Optical Coupling Assembly for Thermal-Stable Fiber Alignment
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Solution Overview
Problem
Optical coupling between an optical fiber and an optical chip is affected by temperature changes induced by a thermoelectric cooler, leading to decreased coupling efficiency, especially for high-performance components with small mode field diameters, and traditional gluing methods are unreliable and limit the use of tapered or lensed fibers.
Innovation Solution
An optical coupling assembly with a fiber holder bonded to portions of the optical unit and/or temperature adjusting element, oriented perpendicular or obliquely to the optical axis, stabilizes the optical path and includes a free beam region to mitigate alignment changes due to temperature fluctuations, using a thermoelectric cooler for temperature adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a thermoelectric cooler is used to cool the optical chip, then the temperature of the optical unit is adjusted, but temperature changes cause relative movement between the optical fiber and the optical chip, decreasing coupling efficiency
Solution Approach 1:
The fiber holder is segmented into multiple bonding portions (first portion bonded to optical unit, second portion bonded to temperature adjusting element) that are oriented perpendicular or obliquely to the optical axis. This segmentation allows differential thermal expansion without compromising the optical coupling, as each segment can move independently relative to the other during temperature changes.
Solution Approach 2:
The bonding portions are arranged in a plane perpendicular or oblique to the optical axis rather than along the optical axis. This dimensional reorientation allows thermal expansion to occur in directions that do not affect the precise alignment between the optical fiber ending and the optical unit, effectively decoupling thermal movement from optical path disruption.
2Reliability
If the optical fiber is glued to the optical chip to prevent coupling efficiency decrease, then alignment stability is improved, but module reliability decreases and tapered or lensed fibers cannot be used
Solution Approach 1:
Instead of a single rigid glue bond, the fiber holder creates segmented bonding zones at different orientations. This allows the system to maintain alignment stability through the distributed bonding structure while accommodating different fiber types (including tapered and lensed fibers) that require specific end configurations, as the bonding is separated from the optical coupling interface.
Solution Approach 2:
The fiber holder acts as an intermediary component between the optical fiber and the optical unit/temperature adjusting element assembly. It provides the bonding function while allowing the optical fiber to maintain its specific geometry (tapered, lensed, or standard) without being directly glued to the optical chip, thus enabling versatility in fiber type selection while maintaining alignment stability.
3Device complexity
If the fiber holder is bonded along the optical axis, then alignment is simplified, but thermal expansion causes misalignment and compact design is compromised
Solution Approach 1:
The bonding portions are reoriented from the optical axis direction to a plane perpendicular or oblique to the optical axis. This dimensional change allows the bonding structure to accommodate thermal expansion in directions that do not affect the optical path, maintaining alignment stability under temperature changes while still providing a relatively simple bonding configuration.
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
The solution maintains precise and stable optical coupling, allowing for a compact design while compensating for thermal strain, thereby enhancing reliability and maintaining alignment despite temperature changes.
Implementation Method 1
a thermoelectric cooler (TEC) for cooling the optical chip
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to an optical coupling assembly (1), comprising at least one optical fiber (2); an optical unit (3) configured to receive light from the optical fiber (2) and/or to emit light to be coupled into the optical fiber (2); a temperature adjusting element (4) configured to adjust a temperature of the optical unit (3); at least one fiber holder (5) on which the optical fiber (2) is mounted in such way that a at least a portion of an optical path between an ending (21) of the optical fiber (2) and the optical unit (3) is a free beam region, wherein the fiber holder (5) is bonded to at least one portion of the optical unit (3) and/or the temperature adjusting element (4), the at least one portion extending along or in a plane which is orientated perpendicular or obliquely at angle to an optical axis (A) of the optical unit (3).