Multimode Fiber EMB Qualification via Wavelength Extrapolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for assessing the Effective Modal Bandwidth (EMB) of multimode optical fibers are limited to a narrow wavelength range, making it costly and time-consuming to measure EMB over a wide wavelength range, such as 850 nm to 950 nm, which is necessary for next-generation high-speed data communications.
Innovation Solution
A method that uses DMD measurement data from a single wavelength to predict and assess EMB at other wavelengths through linear transformations of ROD and ROB data, allowing for the computation of effective bandwidth without the need for extensive measurements at each wavelength, thereby reducing production costs and time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EMB measurements are performed at multiple wavelengths to qualify wide-band multimode fiber performance, then measurement accuracy and reliability are improved, but measurement time and production cost increase significantly
Solution Approach 1:
The patent performs DMD measurements at a reference wavelength (850 nm) in advance to establish ROD and ROB data, which are then transformed to predict EMB at other wavelengths (e.g., 950 nm). This preliminary characterization at one wavelength enables subsequent wavelength predictions without additional time-consuming measurements, resolving the contradiction between measurement reliability and time consumption.
Solution Approach 2:
The patent creates a mathematical model (copy) of the fiber's modal dispersion characteristics through DMD measurements at a reference wavelength. This model is then used to predict performance at other wavelengths, replacing the need for actual physical measurements at each wavelength while maintaining qualification accuracy.
2Measurement precision
If DMD measurements are performed at each wavelength point to assess EMB, then measurement precision is improved, but device complexity and operational difficulty increase
Solution Approach 1:
The patent develops a universal measurement approach where DMD measurements at a single reference wavelength serve multiple purposes: directly characterizing fiber performance at that wavelength and predicting performance at all other wavelengths in the operational range. This multi-functional approach eliminates the need for separate measurement systems at each wavelength, reducing device complexity while maintaining precision.
Solution Approach 2:
The patent transforms the measurement approach by changing from direct EMB measurement at each wavelength to measuring DMD parameters (ROD and ROB) at a reference wavelength, then mathematically transforming these parameters to predict EMB at other wavelengths. This parameter transformation approach simplifies the measurement system while preserving assessment precision.
3Productivity
If traditional single-wavelength EMB assessment is used, then production efficiency is improved, but adaptability to wide-band applications deteriorates
Solution Approach 1:
The patent extends the qualification capability from a single wavelength dimension to a multi-wavelength dimension by introducing wavelength as an additional parameter in the prediction model. The DMD data at reference wavelength serves as a basis for predicting EMB across the entire wide-band wavelength range (850-950 nm), enabling high-speed VCSEL applications without sacrificing production efficiency.
Data Source
Figure 1~2
Figure 3a~3d
Figure 4~6
AI summary
The present disclosure concerns a method of qualifying an effective bandwidth of a multimode optical fiber at a first wavelength λ1; using DMD data of the fiber measured a second wavelength λ2. Data representative of a Radial Offset Delay, a Radial Offset Bandwidth and a Relative Radial Coupled Power of the fiber are derived from the DMD data at the second wavelength λ2. A transformation is performed on the ROD data and ROB data at the second wavelength λ2 to obtain corresponding ROD data and ROB data at the first wavelength λχ. An effective bandwidth of the fiber at the second wave- length λ2 is computed using the ROD data and the ROD data at the first wavelength λ1 and the P DMD data at the second wavelength λ2.