Optical Filter Fault Localization via Noise Density Comparison
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Solution Overview
Problem
In optical communication systems, localizing faulty wavelength selective switches (WSS) is challenging due to the difficulty in detecting spectrum narrowing and central wavelength shifts, especially without a large number of optical spectrum analyzers, which is costly and inefficient.
Innovation Solution
A method and system for optical filter fault localization using a link controller that determines accumulated noise density from amplified spontaneous emission (ASE) noise, comparing it with predicted noise densities to identify the faulty WSS, without the need for additional hardware like high-resolution optical spectrum analyzers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple optical spectrum analyzers are deployed at different locations in the transmission link to localize faulty filters, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the fault localization function from the traditional OSA hardware and implements it through digital signal processing techniques. By analyzing the optical signal characteristics (spectrum narrowing and central wavelength shift) at the receiver end and comparing them with predicted values from different WSS locations, the system determines the faulty filter location without requiring physical OSAs at multiple points along the transmission link.
Solution Approach 2:
The patent replaces the mechanical/optical measurement system (physical OSAs at multiple locations) with a digital processing system. The receiver DSP analyzes the optical signal spectrum, compares it with predicted spectra from simulated or stored WSS characteristics, and identifies the faulty filter location through computational methods rather than physical measurement instruments.
2Reliability
If multiple optical spectrum analyzers are deployed at different locations in the transmission link to localize faulty filters, then fault localization capability is improved, but loss of energy increases
Solution Approach 1:
The patent extracts the energy-intensive function of multiple physical OSAs and replaces it with low-power digital signal processing. The receiver end performs spectral analysis and fault localization computations using available computational resources, significantly reducing the energy consumption required for fault detection compared to deploying multiple high-power optical measurement instruments throughout the transmission link.
3Device complexity
If a simple system without multiple OSAs is used for fault localization, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent performs preliminary actions by pre-calculating and storing predicted optical signal characteristics (spectrum profiles) for each WSS location under normal operating conditions. These predicted values are stored in a database or lookup table at the receiver end, enabling rapid fault localization through comparison without requiring complex real-time simulations or multiple physical measurement systems.
Solution Approach 2:
The patent creates a virtual copy of the expected optical signal behavior at each WSS location through digital modeling and prediction. Instead of physically measuring at multiple locations with OSAs, the system generates simulated or predicted spectral signatures for each potential fault location and compares the actual received signal against these digital copies to identify mismatches indicating faulty WSS positions.
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
Enables efficient localization of faulty WSS in dense wavelength-division multiplexing (DWDM) optical links by correlating noise densities, allowing for accurate identification and potential rerouting to bypass the faulty component, thus maintaining communication integrity without the need for extensive hardware.
Implementation Method 1
amplified spontaneous emission (ASE) noise from each optical amplifier between the transmitter and the receiver may be added to the wavelength channel
Implementation Method 2
the ASE noise accumulated up to a location of the faulty WSS may be filtered out asymmetrically
Data Source
AI summary
The disclosed systems and methods for optical filter fault localization. The optical filter fault localization is based on: i) determining an accumulated noise density at frequencies where ASE noise is filtered out by a faulty optical filter in an optical signal; ii) comparing the accumulated noise density with predicted accumulated noise densities, the predicted accumulated noise densities representing noises predicted from a plurality of optical filters to a receiver; and iii) determining, based on the comparison of the accumulated noise density and the predicted accumulated noise densities, a location of the faulty optical filter.