A method and device for measuring crosstalk between modes

Abstract

The present invention provides a method and device for measuring inter-mode crosstalk, the device comprising: a light source module, the light source module is connected to the input end of the discrete mode device under test, and is used to provide linearly polarized light; an acquisition module, the acquisition module is optically connected to the discrete mode device under test, and is used to acquire the optical frequency domain waveform of the light field on the image plane at the optical mode field, the optical mode field is the light field emitted by the end face of the few-mode pigtail of the discrete mode device under test under the action of the linearly polarized light; a processing module is connected to the acquisition unit, and is used to acquire the inter-mode crosstalk information of the discrete mode device under test according to the optical frequency domain waveform of the light field. The scheme of the present invention can simply and accurately measure the inter-mode crosstalk of the discrete mode device.

Description

Technical Field

[0001] The present invention relates to the field of transmission and IP technology, and in particular to a method and device for measuring crosstalk between modes. Background Art

[0002] With the continuous increase of network users and the emergence of new network data services, the demand for network capacity is growing. The current optical communication system based on ordinary single-mode fiber can no longer cope with the booming network capacity demand. The mode in few-mode fiber (FMF) as a new optical multiplexing dimension has attracted widespread attention worldwide.

[0003] To realize the mode division multiplexing (MDM) optical transmission system, in addition to few-mode optical fiber, it is also necessary to use matching discrete mode devices, such as mode converter (MC), mode multiplexer / demultiplexer (Mode MUX / DEMUX), etc. These discrete mode devices together with few-mode optical fiber determine the performance of the mode division multiplexing optical transmission system. Therefore, how to accurately measure the inter-mode crosstalk level of these discrete mode devices has become a top priority. As a representative of discrete mode devices, the discrete inter-mode crosstalk measurement of mode multiplexers / demultiplexers has been studied more. There are currently two main methods: mode demultiplexing method and mode stripping method. However, the existing two discrete mode device inter-mode crosstalk measurement schemes are difficult to accurately measure the inter-mode crosstalk level of discrete mode devices. Summary of the invention

[0004] The object of the present invention is to provide an inter-mode crosstalk measurement method and device to solve the problem that existing inter-mode crosstalk measurement solutions are difficult to accurately measure the inter-mode crosstalk level of discrete mode devices.

[0005] An embodiment of the present invention provides an inter-mode crosstalk measurement device, comprising:

[0006] A light source module, the light source module is connected to the input end of the discrete mode device to be tested, and is used to provide linearly polarized light;

[0007] An acquisition module, the acquisition module is optically connected to the discrete mode device under test, and is used to acquire an optical frequency domain waveform of the light field on an image plane at the optical mode field, wherein the optical mode field is a light field emitted by the end face of the few-mode pigtail of the discrete mode device under test under the action of the linearly polarized light;

[0008] A processing module is connected to the acquisition module and is used to acquire the inter-mode crosstalk information of the discrete mode device under test according to the optical frequency domain waveform of the optical field.

[0009] Wherein, the light source module comprises:

[0010] A light source unit, the light source unit is used to emit a wide-spectrum continuous laser;

[0011] A polarizer is connected to the light source unit and the input end of the discrete mode device to be measured, respectively, and is used for converting the wide-spectrum continuous laser emitted by the light source unit into linearly polarized light.

[0012] Wherein, the acquisition module includes:

[0013] A mode field amplification unit, the mode field amplification unit is optically connected to the discrete mode device under test, and is used to amplify the optical mode field emitted by the end face of the few-mode pigtail of the discrete mode device under test, wherein the output end of the discrete mode device under test is located at the object focus of the mode field amplification unit;

[0014] An image plane light field acquisition unit, used to collect the light field on the image plane where the amplified light mode field is located, wherein the single-mode optical fiber input end of the image plane light field acquisition unit is located at the image side focal plane of the mode field amplification unit;

[0015] A spectrometer is optically connected to the image plane light field acquisition unit and is used to obtain the optical frequency domain waveform of the light field.

[0016] Wherein, the processing module includes:

[0017] A detection unit, wherein the detection unit is connected to the image plane light field acquisition unit and the spectrometer respectively, and is used to control the image plane light field acquisition unit to collect the light field, and obtain the inter-mode crosstalk information of the discrete mode device under test according to the optical frequency domain waveform obtained by the spectrometer.

[0018] The light field includes: a light field of (2N+1)×(2N+1) collection points, wherein the coordinates (N, N) of the center collection point of the (2N+1)×(2N+1) collection points are the coordinates of the single-mode optical fiber input end of the image plane light field collection unit on the image side focal plane when the light power collected on the spectrometer is maximum.

[0019] Wherein, the detection unit comprises:

[0020] A first acquisition subunit is used to perform an inverse Fourier transform on the optical frequency domain waveform I(x, y, ω) of the acquisition point to obtain a discrete point B(x, y, t) in the time domain, wherein x represents the abscissa of the acquisition point, y represents the ordinate of the acquisition point, ω represents the frequency of the optical spectrum waveform, and t represents the time delay between the crosstalk mode and the main mode of the discrete mode device under test;

[0021] A second acquisition subunit is used to acquire the mode field strength of the main mode of the discrete mode device under test at the acquisition point and the mode field strength of the crosstalk mode excited by the discrete mode device under test at the acquisition point according to the time domain discrete point;

[0022] The third acquisition subunit is used to acquire inter-mode crosstalk information between the main mode and the crosstalk mode of the discrete mode device under test according to the mode field strength of the main mode at the acquisition point and the mode field strength of the crosstalk mode at the acquisition point.

[0023] Wherein, the second acquisition subunit is specifically used for:

[0024] According to the time domain discrete points, acquiring a power ratio of the crosstalk mode to the main mode at the collection point;

[0025] The mode field strength of the main mode of the discrete mode device under test at the collection point and the mode field strength of the crosstalk mode at the collection point are obtained according to the power ratio.

[0026] Wherein, the second acquisition subunit is obtained by formula Acquire a power ratio of the crosstalk mode to the main mode at the collection point;

[0027] Wherein, α(x, y, τ) represents the power ratio of the crosstalk mode to the main mode at the acquisition point, τ represents the time delay between the crosstalk pattern and the main pattern.

[0028] The second acquisition subunit is used to obtain Obtain the mode field strength of the main mode at the acquisition point, and use the formula Obtaining the mode field strength of the crosstalk mode at the acquisition point;

[0029] Among them, I T (x, y) is the total power of the spectrum collected at the collection point on the image plane, I A (x, y) is the mode field strength of the main mode at the acquisition point, I B (x, y) is the mode field strength of the crosstalk mode at the acquisition point.

[0030] The third acquisition subunit is used to obtain the inter-mode crosstalk information between the main mode of the discrete mode device under test and the crosstalk mode through the following formula;

[0031]

[0032] Among them, XT B→AIndicates inter-mode crosstalk information between the main mode and the crosstalk mode.

[0033] An embodiment of the present invention further provides a method for measuring inter-mode crosstalk, including:

[0034] Acquire an optical frequency domain waveform of the optical field on an image plane at the optical mode field, wherein the optical mode field is the optical field emitted by the end face of the few-mode pigtail of the discrete mode device under the action of the linearly polarized light;

[0035] The inter-mode crosstalk information of the discrete mode device under test is obtained according to the optical frequency domain waveform of the optical field.

[0036] Wherein, the light field comprises: a light field of at least one acquisition point;

[0037] The step of obtaining the inter-mode crosstalk information of the discrete mode device under test according to the optical frequency domain waveform of the optical field comprises:

[0038] Performing an inverse Fourier transform on the optical frequency domain waveform I(x, y, ω) of the acquisition point to obtain a time domain discrete point B(x, y, t), wherein x represents the abscissa of the acquisition point, y represents the ordinate of the acquisition point, ω represents the frequency of the optical spectrum waveform, and t represents the time delay between the crosstalk mode and the main mode of the discrete mode device under test;

[0039] Acquire, according to the time domain discrete points, the mode field strength of the main mode of the discrete mode device under test at the acquisition points and the mode field strength of the crosstalk mode excited by the discrete mode device under test at the acquisition points;

[0040] According to the mode field strength of the main mode at the acquisition point and the mode field strength of the crosstalk mode at the acquisition point, inter-mode crosstalk information between the main mode and the crosstalk mode of the discrete mode device under test is obtained.

[0041] Wherein, obtaining the mode field strength of the main mode of the discrete mode device under test and the mode field strength of the crosstalk mode excited by the discrete mode device under test according to the time domain discrete points includes:

[0042] According to the time domain discrete points, acquiring a power ratio of the crosstalk mode to the main mode at the collection point;

[0043] The mode field strength of the main mode of the discrete mode device under test at the collection point and the mode field strength of the crosstalk mode at the collection point are obtained according to the power ratio.

[0044] Wherein, acquiring the power ratio of the crosstalk mode and the main mode at the collection point according to the time domain discrete point includes:

[0045] By formula Acquire a power ratio of the crosstalk mode to the main mode at the collection point;

[0046] Wherein, α(x, y, τ) represents the power ratio of the crosstalk mode to the main mode at the acquisition point, τ represents the time delay between the crosstalk pattern and the main pattern.

[0047] Wherein, obtaining the mode field strength of the main mode of the measured discrete mode device at the collection point and the mode field strength of the crosstalk mode at the collection point according to the power ratio includes:

[0048] By formula Acquire the mode field strength of the main mode at the acquisition point;

[0049] By formula Obtaining the mode field strength of the crosstalk mode at the acquisition point;

[0050] Among them, I T (x, y) is the total power of the spectrum collected at the collection point on the image plane, I A (x, y) is the mode field strength of the main mode at the acquisition point, I B (x, y) is the mode field strength of the crosstalk mode at the acquisition point.

[0051] Wherein, acquiring the inter-mode crosstalk information between the main mode and the crosstalk mode of the discrete mode device under test according to the mode field strength of the main mode at the collection point and the mode field strength of the crosstalk mode at the collection point comprises:

[0052] By formula Obtaining the inter-mode crosstalk information;

[0053] Among them, XT B→A It represents the inter-mode crosstalk information between the main mode and the crosstalk mode, and the number of the at least one acquisition point is (2N+1)×(2N+1), where N is a natural number.

[0054] An embodiment of the present invention further provides an inter-mode crosstalk measurement device, comprising: a transceiver and a processor:

[0055] The processor is used to obtain an optical frequency domain waveform of the light field on an image plane where the optical mode field is located, wherein the optical mode field is the light field emitted by the few-mode pigtail end face of the discrete mode device under the action of the linearly polarized light; and obtain inter-mode crosstalk information of the discrete mode device under test based on the optical frequency domain waveform of the light field.

[0056] Wherein, the light field comprises: a light field of at least one acquisition point;

[0057] The processor is used to perform an inverse Fourier transform on the optical frequency domain waveform I(x, y, ω) of the acquisition point to obtain a time domain discrete point B(x, y, t), wherein x represents the abscissa of the acquisition point, y represents the ordinate of the acquisition point, ω represents the frequency of the optical spectrum waveform, and t is the time delay between the crosstalk mode and the main mode of the discrete mode device under test; based on the time domain discrete points, obtain the mode field strength of the main mode of the discrete mode device under test at the acquisition point and the mode field strength of the crosstalk mode excited by the discrete mode device under test at the acquisition point; based on the mode field strength of the main mode at the acquisition point and the mode field strength of the crosstalk mode at the acquisition point, obtain inter-mode crosstalk information between the main mode of the discrete mode device under test and the crosstalk mode.

[0058] Among them, the processor is used to obtain the power ratio of the crosstalk mode and the main mode at the collection point according to the time domain discrete point; according to the power ratio, obtain the mode field strength of the main mode of the measured discrete mode device at the collection point and the mode field strength of the crosstalk mode at the collection point.

[0059] Wherein, the processor is used for:

[0060] By formula Acquire a power ratio of the crosstalk mode to the main mode at the collection point;

[0061] Wherein, α(x, y, τ) represents the power ratio of the crosstalk mode to the main mode at the acquisition point, τ represents the time delay between the crosstalk pattern and the main pattern.

[0062] Wherein, the processor is used for:

[0063] By formula Acquire the mode field strength of the main mode at the acquisition point;

[0064] By formula Obtaining the mode field strength of the crosstalk mode at the acquisition point;

[0065] Among them, I T (x, y) is the total power of the spectrum collected at the collection point on the image plane, I A (x, y) is the mode field strength of the main mode at the acquisition point, I B (x, y) is the mode field strength of the crosstalk mode at the acquisition point.

[0066] Wherein, the processor is used for:

[0067] By formula Obtaining the inter-mode crosstalk information;

[0068] Among them, XT B→A It represents the inter-mode crosstalk information between the main mode and the crosstalk mode, and the number of the at least one acquisition point is (2N+1)×(2N+1), where N is a natural number.

[0069] An embodiment of the present invention also provides an inter-mode crosstalk measurement device, comprising: a transceiver, a processor, a memory, and a program or instruction stored in the memory and executable on the processor; when the processor executes the program or instruction, the steps in the inter-mode crosstalk measurement method as described above are implemented.

[0070] An embodiment of the present invention further provides a readable storage medium on which a program or instruction is stored. When the program or instruction is executed by a processor, the steps in the above-mentioned inter-mode crosstalk measurement method are implemented.

[0071] The beneficial effects of the above technical solution of the present invention are as follows:

[0072] In the inter-mode crosstalk measurement device of the embodiment of the present invention, the acquisition module acquires the optical frequency domain waveform of the optical field on the image plane at the optical mode field, the optical mode field is the optical field emitted by the end face of the few-mode pigtail of the discrete mode device under the action of the linear polarized light, and the processing module acquires the inter-mode crosstalk information of the discrete mode device under test according to the optical frequency domain waveform of the optical field. The inter-mode crosstalk of the discrete mode device can be measured simply and accurately by the measurement device. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] Figure 1 This is a schematic diagram of the structure of the device for measuring crosstalk between modes according to an embodiment of the present invention;

[0074] Figure 2 This is one of the structural schematic diagrams of the mode field amplification unit according to an embodiment of the present invention;

[0075] Figure 3 This is a second structural schematic diagram of a mode field amplification unit according to an embodiment of the present invention;

[0076] Figure 4 It is a structural schematic diagram of an image plane light field acquisition unit according to an embodiment of the present invention;

[0077] Figure 5A LP of the embodiment of the present invention 01 Schematic diagram of the normalized optical frequency domain waveform of the mode converter at the acquisition point;

[0078] Figure 5B LP of the embodiment of the present invention11 Schematic diagram of the normalized optical frequency domain waveform of the mode converter at the acquisition point;

[0079] Fig. 6A This is one of the pulse-differential group delay schematic diagrams of an embodiment of the present invention;

[0080] Figure 6B This is the second schematic diagram of pulse-differential group delay according to an embodiment of the present invention;

[0081] Figure 7 A schematic diagram of a flow chart of a method for measuring crosstalk between modes according to an embodiment of the present invention;

[0082] Figure 8 This is a second structural schematic diagram of the device for measuring crosstalk between modes according to an embodiment of the present invention;

[0083] Fig. 9 This is the third structural schematic diagram of the inter-mode crosstalk measurement device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0084] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0085] It should be understood that the references to "one embodiment" or "an embodiment" throughout the specification mean that the specific features, structures, or characteristics associated with the embodiment are included in at least one embodiment of the present invention. Therefore, the references to "in one embodiment" or "in an embodiment" appearing throughout the specification do not necessarily refer to the same embodiment. In addition, these specific features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0086] In various embodiments of the present invention, it should be understood that the size of the serial numbers of the following processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0087] Additionally, the terms "system" and "network" are often used interchangeably herein.

[0088] In the embodiments provided in the present application, it should be understood that "B corresponding to A" means that B is associated with A, and B can be determined according to A. However, it should also be understood that determining B according to A does not mean determining B only according to A, and B can also be determined according to A and / or other information.

[0089] like Figure 1 As shown, an inter-mode crosstalk measurement device according to an embodiment of the present invention includes:

[0090] A light source module 101 is connected to the input end of the discrete mode device under test and is used to provide linearly polarized light.

[0091] The discrete mode device under test refers to a mode-dependent device matched with a few-mode fiber. Few-mode fiber refers to an optical fiber that supports multiple waveguide modes.

[0092] An acquisition module 102 is optically connected to the discrete mode device under test, and is used to acquire the optical frequency domain waveform of the light field on the image plane at the optical mode field, wherein the optical mode field is the light field emitted by the end face of the few-mode pigtail of the discrete mode device under test under the action of the linearly polarized light.

[0093] The length of the few-mode pigtail is between 1m and 100m. The light field obtained may be a light field of at least one acquisition point on the image plane.

[0094] The processing module 103 is connected to the acquisition module and is used to acquire the inter-mode crosstalk information of the discrete mode device under test according to the optical frequency domain waveform of the optical field.

[0095] The mode crosstalk information is the power ratio between other crosstalk modes and the main mode in the discrete mode device under test.

[0096] In the inter-mode crosstalk measurement device of the embodiment of the present invention, the acquisition module acquires the optical frequency domain waveform of the optical field on the image plane at the optical mode field, the optical mode field is the optical field emitted by the end face of the few-mode pigtail of the discrete mode device under the action of the linear polarized light, and the processing module acquires the inter-mode crosstalk information of the discrete mode device under test according to the optical frequency domain waveform of the optical field. The inter-mode crosstalk of the discrete mode device can be measured simply and accurately by the measurement device.

[0097] Optionally, the light source module includes:

[0098] A light source unit, the light source unit is used to emit a wide-spectrum continuous laser;

[0099] A polarizer is connected to the light source unit and the input end of the discrete mode device to be measured, respectively, and is used for converting the wide-spectrum continuous laser emitted by the light source unit into linearly polarized light.

[0100] In the embodiment of the present invention, the working wavelength, spectrum width and laser power of the light source unit are adjustable, and are used to provide wide-spectrum continuous laser. The working wavelength range of the light source unit is continuously adjustable between 850-1650nm, the spectrum width is continuously adjustable between 1-20nm, and the laser power is continuously adjustable between 0-200mW; the above-mentioned polarizer can be a fiber-type polarizer or a crystal-type polarizer.

[0101] Further optionally, the light source unit includes a single-mode optical fiber and a target device, the target device includes at least one of a broadband continuous laser light source, an optical amplifier, an optical attenuator and an optical filter, the broadband continuous laser light source is used to provide broadband continuous laser light, and the working wavelength range is continuously adjustable between 850-1650nm; the optical amplifier is used to amplify the laser band used during operation, that is, the working band; the optical attenuator is used to adjust the optical power; the optical amplifier and the optical attenuator are used to adjust the power of the working band laser to cooperate with the polarizer, the mode field amplification system, the image plane light field acquisition unit and the spectrometer; the optical filter, whose central wavelength is adjustable within the working wavelength range of the broadband continuous laser light source, and the minimum bandwidth is not greater than 1nm, is used to adjust the spectral width of the laser output by the light source unit; the single-mode optical fiber conducts the laser output by the broadband continuous laser light source and forms a fundamental mode, its input end is used for light input, preferably connected to the optical filter, and its output end is used to output light to the polarizer, preferably with a connector at the output end. The single-mode optical fiber is a bare optical fiber or a jumper.

[0102] Optionally, the acquisition module includes:

[0103] A mode field amplification unit, the mode field amplification unit is optically connected to the discrete mode device under test, and is used to amplify the optical mode field emitted by the end face of the few-mode pigtail of the discrete mode device under test, wherein the output end of the discrete mode device under test is located at the object focus of the mode field amplification unit;

[0104] An image plane light field acquisition unit, used to collect the light field on the image plane where the amplified light mode field is located, wherein the single-mode optical fiber input end of the image plane light field acquisition unit is located at the image side focal plane of the mode field amplification unit;

[0105] A spectrometer is optically connected to the image plane light field acquisition unit and is used to obtain the optical frequency domain waveform of the light field.

[0106] In an embodiment of the present invention, the mode field amplification unit can be an amplification system composed of a transmission lens group or a reflective lens group; the output end of the polarizer single-mode optical fiber is located at the object focus of the mode field amplification system, and the input end of the single-mode optical fiber of the image plane light field collection unit is located at the image focal plane of the mode field amplification system; the image plane light field collection unit can be a combination of a manually adjusted or electrically controlled two-dimensional displacement adjustment frame and a single-mode jumper.

[0107] Wherein, when the mode field amplification unit is an amplification system composed of a transmission lens group, such as Figure 2As shown, a first convex lens group 202 and a second convex lens group 203 are arranged along the optical path, the output end of the few-mode pigtail 201 of the discrete mode device under test is at the object focus of the first convex lens group, the first convex lens group 202 and the second convex lens group 203 are coaxially arranged, and the single-mode jumper input end 204 of the image plane light field acquisition unit coincides with the image-side focal plane of the second convex lens group 203.

[0108] The focal length of the first convex lens group of the magnifying system composed of the transmission mirror group should be smaller than that of the second convex lens group, so as to realize the mode field magnification function; the focal length of the first off-axis reflector group of the magnifying system composed of the reflective mirror group should be smaller than that of the second off-axis reflector group, so as to realize the mode field magnification function.

[0109] When the mode field amplification unit is an amplification system composed of a reflective mirror group, such as Figure 3 As shown, a first off-axis reflector group 303 and a second off-axis reflector group 304 are arranged along the optical path, the output end of the few-mode pigtail 301 of the discrete mode device to be measured is at the object-side focus of the first off-axis reflector group 303, and the input end of the single-mode jumper 302 of the image plane light field acquisition unit coincides with the image-side focal plane of the second off-axis reflector group 304. During operation, the laser light of the working wavelength passes through the single-mode optical fiber of the polarizer, and is converged into parallel light or a light beam with a small divergence angle by the first convex lens group or the first off-axis reflector group, and the parallel light beam or the approximately parallel light with a small divergence angle is focused on the image-side focal plane by the second convex lens group or the second off-axis reflector group.

[0110] Preferably, the mode field amplification unit further comprises a bracket for fixing Figure 2 or Figure 3 The optical device shown in the figure is arranged so that the position of the optical device can be adjusted. Specifically, it comprises: a first lens group bracket, which is used to make the output end of the few-mode pigtail of the discrete mode device under test be located at the object focus of the first convex lens group or the first off-axis reflector group; and a second lens group bracket, which is used to make the input end of the single-mode optical fiber of the image plane light field acquisition unit be located at the image-side focal plane of the second convex lens group or the second off-axis reflector group.

[0111] Optionally, the structural schematic diagram of the above-mentioned image plane light field acquisition unit is as follows: Figure 4 As shown, two one-axis translation stages can be used as a horizontal translation stage 401 and a vertical translation stage 402 respectively to form a 2D translation adjustment frame. The single-mode jumper 403 is plugged into a mirror frame 404 and can be connected to the 2D translation adjustment frame via the mirror frame 404. After connection, the azimuth angle of the mirror frame is adjusted so that the single-mode jumper input end face 405 completely coincides with the image-side focal plane of the mode field amplifier.

[0112] Optionally, the processing module includes:

[0113] A detection unit, wherein the detection unit is connected to the image plane light field acquisition unit and the spectrometer respectively, and is used to control the image plane light field acquisition unit to collect the light field, and obtain the inter-mode crosstalk information of the discrete mode device under test according to the optical frequency domain waveform obtained by the spectrometer.

[0114] Optionally, the light field includes a light field of (2N+1)×(2N+1) collection points, wherein the coordinates (N, N) of the center collection point of the (2N+1)×(2N+1) collection points are the coordinates of the single-mode optical fiber input end of the image plane light field collection unit on the image side focal plane when the light power collected on the spectrometer is maximum.

[0115] It should be noted that the above number of collection points is only an example of an embodiment of the present invention and does not constitute a limitation to the present invention. Other numbers of collection points belong to the protection scope of the present invention. For example, the light field includes a light field with an even number of collection points. Optionally, the detection unit includes:

[0116] A first acquisition subunit is used to perform an inverse Fourier transform on the optical frequency domain waveform I(x, y, ω) of the acquisition point to obtain a discrete point B(x, y, t) in the time domain, wherein x represents the abscissa of the acquisition point, y represents the ordinate of the acquisition point, ω represents the frequency of the optical spectrum waveform, and t represents the time delay between the crosstalk mode and the main mode of the discrete mode device under test;

[0117] A second acquisition subunit is used to acquire the mode field strength of the main mode of the discrete mode device under test at the acquisition point and the mode field strength of the crosstalk mode excited by the discrete mode device under test at the acquisition point according to the time domain discrete point;

[0118] The third acquisition subunit is used to acquire inter-mode crosstalk information between the main mode and the crosstalk mode of the discrete mode device under test according to the mode field strength of the main mode at the acquisition point and the mode field strength of the crosstalk mode at the acquisition point.

[0119] In the embodiment of the present invention, the crosstalk mode may include multiple modes. The inter-mode crosstalk measurement device of the embodiment of the present invention may respectively calculate the inter-mode crosstalk information between the main mode and each crosstalk mode. The same calculation method may be used to calculate the inter-mode crosstalk information between the main mode and each crosstalk mode.

[0120] Further optionally, the second acquiring subunit is specifically configured to:

[0121] According to the time domain discrete points, acquiring a power ratio of the crosstalk mode to the main mode at the collection point;

[0122] The mode field strength of the main mode of the discrete mode device under test at the collection point and the mode field strength of the crosstalk mode at the collection point are obtained according to the power ratio.

[0123] Wherein, the second acquisition subunit is obtained by formula Acquire a power ratio of the crosstalk mode to the main mode at the collection point;

[0124] Wherein, α(x, y, τ) represents the power ratio of the crosstalk mode to the main mode at the acquisition point, τ represents the time delay between the crosstalk pattern and the main pattern.

[0125] The second acquisition subunit is used to obtain Obtain the mode field strength of the main mode at the acquisition point, and use the formula Obtaining the mode field strength of the crosstalk mode at the acquisition point;

[0126] Among them, I T (x, y) is the total power of the spectrum collected at the collection point on the image plane, I A (x, y) is the mode field strength of the main mode at the acquisition point, I B (x, y) is the mode field strength of the crosstalk mode at the acquisition point.

[0127] The third acquisition subunit is used to obtain the inter-mode crosstalk information between the main mode of the discrete mode device under test and the crosstalk mode through the following formula;

[0128]

[0129] Among them, XT B→A Indicates inter-mode crosstalk information between the main mode and the crosstalk mode.

[0130] In the embodiment of the present invention, the measurement of the mode crosstalk of the discrete mode device is realized, and it is simple, reliable and highly automated. Therefore, the device can conveniently and accurately measure the mode crosstalk of the discrete mode device, solving the problem that the mode crosstalk of the discrete mode device cannot be accurately measured at present.

[0131] The measurement principle of the inter-mode crosstalk measurement device of the present invention is described below in conjunction with specific embodiments.

[0132] The measurement principle of the inter-mode crosstalk measurement device of the present invention includes:

[0133] 1) Select the discrete mode device to be tested and measure the length L of its few-mode pigtail;

[0134] The discrete mode device under test is LP 01 Mode Converter and LP 11 Mode converter; the LP 01 Mode Converter and LP 11 The length L of the few-mode pigtail of the mode converter is 3.44m, which is the same two-mode optical fiber with connectors at the input and output ends.

[0135] 2) The discrete mode device to be measured is placed between the polarizer and the mode field amplifier unit of the crosstalk measurement device provided by the present invention, and the optical path is adjusted.

[0136] 3) The crosstalk measurement device is placed in a corresponding measurement state, and returns the measured inter-mode crosstalk between the modes in the discrete mode device under test.

[0137] Specifically, they include:

[0138] a) adjusting the output working wavelength of the light source unit to 1534nm to 1554nm and the output power to 23dBm;

[0139] b) inserting a 1 m long single-mode optical fiber between the polarizer and the mode field amplifier unit of the crosstalk measurement device, wherein the input end of the single-mode optical fiber is connected to the single-mode output end of the polarizer, and adjusting the output end thereof to be placed at the object focus of the mode field amplifier unit;

[0140] c) adjusting the image plane light field acquisition unit so that it is located on the image side focal plane of the mode field amplification unit and the light power collected on the spectrometer is maximum, and recording the coordinates of the single-mode jumper input end of the image plane light field acquisition unit on the image side focal plane at this time, setting it to be point (N, N), and setting N to 50;

[0141] d) Selecting a discrete mode device to be measured, placing it between the polarizer and the mode field amplifier unit of the crosstalk measurement device, replacing the 1 m long single-mode optical fiber described in b), connecting its single-mode input end to the single-mode output end of the polarizer, and placing its output end at the object focus of the mode field amplifier system;

[0142] e) Adjust the single-mode jumper input end of the image plane light field acquisition unit to be located at the acquisition origin (0,0) on the image focal plane. From the perspective of the optical path propagation direction, the acquisition origin (0,0) is N×s to the left of point (N,N) in the horizontal direction and N×s below in the vertical direction, where s is the displacement step of the image plane light field acquisition unit. Assume that the displacement step s of the image plane light field acquisition unit is 10um, and the acquisition origin (0,0) is 500um to the left of point (50,50) in the horizontal direction and 500um below in the vertical direction;

[0143] f) Starting from the acquisition origin (0,0), the image plane light field acquisition unit scans a (2N+1)×(2N+1) acquisition point square matrix upward and rightward, and the four vertices of the square matrix area are (0,0), (0,2N), (2N,0), (2N,2N), and the distance between adjacent acquisition points is the displacement step s of the image plane light field acquisition unit. In this embodiment, a 101×101 acquisition point square matrix is ​​collected, and the four vertices of the square matrix area are (0,0), (0,100), (100,0), (100,100);

[0144] g) After each move to a new collection point, the detection unit controls the spectrometer to collect the optical frequency domain waveform at the collection point. After the collection is completed, the detection unit controls the image plane light field collection unit to move its single-mode jumper input end to the next collection point, and repeats g) until the optical frequency domain waveforms of 101×101 collection points are collected;

[0145] h) Obtaining the crosstalk between the modes in the discrete mode device under test at the preset working wavelength calculated by the detection unit, the specific calculation process is as follows:

[0146] (1) For all acquisition points, the collected discrete spectra I(x, y, ω) are respectively subjected to inverse Fourier transform to obtain a series of discrete points B(x, y, t) in the time domain, where B(x, y, 0) is the self-interference term of the main mode excited by the discrete mode device, and the other time domain discrete points are the mutual interference terms between the main mode excited by the discrete mode device and other crosstalk modes. t is the time delay between other crosstalk modes and the main mode. Here, other crosstalk modes can also be called crosstalk modes. ω represents the frequency of the optical spectrum waveform.

[0147] (2) For all the acquisition points, the series of time-domain discrete points B (x, y, t) obtained are calculated as follows:

[0148]

[0149] Among them, α 2 (x, y, t) is the power ratio of other crosstalk modes to the main mode at the acquisition point (x, y). Since the mode field of the main mode is known, it can be obtained by α 2 (x, y, t) redraws the mode fields of other crosstalk modes that are delayed t from the main mode;

[0150] (3) Based on the redrawn mode fields of other crosstalk modes that have a time delay t with the main mode, other crosstalk modes excited by the discrete mode device under test can be distinguished. Different crosstalk modes have different time delays relative to the main mode.

[0151] (4) For a specific crosstalk mode B, its time delay relative to the main mode A is τ. At a certain acquisition point (x, y) on the image plane, the mode field strength of the main mode A and the crosstalk mode B is:

[0152]

[0153]

[0154] (5) The calculation formula for the inter-mode crosstalk XTB→A between the main mode A and a specific crosstalk mode B of the discrete mode device under test is:

[0155]

[0156] Repeat (4)-(5) to calculate the inter-mode crosstalk between all crosstalk modes and the main mode.

[0157] Among them, the collected LP 01 The normalized optical frequency domain waveform of the mode converter at the acquisition point (50,50) is as follows: Figure 5A As shown, the collected LP 11 The optical frequency domain waveform of the mode converter at the normalized acquisition point (50,50) is as follows: Figure 5B As shown. 01 Mode converter, the pulse-differential group delay diagram obtained after inverse Fourier transform is as follows Fig. 6A As shown; for LP 11 The pulse-differential group delay diagram obtained after the mode converter and the inverse Fourier transform is shown as follows Figure 6B As shown in Table 1, LP 01 Mode Converter LP 11 To LP 01 Inter-mode crosstalk is -37dB, LP 11 Mode Converter LP 01 To LP 11 The inter-mode crosstalk is -41dB.

[0158] Table 1

[0159] <![CDATA[LP 01 Mode Converter]]> <![CDATA[LP 11 Mode Converter]]> Inter-mode crosstalk (dB) -37 -41

[0160] The inter-mode crosstalk measurement device of the embodiment of the present invention can simply and accurately measure the inter-mode crosstalk of a discrete mode device, thus solving the problem that the inter-mode crosstalk of a discrete mode device cannot be accurately measured at present.

[0161] like Figure 7 As shown, the embodiment of the present invention also provides a method for measuring crosstalk between modes, including:

[0162] Step 701: Acquire an optical frequency domain waveform of a light field on an image plane at a light mode field, wherein the light mode field is a light field emitted by the end face of the few-mode pigtail of the discrete mode device under the action of the linearly polarized light.

[0163] The discrete mode device under test refers to a mode-related device matched with a few-mode optical fiber. The few-mode optical fiber refers to an optical fiber that supports multiple waveguide modes. The length of the few-mode pigtail is between 1m and 100m. The light field obtained above can be a light field of at least one acquisition point on the above-mentioned image plane.

[0164] Step 702: Obtain inter-mode crosstalk information of the discrete mode device under test according to the optical frequency domain waveform of the optical field.

[0165] The mode crosstalk information is the power ratio between other crosstalk modes and the main mode in the discrete mode device under test.

[0166] The inter-mode crosstalk measurement method of the embodiment of the present invention obtains the optical frequency domain waveform of the optical field on the image plane at the optical mode field, wherein the optical mode field is the optical field emitted by the end face of the few-mode pigtail of the discrete mode device under the action of the linear polarized light; and obtains the inter-mode crosstalk information of the discrete mode device under test based on the optical frequency domain waveform of the optical field. The inter-mode crosstalk measurement method of the embodiment of the present invention can simply and accurately measure the inter-mode crosstalk of the discrete mode device.

[0167] Optionally, the light field includes: a light field of at least one acquisition point;

[0168] The step of obtaining the inter-mode crosstalk information of the discrete mode device under test according to the optical frequency domain waveform of the optical field comprises:

[0169] Performing an inverse Fourier transform on the optical frequency domain waveform I(x, y, ω) of the acquisition point to obtain a time domain discrete point B(x, y, t), wherein x represents the abscissa of the acquisition point, y represents the ordinate of the acquisition point, ω represents the frequency of the optical spectrum waveform, and t represents the time delay between the crosstalk mode and the main mode of the discrete mode device under test;

[0170] Acquire, according to the time domain discrete points, the mode field strength of the main mode of the discrete mode device under test at the acquisition points and the mode field strength of the crosstalk mode excited by the discrete mode device under test at the acquisition points;

[0171] According to the mode field strength of the main mode at the acquisition point and the mode field strength of the crosstalk mode at the acquisition point, inter-mode crosstalk information between the main mode and the crosstalk mode of the discrete mode device under test is obtained.

[0172] Optionally, acquiring the mode field strength of the main mode of the discrete mode device under test at the acquisition point and the mode field strength of the crosstalk mode excited by the discrete mode device under test at the acquisition point according to the time domain discrete point includes:

[0173] According to the time domain discrete points, acquiring a power ratio of the crosstalk mode to the main mode at the collection point;

[0174] The mode field strength of the main mode of the discrete mode device under test at the collection point and the mode field strength of the crosstalk mode at the collection point are obtained according to the power ratio.

[0175] Optionally, acquiring a power ratio of the crosstalk mode to the main mode at the collection point according to the time domain discrete point includes:

[0176] By formula Acquire a power ratio of the crosstalk mode to the main mode at the collection point;

[0177] Wherein, α(x, y, τ) represents the power ratio of the crosstalk mode to the main mode at the acquisition point, τ represents the time delay between the crosstalk pattern and the main pattern.

[0178] Optionally, obtaining the mode field strength of the main mode of the discrete mode device under test at the collection point and the mode field strength of the crosstalk mode at the collection point according to the power ratio includes:

[0179] By formula Acquire the mode field strength of the main mode at the acquisition point;

[0180] By formula Obtaining the mode field strength of the crosstalk mode at the acquisition point;

[0181] Among them, I T (x, y) is the total power of the spectrum collected at the collection point on the image plane, I A (x, y) is the mode field strength of the main mode at the acquisition point, I B (x, y) is the mode field strength of the crosstalk mode at the acquisition point.

[0182] Optionally, acquiring inter-mode crosstalk information between the main mode and the crosstalk mode of the discrete mode device under test according to the mode field strength of the main mode at the collection point and the mode field strength of the crosstalk mode at the collection point includes:

[0183] By formula Obtaining the inter-mode crosstalk information;

[0184] Among them, XT B→A It represents the inter-mode crosstalk information between the main mode and the crosstalk mode, and the number of the at least one acquisition point is (2N+1)×(2N+1), where N is a natural number.

[0185] It should be noted that the inter-mode crosstalk measurement method is a measurement method applied to the above-mentioned inter-mode crosstalk measurement device. The specific implementation process of the inter-mode crosstalk measurement method has been described in detail in the above-mentioned inter-mode crosstalk measurement device embodiment. To avoid repetition, it will not be repeated here.

[0186] The method for measuring crosstalk between modes of the embodiment of the present invention obtains at least one optical field on an image plane at the optical mode field, wherein the optical mode field is the optical field emitted by the end face of the few-mode pigtail of the discrete mode device under the action of the linearly polarized light; and obtains crosstalk information between modes of the discrete mode device under test based on the optical field. The crosstalk measurement method of the embodiment of the present invention can simply and accurately measure the crosstalk between modes of the discrete mode device, and has the advantage of a large measurement dynamic range.

[0187] like Figure 8 As shown, an inter-mode crosstalk measurement device 800 according to an embodiment of the present invention includes a processor 810 and a transceiver 820, wherein:

[0188] The processor is used to obtain an optical frequency domain waveform of the light field on an image plane where the optical mode field is located, wherein the optical mode field is the light field emitted by the few-mode pigtail end face of the discrete mode device under the action of the linearly polarized light; and obtain inter-mode crosstalk information of the discrete mode device under test based on the optical frequency domain waveform of the light field.

[0189] Optionally, the light field includes: a light field of at least one acquisition point;

[0190] The processor is used to perform an inverse Fourier transform on the optical frequency domain waveform I(x, y, ω) of the acquisition point to obtain a time domain discrete point B(x, y, t), wherein x represents the abscissa of the acquisition point, y represents the ordinate of the acquisition point, ω represents the frequency of the optical spectrum waveform, and t is the time delay between the crosstalk mode and the main mode of the discrete mode device under test; based on the time domain discrete points, obtain the mode field strength of the main mode of the discrete mode device under test at the acquisition point and the mode field strength of the crosstalk mode excited by the discrete mode device under test at the acquisition point; based on the mode field strength of the main mode at the acquisition point and the mode field strength of the crosstalk mode at the acquisition point, obtain inter-mode crosstalk information between the main mode of the discrete mode device under test and the crosstalk mode.

[0191] Optionally, the processor is used to obtain a power ratio of the crosstalk mode and the main mode at the collection point according to the time domain discrete point; and obtain the mode field strength of the main mode of the discrete mode device under test at the collection point and the mode field strength of the crosstalk mode at the collection point according to the power ratio.

[0192] Optionally, the processor is further configured to: Acquire a power ratio of the crosstalk mode to the main mode at the collection point;

[0193] Wherein, α(x, y, τ) represents the power ratio of the crosstalk mode to the main mode at the acquisition point, τ represents the time delay between the crosstalk pattern and the main pattern.

[0194] Optionally, the processor is further configured to: Acquire the mode field strength of the main mode at the acquisition point;

[0195] By formula Obtaining the mode field strength of the crosstalk mode at the acquisition point;

[0196] Among them, I T (x, y) is the total power of the spectrum collected at the collection point on the image plane, I A (x, y) is the mode field strength of the main mode at the acquisition point, I B (x, y) is the mode field strength of the crosstalk mode at the acquisition point.

[0197] Optionally, the processor is further configured to: Obtaining the inter-mode crosstalk information;

[0198] Among them, XT B→A It represents the inter-mode crosstalk information between the main mode and the crosstalk mode, and the number of the at least one acquisition point is (2N+1)×(2N+1), where N is a natural number.

[0199] The inter-mode crosstalk measurement device of this embodiment can simply and accurately measure the inter-mode crosstalk of discrete mode devices, solving the current problem that the inter-mode crosstalk of discrete mode devices cannot be accurately measured.

[0200] The inter-mode crosstalk measurement device can implement all implementations of the above-mentioned inter-mode crosstalk measurement method embodiment, and will not be described again here to avoid repetition.

[0201] Another embodiment of the present invention provides an inter-mode crosstalk measurement device, such as Fig. 9As shown, it includes a transceiver 910, a processor 900, a memory 920, and a program or instruction stored in the memory 920 and executable on the processor 900; when the processor 900 executes the program or instruction, the above-mentioned inter-mode crosstalk measurement method is implemented.

[0202] The transceiver 910 is used to receive and send data under the control of the processor 900 .

[0203] Among them, Fig. 9 In the embodiment, the bus architecture may include any number of interconnected buses and bridges, specifically one or more processors represented by processor 900 and various circuits of memory represented by memory 920 are linked together. The bus architecture may also link together various other circuits such as peripherals, voltage regulators, and power management circuits, which are well known in the art and are therefore not further described herein. The bus interface provides an interface. The transceiver 910 may be a plurality of components, namely, a transmitter and a receiver, providing a unit for communicating with various other devices on a transmission medium. For different user devices, the user interface 930 may also be an interface capable of externally and internally connecting required devices, and the connected devices include but are not limited to a keypad, a display, a speaker, a microphone, a joystick, and the like.

[0204] The processor 900 is responsible for managing the bus architecture and general processing, and the memory 920 can store data used by the processor 900 when performing operations.

[0205] A readable storage medium according to an embodiment of the present invention stores a program or instruction thereon. When the program or instruction is executed by a processor, the steps in the inter-mode crosstalk measurement method as described above are implemented and the same technical effect can be achieved. To avoid repetition, it will not be described here.

[0206] The processor is a processor in the inter-mode crosstalk measurement device described in the above embodiment. The readable storage medium includes a computer readable storage medium, such as a computer read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0207] It should be further explained that the terminals described in this specification include but are not limited to smart phones, tablet computers, etc., and many of the functional components described are called modules in order to more particularly emphasize the independence of their implementation methods.

[0208] In the embodiment of the present invention, module can be implemented with software so that it can be executed by various types of processors. For example, an executable code module of an identification can include one or more physical or logical blocks of computer instructions, for example, it can be constructed as an object, process or function. Nevertheless, the executable code of the identified module does not need to be physically located together, but can include different instructions stored in different positions, and when these instructions are logically combined together, it constitutes a module and realizes the specified purpose of the module.

[0209] In fact, executable code module can be a single instruction or many instructions, and can even be distributed on a plurality of different code segments, distributed among different programs, and distributed across a plurality of memory devices. Similarly, operating data can be identified in the module, and can be implemented and organized in the data structure of any appropriate type according to any appropriate form. The operating data can be collected as a single data set, or can be distributed in different locations (including on different storage devices), and can only be present on a system or network as an electronic signal at least in part.

[0210] When a module can be implemented by software, considering the level of existing hardware technology, a person skilled in the art can build a corresponding hardware circuit to implement the corresponding function of the module that can be implemented by software without considering the cost. The hardware circuit includes a conventional very large scale integration (VLSI) circuit or gate array and existing semiconductors such as logic chips, transistors, or other discrete components. The module can also be implemented by a programmable hardware device, such as a field programmable gate array, a programmable array logic, a programmable logic device, etc.

[0211] The above exemplary embodiments are described with reference to the accompanying drawings, and many different forms and embodiments are feasible without departing from the spirit and teachings of the present invention. Therefore, the present invention should not be constructed as a limitation of the exemplary embodiments proposed herein. More specifically, these exemplary embodiments are provided so that the present invention will be perfect and complete, and the scope of the present invention will be conveyed to those who are familiar with the technology. In these figures, the component sizes and relative sizes may be exaggerated for clarity. The terms used here are only based on the purpose of describing specific exemplary embodiments and are not intended to be limiting. As used herein, unless the text clearly indicates otherwise, the singular forms "one", "an" and "the" are intended to include these multiple forms. It will be further understood that the terms "including" and / or "comprising" when used in this specification indicate the presence of the features, integers, steps, operations, components and / or components, but do not exclude the presence or increase of one or more other features, integers, steps, operations, components, components and / or their groups. Unless otherwise indicated, when stated, a range of values ​​includes the upper and lower limits of that range and any subranges therebetween.

[0212] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A device for measuring crosstalk between modes, characterized in that: include: A light source module, the light source module is connected to the input end of the discrete mode device to be tested, and is used to provide linearly polarized light; An acquisition module, the acquisition module is optically connected to the discrete mode device under test, and is used to acquire an optical frequency domain waveform of the light field on an image plane at the optical mode field, wherein the optical mode field is a light field emitted by the end face of the few-mode pigtail of the discrete mode device under test under the action of the linearly polarized light; A processing module, connected to the acquisition module, for acquiring the inter-mode crosstalk information of the discrete mode device under test according to the optical frequency domain waveform of the optical field; The light field includes: a light field of (2N+1)×(2N+1) collection points, and the coordinates of the center collection point of the (2N+1)×(2N+1) collection points are (N, N); The processing module comprises: A first acquisition subunit is used to perform an inverse Fourier transform on the optical frequency domain waveform I(x, y, ω) of the acquisition point to obtain a discrete point B(x, y, t) in the time domain, wherein x represents the abscissa of the acquisition point, y represents the ordinate of the acquisition point, ω represents the frequency of the optical spectrum waveform, and t represents the time delay between the crosstalk mode and the main mode of the discrete mode device under test; A second acquisition subunit is used to acquire the mode field strength of the main mode of the discrete mode device under test at the acquisition point and the mode field strength of the crosstalk mode excited by the discrete mode device under test at the acquisition point according to the time domain discrete point; A third acquisition subunit is used to acquire inter-mode crosstalk information between the main mode of the discrete mode device under test and the crosstalk mode according to the mode field strength of the main mode at the acquisition point and the mode field strength of the crosstalk mode at the acquisition point; Wherein, the second acquisition subunit is specifically used for: According to the time domain discrete points, acquiring a power ratio of the crosstalk mode to the main mode at the collection point; According to the power ratio, obtaining the mode field strength of the main mode of the discrete mode device under test at the collection point and the mode field strength of the crosstalk mode at the collection point; The third acquisition subunit is used to obtain the inter-mode crosstalk information between the main mode of the discrete mode device under test and the crosstalk mode through the following formula; Among them, XT B→A represents the inter-mode crosstalk information between the main mode and the crosstalk mode, I A (x, y) is the mode field strength of the main mode at the acquisition point, I B (x, y) is the mode field strength of the crosstalk mode at the collection point, and N is a natural number.

2. The inter-mode crosstalk measurement device according to claim 1, characterized in that: The light source module comprises: A light source unit, the light source unit is used to emit a wide-spectrum continuous laser; A polarizer is connected to the light source unit and the input end of the discrete mode device to be measured, respectively, and is used for converting the wide-spectrum continuous laser emitted by the light source unit into linearly polarized light.

3. The inter-mode crosstalk measurement device according to claim 1, characterized in that: The acquisition module comprises: A mode field amplification unit, the mode field amplification unit is optically connected to the discrete mode device under test, and is used to amplify the optical mode field emitted by the end face of the few-mode pigtail of the discrete mode device under test, wherein the output end of the discrete mode device under test is located at the object focus of the mode field amplification unit; An image plane light field acquisition unit, used to collect the light field on the image plane where the amplified light mode field is located, wherein the single-mode optical fiber input end of the image plane light field acquisition unit is located at the image side focal plane of the mode field amplification unit; A spectrometer is optically connected to the image plane light field acquisition unit and is used to obtain the optical frequency domain waveform of the light field.

4. The inter-mode crosstalk measurement device according to claim 3, characterized in that: The processing module is connected to the image plane light field acquisition unit and the spectrometer respectively, and is used to control the image plane light field acquisition unit to collect the light field, and obtain the inter-mode crosstalk information of the discrete mode device under test according to the optical frequency domain waveform obtained by the spectrometer.

5. The inter-mode crosstalk measurement device according to claim 4, characterized in that: The coordinates (N, N) of the central collection point of the (2N+1)×(2N+1) collection points are the coordinates of the single-mode optical fiber input end of the image plane light field collection unit on the image side focal plane when the light power collected on the spectrometer is maximum.

6. The inter-mode crosstalk measurement device according to claim 1, characterized in that: The second acquisition subunit is obtained by formula Acquire a power ratio of the crosstalk mode to the main mode at the collection point; Wherein, α(x, y, τ) represents the power ratio of the crosstalk mode to the main mode at the acquisition point, τ represents the time delay between the crosstalk pattern and the main pattern.

7. The inter-mode crosstalk measurement device according to claim 6, characterized in that: The second acquisition subunit is used to obtain Obtain the mode field strength of the main mode at the acquisition point, and use the formula Obtaining the mode field strength of the crosstalk mode at the acquisition point; Among them, I T (x, y) is the total power of the spectrum collected at the collection point on the image plane.

8. A method for measuring inter-mode crosstalk, characterized in that: include: Acquire an optical frequency domain waveform of the optical field on an image plane at the optical mode field, wherein the optical mode field is an optical field emitted by the end face of the few-mode pigtail of the discrete mode device under the action of linear polarized light; Acquiring inter-mode crosstalk information of the discrete mode device under test according to the optical frequency domain waveform of the optical field; The light field includes: a light field of (2N+1)×(2N+1) collection points, and the coordinates of the center collection point of the (2N+1)×(2N+1) collection points are (N, N); The step of obtaining the inter-mode crosstalk information of the discrete mode device under test according to the optical frequency domain waveform of the optical field comprises: Performing an inverse Fourier transform on the optical frequency domain waveform I(x, y, ω) of the acquisition point to obtain a time domain discrete point B(x, y, t), wherein x represents the abscissa of the acquisition point, y represents the ordinate of the acquisition point, ω represents the frequency of the optical spectrum waveform, and t represents the time delay between the crosstalk mode and the main mode of the discrete mode device under test; Acquire, according to the time domain discrete points, the mode field strength of the main mode of the discrete mode device under test at the acquisition points and the mode field strength of the crosstalk mode excited by the discrete mode device under test at the acquisition points; Acquire inter-mode crosstalk information between the main mode and the crosstalk mode of the discrete mode device under test according to the mode field strength of the main mode at the acquisition point and the mode field strength of the crosstalk mode at the acquisition point; Wherein, obtaining the mode field strength of the main mode of the discrete mode device under test at the acquisition point and the mode field strength of the crosstalk mode excited by the discrete mode device under test at the acquisition point according to the time domain discrete point includes: According to the time domain discrete points, acquiring a power ratio of the crosstalk mode to the main mode at the collection point; According to the power ratio, obtaining the mode field strength of the main mode of the discrete mode device under test at the collection point and the mode field strength of the crosstalk mode at the collection point; Wherein, acquiring the inter-mode crosstalk information between the main mode and the crosstalk mode of the discrete mode device under test according to the mode field strength of the main mode at the collection point and the mode field strength of the crosstalk mode at the collection point comprises: By formula Obtaining the inter-mode crosstalk information; Among them, XT B→A represents the inter-mode crosstalk information between the main mode and the crosstalk mode, I A (x, y) is the mode field strength of the main mode at the acquisition point, I B (x, y) is the mode field strength of the crosstalk mode at the collection point, and N is a natural number.

9. The method for measuring inter-mode crosstalk according to claim 8, characterized in that: The acquiring, according to the time domain discrete points, a power ratio of the crosstalk mode to the main mode at the collection point comprises: By formula Acquire a power ratio of the crosstalk mode to the main mode at the collection point; Wherein, α(x, y, τ) represents the power ratio of the crosstalk mode to the main mode at the acquisition point, τ represents the time delay between the crosstalk pattern and the main pattern.

10. The method for measuring inter-mode crosstalk according to claim 9, characterized in that: The step of obtaining the mode field strength of the main mode of the discrete mode device under test at the collection point and the mode field strength of the crosstalk mode at the collection point according to the power ratio includes: By formula Acquire the mode field strength of the main mode at the acquisition point; By formula Obtaining the mode field strength of the crosstalk mode at the collection point; Among them, I T (x, y) is the total power of the spectrum collected at the collection point on the image plane.

11. An inter-mode crosstalk measurement device, characterized in that: include: Transceiver and Processor: The processor is used to obtain an optical frequency domain waveform of the optical field on an image plane where the optical mode field is located, wherein the optical mode field is an optical field emitted by the end face of the few-mode pigtail of the discrete mode device under the action of linear polarized light; and obtain inter-mode crosstalk information of the discrete mode device under test according to the optical frequency domain waveform of the optical field; The light field includes: a light field of (2N+1)×(2N+1) collection points, and the coordinates of the center collection point of the (2N+1)×(2N+1) collection points are (N, N); The processor is used to perform inverse Fourier transform on the optical frequency domain waveform I(x, y, ω) of the acquisition point to obtain a time domain discrete point B(x, y, t), wherein x represents the abscissa of the acquisition point, y represents the ordinate of the acquisition point, ω represents the frequency of the optical spectrum waveform, and t is the time delay between the crosstalk mode and the main mode of the discrete mode device under test; according to the time domain discrete point, obtain the mode field strength of the main mode of the discrete mode device under test at the acquisition point and the mode field strength of the crosstalk mode excited by the discrete mode device under test at the acquisition point; according to the mode field strength of the main mode at the acquisition point and the mode field strength of the crosstalk mode at the acquisition point, obtain the inter-mode crosstalk information between the main mode of the discrete mode device under test and the crosstalk mode; The processor is used to obtain a power ratio of the crosstalk mode and the main mode at the collection point according to the time domain discrete point; and obtain a mode field strength of the main mode of the measured discrete mode device at the collection point and a mode field strength of the crosstalk mode at the collection point according to the power ratio; The processor is used to obtain the inter-mode crosstalk information between the main mode of the discrete mode device under test and the crosstalk mode through the following formula; Among them, XT B→A represents the inter-mode crosstalk information between the main mode and the crosstalk mode, I A (x, y) is the mode field strength of the main mode at the acquisition point, I B (x, y) is the mode field strength of the crosstalk mode at the collection point, and N is a natural number.

12. The inter-mode crosstalk measurement device according to claim 11, characterized in that: The processor is used to: By formula Acquire a power ratio of the crosstalk mode to the main mode at the collection point; Wherein, α(x, y, τ) represents the power ratio of the crosstalk mode to the main mode at the acquisition point, τ represents the time delay between the crosstalk pattern and the main pattern.

13. The inter-mode crosstalk measurement device according to claim 12, characterized in that: The processor is used to: By formula Acquire the mode field strength of the main mode at the acquisition point; By formula Obtaining the mode field strength of the crosstalk mode at the acquisition point; Among them, I T (x, y) is the total power of the spectrum collected at the collection point on the image plane.

14. An inter-mode crosstalk measurement device, comprising: A transceiver, a processor, a memory, and a program or instruction stored in the memory and executable on the processor; characterized in that when the processor executes the program or instruction, the steps in the method for measuring crosstalk between modes as described in any one of claims 8 to 10 are implemented.

15. A readable storage medium having a program or instruction stored thereon, characterized in that: When the program or instruction is executed by a processor, the steps in the method for measuring inter-mode crosstalk according to any one of claims 8 to 10 are implemented.

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