JP-2026075064-A - Acoustic sensing for multispan sensing using single-wavelength optical frequency domain reflection method

Abstract

[Problem] To disclose an acoustic sensing method for multispan sensing using a single-wavelength optical frequency domain reflection method. [Solution] A system and method for monitoring an optical transmission path in an optical transmission system. The optical transmission system comprises a sensing and interrogation unit and a plurality of sensing units located on the optical transmission path. An optical signal is transmitted to the plurality of sensing units to determine the state of one or more portions of the optical transmission path. A plurality of reflected signals in response to the optical signal are received. The plurality of reflected signals are converted in at least one of the frequency domain and the time domain. The state of one or more portions is determined using the converted plurality of reflected signals. [Selection Diagram] Figure 4a

Inventors

• カイ ジン－シン
• フィリペッツキー エヌ アレクセイ

Assignees

• サブコム，エルエルシー

Dates

Publication Date

20260507

Application Date

20251003

Priority Date

20241021

Claims (20)

1. Interrogation and sensing unit, The system comprises a plurality of sensing units located in the aforementioned interrogation and sensing unit and communicably coupled to the aforementioned interrogation and sensing unit using an optical communication path, The aforementioned interrogation and sensing unit is In order to determine the state of one or more parts of the optical communication path, optical signals are transmitted to the plurality of sensing units. Multiple reflected signals are received in response to the aforementioned optical signal. The plurality of reflected signals are converted in at least one of the frequency domain and the time domain, The system is configured to determine the state of one or more parts using a plurality of converted reflected signals. Optical communication system.
2. The aforementioned optical signal is a single-wavelength optical signal. The optical communication system according to claim 1.
3. In order to determine one or more positions corresponding to the approximate positions of the reflected signals included in the plurality of reflected signals in the optical communication path, the plurality of reflected signals are converted in the frequency domain. The optical communication system according to claim 1.
4. The plurality of reflected signals converted in the frequency domain are, To determine one or more changes in the reflected signal over a predetermined time period, and to determine the precise position of the reflected signal, The transformation in the aforementioned time domain The optical communication system according to claim 3.
5. The transformation of the reflected signal in the frequency domain and the time domain is performed by the Fast Fourier Transform. The optical communication system according to claim 4.
6. The plurality of reflected signals include at least a portion of the first plurality of reflected signals received in a first time period and at least a portion of the second plurality of reflected signals received in a second time period, wherein the second time period is a time period following the first time period. The optical communication system according to claim 3.
7. The interrogation and sensing unit includes a transmission optical device configured to transmit the optical signal to the plurality of sensing units. The optical communication system according to claim 1.
8. The optical transmission device includes a laser light source configured to generate the optical signal, The optical communication system according to claim 7.
9. The laser light source includes at least one of a scanning laser, a continuous wave laser, a multi-tone frequency laser, and any combination thereof. The optical communication system according to claim 8.
10. The interrogation and sensing unit includes a receiving optical device configured to be communicatively coupled to the optical transmission path and to receive the plurality of reflected signals. The optical communication system according to claim 1.
11. The optical communication path is a distributed acoustic sensing optical transmission path. The optical communication system according to claim 1.
12. The optical signal includes an interrogation signal. The optical communication system according to any one of claims 1 to 11.
13. A method for monitoring an optical transmission path in an optical transmission system comprising an interrogation and sensing unit and a plurality of sensing units located on the optical transmission path, To determine the state of one or more parts of the optical communication path, optical signals are transmitted to the plurality of sensing units. Receiving multiple reflected signals in response to the aforementioned optical signal, Converting the plurality of reflected signals in at least one of the frequency domain and the time domain, This includes determining the state of one or more parts using the converted multiple reflected signals, A method for monitoring optical transmission paths in an optical transmission system.
14. The aforementioned optical signal is a single-wavelength optical signal. The method according to claim 13.
15. In order to determine one or more positions corresponding to the approximate positions of the reflected signals included in the plurality of reflected signals in the optical communication path, the plurality of reflected signals are converted in the frequency domain. The method according to claim 13.
16. The plurality of reflected signals converted in the frequency domain are, To determine one or more changes in the reflected signal over a predetermined time period, and to determine the precise position of the reflected signal, The transformation in the aforementioned time domain The method according to claim 15.
17. The transformation of the reflected signal in the frequency domain and the time domain is performed by the Fast Fourier Transform. The method according to claim 16.
18. The plurality of reflected signals include at least a portion of the first plurality of reflected signals received in a first time period and at least a portion of the second plurality of reflected signals received in a second time period, wherein the second time period is a time period following the first time period. The method according to claim 15.
19. The aforementioned interrogation and sensing unit is A transmission optical device configured to transmit the optical signal to the plurality of sensing units, Includes a receiving optical device configured to be communicatively coupled to the optical transmission path and to receive the plurality of reflected signals, The method according to any one of claims 13 to 18.
20. The transmission optical device includes a laser light source configured to generate the optical signal, the laser light source includes at least one of a scanning laser, a continuous wave laser, a multitone frequency laser, and any combination thereof. The method according to claim 19.

Description

This disclosure generally relates to optical fiber communication systems, particularly distributed acoustic sensing, and more specifically, to distributed acoustic sensing for multispan sensing using a single-wavelength optical frequency domain reflection method. Distributed acoustic sensing (DAS), which uses telecommunications optical fibers as distributed sensors, is used to continuously detect spatial interference in real time along one or more long-distance transmission/sensing optical fibers. Conventional DAS distributed sensing systems are limited to performing sensing over optical fiber lengths of approximately 50–100 km (e.g., extended to 150 km in research units for available products). Such systems typically include a DAS interrogator unit (IU), which includes a DAS transmitter, a DAS receiver, and one or more repeater erbium-doped fiber amplifiers (EDFAs) that can be used to amplify one or more signals transmitted to the IU. However, conventional systems cannot sense multispan links using such series amplifiers. Some conventional systems use multiple DAS units operated at different wavelengths. Alternatively, wavelength-related optical loopback paths are used to sense span, and optical bandpass filters are used for filtering and/or selecting specific wavelengths for reverse transmission. This makes submarine optical path systems using the above sensing techniques more expensive, and because most repeaters are sole, it is difficult to remember backup units. For example, a DAS system may be based on Rayleigh backscattering (also called a Rayleigh scattering-based DAS system). In this system, a coherent laser pulse can be transmitted along an optical fiber, and due to the scattering sites within the optical fiber, the optical fiber can function as a dispersive interferometer, for example, its gauge length being approximately equal to the pulse length. The intensity, frequency, and/or phase of any reflected light can be measured as a function of time after the laser pulse has been transmitted; this is called a coherent optical time-domain reflectometer (COTDR). In some conventional systems, telecommunications optical fibers are used as distributed sensors to continuously and in real time detect spatial interference along long-distance transmission/sensing optical fibers. However, typical sensing systems generally require multiple distributed acoustic sensing interrogation units operating at different wavelengths to sense different parts of the optical fiber. Especially when there are interfering elements along the cable (e.g., optical amplifiers), the sensing system's substantial structural and operational complexity increases, potentially leading to higher error rates for the data channel. The drawings incorporated herein and constituting part of this specification illustrate several aspects of the subject matter disclosed herein and, together with the specification, contribute to interpreting some principles relating to the disclosed embodiments. An example of an optical communication system is shown.Figure 2a shows an example of a repeater coupled to a high-loss loopback (which can be coupled to the system shown in Figure 1). Figure 2b shows an example of a repeater.Figures 3a and 3b show curve diagrams illustrating the relationship between beat frequency and time in a receiver.The present subject illustrates an exemplary optical communication system in several embodiments which can be used to determine the state of one or more portions (e.g., spans) of an optical communication path.Figure 4a shows an example of the signal flow of a data channel in an optical communication system, according to several embodiments of the current subject.The following are examples of signal flow in a DAS channel in an optical communication system shown in Figure 4a, according to several embodiments of the current subject.This section presents exemplary windowed FFT techniques in several embodiments of the current subject.This document presents exemplary processes for performing a windowed FFT by an interrogation and sensing unit and/or terminal according to several embodiments of the present subject.This presents another exemplary process for performing a windowed FFT by an interrogation and sensing unit and/or terminal according to several embodiments of the present subject.This section presents examples of FFT processes with sliding windows applied, based on several embodiments of the current subject.This section presents examples of FFT processes with sliding windows applied, based on several embodiments of the current subject.This document presents an exemplary process for performing a sliding window FFT using an interrogation and sensing unit and/or terminal according to several embodiments of the present subject.Figures 9a and 9b show various embodiments of a repeater that can be implemented in the system shown in Figure 4a according to some embodiments of the present subject.Figure 9c shows various embodiment