Optical Fiber Random Lasers for Phase-Sensitive Reflectometry

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Solution Overview

Problem

Conventional phase-sensitive and polarization optical time-domain reflectometries face challenges in ensuring measurement accuracy and extending sensing distance due to high noise, optical fiber loss, and limited spatial resolution, particularly with first-order distributed Raman amplification technologies.

Innovation Solution

The implementation of a long-distance polarization and phase-sensitive optical time-domain reflectometry using optical fiber random lasers as a distributed pump source, which includes a laser, acousto-optic modulator, erbium-doped fiber amplifier, circulator, fiber Bragg gratings, and a photoelectric detector array, to achieve low-noise distributed amplification and extended sensing distance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If conventional first-order distributed Raman amplification technology is used, then spatial distribution uniformity of optical signals is improved, but relative intensity noise of the Raman pump source becomes large and restricts sensing distance extension

Engineering Contradiction:

Improvespatial distribution uniformityVSAvoidmeasurement accuracy

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent changes the fundamental parameter of the pump source from conventional Raman lasers to optical fiber random lasers. This parameter change transforms the noise characteristic from high RIN (>-100 dBc/Hz) to low noise operation, enabling both spatial uniformity and extended sensing distance without the noise limitations of conventional Raman amplification

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs optical fiber random lasers which have a simple structure and low cost compared to conventional Raman pump sources. The random laser approach uses distributed Rayleigh scattering in the fiber itself as the gain medium, eliminating the need for complex external pump lasers and making the system more economical and reliable for long-distance sensing

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Measurement precision

If signal light power peak is increased to improve measurement accuracy, then unstable modulation and self-phase modulation occur causing frequency spectrum broadening

Engineering Contradiction:

Improvemeasurement accuracyVSAvoidsignal stability

Core Design Contradiction:

Measurement precisionVSStability of the object's composition

Solution Approach 1:

The patent introduces distributed Raman amplification as an intermediary mechanism along the optical fiber. This distributed amplification compensates for signal loss continuously throughout the fiber length, allowing the use of lower peak power pulses that maintain signal stability while still achieving high measurement accuracy through the accumulated amplification effect along the transmission path

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If pulse width is narrowed to increase spatial resolution, then energy carried by signal pulse decreases resulting in decreased measurement accuracy

Engineering Contradiction:

Improvespatial resolutionVSAvoidmeasurement accuracy

Core Design Contradiction:

Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The patent implements continuous distributed Raman amplification along the optical fiber transmission path. This continuous amplification compensates for the energy loss of narrow pulses as they propagate, maintaining the pulse energy required for accurate measurement throughout the entire sensing distance while preserving the narrow pulse width needed for high spatial resolution

Inventive Principle:

Principle #20Continuity of useful action

4Length of stationary object

If sensing distance is extended, then optical fiber loss and pump consumption affect measurement resolution of the optical fiber back-end

Engineering Contradiction:

Improvesensing distanceVSAvoidmeasurement resolution

Core Design Contradiction:

Length of stationary objectVSMeasurement precision

Solution Approach 1:

The patent divides the optical fiber into distributed segments along its length, with Raman amplification occurring continuously at multiple points throughout the fiber. This segmentation approach prevents signal degradation at any single location and maintains measurement resolution across the entire extended sensing distance by providing localized amplification throughout the transmission path

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS9163960B2Long-distance polarization and phase-sensitive optical time-domain reflectometry based on random laser amplification

Publication Date: 2015.10.20 UNIV OF ELECTRONICS SCI & TECH OF CHINA

AI summary

A long-distance polarization and phase-sensitive reflectometry based on random laser amplification for extending a sensing distance includes a long-distance polarization and phase-sensitive reflectometry of a distributed Raman amplification based on optical fiber random lasers generated by unilateral pumps, a long-distance polarization and phase-sensitive reflectometry of a distributed Raman amplification based on optical fiber random lasers generated by bilateral pumps, and a long-distance polarization and phase-sensitive reflectometry of a Raman amplification based on a combination of optical fiber random lasers generated by unilateral pumps and a common Raman pump source, which are applied in optical fiber perturbation sensing and have a capability of greatly improving a working distance of a sensing system and a high practicability.