Optical Fiber Bundle Termination Using Refractive Index Matching Adhesive
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Solution Overview
Problem
Existing methods for terminating fiber bundles are expensive and not suitable for applications with high cost pressure, such as the automobile sector, and are difficult to implement in poorly accessible areas, often requiring polishing of the end surfaces which increases coupling loss.
Innovation Solution
A method involving a sleeve with a transparent material and a filler adhesive of higher refractive index than the sleeve, allowing the fiber bundle to be inserted and fixed without polishing, using a transparent filler that cures to form a light guide with minimal coupling loss, enabling termination at room temperature and in constrained spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional crimping or adhesive bonding methods are used to terminate fiber bundles, then the connection is secure, but the coupling loss increases and the process becomes expensive
Solution Approach 1:
A transparent adhesive with higher refractive index than the sleeve material is introduced as an intermediary substance between the fiber bundle and the sleeve. This adhesive serves dual purposes: it bonds the fibers securely to the sleeve while simultaneously acting as an optical medium that minimizes coupling loss by matching the refractive index requirements for optimal light transmission.
Solution Approach 2:
The refractive index parameter of the bonding medium is changed from traditional low-index materials to a transparent adhesive with higher refractive index. This parameter change enables the adhesive to function both as a mechanical bonding agent and as an optical waveguide, thereby reducing coupling loss without increasing manufacturing complexity.
2Loss of energy
If the end surface of the fiber bundle is ground and polished to minimize coupling loss, then coupling loss is reduced, but the process becomes complex and unsuitable for poorly accessible areas
Solution Approach 1:
The complex polishing step is extracted and removed from the termination process. Instead of requiring precise mechanical polishing of the fiber end surface, the invention uses a transparent adhesive that automatically provides optimal optical coupling when the fibers are simply inserted into the sleeve and the adhesive is applied.
Solution Approach 2:
The transparent adhesive performs the optical function previously requiring manual polishing. When the adhesive cures, it creates a smooth, optically optimized interface between the fibers and the sleeve, eliminating the need for external polishing operations and making the process suitable for field repairs in inaccessible locations.
3Loss of energy
If the fiber bundle is heated to achieve hexagonal cross section for dense packing, then coupling loss is reduced, but the process becomes expensive and time-consuming
Solution Approach 1:
Instead of using expensive and time-consuming thermal processing to permanently alter fiber geometry, the invention employs a simple transparent adhesive that provides the necessary optical optimization during the termination process itself. The adhesive acts as a temporary but effective optical medium that achieves low coupling loss without requiring permanent fiber modification.
4Loss of energy
If traditional termination methods are used, then coupling loss is minimized, but the method is not suitable for applications with high cost pressure such as the automobile sector
Solution Approach 1:
The transparent adhesive serves multiple functions simultaneously: it provides mechanical bonding between the fiber bundle and sleeve, acts as an optical waveguide to minimize coupling loss, and eliminates the need for separate polishing and thermal processing steps. This multi-functionality reduces both material and process costs while maintaining optimal optical performance.
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 method provides a simple, cost-effective, and reliable way to terminate fiber bundles with minimal coupling loss, suitable for use in the automobile sector and in inaccessible areas, without the need for heat treatment or polishing, achieving optical properties comparable to traditional methods.
Implementation Method 1
a transparent filler, especially a transparent adhesive, with an index of refraction n1 is introduced into the sleeve... The index of refraction n1 of the filler, i.e., especially an adhesive, is greater than the index of refraction n2 of the sleeve. The adhesive together with the sleeve thus forms a light guide
Implementation Method 2
The individual optical fibers consist of a core covered with sheathing with a lower index of refraction. In addition, the individual fibers are arranged in a jacket... which makes it possible to achieve total reflection between the core and the sheathing
Data Source
AI summary
The invention relates to a method for terminating optical fiber bundles, wherein the fiber bundle is inserted into a sleeve which is filled with adhesive.