Mode-Selective Brillouin Amplification for Rayleigh Backscatter Testing

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing optical pulse test methods face challenges in amplifying desired propagation modes of backscattered light in optical fibers with multiple propagation modes using stimulated Brillouin scattering, as the amplification gain varies depending on the interacting modes, making it unclear how to achieve desired amplification in two-mode regions of few-mode optical fibers and general single-mode fibers.

Innovation Solution

A backscattered light amplification device and method that control the power, incident timing, and pulse width of pump pulses for each propagation mode, generating a Brillouin gain spectrum to achieve desired amplification gains for specific modes of backscattered light, using a probe pulse and pump pulses with controlled power ratios, pulse lengths, and time differences to selectively amplify desired propagation modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If stimulated Brillouin scattering is used to amplify backscattered light in a fiber with multiple propagation modes, then the amplification gain varies depending on the interacting modes, but it becomes unclear how to achieve desired amplification for specific modes

Engineering Contradiction:

Improveamplification gain controlVSAvoidmode-selective amplification control

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The pump light is segmented into multiple propagation modes (LP01 mode and LP11 mode) with independent control capabilities. Each mode component can be individually adjusted in terms of power, pulse width, and incident timing, allowing selective amplification of desired backscattered light modes while suppressing others

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically controls the pump pulse parameters (power, pulse width, incident timing) for each propagation mode based on the desired amplification characteristics. The control unit adjusts these parameters in real-time to achieve mode-selective amplification, making the amplification process adaptive and controllable

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If pump light is incident in multiple propagation modes to amplify backscattered light, then arbitrary Brillouin amplification gains can be achieved, but the device complexity increases due to need for individual control of power, incident timing, and pulse width for each mode

Engineering Contradiction:

Improvearbitrary amplification gainVSAvoidcontrol system complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The pump light source system is designed with multi-functionality to generate pump light in multiple propagation modes (LP01 and LP11 modes) simultaneously. A single pump light source unit performs multiple functions: generating base pump light, dividing it into different modes, and independently controlling each mode's parameters, thereby reducing the need for separate light sources for each mode

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

A control unit acts as an intermediary between the operator and the complex pump pulse parameters. This control unit receives input signals and automatically adjusts the power, pulse width, and incident timing of pump pulses for each propagation mode, simplifying the operation while achieving arbitrary amplification gains

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

This approach allows for arbitrary Brillouin amplification gains to be applied to desired propagation modes of backscattered light, enabling effective amplification of Rayleigh backscattered light with precise control, thereby overcoming the variability in amplification gains across different propagation modes.

Implementation Method 1

amplifying distributedly in FUT backscattered light generated by a probe pulse propagating in FUT using pump light having a frequency (short wavelength) higher by the Brillouin frequency shift

Methodology Applied

Scientific EffectStimulated Brillouin scattering: Brillouin Scattering

Implementation Method 2

acquires distribution data (OTDR waveform) based on intensity and round trip time of backscattered light of Rayleigh scattered light derived from a test light pulse

Methodology Applied

Scientific EffectRayleigh scattering: Rayleigh Scattering

Data Source

PatentUS11802809B2Backscattering optical amplification device, optical pulse testing device, backscattering optical amplification method and optical pulse testing method

Publication Date: 2023.10.31 NIPPON TELEGRAPH & TELEPHONE CORP

AI summary

The present invention is to provide a backscattered light amplification device, an optical pulse test apparatus, a backscattered light amplification method, and an optical pulse test method for amplifying a desired propagation mode of Rayleigh backscattered light with a desired gain by stimulated Brillouin scattering in a fiber under test having the plurality of propagation modes. The backscattered light amplification device according to the present invention is configured to control individually power, incident timing, and pulse width of a pump pulse for each propagation mode when the pump pulse is incident in a plurality of propagation modes after the probe pulse is input to the fiber under test in any propagation mode.