Optical Waveguide Device Stress Reduction via Segmented Joining
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Solution Overview
Problem
Optical waveguide devices experience internal stress and potential optical component misalignment or detachment due to differences in linear expansion coefficients between the substrate, reinforcing block, and optical block, especially under temperature changes, leading to increased loss and adhesion issues in complex structures like Mach-Zehnder or folded configurations.
Innovation Solution
The optical waveguide device features a substrate with an optical waveguide and a reinforcing block, where the optical component's joining surface material has a different linear expansion coefficient, and the joining area is minimized by techniques such as notching, varying surface areas, and curving corner shapes to reduce stress, with an adhesive coating region limited by grooves to prevent excessive stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the optical component is joined to both the end surface of the substrate and the end surface of the reinforcing block to increase adhesion area, then the adhesive strength is improved, but the internal stress generated due to different linear expansion coefficients increases
Solution Approach 1:
The joining area is segmented into two distinct zones: a first joining area on the substrate and a second joining area on the reinforcing block. This segmentation allows the optical component to be distributed across multiple attachment points, reducing stress concentration in any single location while maintaining overall adhesion strength.
Solution Approach 2:
Different regions of the optical component are assigned different joining functions: the first joining area contacts the substrate while the second joining area contacts the reinforcing block. This local differentiation optimizes the adhesive interface by matching each joining area with its corresponding support structure, managing stress distribution according to the local mechanical properties of each material.
2Strength
If the joining area of the optical component is increased to improve adhesion, then the mechanical strength is improved, but the misalignment and detachment under temperature changes worsen
Solution Approach 1:
The total joining area is divided into separate first and second joining areas on different substrates (substrate and reinforcing block). This segmentation distributes the mechanical load and thermal stress across multiple interfaces, preventing the concentration of stress that would lead to misalignment or detachment while maintaining overall mechanical strength.
Solution Approach 2:
The reinforcing block acts as an intermediary element between the substrate and the optical component. By providing a second joining interface, it serves as a mediator that distributes thermal and mechanical stresses, reducing the risk of misalignment and detachment while maintaining reliable mechanical attachment.
3Area of stationary object
If the optical component is joined to both substrate and reinforcing block, then the adhesion area is increased, but the complexity of the structure increases
Solution Approach 1:
The adhesion area is segmented into two functional zones on different surfaces (substrate and reinforcing block), increasing the total adhesion area without requiring a fundamentally different joining mechanism. This segmentation achieves enhanced adhesion while maintaining a relatively simple overall structure.
Solution Approach 2:
The optical component is designed with multiple joining areas that can adhere to different substrates, giving it multi-functionality in terms of attachment. This universal joining approach increases adhesion area while avoiding the need for multiple separate components, thereby limiting the increase in structural complexity.
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 configuration effectively reduces internal stress at the joining surface, preventing optical component misalignment and detachment, thereby maintaining low insertion loss and mechanical strength across varying temperatures.
Implementation Method 1
an adhesive 15 is disposed in the first joining area and the second joining area
Implementation Method 2
a material used for a joining surface of the optical component and a material used for the substrate or the reinforcing block have at least different linear expansion coefficients
Data Source
AI summary
An optical waveguide device includes a substrate on which an optical waveguide is formed, and a reinforcing block disposed on the substrate, along an end surface of the substrate on which an input portion or an output portion of the optical waveguide is disposed, in which an optical component that is joined to both the end surface of the substrate and an end surface of the reinforcing block is provided, a material used for a joining surface of the optical component and a material used for the substrate or the reinforcing block have at least different linear expansion coefficients of a direction parallel to the joining surface, and an area of a joining portion of the optical component is set to be smaller than an area of the end surfaces including joining portions of the substrate and the reinforcing block.