Optical Multiplexer Dummy Light Control for Submarine Cable Gain Stability
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Solution Overview
Problem
In optical submarine cable systems, the dry-ROADM function's noise level issues lead to deterioration of optical signal characteristics when the noise level exceeds a threshold, causing dummy light to be extinguished incorrectly, which increases power and degrades other optical signals.
Innovation Solution
An optical multiplexer/demultiplexer system that includes an optical strength monitor to determine signal and noise wavelength bands, a wavelength selective switch to pass the signal wavelength band as a primary signal, and dummy light generation to extinguish the dummy light in the signal wavelength band, allowing for accurate multiplexing and suppression of signal characteristic deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dummy light is inserted into wavelength bands to stabilize gain characteristics of optical amplification repeaters, then gain stability is improved, but when noise level exceeds threshold, dummy light is extinguished incorrectly causing power increase and signal characteristic deterioration
Solution Approach 1:
The system uses an optical strength monitor to continuously measure the strength of optical signals in each wavelength band and feeds this information back to the control unit. The control unit compares the measured strength with a threshold value to dynamically control the dummy light generation unit, turning it on or off based on actual signal conditions. This feedback mechanism prevents incorrect extinction of dummy light due to noise while maintaining gain stability.
Solution Approach 2:
The patent replaces mechanical or simple threshold-based switching mechanisms with an optical measurement and control system. Instead of using fixed thresholds that are susceptible to noise interference, the system uses an optical strength monitor to accurately detect signal presence and control dummy light generation accordingly, substituting a more sophisticated optical-electrical-optical control loop for simpler but less accurate mechanisms.
2Measurement precision
If the threshold value for dummy light extinction is set low to allow signal detection, then signal presence is detected more sensitively, but noise is also detected causing incorrect dummy light extinction and power increase
Solution Approach 1:
The control unit continuously receives feedback from the optical strength monitor and dynamically adjusts dummy light generation based on real-time measurements. This continuous feedback loop allows the system to distinguish between actual signals and noise by observing signal characteristics over time, maintaining high detection sensitivity while rejecting noise interference.
Solution Approach 2:
The system performs preliminary measurement and evaluation of optical signal strength before making the decision to extinguish dummy light. By measuring the optical strength first and comparing it with the threshold value in advance, the system ensures that dummy light is only extinguished when a genuine signal is detected, preventing premature extinction due to noise while maintaining sensitivity.
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 solution effectively suppresses the deterioration of optical signal characteristics even when the noise level is high, by accurately controlling the dummy light based on measured signal strengths, ensuring stable power distribution and improved transmission quality.
Implementation Method 1
an optical strength monitor to determine signal and noise wavelength bands by measuring strengths of optical signals in a plurality of wavelength bands
Implementation Method 2
a wavelength selective switch to pass the signal wavelength band as a primary signal
Implementation Method 3
dummy light generation to extinguish the dummy light in the signal wavelength band
Implementation Method 4
allowing for accurate multiplexing and suppression of signal characteristic deterioration
Data Source
AI summary
An optical multiplexer/demultiplexer according to an example embodiment includes: an OCM configured to measure a strength of each of optical signals in a plurality of wavelength bands input to a WSS and to determine an optical signal wavelength band and a noise wavelength band based on the measured strengths; the OCM configured to pass the optical signal in the optical signal wavelength band determined by the OCM as a primary signal; a dummy light generation unit configured to generate dummy light in which the optical signal wavelength band has been extinguished; and an optical coupler configured to multiplex the primary signal output from the WSS with the dummy signal into a wavelength division multiplexing optical signal and to output the wavelength division multiplexing optical signal to an optical transmission path.