Optical Module Thermal Stress Reduction via Local Quality
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Solution Overview
Problem
High-speed optical modules face challenges due to thermal expansion mismatches between light emitting and optical function elements, leading to stress, breakage, and optical system displacement, which increases costs and reduces reliability.
Innovation Solution
A casing with a thermal expansion coefficient matching the optical function element is used, and a material with a similar coefficient to the light emitting element is embedded in the casing to reduce thermal stress and displacement, allowing both elements to be housed in the same package without compromising reliability or optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a light emitting element and an optical function element with different coefficients of thermal expansion are mounted in the same casing, then miniaturization and cost reduction are achieved, but thermal stress and breakage occur due to thermal expansion mismatch
Solution Approach 1:
The casing is designed with different material properties in different regions: the portion housing the light emitting element has a first coefficient of thermal expansion matching the light emitting element, while the portion housing the optical function element has a second coefficient of thermal expansion matching the optical function element. This local differentiation eliminates thermal stress at each location while enabling compact integration.
2Reliability
If separate packages are used for light emitting element and optical function element, then thermal stress is reduced, but space for connecting fibers is required and cost increases
Solution Approach 1:
The light emitting element and optical function element are integrated into a single package with a specially designed casing that accommodates both elements without requiring separate packages and fiber connections. The unified package eliminates the need for polarization maintaining fibers and external connectors while managing thermal stress through differentiated material coefficients.
3Reliability
If polarization maintaining fibers are used to connect packages, then polarization is maintained, but cost increases due to high-priced fibers and alignment requirements
Solution Approach 1:
By integrating the light emitting element and optical function element into the same package, the patent eliminates the need for polarization maintaining fibers and their associated alignment procedures. The direct mounting architecture removes this costly and complex component entirely while maintaining 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 enables a compact, reliable optical module with reduced thermal distortion, eliminating the need for polarization maintaining fibers and lowering costs, while maintaining high-speed and dispersion-tolerant characteristics.
Implementation Method 1
a casing with a thermal expansion coefficient matching the optical function element is used, and a material with a similar coefficient to the light emitting element is embedded in the casing to reduce thermal stress and displacement
Data Source
AI summary
To provide a small-sized and reliable optical module in which a light emitting element and an optical function element respectively remarkably different in a coefficient of thermal expansion are mounted in the same casing, in the invention, the optical function element is mounted on the casing made of first material substantially equal in a coefficient of thermal expansion to the optical function element, a light emitting element unit including the light emitting element (for example, a thermoelectric module over which the light emitting element is mounted) is mounted on a member (base material) made of second material different from the first material and matched with the light emitting element unit in a coefficient of thermal expansion, and the member is, for example, embedded in the bottom of the casing.