Inline Pump Sharing for Remote Optical Amplifiers
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Solution Overview
Problem
Current optical fiber transmission links with remotely-pumped Er post-amplifiers (ROPA) require dedicated pump-delivery fibers for Tx ROPAs, increasing system cost and complexity, while using the transmission fiber for pump delivery leads to excess noise generation.
Innovation Solution
Sharing pump power between fibers carrying traffic in opposite directions eliminates co-propagating Raman interactions, allowing for remote pumping of both Tx and Rx ROPAs without dedicated fibers, thereby reducing system complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dedicated pump-delivery fibers are used for Tx ROPA, then optical budget is improved, but system cost and complexity increase
Solution Approach 1:
The patent combines the pump delivery function with the existing bidirectional traffic fibers. The same fiber that carries traffic in one direction is used to deliver pump power to the Tx ROPA, while the opposite-direction fiber carries both traffic and returns pump power. This merging eliminates dedicated pump-delivery fibers and reduces system complexity while maintaining optical budget improvements.
Solution Approach 2:
The traffic fibers are given multiple functions: they simultaneously carry bidirectional traffic signals and deliver pump power for both Tx and Rx ROPAs. This multi-functionality approach allows the existing fiber infrastructure to serve dual purposes, avoiding the need for additional dedicated pump-delivery fibers and reducing overall system complexity.
2Device complexity
If transmission fiber is used for pump delivery, then system complexity is reduced, but excess noise is generated
Solution Approach 1:
Instead of using the transmission fiber for co-propagating pump delivery (which causes noise), the patent uses counter-propagating pump delivery. The pump power is launched from the Rx ROPA end and travels in the opposite direction to the traffic signals, eliminating Raman interaction-induced noise while still using the transmission fiber for pump delivery.
Solution Approach 2:
The patent introduces an optical circulator as an intermediary device at each end to separate the pump power and traffic signals. The circulator directs pump power into the transmission fiber while allowing traffic signals to pass through, and at the far end, it separates the returning pump power from the outgoing traffic, preventing direct interaction between pump and signal that would generate noise.
3Reliability
If dedicated Tx ROPA pump sources are used, then optical budget is improved, but system cost increases
Solution Approach 1:
The patent merges the pump sources for Tx and Rx ROPAs into a single shared pump source. The pump power is launched into the fiber, travels to the Rx ROPA, and the remaining power is used to pump the Tx ROPA on the return journey. This shared pumping approach eliminates the need for separate dedicated Tx ROPA pump sources while maintaining sufficient optical budget through the counter-propagating architecture.
Data Source
AI summary
A new transmission link configuration with remote Er post- and pre-amplifiers where pump power is shared between a pair of fibers carrying traffic in opposite directions is proposed. A budget increase of >4 dB is demonstrated.