Fiber Bragg Grating High-Temperature Stability via Band-Gap Engineering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fiber Bragg grating sensors exhibit thermal instability at elevated temperatures, with Type-I, Type-IIA, and Type-II gratings degrading or erasing within a few hours at temperatures above 500 K to 900 K, making them unsuitable for high-temperature sensing applications.
Innovation Solution
A method of fiber core material band-gap engineering is employed, involving doping with atoms to enhance photosensitivity, co-doping with ions to increase mean coordination number, and thermal annealing to widen the band gap, forming a thermally stabilized nanophase tetrahedral grating structure that maintains refractive index modulation and stability at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional UV inscribed FBG (Type-I, Type-IIA, or Type-II) is used, then the sensor can be fabricated with standard processes, but the grating erases or degrades within a few hours at temperatures above 500 K to 900 K
Solution Approach 1:
The patent applies parameter changes by modifying the fiber core material composition through doping with atoms (e.g., germanium, boron, phosphorous) and co-doping with ions to alter the photosensitivity and structural properties. Thermal annealing is used to widen the band gap and stabilize the grating structure, transforming the material parameters to achieve high-temperature stability up to 1000 K
Solution Approach 2:
The patent employs composite materials by creating a doped fiber core material that combines multiple dopants and co-dopants within the silica matrix. This composite structure with enhanced photosensitivity and crosslinked amorphous network provides superior thermal stability compared to conventional undoped or singly-doped fibers
2Manufacturing precision
If the fiber core material is heavily doped to enhance photosensitivity, then grating inscription becomes more effective, but the material may become less stable at high temperatures
Solution Approach 1:
The patent resolves this contradiction by carefully controlling dopant concentrations and types, using specific combinations of atoms and ions that provide optimal photosensitivity for grating inscription while maintaining high-temperature stability through band gap engineering and thermal annealing processes
Solution Approach 2:
The patent introduces thermal annealing as an intermediary process that transforms the doped fiber structure, widening the band gap and stabilizing the material. This intermediary treatment allows the heavily doped material to achieve both high photosensitivity for effective grating inscription and enhanced thermal stability for high-temperature operation
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 approach results in a highly thermal-stabilized fiber Bragg grating sensor capable of withstanding temperatures up to 1000 K, with reduced power loss and wavelength shift, maintaining reflectivity and accuracy in harsh environments.
Implementation Method 1
doping the fiber core material with one or more atoms for enhancing photosensitivity to the fiber material
Implementation Method 2
thermally annealing the fiber core material for widening the band gap of the fiber core material
Implementation Method 3
method of fiber core material band-gap engineering for artificially fiber material properties
Data Source
AI summary
A method of fiber core material band gap engineering for artificially modifying fiber material properties is provided. The method includes doping the fiber core material with one or more atoms for enhancing photosensitivity to the fiber material. The method also includes co-doping the fiber core material with one or more ions for enhancing an amorphous network crosslink mean coordination number. The method further includes thermally annealing the fiber core material for widening the band gap of the fiber core material.