VAD Optical Fiber Base Material Deposition for Stable Characteristics
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Solution Overview
Problem
Existing VAD methods for manufacturing optical fiber base materials suffer from significant fluctuations in optical characteristics along the longitudinal direction due to variations in pull-up speed and raw material gas flow rates, affecting parameters like cutoff wavelength and mode field diameter.
Innovation Solution
A method involving real-time detection of the tip position of the porous glass base material during deposition, setting a target pull-up speed for each deposition time, and adjusting the raw material gas flow rate to stabilize the pull-up speed, with gradual changes in the early stage of deposition, followed by maintaining a constant speed in the steady state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pull-up speed is adjusted to maintain a constant tip position during deposition, then the optical characteristics are stabilized, but the deposition time increases due to gradual speed changes in the early stage
Solution Approach 1:
The patent applies preliminary action by implementing a gradual pull-up speed increase during the early stage of deposition (first 300-500 minutes) before transitioning to constant speed. This preliminary speed adjustment period allows the deposition process to stabilize, ensuring optimal optical characteristics in the final product while maintaining overall efficiency through the subsequent constant speed operation.
2Manufacturing precision
If the raw material gas flow rate is successively adjusted to achieve target pull-up speed, then the deposition control precision is improved, but the system complexity increases
Solution Approach 1:
The patent implements feedback control by continuously monitoring the actual pull-up speed and comparing it with the target pull-up speed, then successively adjusting the raw material gas flow rate based on this comparison. This closed-loop feedback mechanism ensures precise control of the deposition process while maintaining manageable system complexity through automated control algorithms.
3Manufacturing precision
If the pull-up speed is gradually changed in the early stage, then the characteristic fluctuation is suppressed, but the productivity decreases compared to constant high speed
Solution Approach 1:
The patent applies segmentation by dividing the deposition process into two distinct stages: an early stage (first 300-500 minutes) with gradual pull-up speed increase to suppress characteristic fluctuations, and a steady state stage with constant pull-up speed to maximize productivity. This temporal segmentation allows the system to optimize for precision during the critical early phase while recovering efficiency in the subsequent phase.
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 a porous glass base material with suppressed longitudinal characteristic fluctuations, ensuring consistent optical properties by stabilizing the deposition process.
Implementation Method 1
combustible and auxiliary gases are fed into a burner to generate an oxyhydrogen flame
Implementation Method 2
raw material gases such as silicon tetrachloride or germanium tetrachloride are introduced into this flame to produce glass particles through a hydrolysis reaction
Implementation Method 3
The generated glass particles are deposited in the axial direction of a starting member attached to a shaft that rises while rotating, thereby growing the glass particle deposit into a cylindrical shape
Implementation Method 4
The obtained porous glass base material is then dehydrated and vitrified into transparent glass in a heating furnace
Data Source
AI summary
A manufacturing method of porous glass base material for optical fiber with suppressed characteristic fluctuation in the longitudinal direction is provided. A manufacturing method of optical fiber base material by the VAD method includes: detecting a tip position of a porous glass base material during deposition; controlling the pull-up speed to keep the tip position constant; in an early stage of deposition, a target pull-up speed is set for each deposition time, and a raw material gas flow rate to the burner is adjusted and corrected at a predetermined correction interval to achieve the target pull-up speed, thereby depositing while gradually changing the pull-up speed until a predetermined time; in a steady state, the deposition is performed such that the pull-up speed is kept constant to form the porous glass base material; and the porous glass base material is dehydrated and vitrified into transparent glass in a heating furnace.