WDM Optical Amplifier Gain Control for Power Stability
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Solution Overview
Problem
In WDM transmission systems, improper control of optical power across multiple reconfigurable optical add/drop multiplexers (ROADMs) leads to unstable communication states due to overshooting or undershooting, especially when each node operates independently, causing instability in the transmission of wavelength division multiplexed optical signals.
Innovation Solution
An optical transmission device with a first amplifier, a wavelength selective switch, and a processor that controls the gain of the first amplifier based on initial settings and corrects it to achieve an average optical power target level, ensuring stable power distribution across multiple nodes by coordinating gain adjustments through a network management system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If each reconfigurable optical add/drop multiplexer controls the gain of the pre-amplifier individually, then the optical power control function is implemented at each node, but the optical power of the WDM optical signal may be controlled improperly causing overshooting or undershooting
Solution Approach 1:
The patent implements a feedback control mechanism where the optical power monitor detects the output optical power and feeds this information back to the amplifier controller, which then adjusts the pre-amplifier gain accordingly. This closed-loop feedback system prevents improper control and stabilizes the optical power across multiple ROADMs by continuously monitoring and adjusting based on actual power levels.
Solution Approach 2:
The patent combines the optical power monitoring and amplifier control functions into an integrated control system. The optical power monitor and amplifier controller work together as a unified mechanism to manage optical power levels, ensuring coordinated adjustment across multiple nodes and preventing the instability that arises from independent control operations.
2Reliability
If the gain control is performed more slowly to prevent overshooting, then the communication state stability is improved, but the time needed for optical power to approach target level becomes longer
Solution Approach 1:
The patent employs periodic adjustment of the pre-amplifier gain in controlled steps rather than continuous or rapid adjustment. The amplifier controller makes incremental gain changes at periodic intervals, allowing the optical power to steadily approach the target level without overshooting, thus balancing stability with reasonable convergence time.
Solution Approach 2:
The system prepares for potential overshooting by implementing damping control mechanisms in advance. The amplifier controller anticipates the system's response to gain changes and adjusts the control parameters beforehand to cushion against excessive oscillations or overshooting, ensuring smooth convergence to the target power level.
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 stabilizes the optical power of wavelength division multiplexed signals by accurately adjusting the gain of amplifiers in WDM transmission devices, preventing overshooting and undershooting, thus maintaining a stable communication state across multiple nodes.
Implementation Method 1
a first optical amplifier configured to amplify a wavelength division multiplexed optical signal received via an optical fiber
Data Source
AI summary
An optical transmission device includes: a first optical amplifier, a WSS (wavelength selective switch), a second optical amplifier and a controller. The first optical amplifier amplifies a received WDM (wavelength division multiplexed) optical signal. The WSS controls optical powers of respective channels multiplexed in the WDM optical signal that is amplified by the first optical amplifier. The second optical amplifier amplifies the WDM optical signal output from the WSS. The controller controls a gain of the first optical amplifier based on initial setting information. The controller corrects the gain of the first optical amplifier such that an average optical power of a plurality of channels multiplexed in the WDM optical signal that is amplified by the first optical amplifier approaches a target level after a specified period of time has elapsed from when the gain of the first optical amplifier is controlled based on the initial setting information.