Pluggable Fiber Loopback Apparatus With Thin-Film Attenuation

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Solution Overview

Problem

Fiber-based loopback apparatuses have limitations in attenuation range, are expensive, and restrict the ability to perform comprehensive optical signal performance evaluations due to restricted choices of attenuation fibers, especially for multimode fibers.

Innovation Solution

A pluggable loopback apparatus using a thin-film filter in the optical path to provide selective attenuation, allowing for arbitrary amounts of optical signal attenuation and enabling broader signal management capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If attenuation fiber is used to provide optical attenuation, then a select amount of attenuation can be achieved, but the attenuation range is relatively narrow and the cost is high

Engineering Contradiction:

Improveattenuation capabilityVSAvoidattenuation range

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent changes the fundamental parameter of attenuation implementation from fiber doping concentration and length to thin-film filter optical density and wavelength characteristics. This allows continuous adjustment of attenuation values across a broad range by selecting different filter specifications, resolving the contradiction between reliable attenuation and limited attenuation range.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent substitutes the mechanical/optical system of attenuation fiber (relying on physical fiber length and doping) with an optical filtering system using thin-film filters. This substitution enables broader attenuation ranges and lower costs while maintaining reliable attenuation performance.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If attenuation fiber is used to provide optical attenuation, then a select amount of attenuation can be achieved, but the cost is high

Engineering Contradiction:

Improveattenuation capabilityVSAvoidcost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive attenuation fiber with relatively inexpensive thin-film filter components. The thin-film filters can be manufactured at lower cost using standard optical coating techniques, significantly reducing the overall system cost while maintaining reliable attenuation capability.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent substitutes the expensive attenuation fiber manufacturing process with a more cost-effective thin-film filter fabrication process, achieving the same functional result at lower cost.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If attenuation fiber is used, then optical signals can be attenuated, but mode distortion occurs and other signal performance evaluations are limited

Engineering Contradiction:

Improveattenuation functionVSAvoidmode distortion

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent substitutes attenuation fiber with thin-film filters that attenuate optical signals without introducing mode distortion. The thin-film filters work by wavelength-selective absorption or reflection rather than physical fiber propagation, eliminating the harmful mode distortion effect while maintaining the attenuation function.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces thin-film filters as an intermediary component between the optical signal source and detector, providing attenuation without the harmful side effects of attenuation fiber. The filter acts as a mediator that achieves the desired attenuation while preserving signal integrity.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution provides flexible and cost-effective attenuation, avoiding mode distortion and enabling both power and spectral filtering, thus enhancing the evaluation and management of fiber optical systems.

Implementation Method 1

a thin-film filter disposed in the optical path and configured to provide a select amount of attenuation for light traveling over the optical path

Methodology Applied

Scientific EffectThin-film filtering: Filter (optical)

Data Source

PatentUS10330868B2Pluggable fiber loopback apparatus and methods for fiber optical systems

Publication Date: 2019.06.25 ALLIAN FIBER OPTIC PROD INC

AI summary

The loopback apparatus disclosed herein is used with an optical fiber system having an optical fiber cable. The loopback apparatus includes an optical fiber having input and output ends and an output optical fiber having input and output ends. The loopback apparatus also includes an optical system that defines an optical path and that is configured to optically couple the output end of the input optical fiber with the input end of the output optical fiber over the optical path. The loopback apparatus also includes a thin-film filter disposed in the optical path and configured to provide a select amount of attenuation for light traveling over the optical path. The loopback apparatus can be plugged into and unplugged from the optical fiber cable. Loopback methods for measuring the performance of the optical fiber system using the loopback apparatus are also disclosed.