Insertion loss measurement method in optical fiber isolators

Abstract

The present invention provides a method for measuring insertion loss in an optical fiber isolator. The method comprises: detecting a first measurement signal corresponding to a measurement branch, a first reference signal corresponding to a reference branch, and a first calibration signal corresponding to a calibration branch; determining an initial insertion loss value of the optical fiber isolator based on the first measurement signal and the first reference signal; determining a connection compensation parameter of the optical fiber isolator based on the first reference signal and the first calibration signal; obtaining an optical path compensation parameter, and compensating the initial insertion loss value based on the optical path compensation parameter and the connection compensation parameter to obtain the insertion loss in the optical fiber isolator. The present invention monitors the light source signal in real time through the reference branch, provides a reference signal with no device plug-in interference and a stable optical path state through the calibration branch, and synergistically compensates the initial insertion loss value by taking into account the connection compensation parameter and the optical path compensation parameter, thereby improving the measurement accuracy of the insertion loss of the optical fiber isolator.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber communication, and in particular to a method for measuring insertion loss in an optical fiber isolator. Background Art

[0002] In optical fiber communication systems, optical fiber isolators are key passive components. Their core function is to allow unidirectional transmission of optical signals and effectively suppress reverse reflected light, protecting lasers and other light sources from damage. The insertion loss of an optical fiber isolator is a key indicator of its performance. It directly reflects the degree of attenuation of the forward optical signal by the device, and its measurement accuracy is crucial. Traditional measurement methods usually use the ratio between the input signal and the output signal of the optical fiber isolator for measurement. Specifically, the optical signal emitted by the light source (input signal P in ) is connected to the input end of the optical fiber isolator, and the transmitted light signal (output signal P out ) is usually calculated using the following ratio formula: IL = -10 * log 10 (P out / P in However, in practical engineering applications, especially in scenarios with strict precision requirements (such as production testing and quality control), the power instability of the light source itself and the multidirectionality of reflections in the optical path can directly affect measurement accuracy. Therefore, a method for measuring the insertion loss of optical fiber isolators that can improve measurement accuracy is urgently needed. Summary of the Invention

[0003] The present invention provides a method for measuring insertion loss in an optical fiber isolator, aiming to provide a method for measuring insertion loss in an optical fiber isolator that can improve measurement accuracy. By adopting a three-optical path structure comprising a measurement branch, a reference branch, and a calibration branch, and synchronously detecting a first measurement signal, a first reference signal, and a first calibration signal, the method improves the measurement accuracy of the insertion loss of the optical fiber isolator by using the reference branch to monitor the light source signal in real time and providing a reference signal with no device plug-in interference and a stable optical path state through the calibration branch. Furthermore, the method also considers connection compensation parameters and optical path compensation parameters to collaboratively compensate for the initial insertion loss value.

[0004] In a first aspect, the present invention provides a method for measuring insertion loss in an optical fiber isolator. The optical fiber isolator is disposed on a measurement branch branched out by an optical fiber splitter. The optical fiber splitter further branches out a reference branch and a calibration branch. A target light source transmits a modulated optical signal, which enters the measurement branch, the reference branch, and the calibration branch respectively through the optical fiber splitter. The method comprises the following steps:

[0005] detecting a first measurement signal corresponding to the measurement branch, a first reference signal corresponding to the reference branch, and a first calibration signal corresponding to the calibration branch;

[0006] determining an initial insertion loss value of the optical fiber isolator based on the first measurement signal and the first reference signal;

[0007] determining a connection compensation parameter of the optical fiber isolator according to the first reference signal and the first calibration signal;

[0008] An optical path compensation parameter is obtained, and based on the optical path compensation parameter and the connection compensation parameter, the initial insertion loss value is compensated to obtain an insertion loss in the optical fiber isolator.

[0009] Optionally, a polarization controller is provided on the measurement branch, and the polarization controller is provided before the optical fiber isolator. Before the step of detecting the first measurement signal corresponding to the measurement branch, the first reference signal corresponding to the reference branch, and the first calibration signal corresponding to the calibration branch, the method further includes:

[0010] When the optical fiber isolator is in an unloaded state, installing a refractive index matching cap on the detection port of the measurement branch;

[0011] In the case of different refractive indices, the polarization controller is used to perform a gait scan over a preset range of angles at a preset step angle;

[0012] In each gait, the second measurement signal corresponding to the measurement branch, the second reference signal corresponding to the reference branch, and the second calibration signal corresponding to the calibration branch are synchronously sampled.

[0013] Optionally, the step of determining the initial insertion loss value of the optical fiber isolator based on the first measurement signal and the first reference signal specifically includes:

[0014] When the optical fiber isolator is in an unloaded state, determining a splitting ratio parameter of the optical fiber splitter;

[0015] Determining a first splitting ratio and a second splitting ratio corresponding to the measurement branch and the reference branch by using a splitting ratio parameter of the optical fiber splitter;

[0016] determining an adjustment coefficient based on the first splitting ratio and the second splitting ratio;

[0017] A weighted calculation is performed on the ratio of the first measurement signal to the first reference signal according to the adjustment coefficient to obtain an initial insertion loss value of the optical fiber isolator.

[0018] Optionally, the step of determining a connection compensation parameter of the optical fiber isolator according to the first reference signal and the first calibration signal specifically includes:

[0019] calculating a no-load loss deviation based on the second measurement signal and the second reference signal;

[0020] predicting a loaded loss deviation based on the no-load loss deviation and the first measurement signal;

[0021] Based on the actual load loss deviation, a connection compensation parameter of the optical fiber isolator is determined.

[0022] Optionally, the optical path compensation parameter includes a polarization compensation parameter, and the step of obtaining the optical path compensation parameter specifically includes:

[0023] determining, according to the second measurement signal of each gait, a first signal sequence corresponding to the second measurement signal;

[0024] determining, according to the second reference signal of each gait, a second signal sequence corresponding to the second reference signal;

[0025] determining, based on the second calibration signal of each gait, a third signal sequence corresponding to the second calibration signal;

[0026] Polarization compensation parameters are determined based on the first signal sequence, the second signal sequence, the third signal sequence, and the overall optical path diagram.

[0027] Optionally, determining a polarization compensation parameter based on the first signal sequence, the second signal sequence, the third signal sequence, and the overall optical path diagram includes:

[0028] Obtaining a training data set and a spatiotemporal convolution model to be trained, wherein the training data set includes quadruple sample data and polarization compensation parameter annotation data corresponding to the quadruple sample data, the quadruple sample data including a first signal sequence sample, a second signal sequence sample, a third signal sequence sample, and an overall optical path diagram sample, the input of the spatiotemporal convolution model to be trained is the quadruple sample data, and the output is polarization compensation parameter prediction data;

[0029] Training the to-be-trained spatiotemporal convolutional model using the training data set, and obtaining a trained spatiotemporal convolutional model after the training is completed;

[0030] The first signal sequence, the second signal sequence, the third signal sequence and the overall optical path diagram are processed by the trained spatiotemporal convolution model to determine polarization compensation parameters.

[0031] Optionally, the optical path compensation parameter further includes a temperature compensation parameter, and the step of obtaining the optical path compensation parameter further includes:

[0032] collecting the temperature value of the optical fiber splitter body in real time;

[0033] determining a splitting ratio drift compensation coefficient according to the temperature value;

[0034] The temperature compensation parameter is determined based on the splitting ratio drift compensation coefficient and a preset reference temperature.

[0035] Optionally, the step of determining the splitting ratio drift compensation coefficient according to the temperature value specifically includes:

[0036] Obtain a pre-calibrated temperature-splitting ratio drift curve;

[0037] querying the temperature-splitting ratio drift relationship curve according to the temperature value to obtain the splitting ratio drift amount corresponding to the temperature value;

[0038] The splitting ratio drift compensation coefficient is calculated based on the ratio of the splitting ratio drift to the splitting ratio at a reference temperature.

[0039] Optionally, the step of obtaining a pre-calibrated temperature-splitting ratio drift relationship curve specifically includes:

[0040] placing the optical fiber splitter in a temperature-controlled environment while the target light source transmits a modulated optical signal;

[0041] Adjusting the temperature within a preset temperature range with a preset temperature step size, and synchronously collecting a third reference signal value corresponding to the reference branch and a third calibration signal value corresponding to the calibration branch after each temperature point stabilizes;

[0042] Based on the third reference signal value and the third calibration signal value, the splitting ratio drift at each temperature point is calculated, and a polynomial fitting is performed on the splitting ratio drift at each temperature point to generate the temperature-splitting ratio drift relationship curve.

[0043] Optionally, the step of compensating the initial insertion loss value based on the optical path compensation parameter and the connection compensation parameter to obtain the insertion loss in the optical fiber isolator specifically includes:

[0044] The initial insertion loss value is compensated based on the connection compensation parameter, the polarization compensation parameter, and the temperature compensation parameter to obtain the insertion loss in the optical fiber isolator.

[0045] The present invention detects a first measurement signal corresponding to the measurement branch, a first reference signal corresponding to the reference branch, and a first calibration signal corresponding to the calibration branch; determines an initial insertion loss value of the optical fiber isolator based on the first measurement signal and the first reference signal; determines a connection compensation parameter of the optical fiber isolator based on the first reference signal and the first calibration signal; obtains an optical path compensation parameter, and compensates for the initial insertion loss value based on the optical path compensation parameter and the connection compensation parameter to obtain the insertion loss in the optical fiber isolator. The present invention adopts a three-optical path structure comprising a measurement branch, a reference branch, and a calibration branch of an optical fiber isolator, and synchronously detects the first measurement signal, the first reference signal, and the first calibration signal. The reference branch monitors the light source signal in real time, the calibration branch provides a reference signal with no device plug-in interference and a stable optical path state, and considers the connection compensation parameter and the optical path compensation parameter to collaboratively compensate for the initial insertion loss value, thereby improving the measurement accuracy of the insertion loss of the optical fiber isolator. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0047] Figure 1 This is a flow chart of a method for measuring insertion loss in an optical fiber isolator provided by an embodiment of the present invention;

[0048] Figure 2 This is a supplementary flow chart of a method for measuring insertion loss in an optical fiber isolator provided in an embodiment of the present invention;

[0049] Figure 3 is a specific flow chart of step S2 provided in an embodiment of the present invention;

[0050] Figure 4 is a specific flow chart of step S3 provided in an embodiment of the present invention;

[0051] Figure 5 is a specific flow chart of step S4 provided in an embodiment of the present invention;

[0052] Figure 6 is a specific flow chart of step S44 provided in an embodiment of the present invention;

[0053] Figure 7 is a supplementary flow chart of step S4 provided in an embodiment of the present invention;

[0054] Figure 8It is a specific flow chart of step S47 provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0055] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0056] like Figure 1 As shown, Figure 1 This is a flow chart of a method for measuring insertion loss in an optical fiber isolator provided by an embodiment of the present invention. The optical fiber isolator is arranged on a measurement branch branched out by an optical fiber splitter. The optical fiber splitter also branches out a reference branch and a calibration branch. A target light source transmits a modulated optical signal, which enters the measurement branch, reference branch, and calibration branch respectively through the optical fiber splitter. The insertion loss measurement method in the optical fiber isolator includes the following steps:

[0057] S1, detecting a first measurement signal corresponding to the measurement branch, a first reference signal corresponding to the reference branch, and a first calibration signal corresponding to the calibration branch.

[0058] S2: Determine an initial insertion loss value of the optical fiber isolator based on the first measurement signal and the first reference signal.

[0059] S3: Determine a connection compensation parameter of the optical fiber isolator according to the first reference signal and the first calibration signal.

[0060] S4, obtaining optical path compensation parameters, and compensating the initial insertion loss value based on the optical path compensation parameters and the connection compensation parameters to obtain the insertion loss in the optical fiber isolator.

[0061] In the embodiment of the present invention, the optical fiber isolator is an optical device that allows unidirectional transmission of optical signals and is used to suppress reverse reflected light. Its core performance indicator is insertion loss (optical power attenuation value in forward transmission).

[0062] A fiber optic splitter is an optical device used to distribute input optical signals to multiple output ports in a fixed ratio. In this embodiment, a 1×3 splitter is used, which splits the optical signals into three paths: a measurement path, a reference path, and a calibration path. The measurement path connects to the optical fiber isolator under test; the reference path directly transmits the optical source signal and can be used to monitor the light source's status; and the calibration path provides a stable reference path without plugging or unplugging components. Each path is terminated by a photodetector that converts the optical signal into an electrical signal. This electrical signal is then converted to a digital signal by an analog-to-digital converter for digital processing by a processor.

[0063] The target light source is a light source for emitting an amplitude / frequency modulated optical signal, and may be a laser diode or an infrared light emitter. The modulation method ensures that the signal can be synchronously detected. The modulation method may be to modulate the signal into a periodic signal, such as a cosine wave signal.

[0064] The first measurement signal is an electrical signal converted from the optical signal output by the fiber isolator in the measurement branch. The first reference signal is an electrical signal converted from the optical signal in the reference branch and is used to represent the real-time power of the light source. The first calibration signal is an electrical signal converted from the optical signal in the calibration branch and is used to provide an undisturbed reference. These electrical signals can be used to represent optical power, and different electrical signals can correspond to different optical powers through a lookup table.

[0065] The initial insertion loss value is the uncompensated loss value calculated by the measured signal and the reference signal. The calculation formula is:

[0066] ;

[0067] Among them, IL initial is the initial insertion loss value, P meas and P ref are the optical powers corresponding to the first measurement signal and the first reference signal respectively.

[0068] The connection compensation parameter is used to quantify the random loss introduced by plugging and unplugging, and can be determined using a reference signal and a calibration signal. In a possible embodiment, the connection compensation parameter can also be determined based on the number of plugging and unplugging cycles. The higher the number of plugging and unplugging cycles, the larger the connection compensation parameter.

[0069] The optical path compensation parameter may be a pre-calibrated dynamic loss between each branch.

[0070] Specifically, the target light source emits a modulated optical signal, which is distributed to three branches via a fiber optic splitter. The signal is synchronously collected by photodetectors. The photodetector at the output end of the measurement branch detects a first measurement signal; the photodetector at the output end of the reference branch detects a first reference signal; and the photodetector at the output end of the calibration branch detects a first calibration signal.

[0071] After obtaining the first measurement signal and the first reference signal, the initial insertion loss value can be calculated using the above formula. The initial insertion loss value includes the actual isolator loss, connector random loss, and optical path dynamic loss. Therefore, it is considered to compensate the initial insertion loss value by connecting the compensation parameters and the optical path compensation parameters to obtain a more accurate insertion loss value.

[0072] In an embodiment of the present invention, a first measurement signal corresponding to the measurement branch, a first reference signal corresponding to the reference branch, and a first calibration signal corresponding to the calibration branch are detected; an initial insertion loss value of the optical fiber isolator is determined based on the first measurement signal and the first reference signal; a connection compensation parameter of the optical fiber isolator is determined based on the first reference signal and the first calibration signal; an optical path compensation parameter is obtained, and the initial insertion loss value is compensated based on the optical path compensation parameter and the connection compensation parameter to obtain the insertion loss in the optical fiber isolator. The present invention adopts a three-optical path structure comprising a measurement branch, a reference branch, and a calibration branch of an optical fiber isolator, and synchronously detects the first measurement signal, the first reference signal, and the first calibration signal. The reference branch monitors the light source signal in real time, the calibration branch provides a reference signal with no device plug-in interference and a stable optical path state, and the initial insertion loss value is collaboratively compensated for by taking into account the connection compensation parameter and the optical path compensation parameter, thereby improving the measurement accuracy of the insertion loss of the optical fiber isolator.

[0073] It is understandable that in the specific implementation of this application, measurement data, equipment data and other related data are involved. When the embodiments in this application are applied to specific products or technologies, user permission or consent is required, and the collection, use and processing of relevant data, as well as the training, deployment and calling of algorithm models, must comply with the relevant laws, regulations and standards of relevant countries and regions.

[0074] Optionally, a polarization controller is provided on the measurement branch, and the polarization controller is provided before the optical fiber isolator, and before the step of detecting the first measurement signal corresponding to the measurement branch, the first reference signal corresponding to the reference branch, and the first calibration signal corresponding to the calibration branch, as follows: Figure 2 As shown, the method further includes:

[0075] S5. When the optical fiber isolator is in an unloaded state, install a refractive index matching cap on the detection port of the measurement branch.

[0076] S6, under conditions of different refractive indices, performing a gait scan of a preset range of angles at a preset step angle through a polarization controller.

[0077] S7 , in each gait, synchronously sampling the second measurement signal corresponding to the measurement branch, the second reference signal corresponding to the reference branch, and the second calibration signal corresponding to the calibration branch.

[0078] In this embodiment of the present invention, the polarization controller is an optical device located before the input end of the fiber isolator in the measurement branch. It is used to precisely control the polarization state of the input light and simulate different polarization state incident conditions to measure the polarization-dependent loss of the fiber isolator.

[0079] The above-mentioned no-load state means that the optical fiber isolator is temporarily removed and the measurement branch only retains the physical state of the optical fiber jumper and the connection port, that is, there is no device under test.

[0080] The refractive index matching cap is a physical component installed at the detection port of the measurement branch. It is filled with a refractive index matching fluid, such as glycerin or specialized optical gel. It is primarily used to eliminate Fresnel reflections at the fiber end face and to provide controllable refractive index boundary conditions by replacing different refractive index matching fluids.

[0081] The preset range angle is the range of polarization state changes that the polarization controller needs to cover, which can be 0°~180° linear or nonlinear polarization rotation. The preset step angle is the angle increment unit for polarization state scanning, which can be 1°~5° / step. The step angle determines the scanning accuracy.

[0082] The above-mentioned second measurement signal is an electrical signal converted from the optical signal output by the measurement branch detection port in a no-load state; the above-mentioned second reference signal is a reference branch electrical signal collected synchronously with the second measurement signal in a no-load state; the above-mentioned second calibration signal is a calibration branch electrical signal collected synchronously with the second measurement signal in a no-load state.

[0083] Specifically, the optical fiber isolator is removed from the measurement branch; a refractive index matching cap is installed at the detection port of the measurement branch. Signal interference caused by end face reflection is eliminated, and a stable optical path environment is established for subsequent polarization scanning. The polarization controller is controlled to rotate stepwise within a preset range at a preset step angle; at each polarization state angle θ k Bottom: Synchronous acquisition of the second measurement signal of the measurement branch (power value P meas ,θ k ); Synchronously acquire the second reference signal of the reference branch (power value P ref ,θ k ); synchronously collect the second calibration signal of the calibration branch (power value P cal ,θ k ).

[0084] In this embodiment, through scanning calibration of all polarization states, the final insertion loss value can cover the actual performance under all polarization states, thereby improving measurement accuracy.

[0085] Optional, such as Figure 3 As shown, the step of determining the initial insertion loss value of the optical fiber isolator based on the first measurement signal and the first reference signal specifically includes:

[0086] S21, when the optical fiber isolator is in a no-load state, determining a splitting ratio parameter of the optical fiber splitter.

[0087] S22 , determining a first splitting ratio and a second splitting ratio corresponding to the measurement branch and the reference branch by using a splitting ratio parameter of the optical fiber splitter.

[0088] S23: Determine an adjustment coefficient based on the first splitting ratio and the second splitting ratio.

[0089] S24 , performing weighted calculation on the ratio between the first measurement signal and the first reference signal according to the adjustment coefficient to obtain an initial insertion loss value of the optical fiber isolator.

[0090] In the embodiment of the present invention, the splitting ratio parameter refers to the inherent splitting ratio of each branch of the optical fiber splitter, such as measurement: reference: calibration = k m :k r :k c This splitting ratio is an inherent property of the device, but may drift due to temperature and / or wavelength. Since the target light wave is a light source with a fixed wavelength, only the drift due to temperature is considered in this embodiment.

[0091] The first splitting ratio refers to the splitting ratio of the measurement branch (k m :(k m +k r +k c )), the second splitting ratio refers to the splitting ratio of the reference branch (k r :(k m +k r +k c )), can be calibrated by no-load state experiment. It should be noted that the splitting ratio of the calibration branch is (k c :(k m +k r +k c )), the sum of the splitting ratios of the three branches is 1.

[0092] The above adjustment coefficient is a correction factor derived based on the first splitting ratio and the second splitting ratio, which is used to eliminate the splitting ratio drift error. Calculation formula: k=[k m :(k m +k r +k c )] / [k r :(k m +k r +k c )].

[0093] Calculate the first measurement signal P meas With the first reference signal P ref The adjustment coefficient k is used as a weight and multiplied by the ratio to obtain the initial insertion loss value of the optical fiber isolator.

[0094] In this embodiment, the adjustment coefficient is obtained by using the splitting ratio parameter, and is used to adjust the initial insertion loss values ​​corresponding to different splitting ratios so that the initial insertion loss value is more consistent with the splitting ratio parameter.

[0095] Optional, such as Figure 4 As shown, the step of determining the connection compensation parameter of the optical fiber isolator according to the first reference signal and the first calibration signal specifically includes:

[0096] S31: Calculate a no-load loss deviation based on the second measurement signal and the second reference signal.

[0097] S32: Predicting the actual load loss deviation based on the no-load loss deviation and the first measurement signal.

[0098] S33: Determine connection compensation parameters of the optical fiber isolator based on the actual load loss deviation.

[0099] In the embodiment of the present invention, the no-load loss deviation is the calibrated loss difference between the measurement branch and the reference branch in the no-load state (without optical fiber isolator), which is caused by optical path asymmetry, splitting ratio deviation, optical fiber length difference, etc. No-load loss deviation δL empty Calculated by the following formula:

[0100] ;

[0101] Wherein, N is the number corresponding to the step angle.

[0102] The above-mentioned actual load loss deviation is the random loss caused only by contact (plugging) loss in the loaded state (with optical fiber isolators installed), and is used to account for the additional attenuation caused by plugging and unplugging during the current test cycle.

[0103] The no-load loss deviation δL is obtained empty , you can find the no-load loss deviation δL empty The corresponding second measurement signal P meas ,θ k , calculate the second measurement signal P meas ,θ k With the first measurement signal P meas The deviation ratio between the two is multiplied by the load loss deviation according to the deviation ratio to obtain the actual load loss deviation. Specifically, the second measurement signal P meas ,θ k With the first measurement signal P meas The deviation ratio between them is (|P meas ,θ k -P meas |) / (P meas ,θ k +P meas ).

[0104] After the actual load loss deviation is obtained, the actual load loss deviation can be directly determined as a connection compensation parameter of the optical fiber isolator.

[0105] In this embodiment, no-load data is used to predict loaded connection loss, thereby avoiding additional measurements in the loaded state and improving the efficiency of obtaining connection compensation parameters.

[0106] Optional, such as Figure 5 As shown, the optical path compensation parameters include polarization compensation parameters, and the step of obtaining the optical path compensation parameters specifically includes:

[0107] S41 : Determine, according to the second measurement signal of each gait, a first signal sequence corresponding to the second measurement signal.

[0108] S42: Determine, according to the second reference signal of each gait, a second signal sequence corresponding to the second reference signal.

[0109] S43: Determine a third signal sequence corresponding to the second calibration signal according to the second calibration signal of each gait.

[0110] S44: Determine polarization compensation parameters based on the first signal sequence, the second signal sequence, the third signal sequence, and the overall optical path diagram.

[0111] In an embodiment of the present invention, polarization compensation parameters are used to correct optical path asymmetry errors caused by changes in polarization states. The first signal sequence is the second set of measurement signals for all gaits of the measurement branch during an unloaded polarization scan. The second signal sequence is the second set of reference signals for the calibration branch during the corresponding gaits during an unloaded polarization scan. The third signal sequence is the second set of calibration signals for the reference branch during the corresponding gaits during an unloaded polarization scan.

[0112] The above-mentioned overall optical path diagram can be understood as a topological structure diagram including the optical fiber splitter, the parameters of each branch optical fiber (length and / or bending state, etc.), and the connector type. In the overall optical path diagram, the nodes are optical devices, the edges are optical fibers, and the edge values ​​are determined according to the optical fiber parameters. The longer the optical fiber length, the smaller the edge value, and vice versa; the greater the bending state (curvature) of the edge, the smaller the edge value, and vice versa. In one possible embodiment, to more accurately describe the overall optical path diagram, the edge value can be calculated using the following formula:

[0113] ;

[0114] in, is the edge value, which represents the optical transmission efficiency coefficient from node i to j. Benchmark efficiency for optical fiber manufacturing, is the fiber length from node i to j, is the average curvature of the optical fiber from node i to j, is the material attenuation coefficient (obtained by looking up the table, a fixed value), is the nonlinear length attenuation factor, and its value is [0.1, 0.5]. is the length attenuation curvature parameter, and its value is [1, 5]. is the bending loss sensitivity coefficient, and its value is [0.01, 0.1]. is the main order of curvature, which takes a value of 2 or 3. is the curvature high-order correction index, and its value is [0.5,1]. is the critical curvature threshold, and its value is [30,60].

[0115] After obtaining the first signal sequence, the second signal sequence, the third signal sequence, and the overall optical path diagram, the theoretical values ​​of the polarization compensation parameters under different polarization states can be calculated using optical path simulation software (such as OptiSystem), and the polarization compensation parameters corresponding to the first measurement value under the current polarization state can be determined from the theoretical values.

[0116] In this embodiment, the polarization compensation parameter is calculated using the full polarization state of each branch, so that the polarization compensation parameter can be determined more accurately.

[0117] Optional, such as Figure 6 As shown, based on the first signal sequence, the second signal sequence, the third signal sequence and the overall optical path diagram, determining the polarization compensation parameter includes:

[0118] S441, obtain a training data set and a spatiotemporal convolutional model to be trained.

[0119] Among them, the training data set includes four-tuple sample data and polarization compensation parameter annotation data corresponding to the four-tuple sample data. The four-tuple sample data includes the first signal sequence sample, the second signal sequence sample, the third signal sequence sample and the overall optical path diagram sample. The input of the spatiotemporal convolution model to be trained is the four-tuple sample data, and the output is the polarization compensation parameter prediction data.

[0120] S442: The spatiotemporal convolution model to be trained is trained using the training data set. After the training is completed, a trained spatiotemporal convolution model is obtained.

[0121] S443 , processing the first signal sequence, the second signal sequence, the third signal sequence, and the overall optical path diagram using the trained spatiotemporal convolution model to determine polarization compensation parameters.

[0122] In an embodiment of the present invention, the first signal sequence sample, the second signal sequence sample, and the third signal sequence sample are constructed using the construction method of the first signal sequence, the second signal sequence, and the third signal sequence. The polarization compensation parameter annotation data may be actual polarization compensation values ​​measured by a high-precision polarization analyzer.

[0123] The spatiotemporal convolutional model to be trained includes a sequence processing branch and a graph processing branch, a feature fusion module, and an output module. The sequence processing branch includes three parallel processing branches: the first, second, and third sequence processing branches. Each sequence processing branch extracts features from its corresponding input signal sequence (the first, second, and third signal sequences) through a one-dimensional convolutional layer (Conv1D). These features are then further processed through a temporal feature extraction module (such as an LSTM or Transformer) to produce three corresponding feature vectors. The graph processing branch processes the overall optical path graph through a graph convolutional network (GCN) or a graph attention network (GAT) to produce a graph embedding vector. The feature fusion module concatenates the feature vectors from the three sequence branches with the graph embedding vector, and then regresses the fully connected layer in the output module to output a single numerical value (i.e., the predicted polarization compensation parameter value).

[0124] In a specific training process, the four-tuple sample data is input into the space-time convolution model to be trained for calculation and processing, the polarization compensation parameter prediction value is output by the space-time convolution model to be trained, and the error loss value between the polarization compensation parameter prediction value and the true polarization compensation value is calculated by the loss function. The model parameters in the space-time convolution model to be trained are adjusted with minimizing the error loss value as the optimization goal, and the adjustment process of the model parameters is iterated until the error loss value is less than the preset value, or the number of iterations reaches the preset number, and the training is stopped to obtain a trained space-time convolution model. After obtaining the trained space-time convolution model, the first signal sequence, the second signal sequence, the third signal sequence and the overall optical path diagram are processed by the trained space-time convolution model to output the polarization compensation parameters. The above-mentioned loss function can be a cross entropy loss function or a mean square error loss function.

[0125] After obtaining the trained spatiotemporal convolution model, the trained spatiotemporal convolution model can be lightweighted to reduce the amount of data in the model, so that the lightweight model can be deployed to the local terminal for calling, reducing the hardware requirements of the local terminal.

[0126] Optional, such as Figure 7 As shown, the optical path compensation parameter also includes a temperature compensation parameter, and the step of obtaining the optical path compensation parameter specifically further includes:

[0127] S45, collecting the temperature value of the optical fiber splitter body in real time.

[0128] S46: Determine a splitting ratio drift compensation coefficient according to the temperature value.

[0129] S47 , determining a temperature compensation parameter based on the splitting ratio drift compensation coefficient and a preset reference temperature.

[0130] In the embodiment of the present invention, the temperature compensation parameter is used to correct the error introduced by the splitting ratio drift caused by temperature change, and together with the polarization compensation parameter, constitutes a complete optical path compensation parameter.

[0131] The temperature value of the optical fiber splitter body can be collected in real time by the NTC thermistor mounted on the splitter housing.

[0132] The split ratio drift compensation coefficient can be understood as a temperature-sensitive factor, describing the relationship between the split ratio change rate and temperature. This relationship is described by the following formula:

[0133] ;

[0134] in, is the splitting ratio drift compensation coefficient, is the reference branch splitting ratio The relative change of T is the temperature. This relationship means that when the temperature rises by 1℃, the reference branch splitting ratio The relative change of .

[0135] Base temperature The reference temperature (usually 25°C) used to calibrate the splitting ratio parameters of the splitter can be stored in the device memory.

[0136] Specifically, the thermistor is placed close to the outer shell of the optical fiber splitter, and a temperature sequence {T1, T2, ..., T n}, temperature value You can take {T1,T2,...,T n The splitting ratio drift compensation coefficient can be calculated by the above formula You can also look up the split ratio drift compensation coefficient corresponding to the current temperature value by looking up the table. .

[0137] After determining the splitting ratio drift compensation coefficient After that, the temperature compensation parameters can be calculated by the following formula :

[0138] ;

[0139] in, is the length scaling factor, specifically .

[0140] In this embodiment, the temperature compensation parameter is determined by the splitting ratio drift compensation coefficient, and the effect of temperature on the splitting ratio drift of the optical fiber splitter is taken into consideration. The temperature compensation parameter can be obtained more accurately, thereby improving the accuracy of the insertion loss value.

[0141] Optional, such as Figure 8 As shown, the step of determining the splitting ratio drift compensation coefficient according to the temperature value specifically includes:

[0142] S471, obtaining a pre-calibrated temperature-splitting ratio drift relationship curve.

[0143] S472 , querying the temperature-splitting ratio drift relationship curve according to the temperature value, and obtaining the splitting ratio drift amount corresponding to the temperature value.

[0144] S473 , calculating a splitting ratio drift compensation coefficient based on a ratio of the splitting ratio drift to the splitting ratio at a reference temperature.

[0145] In an embodiment of the present invention, the temperature-splitting ratio drift relationship curve can be a mapping relationship curve between the temperature (T) calibrated when the splitter leaves the factory and the splitting ratio change (Δk), which can be stored as a two-dimensional lookup table. After the temperature value is determined, the splitting ratio change corresponding to the temperature value can be found through the two-dimensional lookup table.

[0146] The above splitting ratio drift can be understood as the deviation of the reference branch splitting ratio at the current temperature relative to the reference temperature. = Nominal splitting ratio of the reference branch at 25°C.

[0147] The above splitting ratio drift compensation coefficient can be calculated by the following formula:

[0148] ;

[0149] in, is the reference branch splitting ratio, specifically , is the splitting ratio at the reference temperature.

[0150] In this embodiment, the temperature-splitting ratio drift relationship curve can be used to quickly find the splitting ratio drift compensation coefficient corresponding to the temperature value, thereby quickly determining the temperature compensation parameter.

[0151] Optionally, the step of obtaining a pre-calibrated temperature-splitting ratio drift relationship curve specifically includes:

[0152] S4711, placing the optical fiber splitter in a temperature-controlled environment while the target light source transmits a modulated optical signal.

[0153] S4712: Adjust the temperature within the preset temperature range with a preset temperature step size, and after each temperature point stabilizes, synchronously collect the third reference signal value corresponding to the reference branch and the third calibration signal value corresponding to the calibration branch.

[0154] S4713 , calculating the splitting ratio drift at each temperature point based on the third reference signal value and the third calibration signal value, performing polynomial fitting on the splitting ratio drift at each temperature point, and generating a temperature-splitting ratio drift relationship curve.

[0155] In an embodiment of the present invention, the temperature-controlled environment may be a precisely temperature-controlled constant temperature test chamber (such as Thermotron 3800) with a temperature control accuracy of ±0.1° C. and support for programmed temperature scanning.

[0156] The above preset temperature range can be understood as the operating temperature range of the fiber optic splitter, which is generally [-10°C, 60°C] and can cover industrial-grade application scenarios.

[0157] The above-mentioned preset temperature step can be understood as the minimum interval of temperature change, which can be 5°C. In a possible embodiment, temperature control is performed with a first temperature step (5°C) in the linear region, and with a second temperature step (2°C) in the nonlinear region, and the first temperature step is larger than the second temperature step.

[0158] The third reference signal value is the photoelectric conversion signal value of the reference branch in a stable state at the temperature point T, and the third calibration signal value is the photoelectric conversion signal value of the calibration branch in a stable state at the temperature point T.

[0159] Polynomial fitting can be understood as approximating discrete data points through polynomial functions, thereby forming a curve from the discrete data points to obtain a temperature-splitting ratio drift relationship curve.

[0160] Specifically, set the temperature range to [-10℃, 60℃], the step length is 5℃, each temperature point belongs to [-10, -5, 0,..., 60], and raise or lower the temperature of the constant temperature box to T k , measure the real-time temperature T current , when |T current −T k When the temperature is less than 0.2℃ for 5 minutes, thermal equilibrium is achieved. At this time, the reference branch signal and the calibration branch signal are collected synchronously to obtain the reference branch signal P ref (T k ) and calibration branch signal P cal (T k ), at the reference temperature =25℃ additional collection reference value P ref (25), P cal (25).

[0161] The splitting ratio drift at each temperature point is calculated using the following formula:

[0162] ;

[0163] In the above formula, 25°C is used as the benchmark, and the change in the ratio of the reference signal to the calibration signal reflects the drift of the splitting ratio, eliminating the influence of light source fluctuations.

[0164] The above polynomial fitting can be a weighted least squares method, as shown in the following formula:

[0165] ;

[0166] ;

[0167] in, is the drift of the splitting ratio at each temperature point, a is the cubic coefficient, b is the quadratic coefficient, c is the 1st coefficient, and d is the 0th coefficient. is the weight, is the standard deviation of the temperature points of the reference branch. The solution can be solved by matrix iteration, as shown in the following matrix solution formula:

[0168] ;

[0169] Among them, a, b, c, and d are the polynomial solution targets, and the temperature-splitting ratio drift relationship curve is fitted by a, b, c, and d.

[0170] In this embodiment, by controlling the temperature and calculating the splitting ratio drift at each temperature point, a more accurate temperature-splitting ratio drift curve can be obtained. Furthermore, using the third reference signal value and the third calibration signal value to calculate the splitting ratio drift at each temperature point can reflect splitting ratio drift and eliminate the influence of light source fluctuations.

[0171] Optionally, the step of compensating the initial insertion loss value based on the optical path compensation parameter and the connection compensation parameter to obtain the insertion loss in the optical fiber isolator specifically includes:

[0172] Based on the connection compensation parameter, the polarization compensation parameter and the temperature compensation parameter, the initial insertion loss value is compensated to obtain the insertion loss value in the optical fiber isolator.

[0173] In the embodiment of the present invention, the connection compensation parameter corresponds to the connection loss, the polarization compensation parameter corresponds to the polarization loss, and the temperature compensation parameter corresponds to the temperature loss.

[0174] It can be understood that the initial insertion loss value includes connection loss, polarization loss, and temperature loss. Therefore, the measured initial insertion loss value is larger than the actual insertion loss. Therefore, the connection compensation parameter, polarization compensation parameter, and temperature compensation parameter can be subtracted from the initial insertion loss value to obtain the final insertion loss value.

[0175] In a possible embodiment, if the final insertion loss is greater than the initial insertion loss value, it is considered that the loss is abnormal and an alarm may be issued.

[0176] Those skilled in the art will appreciate that all or part of the processes in the above-described method embodiments can be implemented by instructing related hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When executed, the program can include the processes in the above-described method embodiments. The storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM).

[0177] The above disclosure is merely a preferred embodiment of the present invention and certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for measuring insertion loss in an optical fiber isolator, characterized in that: The optical fiber isolator is provided on a measurement branch branched out by an optical fiber splitter, and the optical fiber splitter further branches out a reference branch and a calibration branch. A target light source transmits a modulated optical signal, and the optical signal enters the measurement branch, the reference branch, and the calibration branch respectively through the optical fiber splitter. The method comprises the following steps: detecting a first measurement signal corresponding to the measurement branch, a first reference signal corresponding to the reference branch, and a first calibration signal corresponding to the calibration branch; determining an initial insertion loss value of the optical fiber isolator based on the first measurement signal and the first reference signal; determining a connection compensation parameter of the optical fiber isolator according to the first reference signal and the first calibration signal; An optical path compensation parameter is obtained, and based on the optical path compensation parameter and the connection compensation parameter, the initial insertion loss value is compensated to obtain an insertion loss in the optical fiber isolator.

2. The method for measuring insertion loss in an optical fiber isolator according to claim 1, wherein: The measurement branch is provided with a polarization controller, and the polarization controller is provided before the optical fiber isolator. Before the step of detecting the first measurement signal corresponding to the measurement branch, the first reference signal corresponding to the reference branch, and the first calibration signal corresponding to the calibration branch, the method further includes: When the optical fiber isolator is in an unloaded state, installing a refractive index matching cap on the detection port of the measurement branch; In the case of different refractive indices, the polarization controller is used to perform a gait scan over a preset range of angles at a preset step angle; In each gait, the second measurement signal corresponding to the measurement branch, the second reference signal corresponding to the reference branch, and the second calibration signal corresponding to the calibration branch are synchronously sampled.

3. The method for measuring insertion loss in an optical fiber isolator according to claim 2, wherein: The step of determining an initial insertion loss value of the optical fiber isolator based on the first measurement signal and the first reference signal specifically includes: When the optical fiber isolator is in an unloaded state, determining a splitting ratio parameter of the optical fiber splitter; Determining a first splitting ratio and a second splitting ratio corresponding to the measurement branch and the reference branch by using a splitting ratio parameter of the optical fiber splitter; determining an adjustment coefficient based on the first splitting ratio and the second splitting ratio; A weighted calculation is performed on the ratio of the first measurement signal to the first reference signal according to the adjustment coefficient to obtain an initial insertion loss value of the optical fiber isolator.

4. The method for measuring insertion loss in an optical fiber isolator according to claim 3, wherein: The step of determining the connection compensation parameter of the optical fiber isolator according to the first reference signal and the first calibration signal specifically includes: calculating a no-load loss deviation based on the second measurement signal and the second reference signal; predicting a loaded loss deviation based on the no-load loss deviation and the first measurement signal; Based on the actual load loss deviation, a connection compensation parameter of the optical fiber isolator is determined.

5. The method for measuring insertion loss in an optical fiber isolator according to claim 4, wherein: The optical path compensation parameters include polarization compensation parameters, and the steps of obtaining the optical path compensation parameters specifically include: determining, according to the second measurement signal of each gait, a first signal sequence corresponding to the second measurement signal; determining, according to the second reference signal of each gait, a second signal sequence corresponding to the second reference signal; determining, based on the second calibration signal of each gait, a third signal sequence corresponding to the second calibration signal; Polarization compensation parameters are determined based on the first signal sequence, the second signal sequence, the third signal sequence, and the overall optical path diagram.

6. The method for measuring insertion loss in an optical fiber isolator according to claim 5, wherein: Determining a polarization compensation parameter based on the first signal sequence, the second signal sequence, the third signal sequence, and the overall optical path diagram includes: Obtaining a training data set and a spatiotemporal convolution model to be trained, wherein the training data set includes quadruple sample data and polarization compensation parameter annotation data corresponding to the quadruple sample data, the quadruple sample data including a first signal sequence sample, a second signal sequence sample, a third signal sequence sample, and an overall optical path diagram sample, the input of the spatiotemporal convolution model to be trained is the quadruple sample data, and the output is polarization compensation parameter prediction data; Training the to-be-trained spatiotemporal convolutional model using the training data set, and obtaining a trained spatiotemporal convolutional model after the training is completed; The first signal sequence, the second signal sequence, the third signal sequence and the overall optical path diagram are processed by the trained spatiotemporal convolution model to determine polarization compensation parameters.

7. The method for measuring insertion loss in an optical fiber isolator according to claim 6, wherein: The optical path compensation parameters also include temperature compensation parameters, and the step of obtaining the optical path compensation parameters specifically includes: collecting the temperature value of the optical fiber splitter body in real time; determining a splitting ratio drift compensation coefficient according to the temperature value; The temperature compensation parameter is determined based on the splitting ratio drift compensation coefficient and a preset reference temperature.

8. The method for measuring insertion loss in an optical fiber isolator according to claim 7, wherein: The step of determining the splitting ratio drift compensation coefficient according to the temperature value specifically includes: Obtain a pre-calibrated temperature-splitting ratio drift curve; querying the temperature-splitting ratio drift relationship curve according to the temperature value to obtain the splitting ratio drift amount corresponding to the temperature value; The splitting ratio drift compensation coefficient is calculated based on the ratio of the splitting ratio drift to the splitting ratio at a reference temperature.

9. The method for measuring insertion loss in an optical fiber isolator according to claim 8, wherein: The steps of obtaining a pre-calibrated temperature-splitting ratio drift relationship curve specifically include: placing the optical fiber splitter in a temperature-controlled environment while the target light source transmits a modulated optical signal; Adjusting the temperature within a preset temperature range with a preset temperature step size, and synchronously collecting a third reference signal value corresponding to the reference branch and a third calibration signal value corresponding to the calibration branch after each temperature point stabilizes; Based on the third reference signal value and the third calibration signal value, the splitting ratio drift at each temperature point is calculated, and a polynomial fitting is performed on the splitting ratio drift at each temperature point to generate the temperature-splitting ratio drift relationship curve.

10. The method for measuring insertion loss in an optical fiber isolator according to claim 9, wherein: The step of compensating the initial insertion loss value based on the optical path compensation parameter and the connection compensation parameter to obtain the insertion loss in the optical fiber isolator specifically includes: The initial insertion loss value is compensated based on the connection compensation parameter, the polarization compensation parameter, and the temperature compensation parameter to obtain the insertion loss in the optical fiber isolator.

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