Optical Channel Power Equalization for DWDM Stability
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Solution Overview
Problem
In optical DWDM systems, adding or removing signals on wavelength channel slots causes power changes to other channels due to transient and steady-state amplification effects, leading to slow channel slot add/delete processes and power instability.
Innovation Solution
Maintaining all channels in a fiberoptic transmission link with a nominal power by adding idle tones to empty slots, allowing for efficient replacement of idle tones with information-carrying signals or vice versa, thereby reducing power disturbances and increasing the speed of signal addition and removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If channel power optimization is performed to limit power changes during signal addition/deletion, then power stability is improved, but the channel slot add/delete process becomes slow
Solution Approach 1:
The system performs preliminary equalization of all wavelength channels to a common power level before signal addition or deletion operations. This preliminary action ensures that when signals are added or deleted, the power changes are minimized because all channels are already at the same power level, eliminating the need for extensive post-operation power optimization and thereby speeding up the channel slot add/delete process while maintaining power stability
2Stability of the object's composition
If the number of signals on channels to be added or deleted is kept small, then power changes are limited, but the channel slot add/delete process becomes slow
Solution Approach 1:
The system changes the power parameter of all wavelength channels to a common power level through equalization before signal addition or deletion. This parameter change ensures that when multiple signals are added or deleted simultaneously, the power changes are minimized because all channels are already at the same power level, allowing faster channel slot operations without excessive power changes
3Stability of the object's composition
If channel power optimization is performed, then power stability is improved, but operational complexity increases
Solution Approach 1:
The system performs preliminary equalization of all wavelength channels to a common power level before signal addition or deletion operations. This preliminary action simplifies subsequent operations because the equalized state serves as a stable baseline, reducing the need for complex post-operation power optimization and thereby reducing operational complexity while maintaining power stability
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 faster and more stable signal addition and removal processes, minimizing power changes in other channels and potentially making DWDM systems 'digital' in nature, with improved optical signal-to-noise ratio and reduced operational complexity.
Implementation Method 1
generating the plurality of idle tones from amplified spontaneous emission (ASE) of an optical gain medium
Implementation Method 2
Optical networks also include optical amplifiers between the ROADM devices to amplify the signal during transmission. A common example of an optical amplifier is an Erbium Doped Fiber Amplifier (EDFA).
Implementation Method 3
adding and deleting signals on wavelength channel slots causes power changes to other wavelength channels, due to transient and steady state amplification effects of the EDFAs, and fiber Stimulated Raman Scattering (SRS) effect
Data Source
AI summary
The present disclosure includes methods and systems in which idle tones are added at an ingress and terminated at an egress of a given fiberoptic communication link between ROADM nodes. An equalization process can be performed across the spectrum of available wavelength channels and then a determination can be made of a number of channels that can be added or dropped at a given time that meet a maximum threshold for change in power of the channels in the available wavelength. As channels without information-carrying signals are filled with idle tones, the stability of the optical system can be improved as there is less variability in power change when all of the channels have a substantially similar nominal power and a signal on one or more of those channels are added or removed.