Distributed fiber sensing method and apparatus based on uncertainty principle

Abstract

The application provides a distributed optical fiber sensing method and device based on an uncertainty principle, applied to the technical field of distributed optical fiber sensing, and light emitted by a detection light source is divided into first detection light and first reference light, wherein the coherence of the detection light source has no special requirement. The first detection light is incident to an optical fiber link to obtain backscattering light of the optical fiber link. Based on the first reference light, the backscattering light and an auxiliary light source, the backscattering phase of each scattering position in the optical fiber link is extracted, so that distributed sensing based on continuous light backscattering is realized, and then distributed optical fiber vibration sensing is realized.

Description

Technical Field

[0001] This invention relates to the field of distributed optical fiber sensing technology, and specifically to a distributed optical fiber sensing method and apparatus based on the uncertainty principle. Background Technology

[0002] As the backbone of modern information society, optical fibers have been laid extensively around the world. Distributed optical fiber vibration sensing utilizes existing optical fiber networks to monitor vibration events along the link and has been widely used in fields such as traffic monitoring, infrastructure health monitoring, earthquake monitoring, and marine hydrological monitoring.

[0003] In a forward interferometer structure, the forward-propagating laser carries vibration information along the fiber optic link, and its phase is demodulated at the receiving end for extraction. However, since the light travels forward in the fiber to sense information along the fiber optic link, the demodulation at the receiving end yields all the information along the fiber optic link (i.e., the integration of various information along the fiber optic link), making distributed sensing difficult.

[0004] In a backscatterer structure, incident narrow-linewidth pulsed light propagates along an optical fiber link, generating backscattered light along the line. Since the scattered light at different locations has different echo delays, the receiver can distinguish information from different locations along the line based on arrival time, thus achieving distributed vibration sensing. However, this structure typically requires narrow-linewidth pulsed light to ensure the coherence and phase demodulation stability of the scattered signal, placing high demands on the linewidth of the probe light source and the system's coherence conditions. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a distributed optical fiber sensing method and apparatus based on the uncertainty principle to realize distributed optical fiber vibration sensing.

[0006] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0007] The first aspect of this invention discloses a distributed optical fiber sensing method based on the uncertainty principle. The method is implemented based on the Heisenberg uncertainty principle and includes:

[0008] The light emitted by the detection light source is divided into a first detection light and a first reference light;

[0009] The first probe light is incident on the optical fiber link to obtain the backscattered light of the optical fiber link;

[0010] Based on the first reference light, the backscattered light, and the auxiliary light source, the backscattered phase at each scattering position in the optical fiber link is extracted, and the backscattered phase is used to realize distributed optical fiber vibration sensing.

[0011] Preferably, the detection light source is suitable for any laser light source.

[0012] Preferably, based on the first reference light, the backscattered light, and the auxiliary light source, the backscattered phase at each scattering position in the optical fiber link is extracted, including:

[0013] The light emitted by the auxiliary light source is divided into first auxiliary light and second auxiliary light;

[0014] The first auxiliary light and the backscattered light are coherently detected to obtain the first radio frequency signal;

[0015] The first reference light and the second auxiliary light are coherently detected to obtain the second radio frequency signal;

[0016] Based on the first radio frequency signal and the second radio frequency signal, the backscatter phase of each scattering position in the optical fiber link is extracted.

[0017] Preferably, based on the first radio frequency signal and the second radio frequency signal, the backscattering phase at each scattering location in the optical fiber link is extracted, including:

[0018] The first radio frequency signal and the second radio frequency signal are orthogonalized respectively to obtain a first orthogonal signal of the first radio frequency signal and a second orthogonal signal of the second radio frequency signal;

[0019] The second orthogonal signal is time-delayed using the delay duration corresponding to the scattering position i in the optical fiber link, with the initial value of i being 0;

[0020] The first orthogonal signal and the second orthogonal signal after time delay are transformed to obtain a first digital signal sequence and a second digital signal sequence.

[0021] Based on the first digital signal sequence and the second digital signal sequence, the backscattering phase at scattering position i is extracted;

[0022] Increment i by 1, and return to the step of using the delay duration corresponding to the scattering position i in the optical fiber link to time delay the second orthogonal signal.

[0023] Preferably, a transformation operation is performed on the first orthogonal signal and the second orthogonal signal after time delay to obtain a first digital signal sequence and a second digital signal sequence, including:

[0024] The first orthogonal signal and the second orthogonal signal after time delay are cross-multiplied, and the cross-multiplication results are added and subtracted respectively to obtain the first digital signal sequence and the second digital signal sequence.

[0025] Preferably, based on the first digital signal sequence and the second digital signal sequence, extracting the backscattering phase at scattering position i includes:

[0026] The first digital signal sequence and the second digital signal sequence are subjected to moving average processing to obtain the moving average processing result corresponding to the scattering position i;

[0027] Phase demodulation processing is performed on the moving average processing result corresponding to the scattering position i to extract the backscattering phase of the scattering position i.

[0028] Preferably, the backscattered light is backscattered Rayleigh light, backscattered Raman light, or backscattered Brillouin light.

[0029] Preferably, the linewidth of the auxiliary light source is smaller than the linewidth of the detection light source.

[0030] Preferably, after extracting the backscattering phase at each scattering location in the optical fiber link, the method further includes:

[0031] The vibration waveform at the scattering location is determined using the backscattering phase at the scattering location.

[0032] A second aspect of this invention discloses a distributed optical fiber sensing device based on the uncertainty principle. The device is implemented based on the Heisenberg uncertainty principle and includes:

[0033] The beam splitting unit is used to split the light emitted by the detection light source into a first detection light and a first reference light;

[0034] A transmission unit is used to incident the first probe light onto the optical fiber link to obtain the backscattered light of the optical fiber link;

[0035] The extraction unit is used to extract the backscatter phase at each scattering position in the optical fiber link based on the first reference light, the backscattered light, and the auxiliary light source. The backscattered phase is used to realize distributed optical fiber vibration sensing.

[0036] Based on the above embodiments of the present invention, a distributed optical fiber sensing method and apparatus based on the uncertainty principle is provided. The light from a detection source is divided into a first detection light and a first reference light, wherein there are no special requirements for the coherence of the detection source. The first detection light is incident on an optical fiber link to obtain the backscattered light of the optical fiber link. Based on the first reference light, the backscattered light, and an auxiliary light source, the backscattered phase at each scattering position in the optical fiber link is extracted, thereby realizing distributed sensing based on continuous backscattering, and further realizing distributed optical fiber vibration sensing. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0038] Figure 1 A flowchart illustrating a distributed optical fiber sensing method based on the uncertainty principle, provided for an embodiment of the present invention;

[0039] Figure 2 A flowchart for extracting the backscattering phase of the scattering position provided in an embodiment of the present invention;

[0040] Figure 3 Another flowchart for extracting the backscattering phase of the scattering position provided in an embodiment of the present invention;

[0041] Figure 4 This is a structural block diagram of a distributed optical fiber sensing system provided in an embodiment of the present invention;

[0042] Figure 5 This is a structural block diagram of a distributed optical fiber sensing device based on the uncertainty principle, provided for an embodiment of the present invention. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] In this application, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0045] With the development of information technology, optical fibers have been laid extensively around the world. Distributed optical fiber vibration sensing utilizes existing optical fiber networks to monitor vibration events along the link and has been widely applied in fields such as traffic monitoring, infrastructure health monitoring, earthquake monitoring, and marine hydrological monitoring. For forward interferometer structures, the forward-transmitted laser carries vibration information along the optical fiber link, and its phase is demodulated and extracted at the receiving end. Backscattering-based distributed optical fiber sensing schemes, on the other hand, utilize the Rayleigh, Raman, and Brillouin scattering mechanisms in optical fibers to acquire environmental information by measuring changes in the phase, intensity, or frequency of the light signal. Due to its advantages such as high spatial resolution, strong anti-interference capability, and cost-effectiveness, it has been widely researched and applied.

[0046] Rayleigh scattering is an elastic, linear scattering phenomenon caused by refractive index inhomogeneities in optical fibers. The frequency of the scattered light is the same as that of the incident light. When the fiber is subjected to mechanical vibration or temperature changes, the phase of the scattered light changes, thus generating a measurable signal. It offers high spatial resolution, reaching the meter level, but has relatively low sensitivity and is significantly affected by Rayleigh fading. Distributed acoustic sensing (DAS) and distributed vibration sensing (DVS) are used to monitor the vibration of structures such as bridges, tunnels, and pipelines, as well as for traffic flow monitoring and earthquake monitoring.

[0047] Raman scattering is inelastic scattering caused by molecular vibrations in optical fibers, resulting in a frequency difference between the scattered light and the incident light. Temperature changes affect the probability of molecular vibrations, thus altering the relative intensities of the Stokes and anti-Stokes peaks in the Raman spectrum, which can be used for temperature sensing. It offers high sensitivity but the scattered signal is relatively weak, requiring the use of highly sensitive detectors. Distributed temperature sensing (DTS) is used to monitor the temperature of equipment such as oil wells, pipelines, and transformers, as well as soil moisture monitoring.

[0048] Brillouin scattering is an inelastic scattering caused by the interaction of acoustic and optical waves in an optical fiber, resulting in a frequency difference between the scattered light and the incident light. The propagation of the acoustic wave leads to a change in the Brillouin frequency (BFS), which can be used for strain and temperature sensing. It offers high sensitivity, allowing simultaneous measurement of strain and temperature, but the scattered signal is weak, requiring highly sensitive detectors and stimulus light. Distributed strain sensing (DSS) and distributed temperature sensing (DTS) are used to monitor the strain and temperature of structures such as bridges, tunnels, and pipelines, as well as the temperature of equipment such as oil wells and pipelines.

[0049] Research has revealed that, for a forward interferometer structure, the forward-transmitted laser carries vibrational information along the fiber optic link, and its phase is extracted at the receiving end through demodulation. However, since the light travels forward through the fiber to sense information along the fiber optic link, the demodulation at the receiving end yields all the information along the fiber optic link (i.e., the integration of various information along the fiber optic link), making distributed sensing difficult.

[0050] Backscattering technology leverages the characteristic that each location in an optical fiber link generates backscattered light. By detecting the backscattered light returning from each location at the transmitter, each scattering point can be considered a detection channel, making distributed positioning easy. However, in practice, a single optical pulse is typically driven into the fiber, requiring modulation of the light source, which is not easily compatible with widely used optical fiber communication systems. Traditional methods determine location by the time of flight of the backscattered light back to the transmitter, and their spatial resolution is limited by the pulse width (narrower pulses are practically difficult to achieve and expensive). For phase-based backscattering schemes (such as Φ-OTDR), the backscattered light needs to be coherently demodulated with the local reference light at the transmitter, thus usually requiring a light source with good coherence. Such light sources are typically expensive, further limiting the fundamental compatibility of traditional methods with communication systems.

[0051] To address this, the present invention proposes a distributed optical fiber sensing method and apparatus based on the uncertainty principle. The light from the detection source is divided into a first detection light and a first reference light. The first detection light is incident on the optical fiber link to obtain the backscattered light of the optical fiber link. Based on the first reference light, the backscattered light, and the auxiliary light source, the backscattered phase at each scattering position in the optical fiber link is extracted, thereby realizing distributed sensing based on continuous backscattering, and ultimately achieving distributed optical fiber vibration sensing.

[0052] It is worth noting in advance that the distributed optical fiber sensing method based on the uncertainty principle proposed in this invention is a new optical fiber distributed sensing architecture based on quantum physics. Heisenberg proposed a photon spatial position measurement limit from a quantum physics perspective, which differs from the classical physics perspective, namely the uncertainty relationship between position and momentum. ,in, Let be the uncertainty of the photon's spatial position. Let be the uncertainty of the photon momentum, and h be Planck's constant.

[0053] From a quantum perspective, the measurement uncertainty of a photon's spatial position depends on the measurement uncertainty of its momentum. For distributed fiber optic sensing systems, this can be deduced... ,in, For the linewidth of the light source, The speed at which light travels in an optical fiber. The greater the uncertainty of the photon's spatial position (i.e. the spatial position uncertainty that the distributed fiber optic sensing system can distinguish), the better its spatial resolution. This leads to a distributed fiber optic sensing method that is fundamentally different from the classical mechanism.

[0054] Based on the above, the implementation principle of this invention is as follows: Continuous light emitted from a general light source is transmitted into an optical fiber link (without additional modulation), and its backscattered light (which can be simply referred to as backscattered light) is used for detection. For the backscattered superposition signal along the optical fiber link, an auxiliary light source is used to coherently downconvert the backscattered light and the reference light respectively. Interference recording is performed on the backscattered light carrying link information and the reference light carrying photon information of the general light source itself. After sampling, the information of each scattering position in the optical fiber link is extracted using the self-coherence characteristics of the light source (essentially based on the "capture" of photons based on the Heisenberg uncertainty principle), thereby achieving a distributed sensing scheme based on continuous light backscattering.

[0055] Therefore, the proposed solution can achieve distributed sensing using only the backscattered signal of a general continuous light source, without requiring modulation or modification of the original light source. It is directly compatible with existing communication systems and directly uses the light emitted by an SFP (Small Form-factor Pluggable) optical module for sensing. Furthermore, since the extraction of link information at a certain location utilizes the self-coherence characteristics of the general light source itself, low phase noise of the light source is not required. In fact, the higher the phase noise, the better it is for improving the resolution of the proposed solution, fundamentally solving the problem that the spatial resolution of traditional solutions is limited by pulse width. The following will describe the invention in detail through various embodiments.

[0056] See Figure 1 The diagram illustrates a flowchart of a distributed optical fiber sensing method based on the uncertainty principle provided by an embodiment of the present invention. This distributed optical fiber sensing method is based on the Heisenberg uncertainty principle and includes:

[0057] Step S101: Divide the light emitted by the detection light source into a first detection light and a first reference light.

[0058] In the specific implementation step S101, the light emitted by the detection light source is split into two by an optical fiber coupler (this is just an example; other devices can also be used for light splitting). One path of light is called the first detection light, and the other path of light is called the first reference light. The purpose of this is to record the noise of the detection light source at different times (i.e., the momentum uncertainty of photons), so as to facilitate the subsequent extraction of phase information at different scattering positions in the optical fiber link through time delay to achieve distributed sensing.

[0059] In some embodiments, the detection light source can be a phase noise level of 1. The light emitted by the laser light source can be expressed as formula (1).

[0060] (1);

[0061] In formula (1), To detect the light frequency of the light source, To detect the phase noise of the light source itself, To detect the amplitude noise of the light source, t is time. This is to detect the time-domain expression of the output light field of the light source (i.e., the photoelectric field of a typical continuous light source).

[0062] It should be noted that in practical applications, this scheme does not have special requirements for the coherence of the detection light source. The detection light source used in this scheme is applicable to any laser light source. For example, the detection light source is not limited to specially modulated pulse light, frequency sweep light, etc.

[0063] Step S102: The first probe light is incident on the fiber optic link to obtain the backscattered light of the fiber optic link.

[0064] In the specific implementation of step S102, the first probe light is incident on the optical fiber link through the optical circulator, and the backscattered light returning along the optical fiber link is obtained through the optical circulator. That is, the backscattered light of the optical fiber link is looped back at the transmitting end through the optical circulator.

[0065] Specifically, the first probe light is injected into the fiber optic link to be tested through the optical circulator. When the first probe light propagates in the fiber optic link, it will generate backscattered light at various scattering positions along the line. The backscattered light returns to the optical circulator along the original fiber optic link. The backscattered light is output from the other port of the optical circulator to the first photodetector (PD), which is denoted as PD1.

[0066] In some specific embodiments, the backscattered light is backscattered Rayleigh light, backscattered Raman light, or backscattered Brillouin light. That is, the distributed fiber optic sensing method based on the uncertainty principle proposed in this invention is applicable not only to backscattered Rayleigh scattering distributed sensing, but also to backscattered Raman scattering distributed sensing and backscattered Brillouin scattering distributed sensing.

[0067] Let's take the scenario of "backscattered light being backscattered Rayleigh light" as an example to explain the backscattered light in an optical fiber link: According to the Rayleigh scattering principle, after the first probe light emitted by the probe light source enters the optical fiber link, there will be backscattered light at every scattering point in the optical fiber link (which is backscattered Rayleigh light in this example). Therefore, the backscattered light received by the optical circulator at the transmitting end... It can be expressed as formula (2).

[0068] (2);

[0069] In formula (2), i represents the sequence number of the light scattered back from each scattering position of the optical fiber link. In fact, the scattering positions are continuous (scattering position 0, scattering position 1, scattering position 2, ..., respectively), so i can be represented as scattering position i. Let i be the delay time corresponding to the scattering position i. This indicates that the backscattered light from scattering position i has traveled a distance greater than that of the first reference light. Time delay. This represents the phase of the backscattered light reflected back from scattering position i. To detect the light frequency of the light source, To detect the amplitude noise of the light source, To detect the amplitude noise of the light source, it has undergone... Delay, where t is time.

[0070] It is worth noting that the backscattered light returning from the scattering position has a time delay relative to the first reference light, and this time delay is determined by the distance from the scattering position to the transmitter. If the distance between the scattering position i and the transmitter is L... i The first probe light propagates from the transmitter to the scattering position i, and the backscattered light at scattering position i returns to the transmitter, undergoing a round trip propagation. Therefore It is represented by formula (3).

[0071] (3);

[0072] In formula (3), n is the effective refractive index of the optical fiber link and c is the speed of light in vacuum.

[0073] It should be noted that in a backscattered distributed sensing system, the transmitter and receiver are located at the same end. Specifically, the transmitter refers to the end where the detection light source and optical circulator are located (that is, the end where the first detection light is injected into the optical fiber link). Since the backscattered light returns to the same end and is detected locally, the receiver is the first photodetector (PD1) and the second photodetector (denoted as PD2), which will be mentioned later.

[0074] Step S103: Based on the first reference light, backscattered light and auxiliary light source, extract the backscattered phase at each scattering position in the optical fiber link. The backscattered phase is used to realize distributed optical fiber vibration sensing.

[0075] It should be noted that the first reference light of the probe light source does not enter the fiber optic link under test, but is used locally as a reference branch to coherently probe with the light of the auxiliary light source. The role of the first reference light is to record the phase noise and amplitude noise of the probe light source itself, thereby providing a reference for subsequent digital domain delay matching and extraction of information from the corresponding scattering position.

[0076] In the specific implementation step S103, coherent detection, orthogonalization, time delay, and moving average processing are performed based on the first reference light, backscattered light, and auxiliary light source to extract the backscattered phase of each scattering position in the optical fiber link. The extracted backscattered phase of each scattering position is used to realize distributed optical fiber vibration sensing.

[0077] In some specific embodiments, the auxiliary light source can be a laser light source, and the linewidth of the auxiliary light source is smaller (much smaller) than that of the probe light source. Compared with the probe light source, the phase noise and amplitude noise of the auxiliary light source are negligible.

[0078] It should be noted that distributed fiber optic sensing essentially involves extracting vibrations along the fiber optic link, and these vibrations cause phase changes. Therefore, after extracting the backscattered phase at each scattering location in the fiber optic link, the vibration waveform at that scattering location is determined using the backscattered phase, thus achieving distributed fiber optic vibration sensing.

[0079] For example, one practical application scenario after applying this invention is: when a car passes through an optical fiber link, the vibration of the car will cause strain on the optical fiber, which will lead to a change in the light phase at the location of the car (i.e., the scattering position). Through this invention, the phase change caused by the car at that position (i.e., the backscattering phase) can be extracted. By analogy, the phase change caused by the car passing through each scattering position of the optical fiber link can be obtained, thereby realizing the car positioning or deducing other information.

[0080] In this embodiment of the invention, the light from the detection light source is divided into a first detection light and a first reference light. The first detection light is incident on the optical fiber link to obtain the backscattered light of the optical fiber link. Based on the first reference light, the backscattered light, and the auxiliary light source, the backscattered phase of each scattering position in the optical fiber link is extracted, thereby realizing distributed sensing based on continuous light backscattering, and further realizing distributed optical fiber vibration sensing.

[0081] Regarding the above embodiments of the present invention Figure 1 The step S103, which involves "extracting the backscattering phase at each scattering location in the fiber optic link," can be found in [reference needed]. Figure 2 This illustrates a flowchart of extracting the backscattering phase of the scattering position according to an embodiment of the present invention. Figure 2 Includes the following steps:

[0082] Step S201: Divide the light emitted by the auxiliary light source into a first auxiliary light and a second auxiliary light.

[0083] In the specific implementation step S201, the light emitted by the auxiliary light source is split into two by an optical fiber coupler (this is just an example; other devices can also be used for light splitting). One path of light is called the first auxiliary light, and the other path of light is called the second auxiliary light.

[0084] In some embodiments, the light emitted by the auxiliary light source can be expressed as formula (4).

[0085] (4);

[0086] In formula (4), The frequency of the light emitted by the auxiliary light source, where t is time. This is the time-domain expression for the output light field of the auxiliary light source (i.e., the photoelectric field of the auxiliary low-phase-noise light source).

[0087] Step S202: Perform coherent detection on the first auxiliary light and the backscattered light to obtain the first radio frequency signal.

[0088] In the specific implementation of step S202, at the receiving end, the backscattered light and the first auxiliary light of the auxiliary light source are downconverted and coherently detected to obtain the first radio frequency signal (denoted as E1(t)).

[0089] Specifically, the first auxiliary light and the backscattered light are downconverted and coherently detected by the first photodetector (PD1) to obtain the first radio frequency signal E1(t). The first radio frequency signal E1(t) is the backscattered signal, and the first radio frequency signal E1(t) is expressed as formula (5).

[0090] (5);

[0091] In formula (5), To detect the frequency difference of interference between the light source and the auxiliary light source.

[0092] Step S203: Perform coherent detection on the first reference light and the second auxiliary light to obtain the second radio frequency signal.

[0093] In the specific implementation step S203, the first reference light of the probe light source and the second auxiliary light of the auxiliary light source are down-converted and coherently probed to obtain the second radio frequency signal (denoted as E2(t)).

[0094] Specifically, the first reference light and the second auxiliary light are down-converted and coherently detected by the second photodetector (PD2) to obtain the second radio frequency signal E2(t). The second radio frequency signal E2(t) is the reference signal and is expressed as formula (6).

[0095] (6).

[0096] It should be noted that the function of the second radio frequency signal E2(t) is to serve as a reference signal for recording the phase noise of the probe light source. and amplitude noise .

[0097] Step S204: Based on the first radio frequency signal and the second radio frequency signal, extract the backscatter phase of each scattering position in the optical fiber link.

[0098] In the specific implementation step S204, the backscattering phase at each scattering position in the optical fiber link is extracted based on the first radio frequency signal E1(t) and the second radio frequency signal E2(t). For details of the backscattering phase extraction process, please refer to [link to relevant documentation]. Figure 3 Another flowchart is shown to extract the backscatter phase of the scattering location.

[0099] See Figure 3 This illustrates another flowchart for extracting the backscattering phase of the scattering position according to an embodiment of the present invention. Figure 3 Includes the following steps:

[0100] Step S301: Orthogonalize the first radio frequency signal and the second radio frequency signal respectively to obtain the first orthogonal signal of the first radio frequency signal and the second orthogonal signal of the second radio frequency signal.

[0101] In the specific implementation step S301, the first radio frequency signal E1(t) is orthogonalized using IQ mixing, other radio frequency or digital domain methods to obtain a pair of first orthogonal signals of the first radio frequency signal (denoted as E). 1_I (t) and E 1_Q (t)), and, orthogonalize the second radio frequency signal E2(t) to obtain a pair of second orthogonal signals of the second radio frequency signal (denoted as E(t)). 2_I (t) and E 2_Q (t)).

[0102] The first orthogonal signal is represented by formula (7), and the second orthogonal signal is represented by formula (8).

[0103] (7);

[0104] (8).

[0105] Step S302: Use the delay time corresponding to the scattering position i in the optical fiber link to delay the second orthogonal signal.

[0106] It should be noted that the initial value of i is 0.

[0107] In the specific implementation step S302, the delay time corresponding to the scattering position i in the optical fiber link is utilized. The second orthogonal signal is time-delayed.

[0108] For example: when i is 0, the delay time corresponding to scattering position 0 in the fiber optic link is used. The second orthogonal signal in formula (8) is time-delayed, and the second orthogonal signal after time delay is shown in formula (9).

[0109] (9).

[0110] Step S303: Perform a transformation operation on the first orthogonal signal and the second orthogonal signal after time delay to obtain a first digital signal sequence and a second digital signal sequence.

[0111] In the specific implementation of step S303, a transformation operation is performed on the first orthogonal signal and the second orthogonal signal after time delay to obtain the first digital signal sequence. ) and second digital signal sequence ( ).

[0112] Specifically, the first orthogonal signal and the second orthogonal signal after time delay are cross-multiplied, and the cross-multiplication results are added and subtracted respectively to obtain the first digital signal sequence. ) and second digital signal sequence ( ).

[0113] It should be noted that after time delaying the second orthogonal signal, the "time-delayed second orthogonal signal" is a digital signal sequence.

[0114] For example: utilizing the delay time corresponding to scattering position 0 in the optical fiber link. The second orthogonal signal in formula (8) is time-delayed, and then the first orthogonal signal and the time-delayed second orthogonal signal are transformed to obtain the first digital signal sequence ( ) and second digital signal sequence ( As shown in formulas (10) and (11).

[0115] (10);

[0116] (11);

[0117] In formula (10), the first term " "This represents the phase of the Rayleigh scattered light at scattering position 0." (That is, the items of interest) and their corresponding delay durations Squared amplitude noise at time The second item "Random noise introduced by Rayleigh scattering from all other scattering locations. Equation (11) is similar."

[0118] This will give the phase at scattering position 0, which contains the backscattered phase to be extracted. , And two digital signal sequences (i.e., the first digital signal sequence and the second digital signal sequence) of random noise introduced by other scattering locations.

[0119] Step S304: Based on the first digital signal sequence and the second digital signal sequence, extract the backscattering phase of scattering position i.

[0120] In the specific implementation step S304, the first digital signal sequence and the second digital signal sequence are subjected to moving average processing to obtain the moving average processing result corresponding to the scattering position i.

[0121] For example: the random noise terms introduced by backscattering at other scattering locations of the fiber optic link included in the above formulas (10) and (11) will be suppressed during the moving average process, and the " "and" "Then it will be preserved during the average sliding process (assuming the backscattering phase at scattering position 0)." Within the window length set by the moving average, it can be considered a constant and is therefore retained. The moving average processing result corresponding to the scattering position 0 is shown in formula (12).

[0122] (12);

[0123] In formula (12), the backscattering phase at the extraction scattering position 0 is... When (i=0), k is determined by amplitude noise " "Introduced in the moving average process."

[0124] Phase demodulation processing is performed on the moving average result corresponding to scattering position i to extract the backscattering phase of scattering position i. .

[0125] For example, if i=0, based on the moving average processing result corresponding to the scattering position 0 given by formula (12), the backscattering phase at the scattering position 0 can be obtained through the phase demodulation algorithm. .

[0126] Step S305: Increment i by 1, then return to step S302.

[0127] In the specific implementation of step S305, i is incremented by 1, and the process returns to step S302 to continue extracting the backscattering phase at the next scattering position.

[0128] Specifically, the backscattering phase at scattering position 0 is extracted. Then, i is incremented by 1 (i.e., i=1), and the process returns to step S302 to adjust the delay duration in formula (9). Change to Repeat steps S303 to S304 to obtain the backscattering phase at scattering position 1. ; and so on, the delay duration in formula (9) is changed one by one. Change to , Wait, then repeat steps S303 to S304 to obtain the backscattering phase at scattering position 2, scattering position 3, ... , …

[0129] The above embodiments of the present invention Figure 2 and Figure 3 This is an explanation of how to extract the backscatter phase at each scattering location in an optical fiber link.

[0130] It should be noted that the distributed optical fiber sensing method based on the uncertainty principle proposed in the present invention can be implemented by a corresponding distributed optical fiber sensing system, which is composed of various components. Here, we will illustrate one preferred example of the distributed optical fiber sensing system.

[0131] See Figure 4 The diagram shows a structural block diagram of a distributed optical fiber sensing system provided in an embodiment of the present invention. The distributed optical fiber sensing system includes at least: a detection light source 401, an auxiliary light source 402, an optical circulator 403, a first photodetector 404, and a second photodetector 405.

[0132] The light from the probe light source 401 is divided into a first probe light and a first reference light. The first probe light is incident on the optical fiber link through the optical circulator 403, and the backscattered light returning along the optical fiber link is obtained through the optical circulator 403.

[0133] The light from the auxiliary light source 402 is divided into a first auxiliary light and a second auxiliary light.

[0134] The first photodetector 404 performs down-conversion coherent detection on the first auxiliary light and the backscattered light to obtain the first radio frequency signal E1(t).

[0135] The second photodetector 405 performs down-conversion coherent detection on the first reference light and the second auxiliary light to obtain the second radio frequency signal E2(t).

[0136] Using the above embodiments of the present invention Figure 3 The proposed method extracts the backscattering phase at each scattering position in the optical fiber link based on the first radio frequency signal E1(t) and the second radio frequency signal E2(t).

[0137] In summary, regarding the distributed optical fiber sensing method based on the uncertainty principle proposed in this invention, the invention has the following beneficial effects:

[0138] 1. Compared to traditional fiber-optic back-to-back distributed sensing schemes, this invention utilizes the Heisenberg uncertainty principle (i.e., the uncertainty relationship between position and momentum). To achieve distributed fiber optic sensing, from a quantum perspective, the measurement uncertainty of the spatial position of a photon depends on the measurement uncertainty of the photon momentum. When applied to distributed fiber optic sensing technology, the greater the uncertainty of the photon momentum of the sensed light, the better its spatial resolution.

[0139] 2. This invention senses information through backscattered light from a continuous light source in an optical fiber link, and extracts the backscattered phase at the corresponding scattering position i by utilizing the momentum uncertainty of the photon itself. At this point, the spatial resolution depends on the photon momentum uncertainty, while the scattering information from other scattering locations is suppressed during the moving average process due to the incoherent characteristics of phase noise.

[0140] 3. Compared with traditional fiber optic backscattering distributed sensing schemes, this invention utilizes the backscattering signal of a continuous light source for distributed sensing, and does not require high coherence of the continuous light source. This characteristic makes the proposed scheme easily compatible with most fiber optic systems (such as fiber optic communication systems, fiber optic time and frequency synchronization systems, etc.), and has high compatibility. It can be used as a plug-in module to add distributed sensing functionality to the system.

[0141] 4. Compared with the traditional optical fiber back-to-back distributed sensing scheme, the distributed sensing of the present invention does not require modulation. The spatial resolution is no longer limited by the modulation pulse width, but is determined by the momentum uncertainty of the light source, which makes it easier to achieve a higher spatial resolution.

[0142] 5. This invention utilizes the phase noise of the detection light source itself, and does not require the detection light source to have good coherence (the better the coherence of the light source, the higher the cost), which can greatly reduce the cost of distributed optical fiber sensing systems.

[0143] Corresponding to the distributed optical fiber sensing method based on the uncertainty principle provided in the above embodiments of the present invention, see also... Figure 5The present invention also provides a structural block diagram of a distributed optical fiber sensing device based on the uncertainty principle. The device is based on the Heisenberg uncertainty principle and includes: a beam splitting unit 501, a transmission unit 502, and an extraction unit 503.

[0144] The beam splitting unit 501 is used to split the light emitted by the detection light source into a first detection light and a first reference light.

[0145] The detection light source is applicable to any laser light source.

[0146] The transmission unit 502 is used to incident the first probe light onto the optical fiber link to obtain the backscattered light of the optical fiber link.

[0147] In some embodiments, the transmission unit 502 is specifically used to: incident a first probe light onto the optical fiber link through an optical circulator, and obtain backscattered light returning along the optical fiber link through the optical circulator.

[0148] Among them, the backscattered light is either backscattered Rayleigh light, backscattered Raman light, or backscattered Brillouin light.

[0149] The extraction unit 503 is used to extract the backscatter phase at each scattering position in the optical fiber link based on the first reference light, the backscattered light and the auxiliary light source. The backscattered phase is used to realize distributed optical fiber vibration sensing.

[0150] The linewidth of the auxiliary light source is smaller than that of the detection light source.

[0151] Preferably, in some embodiments, the distributed fiber optic sensing device further includes:

[0152] The determining unit is used to determine the vibration waveform of the scattering position using the backscattering phase of the scattering position.

[0153] Preferably, in some embodiments, the extraction unit 503 includes a beam splitting module, a first detection module, a second detection module, and an extraction module, and the execution principle of each module is as follows:

[0154] The beam splitting module is used to split the light emitted by the auxiliary light source into a first auxiliary light and a second auxiliary light.

[0155] The first detection module is used to coherently detect the first auxiliary light and the backscattered light to obtain the first radio frequency signal.

[0156] The second detection module is used to coherently detect the first reference light and the second auxiliary light to obtain the second radio frequency signal.

[0157] The extraction module is used to extract the backscatter phase at each scattering position in the optical fiber link based on the first radio frequency signal and the second radio frequency signal.

[0158] In some embodiments, the extraction module is specifically used to: orthogonalize the first radio frequency signal and the second radio frequency signal respectively to obtain a first orthogonal signal of the first radio frequency signal and a second orthogonal signal of the second radio frequency signal; use the delay duration corresponding to the scattering position i in the optical fiber link to time delay the second orthogonal signal, with the initial value of i being 0; perform transformation operations on the first orthogonal signal and the time-delayed second orthogonal signal to obtain a first digital signal sequence and a second digital signal sequence; extract the backscattering phase of the scattering position i based on the first digital signal sequence and the second digital signal sequence; increment i by 1, and return to execute the step of using the delay duration corresponding to the scattering position i in the optical fiber link to time delay the second orthogonal signal.

[0159] The specific implementation of the extraction module to obtain the first digital signal sequence and the second digital signal sequence is as follows: cross-multiply the first orthogonal signal and the second orthogonal signal after time delay, and add and subtract the cross-multiplication results respectively to obtain the first digital signal sequence and the second digital signal sequence.

[0160] The specific implementation method of the extraction module to extract the backscattering phase of scattering position i is as follows: the first digital signal sequence and the second digital signal sequence are subjected to moving average processing to obtain the moving average processing result corresponding to scattering position i; the moving average processing result corresponding to scattering position i is subjected to phase demodulation processing to extract the backscattering phase of scattering position i.

[0161] In summary, this invention provides a distributed optical fiber sensing method and apparatus based on the uncertainty principle. The light from a detection source is divided into a first detection light and a first reference light. The first detection light is incident on an optical fiber link to obtain the backscattered light of the optical fiber link. Based on the first reference light, the backscattered light, and an auxiliary light source, the backscattered phase at each scattering position in the optical fiber link is extracted, thereby achieving distributed sensing based on continuous backscattering, and ultimately realizing distributed optical fiber vibration sensing.

[0162] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and relevant parts can be referred to the descriptions in the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0163] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0164] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A distributed fiber-optic sensing method based on the principle of uncertainty, characterized in that, The method is based on the Heisenberg uncertainty principle and includes: The light emitted from the detection light source is divided into a first detection light and a first reference light; The first probe light is incident on the optical fiber link to obtain the backscattered light of the optical fiber link; Based on the first reference light, the backscattered light, and the auxiliary light source, the backscattered phase at each scattering position in the optical fiber link is extracted, and the backscattered phase is used to realize distributed optical fiber vibration sensing. Based on the first reference light, the backscattered light, and the auxiliary light source, the backscattered phase at each scattering position in the optical fiber link is extracted, including: The light emitted by the auxiliary light source is divided into first auxiliary light and second auxiliary light; The first auxiliary light and the backscattered light are coherently detected to obtain the first radio frequency signal; The first reference light and the second auxiliary light are coherently detected to obtain the second radio frequency signal; Based on the first radio frequency signal and the second radio frequency signal, the backscattering phase at each scattering position in the optical fiber link is extracted, wherein the extraction of the backscattering phase is based on the Heisenberg uncertainty principle.

2. The method according to claim 1, characterized in that, The detection light source is applicable to any laser light source.

3. The method according to claim 1, characterized in that, Based on the first radio frequency signal and the second radio frequency signal, the backscattering phase at each scattering location in the optical fiber link is extracted, including: The first radio frequency signal and the second radio frequency signal are orthogonalized respectively to obtain a first orthogonal signal of the first radio frequency signal and a second orthogonal signal of the second radio frequency signal; The second orthogonal signal is time-delayed using the delay duration corresponding to the scattering position i in the optical fiber link, with the initial value of i being 0; The first orthogonal signal and the second orthogonal signal after time delay are transformed to obtain a first digital signal sequence and a second digital signal sequence. Based on the first digital signal sequence and the second digital signal sequence, the backscattering phase at scattering position i is extracted; Increment i by 1, and return to the step of using the delay duration corresponding to the scattering position i in the optical fiber link to time delay the second orthogonal signal.

4. The method according to claim 3, characterized in that, Transformation operations are performed on the first orthogonal signal and the second orthogonal signal after time delay to obtain a first digital signal sequence and a second digital signal sequence, including: The first orthogonal signal and the second orthogonal signal after time delay are cross-multiplied, and the cross-multiplication results are added and subtracted respectively to obtain the first digital signal sequence and the second digital signal sequence.

5. The method according to claim 3, characterized in that, Based on the first digital signal sequence and the second digital signal sequence, the backscattering phase at the scattering position i is extracted, including: The first digital signal sequence and the second digital signal sequence are subjected to moving average processing to obtain the moving average processing result corresponding to the scattering position i; Phase demodulation processing is performed on the moving average processing result corresponding to the scattering position i to extract the backscattering phase of the scattering position i.

6. The method according to claim 1, characterized in that, The backscattered light is either backscattered Rayleigh light, backscattered Raman light, or backscattered Brillouin light.

7. The method according to claim 1, characterized in that, The linewidth of the auxiliary light source is smaller than that of the detection light source.

8. The method according to claim 1, characterized in that, After extracting the backscatter phase at each scattering location in the optical fiber link, the method further includes: The vibration waveform at the scattering location is determined using the backscattering phase at the scattering location.

9. A distributed optical fiber sensing device based on the uncertainty principle, characterized in that, The device is based on the Heisenberg uncertainty principle and includes: The beam splitting unit is used to split the light emitted by the detection light source into a first detection light and a first reference light; A transmission unit is used to incident the first probe light onto the optical fiber link to obtain the backscattered light of the optical fiber link; The extraction unit is used to extract the backscatter phase at each scattering position in the optical fiber link based on the first reference light, the backscattered light, and the auxiliary light source. The backscattered phase is used to realize distributed optical fiber vibration sensing. The extraction unit includes: The beam splitting module is used to split the light emitted by the auxiliary light source into a first auxiliary light and a second auxiliary light. The first detection module is used to coherently detect the first auxiliary light and the backscattered light to obtain a first radio frequency signal; The second detection module is used to coherently detect the first reference light and the second auxiliary light to obtain the second radio frequency signal; The extraction module is used to extract the backscattering phase at each scattering position in the optical fiber link based on the first radio frequency signal and the second radio frequency signal, wherein the extraction of the backscattering phase is based on the Heisenberg uncertainty principle.

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