Optical Fiber Characterization Using Shaped ASE Nonlinear Skirts
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Solution Overview
Problem
Current methods for characterizing optical fiber nonlinearity and dispersion are limited by the use of single polarization Continuous Wave signals, which fail to accurately measure Polarization Dependent Gain, Differential Group Delay, and Polarization Mode Dispersion, especially in multi-segment/mixed fiber spans with unknown lumped losses, leading to inaccurate modeling and performance optimization.
Innovation Solution
The system employs a processor coupled with an Amplified Spontaneous Emission (ASE) source and an optical receiver to transmit shaped ASE signals, characterizing optical fibers based on nonlinear skirts and center dip depth in the received spectrum, allowing for the determination of Group Velocity Dispersion and nonlinear coefficients, even in multi-segment/mixed fiber spans with unknown lumped losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If Continuous Wave (CW) signals are used for dispersion and nonlinearity measurement, then the measurement setup is simple, but the measurement accuracy deteriorates due to single polarization and inability to measure PDG, DGD, and PMD
Solution Approach 1:
The patent changes the signal type from Continuous Wave (CW) to Amplified Spontaneous Emission (ASE) signals. ASE signals have different polarization characteristics that enable measurement of PDG, DGD, and PMD while maintaining measurement capability. This parameter change resolves the contradiction by improving measurement accuracy without significantly increasing setup complexity.
2Device complexity
If two-wavelength dispersion measurement is used, then the measurement method is simple, but the measurement accuracy deteriorates as it only measures average dispersion at 1568nm rather than across the entire signal band
Solution Approach 1:
The patent uses ASE signals that sweep across multiple wavelengths continuously. This periodic action allows measurement of dispersion characteristics across the entire signal band rather than at a single average wavelength, resolving the contradiction by improving measurement accuracy while keeping the method relatively simple.
3Ease of operation
If traditional fiber characterization methods are used, then the measurement process is straightforward for homogeneous fiber, but the measurement accuracy deteriorates when dealing with multi-segment/mixed fiber spans with unknown lumped losses
Solution Approach 1:
The patent introduces ASE signals as an intermediary measurement tool that can penetrate through multi-segment/mixed fiber spans with unknown lumped losses. The ASE signal interacts with the fiber nonlinearity in a way that allows characterization of the entire span as an effective span, resolving the contradiction by improving measurement accuracy while maintaining operational simplicity.
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 provides accurate characterization of optical fibers, enabling effective modeling and optimization of link performance, simplifying fiber type identification, and improving transmission capacity and reliability by treating concatenated fibers as a single effective span.
Implementation Method 1
a processor coupled with an Amplified Spontaneous Emission (ASE) source and an optical receiver to transmit shaped ASE signals
Implementation Method 2
signal transmission performance is significantly impacted by optical fiber dispersion and nonlinearity
Implementation Method 3
characterizing the optical fiber based in part on one or more of a nonlinear skirt and a center dip depth in the received spectrum
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
Systems and methods include causing transmission of one or more shaped Amplified Spontaneous Emission (ASE) signals, from an ASE source (70), on an optical fiber (58, 60); obtaining received spectrum of the one or more shaped ASE signals from an optical receiver (68) connected to the optical fiber (58, 60); and characterizing the optical fiber (58, 60) based in part on one or more of a nonlinear skirt and a center dip depth in the received spectrum of the one or more shaped ASE signals. The one or more shaped ASE signals can be formed by the ASE source (70) communicatively coupled to a Wavelength Selective Switch (WSS) (62) that is configured to shape ASE from the ASE source to form the one or more shaped ASE signals with one or two or multiple peaks and with associated frequency.