Multi-Wavelength DMD Measurement for Optical Fiber Bandwidth
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Solution Overview
Problem
Current methods for measuring the bandwidth of optical multimode and few-mode fibers are limited to a single wavelength, such as 850 nm, and are not suitable for emerging applications requiring testing at higher wavelengths, and they lack the capability to evaluate fiber performance across a wide range of wavelengths.
Innovation Solution
A differential mode delay measurement system that uses a tunable single mode laser capable of generating light waves across a range of 600 to 1700 nm, combined with a pulse generator and modulator to produce a modulated optical test signal, allowing for bandwidth evaluation at multiple wavelengths using bit error rate testing equipment with high time resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a short pulsed laser is employed to transmit the light signal through the MMF or FMF, then the bandwidth measurement can be performed, but the measurement is limited to one wavelength around 850 nm
Solution Approach 1:
The patent employs a tunable laser source that can operate across multiple wavelengths (600-1700 nm range), allowing the same measurement system to perform bandwidth measurements at different wavelengths without requiring separate specialized equipment for each wavelength, thus achieving multi-functionality
Solution Approach 2:
The patent changes the wavelength parameter of the light source by using a tunable laser that can be adjusted across a broad spectrum range. This allows the measurement system to adapt to different wavelength requirements by simply tuning the laser wavelength rather than changing the entire measurement apparatus
2Adaptability or versatility
If Ti-sapphire lasers are employed to achieve multiple wavelengths, then wavelength versatility is improved, but the system becomes expensive and difficult to maintain
Solution Approach 1:
The patent replaces expensive, complex Ti-sapphire lasers with more affordable, commercially available tunable laser sources that have simpler maintenance requirements. While the laser has a limited lifetime like any optical component, its lower cost and simpler structure make it a practical replacement for high-maintenance Ti-sapphire systems
Solution Approach 2:
The patent substitutes the complex mechanical and optical alignment systems of Ti-sapphire lasers with electronically controlled tunable laser sources that achieve wavelength tuning through electrical signals rather than mechanical adjustment, reducing maintenance complexity
3Measurement precision
If offset launch method is used to measure bandwidth, then measurement can be performed, but the process requires varying offset across the face of the fiber and complex data processing
Solution Approach 1:
The patent performs preliminary calibration by establishing the relationship between launch offset and mode excitation before actual measurements. This pre-characterization allows for simplified measurement procedures where the calibrated offset relationships can be directly applied without requiring complex real-time adjustments during measurement
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 accurate and reliable bandwidth measurement of optical fibers at various wavelengths, improving the accuracy and reliability of fiber characterization and enabling testing across multiple wavelengths without equipment adjustments, thus addressing the limitations of existing single-wavelength measurement systems.
Implementation Method 1
The modulator is configured to generate a modulated optical test signal through the optical fiber based at least in part on the received light wave and pulse train signals
Implementation Method 2
transmitting the modulated optical test signal through an optical test fiber
Data Source
AI summary
A differential mode delay (DMD) measurement system for an optical fiber is provided. The system includes an optical test fiber with a plurality of modes; a single mode light source that provides a continuous light wave signal to a modulator; and a pulse generator that provides an electrical pulse train signal to the modulator and a triggering signal to a receiver. The modulator is configured to generate a modulated optical test signal through the optical fiber based at least in part on the received light wave and pulse train signals, and the receiver is configured to receive the test signal transmitted through the fiber and evaluate the test signal based at least in part on the triggering signal. The system can be employed to create DMD waveform and centroid charts to obtain minEMBc bandwidth information for a fiber within a wavelength range.