A very low frequency disturbance perception positioning and large capacity optical fiber communication fusion device

Abstract

The application discloses a kind of very low frequency disturbance perception positioning and large-capacity optical fiber communication fusion device, and the perception positioning detection signal is fused with digital subcarrier multiplexing (DSM) communication signal by frequency division multiplexing, to improve the spectral efficiency of optical fiber communication system;Compatible with space division multiplexing and wavelength division multiplexing and other expansion mechanisms, large-capacity optical fiber communication can be realized;Based on the direct detection distributed acoustic sensing (DAS) technology of chirped pulse, very low frequency disturbance perception positioning is realized;It is suitable for all communication optical fibers, including but not limited to single-mode optical fiber, multi-core optical fiber and multi-core few-mode optical fiber;While maintaining the performance advantages of traditional DAS system, different fiber core / mode Rayleigh backscattering intensity is received by diversity using multi-dimensional multiplexing, so as to improve the signal-to-noise ratio and sensitivity of disturbance perception positioning signal.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical fiber communication technology, and more particularly to a fusion device of very low frequency disturbance sensing positioning and large capacity optical fiber communication. BACKGROUND

[0002] With the vigorous development of generative artificial intelligence, 5G, Internet of Things, cloud computing and the like, the demand for communication capacity is increasing rapidly, and the traditional standard single-mode fiber (SSMF) is limited in capacity expansion. Space-division multiplexing (SDM) has the potential to solve the problem of traditional SSMF capacity expansion, and has the advantages of reducing system cost and improving energy efficiency. In recent years, through the realization of sensing fusion by multi-core optical fiber (MCF) and multi-core few-mode fiber (MC-FMF), the existing communication optical fiber is endowed with sensing and positioning functions, which has attracted great interest. The distributed acoustic sensing (DAS) system based on Rayleigh backscattering is widely used due to its high sensitivity and spatial resolution.

[0003] However, the existing communication optical fiber sensing fusion system has the following problems: 1. The peak power of the sensing probe pulse in the single-core optical fiber sensing fusion system is limited by the non-linear effect of the optical fiber, resulting in weak Rayleigh backscattering signal, so that the signal-to-noise ratio and sensitivity of the disturbance sensing and positioning signal are limited; 2. In the multi-core / few-mode optical fiber sensing fusion system, the communication signal and the sensing signal are transmitted independently in different cores / modes, which sacrifices the spectral efficiency of the communication system, resulting in limited capacity expansion of the communication system; 3. Due to the phase noise and frequency drift of the laser, the sensing and positioning sensitivity of the coherent detection DAS system in the very low frequency band is poor, and the existing research mainly focuses on sensing and positioning external disturbances above 10Hz. The sensing and positioning of very low frequency disturbances from 0.1Hz to 10Hz is crucial for optical cable monitoring, geological exploration, natural disaster warning and the like. SUMMARY

[0004] In order to overcome the defect that the existing system cannot simultaneously realize high sensitivity very low frequency sensing and high spectral efficiency fusion of large capacity communication, the present application provides a fusion device of very low frequency disturbance sensing positioning and large capacity optical fiber communication.

[0005] To solve the above technical problems, the technical scheme of the present application is as follows:

[0006] The application provides a fusion device of very low frequency disturbance sensing positioning and large-capacity optical fiber communication, which comprises a signal input unit, a signal loop unit, a communication optical fiber, a sensing unit and a communication unit.

[0007] The output end of the signal input unit is connected with the input end of the signal loop unit; the output end of the signal loop unit is connected with the input end of the communication optical fiber and the sensing unit; and the output end of the communication optical fiber is connected with the communication unit.

[0008] The signal input unit is used for generating a common wavelength sensing fusion signal; the signal loop unit is used for receiving the common wavelength sensing fusion signal output by the signal input unit, and transmitting the received backscattering sensing fusion signal to the sensing unit and transmitting the forward light to the communication unit through the communication optical fiber; the sensing unit is used for positioning the very low frequency disturbance signal; and the communication unit is used for optical fiber communication.

[0009] Preferably, the signal input unit comprises a first laser, a first coupler, a second coupler, a chirp pulse generation module, a wavelength division multiplexer, a first optical amplification module, a first digital subcarrier multiplexing signal generation module and N digital subcarrier multiplexing signal generation units connected in sequence.

[0010] The digital subcarrier multiplexing signal generation unit comprises a narrow linewidth laser and a second digital subcarrier multiplexing signal generation module connected in sequence.

[0011] The output end of the first laser is connected with the input end of the first coupler; the output end of the first coupler is connected with the input end of the chirp pulse generation module and the first digital subcarrier multiplexing signal generation module; the output end of the chirp pulse generation module and the first digital subcarrier multiplexing signal generation module is connected with the input end of the second coupler; and the output end of the second coupler is connected with the input end of the wavelength division demultiplexer.

[0012] The input end of the wavelength division multiplexer is connected with the output end of the first digital subcarrier multiplexing signal generation unit; the output end of the Nth digital subcarrier multiplexing signal generation unit is connected with the input end of the wavelength division multiplexer; and the output end of the wavelength division multiplexer is connected with the input end of the first optical amplification module.

[0013] The output end of the first optical amplification module is connected with the input end of the signal loop unit.

[0014] Preferably, the communication optical fiber comprises but is not limited to a single-mode optical fiber, a multi-core optical fiber and a multi-core few-mode optical fiber.

[0015] Preferably, when the communication optical fiber is a single-mode optical fiber, the sensing unit is a first sensing unit; the signal loop unit is a first signal loop unit; the communication unit is a first communication unit; the first signal loop unit comprises a first circulator unit; the first circulator unit comprises a first circulator, an output end of the first circulator being connected with an input end of the single-mode optical fiber and an input end of the first sensing unit; an output end of the single-mode optical fiber being connected with an input end of the first communication unit.

[0016] Preferably, the first sensing unit comprises a second optical amplifier module, a first optical filter module, a first photoelectric detection module and a first signal demodulation module connected in sequence; an output end of the first circulator is connected with an input end of the second optical amplifier module; the first communication unit comprises a first wavelength division demultiplexer, a first local oscillator laser, a first signal receiving module and a second signal demodulation module; an output end of the single-mode optical fiber is connected with an input end of the first wavelength division demultiplexer; output ends of the first wavelength division demultiplexer and the first local oscillator laser are connected with an input end of the first signal receiving module; an output end of the first signal receiving module is connected with an input end of the second signal demodulation module.

[0017] Preferably, when the communication optical fiber is a multi-core optical fiber, the sensing unit is a second sensing unit; the signal loop unit is a second signal loop unit; the communication unit is a second communication unit; the second signal loop unit comprises a second circulator unit and a first fan-in fan-out unit; the second circulator unit comprises a first circulator array composed of a plurality of second circulators connected in sequence; an output end of each second circulator of the first circulator array is connected with an input end of the first fan-in fan-out unit; an output end of each second circulator of the first circulator array is connected with an input end of the second sensing unit; an output end of the first fan-in fan-out unit is connected with an input end of the second communication unit.

[0018] Preferably, the second sensing unit comprises a first optical combiner, a third optical amplifier module, a second optical filter module, a second photoelectric detection module and a third signal demodulation module connected in sequence; an output end of each second circulator of the first circulator array is connected with an input end of the first optical combiner; the second communication unit comprises a second fan-in fan-out unit, a second wavelength division demultiplexer, a second local oscillator laser, a second signal receiving module and a fourth signal demodulation module; an output end of the multi-core optical fiber is connected with an input end of the second fan-in fan-out unit; an output end of the second fan-in fan-out unit is connected with an input end of the second wavelength division demultiplexer; output ends of the second wavelength division demultiplexer and the second local oscillator laser are connected with an input end of the second signal receiving module; an output end of the second signal receiving module is connected with an input end of the fourth signal demodulation module.

[0019] Preferably, when the communication optical fiber is a multi-core few-mode optical fiber, the sensing unit is a third sensing unit; the signal loop unit is a third signal loop unit; the communication unit is a third communication unit; the third signal loop unit comprises a third circulator unit, a mode multiplexer and a third fan-in fan-out unit connected in sequence; the third circulator unit comprises a second circulator array composed of a plurality of third circulators connected in sequence; the output end of each third circulator of the second circulator array is connected with the input end of the mode multiplexer; the output end of each second circulator of the second circulator array is connected with the input end of the third sensing unit; the output end of the third fan-in fan-out unit is connected with the input end of the third communication unit.

[0020] Preferably, the third sensing unit comprises a second optical coupler, a fourth optical amplification module, a third optical filter module, a third optical detection module and a fifth signal demodulation module connected in sequence; the output end of each second circulator of the second circulator array is connected with the input end of the second optical coupler; the third communication unit comprises a fourth fan-in fan-out unit, a mode demultiplexer, a third wavelength division demultiplexer, a third local oscillator, a third signal receiving module and a sixth signal demodulation module; the output end of the multi-core few-mode optical fiber is connected with the input end of the fourth fan-in fan-out unit; the output end of the fourth fan-in fan-out unit is connected with the input end of the mode demultiplexer; the output end of the mode demultiplexer is connected with the input end of the third wavelength division demultiplexer; the output end of the third wavelength division demultiplexer and the third local oscillator is connected with the input end of the third signal receiving module; the output end of the third signal receiving module is connected with the input end of the sixth signal demodulation module.

[0021] Preferably, when the peak power of the co-wavelength sensing fusion signal exceeds a preset threshold, stimulated Brillouin scattering (SBS) causes very low frequency disturbance signal signal-to-noise ratio degradation; the preset threshold is:

[0022]

[0023] Wherein, A eff is the effective area of the communication optical fiber, g B is the SBS gain coefficient, L eff is the effective length of the communication optical fiber.

[0024] Compared with the prior art, the technical scheme of the present application has the following beneficial effects:

[0025] The application provides a fusion device of very low frequency disturbance sensing positioning and large-capacity optical fiber communication, wherein the signal input unit generates a common wavelength sensing fusion signal through frequency division multiplexing, so that the optical fiber space resources and frequency spectrum resources can be fully utilized, and the communication system capacity is improved; under the coordination of the communication unit and the sensing unit, the very low frequency disturbance signal can be positioned while the optical fiber communication is realized; the very low frequency disturbance sensing positioning is realized through direct detection and intensity cross-correlation demodulation, so that the high-sensitivity very low frequency disturbance sensing positioning and the large-capacity optical fiber communication can be realized at the same time. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 A structure schematic diagram of the fusion device of very low frequency disturbance sensing positioning and large-capacity optical fiber communication described in embodiment 1 is shown in the figure.

[0027] Figure 2 A structure schematic diagram of the common wavelength sensing fusion signal generation device described in embodiment 3 is shown in the figure.

[0028] Figure 3 A structure schematic diagram of the fusion device of very low frequency disturbance sensing positioning and large-capacity optical fiber communication based on a single-mode optical fiber described in embodiment 3 is shown in the figure.

[0029] Figure 4 A structure schematic diagram of the fusion device of very low frequency disturbance sensing positioning and large-capacity optical fiber communication based on a multi-core optical fiber described in embodiment 3 is shown in the figure.

[0030] Figure 5 A structure schematic diagram of the fusion device of very low frequency disturbance sensing positioning and large-capacity optical fiber communication based on a multi-core few-mode optical fiber described in embodiment 3 is shown in the figure.

[0031] Figure 6 A schematic diagram of the working principle of the DAS system described in embodiment 3 is shown in the figure.

[0032] Figure 7 A spectrum schematic diagram of the multi-wavelength sensing fusion signal described in embodiment 3 is shown in the figure.

[0033] Figure 8 A spectrum schematic diagram of the common wavelength sensing fusion signal under different system parameters described in embodiment 3 is shown in the figure. DETAILED DESCRIPTION

[0034] The drawings are only used for illustrative description, and cannot be understood as a limitation of the patent;

[0035] In order to better illustrate the embodiments, some components in the drawings may be omitted, enlarged or reduced, and do not represent the actual product size;

[0036] For those skilled in the art, it is understandable that some well-known structures in the drawings and their descriptions may be omitted.

[0037] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0038] Example 1

[0039] This embodiment provides a fusion device of very low frequency disturbance sensing positioning and large-capacity optical fiber communication, such as Figure 1 As shown, it includes a signal input unit, a signal ring unit, a communication optical fiber, a sensing unit and a communication unit;

[0040] The output end of the signal input unit is connected to the input end of the signal ring unit; the output end of the signal ring unit is connected to both the communication optical fiber and the input end of the sensing unit; the output end of the communication optical fiber is connected to the communication unit;

[0041] The signal input unit is used to generate a common-wavelength synaesthesia fusion signal; the signal ring unit is used to receive the common-wavelength synaesthesia fusion signal output by the signal input unit, and transmit the backscattered synaesthesia fusion signal to the sensing unit and transmit the forward light to the communication unit through the communication optical fiber; the sensing unit is used to locate the very low frequency disturbance signal; and the communication unit is used for optical fiber communication.

[0042] The device includes a signal input unit, a signal ring unit, a communication optical fiber, a sensing unit, and a communication unit. The signal input unit is responsible for generating a common-wavelength synaesthesia fusion signal and outputting the signal to the signal ring unit. The signal ring unit serves as an intermediate link, receiving the common-wavelength synaesthesia fusion signal from the signal input unit. The scattered light is directly sent to the sensing unit, and the forward light is sent to the communication unit via the communication optical fiber. The function of the sensing unit is to detect and locate extremely low-frequency disturbance signals, while the communication unit is responsible for performing optical fiber communication tasks. This design enables the system to simultaneously perform very low-frequency sensing detection and high-capacity data communication, improving the overall performance and efficiency of the system.

[0043] Compared to traditional multi-core / few-mode fiber synaesthesia fusion technology, this device can more effectively utilize the spatial and spectral resources of optical fibers by multiplexing communication signals and sensing signals under common wavelength channels, thereby increasing the capacity of the communication system. Compared with existing single-core fiber synaesthesia fusion solutions, this device enhances the Rayleigh backscatter signal strength at the receiving end through spatial division multiplexing, which helps to improve the signal-to-noise ratio and sensitivity of very low frequency disturbance perception and positioning signals. In addition, compared with existing synaesthesia fusion solutions, the present invention uses direct detection and intensity cross-correlation demodulation technology to simultaneously achieve high-sensitivity very low frequency disturbance perception and positioning as well as high-capacity fiber optic communications, providing an innovative solution that takes into account both very low frequency perception and positioning and large communication capacity.

[0044] Example 2

[0045] The embodiment provides a fusion device of very low frequency disturbance sensing positioning and large-capacity optical fiber communication, which comprises a signal input unit, a signal loop unit, a communication optical fiber, a sensing unit and a communication unit.

[0046] The output end of the signal input unit is connected with the input end of the signal loop unit; the output end of the signal loop unit is connected with the input end of the communication optical fiber and the sensing unit; and the output end of the communication optical fiber is connected with the communication unit.

[0047] The signal input unit is used for generating a common wavelength sensing and communication signal; the signal loop unit is used for receiving the common wavelength sensing and communication signal output by the signal input unit, and transmitting the received backscattering sensing and communication signal to the sensing unit and transmitting the forward light to the communication unit through the communication optical fiber; the sensing unit is used for positioning a very low frequency disturbance signal; and the communication unit is used for optical fiber communication.

[0048] The device comprises a signal input unit, a signal loop unit, a communication optical fiber, a sensing unit and a communication unit. The signal input unit is responsible for generating a common wavelength sensing and communication signal and outputting the signal to the signal loop unit. The signal loop unit serves as an intermediate link, receives the common wavelength sensing and communication signal from the signal input unit, and transmits the scattered light to the sensing unit and the forward light to the communication unit through the communication optical fiber. The function of the sensing unit is to detect and position a very low frequency disturbance signal, and the function of the communication unit is to perform an optical fiber communication task. Such a design enables the system to simultaneously perform very low frequency sensing detection and large-capacity data communication, and improves the comprehensive performance and efficiency of the system.

[0049] Compared with a conventional multi-core / few-mode optical fiber sensing and communication fusion technology, the device can more effectively utilize the space and spectrum resources of the optical fiber by multiplexing the communication signal and the sensing signal under the common wavelength channel, thereby improving the capacity of the communication system. Compared with an existing single-core optical fiber sensing and communication fusion scheme, the device enhances the Rayleigh backscattering signal strength at the receiving end through space division multiplexing, which helps to improve the signal-to-noise ratio and sensitivity of the very low frequency disturbance sensing and positioning signal. In addition, compared with the existing sensing and communication fusion scheme, the device can simultaneously realize high-sensitivity very low frequency disturbance sensing and positioning and large-capacity optical fiber communication by using direct detection and intensity cross-correlation demodulation technology, and provides an innovative solution of very low frequency disturbance sensing and positioning and communication capacity.

[0050] The signal input unit comprises a first laser, a first coupler, a second coupler, a chirped pulse generation module, a wavelength division demultiplexer, a first optical amplification module, a first digital subcarrier multiplexing signal generation module and N digital subcarrier multiplexing signal generation units connected in sequence.

[0051] The digital subcarrier multiplex signal generating unit comprises a narrow line width laser and a second digital subcarrier multiplex signal generating module connected in sequence.

[0052] The output end of the first laser is connected with the input end of a first coupler; the output end of the first coupler is connected with the input end of a chirp pulse generating module and a first digital subcarrier multiplex signal generating module; the output end of the chirp pulse generating module and the first digital subcarrier multiplex signal generating module is connected with the input end of a second coupler; the output end of the second coupler is connected with the input end of a wavelength division demultiplexer;

[0053] The input end of the wavelength division multiplexer is connected with the output end of the first digital subcarrier multiplex signal generating unit; the output end of the Nth digital subcarrier multiplex signal generating unit is connected with the input end of the wavelength division multiplexer; the output end of the wavelength division multiplexer is connected with the input end of a first optical amplification module;

[0054] The output end of the first optical amplification module is connected with the input end of a signal loop unit.

[0055] The communication optical fiber includes but is not limited to a single mode optical fiber, a multi-core optical fiber and a multi-core few-mode optical fiber.

[0056] When the communication optical fiber is a single mode optical fiber, the sensing unit is a first sensing unit; the signal loop unit is a first signal loop unit; the communication unit is a first communication unit; the first signal loop unit comprises a first loop unit; the first loop unit comprises a first loop, and the output end of the first loop is connected with the input end of the single mode optical fiber and the first sensing unit; the output end of the single mode optical fiber is connected with the input end of the first communication unit.

[0057] The first sensing unit comprises a second optical amplification module, a first optical filter module, a first photoelectric detection module and a first signal demodulation module connected in sequence; the output end of the first loop is connected with the input end of the second optical amplification module; the first communication unit comprises a first wavelength division demultiplexer, a first local oscillator, a first signal receiving module and a second signal demodulation module; the output end of the single mode optical fiber is connected with the input end of the first wavelength division demultiplexer; the output end of the first wavelength division demultiplexer and the first local oscillator is connected with the input end of the first signal receiving module; the output end of the first signal receiving module is connected with the input end of the second signal demodulation module.

[0058] When the communication optical fiber is a multi-core optical fiber, the sensing unit is a second sensing unit; the signal loop unit is a second signal loop unit; the communication unit is a second communication unit; the second signal loop unit comprises a second circulator unit and a first fan-in fan-out unit; the second circulator unit comprises a first circulator array composed of a plurality of second circulators connected in sequence; the output end of each second circulator of the first circulator array is connected with the input end of the first fan-in fan-out unit; the output end of each second circulator of the first circulator array is connected with the input end of the second sensing unit; the output end of the first fan-in fan-out unit is connected with the input end of the second communication unit.

[0059] The second sensing unit comprises a first optical combiner, a third optical amplification module, a second optical filter module, a second photoelectric detection module and a third signal demodulation module connected in sequence; the output end of each second circulator of the first circulator array is connected with the input end of the first optical combiner; the second communication unit comprises a second fan-in fan-out unit, a second wavelength division demultiplexer, a second local oscillator, a second signal receiving module, a fourth signal demodulation module; the output end of the multi-core optical fiber is connected with the input end of the second fan-in fan-out unit; the output end of the second fan-in fan-out unit is connected with the input end of the second wavelength division demultiplexer; the output ends of the second wavelength division demultiplexer and the second local oscillator are connected with the input end of the second signal receiving module; the output end of the second signal receiving module is connected with the input end of the fourth signal demodulation module.

[0060] When the communication optical fiber is a multi-core few-mode optical fiber, the sensing unit is a third sensing unit; the signal loop unit is a third signal loop unit; the communication unit is a third communication unit; the third signal loop unit comprises a third circulator unit, a mode multiplexer and a third fan-in fan-out unit connected in sequence; the third circulator unit comprises a second circulator array composed of a plurality of third circulators connected in sequence; the output end of each third circulator of the second circulator array is connected with the input end of the mode multiplexer; the output end of each second circulator of the second circulator array is connected with the input end of the third sensing unit; the output end of the third fan-in fan-out unit is connected with the input end of the third communication unit.

[0061] The third sensing unit comprises a second light combiner, a fourth light amplification module, a third light filter module, a third light detection module and a fifth signal demodulation module connected in sequence; the output end of each second circulator of the second circulator array is connected with the input end of the second light combiner; the third communication unit comprises a fourth fan-in fan-out unit, a mode demultiplexer, a third wavelength division demultiplexer, a third local oscillator, a third signal receiving module and a sixth signal demodulation module; the output end of the multicore few-mode fiber is connected with the input end of the fourth fan-in fan-out unit; the output end of the fourth fan-in fan-out unit is connected with the input end of the mode demultiplexer; the output end of the mode demultiplexer is connected with the input end of the third wavelength division demultiplexer; the output ends of the third wavelength division demultiplexer and the third local oscillator are connected with the input end of the third signal receiving module; the output end of the third signal receiving module is connected with the input end of the sixth signal demodulation module.

[0062] When the peak power of the co-wavelength sensing fusion signal exceeds a preset threshold, stimulated Brillouin scattering (SBS) causes very low frequency disturbance signal signal-to-noise ratio degradation; the preset threshold is:

[0063]

[0064] Wherein, A eff is the effective area of the communication optical fiber, g B is the SBS gain coefficient, L eff is the effective length of the communication optical fiber.

[0065] Embodiment 3

[0066] The embodiment provides a fusion device of very low frequency disturbance sensing positioning and large-capacity optical fiber communication, comprising a signal input unit, a signal loop unit, a communication optical fiber, a sensing unit and a communication unit; the signal input unit is a co-wavelength sensing co-wavelength sensing fusion signal generation device; the signal loop unit is a space division multiplexing signal transceiver array; the communication optical fiber is an optical fiber link; the communication unit is a communication signal receiving and demodulation device; the sensing unit is a sensing signal receiving and demodulation device; as Figure 2As shown, the common-wavelength interacuity and common-wavelength interacuity fusion signal generating device comprises an ultra-narrow linewidth laser (101), a narrow linewidth laser (102-10N), a coupler (201, 202), a chirped pulse generating module (300), a digital subcarrier multiplexing signal generating module (401-40N), a wavelength division multiplexer (500), and an optical amplifier module (601); the ultra-narrow linewidth laser (101) is used to provide a high-coherence light source; the narrow linewidth laser (102-10N) is used to provide a wavelength division multiplexed continuous optical signal; the coupler (201) is used to split the continuous light generated by the ultra-narrow linewidth laser (101) into two, one for disturbance perception positioning and the other for optical fiber communication; the chirped pulse generating module (300) is used to generate chirped pulses suitable for perception positioning; the digital subcarrier multiplexing signal generating module (401) comprises a modulator, an arbitrary waveform generator, The invention discloses a digital signal processing system for generating a digital subcarrier multiplexing communication signal with a reserved guard interval; the digital subcarrier multiplexing signal generating module (402-40N) is used to generate a digital subcarrier multiplexing communication signal without a reserved guard interval; the coupler (202) is used to multiplex the sensing detection signal into the digital subcarrier multiplexing communication signal with a reserved guard interval; the wavelength division multiplexer (500) is used to multiplex the multi-wavelength modulation signal to form a synaesthesia fusion transmission signal; the optical amplifier module (601) is used to amplify the synaesthesia fusion transmission signal; the common wavelength synaesthesia common wavelength synaesthesia fusion signal generating device outputs a common wavelength synaesthesia fusion signal with high spectrum efficiency; the system is compatible with the existing communication system expansion mechanism, and only uses communication optical cables, including but not limited to single-mode optical fiber (800), multi-core optical fiber (1800), and multi-core few-mode optical fiber (2100), to achieve the integration of very low frequency disturbance perception positioning and large-capacity optical fiber communication; Figure 7 and Figure 8 As shown, the system performance is optimized by changing the parameters of the communication signal or the sensing signal (occupied frequency band, frequency protection interval, communication signal baud rate, power ratio of the sensing signal, etc.).

[0067] like Figure 3 As shown, the device comprises a common wavelength interaceptive fusion signal generating device, a communication signal receiving and demodulating device, a sensor signal receiving and demodulating device, and a single-mode optical fiber (800). The common wavelength interaceptive fusion signal generating device, the single-mode optical fiber (800), the communication signal receiving and demodulating device, and the sensor signal receiving and demodulating device are connected in sequence to achieve the fusion of very low frequency disturbance perception positioning based on single-mode optical fiber and large-capacity optical fiber communication.

[0068] The co-wavelength sensing and communication signal generating device comprises an ultra-narrow linewidth laser (101), narrow linewidth lasers (102-10N), couplers (201, 202), a chirp pulse generating module (300), digital subcarrier multiplexing signal generating modules (401-40N), a wavelength division demultiplexer (500), and an optical amplification module (601); the co-wavelength sensing and communication signal generating device outputs a co-wavelength sensing and communication signal with high spectral efficiency;

[0069] The communication signal receiving and demodulating device comprises a wavelength division demultiplexer (900), a local laser (1000), a coherent receiving module (1100), and a communication signal demodulating module (1200); the output signal of the single-mode optical fiber (800) is demultiplexed by the wavelength division demultiplexer (900), and the multiple wavelength signals are sequentially received and demodulated;

[0070] The sensing signal receiving and demodulating device comprises an optical amplification module (602), an optical filtering module (1300), an optoelectronic detection module (1400), and a sensing signal demodulating module (1500) connected in sequence; the optical filtering module (1300) is used for filtering out communication signals and amplified spontaneous emission noise; as Figure 6 shown, a direct detection detection architecture is adopted to weaken the influence of phase noise and realize accurate positioning of very low frequency disturbance signals; an intensity cross-correlation demodulation scheme is adopted to further improve the sensing sensitivity of very low frequency disturbance;

[0071] As Figure 4 shown, the device comprises a co-wavelength sensing and communication signal generating device, a communication signal receiving and demodulating device, and a sensing signal receiving and demodulating device, and further comprises a space division multiplexing signal transceiver array and a multi-core optical fiber (1800); the co-wavelength sensing and communication signal generating device, the space division multiplexing signal transceiver array, the multi-core optical fiber (1800), the communication signal receiving and demodulating device, and the sensing signal receiving and demodulating device are connected in sequence to realize the fusion of high-sensitivity very low frequency disturbance sensing and positioning and large-capacity fiber communication based on a multi-core optical fiber.

[0072] The co-wavelength sensing and communication signal generating device comprises an ultra-narrow linewidth laser (101), narrow linewidth lasers (102-10N), couplers (201, 202), a chirp pulse generating module (300), digital subcarrier multiplexing signal generating modules (401-40N), a wavelength division demultiplexer (500), an optical amplification module (601), and a signal beam splitter (1600); the signal beam splitter is used for splitting light into multiple input signals; the system performance is optimized by changing the parameters of the communication signal or the sensing signal;

[0073] The space division multiplexing signal transceiving array includes a circulator array (700) and a fan-in fan-out (1701), and a common wavelength sensing and communication fusion signal output by a common wavelength sensing and communication fusion signal generation device is output from a port 1 of the circulator array (700) to a port 2, then enters a multi-core optical fiber (1800) through the fan-in fan-out (1701), and forward light in the multi-core optical fiber (1800) reaches a communication signal receiving and demodulation device, and Rayleigh backscattering light in the multi-core optical fiber (1800) reaches a sensing signal receiving and demodulation device through the fan-in fan-out (1701) and the port 3 of the circulator array (700);

[0074] The communication signal receiving and demodulation device includes a fan-in fan-out (1702), a wavelength division demultiplexer (900), a local laser (1000), a coherent receiving module (1100), and a communication signal demodulation module (1200), and an output signal of the fan-in fan-out (1702) is demultiplexed through the wavelength division demultiplexer (900), and the multi-wavelength signals of different cores are sequentially received and demodulated.

[0075] The sensing signal receiving and demodulation device includes sequentially connected light combiners (1900), a light amplification module (602), a light filtering module (1300), a photoelectric detection module (1400), and a sensing signal demodulation module (1500), and Rayleigh backscattering light of different cores is transmitted from the space division multiplexing signal transceiving array to the light combiner (1900), the intensity of the Rayleigh backscattering light is superimposed, and thus the signal-to-noise ratio and sensitivity of the disturbance sensing and positioning signal are improved.

[0076] As shown in Figure 5 The device includes a common wavelength sensing and communication fusion signal generation device, a communication signal receiving and demodulation device, and a sensing signal receiving and demodulation device, further includes a space division multiplexing signal transceiving array and a multi-core few-mode optical fiber (2100), and the common wavelength sensing and communication fusion signal generation device, the space division multiplexing signal transceiving array, the multi-core few-mode optical fiber (2100), the communication signal receiving and demodulation device, and the sensing signal receiving and demodulation device are sequentially connected, and the fusion of high-sensitivity very low frequency disturbance sensing and positioning and large-capacity optical fiber communication based on the multi-core few-mode optical fiber is realized.

[0077] The common wavelength sensing and communication fusion signal generation device includes an ultra-narrow linewidth laser (101-10K), a narrow linewidth laser (10K+1-10N), a coupler (200), a chirp pulse generation module (300), a digital subcarrier multiplexing signal generation module (401-40N), a wavelength division demultiplexer (500), a light amplification module (601), and a signal beam splitter (1600), and the system performance is optimized by changing the parameters of the communication signal or the sensing signal.

[0078] The space division multiplexing signal transceiving array includes a circulator array (700), a mode multiplexer (2001), and a fan-in fan-out (1701). The multi-wavelength sensing signal output by the common wavelength sensing signal generation device is output from port 1 of the circulator array (700) to port 2, then enters the multi-core few-mode fiber (2100) through the mode multiplexer (2001) and the fan-in fan-out (1701), the forward light in the multi-core few-mode fiber (2100) reaches the communication signal receiving and demodulation device, and the Rayleigh backscattering light in the multi-core few-mode fiber (2100) reaches the sensing signal receiving and demodulation device through port 3 of the circulator array (700) and the mode multiplexer (2001).

[0079] The communication signal receiving and demodulation device includes a fan-in fan-out (1702), a mode demultiplexer (2002), a wavelength division demultiplexer (900), a local laser (1000), a coherent receiving module (1100), and a communication signal demodulation module (1200). The output signal of the mode demultiplexer (2002) is demultiplexed by the wavelength division demultiplexer (900), and the multi-wavelength signals of different cores and different modes are sequentially received and demodulated.

[0080] The sensing signal receiving and demodulation device includes a light combiner (1900), a light amplification module (602), a light filtering module (1300), a photoelectric detection module (1400), and a sensing signal demodulation module (1500) connected in sequence. The Rayleigh backscattering light of different cores and different modes is transmitted from the signal space division transceiving array to the light combiner (1900), realizing the intensity superposition of the Rayleigh backscattering light in the optical domain, thereby improving the signal-to-noise ratio and sensitivity of the disturbance sensing positioning signal. The scheme is also applicable to multi-wavelength sensing signals, and the sensitivity is improved by superimposing Rayleigh backscattering light of different wavelengths.

[0081] The external disturbance signal locally changes the length and refractive index of the communication optical fiber. When a direct detection mode based on a chirped pulse is used, the change in refractive index will cause a change in frequency. Due to the time-frequency mapping relationship of the chirped pulse, the external disturbance signal will cause a local time delay in the intensity curve, and the time delay amount is linearly related to the external disturbance amount. The external disturbance signal can be quantitatively measured by intensity cross-correlation demodulation, and the disturbance positioning is realized by the time-of-flight method. The relationship between the disturbance amount and the local time delay amount is:

[0082]

[0083] where Δn g is the local refractive index change caused by the disturbance signal, n g is the refractive index of the optical fiber, Δv is the frequency shift amount caused by the disturbance signal, v0 is the center frequency of the probe pulse, δv p is the sweep bandwidth of the chirped pulse, and τ pis the duration of the chirped pulse, At is the local time delay of the intensity curve caused by the perturbation signal, and Δε is the strain.

[0084] (1) Intensity cross-correlation demodulation algorithm 1:

[0085] T1(t) = max(correlation [E i (t-τ corr ,t+τ corr ), E i+1 (t-τ corr ,t+τ corro )])#(2)

[0086] where T1(t) is the local time delay obtained by the intensity cross-correlation demodulation algorithm 1; correlation is the cross-correlation function; E i is the i-th Rayleigh scattering intensity curve, i = 1:n-1, and n is the number of intensity curves; t is the sampling time; and τ corr is the cross-correlation time window. The local cross-correlation time delay of two consecutive intensity curves can be obtained by algorithm 1, and the values obtained by the cross-correlation of [E1, E2], [E2, E3], …, [E n-1 , E n ] can measure the change of strain with time. When the local time delay is small, the time delay estimated by two consecutive intensity curves also has errors due to quantization errors, resulting in poor demodulation effect.

[0087] (2) Intensity cross-correlation demodulation algorithm 2:

[0088] T2(t) = max(correlation [E1(t-τ corr ,t+τ corr ), E i+1 (t-τ corr ,t+τ corr )])#(3)

[0089] where T2(t) is the local time delay obtained by the intensity cross-correlation demodulation algorithm 2; correlation is the cross-correlation function; E i is the i-th Rayleigh scattering intensity curve, i = 1:n-1, and n is the number of intensity curves; t is the sampling time; and τ corr is the cross-correlation time window. The local cross-correlation time delay of the first and i-th intensity curves can be obtained by algorithm 2, and the values obtained by the cross-correlation of [E1, E2], [E1, E3], …, [E1, E n ] can measure the change of strain with time. Compared with algorithm 1, when the local time delay is small, the time delay error estimated by the first and i-th intensity curves is smaller due to smaller quantization error, resulting in better demodulation effect.

[0090] (3) Improved intensity cross-correlation demodulation algorithm 3:

[0091] T3(t) = max(correlation[E i (t-τ corr ,t+τ corr ), E k (t-τ corr ,t+τ corr )])#(4)

[0092] where T3(t) is the local time delay obtained by the intensity cross-correlation demodulation algorithm 3; correlation is the cross-correlation function; E i is the i-th Rayleigh scattering intensity curve, i = 1:n-1, k = (i+1):n, n is the number of intensity curves; t is the sampling time; τ corr is the cross-correlation time window. The difference from algorithm 2 is that: algorithm 2 fixes the first curve as the reference curve, and the remaining curves are cross-correlated with the first curve; while algorithm 3 reduces the error by changing the reference curve and estimating multiple times. In the first stage, the first curve is fixed as the reference curve, and the second to the nth curve is cross-correlated with it; in the second stage, the second curve is fixed as the reference curve, and the third to the nth curve is cross-correlated with it; …, in the last stage, the n-1th curve is fixed as the reference curve, and the n-1th curve is cross-correlated with the n-th curve. Compared with algorithm 2, the local time delay of the first curve and the remaining curves in algorithm 3 is estimated multiple times, and the estimation error can be reduced by averaging, thereby improving the demodulation effect.

[0093] Generally, the Rayleigh backscattering signal power is weak, resulting in a low signal-to-noise ratio of the DAS system and limiting the spatial resolution of distributed sensing. The Rayleigh backscattering signal strength can be increased by increasing the pulse duration, but the increase in pulse duration will result in poorer spatial resolution because the pulse duration is inversely proportional to the spatial resolution. The Rayleigh backscattering signal strength can also be increased by increasing the peak power of the pulse, but the peak power is limited by the nonlinear effects of the optical fiber. When the peak power exceeds a threshold value, stimulated Brillouin scattering (SBS) will cause the signal-to-noise ratio of the very low frequency disturbance signal to deteriorate. The estimation formula of the SBS threshold is as follows:

[0094]

[0095] where A eff is the effective area of the optical fiber, g B is the SBS gain coefficient, L eff is the effective length of the optical fiber, α = 0.2 dB / km, and w is the mode field radius.

[0096] The present application breaks the limitation of the peak power of the single-core DAS system being subject to the nonlinear threshold of the optical fiber by using space division multiplexing to detect Rayleigh backscattering light of each core / mode, increases the intensity of the Rayleigh backscattering signal at the receiving end, thereby improving the signal-to-noise ratio, and further improving the sensitivity. The noise floor of the perturbation amplitude spectrum density (ASD) is

[0097]

[0098] where SNR is the signal-to-noise ratio, v0 is the center frequency of the laser detection pulse, δv is the sweep bandwidth of the chirped pulse, τ is the cross-correlation time window, and f is the pulse repetition frequency (i.e., the perturbation sampling rate). As can be seen from equation 6, the greater the signal-to-noise ratio of the signal, the smaller the noise floor, thus improving the sensitivity of the DAS system. electrical p corr s,ac As can be seen from equation 6, the greater the signal-to-noise ratio of the signal, the smaller the noise floor, thus improving the sensitivity of the DAS system.

[0099] Compared with the conventional multi-core / few-mode optical fiber sensing and communication fusion scheme that uses different cores / modes to respectively transmit the communication signal and the sensing signal, the present embodiment can fully utilize the spatial resource and the spectral resource of the optical fiber and improve the communication system capacity by multiplexing the communication signal and the sensing signal under the same wavelength channel. Compared with the existing single-core optical fiber sensing and communication fusion scheme, the present embodiment increases the intensity of the Rayleigh backscattering signal at the receiving end by using space division multiplexing, thereby improving the signal-to-noise ratio and the sensitivity of the very low frequency perturbation sensing and positioning signal. Compared with the existing sensing and communication fusion scheme, the present embodiment uses direct detection and intensity cross-correlation demodulation to realize very low frequency perturbation sensing and positioning, and can simultaneously realize high-sensitivity very low frequency perturbation sensing and positioning and large-capacity optical fiber communication.

[0100] The same or similar reference signs correspond to the same or similar components;

[0101] The terms used to describe the positional relationship in the drawings are only used for exemplary illustration and should not be understood as a limitation on the patent; obviously, the above embodiments of the present application are only examples for clearly illustrating the present application, and are not a limitation on the embodiments of the present application. Based on the above description, those skilled in the art can make other different forms of changes or variations. Here, it is not necessary or possible to exhaust all the embodiments. Any modification, equivalent replacement and improvement made within the spirit and principles of the present application should be included in the protection scope of the claims of the present application.​​​

Claims

1. A device integrating very low frequency disturbance sensing and positioning with high-capacity optical fiber communication, characterized in that: It includes a signal input unit, a signal ring unit, a communication optical fiber, a sensing unit and a communication unit; The output end of the signal input unit is connected to the input end of the signal ring unit; the output end of the signal ring unit is connected to both the communication optical fiber and the input end of the sensing unit; the output end of the communication optical fiber is connected to the communication unit; The signal input unit is used to generate a common-wavelength synaesthesia fusion signal; the signal ring unit is used to receive the common-wavelength synaesthesia fusion signal output by the signal input unit, and transmit the backscattered synaesthesia fusion signal to the sensing unit and transmit the forward light to the communication unit through the communication optical fiber; the sensing unit is used to locate the very low frequency disturbance signal; and the communication unit is used for optical fiber communication. The signal input unit includes a first laser, a first coupler, a second coupler, a chirped pulse generating module, a wavelength division multiplexer, a first optical amplification module, a first digital subcarrier multiplexing signal generating module and N digital subcarrier multiplexing signal generating units connected in sequence; The digital subcarrier multiplexed signal generating unit comprises a narrow linewidth laser and a second digital subcarrier multiplexed signal generating module connected in sequence; The output end of the first laser is connected to the input end of the first coupler; the output end of the first coupler is connected to the input ends of the chirped pulse generating module and the first digital subcarrier multiplexing signal generating module; the output ends of the chirped pulse generating module and the first digital subcarrier multiplexing signal generating module are both connected to the input end of the second coupler; the output end of the second coupler is connected to the input end of the wavelength division multiplexer; The input end of the wavelength division multiplexer is connected to the output end of the first digital subcarrier multiplexing signal generating unit; the output end of the Nth digital subcarrier multiplexing signal generating unit is connected to the input end of the wavelength division multiplexer; the output end of the wavelength division multiplexer is connected to the input end of the first optical amplifier module; the signal input unit is used to generate a common wavelength interawareness fusion signal, which is compatible with the existing expansion mechanism; The output end of the first optical amplification module is connected to the input end of the signal ring unit.

2. The fusion device of very low frequency disturbance sensing and positioning and large-capacity optical fiber communication according to claim 1 is characterized in that: The communication optical fiber includes but is not limited to single-mode optical fiber, multi-core optical fiber and multi-core few-mode optical fiber.

3. The fusion device of very low frequency disturbance sensing and positioning and large-capacity optical fiber communication according to claim 2 is characterized in that: When the communication optical fiber is a single-mode optical fiber, the sensing unit is a first sensing unit; the signal ring unit is a first signal ring unit; the communication unit is a first communication unit; the first signal ring unit includes a first circulator unit; the first circulator unit includes a first circulator, the output end of the first circulator is connected to the single-mode optical fiber and the input end of the first sensing unit; the output end of the single-mode optical fiber is connected to the input end of the first communication unit.

4. The fusion device of very low frequency disturbance sensing and positioning and large-capacity optical fiber communication according to claim 3 is characterized in that: The first sensing unit includes a second optical amplification module, a first optical filter module, a first photoelectric detection module, and a first signal demodulation module connected in sequence; the output end of the first circulator is connected to the input end of the second optical amplification module; the first sensing unit uses direct detection and cross-correlation demodulation to achieve very low frequency perception; The first communication unit includes a first wavelength division multiplexer, a first local oscillator laser, a first signal receiving module and a second signal demodulation module; the output end of the single-mode optical fiber is connected to the input end of the first wavelength division multiplexer; the output ends of the first wavelength division multiplexer and the first local oscillator laser are both connected to the input end of the first signal receiving module; the output end of the first signal receiving module is connected to the input end of the second signal demodulation module; the first communication unit is used to receive and demodulate the multi-wavelength signals in sequence.

5. The device for integrating very low frequency disturbance sensing and positioning with large-capacity optical fiber communication according to claim 2, characterized in that: When the communication optical fiber is a multi-core optical fiber, the sensing unit is a second sensing unit; the signal ring unit is a second signal ring unit; the communication unit is a second communication unit; the second signal ring unit includes a second circulator unit and a first fan-in fan-out unit; the second circulator unit includes a first circulator array composed of a number of second circulators connected in sequence; the output end of each second circulator in the first circulator array is connected to the input end of the first fan-in fan-out unit; the output end of each second circulator in the first circulator array is connected to the input end of the second sensing unit; the output end of the first fan-in fan-out unit is connected to the input end of the second communication unit.

6. The device for integrating very low frequency disturbance sensing and positioning with large-capacity optical fiber communication according to claim 5, characterized in that: The second sensing unit includes a first optical combiner, a third optical amplification module, a second optical filtering module, a second photoelectric detection module, and a third signal demodulation module connected in sequence; the output end of each second circulator in the first circulator array is connected to the input end of the first optical combiner; the second sensing unit uses direct detection and cross-correlation demodulation to achieve very low frequency perception; The second communication unit includes a second fan-in fan-out unit, a second wavelength division multiplexer, a second local oscillator laser, a second signal receiving module, and a fourth signal demodulation module; the output end of the multi-core optical fiber is connected to the input end of the second fan-in fan-out unit; the output end of the second fan-in fan-out unit is connected to the input end of the second wavelength division multiplexer; the output ends of the second wavelength division multiplexer and the second local oscillator laser are connected to the input end of the second signal receiving module; The output end of the second signal receiving module is connected to the input end of the fourth signal demodulation module; the second communication unit is used to sequentially receive and demodulate multi-wavelength signals of different fiber cores.

7. The device for integrating very low frequency disturbance sensing and positioning with large-capacity optical fiber communication according to claim 2, characterized in that: When the communication optical fiber is a multi-core few-mode optical fiber, the sensing unit is a third sensing unit; the signal ring unit is a third signal ring unit; the communication unit is a third communication unit; the third signal ring unit includes a third circulator unit, a mode multiplexer and a third fan-in and fan-out unit connected in sequence; the third circulator unit includes a second circulator array composed of several third circulators connected in sequence; the output end of each third circulator of the second circulator array is connected to the input end of the mode multiplexer; the output end of each second circulator of the second circulator array is connected to the input end of the third sensing unit; the output end of the third fan-in and fan-out unit is connected to the input end of the third communication unit.

8. The device for integrating very low frequency disturbance sensing and positioning with large-capacity optical fiber communication according to claim 7, characterized in that: The third sensing unit includes a second optical combiner, a fourth optical amplification module, a third optical filtering module, a third photoelectric detection module, and a fifth signal demodulation module connected in sequence; the output end of each second circulator in the second circulator array is connected to the input end of the second optical combiner; the third sensing unit uses direct detection and cross-correlation demodulation to achieve very low frequency perception; The third communication unit includes a fourth fan-in and fan-out unit, a mode demultiplexer, a third wavelength division multiplexer, a third local oscillator laser, a third signal receiving module and a sixth signal demodulation module; the output end of the multi-core few-mode optical fiber is connected to the input end of the fourth fan-in and fan-out unit; the output end of the fourth fan-in and fan-out unit is connected to the input end of the mode demultiplexer; the output end of the mode demultiplexer is connected to the input end of the third wavelength division multiplexer; the output ends of the third wavelength division multiplexer and the third local oscillator laser are both connected to the input end of the third signal receiving module; the output end of the third signal receiving module is connected to the input end of the sixth signal demodulation module; the third communication unit is used to sequentially receive and demodulate multi-wavelength signals of different fiber cores and different modes.

9. The device for integrating very low frequency disturbance sensing and positioning with large-capacity optical fiber communication according to claim 1, characterized in that: When the peak power of the common-wavelength synaesthesia fusion signal exceeds a preset threshold, stimulated Brillouin scattering will cause the signal-to-noise ratio of the very low frequency disturbance signal to deteriorate; the preset threshold is: in, is the effective area of ​​the communication optical fiber, is the SBS gain coefficient, is the effective length of the communication optical fiber.

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