Optical Add/Drop Multiplexer Dual Control Mode ASE Noise Management
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Solution Overview
Problem
In optical telecommunication systems using wavelength division multiplexing (WDM), the accumulation of ASE noise across multiple stages of optical add/drop multiplexers (OADMs) leads to incorrect transitions between control states, causing data errors due to excessive signal levels in unused wavelength bands, which limits the telecommunication range and increases the risk of crosstalk.
Innovation Solution
Implementing an optical add/drop multiplexer with a dual control mode system that differentiates between inserted and pass-through signals, using feedback control to manage optical power levels, preventing unnecessary transitions and maintaining target signal levels, thereby reducing ASE noise accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If optical amplifiers are used to amplify wavelength ranges in WDM systems, then telecommunication capacity and range are improved, but ASE noise accumulates and causes data errors
Solution Approach 1:
The patent extracts and removes ASE noise from the optical signal path by placing optical filters at strategic locations. Specifically, optical filters are positioned between the optical drop filter and optical multiplexer in each OADM stage to selectively remove ASE noise while allowing signal lights to pass through, thereby eliminating the harmful noise accumulation that limits system capacity
Solution Approach 2:
The patent implements feedback control by using optical monitors to detect the optical power of signal lights and feeding this information back to control units. This feedback mechanism allows the system to automatically adjust optical filters and attenuators to maintain optimal signal levels while minimizing ASE noise accumulation across multiple stages
2Object-generated harmful factors
If optical filters are placed synchronously with each signal light to remove ASE noise, then ASE noise is reduced, but the system complexity increases
Solution Approach 1:
The patent makes the optical filter control unit multi-functional by enabling it to perform both manual control mode (receiving control signals from external devices) and automatic control mode (using feedback from optical monitors). This universal control unit handles multiple functions including ASE noise removal, signal level maintenance, and adaptive filtering, thereby reducing overall system complexity despite the added filtering components
Solution Approach 2:
The patent implements dynamic control of optical filters by allowing the filter control unit to adjust filter characteristics in real-time based on feedback signals. The system can dynamically switch between manual and automatic control modes, and continuously adjust optical power levels, making the filtering system adaptable to changing conditions rather than a static complex structure
3Extent of automation
If automatic control state is transitioned based on signal level thresholds, then signal level control is automated, but incorrect transitions occur due to ASE noise
Solution Approach 1:
The patent applies preliminary action by having the optical filter control unit remove ASE noise from the optical path before the signal light reaches subsequent OADMs. By proactively eliminating the noise at the source (first OADM stage), the system prevents incorrect threshold-based transitions from occurring at later stages, ensuring reliable automatic control throughout the network
Solution Approach 2:
The patent introduces optical filters as intermediary components between the signal light source and subsequent processing stages. These filters act as mediators that clean the optical signal by removing ASE noise, thereby protecting the automatic control system downstream from making incorrect decisions based on noisy signal levels
4Length of moving object
If multiple stages of OADMs are connected to extend telecommunication range, then distance is improved, but ASE noise accumulates and exceeds threshold levels
Solution Approach 1:
The patent segments the optical network into discrete stages, with each OADM stage equipped with its own optical filter control unit. By dividing the long transmission path into manageable segments and placing filtering capability at each segment boundary, the system prevents ASE noise from accumulating across multiple stages while maintaining extended telecommunication range
Data Source
AI summary
The present invention provides an optical add/drop multiplexer including an optical power control unit for performing a control of an optical power by the unit of each signal light included in the wavelength multiplexed light, wherein the optical power control unit includes control logic for implementing a first control mode in which a transition to an automatic control of the optical power and release from the aforementioned control are carried out by comparing the optical power with a threshold value, and a second control mode in which a transition to an automatic control of the optical power is carried out based on control information of a notification by another of the optical add/drop multiplexers and release from the automatic control is carried out based on the comparison between the optical power and the threshold value.