Optical Network Device PDL Position Detection
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Solution Overview
Problem
Current methods for detecting polarization dependent loss (PDL) in optical transmission lines are inefficient, requiring dedicated test lights and disrupting communication services, and struggle to accurately determine the position of PDL along long transmission lines.
Innovation Solution
An optical network device that receives polarization multiplexed signals, separates and controls polarization components, calculates evaluation values at multiple positions, and determines the position of PDL by comparing variations in these values, allowing for continuous monitoring without disrupting service.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dedicated test light is used to measure PDL, then measurement accuracy is improved, but communication service continuity deteriorates
Solution Approach 1:
The patent combines the PDL measurement function with the normal communication signal transmission. Instead of using separate dedicated test lights, the system utilizes the existing polarization multiplexed communication signals to carry out both communication and PDL measurement simultaneously, eliminating service interruption while maintaining measurement capability
Solution Approach 2:
The communication signal serves dual purposes: it acts as both the data transmission carrier and the test signal for PDL measurement. By making the communication signal multi-functional, the system achieves continuous service operation while enabling ongoing PDL monitoring without requiring dedicated test equipment
2Measurement precision
If optical signals are tapped at multiple positions to detect PDL location, then position detection capability is improved, but time and effort required increases
Solution Approach 1:
The patent introduces an intermediary approach by using the polarization state information extracted from the received signal to infer PDL position. Instead of physically tapping signals at multiple points, the system uses polarization analysis at the receiver end to indirectly determine PDL location, significantly reducing time and effort while maintaining detection accuracy
Solution Approach 2:
The patent replaces the mechanical/physical approach of tapping optical signals at multiple positions with a signal processing approach. By substituting physical signal sampling with polarization state analysis and mathematical processing of the received signal, the system achieves position detection without the time-consuming physical tapping process
3Measurement precision
If polarization components are separated and controlled to calculate evaluation values, then PDL detection accuracy is improved, but device complexity increases
Solution Approach 1:
The system uses the received polarization multiplexed signal itself to perform PDL measurement without requiring external test signals or additional complex measurement equipment. The signal processing operations (polarization separation, coordinate transformation, evaluation value calculation) are performed using the existing signal structure, making the system self-sufficient and avoiding additional complexity
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 and accurate detection of PDL positions along optical transmission lines, reducing the time and effort required to identify issues and maintaining continuous communication.
Implementation Method 1
a coherent receiver separates a polarization multiplexed optical signal into a plurality of polarization components
Data Source
AI summary
An optical network device includes a receiver that receives a polarization multiplexed optical signal and a processor. The processor separates an electric field information signal indicating the polarization multiplexed optical signal into first and second polarization components orthogonal to each other, generates third and fourth polarization components by controlling the first and second polarization components, calculates an evaluation value corresponding to a power of the third or fourth polarization component for each of a plurality of positions on a transmission line, calculates a variation in the evaluation value for a control amount for each of the plurality of positions, and decides whether a first position is a position to be detected based on a result of comparing a variation in an evaluation value for the first position with a variation in an evaluation value for a second position adjacent to the first position.