Optical Fiber Assembly Ceramic Coating for Clad Mode Light Management
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Solution Overview
Problem
Conventional optical coupling devices experience coupling loss and damage to fixing materials due to mismatched mode field diameters and aberrations, leading to clad mode light leakage, which can cause heat absorption and damage when high-power laser beams interact with materials like adhesives or low-melting-point glass.
Innovation Solution
An optical fiber assembly with a capillary and ceramic material coating, where the ceramic material has a refractive index higher than the clad, is used to scatter and absorb clad mode light, preventing it from reaching the fixing material, and the ceramic material is positioned ahead of the fixing material to ensure safe light reflection and absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the outer periphery of the clad is fixed with a fixing material having a refractive index equal to or higher than the refractive index of the clad material, then the clad mode light is leaked from the clad to the fixing material, but this causes high temperature and damage to the fixing material
Solution Approach 1:
A ceramic material with refractive index equal to or higher than the clad material is introduced as an intermediary between the optical fiber and the fixing material. This ceramic layer absorbs or scatters the clad mode light before it reaches the fixing material, preventing heat absorption and damage to the fixing material while maintaining proper optical isolation.
Solution Approach 2:
The high refractive index ceramic material that would normally cause total internal reflection and confine clad mode light is instead positioned to intentionally absorb or scatter this light. The harmful clad mode light is converted into a beneficial effect by using it to illuminate the ceramic material's light-absorbing properties, thereby protecting the fixing material from thermal damage.
2Reliability
If a high-power laser beam is directly incident on the fixing material, then the fixing material is damaged by heat
Solution Approach 1:
The ceramic material serves as a protective intermediary layer between the optical fiber and the fixing material. It intercepts and absorbs or scatters both clad mode light and directly incident high-power laser beams, preventing thermal damage to the fixing material while allowing the optical coupling function to proceed normally.
3Productivity
If the light emitted from the light-emitting element is converged by a lens, then optical coupling to the optical fiber is achieved, but coupling loss occurs due to mode field diameter mismatch or lens aberration
Solution Approach 1:
The invention introduces a ceramic material with specific optical properties (refractive index equal to or higher than the clad material) to modify the optical parameters at the fiber end. This changes the light propagation characteristics to reduce coupling loss while maintaining efficient optical coupling through the lens system.
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 configuration effectively prevents clad mode light from reaching the fixing material, reducing the risk of damage and ensuring the optical fiber assembly's resistance to high-power laser emissions, thereby protecting the assembly from heat-induced damage.
Implementation Method 1
the ceramic material is used to scatter and absorb clad mode light, preventing it from reaching the fixing material
Implementation Method 2
the refractive index of the ceramic material is set equal to or higher than the refractive index of the clad... to have a predetermined contact length in an axial direction of the optical fiber
Data Source
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AI summary
Provided are an optical fiber assembly and an optical coupling device and an optical fiber coupling device provided with the optical fiber assembly. In the optical fiber assembly, damage to a fixing material is prevented by preventing clad mode light from being incident on the fixing material and the direct incidence, on the fixing material, of laser light emitted from a light-emitting element or an optical fiber is prevented to generate resistance to the emitted light. The optical fiber assembly is constituted by at least an optical fiber and a capillary, and the optical fiber is inserted into the capillary and one end of the optical fiber is protruded to the outside of the capillary. Further, the outer periphery of the optical fiber and the capillary are fixed using the fixing material and a ceramic material is disposed so as to be in contact with the entire outer circumference of the optical fiber and so as to have a predetermined contact length in the axial direction of the optical fiber. The position at which the ceramic material is disposed is set in front of the position of the fixing material as viewed from one end of the optical fiber.