Optical Fiber Cooling via Fictive Temperature Control
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Solution Overview
Problem
Existing optical fiber production methods face challenges in reducing transmission losses due to scattering caused by fluctuations in the structure of glass fibers, which are not adequately addressed by current temperature control techniques, leading to increased capital investment and decreased productivity.
Innovation Solution
An optical fiber production method involving a drawing process followed by a slow cooling process where the optical fiber is passed through multiple annealing furnaces, with controlled temperature differences between the actual temperature and fictive temperature of the glass core, optimizing the relaxation of the glass structure to minimize transmission losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the temperature of the optical fiber is controlled using complex recurrence formulas with large permitted deviations (±50°C to 100°C), then the production process is simpler to implement, but the temperature history is not sufficiently optimized leading to increased transmission losses
Solution Approach 1:
The invention changes the control parameter from absolute temperature (with large ±50-100°C deviations) to temperature difference (Tf-T) with tight control in the range of ±5°C to ±20°C. This parameter transformation enables precise control of the glass structure relaxation process while maintaining practical manufacturability.
Solution Approach 2:
The invention replaces complex iterative recurrence formula calculations with a direct control approach based on the temperature difference parameter. Instead of repeatedly calculating target temperatures through complex formulas, the system directly controls Tf-T within a specified range, simplifying the control mechanism while improving precision.
2Manufacturing precision
If the temperature history is sufficiently optimized by tightly controlling the optical fiber temperature, then transmission losses are reduced, but capital investment increases due to elongating the annealing furnace more than necessary
Solution Approach 1:
By changing from absolute temperature control to temperature difference control (Tf-T), the invention achieves effective glass structure relaxation without requiring excessively long annealing furnaces. The tight control of Tf-T in the range of ±5°C to ±20°C enables optimized temperature history with reasonable furnace dimensions.
3Manufacturing precision
If the temperature history is sufficiently optimized by tightly controlling the optical fiber temperature, then transmission losses are reduced, but productivity decreases due to decreasing the drawing rate more than necessary
Solution Approach 1:
The invention changes the control approach to managing the temperature difference (Tf-T) between fictive temperature and actual temperature. This enables achieving optimized temperature history without excessively reducing the drawing rate, thereby maintaining higher productivity while reducing transmission losses.
4Manufacturing precision
If multiple annealing furnaces are used to control the temperature difference between fictive temperature and optical fiber temperature, then transmission losses are reduced through promoted glass structure relaxation, but the device complexity increases
Solution Approach 1:
The invention segments the temperature control process into multiple stages, each managed by separate annealing furnaces. By dividing the cooling process into distinct zones with controlled temperature differences, the system achieves progressive glass structure relaxation and transmission loss reduction while maintaining manageable device complexity.
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 method effectively reduces transmission losses in optical fibers by promoting the relaxation of the glass structure, thereby decreasing scattering losses, without requiring excessive capital investment or reducing productivity.
Implementation Method 1
a slow cooling process of slowly cooling the optical fiber drawn in the drawing process. In the slow cooling process, the optical fiber is passed through a plurality of annealing furnaces
Implementation Method 2
Equation (1) below is held in a given period in the slow cooling process, where a time constant of relaxation of a structure of glass forming a core included in the optical fiber is defined as τ(T)
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An optical fiber production method includes a drawing process (PI) of drawing an optical fiber and a slow cooling process (P3) of slowly cooling the optical fiber. In the slow cooling process (P3), the optical fiber is passed through annealing furnaces (121), where the preset temperatures of the furnaces are controlled to keep the difference between the temperature of the optical fiber and the fictive temperature of the core within limits. Rayleigh transmission losses are reduced.