Optical Sub-Module Thermal Expansion Management
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Solution Overview
Problem
In optical communication, existing optical modules face challenges in maintaining a stable optical path and reducing optical power loss due to thermal expansion issues, as the adhesive layer's expansion generates extrusion forces that deform the casings, affecting the optical device's position and performance.
Innovation Solution
The optical sub-module design features a first casing with a groove structure and a second casing connected via an adhesive layer with a higher coefficient of thermal expansion, where the first casing is more prone to deform, providing space for the adhesive's expansion and reducing deformation of the second casing, thus maintaining the optical path and optical power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an adhesive layer with high coefficient of thermal expansion is used to connect the first casing and second casing, then the bonding strength and sealing performance are improved, but the extrusion force generated during thermal expansion deforms the second casing, affecting optical path stability
Solution Approach 1:
The housing is divided into two separate casings (first casing and second casing) connected by the adhesive layer. This segmentation allows the first casing to expand independently during thermal cycles, absorbing expansion forces before they reach the second casing and optical device, thereby reducing deformation while maintaining bonding strength.
Solution Approach 2:
The adhesive layer is strategically positioned only at specific locations where thermal expansion forces need to be absorbed, rather than uniformly across the entire structure. This localized application allows the first casing to deform in controlled areas without affecting the overall optical path stability.
2Area of stationary object
If the adhesive layer is disposed close to the top wall of the first casing, then the bonding area is increased, but the extrusion force during thermal expansion directly affects the optical device positioned on the second casing
Solution Approach 1:
The adhesive layer is positioned at the bottom of the first casing rather than near the top wall, changing the spatial dimension of bonding. This repositioning allows the bonding area to be maximized at the base where expansion forces are naturally directed away from the optical device, converting a potentially harmful force distribution into a beneficial one.
3Stability of the object's composition
If the second casing is made rigid to maintain optical device position, then the optical path stability is improved, but the thermal expansion stress from the adhesive layer cannot be relieved, causing deformation of the first casing
Solution Approach 1:
The adhesive layer acts as an intermediary element between the first and second casings. It provides a compliant interface that allows the first casing to deform under thermal stress while maintaining the structural integrity and position stability of the second casing and optical device.
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 design reduces the deformation of the second casing by approximately four times, stabilizing the optical path and enhancing the optical module's performance by allowing the first casing to absorb stress and dissipate heat effectively.
Implementation Method 1
a coefficient of thermal expansion of the adhesive layer is greater than a coefficient of thermal expansion of the first casing and a coefficient of thermal expansion of the second casing
Data Source
AI summary
An optical sub-module includes a first casing, a second casing, an adhesive layer and an optical device. The first casing has a top wall and a first sidewall. The second casing has a bottom wall and a second sidewall. A height of the second sidewall in a thickness direction of the bottom wall is greater than a height of the first sidewall in a thickness direction of the top wall, and the second casing and the first casing is connected to form a chamber. The adhesive layer is disposed between a surface of the first sidewall and a surface of the second sidewall, and a coefficient of thermal expansion of the adhesive layer is greater than a coefficient of thermal expansion of the first casing and a coefficient of thermal expansion of the second casing. The optical device is disposed in the chamber and fixedly connected to the second casing.