Optical Module Thermal Stress Isolation via Suspended Mounting
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Solution Overview
Problem
Existing optical modules face challenges in maintaining stable optical coupling between array lenses and optical hybrid devices due to temperature changes, leading to increased coupling loss and reduced efficiency.
Innovation Solution
The optical module design incorporates a base with a flat-plate-like shape, a board with metallic patterns arranged in a specific direction, and an array lens system where one lens is optically coupled to one port and the other lens to another port, with the metallic patterns positioned to minimize temperature-induced distance changes between optical input ports, using gold-tin alloy solders for joining, which reduces residual stress and warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mounting methods are used to fix optical hybrid devices on the board, then the devices can be securely mounted, but temperature changes cause distance variations between optical input ports and array lenses leading to increased coupling loss
Solution Approach 1:
The patent changes the physical parameters of the mounting structure by introducing a suspended configuration where the optical hybrid device is not directly fixed to the board but held in a suspended state. This allows the device to thermally expand and contract without transmitting stress to the optical ports, maintaining precise alignment with the array lenses across temperature variations.
Solution Approach 2:
The mounting structure is segmented into separate functional zones: a fixed board structure, a suspended mounting region for the optical hybrid device, and a stress-isolated connection system. This segmentation allows different parts to respond independently to temperature changes, preventing distance variations between optical ports and lenses.
2Strength
If rigid fixing methods are used to secure the optical hybrid device, then the device is firmly mounted, but thermal expansion and contraction cause stress and warpage affecting optical alignment
Solution Approach 1:
The patent employs a flexible mounting approach where the optical hybrid device is suspended rather than rigidly fixed, allowing the mounting structure to flex and accommodate thermal expansion and contraction. This flexibility prevents stress accumulation and warpage while maintaining secure mounting and optical alignment.
Solution Approach 2:
The mounting system transitions from a static rigid fixation to a dynamic suspended configuration that can adapt to thermal changes. The optical hybrid device is held in a state that allows controlled movement with temperature variations, preventing stress buildup while maintaining optical coupling integrity.
3Force
If direct soldering is used to attach the optical hybrid device to the board, then strong mechanical bonding is achieved, but residual stress from cooling causes distance changes between optical ports and lenses
Solution Approach 1:
The patent extracts the optical hybrid device from direct contact with the board structure, suspending it independently. This separation eliminates the transmission of thermal stress from the board to the device during cooling, preventing distance changes between optical ports and lenses while maintaining secure mounting through alternative suspension mechanisms.
Solution Approach 2:
An intermediary mounting structure is introduced between the board and the optical hybrid device. This intermediary layer acts as a stress buffer during thermal cycling, absorbing residual stress from cooling without transmitting it to the optical ports, thereby maintaining precise alignment with the array lenses.
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 stabilizes optical coupling and reduces coupling loss to less than -0.3 dB, maintaining efficient signal transmission and optical characteristics across temperature variations.
Implementation Method 1
The second surface of the board is joined to the first surface of the base by using a first solder. The fourth surface of the optical circuit element is joined to the first metallic pattern and the second metallic pattern by using a second solder.
Implementation Method 2
The array lens is fixed onto the first surface of the base so that one of the two lenses is optically coupled to one of the two ports of the optical circuit element and the other of the two lenses is optically coupled to the other of the two ports of the optical circuit element.
Data Source
AI summary
An optical module includes a base having a first surface, a board having a second surface and a third surface, an optical circuit element having a fourth surface, a fifth surface and two ports, and an array lens. The first surface is joined to the second surface by a first solder. The third surface has a first metallic pattern and a second metallic pattern that are joined to the fourth surface by a second solder. The array lens is fixed onto the first surface of the base so as to be optically coupled to the two ports provided at one end of the optical circuit element in the first direction. The first metallic pattern is formed closer than the second metallic pattern to the one end of the optical circuit element in the first direction and is formed between the two ports in the second direction.