Stretched Single Optical Span Using Pilot Signal and EDFA
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical networking systems face challenges with high optical power levels, which can be hazardous and lead to system damage, increased complexity, and cost due to the need for automatic safety systems and additional instrumentation.
Innovation Solution
The solution involves configuring conventional off-the-shelf Erbium Doped Fiber Amplifiers (EDFAs) to create a stretched single optical communication span, using a pilot signal and high noise tolerant optical modems to operate within safe power levels, thereby avoiding the need for high power solutions like distributed Raman amplification or remotely pumped amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If distributed Raman amplification or ROPA is used to extend communication span beyond 50 dB loss, then the communication reach is improved, but the optical power levels become hazardous and require complex safety systems
Solution Approach 1:
The patent changes the operating parameters by using conventional EDFAs configured for low-power operation instead of high-power Raman amplification. The EDFA is operated in gain-controlled mode with automatic shutdown at low input power thresholds, maintaining communication functionality while operating below hazardous power levels throughout the fiber span.
Solution Approach 2:
The patent uses conventional off-the-shelf EDFAs that are already certified for Hazard 1M safety levels, avoiding the need for expensive specialized high-power amplifier designs. These standard components can be deployed without additional safety instrumentation, reducing both cost and complexity.
2Length of stationary object
If high optical power sources (500 mW to multi-W) are used to achieve extended span communication, then the communication reach is improved, but the risk of fiber plant damage and safety hazards increases
Solution Approach 1:
The patent converts the inherent safety limitation of conventional EDFAs (automatic shutdown at low power) from a potential communication limitation into a protective feature. The gain-controlled mode with automatic shutdown at −30 dBm ensures the system never operates at hazardous power levels, protecting the fiber plant while maintaining communication functionality through proper gain management.
Solution Approach 2:
Instead of using excessive high-power amplification, the patent applies partial action by using conventional EDFAs operated precisely at the boundary of safety limits (Hazard 1M). The system provides sufficient amplification for extended span communication while deliberately operating below the threshold that would cause fiber damage, achieving the minimum necessary power for functionality without excess.
3Reliability
If conventional EDFAs are used in gain-controlled mode with automatic shutdown, then safety is improved, but the input power must be maintained above a threshold which limits span extension
Solution Approach 1:
The patent applies preliminary action by adding a pilot signal before the EDFA that ensures the amplifier always has sufficient input power to maintain gain-controlled operation. The pilot signal is combined with the weak communication signal to guarantee the total input power remains above the −30 dBm shutdown threshold, enabling the EDFA to provide consistent amplification for extended span communication without risking hazardous power levels.
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 allows for simple, low-cost, and safe deployment of optical communication systems over high-loss spans, extending the reach of non-Raman systems by >10 dB and maintaining safety within Class 1 Hazard 1M limits.
Implementation Method 1
amplifying the one or more optical signals and the pilot signal with a pre-amplifier that is an Erbium Doped Fiber Amplifier (EDFA)
Data Source
AI summary
A method of implementing a stretched single optical communication span includes receiving one or more optical signals from an optical fiber span having high loss; adding a pilot signal to the one or more optical signals, subsequent to the receiving; and amplifying the one or more optical signals and the pilot signal with a pre-amplifier that is an Erbium Doped Fiber Amplifier (EDFA). Advantageously, the stretched single span operates below a Hazard 1M environment. A node in a stretched single optical communication span includes an optical multiplexer connected to an optical fiber span having high and a pilot signal, and configured to output a combination of one or more optical signals from the optical fiber span and the pilot signal; and a pre-amplifier that is an EDFA configured to receive the output of the optical multiplexer and provide amplification of the one or more optical signals and the pilot signal.