Optical Power Control Device for WDM Nonlinear SNR Estimation
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Solution Overview
Problem
Conventional techniques for optical power control in WDM transmission systems fail to accurately estimate nonlinear SNR, leading to uneven GSNR across wavelength bands, especially in multiband systems like C+L band transmission.
Innovation Solution
An optical power control device with a controller that obtains received waveforms of WDM signals, calculates the power profile along the transmission path, and estimates nonlinear SNR based on this profile, thereby correcting nonlinear SNR variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional optical power control techniques are used to suppress variation in optical power and OSNR, then transmission characteristics are improved, but nonlinear SNR estimation becomes inaccurate leading to uneven GSNR across wavelength bands
Solution Approach 1:
The patent replaces conventional mechanical/optical measurement methods with electrical signal processing. Specifically, it uses received waveform data and applies Fast Fourier Transform (FFT) to calculate power profiles and nonlinear SNR in the electrical domain, substituting traditional optical power meters and manual measurement procedures. This enables accurate nonlinear SNR estimation across all wavelength channels simultaneously.
Solution Approach 2:
The patent introduces an intermediary calculation process using FFT to transform received waveform signals into frequency domain representations. This intermediary step allows extraction of power profiles at different frequency components, which then enables accurate calculation of nonlinear SNR. The intermediary mathematical transformation bridges the gap between raw received signals and meaningful SNR metrics.
2Productivity
If wavelength band is expanded from C band to C+L band to increase capacity, then transmission capacity is improved, but GSNR uniformity deteriorates due to nonlinear noise variations
Solution Approach 1:
The patent segments the wide C+L band into individual wavelength channels and calculates power profiles and nonlinear SNR for each channel separately using FFT analysis. This segmentation allows identification of specific channels with degraded GSNR due to nonlinear effects, enabling targeted power adjustments for each wavelength rather than uniform control across the entire band.
Solution Approach 2:
The patent implements dynamic power control by continuously monitoring received waveforms and calculating real-time power profiles and nonlinear SNR values. The system dynamically adjusts transmitter power levels based on calculated metrics, adapting to changing transmission conditions across different wavelength channels to maintain GSNR uniformity throughout the C+L band.
3Measurement precision
If received waveform analysis is performed to calculate power profile and nonlinear SNR, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent implements self-service by using the received waveform data itself to calculate the power profile and nonlinear SNR. The system processes its own received signals through FFT analysis, eliminating the need for separate measurement devices or external calibration equipment. This self-contained approach reduces overall system complexity while maintaining high measurement precision.
Solution Approach 2:
The patent makes the controller multi-functional by combining received waveform analysis, FFT processing, power profile calculation, and nonlinear SNR estimation into a single integrated control device. This universal controller performs multiple functions that would traditionally require separate instruments, reducing device complexity while achieving accurate measurements through sophisticated signal processing.
Data Source
AI summary
An optical power control device includes a controller configured to: obtain a received waveform of a WDM optical signal transmitted between a plurality of transmission devices via a transmission path, and calculate a power profile of a distance direction of the transmission path based on the received waveform; and calculate a nonlinear SNR of the transmission path based on the power profile.