Optical Fiber Core Chlorine Gradient for Attenuation Control
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Solution Overview
Problem
The existing optical fibers with alkali metal elements in the core face increased attenuation due to glass defects during fiber-drawing, which is exacerbated by low chlorine concentrations, leading to higher manufacturing costs and attenuation issues.
Innovation Solution
The optical fiber design features a core with a higher average chlorine concentration in the inner core than the outer core, along with the inclusion of fluorine to reduce viscosity and control hydrogen loss, while maintaining a refractive index difference between the core and cladding, thereby reducing attenuation and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the core contains alkali metal elements to reduce Rayleigh scattering attenuation, then the viscosity of the core is reduced and glass re-arrangement is facilitated, but glass defects occur and attenuation increases when chlorine concentration is low
Solution Approach 1:
The patent applies local quality by creating distinct chlorine concentration zones within the core structure. The inner core (radius r0/2) has chlorine concentration of 0-100 mol ppm while the outer core (inside radius r0/2, outside radius r0) has chlorine concentration of 500-4000 mol ppm. This localized differentiation allows the inner core to maintain low viscosity for glass re-arrangement while the outer core provides sufficient chlorine to prevent glass defects, thereby resolving the contradiction between reducing Rayleigh scattering and preventing glass defects.
2Reliability
If the chlorine concentration of the outer core is increased to restore glass defects, then glass defect occurrence is restrained, but manufacturing cost increases
Solution Approach 1:
The patent optimizes manufacturing cost by applying local quality principles to chlorine distribution. Instead of uniformly high chlorine concentration throughout the core, the invention concentrates chlorine specifically in the outer core region (500-4000 mol ppm) where it is most needed for defect restoration, while keeping the inner core chlorine concentration low (0-100 mol ppm). This targeted approach reduces the total amount of chlorine required compared to uniform distribution, thereby lowering manufacturing costs while maintaining effective glass defect prevention.
3Stability of the object's composition
If the chlorine concentration of the inner core is decreased to control crystallization, then crystallization is controlled, but glass defects increase during fiber-drawing
Solution Approach 1:
The patent resolves this contradiction by implementing local quality with spatially differentiated chlorine concentrations. The inner core is maintained at low chlorine concentration (0-100 mol ppm) to control crystallization and maintain compositional stability, while the outer core is enriched with chlorine (500-4000 mol ppm) to prevent glass defects during fiber-drawing. This localized differentiation allows each region to perform its specific function without interfering with the other, simultaneously achieving crystallization control and glass defect prevention.
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 design effectively restrains the increase in attenuation caused by glass defects and reduces manufacturing costs by optimizing chlorine distribution within the core, ensuring lower attenuation and preventing crystallization, while allowing for single-mode operation at 1550 nm.
Implementation Method 1
the viscosity of the core is reduced and the re-arrangement of glass is facilitated while the optical fiber preform is drawn into the optical fiber
Implementation Method 2
the occurrence of glass defects is restrained as the chlorine connects with the alkali metal group
Implementation Method 3
The cladding encloses the core and has a refractive index smaller than that of the core
Data Source
AI summary
The optical fiber offered is capable of not only restraining the attenuation due to glass defects, but also reducing the increase of manufacturing cost. The optical fiber is made of silica glass and includes a core and a cladding. The cladding encloses the core and has a refractive index smaller than that of the core. When the core is divided into inner core and outer core at half of the radius of the core, the average chlorine concentration of the inner core is larger than that of the outer core. The core includes any of the alkali metal group.