Wavelength Division Multiplexer for Optical Fiber Sensor Interference
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Solution Overview
Problem
Backscattered light in optical fiber sensors interferes with the accuracy of disturbance location measurements, particularly in long-distance monitoring systems, as it cannot be effectively eliminated by conventional methods like optical filtering, leading to signal distortion and reduced system performance.
Innovation Solution
The implementation of wavelength division multiplexing (WDM) technology at the end of the sensing optical fiber to separate and extract a pure interference signal from scattered light, using two distinct wavelengths to isolate the effective signal component and remove interference caused by backscattered light, without requiring active devices that need power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If optical filtering is used to eliminate backscattered light, then signal purity is improved, but measurement precision deteriorates because Rayleigh scattering interference cannot be effectively filtered
Solution Approach 1:
The patent changes the wavelength parameter of light to eliminate backscattered light interference. By using a wavelength division multiplexer to separate the working wavelength (e.g., 1550nm) from the scattering wavelength (e.g., 1310nm), the system effectively removes Rayleigh scattering interference without affecting the measurement of disturbance locations. This parameter-based separation resolves the contradiction by selectively filtering based on wavelength characteristics rather than attempting to filter all scattered light.
2Measurement precision
If wavelength division multiplexing is implemented, then backscattered light elimination is improved, but device complexity increases due to additional components
Solution Approach 1:
The wavelength division multiplexer serves multiple functions simultaneously: it acts as a filter to separate working wavelength from scattering wavelength, serves as a signal routing component, and enables wavelength-based identification of interference sources. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving effective backscattered light elimination.
3Ease of operation
If conventional single core feedback structure is used, then ease of operation is improved, but reliability deteriorates due to light diffusion and reflection interference
Solution Approach 1:
The patent applies local quality by introducing wavelength-specific processing at critical points in the optical path. The wavelength division multiplexer is placed at the location where backscattered light enters the interference optical path, providing localized wavelength-based filtering. This allows the rest of the system to maintain its simple single-core feedback structure while locally addressing the reliability issue through wavelength discrimination.
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 method effectively eliminates the impact of backscattered light, enhancing the accuracy and adaptability of optical fiber sensing systems, allowing for longer measurement distances and easier implementation, especially in scenarios where powering active devices is challenging.
Implementation Method 1
using wavelength division multiplexing (WDM) technology at the end of the sensing optical fiber to separate and extract a pure interference signal from scattered light
Implementation Method 2
Optical fiber sensing technology is often used in large-scale, long-distance monitoring
Implementation Method 3
a feedback device, such as a mirror, is at an end of the fiber constituting an interference optical path
Implementation Method 4
The two optical paths join at the coupler 3 again and generate interference
Data Source
AI summary
A method using wavelength division multiplexing for reducing light diffusion and light reflection interference in an interference path, comprising: connecting a wavelength division multiplexer (10) serially at an end of a sensing optical fiber (6); using the wavelength division multiplexer (10) to extract a wavelength component from a working path for measuring an interfering signal caused by light diffusion and light reflection; using the signal as a reference to extract an effective signal component that has been interfered by light diffusion and light reflection, and obtaining a pure effective signal. Because the device connected at the end of the sensing optical fiber (6) is passive and requires no power, the system is easy to implement and is particularly suitable for situations in which power provision is difficult at the end of the sensing optical fiber (6). The method is suitable for long distance pipeline monitoring and a wide-range optical of fiber perimeter security. Also provided is a system using wavelength division multiplexing for reducing light diffusion and light reflection interference in an interference path.