Optical Fiber Amplifier Gain and Slope Control for C+L-Band Precision
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Solution Overview
Problem
The existing Raman fiber amplifiers face challenges in achieving high-precision control over gain and slope in ultra-wideband C+L-band systems due to non-linear pump laser relationships and energy transfer between wavelengths, making proportional power control ineffective.
Innovation Solution
A control method and optical fiber amplifier that adjusts target gain and slope using offset gains and slopes calculated based on signal optical powers, with feedback mechanisms to achieve precise control, including calculations involving preset gains and slopes, and photodiode detection to account for environmental deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If proportional power control is used for pump lasers in C+L-band systems, then the control method remains simple, but the gain and slope control precision deteriorates due to non-linear pump laser relationships and energy transfer between wavelengths
Solution Approach 1:
The patent transforms the control parameters from direct proportional power relationships to a two-stage adjustment process: first adjusting target gain with a first offset gain, then adjusting the post-initial-adjustment target gain with a second offset gain. This parameter transformation resolves the non-linear relationship issue while maintaining controllable complexity.
Solution Approach 2:
The patent implements feedback mechanisms by calculating offset gains based on actual signal optical powers measured at different pump laser power levels. The first offset gain is calculated from signal optical powers at initial target power, and the second offset gain is calculated from signal optical powers at adjusted target power, creating a closed-loop control system that improves precision.
2Measurement precision
If offset gain adjustment is implemented to improve control precision, then the gain and slope control precision improves, but the device complexity increases due to additional calculation and adjustment stages
Solution Approach 1:
The patent segments the gain control process into distinct stages: initial target gain adjustment using the first offset gain, followed by post-initial-adjustment target gain adjustment using the second offset gain. This segmentation allows each stage to be optimized independently while maintaining overall system manageability.
Solution Approach 2:
The patent performs preliminary calculations of offset gains before the actual pump laser power adjustment. The first offset gain is calculated based on signal optical powers at the initial target power, and the second offset gain is calculated based on signal optical powers at the adjusted target power, preparing control parameters in advance to streamline the adjustment process.
3Manufacturing precision
If multiple offset gains are calculated based on signal optical powers, then the control accuracy improves, but the calculation time and processing complexity increase
Solution Approach 1:
The patent calculates offset gains in advance at predetermined pump laser power levels (initial target power and adjusted target power) rather than continuously during operation. This preliminary calculation approach prepares control parameters beforehand, reducing real-time processing requirements while maintaining high control accuracy.
Solution Approach 2:
The patent implements periodic recalculation of offset gains at specific operational stages (when target power changes) rather than continuous recalculation. This periodic approach balances the need for accurate control parameters with the constraint of calculation time, updating gains only when necessary to maintain precision.
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
Enables high-precision control of gain and slope in optical fiber amplifiers, ensuring accurate reporting of unamplified source signal power and maintaining stability despite environmental variations.
Implementation Method 1
For the existing Raman fiber amplifier, each pump laser is controlled by a proportional relationship in the current C-band or L-band Raman control system. However, in the ultra-wideband C+L-band system, the pump wavelength distribution is much wider than that of the only C-band or L-band, and the Raman effects between the pump lasers are obvious.
Data Source
AI summary
Disclosed are a control method and an optical fiber amplifier. The optical fiber amplifier is configured to execute the control method. The method comprises: initially adjusting a target gain on the basis of a first offset gain to obtain the post-initial-adjustment target gain; when the actual power of the pump laser reaches target power determined on the basis of the post-initial-adjustment target gain, obtaining, on the basis of a first signal optical power and a second signal optical power, a second offset gain and a first offset slope through calculation; adjusting again the post-initial-adjustment target gain according to the second offset gain to obtain a adjusted target gain; and adjusting a target slope according to the first offset slope to obtain a adjusted target slope. This solution can provide high precision control for the gain and the slope of the optical fiber amplifier.