Multi-Core Fiber Crosstalk Characterization From One-End Backscatter
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods struggle to accurately evaluate bidirectional crosstalk in uncoupled multi-core fibers, especially with small inter-core crosstalk, making it difficult to assess the impact of bends and connections on transmission performance.
Innovation Solution
A device and method that calculates bidirectional crosstalk using backscattered light measurements from both ends of the fiber, employing a test light generation unit, reception unit, and arithmetic processing unit to determine mode coupling matrices and fiber lengths, enabling evaluation of crosstalk influence from one end of the transmission line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the intensity of backscattered light from the adjacent core is extremely smaller than that from the input core, then the dynamic range of the OTDR is insufficient, but measurement of bidirectional crosstalk is still required
Solution Approach 1:
The patent performs preliminary measurements of loss characteristics (attenuation, backscattering coefficient) before conducting the actual bidirectional crosstalk measurement. These preliminary data are used to calculate expected backscattered light intensities, which are then used to set appropriate OTDR measurement ranges and parameters, ensuring that even extremely small crosstalk signals can be detected with sufficient precision.
Solution Approach 2:
The patent introduces an intermediary calculation process that uses measured loss characteristics as intermediate parameters. By calculating the backscattering coefficient and attenuation from preliminary measurements, the system can predict and compensate for signal levels, enabling accurate measurement of extremely small crosstalk signals that would otherwise be undetectable due to OTDR dynamic range limitations.
2Measurement precision
If a test from both ends of the optical fiber is performed, then comprehensive crosstalk evaluation is achieved, but operational difficulties arise in constructing the transmission line
Solution Approach 1:
Instead of performing tests from both ends of the optical fiber (the conventional approach), the patent inverts the approach by performing comprehensive bidirectional crosstalk evaluation from only one end. This is achieved by injecting test light into different cores from the same end and using calculated loss characteristics to evaluate crosstalk in both propagation directions, thereby eliminating the operational difficulties of accessing both ends during transmission line construction.
Solution Approach 2:
The patent creates a universal testing method that can evaluate bidirectional crosstalk characteristics from a single access point. The measurement system performs multiple functions (measuring attenuation, backscattering coefficient, and bidirectional crosstalk) all from one end of the fiber, making the testing process universally applicable during transmission line construction without requiring access to both ends.
3Measurement precision
If small inter-core crosstalk is present in the multi-core fiber, then bidirectional crosstalk evaluation becomes impossible, but transmission line construction still requires such evaluation
Solution Approach 1:
The patent performs preliminary measurements to obtain loss characteristics (attenuation and backscattering coefficient) before conducting bidirectional crosstalk evaluation. These preliminary data allow the system to calculate expected signal levels and set appropriate measurement parameters, enabling reliable evaluation of even extremely small inter-core crosstalk that would otherwise be impossible to detect.
Solution Approach 2:
The patent uses a feedback mechanism where measured loss characteristics are fed back into the calculation process to determine bidirectional crosstalk. The system continuously refines its measurements by using previously obtained data (attenuation, backscattering coefficient) to inform subsequent crosstalk calculations, thereby achieving reliable evaluation of small inter-core crosstalk through iterative refinement.
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 precise evaluation of bidirectional crosstalk even with small inter-core crosstalk, allowing for assessment of the impact of bends and connections on transmission performance in multi-core fiber lines.
Implementation Method 1
measuring intensities of backscattered light output from the core (input core) and its adjacent core
Data Source
AI summary
The present disclosure is a device that detects each loss occurrence point of an optical fiber under test by using at least one of a loss distribution of first backscattered light from a first core or a loss distribution of second backscattered light from a second core, calculates a mode coupling matrix Ti at an i-th loss occurrence point of the optical fiber under test, calculates a fiber length Li of an i-th fiber section having a separation at the i-th loss occurrence point of the optical fiber under test, and calculates bidirectional crosstalk in the first core or the second core by using the calculated mode coupling matrix Ti and fiber length Li and using a fiber loss factor α and power coupling coefficient h of the optical fiber under test measured in advance.