Optical Link Characterization Using EMBW and ISI Penalty
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Solution Overview
Problem
Existing multi-mode fiber optical links are restricted by conservative IEEE measurements, limiting their use beyond specified distances for certain communications protocols, and preventing the upgrade of legacy systems with longer fibers to newer protocols like 10GBASE-SR.
Innovation Solution
A fiber link estimator system that determines the effective modal bandwidth (EMBW) and intersymbol interference (ISI) penalty of optical links using a semiconductor laser-generated signal, allowing characterization and validation of fibers for use with specific protocols, even if they exceed the IEEE-specified maximum lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conservative IEEE measurements are used to specify maximum fiber lengths for communications protocols, then link reliability is ensured, but the usable distance and adaptability of optical links are limited
Solution Approach 1:
The patent changes the characterization parameters from conservative distance-based specifications to performance-based metrics (EMBW and ISI penalty). By measuring actual link performance parameters rather than relying on conservative distance thresholds, the system enables protocol adaptation for links that exceed traditional length limits while maintaining reliability through quantitative performance validation.
2Reliability
If IEEE-specified maximum lengths are enforced for optical links, then protocol compatibility is guaranteed, but legacy systems with longer fibers cannot be upgraded to newer protocols
Solution Approach 1:
The patent performs preliminary characterization of the optical link by measuring EMBW and ISI penalty before protocol deployment. This advance performance assessment allows legacy systems with longer fibers to be validated for newer protocols like 10GBASE-SR before upgrade, enabling productive system evolution while maintaining compatibility through performance-based verification.
3Ease of manufacture
If fixed distance limitations are imposed on multi-mode fiber links, then protocol compliance is simplified, but the effective utilization of existing fiber infrastructure is reduced
Solution Approach 1:
The patent replaces the mechanical/installation-based compliance approach (enforcing fixed distance limits during deployment) with a measurement-based validation system. By substituting physical constraints with electronic/optical performance measurements (EMBW and ISI penalty analysis), the system achieves protocol compliance through characterization rather than constraint, thereby maximizing fiber infrastructure utilization.
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 the reliable assessment and validation of optical links for use with specific protocols, allowing legacy systems to be upgraded to 10GBASE-SR, even if fibers are longer than the IEEE-specified maximum, by determining if the EMBW and ISI penalty meet predetermined threshold values.
Implementation Method 1
transmitting a semiconductor laser-generated optical signal from a first end of a multi-mode fiber (MMF) optical link
Implementation Method 2
converting the optical signal to an electrical signal
Data Source
AI summary
Various example embodiments are disclosed. According to one example embodiment, a method may include transmitting a semiconductor laser-generated optical signal from a first end of a multi-mode fiber (MMF) optical link to a second end of the link. The optical signal may have a reference bandwidth at the first end of the link. The method may further include converting the optical signal to an electrical signal. The method may further include analyzing the electrical signal with an electronic dispersion compensator to determine an effective modal bandwidth (EMBW) of the received optical signal. The method may further include analyzing the electrical signal with an electronic dispersion compensator to determine an intersymbol interference (ISI) penalty of the optical link. The method may further include comparing the EMBW and the ISI penalty to predetermined threshold values of a tolerable EMBW and a tolerable ISI penalty, respectively, to characterize the optical link as acceptable or unacceptable for use as a communications link with a predetermined communications protocol.