Multi-Core Optical Fiber Coating for Re-Coupled Light Suppression
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Solution Overview
Problem
Multi-core optical fibers (MCFs) experience signal quality deterioration due to light leakage into the coating, causing interference between light propagating through the core and light components re-coupled from the coating, which cannot be explained by transmission loss alone.
Innovation Solution
The MCFs are designed with a leaked light propagation suppressive coating layer on the outer periphery of the common cladding, which reflects and suppresses the re-coupled light components back into the core, preventing interference and maintaining signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If light leakage into coating is allowed to occur, then transmission loss increases, but signal quality deteriorates due to interference between core-propagated light and re-coupled light components
Solution Approach 1:
The patent converts the harmful re-coupled light components into beneficial effects by using the coating layer to reflect these components back into the core. The coating, which normally causes loss, is designed to suppress the harmful interference by reflecting re-coupled light, thereby converting a harmful effect into a beneficial signal quality improvement.
Solution Approach 2:
The patent changes the optical parameters of the coating layer by controlling its refractive index and thickness. By adjusting these parameters, the coating achieves optimal reflection of re-coupled light components while maintaining acceptable transmission loss, thus resolving the contradiction between energy loss and signal quality.
2Reliability
If coating leakage loss is increased to suppress light leakage, then signal quality improves, but transmission loss increases
Solution Approach 1:
The patent optimizes the coating layer parameters (refractive index and thickness) to achieve the best balance between suppressing re-coupled light and minimizing transmission loss. This parameter optimization allows the system to achieve good signal quality without excessive energy loss.
Solution Approach 2:
The patent employs a composite coating structure with specific refractive index combinations to achieve both reflection of re-coupled light and acceptable transmission. The multi-layer coating structure acts as a composite system that simultaneously addresses both requirements.
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 suppressive coating layer effectively reduces interference patterns and maintains signal quality by minimizing the intensity of re-coupled light components, even in wavelength ranges where light leakage is prominent, thus preventing signal deterioration.
Implementation Method 1
a leaked light propagation suppressive coating layer completely surrounding the common cladding, wherein the leaked light propagation suppressive coating layer has an attenuation index with respect to light having a wavelength within a wavelength range of from 850 nm to 1700 nm or from 1260 nm to 1625 nm to decrease the intensity of a leaked light component that re-couples to each core by reflecting on a coating surface toward each core
Data Source
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AI summary
An MCF according to the disclosure has a structure preventing deterioration in quality of optical transmission signals. The MCF comprises cores, a common cladding, and a coating. Any of the cores has a coating leakage loss of 0.01 dB/km or more at a wavelength within a wavelength range of from 850 nm to 1700 nm. The coating includes a leaked light propagation suppressive coating layer having a first optical property or a second optical property to light with a wavelength within a wavelength range of from 850 nm to 1700 nm or from 1260 nm to 1625 nm. The first optical property is defined by, as an attenuation index of the light, an absorbance per 1 µm thickness being 0.1 dB or more. The second optical property is defined by a product of absorbance per 1 µm thickness and a thickness being 0.1 dB or more.