A communication and sensing integrated system

Abstract

This invention belongs to the technical field of optical fiber communication and distributed optical fiber sensing. It discloses an integrated communication and sensing system, in which the transmitting end of the communication branch generates communication service light; the transmitting end of the sensing branch generates a probe light pulse with a wavelength greater than the S-band, and its center wavelength is located within the guard band of the communication service light; a wavelength multiplexer combines the two optical signals for transmission in the same optical fiber, with the S-band communication service light transferring energy to the probe light pulse based on stimulated Raman scattering; a wavelength demultiplexer separates the backscattered Rayleigh echo and the communication service light; the receiving end of the communication branch, in conjunction with a coherent receiver, can recover the original data based on the communication service light; and the receiving end of the sensing branch, in conjunction with a coherent receiver, can obtain anomaly information of the optical fiber link based on the backscattered Rayleigh echo. Based on this design, long-distance optical fiber detection can be achieved without affecting communication services, with low optical fiber resource consumption and system cost.

Description

Technical Field

[0001] This invention belongs to the technical field of optical fiber communication and distributed optical fiber sensing, and more specifically, relates to an integrated communication and sensing system. Background Technology

[0002] With the increasing demand for ultra-high capacity transmission and long-distance condition sensing in backbone networks, submarine optical cables, and transportation infrastructure, fiber optic communication systems and distributed optical fiber sensing systems (DAS systems) have been widely applied. S+C+L broadband optical communication systems can significantly improve the communication capacity of a single optical fiber by simultaneously utilizing the spectral resources of the S-band, C-band, and L-band; while DAS systems can use narrow linewidth probe light pulses and backscattered Rayleigh signals to realize the sensing of vibration, strain, and acoustic events along the optical fiber link.

[0003] Communication systems primarily focus on the capacity of service signals, optical signal-to-noise ratio (SNR), and bit error rate performance. DAS systems, on the other hand, primarily focus on the peak power of the probe pulse, the SNR of the scattered signal, and the sensing distance. Since the two systems use different optical signals, to avoid interference between the probe optical signal and the communication service optical signal, existing communication systems and DAS systems are typically deployed independently, using different fiber optic links. Furthermore, to improve the detection distance of DAS systems, high-power distributed Raman pumping is usually introduced into the sensing fiber optic link. This utilizes stimulated Raman scattering (SRS) to amplify the backscattered Rayleigh echo along the line, compensating for signal attenuation over long distances and thus improving the echo SNR. However, independent deployment increases fiber optic resource consumption, and adding high-power Raman pump sources and related control units also increases system costs.

[0004] Therefore, how to achieve long-distance fiber optic detection without affecting communication services and with low fiber optic resource consumption and system cost is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention provides an integrated communication and sensing system, the purpose of which is to achieve long-distance fiber optic detection with low fiber optic resource consumption and system cost without affecting communication services.

[0006] The present invention provides an integrated communication and sensing system, which includes a communication branch, a sensing branch and a coherent receiver: the communication branch includes a communication branch transmitter, a wavelength multiplexer, a wavelength demultiplexer and a communication branch receiver, the sensing branch includes a sensing branch transmitter and a sensing branch receiver, and the sensing branch multiplexes the wavelength multiplexer and wavelength demultiplexer of the communication branch. The communication branch transmitter is used to generate communication service light covering the S-band, C-band and L-band, and to set guard bands at the boundaries of different bands without allocating communication service light, and to pre-emphasize the power of the communication service light so that the optical transmission power increases as the wavelength decreases; The transmitting end of the sensing branch is used to generate a probe light pulse with a wavelength greater than that of the S-band communication service light, and the center wavelength of the probe light pulse is located in the guard band of the communication service light to avoid direct crosstalk between the communication service light and the probe light pulse. A wavelength multiplexer is used to combine and transmit communication service light and probe light pulses in the same optical fiber. During the combined transmission, the S-band communication service light transfers energy to the probe light pulse based on stimulated Raman scattering. A wavelength demultiplexer is used to receive optical signals and separate the backscattered Rayleigh echo of the probe optical pulse from the communication service optical in different bands. The communication branch receiver is used to denoise and amplify the communication service light before inputting it into the coherent receiver. The receiving end of the sensing branch is used to denoise and amplify the backscattered Rayleigh echo before inputting it into the coherent receiver. Coherent receivers are used to acquire anomaly information of fiber optic links based on backscattered Rayleigh echoes and to recover the original data carried by communication service light.

[0007] Overall, compared with the prior art, the technical solutions conceived in this invention have the following beneficial effects.

[0008] 1. Based on existing communication branches, this invention sets up guard bands at the boundaries of different bands without allocating communication service light, and multiplexes the probe pulse into the communication guard band, enabling the communication service light and probe light to be transmitted on the same fiber. This saves fiber optic space. Furthermore, since the probe light is located in the communication guard band, crosstalk between the probe light and the communication service light during co-fiber transmission is reduced, thus minimizing the impact on the communication service. In addition, due to stimulated Raman scattering (SMR) in long-distance optical fibers (i.e., energy transfer from the short-wavelength side to the long-wavelength side), this invention uses a probe light with a wavelength longer than the S-band communication service light. During co-fiber transmission, based on SMR, the S-band communication service light can transfer energy to the longer-wavelength probe light, allowing the probe pulse to gain distributed gain during propagation. This gain increases the effective power of the probe pulse in long-distance links and enhances the backscattered Rayleigh echo intensity, thereby increasing the fiber optic detection distance without additional distributed Raman pumping or reducing the power of the distributed Raman pump. In summary, this invention eliminates the need to lay additional sensing optical fibers to improve the utilization of existing optical fiber resources. It utilizes communication light to provide sensing gain, thereby reducing the demand for independent sensing pumps. It can maintain communication service performance and does not change the basic architecture of the original main communication link. In other words, it can achieve long-distance optical fiber detection with low optical fiber resource consumption and system cost without affecting communication services. It can be used in scenarios that require communication and along-line status awareness, such as long-span backbone networks, submarine optical cables, oil and gas pipelines, power optical cables, traffic tunnels, and urban utility tunnels.

[0009] 2. Furthermore, it is preferable to place the center wavelength of the probe light pulse in the guard band of the right boundary of the L-band. This ensures that all communication service light in the S-band, C-band, and L-band is located on the short wavelength side of the probe light pulse, maximizing the distributed gain provided by the communication service light to the probe light pulse through stimulated Raman scattering, thereby further improving the sensing distance and the signal-to-noise ratio of the backscattered Rayleigh echo, while avoiding direct crosstalk between the communication service light and the probe light pulse.

[0010] 3. Furthermore, a preferred structural design for the sensing branch and the communication branch is provided, based on which the signal-to-noise ratio of optical signals transmitted in the optical fiber link can be improved.

[0011] 4. Furthermore, erbium-doped fiber amplifiers are used in the C-band and L-band of the communication branch, while thulium-doped fiber amplifiers or semiconductor optical amplifiers are used in the S-band. This allows for the selection of matching amplification media based on the gain characteristics of different bands, thereby enabling S+C+L ultra-wideband communication service optical to achieve consistent high-performance amplification across the entire band, improving the transmission signal-to-noise ratio and long-distance transmission capability of the communication branch.

[0012] 5. Furthermore, with the optimization objective of maximizing the stimulated Raman scattering gain of the probe light pulse and the power spectral flatness of the communication service light in each band at the receiver, the optimal power pre-emphasis vector is determined. This maximizes the distributed gain of stimulated Raman scattering provided by the S-band communication service light to the probe light pulse, thereby extending the sensing distance without adding a dedicated Raman pump light source and achieving joint optimization of communication performance and sensing performance.

[0013] 6. Further, using the pre-emphasized vector To optimize the variables and construct a suitable fitness function, a particle swarm optimization algorithm is used to find the optimal variables. This can be used to quickly converge to a globally better solution for multidimensional and non-convex joint optimization problems of pre-emphasized vectors by leveraging the algorithm's swarm collaborative search capability, reducing the solution complexity, and supporting online closed-loop iteration and real-time fine-tuning, thereby adapting to dynamic adjustments based on changes in link parameters and synesthesia performance requirements.

[0014] 7. Furthermore, when a relay station is present, the optical monitoring channel and the probe optical pulses reuse the same wavelength channel, which can save channel space. Attached Figure Description

[0015] Figure 1 This is a system architecture diagram of an integrated communication and sensing system according to an embodiment of the present invention.

[0016] Figure 2 This is a schematic diagram of the sensing branch in one embodiment of the present invention.

[0017] Figure 3 This is a complete flowchart of the sensing digital signal processing flow in one embodiment of the present invention.

[0018] Figure 4 This is a time-spectrum diagram of a linear chirped sensing pulse in one embodiment of the present invention.

[0019] Figure 5 This is a schematic diagram of the communication branch structure in one embodiment of the present invention.

[0020] Figure 6 This is a complete flowchart of the communication digital signal processing flow in one embodiment of the present invention.

[0021] Figure 7 This is a schematic diagram of the structure of a coherent receiver according to an embodiment of the present invention.

[0022] Figure 8 This is a schematic diagram of power pre-emphasis on communication service optical signals in one embodiment of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0024] Example 1.

[0025] This invention provides an integrated communication and sensing system, such as Figure 1 The diagram shown is a system architecture diagram of an integrated communication and sensing system according to an embodiment of the present invention. The integrated communication and sensing system includes a communication branch, a sensing branch, and a coherent receiver. The communication branch includes a communication branch transmitter, a wavelength multiplexer, a wavelength demultiplexer, and a communication branch receiver. The sensing branch includes a sensing branch transmitter and a sensing branch receiver, and the sensing branch multiplexes the wavelength multiplexer and wavelength demultiplexer of the communication branch.

[0026] The communication branch transmitter is used to generate communication service light covering the S-band, C-band and L-band, and to set guard bands at the boundaries of different bands where no communication service light is allocated. It also performs power pre-emphasis on the communication service light to compensate for the spectral tilt caused by stimulated Raman scattering and nonlinear effects during the transmission of the communication service light. Specifically, the power pre-emphasis operation increases the transmit power as the wavelength decreases. The transmitting end of the sensing branch is used to generate probe light pulses for communication service light with wavelengths greater than those of the S-band, and the center wavelength of the probe light pulse is located in the guard band of the communication service light to avoid direct crosstalk between the communication service light and the probe light pulse. A wavelength multiplexer is used to combine and transmit communication service light and probe light pulses in the same optical fiber. During the combined transmission, the S-band communication service light transfers energy to the probe light pulse based on stimulated Raman scattering. A wavelength demultiplexer is used to receive optical signals and separate the backscattered Rayleigh echo of the probe optical pulse from the communication service optical in different bands. The communication branch receiver is used to denoise and amplify the communication service light before inputting it into the coherent receiver. The receiving end of the sensing branch is used to denoise and amplify the backscattered Rayleigh echo before inputting it into the coherent receiver. Coherent receivers are used to acquire anomaly information of fiber optic links based on backscattered Rayleigh echoes and to recover the original data carried by communication service light.

[0027] In the above integrated communication and sensing system, the communication branch transmitter generates S-band, C-band, and L-band communication service light, which is then combined into a broadband communication signal using a wavelength multiplexer. The sensing branch transmitter generates DAS probe light pulses with a center wavelength located within the guard interval. The communication and sensing branches share the same wavelength multiplexer, transmission fiber, and wavelength demultiplexer. After multiplexing, both types of optical signals enter the same transmission fiber. During transmission, the S-band communication light provides distributed gain to the DAS probe light through the stimulated Raman effect. The communication branch receiver receives the communication signal, and the sensing branch receiver receives the DAS backscattered signal.

[0028] In practical applications, the above integrated communication and sensing systems can be deployed at both ends of the optical fiber, designated as System A and System B, respectively. System A can transmit and receive optical signals, as can System B. Assuming System A transmits a signal, the wavelength multiplexer in System A combines the communication service light and the probe light pulse for transmission in the same optical fiber. The communication service light is transmitted forward to System B, where it passes through the wavelength demultiplexer, communication tributary receiver, and coherent receiver to ultimately recover the original data sent by System A. The backscattered Rayleigh echo generated by the probe light pulse at an anomalous node in the optical fiber returns to System A, where the wavelength demultiplexer, communication tributary receiver, and coherent receiver extract the anomalous information of the optical fiber link.

[0029] In one embodiment, the communication service optical light in the S-band is preferably located between 1470nm and 1525nm, the communication service optical light in the C-band is preferably located between 1530nm and 1565nm, and the communication service optical light in the L-band is preferably located between 1570nm and 1625nm.

[0030] In one embodiment, the center wavelength of the probe light pulse is located in the guard band of the right boundary of the L-band. For example, 1625nm ± 1nm is set as the guard band of the right boundary of the L-band, and the center wavelength of the probe light pulse is 1625nm ± 1nm. It should be noted that the center wavelength of the DAS probe light is not limited to 1625 nm, and can also be set in other guard bands.

[0031] like Figure 2 The diagram shown is a schematic diagram of the sensing branch in one embodiment of the present invention.

[0032] The transmitting end of the sensing branch includes a narrow linewidth laser 1_1, an optical fiber coupler 2, a modulator 3, a first erbium-doped fiber amplifier (EDFA) 4, and a first optical bandpass filter 5; wherein: A narrow-linewidth laser 1_1 is used to generate stable continuous light and input it into an optical fiber coupler 2; for example, its wavelength can be selected to be around 1625 nm. Fiber optic coupler 2 is used to distribute the probe light and the local oscillator light (LO); Modulator 3 is used to modulate the probe light into a probe light pulse; for example, an acousto-optic modulator, an electro-optic modulator, or an IQ modulator can be selected; the communication modulation format is not limited to QPSK, and 16QAM, 64QAM, probabilistic shaped QAM, OFDM, or other coherent modulation formats can also be used.

[0033] The first erbium-doped fiber amplifier 4 is used to amplify the probe light pulse and input it into the first optical bandpass filter 5; The first optical bandpass filter 5 is used to filter out amplified spontaneous emission noise and communication crosstalk. After filtering out the noise, the optical fiber circulator inputs the wavelength multiplexer to be combined with the communication service optical into the same optical fiber for transmission. The receiving end of the sensing branch includes a second optical bandpass filter 6 and a second erbium-doped fiber amplifier 7, wherein, The second optical bandpass filter 6 is used to filter out noise and communication crosstalk from the back Rayleigh scattering echo that has been demultiplexed by the wavelength demultiplexer and output by the fiber optic circulator before inputting it into the second erbium-doped fiber amplifier 7. The second erbium-doped fiber amplifier 7 is used to amplify the received backscattered Rayleigh echo before inputting it into the coherent receiver 8; The coherent receiver 8 is used to perform coherent mixing and photoelectric conversion based on the backscattered Rayleigh echo and the local oscillator light to output an electrical signal, which is then processed digitally to analyze the fiber optic link anomaly information.

[0034] The working process of the above sensor branch is as follows: A narrow-linewidth laser 1_1 outputs continuous light, which is split into two paths by an optical fiber coupler 2: one path serves as a probe beam, and the other as a local oscillator beam. The probe beam enters a modulator 3 and is modulated into a probe pulse. This probe pulse is amplified by a first erbium-doped fiber amplifier 4, and then filtered by an optical bandpass filter 5 to remove amplified spontaneous emission (ASE) noise and possible communication crosstalk before being injected into the sensing fiber link. As the probe pulse propagates in the sensing fiber, the backscattered Rayleigh echo generated along the way returns along the original path. The echo first passes through an optical bandpass filter 6 to remove noise, and then is amplified by a second erbium-doped fiber amplifier 7. The amplified echo, along with the other local oscillator beam from coupler 2, enters a coherent receiver 8. Within the receiver, coherent mixing and photoelectric conversion are performed, outputting an electrical signal containing vibration / acoustic event information. This electrical signal is then digitally demodulated and processed to extract the location and waveform information of vibration, strain, and acoustic events along the fiber link.

[0035] Optionally, the probe pulse can be a narrow pulse, a chirped pulse, or a coded pulse. When using a chirped pulse, the receiver obtains spatial resolution and signal-to-noise ratio gain through matched filtering or pulse compression; when using a coded pulse, the average transmit power can be improved without reducing spatial resolution through correlation decoding.

[0036] like Figure 3 The diagram shows a complete flowchart of the digital signal processing flow for sensing in one embodiment of the present invention. The transmitter inputs the chirped pulse into the modulator and may add a time window to reduce sidelobes; the window type can be a Hanning window, a Gaussian window, etc. Simultaneously, modulator frequency response pre-compensation and low-pass filtering are performed. The receiver performs matched filtering or pulse compression on the echo signal, followed by spectrum division, rotation vector superposition, movement vector summation, and phase difference to obtain the DAS sensing signal. This process can further improve the echo signal-to-noise ratio and positioning accuracy based on the Raman gain obtained from the probe light (e.g., with a center wavelength of 1625 nm).

[0037] like Figure 4 The image shows the time-frequency spectrum of a linearly chirped sensing pulse in one embodiment of the present invention. In practice, the DAS probe pulse can be a single-frequency narrow pulse, a linearly chirped pulse, a phase-coded pulse, or a frequency-coded pulse. For linearly chirped pulses, the receiver can achieve pulse compression through matched filtering; for coded pulses, the receiver can improve the detection signal-to-noise ratio through correlation decoding. Due to the frequency chirping characteristics, the time-domain waveform and spectrum of the sensing pulse exhibit similarity. In the time domain, the windowing process causes a certain roll-off on the rising and falling edges of the pulse, suppressing the cross-phase modulation effect and reducing interference with communication services. In the frequency domain, windowing suppresses the sidelobes of the compressed pulse, avoiding spatial leakage. Simultaneously, the pulse spectrum division can be used to implement a vector superposition algorithm, reducing interference fading.

[0038] like Figure 5 The diagram shown is a structural schematic of a communication branch in one embodiment of the present invention.

[0039] The communication branch transmitter includes an S-band transmitter, a C-band transmitter, and an L-band transmitter. Each type of transmitter includes a communication laser 1_2, a coherent optical communication modulator 9, an optical amplifier 10, and a first variable optical attenuator 11_1. Communication laser 1_2 is used to generate continuous wave optical carriers for the corresponding wavelength bands and input them into coherent optical communication modulator 9; each wavelength band has at least one communication wavelength channel; "Indicates the communication wavelengths of the S, C, and L bands; The coherent optical communication modulator 9 is used to load the electrical data to be transmitted onto the optical carrier and input it into the optical amplifier 10; for example, a dual-biased IQ modulator can generally be selected to load communication formats such as QPSK, QAM or probabilistic shaped QAM. Optical amplifier 10 is used to amplify the power of the modulated optical signal to compensate for the loss of subsequent devices; The first variable optical attenuator 11_1 is used in conjunction with the wavelength selection switch WSS to adjust the power of each wavelength channel so as to realize the input wavelength multiplexer 12 after pre-emphasis at the transmitter. The optical signals emitted by all the transmitting ends of all bands are combined into the same optical fiber in the wavelength multiplexer 12 for transmission, and then arrive at the wavelength demultiplexer for separation. The communication branch receiver includes an S-band receiver, a C-band receiver, and an L-band receiver. Each type of receiver includes a preamplifier 14 and a second variable optical attenuator 11_2. The preamplifier 14 is used to acquire the communication service optical of the corresponding band separated by the wavelength demultiplexer and amplify its power to improve the receiving sensitivity; its structure is the same as that of the optical amplifier 10 in the corresponding band transmitter. The second variable optical attenuator 11_2 is used to adjust the optical crosstalk before inputting it into the coherent receiver 8; The coherent receiver 8 is used to demodulate and process the communication service light to recover the original communication data.

[0040] Preferably, the optical amplifiers 10 in both the C-band and L-band transmitters are erbium-doped fiber amplifiers (EDFAs), and correspondingly, the preamplifiers 14 in both the C-band and L-band receivers are also erbium-doped fiber amplifiers; the optical amplifiers 10 in the S-band transmitter are thulium-doped fiber amplifiers (TDFAs) or semiconductor optical amplifiers, and correspondingly, the preamplifiers 14 in the S-band receiver are also thulium-doped fiber amplifiers or semiconductor optical amplifiers.

[0041] The working process of the above communication branch is as follows: The communication laser outputs a continuous-wave optical carrier of the corresponding wavelength according to the band requirements, which enters the coherent optical communication modulator 9. In the modulator 9, the high-speed electrical data to be transmitted is loaded onto the optical carrier to generate modulated optical signals in formats such as QPSK, QAM, or probabilistic shaped QAM. The modulated optical signal is amplified by the optical amplifier 10 to compensate for the insertion loss of subsequent devices. The amplified signal enters the variable optical attenuator 11_1, which, together with the wavelength selection switch (WSS, not shown in the figure), finely adjusts the power of each wavelength channel to achieve pre-emphasis at the transmitter, in order to compensate for the spectral tilt caused by the transfer of short-wavelength power to long-wavelength power due to nonlinear effects such as stimulated Raman scattering (SRS) in the subsequent transmission link. The pre-emphasized wavelength signals then enter the wavelength multiplexer 12 to synthesize a multi-wavelength WDM signal and further adjust the spectral flatness. After the synthesized S+C+L broadband WDM signal reaches the receiver through the transmission fiber, it first enters the wavelength demultiplexer 13 to separate the mixed multi-wavelength signal into independent channels according to wavelength. The signal from each channel is then amplified by preamplifier 14 to increase signal power and improve receiver sensitivity. The amplified signal is then sent to coherent receiver 8 for demodulation and data processing to recover the original communication data.

[0042] like Figure 6 The diagram shows a complete flowchart of the communication digital signal processing flow in one embodiment of the present invention. The transmitting end sequentially performs data input, modulation format mapping, probability shaping, pulse shaping, IQ skew compensation, modulator frequency response pre-compensation, and spectrum pre-emphasis. The receiving end sequentially performs matched filtering, clock recovery, resampling, dispersion / nonlinearity compensation, adaptive equalizer, and carrier recovery.

[0043] like Figure 7 The diagram shown is a structural schematic of a coherent receiver according to an embodiment of the present invention.

[0044] The coherent receiver 8 includes a polarization beamsplitter, a 90° optical mixer, a balanced detector, an analog-to-digital converter, and a digital signal processing unit (DSP). Sensing or communication signals are coherently mixed with the local optical locus (LO) in the mixer, and then fed into the DSP after balanced detection and analog-to-digital conversion. For communication signals, the DSP recovers the data symbols; for DAS signals, the DSP calculates the phase difference or phase change between adjacent distance cells to obtain vibration and acoustic information along the line.

[0045] like Figure 8 The diagram shown is a schematic diagram of power pre-emphasis on communication service optical signals in one embodiment of the present invention.

[0046] Power pre-emphasis in communication optical signals refers to the process at the transmitting end where, based on the fiber loss characteristics and cross-band power transfer patterns caused by nonlinear effects such as stimulated Raman scattering (SRS) in the transmission link, the initial transmit power of each wavelength channel is configured in a non-flat, inverse way before entering the fiber using methods such as variable optical attenuators, wavelength selective switches (WSS), or direct laser modulation. Typically, the optical power of short-wavelength channels (such as the short-wavelength side of S-band and C-band) is relatively increased, while the optical power of long-wavelength channels (such as L-band) is relatively decreased, resulting in a preset power distribution in the fiber-entry spectrum that is opposite to the power tilt trend of the link. After long-distance transmission, the energy transferred out by the short-wavelength side due to the SRS effect cancels out the energy gained by the long-wavelength side, thereby achieving spectral power flatness equalization and optical signal-to-noise ratio (OSNR) consistency optimization for multi-wavelength signals at the receiving end or relay node. This ensures the transmission performance and bit error rate of ultra-high-capacity S+C+L ultra-wideband communication systems without significantly increasing system nonlinear impairment.

[0047] like Figure 8 As shown, the S-band communication light is preferably located between 1470nm and 1525nm, the C-band communication light is preferably located between 1530nm and 1565nm, and the L-band communication light is preferably located between 1570nm and 1625nm. The DAS probe light is preferably located near 1625nm. For example, in a single-span long-distance transmission link, the transmitter forms a communication service light covering 1470nm to 1625nm, pre-emphasizes the communication spectrum, and establishes a guard band near 1625nm. The DAS probe branch generates a 1625nm probe pulse, which is amplified by an L-band EDFA and filtered by an optical bandpass before being combined with the communication light and entering the transmission fiber. During transmission, the S-band communication service light provides stimulated Raman distributed gain to the 1625nm DAS probe light. The receiver recovers the S / C / L communication data from the communication demultiplexing port and receives the Rayleigh scattering echo from the DAS receiving port. By adjusting the pre-emphasis of S-band communication power, the DAS echo signal-to-noise ratio can be improved while meeting the requirements for communication bit error rate.

[0048] In this invention, the wavelength of the probe light pulse is longer than that of the S-band. The S-band communication service light not only carries communication services but also provides distributed gain to the longer-wavelength DAS probe light through the stimulated Raman effect. Thus, the energy transfer effect that would otherwise need to be compensated for in the communication system is used to enhance the sensing signal, achieving synergistic optimization of communication and sensing.

[0049] The following example illustrates a specific pre-emphasis method, using the detection light pulse center wavelength located near 1625nm as an example.

[0050] Let the pre-emphasis vector be... , This represents the channel power boost applied to the i-th communication channel, in dB. This represents the total number of communication channels. The above pre-emphasis vectors must simultaneously satisfy the following two constraints: Constraint ① (ISRS Inter-channel constraint): Compensates for spectral tilt caused by inter-channel stimulated Raman scattering (ISRS) between the S+C+L communication channels, so as to flatten the power spectrum of the S, C, and L bands at the receiver. Constraint ② (Communication data constraint on DAS gain): Make the communication data light (especially the S-band) act as an equivalent distributed Raman pump to provide line-of-sight Raman gain to the DAS probe pulse at 1625 nm, thereby improving the sensing distance and optical signal-to-noise ratio (OSNR).

[0051] The optimal power pre-emphasis vector can be determined by optimizing the stimulated Raman scattering gain of the probe light pulse and the power spectral flatness of the communication service light in each band at the receiver.

[0052] Specifically, the optimal solution between the two can be obtained through an iterative algorithm.

[0053] In this embodiment, a pre-emphasis vector can be used. To optimize the variable, its value range can be... The particle swarm optimization algorithm is used to find the optimal variables. The fitness function used in the particle swarm optimization algorithm is: (1); The first item corresponds to constraint ① (power spectrum flatness score), the second item corresponds to constraint ② (stimulated Raman scattering gain score of the probe light pulse), and the third item suppresses the rise of total emission power. For example, weighting coefficients It can be adjusted online according to the user's preferred synesthetic performance.

[0054] The power spectrum flatness can be expressed as: (2); In the formula, The span length of the transmission optical fiber, This represents the first digit after applying the pre-emphasis vector T. The communication channels span length Power integration within, through the first The power of each communication channel at different locations is obtained by integrating the power of each channel. This is the unevenness threshold; No. Each communication channel is located at the fiber optic position. Power at the location It can be represented as: (3); (4); In the formula, For the first Attenuation coefficient of each communication channel Represents the Raman gain efficiency function. They represent the first The communication channel and the first The frequency of each communication channel, Represents a symbolic variable, when Shortwave supplies power to this channel. ,when This channel outputs energy to long waves. , This indicates the input power of each channel after pre-emphasis. This is the reference transmit power.

[0055] Detecting the power along the path of the optical pulse It can be represented as: (5); Raman gain of communication service optical to DAS pulse Represented as: (6); In the formula, the effective length of the optical fiber is... , To detect the attenuation coefficient of the optical pulse, For the target gain value (e.g.) It can be set to greater than ), To detect the frequency of the light pulse.

[0056] During the execution of the particle swarm optimization algorithm, let the number of particles be... (recommend ), No. The particle in the first The position and velocity of the generation are respectively and Individual optimal Global Optimum The iterative equation is: ; ; Specific settings: Inertia weight The factor is 0.4 (and may gradually decrease), representing the cognitive / social learning factor. , They are independent, uniformly random numbers; During each generation of evaluation, the particles Substituting into equations (3) and (5) above, along Numerical integration (step size recommended: 100m) yields... and Then substitute into equation (1) to calculate fitness. When the iteration number reaches (recommend )or The process terminates when the set value is true for a certain number of consecutive generations, and outputs the globally optimal pre-emphasis curve. .

[0057] Online closed-loop update: The data is sent to the transmitter's WSS; the system synchronously monitors the spectrum unevenness at the receiver during operation. Compared with the backscattered Rayleigh echo SNR of DAS, the two residuals drive PSO for few generations of fine-tuning or simplified one-dimensional gradient descent, and are updated in real time. This constitutes a sensory-based joint closed-loop control.

[0058] In practical implementation, system A is set up at one station on the communication link and system B is set up at the other station. Both system A and system B are integrated communication and sensing systems as described above. When system A sends an optical signal to system B through an optical fiber, the communication service light generated by the transmitter of the communication branch in system A and the detection light pulse generated by the transmitter of its sensing branch are combined and transmitted in the same optical fiber through its wavelength multiplexer. The optical data of the communication service is transmitted forward to system B. After passing through the wavelength demultiplexer, communication branch receiver and coherent receiver in system B, the original data sent by system A is finally recovered in system B. The backscattered Rayleigh echo generated by the probe optical pulse at the abnormal node of the optical fiber returns to system A. The abnormal information of the optical fiber link is extracted by the wavelength demultiplexer, the communication branch receiver and the coherent receiver in system A.

[0059] In one embodiment, a relay station exists in the communication link as an intermediate node for periodically amplifying the attenuated optical signal. The relay station typically includes optical amplifiers (such as erbium-doped fiber amplifiers (EDFAs) and distributed Raman amplifiers), dispersion compensation modules, optical monitoring channel (OSC) add / drop units, and corresponding optical layer management units. Its main function is to perform power compensation and signal regeneration on the S+C+L ultra-wideband communication service optical signal without photoelectric conversion, thereby overcoming the limitations on transmission distance imposed by fiber attenuation, nonlinear effects, and dispersion accumulation. Simultaneously, the relay station uses the OSC channel to exchange network management information with upstream and downstream stations, report fault alarms, and distribute remote configurations, ensuring the controllability and reliability of the optical network's operation and maintenance.

[0060] In the application scenario of co-fiber communication and sensing provided by this invention, when system A sends an optical signal to system B through a relay station, the relay station is used to forward the optical signal sent by system A to system B, amplify the communication service optical signal therein, and realize network management information interaction with upstream and downstream stations through the optical monitoring channel; wherein, the optical monitoring channel and the probe optical pulse reuse the same wavelength channel. For example, the 1625 nm DAS probe light can be reused as the optical monitoring channel OSC. The system utilizes the isolation characteristics of the 1625 nm band for communication service optical signals to achieve along-line status sensing without occupying the S / C / L main communication service spectrum.

[0061] It should be noted that this invention is not limited to single-core unidirectional links, but can be extended to single-core bidirectional, dual-core bidirectional, multi-core optical fibers, hollow-core optical fibers, and submarine transmission links.

[0062] In summary, the integrated communication and sensing solution proposed in this invention, based on existing broadband communication systems, incorporates a DAS detection branch into the guard band of the communication service light. It utilizes the S-band communication service light to generate distributed Raman gain on the DAS detection light, while maintaining communication performance through spectral pre-emphasis. This solution improves fiber optic resource utilization, reduces the deployment cost of the sensing system, and enhances long-distance DAS sensing capabilities, demonstrating significant engineering application value. It can be applied to the fields of fiber optic communication and distributed fiber optic sensing, and can be deployed in existing backbone communication networks, submarine optical cables, oil and gas pipeline accompanying optical cables, power communication optical cables, railway and highway optical cables, urban rail transit tunnels, underground integrated pipe corridors, and large data center interconnection links. It is used to provide high-capacity communication services while simultaneously monitoring vibration, intrusion, fiber breakage, stress, and acoustic events along ultra-long distances.

[0063] The technical features of the embodiments described above can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. It should be noted that the terms "in one embodiment," "for example," and "again" in this invention are intended to illustrate the invention and are not intended to limit the invention.

[0064] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. An integrated communication and sensing system, characterized in that, It includes a communication branch, a sensing branch, and a coherent receiver: the communication branch includes a communication branch transmitter, a wavelength multiplexer, a wavelength demultiplexer, and a communication branch receiver; the sensing branch includes a sensing branch transmitter and a sensing branch receiver, and the sensing branch multiplexes the wavelength multiplexer and wavelength demultiplexer of the communication branch. The communication branch transmitter is used to generate communication service light covering the S-band, C-band and L-band, and to set guard bands at the boundaries of different bands without allocating communication service light, and to pre-emphasize the power of the communication service light so that the optical transmission power increases as the wavelength decreases; The transmitting end of the sensing branch is used to generate a probe light pulse with a wavelength greater than that of the S-band communication service light, and the center wavelength of the probe light pulse is located in the guard band of the communication service light to avoid direct crosstalk between the communication service light and the probe light pulse. A wavelength multiplexer is used to combine and transmit communication service light and probe light pulses in the same optical fiber. During the combined transmission, the S-band communication service light transfers energy to the probe light pulse based on stimulated Raman scattering. A wavelength demultiplexer is used to receive optical signals and separate the backscattered Rayleigh echo of the probe optical pulse from the communication service optical in different bands. The communication branch receiver is used to denoise and amplify the communication service light before inputting it into the coherent receiver. The receiving end of the sensing branch is used to denoise and amplify the backscattered Rayleigh echo before inputting it into the coherent receiver. Coherent receivers are used to acquire anomaly information of fiber optic links based on backscattered Rayleigh echoes and to recover the original data carried by communication service light.

2. The integrated communication and sensing system as described in claim 1, characterized in that, The center wavelength of the probe light pulse is located in the guard band of the right boundary of the L-band.

3. The integrated communication and sensing system as described in claim 2, characterized in that, The communication service optical wavelengths in the S-band are between 1470nm and 1525nm, those in the C-band are between 1530nm and 1565nm, and those in the L-band are between 1570nm and 1625nm. The center wavelength of the probe light pulse is 1625nm ± 1nm.

4. The integrated communication and sensing system as described in claim 1, characterized in that, For the sensing branch: The transmitting end of the sensing branch includes a narrow-linewidth laser (1_1), an optical fiber coupler (2), a modulator (3), a first erbium-doped fiber amplifier (4), and a first optical bandpass filter (5); wherein: A narrow linewidth laser (1_1) is used to generate stable continuous light and input it into an optical fiber coupler (2). Fiber optic coupler (2) is used to distribute the probe light and the local oscillator light (LO); The modulator (3) is used to modulate the probe light into a probe light pulse; The first erbium-doped fiber amplifier (4) is used to amplify the probe light pulse and input it into the first optical bandpass filter (5). The first optical bandpass filter (5) is used to filter out amplified spontaneous emission noise and communication crosstalk, and then inputs the optical fiber circulator into the wavelength multiplexer to be combined with the communication service optical into the same optical fiber for transmission. The receiving end of the sensing branch includes a second optical bandpass filter (6) and a second erbium-doped fiber amplifier (7); wherein, The second optical bandpass filter (6) is used to filter out noise and communication crosstalk from the back Rayleigh scattering echo that has been decomposed by the wavelength demultiplexer and output by the fiber optic circulator before inputting it into the second erbium-doped fiber amplifier (7). The second erbium-doped fiber amplifier (7) is used to amplify the received back Rayleigh scattering echo and input it into the coherent receiver (8). The coherent receiver (8) is used to perform coherent mixing and photoelectric conversion based on the back Rayleigh scattering echo and the local oscillator light, and output an electrical signal before performing digital demodulation to obtain abnormal information of the optical fiber link.

5. The integrated communication and sensing system as described in claim 1, characterized in that, For communication branches: The communication branch transmitter includes an S-band transmitter, a C-band transmitter and an L-band transmitter. Each type of transmitter includes a communication laser (1_2), a coherent optical communication modulator (9), an optical amplifier (10) and a first variable optical attenuator (11_1). The communication laser (1_2) is used to generate a continuous wave optical carrier of the corresponding band and input it into the coherent optical communication modulator (9); each band has at least one communication wavelength channel; The coherent optical communication modulator (9) is used to load the electrical data to be transmitted onto the optical carrier and input it into the optical amplifier (10) to form the communication service optical; The optical amplifier (10) is used to amplify the modulated optical signal and then input it into the first variable optical attenuator (11_1). The first variable optical attenuator (11_1) is used in conjunction with the wavelength selection switch to adjust the power of each wavelength channel so that the pre-emphasis at the transmitter is input to the wavelength multiplexer (12) for multiplexing; The communication branch receiver includes an S-band receiver, a C-band receiver and an L-band receiver. Each type of receiver includes a preamplifier (14) and a second variable optical attenuator (11_2). The preamplifier (14) is used to acquire the communication service optical of the corresponding band separated by the wavelength demultiplexer and amplify the power to improve the receiving sensitivity; its structure is the same as that of the optical amplifier (10) in the corresponding band transmitter. The second variable optical attenuator (11_2) is used to adjust the optical crosstalk before inputting to the coherent receiver (8).

6. The integrated communication and sensing system as described in claim 1, characterized in that, The optical amplifiers in both the C-band and L-band transmitters are erbium-doped fiber amplifiers, and correspondingly, the preamplifiers in both the C-band and L-band receivers are also erbium-doped fiber amplifiers. The optical amplifiers in the S-band transmitters are thulium-doped fiber amplifiers or semiconductor optical amplifiers, and correspondingly, the preamplifiers in the S-band receivers are also thulium-doped fiber amplifiers or semiconductor optical amplifiers.

7. The integrated communication and sensing system as described in claim 1, characterized in that, Before power pre-emphasis is applied to the communication service light, the optimal power pre-emphasis vector is determined with the optimization objective of maximizing the stimulated Raman scattering gain of the probe light pulse and the power spectral flatness of the communication service light in each band at the receiver. , This represents the channel power boost applied to the i-th communication channel, in dB. This represents the total number of communication channels.

8. The integrated communication and sensing system as described in claim 7, characterized in that, With pre-emphasis vector To optimize the variables, a particle swarm optimization algorithm is used to find the optimal value for the variables. The fitness function used in the particle swarm optimization algorithm is... for: In the formula, These are the weighting coefficients. The unevenness threshold, The power spectrum unevenness of the received communication service light. This represents the power spectrum flatness score. For the Raman gain of the probe light pulse for communication service optical pairs, The target gain value, This represents the stimulated Raman scattering gain score of the probe light pulse; in, ； ； In the formula, This represents the first digit after applying the pre-emphasis vector T. Each communication channel spans the fiber optic cable. Power integral within, effective fiber length , To detect the attenuation coefficient of the optical pulse, Represents the Raman gain efficiency function. Indicates the first The frequency of each communication channel, Indicates the frequency of the probe light pulse. This is the reference transmit power.

9. The integrated communication and sensing system as described in claim 1, characterized in that, The communication link is also equipped with relay stations, which are used to forward the optical signals sent by the upstream station to the downstream station and amplify the communication service optical signals therein, as well as realize the network management information exchange between the upstream and downstream stations through the optical monitoring channel; wherein, the optical monitoring channel and the probe optical pulse multiplex the same wavelength channel.

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