Cladless Fiber Light Stripper for Low NA Cladding Removal
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Solution Overview
Problem
Existing fiber laser designs face challenges in effectively stripping low numerical aperture (NA) cladding light, which can cause fiber burn and increased thermal load, especially in single clad fibers, due to its nearly straight propagation and difficulty in being removed by conventional cladding light strippers.
Innovation Solution
The use of cladless optical fibers with a pure fused silica core and a low index polymer buffer, where a light stripper is attached directly to the exposed fiber core, utilizing a Fluorine-doped glass tube with roughened surfaces to scatter and diffract low NA light, ensuring efficient removal and maintaining high NA light extraction, thereby eliminating the need for thinning the fiber glass cladding and optimizing fiber bundling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional cladding light strippers are used, then high NA cladding light can be stripped, but low NA cladding light cannot be effectively removed due to its nearly straight propagation
Solution Approach 1:
The patent removes the glass cladding layer to expose the fiber core directly, eliminating the cladding structure that prevents effective low NA light stripping. This extraction of the cladding enables the light stripper to contact and remove low NA cladding light that would otherwise propagate straight through the cladding-unstripped fiber.
Solution Approach 2:
The patent introduces a light stripper as an intermediary component that couples directly to the exposed fiber core. This light stripper acts as a mediator to scatter and redirect low NA cladding light, enabling its removal without requiring cladding thinning or complex fiber structure modifications.
2Loss of energy
If glass cladding is thinned to improve light stripping, then low NA light can be removed, but fiber strength and manufacturing complexity are reduced
Solution Approach 1:
Instead of thinning the cladding, the patent completely removes (extracts) the glass cladding layer, exposing the fiber core. This eliminates the need to compromise fiber strength by partial thinning while enabling complete low NA light removal through direct light stripper-to-core coupling.
Solution Approach 2:
The patent changes the structural parameter of the fiber by removing the cladding layer entirely, transitioning from a cladless fiber design to a standard cladded fiber design. This parameter change enables effective light stripping while preserving fiber strength, as the complete cladding removal is performed once during manufacturing rather than requiring ongoing thinning.
3Illumination intensity
If pigtail fiber with tight coupling spot and launch NA is used, then high brightness is achieved, but design room is very limited
Solution Approach 1:
The patent changes the launch NA parameter by using a light stripper with a larger acceptance angle than the fiber's launch NA. This parameter change increases design flexibility, allowing a wider range of coupling spots and launch conditions while maintaining high brightness, as the light stripper can handle both low and high NA light effectively.
4Loss of energy
If cladless fiber is used, then low NA light stripping is improved, but fiber bundling and handling become more difficult
Solution Approach 1:
The patent uses a polymer buffer coating that replicates the protective function of glass cladding, providing mechanical protection and ease of handling for cladless fibers. This copying of the cladding's protective role allows effective low NA light stripping while maintaining fiber bundling ease, as the polymer buffer prevents fiber damage during installation and operation.
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 approach efficiently strips both low and high NA light, maintains the launch NA throughout the optical fiber, and allows for tighter fiber bundling, reducing thermal loads and fiber burn risks while conserving pump brightness and reducing costs by eliminating the need for cladding thinning.
Implementation Method 1
utilizing a Fluorine-doped glass tube with roughened surfaces to scatter and diffract low NA light
Implementation Method 2
utilizing a Fluorine-doped glass tube with roughened surfaces to scatter and diffract low NA light
Implementation Method 3
efficiently strips both low and high NA light
Implementation Method 4
maintains the launch NA throughout the optical fiber
Data Source
AI summary
Some embodiments may include a packaged laser diode assembly, comprising: a length of optical fiber having a core and a polymer buffer in direct contact with the core, the length of optical fiber having a first section and a second section, the first section of the length of optical fiber including a tip of an input end of the optical fiber, wherein the polymer buffer covers only the second section of the first and second sections; one or more laser diodes to generate laser light; means for directing a beam derived from the laser light into the input end of the length of optical fiber; a light stripper attached to the core in the first section of the length of optical fiber. Other embodiments may be disclosed and/or claimed.