Optical Fiber Preform Sintering for Uniform Attenuation
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Solution Overview
Problem
Conventional single mode optical fibers exhibit high and non-uniform optical attenuation loss in the 1360-1460 nm E-band region due to un-collapsed top end portions of the preform, leading to wastage and increased production costs, as the top 10-15% of the fiber must be discarded to achieve uniformity.
Innovation Solution
Simultaneous sintering and collapsing of the optical fiber preform within a sintering furnace, using controlled heat treatment and vacuum to ensure complete closure of the capillary at the top end, eliminating the need for additional plugs and reducing heat loss, thereby producing fibers with uniform attenuation loss across the entire length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the top end portion of the preform is discarded to achieve uniform optical attenuation loss, then the optical fiber quality is improved, but the production cost increases and productivity decreases
Solution Approach 1:
The invention applies preliminary action by completely collapsing the capillary structure at the top end portion of the preform before fiber drawing through controlled sintering and collapsing processes. This preliminary collapse eliminates the need for discarding the top end portion, as the capillary is already closed and will not cause non-uniform attenuation in the final fiber product
Solution Approach 2:
The invention changes the physical parameters of the preform through controlled sintering temperature and vacuum conditions during the collapsing process. By adjusting these parameters, the capillary structure is completely collapsed at the top end portion, transforming it from a defective state to a usable state without material waste
2Manufacturing precision
If additional plugs are inserted to close the capillary at the top end, then the uniformity of optical attenuation loss is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The invention extracts and eliminates the need for additional plugs by implementing a complete collapsing process that closes the capillary structure through thermal and vacuum treatment. This removes the harmful element (open capillary) without introducing additional complex components or devices
Solution Approach 2:
The invention replaces the mechanical plug insertion method with a thermal-vacuum process. Instead of mechanically inserting plugs to close the capillary, the invention uses controlled sintering and vacuum conditions to cause the capillary to collapse and close naturally, simplifying the overall manufacturing system
3Measurement precision
If the preform is completely withdrawn from the furnace for observation, then the collapsing completeness can be checked, but heat loss increases and energy efficiency decreases
Solution Approach 1:
The invention maintains continuity of useful action by keeping the preform continuously in the furnace during the collapsing process. The furnace atmosphere and temperature are maintained without interruption, eliminating heat loss from withdrawal and re-insertion cycles while the collapsing action continues uninterrupted
Solution Approach 2:
The invention implements feedback by using in-situ measurement techniques that allow monitoring of the collapsing process without withdrawing the preform. This feedback mechanism enables verification of capillary collapse completeness while the preform remains in the furnace, maintaining thermal efficiency
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 method achieves low and uniform optical attenuation loss along the entire length of the optical fiber, including the top end portion, with attenuation less than 0.35 dB/Km across the 1300-1625 nm range, reducing production costs and increasing efficiency.
Implementation Method 1
the dehydrated hollow soot porous body is simultaneously sintered and collapsed inside a sintering furnace
Implementation Method 2
by doing stepwise and controlled heat treatment of the top end portion of the preform
Implementation Method 3
while providing vacuum inside the capillary
Data Source
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AI summary
A method for producing optical fiber preform capable of producing optical fiber having low and uniform optical attenuation loss along its entire length including the top end portion is provided. The method comprises carrying out simultaneously sintering and collapsing steps by inserting the dehydrated hollow soot porous body with predetermined speed in hot zone of the furnace till its top end reaches the hot zone and is left for a predetermined duration thereafter the preform is uplifted for a predetermined length at a predetermined speed to avoid heat loss in the optical preform and re-inserted in the hot zone of sintering furnace at a predetermined speed and left for predetermined duration to result in formation of the preform having collapsed capillary including at its top end.