Optical Fiber Cane Consolidation Deformation Control
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Solution Overview
Problem
The formation of optical fiber canes with alkali doped inner cores experiences deformation, known as 'puddling,' during the consolidation process due to the low viscosity of the inner core glass relative to the outer core region, leading to uneven dopant redistribution and reduced usable length, which affects the quality and efficiency of the manufacturing process.
Innovation Solution
A method involving the use of a low viscosity glass core rod with a high viscosity SiO2 based soot preform, where the soot is consolidated at high temperatures (1000° C.-1600° C) with a fast heating rate to densify the soot before the core rod softens, preventing deformation and maintaining the core/outer core diameter ratio within 10%, thereby minimizing puddling and ensuring uniform alkali distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the inner core rod is heated during consolidation, then the soot consolidates and densifies, but the low viscosity core rod softens and deforms (puddles)
Solution Approach 1:
The outer core soot is consolidated and densified before the inner core rod reaches its softening point. By performing the consolidation action preliminarily, the outer core forms a rigid structure that constrains the inner core rod, preventing deformation before it occurs.
Solution Approach 2:
The patent utilizes the temperature-dependent viscosity changes of different materials. The outer core soot transitions from porous to dense at lower temperatures, while the inner core rod maintains rigidity until higher temperatures. This parameter change allows selective consolidation timing to prevent puddling.
2Productivity
If the heating rate is increased to densify soot faster, then consolidation efficiency improves, but the core rod may not have time to maintain structural integrity
Solution Approach 1:
The patent applies different thermal histories to different regions: the outer core soot experiences rapid heating and consolidation, while the inner core rod is protected by the densifying outer layer. This local quality approach allows fast overall consolidation without compromising inner core integrity.
3Adaptability or versatility
If the softening point difference between inner core and outer core is large, then processing flexibility increases, but dopant redistribution becomes uneven
Solution Approach 1:
The patent monitors and controls the consolidation process to ensure the outer core densifies to sufficient density before the inner core reaches temperatures that would cause significant dopant redistribution. This feedback control maintains composition stability while preserving processing flexibility.
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 reduces puddling, increases the usable length of the optical fiber cane, enhances process control, and improves fiber attributes by maintaining the core/outer core diameter ratio and ensuring consistent alkali concentration along the length, resulting in cost savings and improved manufacturing efficiency.
Implementation Method 1
consolidating the soot to form the outer core, by moving the preform through a heat zone to consolidate the soot
Implementation Method 2
consolidating the soot of the soot preform by exposure to hot zone at temperatures of 1000° C.-1600° C.
Implementation Method 3
heating the outer portion of the soot preform at a relatively fast heating rate, the heating rate being sufficient to densify the soot
Data Source
AI summary
According to an embodiment of the invention a method of manufacturing optical fiber cane comprises the steps of: (i) providing a core rod manufactured of relatively low viscosity glass; (ii) depositing SiO2 based soot around the core rod to form a soot preform, the soot being of relatively high viscosity material such that the softening point of the low viscosity glass is at least 200° C. lower than the viscosity of the high viscosity outer core region; and (iii) consolidating the soot of the soot preform by exposure to hot zone at temperatures of 1000° C.-1600° C. The soot is consolidated by heating the outer portion of the soot preform at a relatively fast heating rate, the heating rate being sufficient to densify the soot, so as to render the densified material with enough rigidity to confine the heated core rod and to prevent the heated core rod from puddling.