Distributed Fibre Optic Sensing for Birefringence Event Detection
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Solution Overview
Problem
Conventional distributed fibre optic sensing (DFOS) systems struggle to distinguish between birefringence events caused by physical handling of optical fibres and other noise sources like acoustic disturbances and weight-induced strain, leading to network errors and outages.
Innovation Solution
A DFOS method and system that utilizes distributed polarisation sensing (DPS) to detect and isolate birefringence events by processing backscattered optical signals for polarisation state changes, enabling the detection of physical handling such as moving, pulling, or twisting of optical fibres, and determining network errors or outages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional DFOS systems detect all backscattered optical signals, then they can capture all events including birefringence events, but they cannot distinguish birefringence events from noise sources like acoustic disturbances and weight-induced strain
Solution Approach 1:
The patent segments the detection process into two independent channels: a first channel that detects all backscattered optical signals for comprehensive event capture, and a second channel that selectively detects only birefringence events through polarisation state analysis. This segmentation allows the system to maintain high sensitivity while achieving precise event discrimination by comparing results from both channels.
Solution Approach 2:
The patent introduces an optical reference signal as an intermediary element that combines with backscattered optical signals to enable polarisation state detection. This intermediary reference signal facilitates the extraction of birefringence information without interfering with the primary detection channel, thereby improving event discrimination accuracy while maintaining signal integrity.
2Reliability
If DFOS systems increase detection sensitivity to capture subtle birefringence events, then they can detect physical handling of fibres, but they also amplify detection of noise sources leading to false alarms
Solution Approach 1:
The patent divides the detection system into two independent channels with different sensitivity profiles. The first channel operates at high sensitivity to detect all events including subtle birefringence events caused by physical fibre handling. The second channel uses polarisation state analysis to selectively detect birefringence events while filtering out acoustic and weight-induced noise. This segmentation enables high reliability detection without being overwhelmed by noise.
Solution Approach 2:
The patent applies different detection qualities to different event types by using polarisation state analysis specifically for birefringence event detection. The system tailors the detection approach to the specific characteristics of birefringence events, using polarisation sensitivity only where needed for identifying physical fibre handling, while relying on the first channel for general event detection. This local quality approach improves reliability for target events without amplifying noise across all detection channels.
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
Enhances the ability to promptly diagnose and mitigate network errors, flap events, and outages by improving signal-to-noise ratio and accurately locating birefringence events in fibre-optic communications networks.
Implementation Method 1
receiving backscattered optical signals in a distributed manner along the at least one optical fibre
Implementation Method 2
determining at least one birefringence event based on the at least one polarisation state change
Implementation Method 3
the at least one birefringence event is caused by anisotropic stress on the at least one optical fibre
Data Source
AI summary
A distributed fibre optic sensing (DFOS) method is disclosed. The method includes (a) repeatedly transmitting interrogating optical signals into at least one optical fibre: (b) receiving backscattered optical signals in a distributed manner along the at least one optical fibre: (c) combining the backscattered optical signals and an optical reference signal: (d) processing the combined signals to determine at least one polarisation state change of the backscattered optical signals along the at least one optical fibre; and (e) determining at least one birefringence event based on the at least one polarisation state change