Single Channel Four-Port WDM Group Delay Equalizer
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Solution Overview
Problem
Conventional group delay equalizers in WDM systems require multiple three-port devices, leading to increased design and manufacturing costs, as well as complex alignments, due to bidirectional signal flow and longer fiber paths, which complicates the compensation for differential delays between multiple wavelengths.
Innovation Solution
A single channel four-port WDM device is employed, with a filter and specific port connections to compensate for group delay by transmitting wavelengths through different paths, ensuring equal fiber length to match transmission time differences, thereby simplifying the design and reducing costs by eliminating the need for multiple alignments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple three-port WDM devices are used for group delay compensation, then the group delay between wavelengths can be compensated, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines multiple three-port WDM devices into a single four-port WDM device that performs the same group delay compensation function. The four-port device integrates the functionality of separating wavelengths into different paths and compensating for differential delays in a single unit, eliminating the need for multiple separate devices and reducing system complexity.
Solution Approach 2:
The four-port WDM device performs multiple functions simultaneously: it separates wavelengths into different paths, compensates for group delay differences, and manages signal routing all within a single device. This multi-functional approach replaces the need for multiple specialized three-port devices, reducing both complexity and cost.
2Reliability
If multiple three-port WDM devices are used for group delay compensation, then the group delay between wavelengths can be compensated, but the manufacturing cost increases
Solution Approach 1:
The patent combines multiple three-port WDM devices into a single four-port WDM device that performs the same group delay compensation function. The four-port device integrates the functionality of separating wavelengths into different paths and compensating for differential delays in a single unit, eliminating the need for multiple separate devices and reducing system complexity.
3Reliability
If bidirectional signal flow is used in conventional equalizers, then group delay compensation can be achieved, but the alignment complexity increases
Solution Approach 1:
The patent inverts the conventional bidirectional signal flow approach by implementing unidirectional signal flow through the four-port WDM device. Instead of signals traveling in multiple directions through multiple devices, the signal flows in one direction through a single device, simplifying the alignment requirements and reducing complexity.
4Reliability
If longer fiber paths are used in conventional equalizers, then group delay compensation can be achieved, but the device complexity increases
Solution Approach 1:
The patent combines multiple three-port WDM devices into a single four-port WDM device that performs the same group delay compensation function. The four-port device integrates the functionality of separating wavelengths into different paths and compensating for differential delays in a single unit, eliminating the need for multiple separate devices and reducing system complexity.
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
The single channel four-port WDM device effectively compensates for group delay with reduced costs and complexity, providing unidirectional signal flow and minimizing the number of alignments required, thus enhancing the efficiency and cost-effectiveness of group delay equalization.
Implementation Method 1
A first wavelength in the plurality of wavelengths passing through the filter, the remaining wavelengths in the plurality of wavelengths reflecting from the filter
Implementation Method 2
the fiber length L being equal to the transmission difference between a first transmission delay experienced by the first wavelength and a second transmission delay experienced by the remaining wavelengths traveling through the fiber path
Data Source
AI summary
A group delay compensation equalizer is disclosed that employs a single channel four-port WDM device for compensating the group delay experienced by a plurality of wavelengths transmitted over different paths. The transmission differential between two wavelengths is compensated by transmitting the two wavelengths through two different paths where the fiber length in reflecting the second wavelength is equal to the transmission time difference between the two wavelengths. The single channel four-port group delay equalizer effectively provides a unidirectional signal flow, as compared to the conventional equalizer that transmits optical signals bi-directionally. The present invention reduces the cost of a group delay equalizer by simplifying the use of multiple three-port WDM devices into a single channel four-port WDM device. The present invention further reduces the number of alignments required to just one on the transmission side since the group delay equalizer now has one transmission output, rather than two transmission outputs in a prior solution.