Few-Mode Fiber Coupling Efficiency via Brillouin Gain Analysis
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Solution Overview
Problem
Existing methods for measuring loss and inter-modal crosstalk in few-mode optical fibers using Brillouin gain analysis face errors due to non-specific optical frequency differences, leading to inaccurate loss measurements.
Innovation Solution
The proposed method involves pulsating pump light to propagate as both fundamental and higher-order mode light, inputting probe light with a frequency shift within the Brillouin frequency range, measuring Brillouin gain distribution, and using mathematical expressions to calculate coupling efficiency and crosstalk at the connection point, incorporating Brillouin gain coefficients and transmittance data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Brillouin gain analysis is used to measure loss for each mode in few-mode optical fiber, then transmission capacity assessment is enabled, but measurement accuracy deteriorates due to non-specific optical frequency differences causing errors in loss measurement
Solution Approach 1:
The patent segments the Brillouin gain spectrum into multiple frequency components and performs separate analysis for each frequency difference between pump light and probe light. By dividing the measurement into multiple discrete frequency points, the method identifies specific frequency differences where mode-specific Brillouin gain occurs, thereby improving measurement accuracy and reliability of loss characterization in few-mode optical fibers.
2Productivity
If mode multiplex transmission using few-mode fibers is implemented to accommodate future traffic increases, then transmission capacity is improved, but mode-dependent loss and inter-modal crosstalk at connection points limit the transmission capacity
Solution Approach 1:
The patent replaces physical measurement methods with optical field analysis. By using Brillouin gain analysis to extract mode-dependent loss and inter-modal crosstalk characteristics from the optical field interactions, the method enables accurate assessment of transmission quality without requiring physical intervention at connection points, thus maintaining high transmission capacity while ensuring transmission quality.
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 enables accurate acquisition of inter-modal coupling efficiency at the connection point between few-mode fibers, reducing measurement errors and improving transmission capacity assessment.
Implementation Method 1
by setting optical frequencies (wavelengths) of the pump light and the probe light to values within a Brillouin frequency shift range, the probe light is amplified or attenuated via stimulated Brillouin scattering when the pump light and the probe light collide with each other
Data Source
AI summary
This disclosure describes inputting pulsated pump light in a fundamental mode or a first higher-order mode into one end of an optical fiber under test constructed by connecting two optical fibers in series; inputting probe light having an optical frequency difference within a Brillouin frequency shift range with respect to the pump light into the other end of the optical fiber under test in the fundamental mode or the first higher-order mode; measuring a Brillouin gain distribution related to a distance of transmitted light intensity of probe light output from the one end into which the pump light was input; and calculating each inter-modal coupling efficiency at the connection point of the optical fiber under test.