Optical Module Adhesive Segmentation for Thermal Misalignment
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Solution Overview
Problem
The existing optical modules experience degradation in transmission characteristics due to thermal expansion of the adhesive, causing misalignment of the optical axes between the optical fiber and the optical waveguide, which affects the optical coupling efficiency.
Innovation Solution
An optical module design that includes a block attached to the optical fiber, a waveguide substrate with an embedded optical waveguide, and a base substrate, where the adhesive is strategically segmented to manage thermal expansion, with a top segment pushing back against the expansion of the bottom segment, preventing tilt and maintaining optical axis alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive is used to bond the block and waveguide substrate, then bonding strength is improved, but thermal expansion causes optical axis misalignment
Solution Approach 1:
The adhesive is divided into three distinct segments (first, second, and third segments) with different functional roles. The first segment provides bonding between the block and waveguide substrate, the second segment compensates for thermal expansion, and the third segment bonds to the base substrate. This segmentation allows each portion to address specific requirements without compromising overall performance.
Solution Approach 2:
The patent changes the physical and chemical parameters of the adhesive by using different types of adhesive materials for different segments. The first segment uses adhesive suitable for bonding the block, the second segment uses adhesive with specific thermal expansion characteristics, and the third segment uses adhesive for base substrate bonding. This parameter differentiation resolves the contradiction between bonding strength and thermal stability.
2Ease of operation
If adhesive is interposed between block and waveguide substrate, then fixation is achieved, but bulging causes tilt and misalignment
Solution Approach 1:
The adhesive structure is segmented into three portions with the second segment specifically positioned to prevent bulging. This segment acts as a buffer zone that accommodates thermal expansion without causing the block to tilt, thereby maintaining optical axis alignment while still providing effective fixation.
Solution Approach 2:
The second adhesive segment serves as an intermediary element between the block-waveguide substrate interface and the base substrate. It mediates the thermal expansion forces, absorbing the stress that would otherwise cause bulging and misalignment, while still allowing the fixation function to be performed.
3Strength
If adhesive expands due to heat, then bonding is maintained, but optical coupling efficiency degrades
Solution Approach 1:
The adhesive is segmented into three functional portions where the second segment specifically addresses thermal expansion issues. This segmentation allows the bonding function to be maintained by the first and third segments while the second segment compensates for thermal effects, preventing optical axis misalignment and maintaining transmission characteristics.
Solution Approach 2:
The patent explicitly addresses thermal expansion by designing the second adhesive segment with characteristics that compensate for thermal effects. This segment is positioned to counteract the expansion forces, preventing the block from tilting and maintaining optical coupling efficiency despite temperature changes.
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 significantly reduces angular displacement and Z-axis displacement, stabilizing optical coupling and improving transmission characteristics by suppressing thermal-induced misalignment to 1/18 of conventional examples.
Implementation Method 1
Expansion of the bulged portion due to heat tilts the fiber block, causing the optical axes of the optical fiber and the optical waveguide to misalign
Data Source
AI summary
An optical module includes: a block; a waveguide substrate including a side face, a top part of the front face of the block protruding upward from the side face, the optical fiber and the optical waveguide aligning on a coinciding optical axis; a base substrate including a top face and a sticking-out part protruding under the block from the waveguide substrate; and an adhesive bonding the block to the waveguide substrate and the base substrate. The adhesive includes a top segment located at a corner section delineated by the top part of the front face of the block and a top face of the waveguide substrate, a middle segment interposed between the front face of the block and the side face of the waveguide substrate, and a bottom segment interposed between the bottom face of the block and a top face of the base substrate.