Multimode Launch System for Automated OTDR Fiber Testing

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Solution Overview

Problem

Existing methods for performing OTDR measurements on multimode multi-fiber array devices lack automation and compliance with modal distribution requirements, leading to unrepeatable results and component wear issues.

Innovation Solution

A system utilizing a conventional optical switch with a multi-fiber mode conditioner and an optical switch characterized by enhanced guidance parameters, along with a mode filter and angle-polished connectors, to ensure mode-conditioned test light distribution and extend component lifespan.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If a conventional optical switch is used to automate OTDR measurements on multi-fiber array DUT, then automation is achieved, but modal distribution requirements are not maintained leading to unrepeatable results

Engineering Contradiction:
Improveautomation of OTDR measurementsVSAvoidrepeatability of measurement results
Core Design Contradiction:
Extent of automationVSMeasurement precision

Solution Approach 1:

A mode conditioner is introduced as an intermediary component between the optical switch and the multi-fiber array DUT. This mode conditioner actively manages and conditions the modal distribution of test light, ensuring that even though automation is provided by the optical switch, the measurement repeatability is maintained through proper mode conditioning of the test signal before it enters the DUT.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If manual sequential measurement is performed on each fiber path, then modal distribution control is maintained, but measurement time increases significantly

Engineering Contradiction:
Improvemodal distribution controlVSAvoidmeasurement time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent combines multiple functions into a single integrated measurement system. The optical switch enables simultaneous access to multiple fiber paths, while the mode conditioner maintains proper modal distribution across all paths. This merging of automation capability with mode conditioning allows all fiber paths to be measured in parallel rather than sequentially, dramatically reducing measurement time while maintaining precision.

Inventive Principle:
Principle #5Merging (Combining)

3Extent of automation

If conventional optical switches are used for automated measurement, then measurement automation is achieved, but component lifespan is reduced due to increased wear

Engineering Contradiction:
Improveautomation capabilityVSAvoidcomponent lifespan
Core Design Contradiction:
Extent of automationVSDuration of action of stationary object

Solution Approach 1:

The patent employs angle-polished connectors which are designed to minimize Optical Return Loss and are easier to replace or re-polish compared to conventional connectors. This approach accepts that automated measurement components may have reduced lifespan but mitigates the impact by using cheaper, more easily maintained connector types, reducing overall system cost and downtime.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

4Measurement precision

If mode conditioner is added to maintain modal distribution, then measurement repeatability is improved, but system complexity increases

Engineering Contradiction:
Improvemeasurement repeatabilityVSAvoidsystem component count
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The mode conditioner is designed to work universally with the optical switch and multi-fiber array DUT configuration. It performs multiple functions: conditioning the modal distribution, adapting to different fiber paths through the optical switch, and maintaining compatibility with angle-polished connectors. This multi-functionality justifies the added component by providing comprehensive control over modal distribution across the entire automated measurement system.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

The system automates OTDR measurements on all fiber paths while maintaining compliance with modal distribution requirements, reducing biases and extending the life of test components by minimizing Optical Return Loss.

Implementation Method 1

A conventional optical switch between the launch cord and the multi-fiber array DUT may be used to automate the OTDR measurements

Methodology Applied
Scientific EffectOptical fiber guidance: Optical Fibre

Implementation Method 2

angle-polished connectors, to ensure mode-conditioned test light distribution and extend component lifespan

Methodology Applied
Scientific EffectReflection reduction through angle polishing: Reflection

Data Source

PatentEP3144659B1Multimode launch systems for use in performing an OTDR measurement on a multi-fiber array DUT and method of performing same
Publication Date: 2020.04.01 EXFO
  • EP3144659B1 patent drawingFigure 1~2
  • EP3144659B1 patent drawingFigure 3~3A
  • EP3144659B1 patent drawingFigure 4

AI summary

A multimode launch system to be connected to an Optical Time-Domain Reflectometer (OTDR) for use in performing at least one OTDR measurement on a multi-fiber array Device Under Test (DUT), the multimode launch system comprising: an optical switch being connectable to the OTDR during use; a launch array device having an end being connectable to the optical switch and another end being connectable to the multi-fiber array DUT during use, the launch array device having a plurality of multimode launch optical fibers each having at least one first guidance parameter being smaller than a corresponding one of at least one second guidance parameter of at least one multimode optical fiber of the optical switch; and a multi-fiber mode conditioner along the launch array device for inducing a preferential attenuation of higher-order optical modes of test light propagated into the multi-fiber array DUT during use.