Communication and sensing integrated device based on seven-core optical fiber interferometer and application method therefor

Abstract

The present invention relates to the field of communication and sensing, and specifically to a communication and sensing integrated device based on a seven-core optical fiber interferometer and an application method therefor. The application method comprises: a first beam splitter splitting, into reference light and signal light, a light source emitted by a narrow linewidth laser; performing modulation by means of a first coherent optical transmitter and a second coherent optical transmitter; amplifying the light by means of a first amplifier and a second amplifier, and then enabling the light to pass through a multi-core optical fiber from a fan-in end, and to output from a fan-out end; performing beam splitting by means of a second beam splitter and a third beam splitter, and performing demodulation by means of a first coherent receiver and a second coherent receiver; and finally, a phase-locked loop performing interference elimination on preliminarily-demodulated reference light and preliminarily-demodulated signal light to obtain finally-demodulated reference light and finally-demodulated signal light. The present invention uses a phase-locked loop to further eliminate disturbance noise of reference light and signal light. Therefore, noise interference is eliminated in continuous low-frequency detection, thereby improving the communication and sensing effect.

Description

Seven-core fiber interferometer communication sensing integrated device and application method thereof TECHNICAL FIELD

[0001] The present application relates to the field of communication sensing, and more particularly, to a seven-core fiber interferometer communication sensing integrated device and application method thereof. BACKGROUND

[0002] In recent years, there has been growing interest in supporting simultaneous communication and sensing capabilities in fiber networks. If sensing technology can be loaded in the fiber simultaneously, the fiber network can monitor the external environment in a large coverage range, which is conducive to the early detection of fiber communication faults, and the development of public safety and smart city systems. In addition, the optical communication infrastructure can provide convenient power supply for fiber transmission and fast data transmission. Previous solutions mainly focus on instantaneous and high-frequency vibration detection, but continuous low-frequency detection is also very important for various applications. In low-frequency, through fiber interferometry, laser phase noise and slow and random phase perturbations will be converted into noise, which will deteriorate when performing symmetric fiber interferometry, thereby affecting the final communication sensing effect.

[0003] SUMMARY

[0004] The purpose of the present application is to disclose a seven-core fiber interferometer communication sensing integrated device and application method thereof suitable for continuous low-frequency detection and having better communication sensing effect.

[0005] In order to achieve the above-mentioned purpose, the present application provides a seven-core fiber interferometer communication sensing integrated device, comprising: narrow linewidth laser, first beam splitter, first coherent transmitter, second coherent transmitter, first optical amplifier, second optical amplifier, fan-in end, fan-out end, multi-core fiber, second beam splitter, third beam splitter, first coherent receiver, second coherent receiver and phase-locked loop.

[0006] The phase-locked loop comprises an acousto-optic modulator, a piezoelectric ceramic fiber stretcher, a low-pass filter, a coupler, a balanced photodetector, a frequency mixer and a band-pass filter.

[0007] The narrow linewidth laser is connected with the first coherent transmitter and the second coherent transmitter through the first beam splitter, the first coherent transmitter is connected with a fan-in end through a first optical amplifier, the first coherent transmitter is connected with a fan-in end through a second optical amplifier, the fan-in end is connected with the fan-out end through the multi-core optical fiber, the fan-out end is connected with the first coherent receiver and the acousto-optic modulator through the second beam splitter, the fan-out end is connected with the second coherent receiver and the piezoelectric ceramic fiber stretcher through the third beam splitter, the acousto-optic modulator and the piezoelectric ceramic fiber stretcher are connected with the balanced photodetector through the coupler, the balanced photodetector is connected with the mixer through the band-pass filter, the piezoelectric ceramic fiber stretcher is connected with the mixer through the mixer, and the acousto-optic modulator is connected with the mixer.

[0008] In addition, the application provides an application method of the seven-core fiber interferometer communication and sensing integrated device, which comprises the following steps:

[0009] S1: the first beam splitter divides the light source emitted by the narrow linewidth laser into reference light and signal light;

[0010] S2: the reference light is modulated by the first coherent light transmitter to obtain modulated reference light, and the signal light is modulated by the second coherent transmitter to obtain modulated signal light;

[0011] S3: the modulated reference light is amplified by the first amplifier to obtain amplified modulated reference light, and the modulated signal light is amplified by the second amplifier to obtain amplified modulated signal light,

[0012] S4: the amplified modulated reference light and the amplified modulated signal light are output from the fan-in end through the multi-core optical fiber to obtain output reference light and output signal light;

[0013] S5: the output reference light is divided by the second beam splitter to obtain first output reference light and second output reference light, and the output signal light is divided by the third beam splitter to obtain first output signal light and second output signal light,

[0014] S6: the first output reference light is demodulated by the first coherent receiver to obtain preliminary demodulated reference light, and the first output signal light is demodulated by the second coherent receiver to obtain preliminary demodulated signal light;

[0015] S7: the second output reference light and the second output signal light are subjected to interference cancellation on the preliminary demodulated reference light and the preliminary demodulated signal light through a phase-locked loop to obtain final demodulated reference light and final demodulated signal light.

[0016] Further, step S2 includes: modulating the reference light with a dual-polarization QAM signal through a first coherent optical transmitter to obtain modulated reference light, and modulating the signal light with a dual-polarization QAM signal through a second coherent transmitter to obtain modulated signal light.

[0017] Further, in step S2, a DC component with a power 34 dB lower than the reference light is added when the reference light passes through the first coherent optical transmitter, and a DC component with a power 34 dB lower than the signal light is added when the signal light passes through the second coherent optical transmitter.

[0018] Further, step S6 includes: first, eliminating the DC component through frequency offset compensation and DC removal algorithm; then, demodulating the first output reference light through a first coherent receiver to obtain preliminary demodulated reference light; and demodulating the first output signal light through a second coherent receiver to obtain preliminary demodulated signal light.

[0019] Further, in step S4, the amplified and modulated reference light is passed from the fan-in end through one core of the multi-core optical fiber and output from the fan-out end to obtain the output reference light, and the amplified and modulated signal light is passed from the fan-in end through any core of the multi-core optical fiber other than the first core and output from the fan-out end to obtain the output signal light.

[0020] Further, in step S7, the second output reference light is frequency-shifted by passing it through a 40MHz acousto-optic modulator before entering the phase-locked loop.

[0021] Furthermore, in step S7, the phase-locked loop consists of a balanced photodetector, a loop filter, and an optical fiber stretcher. The balanced photodetector performs coherent detection on the mixed second output reference light and the second output signal light to complete the conversion of optical signal to electrical signal and eliminate common-mode noise.

[0022] Further, in step S7, the following steps are included: filtering out the 40MHz signal through a bandpass filter; the 40MHz electrical signal is down-converted to a base frequency signal after entering the mixer, thereby detecting phase information; real-time compensation of the disturbed phase information is performed through a loop filter and an optical fiber stretcher; the base frequency electrical signal forms an error signal after passing through the loop filter and is then fed back to the optical fiber stretcher in the control link to compensate for the phase information.

[0023] Furthermore, this includes: the photocurrent without coherent detection is:

[0024] Where r is the response of BPD, P s and P r It is the carrier power of the signal light and the reference light, while ω IF =ω s -ω r φ is the frequency difference between the signal light and the local oscillator light.e = phi s (t) - phi r (t) is the phase difference of signal light and reference light, that is, the signal to be demodulated, phi c is the beat frequency noise caused by the laser phase noise and the laser relative disturbance noise introduced by the environmental disturbance changes such as temperature change and vibration during the optical fiber transmission, which is the main noise source of the interference demodulator, the noise is mainly in the low frequency region, which will seriously affect the demodulation signal, phi n (t) is the phase noise introduced by the modulated communication signal, since the bandwidth of the communication signal is much higher than that of the vibration signal, phi n (t) is also a wide bandwidth signal, and the power in the local frequency band is much lower than that of the carrier signal;

[0025] After the mixer and low-pass filter processing, only the last three terms of the phase term in the sinusoidal signal are left: phi = phi e (t) + phi' c (t) + phi' n (t), when passing through the phase-locked loop, the error signal of the loop filter is converted into a strong voltage control PZT, which compensates phi' c (t), at this time, i PD (t) changes to:

[0026] phi PZT (t) is the phase change introduced by the PZT, by setting appropriate filter parameters, phi PZT (t) can quickly track the phase noise phi' c (t) and suppress it, realize real-time dynamic compensation, and ensure stable interference and coherent detection.

[0027] Compared with the prior art, the beneficial effects of the technical scheme of the present application are:

[0028] The application adopts multi-core optical fiber as a transmission medium. On one hand, the application utilizes the space division multiplexing characteristics to make the reference light and the signal light transmit synchronously in the same optical fiber. The synchronous transmission ensures that the two lights experience basically the same path in the transmission process. Therefore, the noise and the jitter caused by the environmental disturbance are converted from the differential mode noise to the common mode noise, and the common mode noise is easier to suppress. Therefore, the multi-core optical fiber, as the transmission channel of the reference light and the signal light, also plays a role in preliminarily suppressing the relative disturbance noise of the two lights. On the other hand, the multi-core optical fiber can increase the communication channel. Since the inter-core crosstalk of the weakly coupled optical fiber is low, the transmission of the optical communication information between different cores has almost no influence, thereby improving the transmission capacity. Meanwhile, the multi-core optical fiber is compatible with the existing single-mode optical fiber communication system, and is one of the solutions for the next generation of large-capacity space division multiplexing optical fiber communication. In addition, the application adopts a phase-locked loop to further eliminate the disturbance noise of the reference light and the signal light. Therefore, the noise interference is eliminated in the continuous low-frequency detection, and the communication sensing effect is improved. BRIEF DESCRIPTION OF DRAWINGS

[0029] Fig. 1 is a structure schematic diagram of the communication and sensing integrated device based on the seven-core optical fiber interferometer according to the embodiment one;

[0030] Fig. 2 is a flow chart of the application method of the communication and sensing integrated device based on the seven-core optical fiber interferometer according to the embodiment two;

[0031] Fig. 3 is a comparison diagram of the signal output when the phase-locked loop is opened and closed when a 50Hz sine wave vibration is applied from the outside according to the embodiment three;

[0032] Fig. 4 is a frequency spectrum diagram of the output signal when the phase-locked loop is opened and closed when a 50Hz sine wave vibration is applied from the outside according to the embodiment three;

[0033] Fig. 5 is a recovery diagram of the vibration signal with different frequencies according to the embodiment three;

[0034] Fig. 6 is a constellation diagram and a bit error rate diagram of the signal recovered after demodulation of the signal received at the coherent receiving end according to the embodiment three;

[0035] In the figure, 1 is a narrow line width laser, 2 is a first beam splitter, 3 is a first coherent transmitter, 4 is a second coherent transmitter, 5 is a first optical amplifier, 6 is a second optical amplifier, 7 is a fan-in end, 8 is a fan-out end, 9 is a multi-core optical fiber, 10 is a second beam splitter, 11 is a third beam splitter, 12 is a first coherent receiver, 13 is a second coherent receiver, 14 is a phase-locked loop, 15 is an acousto-optic modulator, 16 is a piezoelectric ceramic fiber stretcher, 17 is a low-pass filter, 18 is a coupler, 19 is a balanced photodetector, 20 is a mixer, and 21 is a band-pass filter; DETAILED DESCRIPTION

[0036] The accompanying drawings are only used for illustrative purposes and cannot be understood as a limitation of the patent;

[0037] The technical solutions of the present application will be further described below in combination with the drawings and examples.

[0038] Example one:

[0039] The present embodiment provides a seven-core fiber interferometer communication and sensing integrated device as shown in FIG. 1, which comprises a narrow linewidth laser 1, a first beam splitter 2, a first coherent transmitter 3, a second coherent transmitter 4, a first optical amplifier 5, a second optical amplifier 6, a fan-in end 7, a fan-out end 8, a multi-core fiber 9, a second beam splitter 10, a third beam splitter 11, a first coherent receiver 12, a second coherent receiver 13 and a phase-locked loop 14.

[0040] The phase-locked loop 14 comprises an acousto-optic modulator 15, a piezoelectric ceramic fiber stretcher 16, a low-pass filter 17, a coupler 18, a balanced photodetector 19, a frequency mixer 20 and a band-pass filter 21.

[0041] Wherein the narrow linewidth laser 1 is connected with the first coherent transmitter 3 and the second coherent transmitter 4 through the first beam splitter 2 respectively, the first coherent transmitter 3 is connected with the fan-in end 7 through the first optical amplifier 5, the first coherent transmitter 3 is connected with the fan-in end 7 through the second optical amplifier 6, the fan-in end 7 is connected with the fan-out end 8 through the multi-core fiber 9, the fan-out end 8 is connected with the first coherent receiver 12 and the acousto-optic modulator 15 through the second beam splitter 10 respectively, the fan-out end 8 is connected with the second coherent receiver 13 and the piezoelectric ceramic fiber stretcher 16 through the third beam splitter 11 respectively, the acousto-optic modulator 15 and the piezoelectric ceramic fiber stretcher 16 are connected with the balanced photodetector 19 through the coupler 18, the balanced photodetector 19 is connected with the frequency mixer 20 through the band-pass filter 21, the piezoelectric ceramic fiber stretcher 16 is connected with the frequency mixer 20 through the frequency mixer 20, and the acousto-optic modulator 15 is connected with the frequency mixer 20.

[0042] The embodiment adopts the multi-core optical fiber 9 as the transmission medium. On the one hand, the space division multiplexing characteristics are utilized to enable the reference light and the signal light to be transmitted synchronously in the same optical fiber. The synchronous transmission ensures that the two beams of light experience substantially the same path during the transmission. Therefore, the noise and the jitter caused by the environmental disturbance are converted from the differential mode noise to the common mode noise. The common mode noise is easier to suppress, and therefore the multi-core optical fiber 9, as the transmission channel of the reference light and the signal light, also plays a role in preliminarily suppressing the relative disturbance noise of the two beams of light. On the other hand, the multi-core optical fiber 9 can increase the communication channel. Since the inter-core crosstalk of the weakly coupled optical fiber is low, the optical communication information has little influence when being transmitted between different cores, thereby improving the transmission capacity. Meanwhile, the multi-core optical fiber 9 is compatible with the existing single-mode optical fiber communication system, and is one of the solutions for the next-generation large-capacity space division multiplexing optical fiber communication. In addition, the embodiment adopts the phase-locked loop 14 to further eliminate the disturbance noise of the reference light and the signal light. Therefore, the noise interference is eliminated in the continuous low-frequency detection, and the communication sensing effect is improved.

[0043] Embodiment two:

[0044] The embodiment provides an application method of the seven-core optical fiber interferometer communication and sensing integrated device as shown in FIG. 2. The seven-core optical fiber interferometer communication and sensing integrated device is applied, and includes the following steps.

[0045] S1: The first beam splitter divides the light source emitted by the narrow linewidth laser into reference light and signal light;

[0046] S2: The reference light passes through the first coherent light transmitter to obtain modulated reference light, and the signal light passes through the second coherent transmitter to obtain modulated signal light;

[0047] S3: The modulated reference light passes through the first amplifier to obtain amplified modulated reference light, and the modulated signal light passes through the second amplifier to obtain amplified modulated signal light,

[0048] S4: The amplified modulated reference light and the amplified modulated signal light are output from the fan-in end through the multi-core optical fiber, and the output reference light and the output signal light are output from the fan-out end;

[0049] S5: The output reference light passes through the second beam splitter to obtain first output reference light and second output reference light, and the output signal light passes through the third beam splitter to obtain first output signal light and second output signal light,

[0050] S6: The first output reference light is demodulated by the first coherent receiver to obtain preliminary demodulated reference light, and the first output signal light is demodulated by the second coherent receiver to obtain preliminary demodulated signal light;

[0051] S7: The second output reference light and the second output signal light interfere with the preliminary demodulation reference light and the preliminary demodulation signal light through a phase-locked loop to obtain the final demodulation reference light and the final demodulation signal light.

[0052] In the embodiment, the multi-core optical fiber is used as a transmission medium. On the one hand, the spatial division multiplexing characteristics are used to synchronize the transmission of the reference light and the signal light in the same optical fiber, and the synchronization transmission ensures that the two lights experience substantially the same path during the transmission. Therefore, the noise and the jitter caused by the environmental disturbance are converted from the differential mode noise to the common mode noise, and the common mode noise is easier to suppress, so that the multi-core optical fiber, as the transmission channel of the reference light and the signal light, also plays a role in preliminarily suppressing the relative disturbance noise of the two lights. On the other hand, the multi-core optical fiber can increase the communication channel, and the inter-core crosstalk of the weakly coupled optical fiber is low, so that the optical communication information has little influence when being transmitted between different cores, thereby improving the transmission capacity. Meanwhile, the multi-core optical fiber is compatible with the existing single-mode optical fiber communication system, and is one of the solutions for the next-generation large-capacity spatial division multiplexing optical fiber communication. In addition, the phase-locked loop is used in the embodiment to further eliminate the disturbance noise of the reference light and the signal light. Therefore, the noise interference is eliminated in the continuous low-frequency detection, and the communication sensing effect is improved.

[0053] Embodiment three

[0054] The embodiment further discloses the embodiment one.

[0055] In step S2, the reference light is modulated by the first coherent light transmitter to obtain modulated reference light, and the signal light is modulated by the second coherent light transmitter to obtain modulated signal light.

[0056] In step S2, a direct current component with a power 34 dB lower than that of the reference light is added to the reference light when the reference light passes through the first coherent light transmitter, and a direct current component with a power 34 dB lower than that of the signal light is added to the signal light when the signal light passes through the second coherent light transmitter.

[0057] In step S6, the direct current components are eliminated through the frequency offset compensation and the direct current elimination algorithm, then the first output reference light is demodulated by the first coherent receiver to obtain the preliminary demodulation reference light, and the first output signal light is demodulated by the second coherent receiver to obtain the preliminary demodulation signal light.

[0058] In step S4, the amplified modulated reference light is output from the fan-out end through one core of the multi-core optical fiber, to obtain the output reference light, and the amplified modulated signal light is output from the fan-out end through any core of the multi-core optical fiber except the one core, to obtain the output signal light.

[0059] In step S7, the second output reference light is frequency shifted by a 40MHz acousto-optic modulator and then enters a phase-locked loop.

[0060] In step S7, the phase-locked loop is composed of a balanced photodetector, a loop filter and a fiber stretcher. The balanced photodetector coherently detects the mixed second output reference light and the second output signal light, converts the optical signal into an electrical signal and eliminates common-mode noise.

[0061] In step S7, the 40MHz signal is filtered out by a band-pass filter, and the 40MHz electrical signal is down-converted to a base frequency signal in a frequency mixer, so that the phase information is detected. The loop filter and the fiber stretcher compensate for the disturbed phase information in real time. The base frequency electrical signal forms an error signal after passing through the loop filter, and then the error signal is fed back to the fiber stretcher in the control link to compensate for the phase information.

[0062] The photocurrent without coherent detection is:

[0063] where r is the responsivity of the BPD, P s and P r are the carrier powers of the signal light and the reference light, and ω IF = ω s - ω r is the frequency difference between the signal light and the local light, φ e = φ s (t) - φ r (t) is the phase difference between the signal light and the reference light, i.e. the signal to be demodulated, φ c is the beat frequency noise caused by the phase noise of the laser and the relative disturbance noise of the laser caused by environmental disturbances such as temperature changes and vibrations during fiber transmission. This is the main noise source of the interference demodulator. This noise mainly exists in the low frequency region and will seriously affect the demodulation signal. φ n (t) is the phase noise introduced by the modulated communication signal. Since the bandwidth of the communication signal is much higher than that of the vibration signal, φ n (t) is also a wide bandwidth signal, and the power in the local frequency band is much lower than that of the carrier signal.

[0064] After passing through the frequency mixer and the low-pass filter, only the last three terms of the phase term in the sinusoidal signal are left: φ = φ e (t) + φ′ c (t) + φ′ n (t). When passing through the phase-locked loop, the error signal of the loop filter is converted into a strong voltage control PZT to compensate for φ′ c (t). At this time, i PD (t) changes to:

[0065] φ PZT (t) is the phase change introduced by PZT, by setting appropriate filter parameters, φ PZT (t) can quickly track the phase noise φ' c (t) and suppress it, realize real-time dynamic compensation, and ensure stable interference and coherent detection.

[0066] In this embodiment, multi-core optical fiber is used as the transmission medium. On the one hand, by using the space division multiplexing characteristics, the reference light and the signal light are transmitted synchronously in the same optical fiber. This synchronous transmission ensures that the two beams of light experience basically the same path during transmission. Therefore, the noise and jitter introduced by environmental disturbance is converted from differential mode noise to common mode noise, and the suppression of common mode noise is relatively easy to achieve. Therefore, the multi-core optical fiber, as the transmission channel of the reference light and the signal light, also plays a role in preliminary suppression of the relative disturbance noise of the two beams of light. On the other hand, the multi-core optical fiber can increase the communication channel. Since the inter-core crosstalk of the weakly coupled optical fiber is low, the transmission of optical communication information between different cores has almost no effect, thereby improving the transmission capacity. At the same time, the multi-core optical fiber is compatible with the existing single-mode optical fiber communication system, and is one of the solutions for the next generation of large-capacity space division multiplexing optical fiber communication. In addition, this embodiment uses a phase-locked loop to further eliminate the disturbance noise of the reference light and the signal light. Thus, in continuous low-frequency detection, noise interference is eliminated, and the results shown in FIGS. 3, 4, 5 and 6 can effectively improve the communication sensing effect.

[0067] In summary, the embodiment of the present application provides a seven-core fiber interferometer communication and sensing integrated device and an application method thereof. The application method comprises: a first beam splitter splits the light source emitted by a narrow linewidth laser into reference light and signal light; the reference light passes through a first coherent light transmitter to obtain modulated reference light, and the signal light passes through a second coherent transmitter to obtain modulated signal light; the modulated reference light passes through a first amplifier to obtain amplified modulated reference light, and the modulated signal light passes through a second amplifier to obtain amplified modulated signal light; the amplified modulated reference light and the amplified modulated signal light are output from a fan-in end through a multi-core fiber, and output reference light and output signal light are obtained from a fan-out end; the output reference light passes through a second beam splitter to obtain first output reference light and second output reference light, and the output signal light passes through a third beam splitter to obtain first output signal light and second output signal light; the first output reference light is demodulated through a first coherent receiver to obtain preliminary demodulated reference light; the first output signal light is demodulated through a second coherent receiver to obtain preliminary demodulated signal light; the second output reference light and the second output signal light are subjected to interference cancellation on the preliminary demodulated reference light and the preliminary demodulated signal light through a phase-locked loop to obtain final demodulated reference light and final demodulated signal light. In the embodiment of the present application, the multi-core fiber is used as a transmission medium. On the one hand, the space division multiplexing characteristic is utilized to enable the reference light and the signal light to be transmitted synchronously in the same fiber. This synchronous transmission ensures that the two beams of light experience substantially the same path during transmission. Therefore, the noise and jitter introduced by environmental disturbance are converted from differential mode noise to common mode noise, and the common mode noise is easier to suppress. Thus, the multi-core fiber, as the transmission channel of the reference light and the signal light, also plays a role in preliminarily suppressing the relative disturbance noise of the two beams of light. On the other hand, the multi-core fiber can increase the communication channel. Since the inter-core crosstalk of the weakly coupled fiber is low, the transmission of optical communication information between different cores has little effect, thereby improving the transmission capacity. At the same time, the multi-core fiber is compatible with the existing single-mode fiber communication system, and is one of the solutions for the next generation of large-capacity space division multiplexing optical fiber communication. In addition, the embodiment of the present application further eliminates the disturbance noise of the reference light and the signal light through the phase-locked loop. Thus, the noise interference is eliminated in continuous low-frequency detection, and the communication and sensing effect is prompted.

[0068] Obviously, the above-mentioned embodiment of the present application is only an example for clearly illustrating the present application, and is not a limitation on the embodiments of the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments are not enumerated, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

The application discloses a seven-core fiber interferometer communication and sensing integrated device. Comprise: A narrow linewidth laser (1), a first beam splitter (2), a first coherent transmitter (3), a second coherent transmitter (4), a first optical amplifier (5), a second optical amplifier (6), a fan-in end (7), a fan-out end (8), a multi-core optical fiber (9), a second beam splitter (10), a third beam splitter (11), a first coherent receiver (12), a second coherent receiver (13) and a phase-locked loop (14); The phase-locked loop (14) comprises an acousto-optic modulator (15), a piezoelectric ceramic fiber stretcher (16), a low-pass filter (17), a coupler (18), a balanced photodetector (19), a frequency mixer (20) and a band-pass filter (21); Wherein the narrow linewidth laser (1) is connected with the first coherent transmitter (3) and the second coherent transmitter (4) through the first beam splitter (2), the first coherent transmitter (3) is connected with the fan-in end (7) through the first optical amplifier (5), the first coherent transmitter (3) is connected with the fan-in end (7) through the second optical amplifier (6), the fan-in end (7) is connected with the fan-out end (8) through the multi-core optical fiber (9), the fan-out end (8) is connected with the first coherent receiver (12) and the acousto-optic modulator (15) through the second beam splitter (10), the fan-out end (8) is connected with the second coherent receiver (13) and the piezoelectric ceramic fiber stretcher (16) through the third beam splitter (11), the acousto-optic modulator (15) and the piezoelectric ceramic fiber stretcher (16) are connected with the balanced photodetector (19) through the coupler (18), the balanced photodetector (19) is connected with the frequency mixer (20) through the band-pass filter (21), the piezoelectric ceramic fiber stretcher (16) is connected with the frequency mixer (20) through the frequency mixer (20), and the acousto-optic modulator (15) is connected with the frequency mixer (20). The application method of the seven-core fiber interferometer communication and sensing integrated device, the seven-core fiber interferometer communication and sensing integrated device of application right 1, characterized in that, Comprise the following steps: S1: the first beam splitter splits the light source emitted by the narrow linewidth laser into reference light and signal light; S2: the reference light passes through the first coherent light transmitter to obtain modulated reference light, and the signal light passes through the second coherent transmitter to obtain modulated signal light; S3: the modulated reference light passes through the first amplifier to obtain amplified modulated reference light, and the modulated signal light passes through the second amplifier to obtain amplified modulated signal light; S4: the amplified modulated reference light and the amplified modulated signal light pass through the multi-core optical fiber from the fan-in end to the fan-out end Output, to obtain output reference light and output signal light; S5: the output reference light passes through the second beam splitter to obtain first output reference light and second output reference light, and the output signal light passes through the third beam splitter to obtain first output signal light and second output signal light; S6: the first output reference light passes through the first coherent receiver to be demodulated to obtain preliminary demodulated reference light; The first output signal light passes through the second coherent receiver to be demodulated to obtain preliminary demodulated signal light; S7: The second output reference light and the second output signal light are subjected to interference cancellation of the preliminary demodulation reference light and the preliminary demodulation signal light through a phase-locked loop to obtain the final demodulation reference light and the final demodulation signal light. The application method of the seven-core fiber interferometer communication and sensing integrated device according to claim 2, characterized in that, In step S2, the reference light is subjected to dual-polarization QAM signal modulation through a first coherent light transmitter to obtain modulated reference light, and the signal light is subjected to dual-polarization QAM signal modulation through a second coherent transmitter to obtain modulated signal light. The application method of the seven-core fiber interferometer communication and sensing integrated device according to claim 2, characterized in that, In step S2, the reference light is subjected to dual-polarization QAM signal modulation through a first coherent light transmitter to obtain modulated reference light, and the signal light is subjected to dual-polarization QAM signal modulation through a second coherent transmitter to obtain modulated signal light. The application method of the seven-core fiber interferometer communication and sensing integrated device according to claim 4, characterized in that, In step S6, the DC component is first removed through a frequency offset compensation and DC removal algorithm, then the first output reference light is demodulated through a first coherent receiver to obtain the preliminary demodulation reference light, and the first output signal light is demodulated through a second coherent receiver to obtain the preliminary demodulation signal light. The application method of the seven-core fiber interferometer communication and sensing integrated device according to claim 2, characterized in that, In step S4, the amplified modulated reference light is output from the fan-out end through one core of the multi-core optical fiber, and the amplified modulated signal light is output from the fan-out end through any core of the multi-core optical fiber except the one core to obtain the output reference light and the output signal light. The application method of the seven-core fiber interferometer communication and sensing integrated device according to claim 2, characterized in that, In step S7, the second output reference light is subjected to frequency shift through a 40MHz acousto-optic modulator and then enters the phase-locked loop. The application method of the seven-core fiber interferometer communication and sensing integrated device according to claim 2, characterized in that, In step S7, the phase-locked loop is composed of a balanced photodetector, a loop filter and a fiber stretcher, the balanced photodetector coherently detects the mixed second output reference light and the second output signal light to complete the conversion of the optical signal to the electrical signal and remove the common-mode noise. The application method of the seven-core fiber interferometer communication and sensing integrated device according to claim 8, characterized in that, In step S7, the 40MHz signal is filtered out through a band-pass filter, the 40MHz electrical signal is down-converted to a base frequency signal after entering a mixer, so that the phase information is detected, the disturbed phase information is compensated in real time through a loop filter and a fiber stretcher, and the base frequency electrical signal forms an error signal after passing through the loop filter and then is fed back to the fiber stretcher in the control link to compensate the phase information. The application method of the seven-core fiber interferometer communication and sensing integrated device according to claim 8, characterized in that, In step S7, the second output reference light and the second output signal light are subjected to interference cancellation of the preliminary demodulation reference light and the preliminary demodulation signal light through a phase-locked loop to obtain the final demodulation reference light and the final demodulation signal light. The incoherent probe photocurrent is: where r is the responsivity of BPD, P s and P r are the carrier powers of the signal light and the reference light, and ω IF = ω s - ω r is the frequency difference between the signal light and the local light, φ e = φ s (t) - φ r (t) is the phase difference between the signal light and the reference light, i.e. the signal to be demodulated, φ c is the beat noise caused by the laser phase noise and the relative disturbance noise of the laser caused by the environmental disturbances such as temperature change and vibration during the fiber transmission, which is the main noise source of the interference demodulator. The noise is mainly in the low frequency region and will seriously affect the demodulation signal, φ n (t) is the phase noise introduced by the modulated communication signal. Since the bandwidth of the communication signal is much higher than that of the vibration signal, φ n (t) is also a wide bandwidth signal, and the power in the local frequency band is much lower than that of the carrier signal. After mixing and low pass filtering, only the last three terms of the phase term in the sinusoidal signal are left: φ = φ e (t) + φ' c (t) + φ' n (t). When passing through the PLL, the error signal filtered by the loop is converted into a strong voltage control PZT, which compensates φ' c (t), at this time, i PD (t) changes to: φ PZT (t) is the phase change introduced by PZT, by setting appropriate filter parameters, φ PZT (t) can quickly track the phase noise φ' c (t) and suppress it, realize real-time dynamic compensation, and ensure stable interference and coherent detection.

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