Phase-Change Fiber Holder for Thermal Stress Control
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Solution Overview
Problem
Conventional gain-fiber mandrels cause high temperatures and non-uniform temperature gradients in optical fibers due to poor thermal contact, leading to degradation and power loss in laser systems, and induce thermal fatigue stress from the difference in thermal expansion coefficients between glass and metal.
Innovation Solution
A phase-change-based thermal-management system with point contacts between the optical fiber and a housing, using a thermal-management material that undergoes a phase change to control temperature, maintain uniformity, and minimize stress, incorporating a self-contained heat pipe or thermal chamber to manage high power levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional gain-fiber mandrels with direct continuous line contact are used, then thermal contact is improved, but temperature uniformity deteriorates and thermal stress increases
Solution Approach 1:
The patent divides the continuous line contact into discrete point contacts arranged in a circular pattern around the fiber. This segmentation allows the fiber to expand and contract independently at each point, maintaining thermal contact while eliminating the constraints that cause non-uniform temperature distribution and thermal stress.
Solution Approach 2:
The patent applies different contact characteristics to different locations on the mandrel surface. Instead of uniform continuous contact, point contacts are strategically positioned to provide localized thermal management while allowing regional thermal expansion and contraction without inducing stress.
2Temperature
If conventional gain-fiber mandrels with direct continuous line contact are used, then thermal contact is improved, but thermal stress increases due to coefficient of thermal expansion difference
Solution Approach 1:
The continuous line contact is segmented into discrete point contacts that are spaced apart around the fiber circumference. This segmentation creates independent contact points that can move relative to each other, allowing the glass fiber to expand and contract freely during thermal cycling without being constrained by continuous metal contact, thereby eliminating thermal fatigue stress.
Solution Approach 2:
The patent introduces a compliant intermediate layer or flexible mounting structure between the metal mandrel and the glass fiber at the point contacts. This intermediary accommodates the differential thermal expansion between the metal mandrel and glass fiber, preventing stress transmission while maintaining thermal contact.
3Temperature
If phase-change-based thermal management with point contacts is used, then temperature control and uniformity are improved, but device complexity increases
Solution Approach 1:
The patent incorporates a phase-change material (PCM) in direct contact with the fiber at the point contacts. The PCM undergoes phase transition (e.g., solid-liquid) at a temperature slightly above the fiber's operating temperature, absorbing excess heat during operation and releasing it during cooling cycles. This passive phase-change mechanism provides automatic temperature regulation without requiring active control systems.
Solution Approach 2:
The phase-change material provides self-regulating thermal management that automatically responds to temperature changes. When the fiber temperature approaches the PCM's phase-change temperature, the material absorbs heat through phase transition, maintaining temperature uniformity without external control or additional active cooling components.
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 effectively controls the maximum temperature, ensures temperature uniformity across the fiber cross-section, and minimizes thermal stress, enabling the handling of high power levels up to 10 kW or more while reducing the volume and weight of the fiber-laser module.
Implementation Method 1
using a thermal-management material that undergoes a phase change to control temperature, maintain uniformity, and minimize stress
Implementation Method 2
A phase-change-based thermal-management system with point contacts between the optical fiber and a housing, using a thermal-management material that undergoes a phase change to control temperature
Data Source
AI summary
A thermal-management optical-fiber packaging system that includes an optical fiber and a temperature-management device configured to remove excess heat from the optical fiber. In some embodiments, the temperature-management device includes a first housing having a first outer-perimeter surface and an inner volume facing a first inner surface (wherein the inner volume has a length), a plurality of fiber-support members coupled to, and/or integral with, the first inner surface of the first housing, wherein each of the fiber-support members has one or more small-area-of-contact supports arranged along the length of the inner volume, and wherein each small-area-of-contact support is configured to provide a small area (e.g., a point) of contact with the optical fiber, and wherein the optical fiber follows a coiled path around the inner volume. A thermal-management material surrounds the optical fiber except at those locations where the optical fiber contacts the fiber-support members.