Optical Amplifier Output Power Control for Heterogeneous Fibre Spans
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Solution Overview
Problem
Existing optical transmission systems face challenges in achieving optimum performance due to heterogeneity in fibre types and span losses, as prior art methods are based on homogeneous assumptions and require additional costly components for non-linear effect compensation.
Innovation Solution
The method involves setting output power relative to a reference output power by compensating deviations in span loss and non-linear tolerance using proportional contributions, allowing for flexible operation in heterogeneous systems without the need for additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical phase conjugation is used to compensate non-linear effects, then non-linear effects are compensated, but device complexity and cost increase due to additional components
Solution Approach 1:
The patent extracts the non-linear effect compensation function from the optical signal path by using digital signal processing in the electrical domain. Instead of adding optical components to compensate non-linearities, the system transmits the optical signal through the fibre and then compensates for non-linear effects electronically at the receiver, thereby achieving compensation without increasing optical device complexity
Solution Approach 2:
The patent replaces the optical mechanical system (optical phase conjugation devices) with an electrical/digital processing system. Non-linear effect compensation is achieved through digital signal processing algorithms rather than optical hardware, substituting complex optical components with electronic processing that achieves the same functional result
2Reliability
If optical phase conjugation with scaling is used, then non-linear effects are compensated, but adaptability is reduced due to requirement for specially designed systems
Solution Approach 1:
The patent creates a universal solution that can be applied to existing optical transmission systems regardless of fibre type or span configuration. The digital signal processing approach works with standard optical components and existing fibre infrastructure, making the non-linear compensation technique universally applicable rather than requiring specially designed systems
Solution Approach 2:
The patent uses digital signal processing to create a mathematical model of the non-linear effects that occurred during transmission, then applies the inverse operation to compensate. This digital copying and processing approach allows the same compensation technique to be applied to any transmission scenario without requiring physical system modifications
3Ease of manufacture
If homogeneous system assumptions are used, then design is simplified, but performance is suboptimal in heterogeneous systems
Solution Approach 1:
The patent changes the approach from assuming uniform system parameters to measuring and adapting to actual system parameters. The system measures span loss and non-linear tolerance for each specific span, then adjusts the pre-amp gain accordingly. This parameter adaptation allows optimal performance in heterogeneous systems while maintaining relatively simple design through automated measurement and adjustment
Data Source
Figure 1~2
AI summary
A method of operating an optical amplifier (4.xb) in an optical transmission system (1) comprising a number of spans (4.x) each having a respective line fibre (4.xa), in particular in an optical transmission system comprising at least two different line fibre types with different tolerances to non-linearities, said amplifier being connected with a given line fibre span with respective characteristic span loss, L, and respective characteristic span non-linear tolerance, C, which may be proportional to one of a maximum authorised power, a number of spans times power, and a non-linear cumulated phase, expressed on a dB scale, for operating said given span at an input power, P, corresponding to an output power of said amplifier. The proposed method comprises the step of setting said output power relative to a reference output power, Pref, defined for a reference span with reference span loss, Lref, and reference span non-linear tolerance, Cref, said step of setting said output power comprising: - compensating a first deviation in span loss between said reference span and said given span by means of a first contribution to said output power relative to said reference output power; and - compensating a second deviation in span non-linear tolerance between said reference span and said given span by means of a second contribution to said output power relative to said reference output power, in particular by means of a second contribution proportional to said second deviation.