Optical Fiber Characteristic Measurement With Giant-Pulse Prevention

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Solution Overview

Problem

Existing optical fiber characteristic measurement methods face challenges in improving measurement accuracy while preventing the occurrence of giant pulses that can damage optical detectors due to excessive optical power during amplification of pump or return light.

Innovation Solution

The method involves superimposing first superimposition light on pump light before amplification, using a filter to attenuate components of the superimposition light in return light, and controlling the intensity of the superimposition light to prevent excessive population inversion in optical amplifiers, thereby preventing giant pulses and enhancing measurement accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If pump light or return light is amplified by an optical amplifier to increase detection intensity, then measurement accuracy is improved, but a giant pulse may occur that can destroy an optical detector

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidgiant pulse occurrence
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by superimposing a DC component light beam onto the pump light beam before amplification. This pre-conditioning of the light beam prevents excessive population inversion in the optical amplifier, thereby preventing giant pulse occurrence while still allowing sufficient amplification to improve measurement accuracy of the fiber under test

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent changes the parameter composition of the pump light by adding a DC component light beam with a different wavelength. This parameter change modifies the amplification characteristics in the optical amplifier, enabling higher gain without triggering giant pulses, thus resolving the contradiction between measurement accuracy and giant pulse prevention

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If the gain of pump light in the optical amplifier is increased to improve measurement accuracy, then detection intensity is improved, but the frequency of giant pulse occurrence increases

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidfrequency of giant pulse occurrence
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

By superimposing the DC component light beam onto the pump light beam before amplification, the patent pre-prevents excessive population inversion. This allows the system to operate at higher gain settings for improved measurement accuracy while maintaining reliability by preventing giant pulse occurrence through the preliminary modification of the light beam characteristics

Inventive Principle:
Principle #10Preliminary action

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

This approach increases the measurement accuracy of optical fiber characteristics by preventing giant pulses, allowing for higher gain without damaging detectors, and relaxes limitations on fiber length and measurement precision.

Implementation Method 1

amplifying the pump light to be input into the fiber under test

Methodology Applied
Scientific EffectOptical amplification:

Implementation Method 2

a filter configured to attenuate a component of the first superimposition light contained in at least one of the amplified light or the return light

Methodology Applied
Scientific EffectOptical filtering: Filter (optical)

Implementation Method 3

a circulator configured to cause amplified light output from the pump light amplifier to be incident on a first end of a fiber under test, and configured to take out return light from the fiber under test

Methodology Applied
Scientific EffectOptical circulation:

Data Source

PatentEP4617637A1Optical fiber characteristic measurement apparatus and optical fiber characteristic measurement method
Publication Date: 2025.09.17 YOKOGAWA ELECTRIC CORP
  • EP4617637A1 patent drawingFigure 1
  • EP4617637A1 patent drawingFigure 2
  • EP4617637A1 patent drawingFigure 3

AI summary

An optical fiber characteristic measurement apparatus (10) includes a first light source (13) configured to emit first superimposition light to be superimposed on pump light, a pump light amplifier (15) configured to amplify light in which the pump light and the first superimposition light are combined, a circulator (24) configured to cause amplified light output from the pump light amplifier (15) to be incident on a first end of a fiber under test (80) and configured to take out return light from the fiber under test (80), a filter (16) configured to attenuate a component of the first superimposition light contained in at least one of the amplified light or the return light, and a measurement unit (43) configured to measure the characteristic of the fiber under test (80) by detecting the return light.