Multi-dimensional communication sensing system integrating optical transmission network and BOTDR / DAS distributed sensing

Abstract

The invention discloses a multidimensional communication sensing system integrating an optical transmission network and BOTDR / DAS distributed sensing, and relates to the technical field of optical fiber communication and optical fiber sensing. The system comprises an OTN transmission subsystem, an optical fiber link and a BOTDR / DAS fusion sensing subsystem. Wherein the OTN transmission subsystem is used for realizing high-capacity data transmission through an optical fiber link; and the BOTDR / DAS fusion sensing subsystem is used for realizing strain, temperature and vibration distributed measurement of an optical fiber link through a Brillouin scattering and Rayleigh backscattering mechanism. According to the system, a double-self-heterodyne demodulation architecture and a reverse wavelength division multiplexing mechanism are adopted, cooperative demodulation and high-isolation transmission of BOTDR and DAS signals are achieved under the common-fiber condition, and high-speed communication and distributed temperature, strain and vibration synchronous monitoring within the 100 km range can be achieved. According to the method, a technical foundation can be laid for realizing physical layer intelligentization of the in-service power OTN.

Description

Technical Field

[0001] This invention relates to the fields of optical fiber communication and optical fiber sensing technology, specifically to a multi-dimensional communication and sensing system that integrates an optical transmission network and BOTDR / DAS distributed sensing. Background Technology

[0002] With the rapid development of new power systems and smart grids, power communication networks are no longer limited to traditional information transmission functions, but have gradually evolved into the core nerve center supporting real-time monitoring, dynamic control, differential protection, and intelligent decision-making in the power grid. In this system, the Optical Transport Network (OTN), with its ultra-high reliability, ultra-high bandwidth, and low latency, has become a key supporting technology for the power backbone communication network. However, the physical security of OTN largely depends on the long-term stable operation of overhead composite optical cables (such as OPGW / OPPC). These cables are continuously affected by multiple coupling effects, including icing, de-icing, wind vibration, diurnal temperature variations, and extreme weather, which can easily lead to mechanical fatigue, fiber attenuation, and material aging. In severe cases, this can even result in fiber breakage, line breakage, or tower collapse, posing a direct threat to the safety and stability of the power system. Therefore, achieving real-time, accurate, and full-lifecycle monitoring of the physical state of overhead optical cables has become an urgent requirement for ensuring the resilience of power communication and the safe operation of the smart grid.

[0003] In recent years, Distributed Fiber Optic Sensing (DFOS) technology has gradually become an important means of power transmission line condition sensing due to its advantages such as long-distance coverage, fully distributed measurement, and absence of electromagnetic interference. Typical solutions include BOTDR / BOTDA systems based on Brillouin scattering, which can achieve high-precision reconstruction of fiber strain and temperature fields through the spatial distribution of Brillouin frequency shifts. Frequency shift differences between different cable segments can be used to identify splice and joint locations. External load changes or abnormal elongation manifest as fiber strain anomalies, which can be used for sag monitoring and icing load assessment. Transient high-temperature events (such as de-icing currents or lightning strikes) can cause abrupt changes in local Brillouin frequency shifts, thereby enabling real-time detection of abnormal cable temperature. Furthermore, existing research has utilized temperature phase differences to further identify icing areas, demonstrating good engineering application potential. Distributed acoustic sensing (DAS) based on Rayleigh scattering or phase-sensitive optical time-domain reflectometry (φ-OTDR) can sensitively detect micro-vibrations in optical cables, enabling estimation of galloping behavior, vibration modes, and icing thickness. Brillouin scattering and Rayleigh scattering each have their advantages and limitations in terms of the physical quantities they can sense and their spatiotemporal resolution. Brillouin scattering accurately quantifies temperature and strain, but its dynamic response is limited; Rayleigh scattering highly sensitively captures rapid vibrations, but it is difficult to provide quantitative temperature / strain information. Therefore, a single mechanism is insufficient to fully characterize the true physical state of optical cables. Only by synergistically applying these two types of distributed sensing technologies, Brillouin and Rayleigh, can we achieve full sensing of temperature, strain, and vibration across macroscopic-microscopic and multi-timescale dimensions, thereby ensuring the accuracy of optical cable anomaly diagnosis.

[0004] Meanwhile, as power communication networks evolve towards higher speeds, greater intelligence, and longer distances, optical fiber resources are becoming increasingly scarce. Despite the massive scale of optical cable deployments, fiber core resources are primarily used to carry backbone communication services, leading to a continuous compression of redundant space. Reserving independent optical fibers for sensing channels not only fails to meet service bandwidth demands but also wastes resources. In high-traffic-density backbone OTN networks, communication services occupy almost all fiber core resources, making it difficult to allocate dedicated physical channels for sensing links. Therefore, achieving co-fiber operation of communication and sensing under limited fiber conditions has gradually become a core driving force for academic attention. This has given rise to the research of Integrated Sensing and Communication in Optical Fiber (ISAC-OF), which aims to achieve real-time monitoring of temperature, strain, and vibration without sacrificing communication performance.

[0005] Extensive research has advanced ISAC-OF from various perspectives. In forward transmission-based fiber optic sensing fusion research, researchers have attempted to leverage the inherent characteristics of communication signals to achieve environmental perception. For example, they have used inductive laser interferometry or fiber polarization state analysis to detect seismic waves and water waves. Simultaneously, phase-detection-based vibration sensing systems have been used for in-service cable inspection. Vibration detection and localization are achieved using optical phase recovered from digital coherent receivers. Comparisons of phase-based and SOP-based vibration detection results show that the phase method performs better due to its higher signal-to-noise ratio and wider bandwidth. Forward transmission-based fiber optic sensing fusion systems extract optical information from the communication equipment itself to detect vibration and localize events without requiring additional dedicated detection channels or large-scale modifications to the communication link. This allows vibration detection to function as an auxiliary function of the communication network and can coexist on in-service optical fibers. However, these methods typically exhibit an end-to-end fiber integration effect, making accurate localization and separation of multi-source disturbances difficult in complex environments, resulting in significant localization errors.

[0006] Compared to forward-scattered light-based solutions, the ISAC-OF solution based on backscattered light is implemented in wavelength division multiplexing (WDM) systems. WDM enables communication networks to maintain high-speed, high-capacity data transmission while simultaneously achieving highly sensitive environmental monitoring and sensing capabilities. In 2019, Verizon / NEC and other teams reported the first field trial of vehicle monitoring on in-service, high-volume data-carrying optical fibers, demonstrating the feasibility and engineering value of simultaneously supporting high-capacity communication and environmental sensing. In subsequent, more comprehensive work (JLT 2020), the team demonstrated the simultaneous achievement of data transmission speeds up to 36.8 Tb / s and distributed fiber sensing in an operational network, and analyzed the impact of system coexistence on communication performance, showing that with reasonable wavelength / power planning, communication and sensing can coexist with low interference, enabling the monitoring of road conditions, vehicle density, and speed. Furthermore, in 2023, Yan's team proposed the ISAC-OF solution, which integrates communication and distributed vibration sensing on a single-wavelength optical fiber. This scheme utilizes an LFM optical carrier to simultaneously carry a high-speed PAM4 signal and a Φ-OTDR probe, enabling long-distance, high-precision vibration monitoring while maintaining a data transmission performance improvement of approximately 1.3 dB and an allowable transmit power improvement of approximately 7 dB.

[0007] However, the aforementioned research largely remains at the laboratory scale or in controlled scenarios, and still faces numerous challenges: First, transmission capacity and sensing accuracy are limited, making it difficult to balance high-speed communication and high-sensitivity perception; second, the methods lack adaptability to the complex and ever-changing power network environment, and stable verification under long-distance, dynamic loads is still lacking; third, existing work mostly focuses on sensing single physical quantities (such as temperature or vibration), and has not yet achieved coordinated monitoring of key parameters such as strain and vibration. This limits its application value in power system operation and maintenance, as optical cables often simultaneously endure multi-source disturbances such as thermo-mechanical coupling and wind-induced vibration during long-term operation. More importantly, current research lacks a multi-parameter sensing fusion architecture and verification framework for actual OTN deployment, and has not yet solved the problem of how to seamlessly integrate sensing functions into existing communication systems and achieve large-scale, industrial-scale implementation. In other words, current sensing fusion research cannot yet meet the urgent needs of power communication networks for full-link, real-time, and multi-dimensional monitoring. Summary of the Invention

[0008] In view of the above problems, this invention proposes a multi-dimensional communication and sensing system that integrates an optical transmission network and BOTDR / DAS distributed sensing.

[0009] The multi-dimensional communication and sensing system integrating an optical transmission network and BOTDR / DAS distributed sensing includes: an OTN transmission subsystem, an optical fiber link, and a BOTDR / DAS fusion sensing subsystem; wherein, the OTN transmission subsystem is used to achieve high-capacity data transmission through the optical fiber link; the BOTDR / DAS fusion sensing subsystem is used to achieve distributed measurement of strain, temperature, and vibration of the optical fiber link through Brillouin scattering and Rayleigh backscattering mechanisms.

[0010] The BOTDR / DAS fusion sensing subsystem includes: a laser, a first coupler, an acousto-optic modulator, a first erbium-doped fiber amplifier, a first circulator, a second erbium-doped fiber amplifier, a second circulator, a fiber optic grating filter, a dense wavelength division multiplexer, a third coupler, a first balanced detector, a second coupler, an electro-optic modulator, an orthogonal polarization switch, a fourth coupler, a second balanced photodetector, a bandpass filter, an envelope detector, a data acquisition card, a pulse generator, and a microwave signal source.

[0011] The laser's output is connected to the input of a first coupler, and the output of the first coupler is connected to the inputs of an acousto-optic modulator and a second coupler. The output of the acousto-optic modulator is connected to the input of a first erbium-doped fiber amplifier, and the output of the first erbium-doped fiber amplifier is connected to the first port of a first circulator. The second port of the first circulator is connected to the optical demultiplexer of the OTN transmission subsystem. The third port of the first circulator is connected to the input of a second erbium-doped fiber amplifier, and the output of the second erbium-doped fiber amplifier is connected to the first port of the second circulator. The second port of the second circulator is connected to the input of a fiber Bragg grating filter, and the output of the fiber Bragg grating filter is connected to the input of a dense wavelength division multiplexer (DWDM). The output of the DWDM is connected to the input of a third coupler, and the output of the third coupler is connected to a first balanced detector.

[0012] The output of the second coupler is connected to the input of the third coupler and the electro-optic modulator, respectively. The output of the electro-optic modulator is connected to the input of the quadrature polarization switch. The third port of the second circulator and the output of the quadrature polarization switch are connected to the input of the fourth coupler, respectively. The output of the fourth coupler is connected to the input of the second balanced photodetector. The output of the second balanced photodetector is connected to the input of the bandpass filter. The output of the bandpass filter is connected to the input of the envelope detector.

[0013] The outputs of the first balanced detector and the envelope detector are connected to the data acquisition card, respectively; the output of the pulse generator is connected to the input of the acousto-optic modulator; and the output of the microwave signal source is connected to the input of the electro-optic modulator.

[0014] Furthermore, the OTN transmission subsystem includes a transmitter, a transmitter optical channel transmission unit, an optical multiplexer, an optical amplifier, an optical demultiplexer, a receiver optical channel transmission unit, and a receiver; wherein, the transmitter is connected to the input of the transmitter optical channel transmission unit, the output of the transmitter optical channel transmission unit is connected to the input of the optical multiplexer, the output of the optical multiplexer is connected to the input of the optical amplifier, the output of the optical amplifier is connected to the input of the optical demultiplexer, the output of the optical demultiplexer is connected to the input of the receiver optical channel transmission unit, and the output of the receiver optical channel transmission unit is connected to the receiver.

[0015] Furthermore, the working process of the BOTDR / DAS fusion sensing subsystem includes: the laser output light is split into upper branch light and lower branch light by a first coupler; the upper branch light is modulated into pump pulse light by an acousto-optic modulator, and a frequency shift is introduced; the acousto-optic modulator is driven by a pulse generator; the pump pulse light output by the acousto-optic modulator is amplified by a first erbium-doped fiber amplifier and injected into the first port of the first circulator, and coupled to the DWDM channel of the optical demultiplexer of the OTN transmission subsystem through the second port of the first circulator; the backscattered signal light returned by the fiber link is led out through the third port of the first circulator and enters the second erbium-doped fiber amplifier for echo amplification, and then injected into the fiber grating filter through the second circulator; the transmitted light output by the fiber grating filter includes Rayleigh scattering signal light and Brillouin-Stokes light, and the reflected light is Brillouin-anti-Stokes light; the transmitted light is filtered out by a dense wavelength division multiplexer to remove the backscattered Rayleigh light;

[0016] The lower branch light is split into two paths by the second coupler. One path serves as the reference light for Rayleigh scattering and is mixed with the backscattered Rayleigh light filtered by the dense wavelength division multiplexer via the third coupler. This mixture is then detected by the first balanced detector, and its beat frequency signals I and Q are recorded by the data acquisition card. The other path of the lower branch light serves as the reference light for Brillouin scattering and is frequency modulated by an electro-optic modulator driven by a microwave signal source. The frequency-modulated light output from the electro-optic modulator is polarized by an orthogonal polarization switch. The reflected light output from the fiber optic grating filter is mixed with the frequency-modulated reference light after polarization switching in the fourth coupler. The fixed frequency component of its heterodyne Brillouin signal is received by the second balanced photodetector, filtered by a bandpass filter, and extracted by an envelope detector. Finally, it is recorded by the data acquisition card.

[0017] Furthermore, the laser is a narrow linewidth laser with a linewidth of 3 kHz and a center wavelength of 1549.972 nm; the fiber grating filter has a bandwidth of 0.08 nm and a center wavelength of 1550.06 nm; and the dense wavelength division multiplexer has a center wavelength of 1549.972 nm.

[0018] Furthermore, the splitting ratios of the first coupler, the third coupler, and the fourth coupler are all 50:50; the splitting ratio of the second coupler is 20:80.

[0019] Furthermore, the microwave signal emitted by the microwave signal source sweeps the frequency in the range of 11.12-11.22 GHz with a step of 4 MHz; the center frequency of the bandpass filter is 300 MHz and the bandwidth is 100 MHz.

[0020] Furthermore, the OTN transmission subsystem adopts an OTN configuration with a single-channel rate of 100 Gbit / s, based on the polarization multiplexing QPSK coherent reception modulation format, and operates in the C-band; it adopts an 88-wavelength DWDM scheme with a channel spacing of 50 GHz, and each wavelength channel independently carries different data services.

[0021] Furthermore, the upper branch light serves as the probe pulse light, and the lower branch light serves as the local oscillator light for the BOTDR and DAS, respectively; the probe pulse light is represented as:

[0022] ;

[0023] In the formula, Indicates the amplitude of the probe pulse light; Indicates the frequency of the laser; The frequency shift introduced by the acousto-optic modulator is represented by t; time is represented by t. Indicates the initial phase of the probe pulse;

[0024] The local oscillator light of the BOTDR and DAS are respectively represented as: and :

[0025] ;

[0026] ;

[0027] In the formula, and These represent the amplitudes of the Brillouin and Rayleigh oscillators, respectively. , These represent the initial phases of the Brillouin and Rayleigh oscillators, respectively.

[0028] The total optical field of the backscattered signal light returned by fiber link 2 is expressed as:

[0029] ;

[0030] In the formula, , and These are Rayleigh scattering, Brillouin-Stokes scattering, and Brillouin anti-Stokes scattering, respectively, where:

[0031] ;

[0032] ;

[0033] ;

[0034] in , and These represent the amplitudes of Rayleigh scattering, Brillouin scattering Stokes ray, and Brillouin scattering anti-Stokes ray, respectively. Indicates Brillouin frequency shift; , , These are the phase differences between Rayleigh scattering, Brillouin scattering Stokes ray, Brillouin scattering anti-Stokes ray, and their respective local oscillator rays; , , These are the initial phases of Rayleigh scattering, Brillouin-Stokes scattering, and Brillouin-anti-Stokes scattering, respectively.

[0035] Furthermore, the optical signal output by the first balanced detector is represented as:

[0036] ;

[0037] The optical signal output by the second balanced photodetector is represented as follows:

[0038] ;

[0039] In the formula, and These represent the power of Rayleigh scattering and spontaneous Purlyan scattering, respectively. Indicates proportional to; and These represent the power of the Brillouin oscillator and the Rayleigh oscillator, respectively.

[0040] The beneficial technical effects of this invention are:

[0041] This invention proposes a multi-dimensional communication and sensing system integrating an optical transmission network and BOTDR / DAS distributed sensing. It is a communication-sensing integrated system for power optical transmission networks (OTN), achieving high-speed communication and distributed synchronous monitoring of temperature, strain, and vibration over a range of 100 km. The system employs a dual self-heterodyne demodulation architecture and an inverse wavelength division multiplexing mechanism to achieve coordinated demodulation and high-isolation transmission of BOTDR and DAS signals under shared-fiber conditions. Experimental results show that while transmitting 100 Gb / s PDM-QPSK signals, the system's OSNR remains stable above 23 dB, and the bit error rate (BER) is below 10⁻⁻⁶. 7 The system exhibits no significant interference; the BOTDR subsystem achieves a spatial resolution of 40 m and a frequency shift accuracy of 2 MHz, while the DAS subsystem has a phase noise of 0.37 rad over a range of 100 km, accurately detecting low-frequency vibrations of 1 Hz. This invention verifies the co-fiber compatibility of communication and distributed sensing, laying a technical foundation for the realization of physical layer intelligence in in-service power OTN systems. Attached Figure Description

[0042] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings. Several embodiments of the invention are illustrated in the drawings by way of example and not limitation, wherein:

[0043] Figure 1 This is the overall architecture diagram of the multi-dimensional communication and sensing system integrating optical transmission network and BOTDR / DAS distributed sensing described in this invention;

[0044] Figure 2 This is an example of the sensing distance measurement results of the BOTDR subsystem in an embodiment of the present invention;

[0045] Figure 3 This is an example of the spatial resolution measurement results at 75km using the BOTDR subsystem in this embodiment of the invention;

[0046] Figure 4 This is an example of the spatial resolution measurement results of the BOTDR subsystem at 50km in an embodiment of the present invention;

[0047] Figure 5 This is an example of the accuracy measurement results of the BOTDR subsystem in an embodiment of the present invention;

[0048] Figure 6 This is an example of the sensing distance measurement results of the DAS subsystem in an embodiment of the present invention;

[0049] Figure 7 This is an example of the vibration phase measurement results at 75km on the piezoelectric ceramic tube of the DAS subsystem in this embodiment of the invention;

[0050] Figure 8 This is an example of the vibration frequency measurement results at 75km on the piezoelectric ceramic tube of the DAS subsystem in this embodiment of the invention;

[0051] Figure 9 This is an example of the phase spatiotemporal distribution diagram at 75km on the piezoelectric ceramic tube of the DAS subsystem in this embodiment of the invention;

[0052] Figure 10 This is an example of the phase linearity measurement results of the DAS subsystem in an embodiment of the present invention. Detailed Implementation

[0053] The principles and spirit of the invention will now be described with reference to several exemplary embodiments. It should be understood that these embodiments are given merely to enable those skilled in the art to better understand and implement the invention, and are not intended to limit the scope of the invention in any way. Rather, these embodiments are provided to make this disclosure more thorough and complete, and to fully convey the scope of this disclosure to those skilled in the art.

[0054] This invention proposes a long-distance communication-sensing fusion system for power OTN, achieving integrated communication-sensing coverage of approximately 100km under single-end conditions. This system can be seamlessly integrated into existing OTN networks, enabling parallel operation of high-speed communication and distributed temperature / strain / vibration sensing. This ensures transmission performance while enhancing the power OTN network's ability to perceive and protect against external threats (such as icing galloping and mechanical impacts). It also lays the foundation for building a smart power communication network with self-sensing, self-diagnostic, and self-recovery capabilities. Its ultimate goal is to evolve power optical cables from a single communication carrier into an integrated communication-sensing infrastructure, providing crucial support for the future energy internet and ubiquitous power internet of things.

[0055] Figure 1 This invention demonstrates the overall architecture of a multi-dimensional communication and sensing system integrating an optical transmission network (OTN) and distributed optical fiber sensing (DOFS). This system organically combines an OTN with DOFS to achieve synchronous high-capacity data transmission and distributed environmental sensing along the same optical fiber link. It consists of three core components: an OTN transmission subsystem 1, an optical fiber link 2, and a BOTDR / DAS fusion sensing subsystem 3. The OTN transmission subsystem 1 enables ultra-high-speed, high-capacity data transmission via the optical fiber link 2, while the BOTDR / DAS fusion sensing subsystem 3 achieves distributed measurement of strain, temperature, and vibration via the optical fiber link 2 through Brillouin scattering and Rayleigh backscattering mechanisms.

[0056] The OTN transmission subsystem 1 includes a transmitter 11, a transmitter optical channel transmission unit 12, an optical multiplexer 13, an optical amplifier 14, an optical demultiplexer 15, a receiver optical channel transmission unit 16, and a receiver 17. The transmitter 11 is connected to the input of the transmitter optical channel transmission unit 12, the output of the transmitter optical channel transmission unit 12 is connected to the input of the optical multiplexer 13, the output of the optical multiplexer 13 is connected to the input of the optical amplifier 14, the output of the optical amplifier 14 is connected to the input of the optical demultiplexer 15, the output of the optical demultiplexer 15 is connected to the input of the receiver optical channel transmission unit 16, and the output of the receiver optical channel transmission unit 16 is connected to the receiver 17.

[0057] The BOTDR / DAS fusion sensing subsystem 3 includes: a laser 31, a first coupler 32, an acousto-optic modulator 33, a first erbium-doped fiber amplifier 34, a first circulator 35, a second erbium-doped fiber amplifier 36, a second circulator 37, a fiber optic grating filter 38, a dense wavelength division multiplexer 39, a third coupler 310, a first balanced detector 311, a second coupler 312, an electro-optic modulator 313, an orthogonal polarization switch 314, a fourth coupler 315, a second balanced photodetector 316, a bandpass filter 317, an envelope detector 318, a data acquisition card 319, a pulse generator 320, and a microwave signal source 321.

[0058] The laser 31 is connected to the input of the first coupler 32, and the output of the first coupler 32 is connected to the input of the acousto-optic modulator 33 and the second coupler 312. The output of the acousto-optic modulator 33 is connected to the input of the first erbium-doped fiber amplifier 34, and the output of the first erbium-doped fiber amplifier 34 is connected to the first port 35-1 of the first circulator 35. The second port 35-2 of the first circulator 35 is connected to the optical demultiplexer 15 of the OTN transmission subsystem 1. The third port 35-3 of the first circulator 35 is connected to the input of the second erbium-doped fiber amplifier 36, and the output of the second erbium-doped fiber amplifier 36 is connected to the first port 37-1 of the second circulator 37. The second port 37-2 of the second circulator 37 is connected to the input of the fiber optic grating filter 38, and the output of the fiber optic grating filter 38 is connected to the input of the dense wavelength division multiplexer 39. The output of the dense wavelength division multiplexer 39 is connected to the input of the third coupler 310, and the output of the third coupler 310 is connected to the first balanced detector 311.

[0059] The output of the second coupler 312 is connected to the input of the third coupler 310 and the electro-optic modulator 313, respectively. The output of the electro-optic modulator 313 is connected to the input of the quadrature polarization switch 314. The third port 37-3 of the second circulator 37 and the output of the quadrature polarization switch 314 are connected to the input of the fourth coupler 315, respectively. The output of the fourth coupler 315 is connected to the input of the second balanced photodetector 316. The output of the second balanced photodetector 316 is connected to the input of the bandpass filter 317. The output of the bandpass filter 317 is connected to the input of the envelope detector 318.

[0060] The outputs of the first balanced detector 311 and the envelope detector 318 are respectively connected to the data acquisition card 319; the output of the pulse generator 320 is connected to the input of the acousto-optic modulator 33; and the output of the microwave signal source 321 is connected to the input of the electro-optic modulator 313.

[0061] According to an embodiment of the present invention, in the communication section, the subsystem adopts an OTN configuration with a single-channel rate of 100 Gbit / s, based on the polarization multiplexing (D)QPSK coherent receive modulation format, and operates in the C-band; the transmission subsystem adopts an 88-wavelength DWDM scheme with a channel spacing of 50 GHz, and each wavelength channel independently carries different data services. The OTN network architecture uses the Alcatel-Lucent 1830 optical service switch (PSS-32), which is designed for multi-layer packet optical transmission scenarios from regional to long-haul, providing ultra-large-scale transmission capabilities. Each node is equipped with an S2AD200H type 100G tributary integration board, integrating client and line-side functions on a single module to reduce equipment space and power consumption. To ensure stable multiplexing and demultiplexing of DWDM signals, the subsystem uses SFD44 (even-wavelength) / SFD44B (odd-wavelength) wavelength multiplexers / demultiplexers to maintain a precise 50 GHz channel spacing between adjacent optical carriers. Figure 1 The reference points for the optical link are defined as follows: MPI-S represents the reference point after the OMU and at the OA output interface, with a transmit optical power of 0.97 dBm; MPI-R represents the reference point before the ODU and at the OA input interface, with a receive optical power of -23.96 dBm and a cross-segment loss of 24.93 dB; Rn represents the reference point after the ODU and before the OTU input interface, with the receive optical power monitored by the network management system ranging from -8.01 to -8.00 dBm over a long period.

[0062] The BOTDR / DAS fusion sensing subsystem 3 uses a narrow linewidth laser 31 as the light source, with a linewidth of 3kHz and a center wavelength of 1549.972nm (193.4180THz); the laser output is split into two paths by a 50:50 optical coupler (first coupler 32).

[0063] In the upper branch, the light is modulated by an acousto-optic modulator (AOM) 33 into a pump pulse with a pulse width of 400 ns (corresponding to a spatial resolution of 40 m), and a frequency shift of 300 MHz is introduced. The AOM is driven by a pulse generator 320. The output pump pulse is amplified by the first erbium-doped fiber amplifier (EDFA1) 34 and injected into the first port 35-1 of the first circulator 35. It is then coupled to the DWDM channel corresponding to the optical demultiplexer 15 of the OTN transmission subsystem 1 through the second port 35-2. The backscattered signal in the sensing fiber (i.e., the backscattered signal light returned by the fiber link 2) is extracted through the third port 35-3 and enters the second erbium-doped fiber amplifier (EDFA2) 36 for echo amplification. It is then injected into the fiber grating filter (FBG) 38 through the second circulator 37. The FBG has a bandwidth of 0.08nm and a center wavelength of 1550.06nm. Its transmitted light includes Rayleigh scattering signal and Brillouin-Stokes light, and the reflected light is Brillouin-anti-Stokes light. The transmitted light is filtered out by the dense wavelength division multiplexer (DWDM) 39 to remove Rayleigh scattering light. The center wavelength of the DWDM is 1549.972nm.

[0064] The light from the lower branch is split into two paths by a 50:50 coupler (second coupler 312). One path serves as the Rayleigh scattering reference light, which is mixed with the back Rayleigh scattering (RBS) light filtered out by the dense wavelength division multiplexer (DWDM) 39 via a 2×2 optical coupler (third coupler 310), resulting in a 300-bandwidth optical path. The first balanced detector (BPD1) 311 detects the frequency of the Brillouin light at MHz, and its beat frequency signal I and Q paths are recorded by a data acquisition card (DAQ). The other path of the lower branch light serves as the reference light for Brillouin scattering. The Brillouin reference light is frequency modulated by an electro-optic modulator (EOM) 313, which is driven by a microwave signal source (MG) 321. The microwave signal sweeps in the range of 11.12-11.22 GHz in 4 MHz steps and is polarized by an orthogonal polarization switch (PS) 314. The Brillouin anti-Stokes light and the frequency-modulated reference light are mixed in a 2×2 optical coupler (fourth coupler 315). The fixed frequency component of its heterodyne Brillouin signal is received by a second balanced photodetector (BPD2) 316 with a bandwidth of 350 MHz, and extracted by a bandpass filter (center frequency 300 MHz, bandwidth 100 MHz) 317 and an envelope detector (ED) 318. Finally, the signal is analyzed by a sampling rate of 50 MHz. The MHz data acquisition card (DAQ) records data for subsequent processing.

[0065] The technical principles of Brillouin and Rayleigh sensing during the operation of the BOTDR / DAS fusion sensing subsystem 3 are as follows.

[0066] The BOTDR and DAS signals are demodulated using a dual self-heterodyne probe method. The continuous light generated by the narrow-linewidth laser 31 is split into two parts: one part serves as the probe pulse, and the other part is split into two parts, serving as the local oscillator light for the BOTDR and DAS, respectively. In common DAS systems, the acousto-optic modulator 33 modulates the probe light into an optical pulse and introduces a frequency shift. (Here, 300MHz) is used for heterodyne detection. The probe light and local oscillator light signals can be represented as follows:

[0067] (1)

[0068] (2)

[0069] (3)

[0070] in , and The amplitudes of the probe pulse light, Brillouin local oscillator light, and Rayleigh local oscillator light are respectively used. It is the frequency of the laser. It is the frequency shift introduced by the acousto-optic modulator. , , These are the initial phases of the pulsed light, the Brillouin local oscillator, and the Rayleigh local oscillator, respectively.

[0071] The total backscattered light field is a combination of Rayleigh (RBS), Brillouin-Stokes (SpBS), and anti-Brillouin-Stokes (ASBS) components. The total light field of the scattered light is:

[0072] (4)

[0073] in , and These are Rayleigh scattering, Brillouin-Stokes scattering, and Brillouin anti-Stokes scattering, respectively.

[0074] (5)

[0075] (6)

[0076] (7)

[0077] in , and These represent the amplitudes of Rayleigh scattering, Brillouin scattering Stokes ray, and Brillouin scattering anti-Stokes ray, respectively. It is the Brillouin frequency shift. , , These represent the phase changes of Rayleigh scattering, Brillouin scattering Stokes ray, and Brillouin scattering anti-Stokes ray, respectively. , , These are the initial phases of Rayleigh scattering, Brillouin-Stokes scattering, and Brillouin-anti-Stokes scattering, respectively.

[0078] Rayleigh scattering and Brillouin scattering light are filtered and then mixed with their corresponding local oscillator light at a 3dB coupler. The beat frequency signal AC output components of the detector (i.e., the optical signal output by the first balanced detector 311 and the optical signal output by the second balanced photodetector 316) are expressed as follows:

[0079] (8)

[0080] (9)

[0081] in, Indicates proportional to; and Let represent the power of Rayleigh scattering and spontaneous Pleistocene scattering, respectively. , , These represent the phase differences between the local reference light and the Rayleigh scattered light, and between the Stokes light and the anti-Stokes light, respectively.

[0082] The data acquired by the data acquisition card 319 is input into a computer for signal fusion and feature decoupling. Using signal feature extraction, filtering, modal analysis, and multi-parameter joint determination methods, the influence of different physical quantities is separated, improving measurement accuracy and reducing the false alarm rate. As an example, the specific process may include: denoising and normalizing the fiber optic sensing signal acquired by the data acquisition card 319; extracting the temperature, strain, vibration, and attenuation characteristics corresponding to the fiber optic sensing signal; and comprehensively determining the strain, temperature, and vibration states of each part of the fiber optic link 2 based on the temperature, strain, vibration, and attenuation characteristics. The above signal fusion and feature decoupling process is existing technology and will not be elaborated upon in this embodiment.

[0083] The system proposed in this invention provides a core physical architecture for integrated communication and sensing based on a reverse wavelength division multiplexing (WDM) mechanism. Through precise signal waveform planning and transmission mechanism modeling, it achieves minimal interference and high isolation co-fiber transmission of sensing signals to communication services while ensuring ultra-large communication capacity. In this physical architecture, OTN communication signals and BOTDR / DAS sensing signals share the same optical fiber but are transmitted in opposite directions. The communication subsystem adopts a forward transmission mode, with multiple DWDM service channels transmitted from the core node to the remote user, achieving high-bandwidth information transmission. Meanwhile, the sensing subsystem uses single-wavelength pulsed light to propagate along the reverse path (i.e., from the user end to the core node) to acquire scattering information from the optical fiber along the way. Because the pulse signal of the DFOS system has a high peak power, if it propagates in the same direction as the data channel, it will interfere with the communication signal due to the nonlinear effect of the optical fiber. This reverse transmission and wavelength division multiplexing cooperative mechanism makes the effective interaction time and interaction length between the communication signal and the sensing signal extremely short, which greatly reduces the interference caused by optical fiber nonlinearity, effectively suppresses the crosstalk between the communication and sensing signals, and builds the physical basis for low interference and high fidelity co-fiber transmission, providing key support for realizing the network architecture of "deep integration of communication and sensing".

[0084] Further experiments were conducted to evaluate the transmission and sensing performance of the system proposed in this invention.

[0085] 1) Transmission Performance Evaluation: In the sensing fusion experiment, the fiber optic link consisted of four fused fiber optic rolls, each approximately 25.25 km long, for a total length of approximately 101 km. The collaborative performance of the communication and distributed fiber optic sensing systems was tested using the system proposed in this invention. While the sensing system maintained continuous measurement throughout the process, the communication channel transmitted a 100 Gbit / s Ethernet (100GE) signal based on polarization-multiplexed quadrature phase modulation (PDM QPSK). At a center wavelength of 193.35 THz, this signal was continuously transmitted for 15 minutes without any detected bit errors or packet loss, verifying the high reliability and stability of the system at this wavelength and rate.

[0086] At point Rn, the optical signal-to-noise ratio (OSNR) is measured using a spectral analyzer. The verification path wavelength is displayed in the center of the screen. The cursor is positioned at the peak power of this wavelength, with the integration bandwidth being the current path interval. The optical power value at this wavelength is recorded as P1 (mW) according to the instrument's readings. The signal source is then turned off, and the background noise power P2 (mW) is recorded at the same bandwidth. With the integration bandwidth set to 0.1 nm, the optical path value is recorded as PA (mW). Therefore, the formula for calculating the channel's OSNR (dB) is:

[0087] (10)

[0088] The measured OSNR at Rn point was 23.28~23.73 dB, indicating that the system has excellent optical transmission quality and the sensing did not affect the communication.

[0089] During long-term joint operation testing of the sensor system, the bit error rate before error correction at point Rn was continuously monitored, and its value remained stable at 8.71 × 10⁻⁶. -8 ~8.89×10 -8 The values ​​were between [values] and [values], far below the FEC error correction threshold, verifying that the system can still maintain stable and error-free communication performance under distributed sensing parallel operation.

[0090] 2) Sensing Performance Evaluation: In the BOTDR subsystem experiment of the fusion system, a pump pulse with a pulse width of 400 ns was used, corresponding to a spatial resolution of approximately 40 m. The peak power of the pump pulse was set to 300 mW, and the double-sideband detection power of the local reference light was 400 μW. The signal was acquired through 10,000 averaging processes, and a single complete test took approximately 15 minutes. The fiber under test was composed of four fused fiber rolls, each approximately 25.25 km long, for a total length of approximately 101 km.

[0091] Measurement results show that the total length of the fiber optic link under test is 100.977 km. Figure 2 As shown, the Brillouin frequency shift distribution can be clearly divided into four segments, each approximately 25.25 km long. The first three segments are made of G.654E fiber, with Brillouin frequency shifts greater than 11 GHz; the last segment is made of G.652D fiber, with a Brillouin frequency shift of approximately 10.85 GHz. A Brillouin frequency shift transition region appears at the fiber splice at 75.67 km, which can be used to verify the spatial resolution of the system.

[0092] To verify the spatial resolution of the BOTDR subsystem, a 25.25 km length of G.652D fiber was fused to the G.654E fiber at a distance of 75.67 km. Because the Brillouin shift of the G.652D fiber (approximately 10.85 GHz) is significantly lower than that of the preceding G.654E fiber (greater than 11 GHz), a distinct Brillouin shift transition region was formed at the splice point. This was used to simulate abrupt changes in Brillouin shift caused by temperature or strain, such as... Figure 3 As shown. However, the large difference in Brillouin frequency shift between the two optical fibers causes the transition region to exhibit an abrupt change, meaning a jump occurs only at one location, making it unsuitable for precise spatial resolution calibration. Therefore, a calibration point of 50.46 km was selected. At this location, the Brillouin frequency shift at the splice of the two fiber segments gradually changes from 11.01 GHz to 11.017 GHz, with an overall difference of approximately 7 MHz. Figure 4As shown. Defining the spatial resolution by the length of the Brillouin frequency shift transition region from 10% (50.439 km) to 90% (50.479 km), the spatial resolution of the BOTDR subsystem is 40 m.

[0093] Under the condition of keeping the temperature and strain of the fiber under test constant, 30 sets of Brillouin frequency shift data were repeatedly collected, and the standard deviation of each measurement point was calculated to characterize the measurement accuracy of the BOTDR subsystem under zero external disturbance. The measurement results are as follows: Figure 5 As shown, the overall measurement accuracy of the entire fiber under test is better than 2MHz. However, a significant anomaly appears at 75.67km, corresponding to the fusion splice between G.654E and G.652D fibers. Due to the difference in Brillouin frequency shift between the two fibers, the transition region formed at the splice causes distortion of the Brillouin gain spectrum, thus degrading the measurement accuracy in this region.

[0094] Further analysis revealed that within the 0–90 km range, the system's measurement accuracy remained below 1 MHz; however, in the 90–100 km range, with only a 10 km increase in sensing distance, the measurement accuracy decreased from approximately 1 MHz to nearly 2 MHz. This phenomenon indicates a significantly accelerated rate of measurement accuracy degradation at the fiber optic tail end, becoming a limiting factor for further increases in the sensing distance of the BOTDR subsystem.

[0095] The DAS subsystem can acquire vibration information of optical fibers and can be used for icing monitoring of OPGW optical cables. Considering that the vibration of optical cables under icing conditions is mainly concentrated in the low-frequency range of about 1Hz, this invention selects a 1Hz vibration source as the driving signal in the vibration test of the fusion system to verify the system's monitoring performance of low-frequency vibration signals.

[0096] After the optical pulse generated by the fusion system enters the optical fiber, the DAS subsystem demodulates the phase of the Rayleigh scattered light, and its optical pulse configuration parameters are consistent with those of the BOTDR subsystem. The DAS subsystem acquires a phase time-domain data point and calculates the phase sensing distance accordingly. Figure 6As shown in the figure, the phase noise gradually increases with the increase of sensing distance, with a maximum phase noise of 0.37 rad. The total length of the fiber under test is 100.982 km. A 12 m long fiber was spliced ​​at the connection point of two fiber segments at 75.74 km and wound around a piezoelectric ceramic tube. By applying a 3 Vpp, 1 Hz sinusoidal driving signal, the fiber wound on the PZT was made to vibrate periodically. As can be seen from the figure, a significant phase change occurs from 75.72 km to 75.77 km, with a maximum phase amplitude of 1.43 rad. Since the optical pulse width can be used to characterize the spatial resolution of the DAS subsystem, and the spatial resolution of the BOTDR subsystem has been verified and its optical pulse width is the same as that of the DAS subsystem, the spatial resolution of the DAS subsystem is not tested separately.

[0097] The DAS subsystem samples at a frequency of 500Hz, continuously acquiring vibration data for 20 seconds. The phase signal from the vibration region at 75.74km is selected, such as... Figure 7 As shown in the figure, the demodulated phase signal contains 20 complete sine cycles, and the waveform is consistent with the applied driving signal, with a phase change of approximately 5 rad per cycle. Fast Fourier Transform (FFT) analysis was performed on the phase signal of this vibration region, and the results are as follows. Figure 8 As shown in the figure, the peak frequency corresponds to 1Hz, which is exactly the same as the driving signal frequency, and the signal-to-noise ratio (SNR) is 12.1dB, indicating that the DAS subsystem can accurately demodulate the frequency characteristics of the low-frequency vibration signal. Figure 9 The spatiotemporal distribution of fiber phase within a 20s time range and a spatial range of 70km to 80km was demonstrated. A significant periodic phase change was clearly observed at 75.74km, which coincides with the installation point of the PZT and the vibration frequency of its driving signal, further verifying the low-frequency vibration detection capability of the DAS subsystem.

[0098] To verify the phase demodulation accuracy and linear response characteristics of the DAS subsystem, the voltage amplitude driving the PZT was adjusted in 0.5Vpp increments, increasing from 1Vpp to 5Vpp, and the corresponding phase signal data were acquired sequentially. For example... Figure 10 As shown, under different driving voltages, the demodulated phase signals all exhibit typical sinusoidal waveforms, and their amplitude gradually increases with the increase of the driving voltage. For the phase signal under each voltage condition, the difference between the maximum and minimum phase values ​​within one period is calculated, and the obtained peak-to-peak phase values ​​are linearly fitted to the driving voltage. The results show that the phase change of the DAS subsystem under different voltage excitations has a good linear relationship with the driving voltage, indicating that the subsystem has high phase demodulation accuracy and linear response performance.

[0099] While the spirit and principles of the invention have been described with reference to several specific embodiments, it should be understood that the invention is not limited to the disclosed specific embodiments, and the division of aspects does not imply that features in these aspects cannot be combined for benefit; such division is merely for ease of description. The invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A multi-dimensional communication and sensing system integrating optical transmission network and BOTDR / DAS distributed sensing, characterized in that, include: The system comprises an OTN transmission subsystem (1), an optical fiber link (2), and a BOTDR / DAS fusion sensing subsystem (3); wherein the OTN transmission subsystem (1) is used to achieve high-capacity data transmission through the optical fiber link (2); and the BOTDR / DAS fusion sensing subsystem (3) is used to achieve distributed measurement of strain, temperature, and vibration of the optical fiber link (2) through Brillouin scattering and Rayleigh backscattering mechanisms. The BOTDR / DAS fusion sensing subsystem (3) includes: a laser (31), a first coupler (32), an acousto-optic modulator (33), a first erbium-doped fiber amplifier (34), a first circulator (35), a second erbium-doped fiber amplifier (36), a second circulator (37), a fiber optic grating filter (38), a dense wavelength division multiplexer (39), a third coupler (310), a first balanced detector (311), a second coupler (312), an electro-optic modulator (313), an orthogonal polarization switch (314), a fourth coupler (315), a second balanced photodetector (316), a bandpass filter (317), an envelope detector (318), a data acquisition card (319), a pulse generator (320), and a microwave signal source (321). The output of the laser (31) is connected to the input of the first coupler (32), and the output of the first coupler (32) is connected to the inputs of the acousto-optic modulator (33) and the second coupler (312). The output of the acousto-optic modulator (33) is connected to the input of the first erbium-doped fiber amplifier (34), and the output of the first erbium-doped fiber amplifier (34) is connected to the first port (35-1) of the first circulator (35). The second port (35-2) of the first circulator (35) is connected to the optical demultiplexer (15) of the OTN transmission subsystem (1). The three-port (35-3) is connected to the input of the second erbium-doped fiber amplifier (36). The output of the second erbium-doped fiber amplifier (36) is connected to the first port (37-1) of the second circulator (37). The second port (37-2) of the second circulator (37) is connected to the input of the fiber grating filter (38). The output of the fiber grating filter (38) is connected to the input of the dense wavelength division multiplexer (39). The output of the dense wavelength division multiplexer (39) is connected to the input of the third coupler (310). The output of the third coupler (310) is connected to the first balanced detector (311). The output of the second coupler (312) is connected to the input of the third coupler (310) and the electro-optic modulator (313), respectively. The output of the electro-optic modulator (313) is connected to the input of the quadrature polarization switch (314). The third port (37-3) of the second circulator (37) and the output of the quadrature polarization switch (314) are connected to the input of the fourth coupler (315), respectively. The output of the fourth coupler (315) is connected to the input of the second balanced photodetector (316). The output of the second balanced photodetector (316) is connected to the input of the bandpass filter (317). The output of the bandpass filter (317) is connected to the input of the envelope detector (318). The outputs of the first balanced detector (311) and the envelope detector (318) are respectively connected to the data acquisition card (319); the output of the pulse generator (320) is connected to the input of the acousto-optic modulator (33); and the output of the microwave signal source (321) is connected to the input of the electro-optic modulator (313).

2. The multi-dimensional communication and sensing system integrating optical transmission network and BOTDR / DAS distributed sensing according to claim 1, characterized in that, The OTN transmission subsystem (1) includes a transmitter (11), a transmitter optical channel transmission unit (12), an optical multiplexer (13), an optical amplifier (14), an optical demultiplexer (15), a receiver optical channel transmission unit (16), and a receiver (17). The transmitter (11) is connected to the input of the transmitter optical channel transmission unit (12), the output of the transmitter optical channel transmission unit (12) is connected to the input of the optical multiplexer (13), the output of the optical multiplexer (13) is connected to the input of the optical amplifier (14), the output of the optical amplifier (14) is connected to the input of the optical demultiplexer (15), the output of the optical demultiplexer (15) is connected to the input of the receiver optical channel transmission unit (16), and the output of the receiver optical channel transmission unit (16) is connected to the receiver (17).

3. The multi-dimensional communication and sensing system integrating an optical transmission network and BOTDR / DAS distributed sensing according to claim 1 or 2, characterized in that, The working process of the BOTDR / DAS fusion sensing subsystem (3) includes: the light output from the laser (31) is split into an upper branch light and a lower branch light by the first coupler (32); the upper branch light is modulated into a pump pulse light by the acousto-optic modulator (33) and a frequency shift is introduced; the acousto-optic modulator (33) is driven by the pulse generator (320); the pump pulse light output from the acousto-optic modulator (33) is amplified by the first erbium-doped fiber amplifier (34) and injected into the first port (35-1) of the first circulator (35), and coupled through the second port (35-2) of the first circulator (35). The backscattered signal light returned from the optical demultiplexer (15) of the OTN transmission subsystem (1) is led out through the third port (35-3) of the first circulator (35) and enters the second erbium-doped fiber amplifier (36) for echo amplification. Then it is injected into the fiber grating filter (38) through the second circulator (37). The transmitted light output by the fiber grating filter (38) includes Rayleigh scattering signal light and Brillouin-Stokes light, and the reflected light is Brillouin-Stokes light. The transmitted light is filtered out by the dense wavelength division multiplexer (39) to remove the backscattered Rayleigh light. The lower branch light is split into two paths by the second coupler (312). One path serves as the reference light for Rayleigh scattering and is mixed with the backscattered Rayleigh light filtered out by the dense wavelength division multiplexer (39) through the third coupler (310). It is then detected by the first balanced detector (311), and its beat frequency signals I and Q are recorded by the data acquisition card (319). The other path of the lower branch light serves as the reference light for Brillouin scattering and is frequency modulated by the electro-optic modulator (313). The electro-optic modulator (313) is powered by a microwave signal source. (321) Drive; The frequency-modulated light output by the electro-optic modulator (313) is switched in polarization state by the orthogonal polarization switch (314); The reflected light output by the fiber grating filter (38) and the frequency-modulated reference light after switching polarization state are mixed in the fourth coupler (315), and the fixed frequency component of its heterodyne Brillouin signal is received by the second balanced photodetector (316), filtered by the bandpass filter (317) and detected and extracted by the envelope detector (318), and finally recorded by the data acquisition card (319).

4. The multi-dimensional communication and sensing system integrating an optical transmission network and BOTDR / DAS distributed sensing according to claim 1 or 2, characterized in that, The laser (31) is a narrow linewidth laser with a linewidth of 3 kHz and a center wavelength of 1549.972 nm; the fiber grating filter (38) has a bandwidth of 0.08 nm and a center wavelength of 1550.06 nm; the dense wavelength division multiplexer (39) has a center wavelength of 1549.972 nm.

5. The multi-dimensional communication and sensing system integrating an optical transmission network and BOTDR / DAS distributed sensing according to claim 1 or 2, characterized in that, The splitting ratios of the first coupler (32), the third coupler (310), and the fourth coupler (315) are all 50:50; the splitting ratio of the second coupler (312) is 20:

80.

6. The multi-dimensional communication and sensing system integrating an optical transmission network and BOTDR / DAS distributed sensing according to claim 1 or 2, characterized in that, The microwave signal emitted by the microwave signal source (321) sweeps the frequency in the range of 11.12-11.22GHz with a step of 4MHz; the center frequency of the bandpass filter (317) is 300 MHz and the bandwidth is 100 MHz.

7. The multi-dimensional communication and sensing system integrating optical transmission network and BOTDR / DAS distributed sensing according to claim 2, characterized in that, The OTN transmission subsystem (1) adopts a single-channel rate of 100 Gbit / s OTN configuration, based on the polarization multiplexing QPSK coherent reception modulation format, and operates in the C band; it adopts an 88-wavelength DWDM scheme with a channel spacing of 50 GHz, and each wavelength channel independently carries different data services.

8. The multi-dimensional communication and sensing system integrating optical transmission network and BOTDR / DAS distributed sensing according to claim 3, characterized in that, The upper branch light serves as the probe pulse light, and the lower branch light serves as the local oscillator light for the BOTDR and DAS, respectively; the probe pulse light is represented as: ； In the formula, Indicates the amplitude of the probe pulse light; Indicates the frequency of the laser (31); t represents the frequency shift introduced by the acousto-optic modulator (33); t represents time. Indicates the initial phase of the probe pulse; The local oscillator light of the BOTDR and DAS are respectively represented as: and : ； ； In the formula, and These represent the amplitudes of the Brillouin and Rayleigh oscillators, respectively. , These represent the initial phases of the Brillouin and Rayleigh oscillators, respectively. The total optical field of the backscattered signal light returned by the fiber optic link (2) is expressed as: ； In the formula, , and These are Rayleigh scattering, Brillouin-Stokes scattering, and Brillouin anti-Stokes scattering, respectively, where: ； ； ； in , and These represent the amplitudes of Rayleigh scattering, Brillouin scattering Stokes ray, and Brillouin scattering anti-Stokes ray, respectively. Indicates Brillouin frequency shift; , , These are the phase differences between Rayleigh scattering, Brillouin scattering Stokes ray, Brillouin scattering anti-Stokes ray, and their respective local oscillator rays; , , These are the initial phases of Rayleigh scattering, Brillouin-Stokes scattering, and Brillouin-anti-Stokes scattering, respectively.

9. The multi-dimensional communication and sensing system integrating optical transmission network and BOTDR / DAS distributed sensing according to claim 8, characterized in that, The optical signal output by the first balanced detector (311) is represented as follows: ； The optical signal output by the second balanced photodetector (316) is represented as follows: ； In the formula, and These represent the power of Rayleigh scattering and spontaneous Purlyan scattering, respectively. Indicates proportional to; and These represent the power of the Brillouin oscillator and the Rayleigh oscillator, respectively.

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