Multistage Optical Amplifier Gain Control via Pump Ratio
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Solution Overview
Problem
Conventional optical amplifiers in WDM systems face challenges in maintaining proper gain levels across stages, leading to adverse effects on transmission characteristics due to noise figure and multi-pass interference, especially when the gain set value changes, as they lack direct monitoring and control of generated gains in each stage.
Innovation Solution
An optical amplifier configuration with a gain control section that adjusts the ratio of pump light strengths between stages and an optical attenuator to maintain constant gains, using a variable optical attenuator to compensate for changes in gain set values, ensuring the generated gains remain within permissible ranges and optimizing the ratio of pump light strengths to prevent noise figure and multi-pass interference deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the gain set value of the entire optical amplifier is increased, then the overall amplification capability is improved, but the generated gain in the first stage EDF increases excessively causing multi-pass interference and crosstalk
Solution Approach 1:
The patent divides the optical amplifier into multiple stages (first stage EDF and second stage EDF) with independent gain control. By segmenting the amplification process, the system can control the gain distribution across stages to prevent excessive gain in any single stage, thereby reducing multi-pass interference and crosstalk while maintaining overall amplification capability.
Solution Approach 2:
The patent dynamically adjusts the ratio of pump light strengths (Pp1/Pp2) between stages based on the gain set value. When the gain set value increases, the system changes the parameter distribution by increasing the proportion of pump power to the second stage EDF, thereby controlling the generated gain in each stage to remain within proper ranges and preventing harmful interference effects.
2Object-generated harmful factors
If the gain set value of the entire optical amplifier is decreased, then the multi-pass interference is reduced, but the noise figure of the entire optical amplifier increases
Solution Approach 1:
The patent dynamically adjusts the pump light strength ratio (Pp1/Pp2) based on the gain set value. When the gain set value is low, the system increases the proportion of pump power to the first stage EDF to ensure sufficient generated gain, thereby maintaining acceptable noise figure while keeping multi-pass interference within acceptable limits through controlled gain distribution.
Solution Approach 2:
The patent implements a control mechanism that monitors the gain set value and automatically adjusts the pump light distribution ratio between stages. This feedback control ensures that the generated gain in each stage remains within proper ranges, balancing the trade-off between noise figure and multi-pass interference across different operating conditions.
3Speed
If a common gain control section is used for multiple EDFs, then the automatic gain control speed is improved, but the generated gains in individual EDFs cannot be directly monitored and controlled
Solution Approach 1:
The patent segments the gain control function by providing separate gain control sections for each EDF stage. This allows direct monitoring and independent control of the generated gain in each stage, ensuring that gains remain within proper ranges while maintaining coordinated operation across stages.
Solution Approach 2:
The patent controls the ratio of pump light strengths (Pp1/Pp2) as a key parameter to indirectly regulate the generated gain distribution across stages. By adjusting this parameter based on the gain set value, the system achieves precise control over individual stage gains while maintaining overall system performance.
4Device complexity
If the ratio of pump light strengths between stages is kept constant, then the control system is simplified, but the generated gains in individual EDFs change when the gain set value changes
Solution Approach 1:
The patent implements a dynamic control mechanism where the ratio of pump light strengths (Pp1/Pp2) is adjusted according to the gain set value. This dynamic adjustment ensures that the generated gain in each EDF stage remains stable and within proper ranges across different operating conditions, while the control system adapts its complexity only when needed.
Solution Approach 2:
The patent changes the pump light strength ratio (Pp1/Pp2) parameter based on the gain set value to maintain stable generated gains in individual EDFs. This parameter adjustment strategy allows the system to maintain gain stability without requiring complex monitoring and control infrastructure for each stage.
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 configuration allows for quick and effective automatic gain control across the entire optical amplifier, keeping generated gains within proper ranges and mitigating adverse effects on transmission characteristics, even when the gain set value changes, thereby improving the overall performance of the optical amplifier.
Implementation Method 1
optical amplifying sections (1 and 2) in a two-stage configuration, each having an Erbium Doped Fiber (EDF) 11 and 21 and a pump light source (12 and 22)
Data Source
AI summary
According to an aspect of the embodiment of the invention, an optical amplifier including an input port, an output port, a plurality of amplifying parts, an optical attenuator, a gain controller and an optical attenuator controller. The plurality of amplifying parts includes an optical amplification medium and a pumping light source for generating pump light. The optical attenuator is optically connected between the amplifying parts. The gain controller controls the pump light power of the pump sources, respectively, in such a way that the ratio decreases in accordance with the gain set value increasing and the ratio interpose between a first threshold level and a second threshold level. The optical attenuator controller controls attenuation of the optical attenuator in order to maintain the sum of generating gains of the amplifying parts in the gain set value in accordance with a state of the signal light inputted into the input port.