Optical Power Distribution Estimation With Dispersion-Split Correlation
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Solution Overview
Problem
Conventional optical power distribution estimation methods using correlation techniques suffer from power offset issues, leading to inaccurate power level estimation and reduced estimation accuracy due to noise amplification, especially in digital coherent optical transmission systems.
Innovation Solution
The proposed method involves applying partial and residual wavelength dispersion to optical signals using Taylor-expanded linear terms for phase rotation, followed by nonlinear operations and correlation calculations to estimate optical power distribution accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional correlation method is used for optical power distribution estimation, then the estimation process can be performed digitally on reception side, but power offset issues occur leading to inaccurate power level estimation
Solution Approach 1:
The patent extracts and removes the power offset component from the correlation calculation process. By identifying the offset as a separate erroneous element and eliminating it through differential correlation or offset cancellation techniques, the method recovers the true optical power distribution without the contaminating offset effect.
Solution Approach 2:
The patent applies partial wavelength dispersion compensation at different stages of the correlation process. By applying dispersion compensation partially at the transmission side and partially at the reception side, or by adjusting the degree of compensation, the method optimizes the correlation accuracy while avoiding over-compensation that could introduce new errors.
2Extent of automation
If conventional correlation method is used for optical power distribution estimation, then digital signal processing can be performed on reception signal, but noise amplification occurs reducing estimation accuracy
Solution Approach 1:
The patent performs preliminary wavelength dispersion compensation on the transmitted signal before correlation processing. By pre-compensating the reference signal with the same dispersion characteristics that will affect the received signal, the method ensures that the correlation operation occurs between properly matched signals, preventing noise amplification that would otherwise occur from mismatched dispersion effects.
Solution Approach 2:
The patent introduces an intermediate reference signal that has been processed with known dispersion characteristics. This intermediate signal serves as a mediator between the transmitted signal and the received signal, allowing the correlation process to accurately measure power distribution without directly comparing signals that have undergone different uncontrolled dispersion effects.
3Measurement precision
If direct measurement on each optical node or optical fiber is performed using analog measuring instrument, then accurate characteristics can be obtained, but equipment cost and operating cost increase
Solution Approach 1:
The patent creates a digital copy of the transmitted signal at the reception side and processes this copy through correlation with the actual received signal. This digital copying approach replaces the need for physical analog measurement instruments at multiple locations, allowing accurate power distribution measurement through signal processing alone, thereby reducing equipment costs while maintaining measurement precision.
Solution Approach 2:
The patent replaces physical analog measurement instruments with digital signal processing methods. By substituting mechanical/optical measurement devices with computational correlation techniques, the system achieves the same measurement functionality without the associated hardware costs, complexity, and operational requirements of analog instruments.
Data Source
AI summary
An optical power distribution estimation device includes: a partial wavelength dispersion application unit that applies, to a signal, partial wavelength dispersion corresponding to a distance from an optical transmission device to an optical power measurement position; a nonlinear operation unit that performs, on the signal to which the partial wavelength dispersion has been applied, nonlinear operation using a linear term obtained by Taylor-expanding a mathematical expression used for phase rotation; a residual dispersion application unit that applies residual wavelength dispersion corresponding to a distance from the optical power measurement position to an optical reception device to the signal subjected to the nonlinear operation by the nonlinear operation unit; and a correlation calculation unit that estimates an optical power distribution of an optical transmission line by obtaining, for each optical power measurement position, a correlation between the signal to which the residual wavelength dispersion has been applied and a reception signal based on an optical signal transmitted from the optical transmission device and received via the optical transmission line.