All-Optical OSNR Measurement Using Polarized Probe Signals
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Solution Overview
Problem
Current methods for characterizing optical fiber communication links, particularly submarine cables, are inadequate as they rely on expensive 'golden' coherent transceivers and fail to fully account for nonlinear and polarization effects, making them impractical and incomplete for transponder-agnostic measurements.
Innovation Solution
The use of a polarized probe signal and power loading light in the optical transmission channel, analyzed using a Varied-SOP polarization-resolved Optical Spectral Analyzer (VSOP-OSA), allows for accurate measurement of noise parameters like OSNRASE and OSNRNL independently of terminal equipment, enabling characterization of polarization effects such as DGD, PMD, and PDL.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If coherent transponder-based methods are used to measure GOSNR, then measurement capability is provided, but dependency on expensive golden transceivers increases and measurement repeatability deteriorates
Solution Approach 1:
The patent introduces an optical spectrum analyzer as an intermediary device to measure OSNR directly in the optical domain, bypassing the need for coherent transponders. This mediator enables GOSNR measurement through mathematical discrimination of signal and noise components in optical spectra, eliminating dependency on expensive golden transceivers while maintaining measurement repeatability across different commercial-grade transceiver implementations.
Solution Approach 2:
The patent replaces the electronic/coherent detection system with an optical measurement approach using an optical spectrum analyzer. By substituting the coherent transponder-based electronic measurement system with direct optical spectrum analysis and mathematical processing, the method achieves transponder-agnostic GOSNR measurement that is independent of transceiver implementation details.
2Device complexity
If traditional OSNR measurement methods are used, then simplicity is maintained, but inability to account for nonlinear and polarization effects increases
Solution Approach 1:
The patent extends traditional OSNR measurement by introducing multiple parameters including GOSNR (Generalized OSNR) that combines linear and nonlinear noise contributions, and by measuring OSNR across multiple polarization states. This parameter expansion allows comprehensive characterization of optical link performance including nonlinear and polarization effects while building upon the familiar optical spectrum analysis foundation.
Solution Approach 2:
The patent adds the polarization dimension to traditional OSNR measurement by acquiring optical spectra at multiple polarization states and performing mathematical discrimination. This dimensional extension transforms the measurement from a single scalar value to a comprehensive characterization that includes polarization-dependent effects, enabling accurate GOSNR measurement without requiring complex coherent detection systems.
3Measurement precision
If golden transceivers are used for back-to-back and end-to-end measurements, then measurement accuracy is improved, but cost and practicality deteriorate
Solution Approach 1:
The patent creates a transponder-agnostic measurement method that copies the essential measurement function without requiring the complex coherent transponder system. By using an optical spectrum analyzer to capture optical spectra and applying mathematical discrimination techniques, the method replicates GOSNR measurement capability using simple, commercially available equipment instead of expensive golden transceivers.
Solution Approach 2:
The patent replaces expensive, rare golden transceivers with inexpensive, commercially available optical spectrum analyzers and standard transceivers. This substitution uses cheap, readily available equipment to achieve the same measurement objectives, making the measurement process practical and repeatable in real-world deployment scenarios without requiring special test equipment.
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
This approach enables accurate, cost-effective, and transponder-agnostic characterization of optical fiber communication links, improving measurement accuracy and reducing dependency on specific transceiver implementations, facilitating pre-deployment assessments and supporting high-speed transponder validation.
Implementation Method 1
acquiring, for each of a number nSOP of varied state-of-polarization analysis conditions, at least one polarization-analyzed optical spectrum trace
Data Source
AI summary
There are herein provided methods and systems to characterize optical propagation characteristics of an optical fiber communication link (such as, e.g., a submarine line system), including ASE noise (such as traditional OSNRASE), non-linear noise (such as OSNRNL due to nonlinear distortions) and/or the GOSNR. The method uses a polarized probe signal in the optical transmission channel under test in order to probe the link under test, as well as power loading light in other optical transmission channels in order to activate non-linear effects. The propagated test signal is then analyzed under varied polarization conditions using a varied-SOP polarization-resolved optical spectrum analysis of the propagated probe signal.