Method and device for predicting time division crosstalk of fiber grating array

Abstract

The invention relates to the technical field of optical fiber sensing, in particular to a method and equipment for predicting time division crosstalk of a fiber grating array. The prediction method comprises the following steps: simulating a main pulse after laser is input into the fiber grating array; calculating the number of crosstalk pulses and a corresponding grating ordinal number when each crosstalk pulse is reflected according to the time division channel number of the fiber grating array; simulating a total crosstalk pulse according to the number of the crosstalk pulses and the corresponding reflection grating ordinal number when each crosstalk pulse is reflected; and calculating a total interference pulse according to the simulation results of the main pulse and the total crosstalk pulse, and extracting an interference signal from the total interference pulse and demodulating the interference signal. By considering the size and phase information of the main pulse and the crosstalk pulse, the crosstalk condition of the fiber array can be comprehensively predicted and evaluated, the crosstalk condition of the fiber grating array can be more accurately predicted, and the interference pulse, the interference signal and the demodulation result of each channel under the influence of crosstalk can be more detailedly displayed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical fiber sensing, in particular to a prediction method and device for time division crosstalk of a fiber grating array. BACKGROUND

[0002] The Fabry-Perot (F-P) type fiber Bragg grating (referred to as fiber grating) acoustic signal sensing system based on matched interference has the advantages of simple structure, easy large-scale multiplexing, high sensitivity, large dynamic range, etc., and is widely used in the field of underwater acoustic sensing. Although the fiber grating array is an ideal device in the field of underwater acoustic sensing, the fiber grating has both transmission and reflection effects on light, which causes multiple reflections of light signals in the F-P type fiber grating array, and crosstalk between array channels, which reduces the sensing performance of the array system. Generally speaking, the crosstalk between channels of a time division multiplexing array has the greatest impact on performance, because the center wavelengths of the fiber gratings in the time division multiplexing array are the same. Therefore, accurate estimation of the size of the crosstalk of the time division multiplexing fiber grating array is very important for array design.

[0003] In related technologies, the analysis of the crosstalk principle of the fiber grating F-P cavity type hydrophone mainly calculates the amplitudes of the main pulse and the crosstalk pulse according to the reflectivity R and the transmittance (1-R) of the fiber grating. However, the existing technology does not better consider the influence of the interference of the main pulse and the crosstalk pulse on the result, ignores the phase information, and only uses the amplitude of the interference signal in the worst case to evaluate the size of the crosstalk, resulting in errors in evaluation and results. In view of this, how to accurately predict the crosstalk of each channel of different fiber grating arrays is a technical problem to be solved in optimizing the design of fiber grating arrays. SUMMARY

[0004] In related technologies, the analysis and prediction of the time division crosstalk of the fiber grating array only uses the amplitude of the interference signal in the worst case to evaluate the size of the crosstalk, resulting in errors in evaluation and results.

[0005] In a first aspect, an embodiment of the present application provides a prediction method for time division crosstalk of a fiber grating array, the prediction method comprising: simulating a main pulse after laser input into the fiber grating array, the main pulse being a reflected pulse generated by the main pulse only experiencing reflection of the fiber grating once after the light pulse is incident on the fiber grating array and being transmitted to the first fiber grating and output from the array; calculating the number of crosstalk pulses and the corresponding grating order number when each crosstalk pulse is reflected according to the time division channel number of the fiber grating array; simulating the total crosstalk pulse according to the number of crosstalk pulses and the corresponding reflected grating order number when each crosstalk pulse is reflected; The total interference pulse is calculated according to the main pulse and the total crosstalk pulse simulation result, and an interference signal is extracted from the total interference pulse and the interference signal is demodulated.

[0006] In combination with the first aspect, in an implementation, the calculation of the number of crosstalk pulses and the corresponding grating sequence number of each crosstalk pulse being reflected according to the time division channel number of the fiber grating array comprises: According to the predicted order of the crosstalk pulse, the reflection times of the crosstalk pulse of the corresponding order in the fiber grating array are obtained. According to the time division channel number of the fiber grating array and the reflection times, the number of crosstalk pulses is calculated, and the corresponding grating of each crosstalk pulse being reflected is obtained.

[0007] In combination with the first aspect, in an implementation, the simulation of the total crosstalk pulse according to the number of crosstalk pulses and the corresponding reflection grating sequence number of each crosstalk pulse being reflected comprises: According to the corresponding grating sequence number of each crosstalk pulse being reflected, the reflection order of each crosstalk pulse is obtained. According to the reflection order, the reflection process between the gratings in the crosstalk pulse is simulated and calculated. All crosstalk pulse signals are added to obtain a total crosstalk pulse signal.

[0008] In combination with the first aspect, in an implementation, the simulation and calculation of the reflection process of the crosstalk pulse according to the corresponding reflection grating sequence number of each crosstalk pulse being reflected to obtain the reflection pulse result comprises: According to the corresponding reflection grating sequence number of each crosstalk pulse being reflected, the reflection order of each crosstalk pulse is obtained. According to the reflection order, the reflection process between the gratings in the crosstalk pulse is simulated and calculated.

[0009] In combination with the first aspect, in an implementation, the simulation and calculation of the reflection process between the gratings in the crosstalk pulse according to the reflection order comprises: The reflection process of the optical pulse after being transmitted from the first grating to the grating of the first sequence number in the reflection grating sequence number is simulated and calculated to obtain the first reflection pulse result. According to the first reflection pulse result and the reflection grating sequence number, the simulation and calculation of all reflection pulse results are sequentially completed.

[0010] In combination with the first aspect, in an implementation, the simulation and calculation of the reflection process of the optical pulse after being transmitted from the first grating to the grating of the first sequence number in the reflection grating sequence number to obtain the first reflection pulse result comprises: According to the formula:

[0011]

[0012] acquiring the first reflection pulse result , wherein r is a reflection coefficient, is a digital sampling rate, L is a fiber length between two adjacent gratings, c is a speed of light in vacuum, and n is an effective refractive index of the fiber, is an acoustic signal, is a transmitted light pulse of the first grating.

[0013] With reference to the first aspect, in an embodiment, the calculating the total interference pulse according to the main pulse and the total crosstalk pulse comprises: according to the formula:

[0014] acquiring the total interference pulse , wherein is a total crosstalk pulse signal, pulsesignalzt is a main pulse signal corresponding to the Z+1th fiber grating, pulsesignal0r is a main pulse corresponding to the first fiber grating, and a is a time division channel number of the fiber grating array.

[0015] With reference to the first aspect, in an embodiment, the extracting an interference signal from the total interference pulse and demodulating the interference signal comprises: according to the formula:

[0016] acquiring the interference signal of each time division channel , wherein TDM represents a time division channel, is a digital sampling rate, L is a fiber length between two adjacent gratings, c is a speed of light in vacuum, and n is an effective refractive index of the fiber, is a pulse sampling rate, and N is a sampling point.

[0017] With reference to the first aspect, in an embodiment, the simulating the main pulse after the laser input fiber grating array comprises: simulating a process of continuous laser output by a laser, input to the fiber grating array through an optical modulator and an interferometer according to preset simulation parameters, and calculating a result of a reflection pulse generated by each fiber grating after the first time receiving a light pulse and transmitted to the first fiber grating and output from the array.

[0018] In a second aspect, the embodiments of the present application provide a device for predicting time-domain crosstalk of a fiber grating array, which comprises a processor, a memory, and a prediction program stored in the memory and executable by the processor, wherein the prediction program, when executed by the processor, implements the steps of the method for predicting time-domain crosstalk of a fiber grating array according to any one of the preceding aspects.

[0019] The technical scheme provided by the embodiments of the present application has the following beneficial effects: The embodiments of the present application can comprehensively predict and evaluate the crosstalk of the fiber array by considering the size and phase information of the main pulse and the crosstalk pulse, thereby more accurately and comprehensively predicting the crosstalk of the fiber grating array and more detailedly displaying the interference pulse, interference signal, and demodulation result of each channel under the influence of crosstalk, further guiding the array design of the fiber grating. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 FIG. 1 is a flowchart of an embodiment of the method for predicting time-domain crosstalk of a fiber grating array according to the present application; Figure 2 FIG. 2 is a schematic diagram of the laser outputting laser light to the fiber grating array in an embodiment of the present application; Figure 3 FIG. 3 is a schematic diagram of the principle of the interferometer in an embodiment of the present application; Figure 4 FIG. 4 is a distance map of each crosstalk pulse transmission in an embodiment of the present application; Figure 5 FIG. 5 is a total interference pulse calculation result graph in an embodiment of the present application; Figure 6 FIG. 6 is a signal demodulation result graph of the first time division in an embodiment of the present application; Figure 7 FIG. 7 is a signal demodulation result graph of the second time division in an embodiment of the present application; Figure 8 FIG. 8 is a schematic diagram of a system modulated by the heterodyne method in an embodiment of the present application; Figure 9 FIG. 9 is a schematic diagram of the hardware structure of the device for predicting time-domain crosstalk of a fiber grating array involved in the embodiments of the present application. DETAILED DESCRIPTION

[0021] In order to enable persons skilled in the art to better understand the present application, the technical scheme in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by persons skilled in the art without creative labor fall within the scope of protection of the present application.

[0022] In the related art, the analysis and prediction of the time division crosstalk of the fiber grating array only uses the amplitude of the interference signal in the worst case to evaluate the crosstalk size, resulting in errors in evaluation and results.

[0023] In order to make the purpose, technical scheme and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the drawings.

[0024] In a first aspect, the embodiments of the present application provide a prediction method for time division crosstalk of a fiber grating array, the prediction method comprising: Step S1, simulating a main pulse after the laser input fiber grating array, the main pulse being a reflected pulse generated after the light pulse incident on the fiber grating array only experiences one reflection of the fiber grating, and the result of transmitting to the first fiber grating and transmitting output array.

[0025] In an optional embodiment of the present application, the process of the laser outputting laser to the fiber grating array is as shown in Figure 2 According to the preset simulation parameters, the process of the continuous laser output by the laser being input to the fiber grating array through the modulator and the interferometer is simulated, and the result of the reflected pulse generated by each fiber grating after the first reception of the light pulse transmitting to the first fiber grating and transmitting output array is calculated.

[0026] In this embodiment, the simulation process of the main pulse includes: Step S1a, setting the simulation parameters.

[0027] Specifically, the simulation parameters required to be set in the present embodiment taking PGC modulation as an example include: reflectivity R of the fiber grating; transmittance T = 1-R; reflection coefficient , transmittance coefficient , interferometer arm length difference and fiber grating interval (fiber length between two adjacent fiber gratings) L, characteristic frequency of the modulation method, acoustic signal frequency , digital sampling rate , pulse sampling rate (pulse modulation period) , pulse width .

[0028] In some optional embodiments, if it is heterodyne modulation as shown in Figure 8 . Step S1a, simulating the process of the laser to the acousto-optic modulator.

[0029] It should be noted that this process is the continuous laser output by the laser being modulated into periodic pulse light by the acousto-optic modulator.

[0030] First pulse light The expression is:

[0031] In the formula, is the pulse period, t is the transmission coefficient, is the pulse width.

[0032] Step S1b, simulate the process of pulsed light from the acousto-optic modulator to the interferometer.

[0033] It should be noted that the specific structure of the interferometer is as shown in Figure 3 The simulation process is that the modulated light pulses output by the acousto-optic modulator are divided into two light pulses by the 2*2 coupler, and are transmitted through the reference arm and the signal arm respectively and reflected by the Faraday rotator mirror. The reference arm and the signal arm are different in length and are wound on the PZT, and the difference in arm length will cause the transmission time of the two light pulses to be different, and the two arms can modulate different signals. In this example, the carrier wave is modulated on the signal arm, and the reference sound signal is selectively modulated on the reference arm. Finally, the reverse passes through the 2*2 coupler to become a double light pulse composed of two light pulses with time delay.

[0034] Further, the two second light pulses , are expressed as:

[0035] In the formula, is the first pulsed light signal.

[0036] The light pulse passing through the reference arm is modulated by the reference sound signal and expressed as:

[0037]

[0038] In the formula, is the reference sound signal, is the reference sound signal frequency, and the light pulse passing through the sensing arm is modulated by the carrier wave and expressed as:

[0039] In the formula, is the time delay caused by the difference in arm length in the round-trip transmission of light, c is the speed of light in vacuum, and n is the effective refractive index of the optical fiber. After passing through the coupler, the two pulses are combined into one, which is the third pulse output by the interferometer:

[0040] It should be noted that, as Figure 2The function of the circulator is to ensure the order of the light transmission. The circulator can make the light output from the interferometer inject into the fiber grating array, and the light reflected from the fiber grating enter the data collector. Figure 2 In the embodiment, the fiber grating array is an 8-time division multiplexing array, which is composed of 9 fiber gratings. Each adjacent two fiber gratings form a sensing element.

[0041] Step S1c, simulating the main pulse signal reflected after the pulse output from the interferometer injects into the fiber grating.

[0042] Specifically, the application provides a specific embodiment of an 8-time division multiplexing array, and step S1c includes: Step A, the first fiber grating reflects and transmits the light pulse at the same time.

[0043] The reflected light of the first fiber grating And the transmitted light pulse Is expressed as:

[0044] It should be noted that the above-mentioned first fiber grating refers to the first injected fiber grating after the light pulse injects into the fiber grating array.

[0045] Step B, the transmitted light passes through a certain length of optical fiber and is delayed and modulated by the acoustic signal, which is expressed as:

[0046] Wherein, is the pulse transmitted from the first fiber grating to the second fiber grating, and after encountering the second fiber grating, reflection and transmission occur again, which are expressed as:

[0047] Step C, the reflected light of the second fiber grating passes through a certain length of optical fiber again and is delayed and modulated by the acoustic signal, which is expressed as:

[0048] In the formula, refers to the pulse transmitted from the second fiber grating to the first fiber grating after reflection, and after encountering the first fiber grating again, reflection and transmission occur again, which are expressed as:

[0049] Step D, the transmitted light of the second fiber grating repeats the above delay, acoustic signal modulation and transmission and reflection of the next fiber grating, and so on. The results of the reflected pulse of each fiber grating transmitted to the first fiber grating and transmitted out of the array are calculated, respectively, , , , , , , , , That is, the main pulse reflected by the fiber grating.

[0050] Step S2: Calculate the number of crosstalk pulses and the grating sequence number corresponding to each crosstalk pulse when it is reflected, based on the number of time-division channels of the fiber grating array.

[0051] The above step S2 specifically includes: Step S2a: Obtain the number of reflections of the crosstalk pulse of the corresponding order in the fiber grating array based on the predicted crosstalk pulse order.

[0052] Specifically, if the target signal to be predicted is a first-order crosstalk pulse, then the first-order crosstalk pulse will be reflected three times in a fiber optic grating array.

[0053] Step S2b: Calculate the number of crosstalk pulses based on the number of time-division channels and the number of reflections of the fiber grating array, and obtain the grating corresponding to each crosstalk pulse when it is reflected.

[0054] In some alternative embodiments, taking a fiber Bragg grating array with 8 time-division channels as an example, there are 9 fiber Bragg gratings. The first reflection of the optical pulse will occur at any of the 2nd to 9th gratings, assuming the grating where the first reflection occurs is the i-th grating, i=2:1:9; the second reflection will occur at one of the 1st to (i-1th)th gratings, assuming the grating where the second reflection occurs is the j-th grating, j=1:1:i-1; the third reflection will occur at one of the (j+1th)th to 9th gratings, assuming the grating where the third reflection occurs is the k-th grating, k=j+1:1:9.

[0055] Understandably, knowing the time-minute fraction of the array allows us to calculate the number of crosstalk pulses and the corresponding grating number (i, j, k) for each crosstalk pulse. (See attached...) Figure 2 The 8-time-division grating array shown can be simulated to have a total of 204 crosstalk pulses and their corresponding 204 sets of grating numbers: i, j, k.

[0056] Furthermore, the transmission distance of each crosstalk pulse is shown in the attached figure. Figure 4 As shown, the red line represents the maximum transmission distance of the main pulse, and the yellow line represents the minimum transmission distance of the next cycle. Crosstalk pulses with a transmission distance below the red line affect the signal of the current cycle. Crosstalk between the red and yellow lines has no effect on the signal, while crosstalk pulses above the yellow line affect the signal of the next cycle. The 8-time-division array used in this example will not have crosstalk between cycles, but arrays with more time divisions will have this problem.

[0057] Step S3, simulate the total crosstalk pulses according to the number of crosstalk pulses and the corresponding reflection grating number when each crosstalk pulse is reflected.

[0058] The step S3 specifically includes: Step S3a, simulate the reflection process of the crosstalk pulses according to the corresponding grating number when each crosstalk pulse is reflected to obtain the reflection pulse result.

[0059] Specifically, the crosstalk pulse can be simulated according to the grating number corresponding to each reflection of the crosstalk pulse.

[0060] In some specific embodiments, the step S3a includes: Step A, obtain the reflection order in each crosstalk pulse according to the corresponding reflection grating number when each crosstalk pulse is reflected.

[0061] Specifically, taking the specific embodiment listed in step S2 as an example: the grating corresponding to three reflections of a crosstalk pulse, such as the grating number i, j, k corresponding to the first crosstalk pulse is 2, 1, 2 in turn.

[0062] Step B, simulate the reflection process between the gratings in the crosstalk pulse according to the reflection order.

[0063] Specifically, the reflection process of the light pulse after being transmitted from the first grating to the grating corresponding to the first reflection grating number is simulated to obtain the first reflection pulse result: first simulate the process of the light pulse being transmitted from the first grating to the second grating, and the first reflection pulse after being reflected after being transmitted to the second grating is represented as:

[0064]

[0065] In the formula, is the transmitted light pulse of the first grating. r is the reflection coefficient, is the digital sampling rate, L is the optical fiber length between two adjacent gratings, c is the speed of light in vacuum, and n is the effective refractive index of the optical fiber, is the acoustic signal.

[0066] According to the first reflection pulse result and the simulation calculation of all reflection pulse results in turn completed by the reflection grating number: The reflected pulse is transmitted back to the first grating to form a second reflection pulse represented as:

[0067]

[0068] Further, the second reflected pulse is transmitted to the second grating through the optical fiber, and the third reflected pulse formed by the reflection is represented as:

[0069]

[0070] Step S3b, according to the reflection pulse result, the transmission to the first grating and the transmission of each crosstalk pulse are simulated to obtain the corresponding crosstalk pulse signal; Specifically, according to the above embodiment, when the third pulse is transmitted to the first grating and the transmission occurs, it is this crosstalk pulse, which is represented as:

[0071]

[0072] Step S3c, all the crosstalk pulse signals are added to obtain the total crosstalk pulse signal.

[0073] The total crosstalk pulse signal is represented as:

[0074] In the formula, m is the total number of crosstalk pulses corresponding to one grating calculated in step S2.

[0075] Step S4, the total interference pulse is calculated according to the simulation results of the main pulse and the total crosstalk pulse. Specifically, according to the formula:

[0076] The total interference pulse is obtained , in which, is the total crosstalk pulse signal, is the main pulse signal corresponding to the Z+1th optical fiber grating, is the main pulse corresponding to the first optical fiber grating, and a is the time division channel number of the optical fiber grating array. Further, the pulse calculation result is shown in FIG. 6, in which the yellow color represents the power size of the total interference pulse, and the red and blue colors represent the amplitude and power size of the crosstalk pulse, respectively. Figure 5

[0077] Step S5, the interference signal is extracted from the total interference pulse, and the interference signal is demodulated.

[0078] Suppose the number of gratings is , then the array has time division channels, and TDM represents the channel, 0<TDM< ​The signal of each time division channel is:

[0079] The interference signal of each time division channel is acquired , wherein TDM represents the time division channel, is the digital sampling rate, L is the fiber length between two adjacent gratings, c is the speed of light in vacuum, and n is the effective refractive index of the fiber, is the pulse sampling rate, and N is the sampling point. According to the modulation method used in this example, the PGC demodulation algorithm is used for demodulation.

[0080] In some specific embodiments, when the reflectivity is 0.1, the arm length difference is 20 m, the acoustic signal amplitude is 1 rad, and the frequency is 400 Hz, only after the signal is added to the first time division, the signal demodulation results of the first and second time divisions are as shown in FIGS. 8A and 8B. Figure 6 、 7

[0081] In a second aspect, the embodiments of the present application provide a fiber grating array time division crosstalk prediction device. The fiber grating array time division crosstalk prediction device can be a personal computer (PC), a notebook computer, a server, or other device with data processing function.

[0082] Referring to Figure 9 , Figure 9 FIG. 1 is a hardware structure schematic diagram of a fiber grating array time division crosstalk prediction device involved in the embodiments of the present application. In the embodiments of the present application, the fiber grating array time division crosstalk prediction device can include a processor, a memory, a communication interface, and a communication bus.

[0083] The communication bus can be of any type, used to realize the interconnection of the processor, the memory, and the communication interface.

[0084] The communication interface includes an input / output (I / O) interface, a physical interface, and a logical interface, and other interfaces used to realize the interconnection of devices inside the fiber grating array time division crosstalk prediction device, and interfaces used to realize the interconnection of the fiber grating array time division crosstalk prediction device and other devices (such as other computing devices or user devices). The physical interface can be an Ethernet interface, a fiber interface, an ATM interface, etc.; the user device can be a display (Display), a keyboard (Keyboard), etc.

[0085] ​The memory can be various types of storage media such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), flash memory, optical storage, hard disk, programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), and the like.

[0086] The processor can be a general-purpose processor, which can invoke a prediction program of time division crosstalk of a fiber grating array stored in the memory and execute the prediction method of time division crosstalk of the fiber grating array provided in the embodiments of the present application. For example, the general-purpose processor can be a central processing unit (CPU). The method executed when the prediction program of time division crosstalk of the fiber grating array is invoked can refer to various embodiments of the prediction method of time division crosstalk of the fiber grating array of the present application, which will not be described here.

[0087] Those skilled in the art can understand that Figure 9 The hardware structure shown in the above-mentioned embodiments is not a limitation of the present application, and can include more or fewer components than those shown, or combine certain components, or different arrangement of components.

[0088] In a fourth aspect, the embodiments of the present application further provide a computer readable storage medium.

[0089] The computer readable storage medium of the present application stores a prediction program of time division crosstalk of a fiber grating array, wherein when the prediction program of time division crosstalk of the fiber grating array is executed by a processor, the steps of the prediction method of time division crosstalk of the fiber grating array as described above are implemented.

[0090] The method implemented when the prediction program of time division crosstalk of the fiber grating array is executed can refer to various embodiments of the prediction method of time division crosstalk of the fiber grating array of the present application, which will not be described here.

[0091] In summary, the present application can comprehensively predict and evaluate the crosstalk of the fiber array by considering the size and phase information of the main pulse and the crosstalk pulse, thereby more accurately and comprehensively predicting the crosstalk of the fiber grating array, and more detailedly displaying the interference pulse, interference signal, demodulation result of each channel under the influence of crosstalk, and further guiding the array design of the fiber grating.

[0092] It should be noted that the above-mentioned sequence numbers of the embodiments of the present application are only for description, and do not represent the advantages and disadvantages of the embodiments.

[0093] The terms "include," "includes" or "including," and any variations thereof, in the DETAILED DESCRIPTION of the Invention and the claims herein, and throughout the above description, are intended to cover both express and implied referencing. For example, a process, method, system, product, or apparatus that comprises a list of steps or elements is not necessarily limited to those listed steps or elements but can include other not-listed steps or elements, or can include other steps or elements that are inherent to such process, method, system, product, or apparatus. The terms "first," "second," and "third," and the like, are used merely to distinguish one element from another and are not meant to denote a first, second, and third order, or priority.

[0094] In the description of the embodiments of the present application, "exemplary," "for example," or "e.g." is used to represent an example, an illustration, or an example of the present application. Any embodiment or design scheme described as "exemplary," "for example," or "e.g." in the embodiments of the present application should not be interpreted as being more preferred or superior to other embodiments or design schemes. In fact, the words "exemplary," "for example," or "e.g." are used to present the relevant concept in a specific manner.

[0095] In the description of the embodiments of the present application, unless otherwise specified, " / " means or, for example, A / B can mean A or B; "and / or" in the text only represents a description of the relationship between the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, in the description of the embodiments of the present application, "multiple" means two or more than two.

[0096] In some of the processes described in the embodiments of the present application, a plurality of operations or steps are included in a specific order, but it should be understood that these operations or steps can be executed or performed in parallel or in an order different from that in which they appear in the embodiments of the present application. The serial number of the operation is only used to distinguish different operations, and the serial number itself does not represent any execution order. In addition, these processes can include more or fewer operations, and these operations or steps can be executed or performed in sequence or in parallel, and these operations or steps can be combined.

[0097] Those skilled in the art can clearly understand the above-mentioned embodiment method can be realized by means of software and the necessary general hardware platform, of course, can also be realized by hardware, but in many cases, the former is a better embodiment. Based on such understanding, the technical solutions of the present application can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes a plurality of instructions for making a terminal device execute the method described in each embodiment of the present application.

[0098] The above is only the preferred embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent process transformation using the content of the specification and drawings, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for predicting time-division crosstalk in a fiber optic grating array, characterized in that, The prediction method includes: The simulation is performed on the main pulse after the laser is input into the fiber Bragg grating array. The main pulse is the result of the optical pulse entering the fiber Bragg grating array, undergoing only one reflection of the fiber Bragg grating, being transmitted to the first fiber Bragg grating, and then being transmitted and output to the array. The number of crosstalk pulses and the grating sequence number corresponding to each crosstalk pulse when it is reflected are calculated based on the number of time-division channels in the fiber grating array. The total crosstalk pulses are simulated based on the number of crosstalk pulses and the number of the reflection grating corresponding to each crosstalk pulse when it is reflected. The total interference pulse is calculated based on the simulation results of the main pulse and the total crosstalk pulse, and the interference signal is extracted from the total interference pulse and demodulated.

2. The method for predicting time-division crosstalk in a fiber optic grating array as described in claim 1, characterized in that, The calculation of the number of crosstalk pulses and the grating sequence number corresponding to the reflection of each crosstalk pulse based on the time-division channel number of the fiber grating array includes: The number of reflections of the crosstalk pulse of the corresponding order in the fiber grating array is obtained based on the predicted crosstalk pulse order. The number of crosstalk pulses is calculated based on the number of time-division channels and the number of reflections of the fiber grating array, and the grating corresponding to each crosstalk pulse when it is reflected is obtained.

3. The method for predicting time-division crosstalk in a fiber optic grating array as described in claim 1, characterized in that, The simulation of the total crosstalk pulses based on the number of crosstalk pulses and the corresponding grating number when each crosstalk pulse is reflected includes: The reflection process of the crosstalk pulse is simulated and calculated based on the grating number corresponding to each crosstalk pulse when it is reflected to obtain the reflection pulse results; Based on the reflected pulse results, the process of each crosstalk pulse being transmitted to the first fiber grating and then transmitted is simulated and calculated to obtain the corresponding crosstalk pulse signal. The total crosstalk pulse signal is obtained by summing all the crosstalk pulse signals.

4. The method for predicting time-division crosstalk in a fiber optic grating array as described in claim 3, characterized in that, The step of simulating and calculating the reflection process of crosstalk pulses based on the reflection grating ordinal number corresponding to each crosstalk pulse being reflected to obtain the reflection pulse results includes: The reflection order in each crosstalk pulse is obtained by determining the reflection grating number corresponding to each crosstalk pulse when it is reflected. The reflection process between gratings in a crosstalk pulse is simulated and calculated according to the reflection sequence.

5. The method for predicting time-division crosstalk in a fiber optic grating array as described in claim 4, characterized in that, The simulation calculation of the reflection process between gratings in the crosstalk pulse according to the reflection sequence includes: The process of light pulse being transmitted from the first grating to the first ordinal grating in the reflection grating sequence is simulated and calculated to obtain the result of the first reflection pulse. The simulation calculations for all reflection pulse results are completed sequentially based on the first reflection pulse result and the reflection grating sequence.

6. The method for predicting time-division crosstalk in a fiber optic grating array as described in claim 5, characterized in that, The simulation calculation of the process of the light pulse being transmitted from the first grating to the first ordinal grating in the reflection grating sequence to obtain the result of the first reflection pulse includes: According to the formula: Obtain the result of the first reflected pulse In the formula, r is the reflection coefficient. Where is the digital sampling rate, L is the fiber length between two adjacent gratings, c is the speed of light in a vacuum, and n is the effective refractive index of the fiber. For sound signals, This is the transmitted light pulse for the first grating.

7. The method for predicting time-division crosstalk in a fiber optic grating array as described in claim 1, characterized in that, The calculation of the total interference pulse based on the main pulse and the total crosstalk pulse includes: According to the formula: Obtain the total interference pulse In the formula, For total crosstalk pulse signal, This is the main pulse signal corresponding to the (Z+1)th fiber grating. It is the main pulse signal corresponding to the first fiber Bragg grating, and 'a' is the time-division channel number of the fiber Bragg grating array.

8. The method for predicting time-division crosstalk in a fiber optic grating array as described in claim 1, characterized in that, The step of extracting the interference signal from the total interference pulse and demodulating the interference signal includes: According to the formula: Acquire the interference signal for each time-division channel In the formula, TDM represents time-division channel. Where is the digital sampling rate, L is the fiber length between two adjacent gratings, c is the speed of light in a vacuum, and n is the effective refractive index of the fiber. Where is the pulse sampling rate, and N is the number of sampling points.

9. The method for predicting time-division crosstalk in a fiber optic grating array as described in claim 1, characterized in that, The simulation of the main pulse after the laser is input into the fiber grating array includes: The simulation was performed based on preset simulation parameters to simulate the process of continuous laser output from the laser being input into the fiber grating array via an optical modulator and interferometer. The result was calculated that the reflected pulse generated by each fiber grating after receiving the first optical pulse was transmitted to the first fiber grating and then transmitted to the output array.

10. A device for predicting time-division crosstalk in a fiber Bragg grating array, characterized in that, The prediction device includes a processor, a memory, and a prediction program stored in the memory and executable by the processor, wherein when the prediction program is executed by the processor, it implements the steps of the prediction method for time-division crosstalk of a fiber Bragg grating array as described in any one of claims 1 to 9.

Images