Optical Amplifier Turn-Up Sequence for Raman ASE Recovery
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Solution Overview
Problem
Conventional optical network systems fail to effectively manage turn-up procedures for amplifiers, particularly when high reflections persist due to counter-propagating Raman amplifiers, leading to amplifiers remaining in Automatic Power Reduction (APR) states and preventing successful fiber span recovery after installation or fiber cut restoration.
Innovation Solution
Implementing a method where the local Erbium-Doped Fiber Amplifier (EDFA) is turned on before the remote Raman amplifier, using a Forward Defect Indicator (FDI) flag to control the turn-up sequence, and performing an Automatic Laser Shut-Off (ALSO) process to ensure safe and efficient power management, thereby allowing the local amplifier to reach target power levels while ignoring backward-directed Amplified Spontaneous Emission (ASE) from the Raman amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the remote Raman amplifier is turned on before the local EDFA, then the remote amplifier can start providing amplification, but the backward-directed ASE from the Raman amplifier causes the local EDFA to enter APR condition and prevents successful turn-up
Solution Approach 1:
The system performs preliminary actions by sending the FDI flag from the downstream node to the upstream node before the remote Raman amplifier is activated. This flag预先 indicates that the downstream amplifier is about to turn on, allowing the upstream EDFA to prepare its turn-up sequence first. This preliminary signaling resolves the contradiction by establishing the correct turn-up order without delaying the overall system activation.
Solution Approach 2:
The FDI flag acts as an intermediary mechanism between the downstream Raman amplifier and the upstream EDFA. It carries information about the downstream amplifier's status and triggers the upstream amplifier's turn-up sequence at the appropriate time. This intermediary resolves the timing conflict by mediating the interaction between the two amplifiers, ensuring they turn on in the correct sequence without direct interference.
2Object-affected harmful factors
If the local EDFA waits for high reflection to clear before turning up, then laser safety is maintained, but the amplifier remains in APR condition indefinitely when the reflection is actually caused by Raman ASE
Solution Approach 1:
The FDI flag serves as an intermediary that provides additional information to the upstream EDFA about the source of detected reflections. When the flag is set, it indicates that high reflections are expected due to downstream Raman amplifier activity rather than actual fiber faults. This allows the EDFA to distinguish between safety-critical reflections and benign Raman-induced reflections, maintaining safety while enabling successful turn-up.
Solution Approach 2:
The system changes the operational parameters of the EDFA based on the FDI flag status. When the flag is set, the EDFA modifies its reflection threshold behavior and turn-up sequence, allowing it to proceed with turn-up despite detecting high reflections. This parameter change resolves the contradiction by adapting the safety mechanisms to the specific context indicated by the flag.
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 automatic recovery of fiber spans during installation or fiber-cut restoration by prioritizing the local amplifier's turn-up, maintaining safety features and preventing false reflections, thus ensuring successful traffic carrying capabilities without compromising laser safety or fiber integrity.
Implementation Method 1
a first set of amplifiers deployed at an upstream node... the first turn-up process is configured to move the EDFA from an Automatic Power Reduction (APR) condition to a target output power condition
Implementation Method 2
a second set of amplifiers deployed at a downstream node... the second set of amplifiers may include at least a Raman amplifier
Implementation Method 3
prevent backward-directed Amplified Spontaneous Emission (ASE) from a downstream Raman amplifier
Data Source
AI summary
Systems and methods are provided for creating a sequence of turn-up processes for amplifiers. A method, according to one implementation, includes determining when a fiber span is initially installed in an optical line system or when an Optical Line Failure (OLF) in the fiber span has recovered. The optical line system includes a first set of amplifiers deployed at an upstream node and a second set of amplifiers deployed at a downstream node, the upstream node connected to the downstream node via the fiber span. In response to determining that the fiber span is initially installed in the optical line system or that an ORL in the fiber span has recovered, the method also includes sending a flag from the upstream node to the downstream node to allow the first set of amplifiers to perform a first turn-up process before the second set of amplifiers perform a second turn-up process.