Double Clad Optical Fibre for Simultaneous Sensing
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Solution Overview
Problem
Existing distributed optical fibre sensing technologies face challenges in simultaneously measuring temperature, strain, and vibration with high sensitivity and accuracy over extended lengths, particularly due to limitations in signal strength and interference between different sensing techniques, and the need for multiple fibre types.
Innovation Solution
A distributed optical fibre sensing system utilizing a double clad fibre with both single mode and multimode waveguides, allowing for simultaneous implementation of Rayleigh, Brillouin, and Raman scattering techniques, along with an optical amplifier section to enhance signal strength and reduce interference, enabling the use of a single fibre for multiple sensing operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple separate sensing techniques are used to measure temperature, strain and vibration, then measurement precision is improved, but device complexity increases due to needing multiple fibres and interrogators
Solution Approach 1:
The patent combines multiple sensing techniques (Rayleigh, Brillouin, and Raman scattering) into a single optical fibre by utilizing both single-mode and multi-mode waveguides within the same fibre structure. This merging approach allows simultaneous measurement of temperature, strain, and vibration without requiring separate fibres for each technique, thereby reducing device complexity while maintaining measurement precision
Solution Approach 2:
The optical fibre is designed with dual waveguide capabilities (single-mode and multi-mode) that enable it to perform multiple sensing functions simultaneously. The single-mode waveguide supports Rayleigh and Brillouin scattering for strain and vibration detection, while the multi-mode waveguide enables Raman scattering for temperature measurement, making the fibre a universal sensing platform
2Adaptability or versatility
If different sensing techniques are implemented simultaneously, then measurement capability is improved, but interference between techniques increases
Solution Approach 1:
The optical fibre is segmented into distinct waveguide modes (single-mode and multi-mode) that are spatially separated within the fibre structure. This segmentation allows different scattering techniques to operate in separate waveguide channels, reducing mutual interference while enabling simultaneous measurement of multiple parameters
Solution Approach 2:
The patent uses the waveguide structure itself as an intermediary that separates and manages different scattering processes. By directing different wavelengths and modes through appropriate waveguides, the system minimizes cross-talk and interference between Rayleigh, Brillouin, and Raman scattering techniques
3Measurement precision
If high probe light power is used to improve signal strength, then sensitivity is improved, but optical damage at connectors increases
Solution Approach 1:
The patent transitions from single-mode to multi-mode waveguide operation in certain sections, effectively adding a spatial dimension (mode field area) to the system. This dimensional change allows the same optical power to be distributed over a larger area, reducing power density at connectors and minimizing optical damage while maintaining sufficient signal strength for sensitive measurements
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 enables simultaneous and accurate measurement of temperature, strain, and vibration along extended lengths with improved sensitivity and range, reducing the need for multiple fibres and minimizing interference, while avoiding optical damage at connectors.
Implementation Method 1
an optical amplifier section between the first and second sections, the optical amplifier amplifying the probe light using pump light
Implementation Method 2
analysis of Rayleigh scattering which involves no frequency shift of the probe light
Implementation Method 3
analysis of the Brillouin scattered spectrum
Implementation Method 4
analysis of the Raman scattered spectrum
Data Source
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AI summary
There is disclosed a distributed optical fibre sensing system in which the sensor fibre comprises at least first and second waveguides used for separate sensing operations. The sensor fibre may be, for example, a double clad fibre having a monomode core and a multimode inner cladding.