Liquid Metal Clad Mode Absorber for High Power Fiber Lasers
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Solution Overview
Problem
High power single mode fiber laser systems face issues with undesirable cladding-guided light causing overheating and damage due to low mechanical stress resistance and thermal conductivity of existing cladding mode absorbers, leading to reduced beam quality and potential destruction of optical components.
Innovation Solution
A metal light clad energy absorber filled with liquid metals and their alloys is used, providing high thermal conductivity and mechanical stress resistance, integrated with a heat sink for effective heat dissipation, and textured to improve adhesion to the quartz cladding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If polymer compound absorbers are used to remove cladding light, then light absorption capability is provided, but thermal conductivity is low leading to high temperatures and destruction
Solution Approach 1:
The patent changes the material parameter from polymer compound to liquid metal, fundamentally altering the thermal conductivity property. Liquid metals have inherently high thermal conductivity, which allows the absorber to dissipate heat efficiently and operate at high temperatures without destruction, while maintaining light absorption capability through controlled coupling with the fiber cladding.
Solution Approach 2:
The patent creates a composite structure by combining liquid metal with a protective coating layer. The liquid metal core provides high thermal conductivity and light absorption, while the protective coating prevents direct contact between the liquid metal and the fiber cladding, ensuring structural integrity and controlled optical coupling. This composite approach resolves the contradiction by combining materials with complementary properties.
2Loss of energy
If polymer compound absorbers are used, then cladding light removal is achieved, but mechanical stress resistance is low causing micro bending losses and mode excitation
Solution Approach 1:
The patent changes the mechanical property parameter by substituting polymer compound with liquid metal. Liquid metals possess superior mechanical strength and elasticity, enabling the absorber to withstand mechanical stresses during fiber bending and handling without causing micro bending losses or exciting high order modes, while maintaining effective cladding light removal.
3Temperature
If liquid metal is used for high thermal conductivity, then heat dissipation is improved, but adhesion to quartz cladding is poor
Solution Approach 1:
The patent introduces a protective coating layer as an intermediary between the liquid metal and the quartz fiber cladding. This coating serves dual functions: it prevents direct contact that would cause poor adhesion and potential contamination, while still allowing controlled optical coupling for light absorption. The coating acts as a mediator that enables the liquid metal to function effectively without suffering from its inherent poor adhesion to quartz.
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 metal light clad energy absorber effectively absorbs high power cladding-guided light, maintaining structural integrity at elevated temperatures and reducing mechanical stresses, thereby enhancing the reliability and quality of the fiber laser system.
Implementation Method 1
The filling is selected to absorb light
Implementation Method 2
high thermo-conductivity
Implementation Method 3
Due to high thermo-conductive characteristics, the absorber operates as effective heat evacuating media between quartz and metal heatsink
Data Source
Figure 1~2
Figure 3~5
AI summary
A clad absorber unit is provided on a passive fiber of a high power fiber laser system and operative to trap and remove high order modes propagating along the clad of the passive fiber, The mode absorber has a composition made from one or more liquid metals and alloys thereof which are placed in the opening formed in the sheath of the passive fiber. The composition is configured to remove from the cladding the MM light having a predetermined light power which heats the composition at a temperature lower than a threshold temperature at which the absorber may be damaged.