Polarization Fluctuation Estimation in Optical Signals
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Solution Overview
Problem
Existing polarization multiplexing digital coherent methods struggle to accurately estimate polarization fluctuation speed, especially when signal quality is low or when the modulation method and symbol rate are unknown, and they are limited by the tracking ability of adaptive equalizers.
Innovation Solution
A polarization fluctuation estimation device and method that generates a single-polarization optical signal from a polarization-multiplexed optical signal, converts it into an electric signal, and estimates the polarization fluctuation speed based on this signal, independent of signal quality, using a combination of polarization de-multiplexing, photoelectric conversion, and estimation units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adaptive equalizer is used for polarization de-multiplexing, then polarization tracking can be achieved, but estimation fails when signal quality is low or modulation method is unknown
Solution Approach 1:
The invention separates polarization fluctuation estimation from the adaptive equalizer by extracting intensity fluctuation information from the received signal before demodulation. This segmentation allows estimation to be performed independently of signal quality and modulation method, while the adaptive equalizer continues to handle polarization tracking for demultiplexing.
2Measurement precision
If adaptive equalizer tracking is used, then polarization de-multiplexing performance is improved, but estimation cannot be performed when fluctuation speed exceeds tracking ability
Solution Approach 1:
The invention uses intensity fluctuation of the received optical signal as an intermediary to estimate polarization fluctuation speed. This intermediary approach bypasses the adaptive equalizer's tracking limitations, enabling estimation of high-speed polarization fluctuations that exceed the equalizer's tracking capability while maintaining accurate polarization de-multiplexing.
3Measurement precision
If demodulation is required for estimation, then accurate polarization state can be obtained, but estimation fails when received signal cannot be demodulated
Solution Approach 1:
The invention performs polarization fluctuation estimation by analyzing intensity fluctuation in the received signal before demodulation is attempted. This preliminary action allows estimation to be conducted on raw signals regardless of their quality or modulation type, ensuring estimation availability even when subsequent demodulation fails.
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 high-precision estimation of polarization fluctuation speed without relying on signal quality or the limitations of adaptive equalizers, allowing for improved performance in optical transmission systems.
Implementation Method 1
a photoelectric conversion means for converting the generated optical signal into an electric signal
Data Source
AI summary
In order to estimate a polarization fluctuation speed with high accuracy independently of the quality of a received signal, a polarization-fluctuation estimating device according to the present invention includes: a polarization de-multiplexing unit that generates a single-polarization optical signal from an input polarization-multiplexed optical signal; a photoelectric converting unit that converts the generated optical signal into an electrical signal; and an estimation unit that estimates the polarization fluctuation speed of the polarization-multiplexed optical signal in accordance with the electrical signal.