FIR Filter Tap Control for Optical Phase Noise and Polarization
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Solution Overview
Problem
Optical phase noise and high-speed polarization fluctuations in coherent optical communication systems lead to bit errors, which existing methods struggle to accurately measure and compensate for, particularly due to the influence of 1/f noise and sudden phase variations.
Innovation Solution
A control device and method using digital signal processing with a finite impulse response filter to accurately evaluate and compensate for optical phase noise and polarization fluctuations by measuring differential phase and integrating polarization fluctuation detection, enabling real-time detection and compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional phase noise measurement methods are used, then measurement simplicity is maintained, but measurement precision deteriorates due to 1/f noise and sudden phase variations
Solution Approach 1:
The patent segments the phase noise measurement process into distinct components: a delay interferometer for differential phase measurement, a polarizing beam splitter for polarization component separation, and a photodetector for signal conversion. This segmentation allows each component to perform its specific function optimally, improving overall measurement precision while maintaining manageable system complexity through modular design.
Solution Approach 2:
The patent introduces a delay interferometer as an intermediary device that converts optical phase differences into intensity variations. This intermediary transformation enables accurate phase noise measurement by converting the难以直接测量的相位信息 into easily detectable intensity signals, thereby improving measurement precision without requiring direct phase detection capability.
2Reliability
If existing compensation methods are used, then system simplicity is maintained, but reliability deteriorates due to inability to compensate for high-speed polarization fluctuations
Solution Approach 1:
The patent implements feedback mechanisms where the measured differential phase and polarization fluctuation signals are continuously fed back to control devices (phase shifters and polarization controllers). This real-time feedback enables dynamic compensation of phase noise and polarization fluctuations, significantly improving system reliability and reducing bit error rates through continuous optimization.
Solution Approach 2:
The patent designs a compensation system that simultaneously handles multiple impairment types: phase noise compensation through phase shifters and polarization fluctuation compensation through polarization controllers. This multi-functional approach improves reliability by addressing various sources of degradation in a unified system, rather than requiring separate compensation mechanisms for each impairment type.
3Productivity
If real-time compensation is implemented, then operational efficiency is improved, but device complexity increases due to additional control mechanisms
Solution Approach 1:
The patent merges the measurement and compensation functions into an integrated system where the delay interferometer serves both as a measurement device for differential phase and as part of the compensation loop. This merging reduces overall device complexity by eliminating redundant components and enabling the same hardware to perform multiple functions in the signal processing chain.
Solution Approach 2:
The patent implements self-service mechanisms where the system automatically monitors its own performance through differential phase measurement and autonomously adjusts compensation parameters through feedback control. This self-service capability improves operational efficiency by eliminating the need for external manual intervention while maintaining manageable complexity through automated control algorithms.
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
Enhances the accuracy of phase noise and polarization fluctuation measurement, reducing bit errors and improving the operational efficiency and maintenance of optical transmission systems.
Implementation Method 1
an optical delay interferometer that measures a differential phase of input light
Implementation Method 2
an optical receiver that converts the output light of the optical delay interferometer into an electrical signal
Data Source
AI summary
A control device which controls an operation of a compensation device which compensates for birefringence and/or polarization mode dispersion, which is received by signal light having propagated through an optical transmission line, by digital signal processing using a finite impulse response filter includes: a detection signal reception unit which receives a detection signal which is a signal indicating a detection result of a detection device which optically detects polarization fluctuation in the optical transmission line; and a setting unit which decides a setting regarding an update frequency or an update interval of the number of taps of the finite impulse response filter or an update frequency or an update interval of a tap coefficient of the finite impulse response filter, based on the detection result of the detection device.