Mode-Dependent Loss Measurement Using Transfer Matrix Extraction
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Solution Overview
Problem
Conventional MDL measurement methods for optical fibers in mode division multiplex transmission systems require complex MIMO processing, including coherent detection and singular value decomposition, leading to increased processing loads and calculation complexity.
Innovation Solution
A method and device for measuring MDL by generating a transfer matrix through light-input and intensity measurement operations across multiple spatial modes, determining MDL per unit fiber length without coherent detection, using a ratio of maximum to minimum matrix or eigen/singular values, and converting this to decibel values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If MIMO processing is performed for MDL measurement, then measurement accuracy is improved, but device complexity and processing load increase
Solution Approach 1:
The patent extracts only the necessary transfer matrix information required for MDL calculation, eliminating the need for full MIMO processing. By taking out only the essential components (transfer matrix elements) rather than performing complete coherent detection and singular value decomposition, the method achieves MDL measurement without the full complexity of MIMO systems.
Solution Approach 2:
Instead of performing coherent detection to obtain complex amplitude information and then calculating MDL through singular value decomposition, the patent inverts the approach by directly measuring intensity information and using it to determine transfer matrix elements. This inversion eliminates the need for coherent detection hardware and complex calculations while maintaining measurement capability.
2Measurement precision
If coherent detection is performed for transfer matrix prediction, then measurement accuracy is improved, but processing load and calculation complexity increase
Solution Approach 1:
The patent uses simple intensity measurements instead of expensive coherent detection systems. By replacing complex coherent detection hardware with simpler intensity measurement devices, the system achieves transfer matrix prediction without the high processing load and equipment cost associated with coherent detection.
Solution Approach 2:
The patent substitutes the optical coherent detection mechanism with a simpler intensity measurement approach. By replacing the complex coherent detection system with direct intensity measurement and mathematical processing of transfer matrix elements, the method reduces processing load while maintaining the ability to predict transfer matrix characteristics.
3Measurement precision
If singular value decomposition is performed on transfer matrix, then MDL calculation accuracy is improved, but calculation complexity and processing load increase
Solution Approach 1:
The patent extracts only the necessary information from the transfer matrix (maximum and minimum eigenvalues or singular values) required for MDL calculation. By taking out only these critical elements rather than performing complete singular value decomposition on the entire matrix, the method achieves MDL measurement with reduced calculation complexity.
Solution Approach 2:
Instead of performing complete singular value decomposition, the patent applies partial action by calculating only the specific eigenvalues or singular values needed for MDL determination. This partial calculation approach provides sufficient accuracy for MDL measurement without the excessive computational burden of full decomposition.
Data Source
AI summary
A present embodiment relates to a MDL measurement method and the like including a structure for enabling MDL measurement without increasing a processing load. The present embodiment sequentially executes, for N (≥2) spatial modes, light-input operation of inputting light of a predetermined intensity to an arbitrary spatial mode, and intensity measurement operation of measuring an output light intensity of each of the N spatial modes including the arbitrary spatial mode, to generate a transfer matrix relating to transmission loss in an optical fiber as a measurement target, and determine at least a linear value of MDL per unit fiber length by using each component value of the generated transfer matrix.