Mode MUX Feedback Control via Pilot Tone Tuning
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Solution Overview
Problem
Current optical transmission systems face limitations in increasing system capacity due to fiber loss, limited wavelength resources, and impairments caused by fabrication errors and temperature fluctuations, which restrict the use of additional multiplexing dimensions beyond wavelength and polarization.
Innovation Solution
The method involves modulating WDM signals with pilot tones of different frequencies, spatially multiplexing these signals using a mode multiplexer, detecting the pilot tones, and tuning the multiplexer to reduce crosstalk caused by fabrication errors, thereby improving system performance and increasing tolerance to such errors without the need for massive MIMO at the receiver side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spatial division multiplexing with mode MUX/DEMUX is used to increase system capacity, then system capacity increases, but fabrication errors cause increased impairments and limitations
Solution Approach 1:
The patent applies preliminary action by modulating each WDM signal with a pilot tone of different frequency before spatial multiplexing. This pilot tone is injected in advance to enable subsequent detection and feedback control, allowing the system to pre-establish the means for identifying and correcting fabrication errors in the mode MUX/DEMUX components
Solution Approach 2:
The patent implements feedback control by detecting the pilot tones from the multi-mode signal and using this information to tune the mode MUX. The detected pilot tone characteristics provide feedback about the actual performance of the mode multiplexer, enabling real-time adjustment to compensate for fabrication errors and maintain optimal system performance
2Reliability
If massive MIMO is used at receiver side to compensate for MUX imperfections, then crosstalk is reduced, but power consumption increases
Solution Approach 1:
The patent performs preliminary action by tuning the mode MUX at the transmitter side using pilot tone detection and feedback control. This pre-compensation approach corrects MUX imperfections before the signal reaches the receiver, eliminating the need for complex massive MIMO processing at the receiver and thereby reducing power consumption
Solution Approach 2:
The patent introduces an intermediary feedback control mechanism using pilot tones. Instead of directly implementing complex receiver-side processing like massive MIMO, the system uses the pilot tone as an intermediary to carry information about MUX performance, enabling simple receiver operation while achieving crosstalk reduction through transmitter-side adjustment
3Productivity
If mode MUX/DEMUX components are used for spatial multiplexing, then system capacity increases, but fabrication errors lead to increased impairments
Solution Approach 1:
The patent applies feedback control by detecting the pilot tones that have passed through the mode MUX and using this information to tune the MUX parameters. This closed-loop feedback mechanism enables the system to automatically compensate for fabrication errors, increasing tolerance to manufacturing imperfections while maintaining high system capacity
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the mode MUX parameters based on pilot tone detection results. The system changes operational parameters such as coupling ratios or phase shifts in response to detected fabrication errors, thereby compensating for manufacturing variations and maintaining optimal performance
Data Source
AI summary
Aspects of the disclosure provide for methods and systems for feedback control of mode MUX and DEMUX. An aspect of the disclosure provides for a method associated with a mode MUX. The method includes modulating each WDM signal of a first set of WDM signals with a pilot tone of different frequency. The method further includes spatially multiplexing the first set of WDM signals to generate a multi-mode signal. The method further includes detecting the pilot tones from the multi-mode signal. The method further includes tuning the mode MUX based on the detecting. Another aspect of the disclosure provides for a method associated with a mode DEMUX. The method includes spatially demultiplexing a multi-mode signal into a set of WDM signals. The method further incudes detecting pilot tones from the set of WDM signals and tuning the mode DEMUX based on the detecting.