Laser-Induced Damage Threshold Measurement in Optical Fiber
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Solution Overview
Problem
Current methods for measuring laser-induced damage thresholds in optical fibers are hindered by the inability to focus laser beams within the fibers due to their design, which prevents the creation of high power density areas necessary for effective damage testing.
Innovation Solution
A system and method utilizing controlled simultaneous external and internal irradiation of the optical fiber core with separate laser beams, allowing for localized high intensity areas within the fiber core by directing a second laser beam through the fiber's exterior and into its core, using an axicon and immersion liquid to minimize reflections and aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a laser beam is propagated through the optical fiber core, then the fiber can be tested for damage threshold, but the beam cannot be focused to create high power density areas necessary for effective damage testing
Solution Approach 1:
The patent introduces an immersion liquid with refractive index matching the fiber core as an intermediary medium. This liquid surrounds the fiber and enables the external laser beam to enter the core without total internal reflection, allowing focusing to create high power density areas while maintaining the fiber's structural integrity and optical properties
Solution Approach 2:
The patent changes the dimensional approach by directing the laser beam from the external dimension (through the cladding and into the core) rather than only from the fiber end. This enables focusing within the fiber volume to create localized high power density regions for damage threshold testing
2Reliability
If the optical fiber design maintains total internal reflection at the core-cladding boundary, then the fiber operates efficiently, but the beam cannot be influenced from outside to create focused areas
Solution Approach 1:
The patent changes the refractive index parameter of the surrounding medium by introducing immersion liquid that matches the core's refractive index. This parameter change eliminates the total internal reflection condition at the cladding interface, allowing external beam control while the fiber maintains its operational efficiency during normal operation without the liquid
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
Enables the measurement of laser-induced damage thresholds by creating high power density areas within the fiber core, allowing for the observation and quantification of damage under controlled power exposure, thereby evaluating the robustness of optical fibers.
Implementation Method 1
an axicon to direct the laser beam through an input window of the cell and onto an exterior surface of the optical fiber substantially completely around a perimeter of the optical fiber
Implementation Method 2
The cell may contain an immersion liquid. The immersion liquid may have a refractive index substantially similar to a refractive index of a cladding of the optical fiber to permit a substantial portion of the laser beam to pass through the cladding and into the core
Data Source
AI summary
A system for measuring a laser-induced damage threshold in an optical fiber may include a lens to direct a first laser beam through a core of the optical fiber. The system may also include an optical arrangement to direct a second laser beam through an exterior surface of the optical fiber and into the core of the optical fiber at a preselected location of the optical fiber to provide a predetermined power density at the preselected location, wherein the optical arrangement causes the second laser beam to be directed into the optical fiber substantially completely around a perimeter of the optical fiber to provide the predetermined power density.