Multi-Wavelength DAS Interrogator for Long-Distance Span Sensing
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Solution Overview
Problem
Conventional distributed acoustic sensing (DAS) systems require multiple interrogator units at different wavelengths to sense multiple spans, adding complexity and cost, and are limited to sensing distances of approximately 50-150 km, with leading fiber spans not being sensed due to Rayleigh backscattering filtering.
Innovation Solution
A single DAS interrogator unit with multiple wavelength/multiple frequency components is used to transmit and receive signals across multiple spans, reducing complexity and cost by eliminating the need for synchronized circuits and extending sensing distances up to 10,000 km.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple interrogator units operating at different wavelengths are used to sense different portions of optical fiber, then sensing coverage is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple wavelength components into a single interrogator unit. The single unit integrates multiple laser sources operating at different wavelengths, allowing it to sense multiple spans of optical fiber simultaneously, thereby reducing the need for multiple separate interrogator units while maintaining extended sensing coverage.
Solution Approach 2:
The single DAS interrogator unit is designed with multi-functionality to perform sensing across multiple spans using different wavelengths. It can operate at multiple wavelengths (e.g., C-band and L-band) to sense different portions of the optical fiber, making one device capable of what previously required multiple specialized devices.
2Length of stationary object
If multiple interrogator units are deployed to extend sensing distance, then sensing distance is improved, but structural complexity increases
Solution Approach 1:
The patent merges multiple wavelength components into a single integrated interrogator unit that can sense distances up to 10,000 km. By combining multiple laser sources and signal processing capabilities in one unit, the system extends sensing distance without requiring multiple distributed interrogator units, thereby reducing structural complexity.
3Device complexity
If conventional DAS systems with limited wavelength components are used, then device simplicity is maintained, but sensing distance is limited to 50-150 km
Solution Approach 1:
The patent changes the wavelength parameters by incorporating multiple wavelength components (e.g., C-band and L-band lasers) into a single interrogator unit. This parameter expansion allows the system to extend sensing distance from 50-150 km to up to 10,000 km while maintaining relative device simplicity through integration.
4Adaptability or versatility
If multiple optical amplifier pairs are disposed along the measurement path, then sensing capability is improved, but error rate increases
Solution Approach 1:
The single multi-wavelength interrogator unit acts as an intermediary that coordinates sensing across multiple optical amplifier pairs. By using multiple wavelength components, the system can sense different spans between amplifiers, reducing the error rate associated with disrupting elements while maintaining enhanced sensing capability.
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 system efficiently monitors long distances with reduced complexity and cost, enabling effective detection of disturbances and seismic activities in subsea environments by using a single DAS transmitter and receiver configuration.
Implementation Method 1
the DAS system may be based on Rayleigh backscattering (otherwise referred to as a Rayleigh-scattering-based DAS system). In this system, a coherent laser pulse may be sent along an optical fiber, and scattering sites within the optical fiber may cause the fiber to act as a distributed interferometer
Data Source
AI summary
An optical communication system and a method. The system includes a distributed acoustic sensing (DAS) interrogation unit. The DAS interrogation unit is configured to generate one or more optical signals for determining a status of one or more portions of an optical communication path, modulate one or more optical signals using one or more measurement pulses and generate one or more modulated optical signals, and transmit one or more modulated optical signals to the one or more portions of the optical communication path. The status of one or more portions of the optical communication path is determined based on one or more reflected signals reflected by one or more portions of the optical communication path in response to one or more modulated optical signals.