Swept Wavelength Laser Rayleigh Backscatter Reduction
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Solution Overview
Problem
Rayleigh backscatter limits the performance of wavelength division multiplexed fiber optic sensor networks by increasing noise and reducing the optical signal-to-noise ratio (OSNR), which restricts the reach and capacity of optical networks and makes it difficult to detect faults accurately.
Innovation Solution
The method involves modulating the intensity of a swept wavelength laser to limit its scan range to small spectral slices, serially stitching these slices across the fiber Bragg grating peak spectrum, and intentionally separating Rayleigh and FBG signals in time to reduce noise floor degradation and enhance fault detection capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a swept wavelength laser is used to illuminate the entire spectral range, then the measurement coverage is improved, but the Rayleigh backscatter noise increases and degrades the optical signal-to-noise ratio
Solution Approach 1:
The patent divides the full spectral range into multiple discrete wavelength channels or slices. Instead of illuminating the entire spectrum at once, the system sequentially or parallelly measures specific wavelength segments, thereby reducing the Rayleigh backscatter noise in each segment while maintaining comprehensive measurement coverage through aggregation of results across all segments.
Solution Approach 2:
The patent employs partial illumination by directing the laser to scan through only a subset of the total spectral range at any given time. This partial action approach reduces the accumulated Rayleigh noise while the system progressively covers the full range through multiple scans or parallel channels, achieving the necessary measurement coverage without the noise penalty of full-range simultaneous illumination.
2Adaptability or versatility
If the laser scan range is increased to cover more sensor wavelengths, then the sensing capacity is improved, but the Rayleigh backscatter accumulates and reduces measurement precision
Solution Approach 1:
The patent segments the spectral measurement into discrete wavelength channels or slices. Each segment is measured independently with reduced Rayleigh noise, and the results are aggregated to provide comprehensive sensing capacity across the full range. This segmentation maintains measurement precision by preventing noise accumulation in any single measurement interval.
Solution Approach 2:
The patent employs periodic or sequential scanning of the laser wavelength across defined segments. By periodically sweeping through specific wavelength ranges and aggregating data from multiple periods, the system achieves comprehensive sensing capacity while the periodic nature allows for noise reduction techniques such as averaging or filtering, thereby maintaining measurement precision.
3Power
If the laser intensity is increased to improve signal strength, then the optical signal strength is improved, but the Rayleigh backscatter noise increases proportionally
Solution Approach 1:
The patent segments the spectral measurement into discrete wavelength channels. By concentrating the laser intensity into narrower spectral slices rather than broadening it across the full range, the system maintains adequate signal strength for each segment while the segmented approach prevents Rayleigh noise from accumulating across the entire spectrum. The signal-to-noise ratio is preserved through this spectral segmentation strategy.
Solution Approach 2:
The patent applies local quality by concentrating optical energy into specific wavelength regions rather than distributing it uniformly across the full spectrum. Each local wavelength slice receives adequate intensity for strong signal detection, while the localized nature of the illumination minimizes the generation of Rayleigh backscatter in other regions. This local concentration strategy maintains signal strength without proportionally increasing overall noise.
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 optimizes the signal-to-noise ratio, reduces Rayleigh noise, and allows for more accurate fault location identification in fiber optic networks, meeting the measurement requirements of GPON demarcation architecture and extending monitoring coverage beyond traditional limitations.
Implementation Method 1
modulating the intensity of a swept wavelength laser
Implementation Method 2
modulating the intensity of a swept wavelength laser
Implementation Method 3
illuminating small (∼1 nm) spectral slices per scan of the swept wavelength laser, serially stitching these slices of fiber bragg grating (FBG) peak identified spectrum
Implementation Method 4
overcoming or otherwise reducing Rayleigh backscatter in wavelength division multiplexed fiber optic sensor systems
Data Source
AI summary
Systems, methods, and structures for overcoming Rayleigh backscatter in wavelength division multiplexed fiber optic systems and in particular fiber optic sensor systems along with method(s) for detecting faults in optical networks employing the intentional temporal separation of share wavelength noise and demarcation signals in conjunction with the use of accumulated Rayleigh noise signal(s) to detect a fault location.