A forward optical fiber sensing and communication fusion system based on hollow-core-single-mode parallel link

Abstract

This invention discloses a forward fiber optic sensing fusion system based on a hollow-core-single-mode parallel link, comprising an optical transmitting module, a transmission link modulation module, a parallel transmission link, and an optical receiving and signal processing module. The parallel transmission link consists of a hollow-core fiber link and a single-mode fiber link arranged in parallel, simultaneously carrying communication signals during forward transmission and generating corresponding disturbance responses under external vibration. The optical receiving and signal processing module includes two structurally identical link processing units, each comprising an optical coupler, a polarization controller, a polarization beam splitter, a low-speed photodetector, and a high-speed photodetector. The optical coupler splits the light from the transmission link into a communication optical path and a sensing optical path. The polarization controller and polarization beam splitter are located on the sensing optical path, decomposing the optical signal into orthogonal polarization components, and the low-speed photodetector detects vibration disturbance signals. This invention achieves the fusion of communication and sensing functions without requiring additional detection light sources or independent sensing devices.

Description

Technical Field

[0001] This invention relates to the field of fiber optic communication and fiber optic sensing fusion, specifically to a forward fiber optic sensing fusion system based on a hollow-single-mode parallel link. Background Technology

[0002] With the increasing demands of data centers for bandwidth, speed, and stability, how to achieve real-time monitoring and maintenance while ensuring high-speed data transmission has become a pressing issue in the field of fiber optic communication. Traditional fiber optic sensing technologies such as fiber optic gratings (FBG) and distributed fiber optic sensing (such as OTDR), while capable of vibration monitoring, have the following shortcomings:

[0003] 1. Additional hardware requirements: Traditional sensing systems typically require separate detection light sources and sensors, which increases the complexity and cost of system deployment.

[0004] 2. Limited Integration of Communication and Sensing: Most existing systems cannot simultaneously achieve high-speed data transmission and real-time sensing detection, resulting in underutilization of fiber optic resources. Some sensing signals occupy fiber optic communication bandwidth resources, further limiting the overall performance of the system.

[0005] 3. Insufficient positioning accuracy: In long-distance optical fiber transmission, vibration positioning accuracy is limited by the system's group velocity difference, dispersion, and signal processing capabilities.

[0006] 4. Insufficient single-span transmission capacity: The energy returned by backscattering can reach up to 40 kilometers, and since fiber amplifiers (such as EDFA) are generally equipped with isolators, this has an adverse effect on multi-span transmission. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention proposes a forward fiber optic sensing fusion system based on a hollow-single-mode parallel link. This system can achieve high-precision vibration detection and positioning without affecting high-speed data transmission, and is particularly suitable for short- and long-distance application scenarios such as data center interconnection.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A forward optical fiber sensing fusion system based on a hollow-single-mode parallel link includes an optical transmitting module, a transmission link modulation module, a parallel transmission link, and an optical receiving and signal processing module connected in sequence.

[0010] The parallel transmission link consists of a hollow fiber link and a single-mode fiber link set in parallel, which are used to carry communication signals simultaneously during forward transmission and generate corresponding disturbance responses under external vibration.

[0011] The transmission link modulation module is disposed on the parallel transmission link;

[0012] The optical receiving and signal processing module includes two identical link processing units and a demodulator connected to the two link processing units. The link processing unit includes an optical coupler, a polarization controller, a polarization beam splitter, a low-speed photodetector, and a high-speed photodetector. The optical coupler is used to split the light of the transmission link into a communication optical path and a sensing optical path. The polarization controller and the polarization beam splitter are sequentially arranged on the sensing optical path to decompose the optical signal into orthogonal polarization components, and the low-speed photodetector detects vibration disturbance signals.

[0013] The high-speed photodetector is located on the communication optical path and is used to detect communication signals;

[0014] The demodulator is used to acquire and process the electrical signals output by the photodetector.

[0015] Furthermore, the light emitting module includes a light source and a beam splitter connected in sequence;

[0016] The light source is used to generate a stable, continuous laser signal;

[0017] The beam splitter is used to split the modulated optical signal into two paths and inject them into the parallel transmission link respectively.

[0018] Furthermore, optical attenuators are also installed on the hollow-core fiber link and the single-mode fiber link respectively, which are used to adjust and match the optical power balance of the two links and reduce the impact of excessive input optical power on the optical signal quality.

[0019] Furthermore, the transmission link modulation module includes Mach-Zehnder electro-optic modulators respectively disposed on the hollow fiber link and the single-mode fiber link, and an arbitrary waveform generator for driving the Mach-Zehnder electro-optic modulators.

[0020] Furthermore, the light source is a narrow linewidth laser with a working wavelength of 1550 nm; the beam splitter is a beam splitter with a splitting ratio of 10:90; and the polarization beam splitter is a 50:50 polarization beam splitter.

[0021] A vibration localization method based on a forward fiber optic sensing fusion system includes the following steps:

[0022] S1: The vibration source is set at the connection point between the hollow fiber link and the optical receiving and signal processing module as a reference position; the signals of the hollow fiber link and the single-mode fiber link are synchronously sampled and digitally processed under the same clock reference to obtain the vibration response of the two links at the reference position, and the two vibration responses are cross-correlated to obtain the reference delay difference, which is defined as the link calibration delay difference τ0.

[0023] S2: Obtain the real-time vibration response of the hollow fiber link and the single-mode fiber link under the action of the vibration source to be located, and perform cross-correlation processing on the two real-time vibration responses to obtain the real-time response delay difference τ. m ;

[0024] S3: Perform a differential operation between the real-time response delay difference and the link calibration delay difference to obtain the effective delay difference Δt for vibration localization, and obtain the distance Z from the vibration location to the optical receiving and signal processing module based on the effective delay difference Δt. m :

[0025]

[0026]

[0027] Where n1 and n2 are the group refractive indices of single-mode light and hollow fiber, respectively; and c is the speed of light.

[0028] Furthermore, the vibration source is a piezoelectric ceramic vibrating ring.

[0029] Furthermore, before acquiring the vibration response of the hollow fiber link and the single-mode fiber link, the polarization state of the output light of the two links is adjusted by a polarization controller to match the polarization axis of the corresponding polarization beam splitter. When vibration is applied to the fiber link, the polarization state of the output light is disturbed, causing a change in the optical power distribution of the two orthogonal polarization output ports of the polarization beam splitter, and the change in optical power distribution is converted into a vibration response signal.

[0030] The beneficial effects of this invention are as follows:

[0031] (1) No additional sensing light source and hardware required: This invention directly uses the communication modulated optical signal as the sensing carrier, and the communication signal and the sensing signal are transmitted in the same forward optical fiber link and the communication demodulation and vibration sensing processing are completed at the same receiving end, realizing the integration of communication and sensing functions. No additional detection light source or independent sensing device is required, reducing system complexity and deployment cost.

[0032] (2) Fully compatible with forward high-speed communication architecture: This invention does not rely on backscattered or reflected signals and is suitable for multi-span, long-distance high-speed optical communication systems.

[0033] (3) Long-distance positioning performance is improved; This invention utilizes the significant group velocity difference between hollow fiber and single-mode fiber to increase the time delay difference with increasing distance, thereby improving positioning accuracy and stability.

[0034] (4) Applicable to data center interconnection scenarios: In high-bandwidth, low-latency optical interconnection systems, this invention can utilize existing optical fiber transmission resources to simultaneously achieve high-speed data communication and vibration detection, enabling coordinated operation of communication transmission and link status awareness, and is suitable for large-scale, low-latency network deployments. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the forward optical fiber inductive fusion system based on a hollow-single-mode parallel link according to Embodiment 1 of the present invention.

[0036] Figure 2 This is a schematic diagram of the forward fiber optic inductive fusion system based on a hollow-single-mode parallel link according to Embodiment 2 of the present invention.

[0037] Figure 3 This is a flowchart illustrating the vibration localization method for an optical fiber sensing fusion system based on Example 1.

[0038] Figure 4 This is a schematic diagram showing the location where the vibration source is placed at the connection point between the hollow fiber optic link and the optical receiving and signal processing module in Example 1.

[0039] Figure 5 This is a schematic diagram of a forward fiber optic inductive fusion system based on a hollow-single-mode parallel link, as described in Example 1.

[0040] Figure 6 This is a schematic diagram showing the response signal and cross-correlation time delay difference results of the PZT vibration generated by the system based on Example 1, wherein, Figure 6 (a) in the figure represents the vibration excitation signal applied to the PZT; Figure 6 (b) and Figure 6 (c) in the figure represents the vibration response signals detected by the single-mode fiber optic link and the hollow fiber optic link, respectively.

[0041] Figure 7 The results show the positioning performance of the system based on Example 1 under different vibration conditions. Figure 7 (a) shows the vibration localization results at different sensing distances, illustrating the estimated position and standard deviation of each test location; Figure 7(b) to (e) in the figure represent the repeated positioning results when the sensing distance is 400 m, 600 m, 700 m and 900 m, respectively.

[0042] Figure 8 This is a schematic diagram illustrating the communication performance test results of the system based on Example 1; wherein, Figure 8 (a) shows the test results of communication signals in hollow-core fiber links and single-mode fiber links; Figure 8 (b) in the figure shows the bit error rate test results of the two communication signals under different received optical power conditions. Detailed Implementation

[0043] The present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. The purpose and effects of the present invention will become clearer. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0044] Example 1

[0045] like Figure 1 As shown, in this embodiment, the optical emitting module 1 includes a light source 101 and a beam splitter 102 connected in sequence. The light source 101 is used to generate a stable continuous laser signal and can be a narrow-linewidth laser with a working wavelength of 1550 nm. In this embodiment, there is only one light source 101, so the optical emitting module 1 also includes a beam splitter 102, which is used to split the unmodulated optical signal into two paths and inject them into parallel transmission links respectively. The beam splitter can be a beam splitter with a splitting ratio of 50:50.

[0046] The transmission link modulation module 2 is used to modulate the laser signal emitted by the light source for communication, generating a modulated optical signal carrying communication data. The transmission link modulation module 2 includes a Mach-Zehnder electro-optic modulator 203 mounted on the hollow-core fiber link and a Mach-Zehnder electro-optic modulator 204 mounted on the single-mode fiber link, as well as an arbitrary waveform generator 205 for driving the two Mach-Zehnder electro-optic modulators. To adjust and match the optical power of the two fiber links and reduce the impact of excessively high input optical power on the optical signal quality, the transmission link modulation module 2 also includes an optical attenuator 201 mounted on the hollow-core fiber link and an optical attenuator 202 mounted on the single-mode fiber link.

[0047] Parallel transmission link 3 consists of a hollow fiber link 303 and a single-mode fiber link 304 set in parallel, used to carry communication signals simultaneously during forward transmission and generate corresponding disturbance responses under external vibration. In addition, the hollow fiber link 304 is also equipped with a single-mode-hollow fiber adapter 1 301 and a single-mode-hollow fiber adapter 2 302 for adapting the connection between single-mode fiber and hollow fiber.

[0048] Because hollow-core fiber (HCF) and single-mode fiber (SMF) have significantly different group refractive indices, their group velocities are different, resulting in different arrival times for the response signals of the same vibration event in the two links.

[0049] The optical receiving and signal processing module 4 includes two identical link processing units, namely link processing unit one 401 and link processing unit two 402, and a demodulator 403 connected to the two link processing units. Link processing unit one 401 includes a beam splitter 401-1, a polarization controller 401-2, a polarization beam splitter 401-3, a low-speed photodetector 401-4, and a high-speed photodetector 401-5.

[0050] The beam splitter 401-1 is used to split the light of the transmission link into a communication optical path and a sensing optical path. The beam splitter can be selected with a splitting ratio of 10:90, 1:99 or other ratios according to the link requirements. The polarization controller 401-2 and the polarization beam splitter 401-3 are sequentially arranged on the sensing optical path to decompose the optical signal into orthogonal polarization components, and the vibration disturbance signal is detected by the low-speed photodetector 401-4. The high-speed photodetector 401-5 is located on the communication optical path and is used to detect the communication signal. The demodulator 403 is used to collect and process the electrical signals output by the low-speed photodetector 401-4 and the high-speed photodetector 401-5.

[0051] Example 2

[0052] In this embodiment, there are two light sources 101, so a beam splitter 102 is not needed. Figure 2 As shown.

[0053] like Figure 3 The diagram illustrates the flow of the vibration localization method for the fiber optic sensing fusion system based on Embodiment 1, specifically including:

[0054] Step 1: Place the vibration source at the connection point between the hollow fiber optic link and the optical receiver and signal processing module, such as... Figure 4 As shown, the reference position is used; under the same clock reference, the signals of the hollow fiber link and the single-mode fiber link are synchronously sampled and digitally processed to obtain the vibration response of the two links at the reference position, and the two vibration responses are cross-correlated to obtain the reference delay difference, which is defined as the link calibration delay difference τ0.

[0055] Step 2: Obtain the real-time vibration response of the hollow-core fiber link and the single-mode fiber link under the action of the vibration source to be located, and perform cross-correlation processing on the two real-time vibration responses to obtain the real-time response delay difference τ. m ;

[0056] Step 3: Perform differential calculation between the real-time response delay difference and the link calibration delay difference to obtain the effective delay difference Δt for vibration localization, and obtain the distance from the vibration location to the optical receiving and signal processing module based on the effective delay difference Δt.

[0057] The specific principle is as follows Figure 5 As shown, the communication optical signal is split and then enters a single-mode fiber link and a hollow-core fiber link respectively, and is transmitted forward along both links. When any position on the fiber link is subjected to external vibration disturbance, the vibration disturbance will cause changes in the local stress, birefringence state, and polarization state of the fiber at the corresponding position, causing the transmitted optical signal to carry vibration response information. The receiving end converts the polarization state change into a detectable electrical signal through a polarization beam splitter and a photodetector, thereby obtaining the vibration response in the single-mode fiber link and the hollow-core fiber link respectively.

[0058] Because single-mode fiber links and hollow-core fiber links have different equivalent group refractive indices, the propagation speed of optical signals differs between the two links. When the same vibration disturbance is applied to the two links, the arrival times of the corresponding vibration responses at the receiving end differ. By performing cross-correlation processing on the two vibration response signals, the time delay difference between the two responses can be extracted. Furthermore, by performing a differential operation between the time delay difference obtained at the measured location and the calibration time delay difference obtained at the reference location, the effective time delay difference Δt can be obtained, and the vibration occurrence location Z can be calculated based on this effective time delay difference. m Therefore, this invention enables forward vibration detection and localization using a communication link without additionally occupying communication spectrum resources.

[0059] Among them, the effective time delay difference and vibration location satisfy:

[0060]

[0061]

[0062] In the formula, The time delay difference between the two vibration responses at the location to be measured is given. n1 represents the calibration delay difference between the two vibration responses at the reference position; n1 and n2 are the group refractive indices of the single-mode fiber and the hollow-core fiber, respectively; and c is the speed of light in vacuum.

[0063] Therefore, this invention utilizes the inherent group delay difference between single-mode fiber and hollow fiber to convert vibration events into a measurable time delay difference between two forward transmission signals, thereby realizing forward vibration detection and localization based on the communication link without occupying additional communication spectrum resources.

[0064] Figure 6This is a schematic diagram showing the response signal and cross-correlation time delay difference results of the PZT vibration generated by the system based on Example 1, wherein, Figure 6 In the diagram, (a) represents the vibration excitation signal applied to the PZT; (b) and (c) represent the vibration response signals detected by the single-mode fiber link and the hollow-core fiber link, respectively. Figure 6 As can be seen from (b) and (c), the vibration disturbances generated by PZT can be effectively captured in both single-mode fiber links and hollow fiber links, indicating that both links have the ability to respond to external vibration events. Figure 8 In the figure, (d) represents the cross-correlation result of the two vibration response signals at the reference position and the measured position. Figure 6 As shown in (d) above, the vibration responses in single-mode fiber links and hollow-core fiber links exhibit significant cross-correlation peaks. These peaks can be used to extract the time delay difference between the two responses. In the experiment, the effective time delay difference was measured to be 950.8 ns. Based on the aforementioned positioning formula, the vibration location was calculated to be 610.4 m, which is quite close to the actual set location of 600 m, verifying the feasibility of this invention for vibration positioning based on time delay difference.

[0065] Figure 7 The results show the positioning performance test results of the system based on Example 1 under different vibration location conditions. In the experiment, 30 repeated measurements were performed at each test distance point. Figure 7 (a) shows the vibration localization results at different sensing distances, illustrating the estimated position and standard deviation of each test location; Figure 7 Images (b) to (e) show the repeated localization results at sensing distances of 400 m, 600 m, 700 m, and 900 m, respectively. Figure 7 It can be seen that the present invention can obtain relatively concentrated positioning results at different test distances, with small fluctuations in the positioning results, indicating that the method has good repeatability and stability. Further linear fitting of the measured and actual positions yielded a linearity of R² = 0.9986. These experimental results demonstrate a good linear correspondence between the measured vibration position and the actual vibration position, indicating that the present invention possesses high positioning accuracy, repeatability, and stability.

[0066] Figure 8 This is a schematic diagram illustrating the communication performance test results of the system based on Example 1. Wherein, Figure 8 (a) shows the communication signal test results in the hollow-core fiber link and the single-mode fiber link, which are used to show that the two links can still carry communication signals while realizing vibration sensing. Figure 8 (b) shows the bit error rate test results of the two communication signals under different received optical power conditions. Figure 8As shown in (b), within the tested received optical power range, the bit error rate of the communication signal in both the hollow-core fiber link and the single-mode fiber link is lower than the hard decision 7% HD-FEC threshold, indicating that the present invention can maintain good communication transmission performance while realizing vibration sensing function, thus verifying the feasibility of the communication and sensing fusion scheme.

[0067] Furthermore, when the parallel transmission link 3 of the present invention transmits signals in parallel with the hollow-core fiber link and the single-mode fiber link, it can transmit the same or different signals. The structure is symmetrical and can be extended to multiple pairs of HCF / SMF links.

[0068] It will be understood by those skilled in the art that the above descriptions are merely preferred examples of the invention and are not intended to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, those skilled in the art can still modify the technical solutions described in the foregoing examples or make equivalent substitutions for some of the technical features. All modifications and equivalent substitutions made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A forward fiber optic sensing fusion system based on a hollow-core single-mode parallel link, characterized in that, It includes an optical transmitting module, a transmission link modulation module, a parallel transmission link, and an optical receiving and signal processing module connected in sequence; The parallel transmission link consists of a hollow fiber link and a single-mode fiber link set in parallel, which are used to carry communication signals simultaneously during forward transmission and generate corresponding disturbance responses under external vibration. The transmission link modulation module is disposed on the parallel transmission link; The optical receiving and signal processing module includes two identical link processing units and a demodulator connected to the two link processing units; the link processing unit includes an optical coupler, a polarization controller, a polarization beam splitter, a low-speed photodetector, and a high-speed photodetector. The optical coupler is used to split the light of the transmission link into a communication optical path and a sensing optical path. The polarization controller and polarization beam splitter are sequentially arranged on the sensing optical path to decompose the optical signal into orthogonal polarization components, and the vibration disturbance signal is detected by the low-speed photodetector. The high-speed photodetector is located on the communication optical path and is used to detect communication signals; The demodulator is used to acquire and process the electrical signals output by the photodetector.

2. The forward fiber optic inductive fusion system based on a hollow-single-mode parallel link according to claim 1, characterized in that, The light emitting module includes a light source and a beam splitter connected in sequence; The light source is used to generate a stable, continuous laser signal; The beam splitter is used to split the modulated optical signal into two paths and inject them into the parallel transmission link respectively.

3. The forward fiber optic inductive fusion system based on a hollow-single-mode parallel link according to claim 1, characterized in that, Optical attenuators are also installed on the hollow-core fiber link and the single-mode fiber link respectively, which are used to adjust and match the optical power balance of the two links and reduce the impact of excessive input optical power on the optical signal quality.

4. The forward fiber optic inductive fusion system based on a hollow-single-mode parallel link according to claim 1, characterized in that, The transmission link modulation module includes Mach-Zehnder electro-optic modulators respectively disposed on the hollow fiber link and the single-mode fiber link, and an arbitrary waveform generator for driving the Mach-Zehnder electro-optic modulators.

5. The forward fiber optic inductive fusion system based on a hollow-single-mode parallel link according to claim 2, characterized in that, The light source is a narrow linewidth laser with a working wavelength of 1550 nm; the beam splitter is a beam splitter with a splitting ratio of 10:90; and the polarization beam splitter is a 50:50 polarization beam splitter.

6. A vibration localization method based on the forward optical fiber sensing fusion system based on a hollow-single-mode parallel link as described in claim 1, characterized in that, Includes the following steps: S1: The vibration source is positioned at the connection point between the hollow-core fiber link and the optical receiving and signal processing module, serving as a reference position. Under the same clock reference, the signals from the hollow-core fiber link and the single-mode fiber link are synchronously sampled and digitally processed to obtain the vibration responses of the two links at the reference position. The two vibration responses are then cross-correlated to obtain the reference delay difference, which is defined as the link calibration delay difference. ; S2: Obtain the real-time vibration response of the hollow fiber link and the single-mode fiber link under the action of the vibration source to be located, and perform cross-correlation processing on the two real-time vibration responses to obtain the real-time response delay difference. ; S3: Perform a differential operation between the real-time response delay difference and the link calibration delay difference to obtain the effective delay difference Δt for vibration localization, and obtain the distance Z from the vibration location to the optical receiving and signal processing module based on the effective delay difference Δt. m : ； ； Where n1 and n2 are the group refractive indices of single-mode light and hollow fiber, respectively; and c is the speed of light.

7. The vibration positioning method according to claim 6, characterized in that, The vibration source is a piezoelectric ceramic vibrating ring.

8. The vibration positioning method according to claim 6, characterized in that, Before acquiring the vibration response of the hollow fiber link and the single-mode fiber link, the polarization state of the output light of the two links is adjusted by a polarization controller to match the polarization axis of the corresponding polarization beam splitter. When vibration is applied to the fiber link, the polarization state of the output light is disturbed, causing the optical power distribution of the two orthogonal polarization output ports of the polarization beam splitter to change, and the change in optical power distribution is converted into a vibration response signal.

Images