Single-Unit Multi-Span DAS Interrogator With Wavelength Merging

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Solution Overview

Problem

Conventional distributed acoustic sensing (DAS) systems require multiple interrogator units at different wavelengths to sense multiple spans, adding structural and operational complexity and increasing error rates, particularly in the presence of optical amplifiers.

Innovation Solution

A single DAS interrogator unit with multiple wavelength/multiple frequency components is used to perform multi-span sensing, reducing complexity and cost by eliminating the need for synchronized circuits and allowing efficient monitoring of extended DAS ranges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If multiple DAS interrogator units operating at different wavelengths are used to sense different portions of optical fiber, then the sensing coverage is improved, but the device complexity and error rate increase

Engineering Contradiction:
Improvesensing coverageVSAvoiddevice complexity
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The patent combines multiple wavelength sensing capabilities into a single DAS interrogator unit. The system uses a single interrogator that transmits multiple wavelengths simultaneously or sequentially, eliminating the need for multiple separate interrogator units while maintaining comprehensive sensing coverage across multiple fiber spans.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single DAS interrogator unit is designed to perform multiple functions by operating at different wavelengths. It can sense different portions of the optical fiber using wavelength division multiplexing, making one device universal for multi-span sensing instead of requiring specialized interrogators for each span.

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

2Length of stationary object

If multiple DAS interrogator units are deployed to monitor extended DAS ranges, then the measurement coverage is improved, but the operational complexity and synchronization requirements increase

Engineering Contradiction:
Improvemeasurement coverageVSAvoidoperational complexity
Core Design Contradiction:
Length of stationary objectVSEase of operation

Solution Approach 1:

The patent merges the functionality of multiple interrogator units into a single device that can monitor extended DAS ranges. By integrating multiple wavelength channels and sensing capabilities into one unit, the system eliminates synchronization complexity between multiple independent interrogators while maintaining comprehensive measurement coverage.

Inventive Principle:
Principle #5Merging (Combining)

3Length of stationary object

If conventional DAS systems use multiple interrogator units to sense multiple spans, then the sensing range is extended, but the structural complexity and cost increase

Engineering Contradiction:
Improvesensing rangeVSAvoidstructural complexity
Core Design Contradiction:
Length of stationary objectVSDevice complexity

Solution Approach 1:

The patent combines multiple sensing functions and wavelength channels into a single integrated DAS interrogator unit, thereby extending the sensing range to multiple spans without requiring multiple separate interrogator structures. This integration reduces both structural complexity and associated costs.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single interrogator unit is designed with universal multi-functionality to handle multiple fiber spans through wavelength division multiplexing. It can simultaneously or sequentially sense different spans using different wavelengths, eliminating the need for multiple specialized interrogators and reducing overall system structural complexity.

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 solution enables efficient, cost-effective monitoring of multiple spans in optical communication systems, including undersea environments, by reducing complexity and error rates while extending the DAS range to detect seismic and other disturbances.

Implementation Method 1

the DAS system may be based on Rayleigh backscattering (otherwise referred to as a Rayleigh-scattering-based DAS system). In this system, a coherent laser pulse may be sent along an optical fiber, and scattering sites within the optical fiber may cause the fiber to act as a distributed interferometer

Methodology Applied
Scientific EffectRayleigh backscattering: Rayleigh Scattering

Implementation Method 2

a coherent laser pulse may be sent along an optical fiber

Methodology Applied
Scientific EffectCoherent light: Coherent Light

Implementation Method 3

modulating one or more optical signals using one or more measurement pulses and generating one or more modulated optical signals

Methodology Applied
Scientific EffectOptical modulation: Phase Modulation

Data Source

PatentEP4621364A1Interrogator unit for multi-span distributed acoustic sensing
Publication Date: 2025.09.24 SUBCOM LLC
  • EP4621364A1 patent drawingFigure 1
  • EP4621364A1 patent drawingFigure 2a
  • EP4621364A1 patent drawingFigure 2b

AI summary

An optical communication system and a method. The system includes a distributed acoustic sensing (DAS) interrogation unit. The DAS interrogation unit is configured to generate one or more optical signals for determining a status of one or more portions of an optical communication path, modulate one or more optical signals using one or more measurement pulses and generate one or more modulated optical signals, and transmit one or more modulated optical signals to the one or more portions of the optical communication path. The status of one or more portions of the optical communication path is determined based on one or more reflected signals reflected by one or more portions of the optical communication path in response to one or more modulated optical signals.