Polarization Scattering Compensation in Optical Coherent Receivers
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Solution Overview
Problem
Current adaptive filters in optical coherent receivers struggle to track high-speed polarization state changes in optical communication systems, leading to signal crosstalk and decreased Signal-to-Noise Ratio (SNR) due to polarization scattering, which affects the performance of the receiver.
Innovation Solution
A polarization scattering compensation device that includes a time sequence alignment unit, a polarization scattering estimation unit, and a polarization scattering removal unit to align and estimate scattering coefficients, and subsequently remove polarization scattering between signals in two polarization states, thereby eliminating crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If adaptive filter is used for polarization demultiplexing, then polarization state tracking is achieved, but tracking speed is limited to KHz magnitude and cannot follow GHz magnitude polarization changes
Solution Approach 1:
The patent replaces the traditional adaptive filter (which uses feedback control mechanisms) with a direct polarization scattering compensation method. This substitution eliminates the speed limitation of feedback-based adaptive filters and enables direct tracking of GHz-magnitude polarization changes through mathematical compensation of scattering coefficients.
Solution Approach 2:
The patent changes the fundamental parameter being tracked from polarization state directly to polarization scattering coefficients. By estimating and compensating for scattering coefficients between polarization states, the system can track rapid polarization changes at GHz magnitudes without being constrained by the response speed of traditional adaptive filter feedback mechanisms.
2Manufacturing precision
If adaptive filter tracks polarization state changes, then signal equalization is achieved, but polarization scattering causes crosstalk between polarization states
Solution Approach 1:
The patent converts the harmful polarization scattering effect into a measurable parameter (scattering coefficient) that can be estimated and compensated. By treating the scattering between polarization states as a quantifiable phenomenon rather than an uncontrollable interference, the system can calculate compensation values and eliminate crosstalk, thereby improving signal separation accuracy.
Solution Approach 2:
The patent introduces polarization scattering coefficients as an intermediary parameter between the transmitted and received signals. These coefficients serve as a bridge that characterizes the scattering relationship between polarization states, enabling the receiver to compensate for scattering effects and achieve accurate signal separation despite polarization changes in the transmission medium.
3Reliability
If polarization scattering occurs, then Signal-to-Noise Ratio decreases, but the proposed compensation device can track and restore fast polarization changes
Solution Approach 1:
The patent performs preliminary estimation of polarization scattering coefficients before they cause significant signal degradation. By proactively calculating compensation values based on estimated scattering coefficients and applying them in advance, the system prevents SNR deterioration caused by rapid polarization changes rather than reacting after damage occurs.
Data Source
AI summary
Polarization scattering compensation device and method are disclosed. In the device, a time sequence alignment unit aligns time sequences of signals in the first and second polarization state transmitted simultaneously; a polarization scattering estimation unit estimates a scattering coefficient of a scattering by the signal in the first polarization state on the signal in the second polarization state, and a scattering coefficient of a scattering by the signal in the second polarization state on the signal in the first polarization state; and a polarization scattering removal unit removes the scattering by the signal in the first polarization state on the signal in the second polarization state, and the scattering by the signal in the second polarization state on the signal in the first polarization state, in accordance with the scattering coefficients.