Optical Receiver Polarization Monitoring via Zero-Frequency Response Matrices
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Solution Overview
Problem
Current methods for monitoring polarization state changes in optical links are either costly and slow due to hardware requirements or fail to accurately reflect changes in specific segments of the optical link, as they are influenced by the input signal's polarization state.
Innovation Solution
An apparatus and method that combine zero-frequency response matrices and phase information from signals at two moments to determine a change matrix, allowing for real-time monitoring of polarization state changes in the optical link without additional hardware, thereby simplifying the structure and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hardware-based methods (DC laser and commercial polarimeter) are used to monitor polarization state changes, then measurement capability is provided, but device complexity and cost increase
Solution Approach 1:
The patent replaces hardware-based polarization monitoring (using DC laser and commercial polarimeter) with a digital signal processing approach. The processor extracts equalization coefficients from received signals, constructs channel response matrices, and calculates polarization state changes through mathematical operations, eliminating the need for additional physical monitoring hardware.
Solution Approach 2:
The patent creates a mathematical model (channel response matrix) that replicates the function of physical polarization monitoring. By processing the received signal through digital equalization and matrix operations, the system generates a virtual representation of polarization state changes without requiring physical polarimeters or additional optical components.
2Speed
If digital signal processing is used to track polarization state changes, then monitoring speed increases, but accuracy of reflecting specific segment changes decreases
Solution Approach 1:
The patent extracts the polarization state change information from the overall channel response by using a reference matrix (representing the input signal's polarization characteristics) to normalize and isolate the changes caused by the optical link. This extraction process separates the specific segment changes from the total response, enabling accurate monitoring of the optical link's polarization changes while maintaining high-speed digital processing.
3Productivity
If conventional digital signal processing methods are used, then processing speed is improved, but additional hardware is required
Solution Approach 1:
The patent makes the existing optical receiver perform multiple functions: it simultaneously receives and demodulates optical signals while also monitoring polarization state changes. The processor uses the same received signal for both standard communication functions and polarization analysis, constructing channel response matrices from the equalization coefficients already obtained during normal signal processing, thereby eliminating dedicated monitoring hardware.
Data Source
AI summary
An apparatus and method for monitoring a change of a polarization state resulted from an optical link and optical receiver is provided. By combining zero-frequency response matrices and phase information on the received signal at two moments, a change matrix of the zero-frequency channel response matrices at the two moments is obtained, and a parameter characterizing a polarization state change induced by the optical link is determined according to the change matrix, which may dynamically monitor in real-time manner the polarization state change induced by the optical link, irrelevant to the polarization state of an input signal of the optical link. Due to the combination of the zero frequency response matrices and the phase information, response of the optical link may be completely reflected, for more accurate monitoring the polarization state. In addition, there is no need to add additional hardware and controls, thereby simplifying the structure and saving cost.