement in which polymer filling volume for adhesion and refractive index matching purpose is reduced. Reduction of polymer volume result in smaller optical alignment change due to polymer material volume changes upon moisture absorption and aging, hence improving assembly reliability. In an embodiment, the assembly method and apparatus, transparent polymer material interfaces between fiber and edged coupler volume reduce more than 50% compares to conventional assembly method.