Undoped Fiber Optic Sensor for Harsh Environment Parameter Detection
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Solution Overview
Problem
Conventional fiber Bragg grating sensors face limitations in harsh environments due to thermal instability, dopant diffusion, and radiation-induced degradation, restricting their operation to temperatures below 80°C and making them unreliable for detecting multiple parameters like temperature, strain, and vibration.
Innovation Solution
A fiber optic sensor with a periodic or quasiperiodic modulated microcrystalline and rigid silicon dioxide tetrahedral grating structure, fabricated using high power femtosecond lasers and phase mask techniques, which enhances thermal stability and resistance to radiation, allowing simultaneous detection of multiple parameters up to 800°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional fiber Bragg grating sensors use doped photosensitive single-mode fiber core with Germanium oxides or co-dopants, then the sensors can measure parameters like strain, seismic vibrations, pressure, flow rate and temperature, but the dopants cause thermal variation of conductivity leading to degradation of refractive index modulation and limit operational temperature to below 80°C
Solution Approach 1:
The patent removes the dopant elements (Germanium oxides, boron, fluorine, phosphors, erbium) from the fiber core composition that cause thermal instability. By extracting these harmful dopants, the sensor achieves thermal stability above 80°C while maintaining the ability to measure multiple parameters through the undoped photosensitive fiber core
Solution Approach 2:
The patent changes the fundamental material parameter of the fiber core from doped to undoped photosensitive single-mode fiber. This parameter change eliminates the impurity energy levels and thermal conductivity variations caused by dopants, enabling reliable operation at temperatures above 80°C while preserving the grating's ability to sense multiple physical parameters
2Stability of the object's composition
If thermal post-treatment process is used to stabilize the fiber grating's refractive index modulation amplitude, then some stability is achieved, but the sensors still have low reliability while operating above the annealing temperature
Solution Approach 1:
The patent applies a preliminary thermal treatment process during manufacturing to create the grating structure in the undoped fiber core, eliminating the need for subsequent thermal post-treatment that causes instability. The grating is formed before the fiber is deployed in high-temperature environments, so no additional thermal processing is needed during operation, achieving both stability and reliability above annealing temperatures
3Adaptability or versatility
If high-energy radiations like gamma-ray and neutrons are present in nuclear reactor environments, then dopant diffusion and formation of color centers occur, but this leads to degradation of fiber grating structure and refractive index modulation
Solution Approach 1:
The patent removes dopants from the fiber core that are susceptible to radiation-induced diffusion and color center formation. By using undoped photosensitive fiber core, the sensor eliminates the material basis for radiation degradation, maintaining grating structure integrity and refractive index modulation even in high-radiation nuclear reactor environments
4Adaptability or versatility
If piezoelectric-based or magnetostrictive-based sensors are used for detecting strain and seismic signals in harsh environments, then detection capability is provided, but they are limited to low-temperature applications and suffer from electromagnetic interference and radiation degradation
Solution Approach 1:
The patent replaces piezoelectric and magnetostrictive sensing mechanisms with optical sensing based on light interaction with the fiber core. The photosensitive fiber core detects strain and seismic signals through optical property changes (refractive index modulation) rather than mechanical or magnetic effects, eliminating susceptibility to electromagnetic interference and radiation while enabling 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 solution provides a highly stable and reliable fiber optic sensor capable of detecting temperature, strain, and vibration in extreme conditions, with reduced thermal sensitivity and power loss drifting, enabling effective structural health monitoring in harsh environments.
Implementation Method 1
a fiber core having a plurality of Bragg grating elements wherein, the grating elements comprise a periodic or a quasiperiodic modulated microcrystalline and rigid silicon dioxide tetrahedral structure
Data Source
AI summary
A fiber optic sensor is provided. The fiber optic sensor includes a fiber core having a plurality of Bragg grating elements wherein, the grating elements comprise a periodic or a quasiperiodic modulated microcrystalline and rigid silicon dioxide tetrahedral structure and a cladding disposed about the fiber core.