Dummy Light Generation Device for WDM Transmission Quality
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Solution Overview
Problem
In optical communication systems using WDM, the use of CW light as dummy light leads to polarization dependency loss and gain, causing deterioration in transmission quality due to nonlinear effects like cross-phase modulation, while ASE light, although non-polarized, affects adjacent signal lights with random amplitude fluctuations, also degrading transmission quality.
Innovation Solution
A dummy-light generating device that outputs continuous light, modulates it into intensity-modulated lights with different polarization planes and delays one by half the modulation cycle, combining them to produce dummy light with fixed intensity and multiple polarization planes, reducing polarization dependency loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CW light is used as dummy light, then the amplification band can be fully utilized from initial introduction time, but polarization dependency loss and gain occur causing deterioration in transmission quality
Solution Approach 1:
The invention segments the dummy light into multiple polarization components (first polarization component and second polarization component) with different polarization states. This segmentation allows the dummy light to interact differently with signal lights having various polarization states, thereby reducing polarization dependency loss and gain effects while maintaining full utilization of the amplification band from initial introduction time.
2Reliability
If ASE light is used as dummy light, then polarization dependency is reduced, but random amplitude fluctuations affect adjacent signal lights deteriorating transmission quality
Solution Approach 1:
The invention changes the parameters of the dummy light by controlling the intensity relationship between different polarization components. Specifically, the intensity of the first polarization component and the second polarization component are set to satisfy specific intensity relationships that compensate for polarization dependency effects. This parameter control stabilizes the overall intensity of the dummy light and reduces harmful fluctuations affecting adjacent signal lights, while maintaining reduced polarization dependency.
3Device complexity
If dummy light with single polarization plane is used, then device complexity is reduced, but polarization dependency loss occurs leading to transmission quality deterioration
Solution Approach 1:
The invention introduces dynamic control of polarization components by adjusting the intensity of the first polarization component and the second polarization component based on the polarization states of signal lights. This dynamic adjustment mechanism allows the dummy light to adapt to different polarization conditions in the transmission line, reducing polarization dependency loss and gain effects while maintaining practical device complexity through controlled intensity relationships.
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 generates dummy light that minimizes signal light transmission quality deterioration by reducing polarization dependency loss and maintaining stable light intensity, similar to non-polarized light, thereby enhancing overall transmission quality.
Implementation Method 1
a modulated-light generating unit to generate, using the continuous light, first intensity-modulated light subjected to intensity modulation
Implementation Method 2
a polarization combiner to perform polarization combination of the first intensity-modulated light and second intensity-modulated light
Data Source
Figure 1
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AI summary
A dummy-light generating device 1 according to the present invention includes a CW light source 11 that outputs CW light, a modulated-light generating unit 50 that generates, using the continuous light, first intensity-modulated light subjected to intensity modulation and second intensity-modulated light delayed by a half time of a modulation cycle of the first intensity-modulated light with respect to the first intensity-modulated light and having a polarization plane different from a polarization plane of the first intensity-modulated light, and a polarization combiner 17 that performs polarization combination of the first intensity-modulated light and second intensity-modulated light and outputs light after the polarization combination as dummy light.