Optical Fiber Two-Stage Cooling Process
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Solution Overview
Problem
Existing methods for reducing optical fiber transmission loss are complex and inefficient, particularly in controlling dopant species and viscosity in the core and cladding, leading to increased manufacturing complexity and time.
Innovation Solution
The method involves a two-stage cooling process for optical fiber manufacturing, where the fiber is cooled at a rate of not more than 4000°C per second at 1200-1400°C and not more than 8000°C per second at 850-1200°C, using a first slow-cooling unit and a second slow-cooling unit, respectively, with a core doped with germanium and a cladding made of SiO2, to achieve low transmission loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional heating furnace cooling method is used, then transmission loss reduction is attempted, but transmission loss is not sometimes reduced and manufacturing complexity increases
Solution Approach 1:
The cooling process is divided into two distinct stages with different cooling rates and temperature ranges. The first stage cools from 1200-1400°C at a rate of 4000°C/sec or slower, and the second stage cools from 850-1200°C at a rate of 8000°C/sec or slower. This segmentation allows precise control of viscosity and refractive index at different temperature zones, achieving low transmission loss without requiring complex dopant management systems.
Solution Approach 2:
The invention changes the cooling rate parameter as a function of temperature. By controlling the cooling rate to be 4000°C/sec or slower at 1200-1400°C and 8000°C/sec or slower at 850-1200°C, the method achieves optimal viscosity and refractive index profiles. This parameter-based control simplifies the manufacturing apparatus by eliminating the need for complex dopant addition systems while maintaining low transmission loss.
2Loss of energy
If dopant species and amount are adjusted to control viscosity, then transmission loss can be reduced, but manufacturing apparatus becomes complicated and larger
Solution Approach 1:
Instead of adjusting dopant species and amounts to control viscosity, the invention changes the cooling rate parameter. By implementing a two-stage cooling process with specific cooling rates at different temperature ranges, the method achieves optimal viscosity and refractive index control without requiring complex dopant management, thereby simplifying the manufacturing apparatus and process.
3Loss of energy
If dopant control method is used to manage refractive index, then transmission loss is reduced, but manufacturing time increases
Solution Approach 1:
The cooling process is segmented into two stages with optimized cooling rates. The first stage (1200-1400°C at 4000°C/sec or slower) and second stage (850-1200°C at 8000°C/sec or slower) are designed to achieve rapid viscosity and refractive index control. This segmented approach reduces manufacturing time compared to conventional single-stage slow cooling methods while maintaining low transmission loss through precise parameter control.
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 results in an optical fiber with a transmission loss of not more than 0.35 dB/km at 1383 nanometers, with a mode field diameter of at least 8 micrometers and a relative refractive index difference of 0.3-0.5%, effectively reducing manufacturing complexity and time while maintaining low transmission loss across a wide wavelength range.
Implementation Method 1
drawing an optical fiber preform softened by heating
Implementation Method 2
a first slow-cooling unit that cools the optical fiber drawn from the optical fiber preform at a cooling rate of not more than 4000° C. per second at a temperature of the optical fiber of a not less than 1200 to 1400° C.
Implementation Method 3
a second slow-cooling unit that cools the optical fiber at a cooling rate of not more than 8000° C. per second at a temperature of 850 to 1200° C. of the optical fiber
Data Source
AI summary
A method for manufacturing an optical fiber by drawing an optical fiber preform softened by heating, includes cooling the optical fiber at a cooling rate of not more than 4000° C. per second at a temperature of 1200 to 1400° C. of the optical fiber; and cooling the optical fiber at a cooling rate of not more than 8000° C. per second at a temperature of 850 to 1200° C. of the optical fiber. A drawing rate of the optical fiber is not less than 1000 meters per minute.