A method, device and apparatus for measuring time delay

Abstract

The present invention provides a method, device, and apparatus for measuring time delay, wherein the time delay measurement apparatus includes: a light source, an IQ modulator, and a mode converter connected in sequence; a mode controller capable of being connected to the output end of the few-mode fiber to be measured; and a signal measurement sub-device; the signal measurement sub-device includes: a light detector connected to the mode controller, and a calculation unit connected to the light detector via a signal collector; wherein the mode converter is capable of being connected to the input end of the few-mode fiber to be measured; the IQ modulator is also connected to a signal generator; the IQ modulator modulates the signal generated by the signal generator onto the linearly polarized laser light emitted by the light source to form a modulated single-sideband optical signal; and the calculation unit is capable of determining the differential mode delay information within the degenerate mode of the few-mode fiber to be measured based on the signal collected by the signal collector. This solution solves the problem in the prior art of being unable to accurately measure the differential mode delay within the degenerate mode.

Description

Technical Field

[0001] The present invention relates to the field of information measurement technology, and in particular to a delay measurement method, device and equipment. Background Art

[0002] With the continuous increase in network users and the emergence of new network data services, the demand for network capacity is growing. Because common optical multiplexing dimensions (such as time, wavelength, polarization, and multi-level modulation) are facing potential bottlenecks, current optical communication systems based on standard single-mode fiber are unable to meet the booming network capacity demand. However, the modes in few-mode fiber (FMF) have attracted widespread attention as a new optical multiplexing dimension. Ideally, the modes are mutually orthogonal and can be used as independent channels. By combining these modes with traditional time, wavelength, polarization, and multi-level modulation formats, the system's transmission capacity can be greatly increased. In the future, FMF will be widely used in key scenarios such as slicing packet networks (SPNs), optical transport networks (OTNs), passive optical networks (PONs), 5G fronthaul, and data center interconnects (DCIs). Therefore, studying and testing the mode-related parameters in FMF is crucial for monitoring system performance.

[0003] Specifically, due to weak guidance, the eigenvector modes supported by few-mode fiber can become degenerate. This means that eigenvector modes with similar effective refractive indices degenerate into a single degenerate mode. In mode-division multiplexing (MDM) fiber transmission systems, degenerate modes are typically used as channel units. This means that the eigenvector modes comprising the same degenerate mode carry the same signal in the fiber.

[0004] However, each eigenvector mode within the same degenerate mode still has slight differences in effective refractive index and propagation velocity, which accumulates delay during transmission. This in turn causes signal broadening and intersymbol interference (ISI), resulting in signal quality degradation and impacting network transmission performance. This phenomenon is called intra-degenerate-mode differential mode delay (IDM-DMD). IDM-DMD is a critical parameter affecting system performance and stability.

[0005] However, there is no measurement solution for the intra-degenerate mode differential mode delay in the prior art, and the intra-degenerate mode differential mode delay cannot be accurately measured. Summary of the Invention

[0006] The object of the present invention is to provide a method, apparatus and device for measuring time delay, so as to solve the problem in the prior art that the time delay of the differential mode in the degenerate mode cannot be accurately measured.

[0007] In order to solve the above technical problems, an embodiment of the present invention provides a delay measurement device, including:

[0008] A light source, an IQ modulator and a mode converter connected in sequence;

[0009] and, a mode controller capable of being connected to the output end of the few-mode optical fiber to be tested;

[0010] and a signal measuring sub-device; the signal measuring sub-device comprising: a light detector connected to the mode controller, and a calculation unit connected to the light detector via a signal collector;

[0011] The mode converter can be connected to the input end of the few-mode optical fiber to be tested; the IQ modulator is also connected to a signal generator; the IQ modulator modulates the signal generated by the signal generator onto the linearly polarized laser emitted by the light source to form a modulated single-sideband optical signal;

[0012] The calculation unit can determine the differential mode delay information within the degenerate mode of the few-mode optical fiber to be tested based on the signal collected by the signal collector.

[0013] Optionally, the signal generator is a sine wave generator, and the device further comprises: an optical power splitter provided between the mode controller and the optical detector, and a mode component discriminator connected to the mode controller, the optical power splitter and the signal collector respectively;

[0014] Alternatively, the signal generator is a linear frequency modulation wave generator, and the signal collector is a frequency domain electrical signal collector.

[0015] An embodiment of the present invention further provides a delay measurement method, which is applied to the above-mentioned delay measurement device. The method includes:

[0016] The signal generated by the signal generator is modulated by an IQ modulator onto the linearly polarized laser emitted by the light source to form a modulated single-sideband optical signal;

[0017] Using a mode converter to convert the fundamental mode in the few-mode optical fiber to be tested into a degenerate mode to be tested, and sending the single-sideband optical signal to the few-mode optical fiber to be tested;

[0018] Using a mode controller to adjust the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested, obtain an adjusted optical signal, and transmit it to a light detector;

[0019] Using the light detector and the signal collector, convert part or all of the adjusted light signal into a digital signal and transmit it to the computing unit;

[0020] The calculation unit is used to obtain, according to the digital signal, the intra-degenerate mode differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested.

[0021] Optionally, the degenerate mode intra-differential mode delay information includes: at least one of a degenerate mode intra-differential mode delay value and a degenerate mode intra-differential mode delay coefficient.

[0022] Optionally, the signal generator is a sine wave generator;

[0023] The method of adjusting the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested by using the mode controller to obtain the adjusted optical signal and transmitting the adjusted optical signal to the optical detector includes:

[0024] Using a mode controller to adjust the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested, obtain an adjusted optical signal, and transmit it to an optical power splitter;

[0025] Using the optical power splitter to divide the adjusted optical signal, and sending the optical signal with higher power to the optical detector, and sending the optical signal with lower power to the mode component discriminator;

[0026] Determining whether the eigenmode combination ratio is in an equal state using the mode component identifier, and if the eigenmode combination ratio is not in an equal state, sending the identification result to the mode controller, returning to execute the step of adjusting the eigenmode combination ratio of the optical signal output by the few-mode optical fiber to be tested using the mode controller until the eigenmode combination ratio is in an equal state; and sending the identification result to the mode controller and the signal collector if the eigenmode combination ratio is in an equal state;

[0027] The method of converting part of the adjusted optical signal into a digital signal by using the optical detector and the signal collector includes:

[0028] Using the light detector to convert the high-power optical signal into an electrical signal and send it to a signal collector;

[0029] The signal collector is used to collect the time domain electrical signal corresponding to the electrical signal transmitted by the light detector according to the identification result, and convert it into a digital signal.

[0030] Optionally, the digital signal includes an optical power signal value P;

[0031] The obtaining, using the calculation unit, according to the digital signal, the differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested includes:

[0032] Using the calculation unit, according to the optical power signal value P, using formula 1, obtain the degenerate mode differential mode delay value of the few-mode optical fiber to be tested in the degenerate mode to be tested;

[0033] Wherein, the formula 1 is:

[0034] The Δτ IDM-DMD represents the differential mode delay value in the degenerate mode; π represents the pi ratio; f1 represents the frequency of the sine wave generated by the sine wave generator; P0 represents the output power of the light source; IL represents the optical power loss from the IQ modulator to the optical power splitter.

[0035] Optionally, the signal generator is a linear frequency modulation wave generator;

[0036] The method of converting all the adjusted optical signals into digital signals by using the optical detector and the signal collector includes:

[0037] Using the light detector to convert all the adjusted optical signals into electrical signals and send them to a signal collector;

[0038] Using the signal collector to collect the frequency domain electrical signal corresponding to the electrical signal transmitted by the light detector, and converting it into a digital signal;

[0039] The method of adjusting the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested by using the mode controller to obtain the adjusted optical signal and transmitting the adjusted optical signal to the optical detector includes:

[0040] The method of adjusting the eigenmode combination ratio of the optical signal output by the few-mode optical fiber to be tested by using the mode controller is performed at least once to obtain an adjusted optical signal, and transmit the adjusted optical signal to the optical detector; until the frequency domain electrical signal reaches a peak value.

[0041] Optionally, the digital signal includes a frequency f2 corresponding to the peak value;

[0042] The obtaining, using the calculation unit, according to the digital signal, the differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested includes:

[0043] Using the calculation unit, according to the frequency f2, and using Formula 2, obtain the degenerate mode differential mode delay value of the few-mode optical fiber to be tested in the degenerate mode to be tested;

[0044] Wherein, the formula 2 is:

[0045] The Δτ IDM-DMD represents the differential mode delay value in the degenerate mode; and γ represents the sweep speed of the linear frequency modulation wave generator.

[0046] Optionally, the obtaining, by the calculation unit, according to the digital signal, the differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested further includes:

[0047] Using the calculation unit, according to the intra-degenerate mode differential mode delay value, using Formula 3, obtain the intra-degenerate mode differential mode delay coefficient of the few-mode optical fiber to be tested in the degenerate mode to be tested;

[0048] Wherein, the formula three is:

[0049] The C IDM-DMD represents the differential mode delay coefficient in the degenerate mode; the Δτ IDM-DMD represents the differential mode delay value in the degenerate mode; and L represents the length of the few-mode optical fiber to be tested.

[0050] An embodiment of the present invention further provides a delay measurement device, which is applied to the above-mentioned delay measurement device, and the device includes:

[0051] The first modulation module is used to modulate the signal generated by the signal generator onto the linearly polarized laser emitted by the light source using an IQ modulator to form a modulated single-sideband optical signal;

[0052] a conversion and transmission module, configured to convert the fundamental mode in the few-mode optical fiber to be tested into a degenerate mode to be tested using a mode converter, and to send the single-sideband optical signal to the few-mode optical fiber to be tested;

[0053] an adjusting transmission module, configured to adjust the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested by using a mode controller, obtain an adjusted optical signal, and transmit the adjusted optical signal to a light detector;

[0054] a conversion and transmission module, configured to convert part or all of the adjusted optical signal into a digital signal using the optical detector and the signal collector, and transmit the digital signal to the computing unit;

[0055] The first processing module is configured to obtain, by using the calculation unit and according to the digital signal, the intra-degenerate mode differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested.

[0056] Optionally, the degenerate mode intra-differential mode delay information includes: at least one of a degenerate mode intra-differential mode delay value and a degenerate mode intra-differential mode delay coefficient.

[0057] Optionally, the signal generator is a sine wave generator;

[0058] The method of adjusting the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested by using the mode controller to obtain the adjusted optical signal and transmitting the adjusted optical signal to the optical detector includes:

[0059] Using a mode controller to adjust the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested, obtain an adjusted optical signal, and transmit it to an optical power splitter;

[0060] Using the optical power splitter to divide the adjusted optical signal, and sending the optical signal with higher power to the optical detector, and sending the optical signal with lower power to the mode component discriminator;

[0061] Determining whether the eigenmode combination ratio is in an equal state using the mode component identifier, and if the eigenmode combination ratio is not in an equal state, sending the identification result to the mode controller, returning to execute the step of adjusting the eigenmode combination ratio of the optical signal output by the few-mode optical fiber to be tested using the mode controller until the eigenmode combination ratio is in an equal state; and sending the identification result to the mode controller and the signal collector if the eigenmode combination ratio is in an equal state;

[0062] The method of converting part of the adjusted optical signal into a digital signal by using the optical detector and the signal collector includes:

[0063] Using the light detector to convert the high-power optical signal into an electrical signal and send it to a signal collector;

[0064] The signal collector is used to collect the time domain electrical signal corresponding to the electrical signal transmitted by the light detector according to the identification result, and convert it into a digital signal.

[0065] Optionally, the digital signal includes an optical power signal value P;

[0066] The obtaining, using the calculation unit, according to the digital signal, the differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested includes:

[0067] Using the calculation unit, according to the optical power signal value P, using formula 1, obtain the degenerate mode differential mode delay value of the few-mode optical fiber to be tested in the degenerate mode to be tested;

[0068] Wherein, the formula 1 is:

[0069] The Δτ IDM-DMD represents the differential mode delay value in the degenerate mode; π represents the pi ratio; f1 represents the frequency of the sine wave generated by the sine wave generator; P0 represents the output power of the light source; IL represents the optical power loss from the IQ modulator to the optical power splitter.

[0070] Optionally, the signal generator is a linear frequency modulation wave generator;

[0071] The method of converting all the adjusted optical signals into digital signals by using the optical detector and the signal collector includes:

[0072] Using the light detector to convert all the adjusted optical signals into electrical signals and send them to a signal collector;

[0073] Using the signal collector to collect the frequency domain electrical signal corresponding to the electrical signal transmitted by the light detector, and converting it into a digital signal;

[0074] The method of adjusting the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested by using the mode controller to obtain the adjusted optical signal and transmitting the adjusted optical signal to the optical detector includes:

[0075] The method of adjusting the eigenmode combination ratio of the optical signal output by the few-mode optical fiber to be tested by using the mode controller is performed at least once to obtain an adjusted optical signal, and transmit the adjusted optical signal to the optical detector; until the frequency domain electrical signal reaches a peak value.

[0076] Optionally, the digital signal includes a frequency f2 corresponding to the peak value;

[0077] The obtaining, using the calculation unit, according to the digital signal, the differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested includes:

[0078] Using the calculation unit, according to the frequency f2, and using Formula 2, obtain the degenerate mode differential mode delay value of the few-mode optical fiber to be tested in the degenerate mode to be tested;

[0079] Wherein, the formula 2 is:

[0080] The Δτ IDM-DMDrepresents the differential mode delay value in the degenerate mode; and γ represents the sweep speed of the linear frequency modulation wave generator.

[0081] Optionally, the obtaining, by the calculation unit, according to the digital signal, the differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested further includes:

[0082] Using the calculation unit, according to the intra-degenerate mode differential mode delay value, using Formula 3, obtain the intra-degenerate mode differential mode delay coefficient of the few-mode optical fiber to be tested in the degenerate mode to be tested;

[0083] Wherein, the formula three is:

[0084] The C IDM-DMD represents the differential mode delay coefficient in the degenerate mode; the Δτ IDM-DMD represents the differential mode delay value in the degenerate mode; and L represents the length of the few-mode optical fiber to be tested.

[0085] An embodiment of the present invention further provides a delay measurement device, comprising the components included in the above-mentioned delay measurement device, wherein the delay measurement device further comprises: a processor and a transceiver;

[0086] The processor is used to modulate the signal generated by the signal generator onto the linearly polarized laser emitted by the light source using an IQ modulator to form a modulated single-sideband optical signal;

[0087] Using a mode converter to convert the fundamental mode in the few-mode optical fiber to be tested into a degenerate mode to be tested, and sending the single-sideband optical signal to the few-mode optical fiber to be tested;

[0088] Using a mode controller to adjust the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested, obtain an adjusted optical signal, and transmit it to a light detector;

[0089] Using the light detector and the signal collector, convert part or all of the adjusted light signal into a digital signal and transmit it to the computing unit;

[0090] The calculation unit is used to obtain, according to the digital signal, the intra-degenerate mode differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested.

[0091] Optionally, the degenerate mode intra-differential mode delay information includes: at least one of a degenerate mode intra-differential mode delay value and a degenerate mode intra-differential mode delay coefficient.

[0092] Optionally, the signal generator is a sine wave generator;

[0093] The method of adjusting the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested by using the mode controller to obtain the adjusted optical signal and transmitting the adjusted optical signal to the optical detector includes:

[0094] Using a mode controller to adjust the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested, obtain an adjusted optical signal, and transmit it to an optical power splitter;

[0095] Using the optical power splitter to divide the adjusted optical signal, and sending the optical signal with higher power to the optical detector, and sending the optical signal with lower power to the mode component discriminator;

[0096] Determining whether the eigenmode combination ratio is in an equal state using the mode component identifier, and if the eigenmode combination ratio is not in an equal state, sending the identification result to the mode controller, returning to execute the step of adjusting the eigenmode combination ratio of the optical signal output by the few-mode optical fiber to be tested using the mode controller until the eigenmode combination ratio is in an equal state; and sending the identification result to the mode controller and the signal collector if the eigenmode combination ratio is in an equal state;

[0097] The method of converting part of the adjusted optical signal into a digital signal by using the optical detector and the signal collector includes:

[0098] Using the light detector to convert the high-power optical signal into an electrical signal and send it to a signal collector;

[0099] The signal collector is used to collect the time domain electrical signal corresponding to the electrical signal transmitted by the light detector according to the identification result, and convert it into a digital signal.

[0100] Optionally, the digital signal includes an optical power signal value P;

[0101] The obtaining, using the calculation unit, according to the digital signal, the differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested includes:

[0102] Using the calculation unit, according to the optical power signal value P, using formula 1, obtain the degenerate mode differential mode delay value of the few-mode optical fiber to be tested in the degenerate mode to be tested;

[0103] Wherein, the formula 1 is:

[0104] The Δτ IDM-DMDrepresents the differential mode delay value in the degenerate mode; π represents the pi ratio; f1 represents the frequency of the sine wave generated by the sine wave generator; P0 represents the output power of the light source; IL represents the optical power loss from the IQ modulator to the optical power splitter.

[0105] Optionally, the signal generator is a linear frequency modulation wave generator;

[0106] The method of converting all the adjusted optical signals into digital signals by using the optical detector and the signal collector includes:

[0107] Using the light detector to convert all the adjusted optical signals into electrical signals and send them to a signal collector;

[0108] Using the signal collector to collect the frequency domain electrical signal corresponding to the electrical signal transmitted by the light detector, and converting it into a digital signal;

[0109] The method of adjusting the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested by using the mode controller to obtain the adjusted optical signal and transmitting the adjusted optical signal to the optical detector includes:

[0110] The method of adjusting the eigenmode combination ratio of the optical signal output by the few-mode optical fiber to be tested by using the mode controller is performed at least once to obtain an adjusted optical signal, and transmit the adjusted optical signal to the optical detector; until the frequency domain electrical signal reaches a peak value.

[0111] Optionally, the digital signal includes a frequency f2 corresponding to the peak value;

[0112] The obtaining, using the calculation unit, according to the digital signal, the differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested includes:

[0113] Using the calculation unit, according to the frequency f2, and using Formula 2, obtain the degenerate mode differential mode delay value of the few-mode optical fiber to be tested in the degenerate mode to be tested;

[0114] Wherein, the formula 2 is:

[0115] The Δτ IDM-DMD represents the differential mode delay value in the degenerate mode; and γ represents the sweep speed of the linear frequency modulation wave generator.

[0116] Optionally, the obtaining, by the calculation unit, according to the digital signal, the differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested further includes:

[0117] Using the calculation unit, according to the intra-degenerate mode differential mode delay value, using Formula 3, obtain the intra-degenerate mode differential mode delay coefficient of the few-mode optical fiber to be tested in the degenerate mode to be tested;

[0118] Wherein, the formula three is:

[0119] The C IDM-DMD represents the differential mode delay coefficient in the degenerate mode; the Δτ IDM-DMD represents the differential mode delay value in the degenerate mode; and L represents the length of the few-mode optical fiber to be tested.

[0120] An embodiment of the present invention further provides a delay measurement device, comprising a memory, a processor, and a program stored in the memory and executable on the processor; the processor implements the above-mentioned delay measurement method when executing the program.

[0121] An embodiment of the present invention further provides a readable storage medium storing a program, which implements the steps in the above-mentioned delay measurement method when executed by a processor.

[0122] The beneficial effects of the above technical solution of the present invention are as follows:

[0123] In the above scheme, the delay measurement device is provided with a light source, an IQ modulator and a mode converter connected in sequence; and a mode controller that can be connected to the output end of the few-mode optical fiber to be measured; and a signal measurement sub-device; the signal measurement sub-device includes: a light detector connected to the mode controller, and a calculation unit connected to the light detector through a signal collector; wherein, the mode converter can be connected to the input end of the few-mode optical fiber to be measured; the IQ modulator is also connected to a signal generator; the IQ modulator modulates the signal generated by the signal generator onto the linearly polarized laser emitted by the light source to form a modulated single-sideband optical signal; the The calculation unit can determine the intra-degenerate mode differential mode delay information of the few-mode optical fiber to be tested based on the signal collected by the signal collector; it can separate the intra-degenerate mode differential mode delay and chromatic dispersion, and quickly and accurately measure the intra-degenerate mode differential mode delay information, thereby achieving simple, fast and accurate measurement of the intra-degenerate mode differential mode delay information; in addition, this solution can reduce the number of times the few-mode optical fiber is disassembled and assembled, and debugging is simple. The intra-degenerate mode differential mode delay information of the measured degenerate mode can be obtained after one debugging, which greatly reduces the workload and has a high degree of automation; and it effectively solves the problem in the prior art of being unable to accurately measure the intra-degenerate mode differential mode delay. BRIEF DESCRIPTION OF THE DRAWINGS

[0124] Figure 1 The structure of the delay measurement device according to the embodiment of the present invention is shown as follows: Figure 1 ;

[0125] Figure 2 Schematic diagram of the delay measurement method according to an embodiment of the present invention;

[0126] Figure 3 The specific implementation structure of the delay measurement device of the embodiment of the present invention is shown as follows Figure 1 ;

[0127] Figure 4 The specific implementation structure of the delay measurement device of the embodiment of the present invention is shown as follows Figure 2 ;

[0128] Figure 5 The specific implementation structure of the delay measurement device of the embodiment of the present invention is shown as follows Figure 3 ;

[0129] Figure 6 The specific implementation structure of the delay measurement device of the embodiment of the present invention is shown as follows Figure 4 ;

[0130] Figure 7 Schematic diagram of the structure of a delay measurement device according to an embodiment of the present invention;

[0131] Figure 8 The structure of the delay measurement device according to the embodiment of the present invention is shown as follows: Figure 2 . DETAILED DESCRIPTION

[0132] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0133] The present invention aims to solve the problem that the existing technology cannot accurately measure the differential mode delay in the degenerate mode, and provides a delay measurement device, such as Figure 1 As shown, including:

[0134] A light source 1, an IQ modulator 2 and a mode converter 3 connected in sequence;

[0135] and a mode controller 5 capable of being connected to the output end of the few-mode optical fiber 4 to be tested;

[0136] and a signal measuring sub-device; the signal measuring sub-device comprises: a light detector 6 connected to the mode controller 5, and a calculation unit 8 connected to the light detector 6 via a signal collector 7;

[0137] The mode converter 3 can be connected to the input end of the few-mode optical fiber 4 to be tested; the IQ modulator 2 is also connected to the signal generator 9; the IQ modulator 2 modulates the signal generated by the signal generator 9 onto the linearly polarized laser emitted by the light source 1 to form a modulated single-sideband optical signal;

[0138] The calculation unit 8 can determine the differential mode delay information within the degenerate mode of the few-mode optical fiber 4 to be tested based on the signal collected by the signal collector 7 .

[0139] The measured few-mode fiber may also be referred to as the tested few-mode fiber, without limitation. The IQ modulator uses single-sideband modulation to suppress chromatic dispersion of the signal transmitted to the measured few-mode fiber during transmission. This device can be disconnected from the few-mode fiber if delay measurement is not required; for example, neither the mode controller nor the mode converter is connected to the few-mode fiber. An IQ modulator refers to an in-phase and quadrature-phase modulator.

[0140] The delay measurement device provided by the embodiment of the present invention is provided with a light source, an IQ modulator and a mode converter connected in sequence; and a mode controller that can be connected to the output end of the few-mode optical fiber to be measured; and a signal measurement sub-device; the signal measurement sub-device includes: a light detector connected to the mode controller, and a calculation unit connected to the light detector through a signal collector; wherein the mode converter can be connected to the input end of the few-mode optical fiber to be measured; the IQ modulator is also connected to a signal generator; the IQ modulator modulates the signal generated by the signal generator onto the linearly polarized laser emitted by the light source to form a modulated single-sideband optical signal; The calculation unit can determine the intra-degenerate mode differential mode delay information of the few-mode optical fiber to be tested based on the signal collected by the signal collector; it can separate the intra-degenerate mode differential mode delay and chromatic dispersion, and quickly and accurately measure the intra-degenerate mode differential mode delay information, thereby achieving simple, fast and accurate measurement of the intra-degenerate mode differential mode delay information; in addition, this solution can reduce the number of times the few-mode optical fiber is disassembled and assembled, and debugging is simple. The intra-degenerate mode differential mode delay information of the measured degenerate mode can be obtained after one debugging, which greatly reduces the workload and has a high degree of automation; and it effectively solves the problem in the prior art of being unable to accurately measure the intra-degenerate mode differential mode delay.

[0141] Wherein, the signal generator is a sine wave generator, and the device further comprises: an optical power splitter provided between the mode controller and the optical detector, and a mode component discriminator connected to the mode controller, the optical power splitter, and the signal collector respectively; or, the signal generator is a linear frequency modulation wave generator, and the signal collector is a frequency domain electrical signal collector. For details, please refer to Figures 3 to 6 .

[0142] Specifically, the optical power splitter may be a 90:10 optical power splitter.

[0143] The embodiment of the present invention also provides a delay measurement method, which is applied to the above-mentioned delay measurement device, such as Figure 2 As shown, the method includes:

[0144] Step 21: Using an IQ modulator, the signal generated by the signal generator is modulated onto the linearly polarized laser light emitted by the light source to form a modulated single-sideband optical signal;

[0145] Step 22: using a mode converter to convert the fundamental mode in the few-mode optical fiber to be tested into a degenerate mode to be tested, and sending the single-sideband optical signal to the few-mode optical fiber to be tested;

[0146] Step 23: using a mode controller to adjust the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested, obtain an adjusted optical signal, and transmit it to a light detector;

[0147] Step 24: using the light detector and signal collector, convert part or all of the adjusted light signal into a digital signal, and transmit it to a computing unit;

[0148] Step 25: using the calculation unit, according to the digital signal, obtaining the intra-degenerate mode differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested.

[0149] In step 24, "using the optical detector and the signal collector to convert part or all of the adjusted optical signal into a digital signal" may specifically include: using the optical detector to convert part or all of the adjusted optical signal into an electrical signal, and using the signal collector to convert the electrical signal obtained by the optical detector into a digital signal.

[0150] The delay measurement method provided by the embodiment of the present invention uses an IQ modulator to modulate the signal generated by the signal generator onto the linearly polarized laser emitted by the light source to form a modulated single-sideband optical signal; uses a mode converter to convert the fundamental mode in the few-mode optical fiber to be measured into a degenerate mode to be measured, and sends the single-sideband optical signal to the few-mode optical fiber to be measured; uses a mode controller to adjust the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be measured to obtain an adjusted optical signal, and transmits it to a light detector; uses the light detector and a signal collector to convert part or all of the adjusted optical signal into a digital signal, and transmits it to a computing unit; uses the computing unit to obtain a digital signal. According to the digital signal, the degenerate mode intra-differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested is obtained; the degenerate mode intra-differential mode delay and chromatic dispersion can be separated, and the degenerate mode intra-differential mode delay information can be quickly and accurately measured, thereby achieving simple, fast and accurate measurement of the degenerate mode intra-differential mode delay information; in addition, the present solution can reduce the number of times the few-mode optical fiber is disassembled and assembled, and the debugging is simple. The degenerate mode intra-differential mode delay information to be tested can be obtained in one debugging, which greatly reduces the workload and has a high degree of automation; and the present solution effectively solves the problem in the prior art of being unable to accurately measure the degenerate mode intra-differential mode delay.

[0151] The intra-degenerate mode differential mode delay information includes at least one of a degenerate mode intra-differential mode delay value and a degenerate mode intra-differential mode delay coefficient.

[0152] In an embodiment of the present invention, the signal generator may be a sine wave generator; the mode controller is used to adjust the eigenmode combination ratio of the optical signal output by the few-mode optical fiber to be tested, the adjusted optical signal is obtained, and the optical signal is transmitted to the optical detector, including: using the mode controller to adjust the eigenmode combination ratio of the optical signal output by the few-mode optical fiber to be tested, the adjusted optical signal is obtained, and the optical signal is transmitted to the optical power splitter; using the optical power splitter to divide the adjusted optical signal, and sending the optical signal with larger power to the optical detector, and sending the optical signal with smaller power to the mode component discriminator; using the mode component discriminator to determine whether the eigenmode combination ratio is in an equal state, and when the eigenmode combination ratio is not in an equal state When the eigenmode combination ratio is in an equal state, the identification result is sent to the mode controller, and the method returns to execute the method of adjusting the eigenmode combination ratio of the optical signal output by the tested few-mode optical fiber by using the mode controller until the eigenmode combination ratio is in an equal state; when the eigenmode combination ratio is in an equal state, the identification result is sent to the mode controller and the signal collector; the method of converting part of the adjusted optical signal into a digital signal by using the optical detector and the signal collector includes: converting the optical signal with higher power into an electrical signal by using the optical detector, and sending it to the signal collector; and collecting the time domain electrical signal corresponding to the electrical signal transmitted by the optical detector according to the identification result by using the signal collector, and converting it into a digital signal.

[0153] Regarding “dividing the adjusted optical signal using the optical power splitter”, it may specifically include: using the optical power splitter to divide the adjusted optical signal according to a first power ratio. Specifically, the first power ratio may be 90:10.

[0154] The digital signal includes an optical power signal value P; and using the calculation unit to obtain, according to the digital signal, the differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested, includes: using the calculation unit to obtain, according to the optical power signal value P, the differential mode delay value of the few-mode optical fiber to be tested in the degenerate mode to be tested in the degenerate mode to be tested using Formula 1; wherein Formula 1 is: The Δτ IDM-DMD represents the differential mode delay value in the degenerate mode; π represents the pi ratio; f1 represents the frequency of the sine wave generated by the sine wave generator; P0 represents the output power of the light source; IL represents the optical power loss from the IQ modulator to the optical power splitter.

[0155] In an embodiment of the present invention, the signal generator may be a linear frequency modulation wave generator; the use of the optical detector and the signal collector to convert all the adjusted optical signals into digital signals includes: using the optical detector to convert all the adjusted optical signals into electrical signals, and sending them to the signal collector; using the signal collector to collect the frequency domain electrical signal corresponding to the electrical signal transmitted by the optical detector, and converting it into a digital signal; using the mode controller to adjust the eigenmode combination ratio of the optical signal output by the few-mode optical fiber to be tested, obtain the adjusted optical signal, and transmit it to the optical detector, including: executing at least once the use of the mode controller to adjust the eigenmode combination ratio of the optical signal output by the few-mode optical fiber to be tested, obtain the adjusted optical signal, and transmit it to the optical detector; until the frequency domain electrical signal reaches a peak value.

[0156] The “peak value” may specifically refer to the maximum value in the frequency domain electrical signal corresponding to the electrical signal emitted by the light detector.

[0157] The digital signal includes a frequency f2 corresponding to the peak; and using the calculation unit to obtain, according to the digital signal, the differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested, includes: using the calculation unit to obtain, according to the frequency f2, the differential mode delay value of the few-mode optical fiber to be tested in the degenerate mode to be tested in the degenerate mode to be tested using Formula 2; wherein Formula 2 is: The Δτ IDM-DMD represents the differential mode delay value in the degenerate mode; and γ represents the sweep speed of the linear frequency modulation wave generator.

[0158] In an embodiment of the present invention, the method of obtaining, using the calculation unit, the intra-degenerate mode differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested according to the digital signal further includes: obtaining, using the calculation unit, the intra-degenerate mode differential mode delay coefficient of the few-mode optical fiber to be tested in the degenerate mode to be tested according to the intra-degenerate mode differential mode delay value using Formula 3; wherein Formula 3 is: The C IDM-DMD represents the differential mode delay coefficient in the degenerate mode; the Δτ IDM-DMD represents the differential mode delay value in the degenerate mode; and L represents the length of the few-mode optical fiber to be tested.

[0159] The delay measurement device and method provided in the embodiments of the present invention are described below by way of example. The delay measurement device may also be referred to as a delay measurement apparatus, and the following description will be based on the delay measurement apparatus.

[0160] To address the above-mentioned technical issues, embodiments of the present invention provide a delay measurement device and method. Specifically, taking into account that, like the fundamental mode in ordinary single-mode fiber, each degenerate mode in a few-mode fiber will also produce chromatic dispersion (CD) due to the material dispersion and waveguide dispersion of the fiber waveguide, and will also accumulate delay during transmission, thereby causing signal broadening. Among them, the differential mode delay and chromatic dispersion within the degenerate mode are two parameters that cause the same damage but have different origins. This solution uses technical means to separate the differential mode delay and chromatic dispersion within the degenerate mode, and accurately measures the parameter characteristics of the differential mode delay within the degenerate mode, which is of great significance for evaluating the performance of mode-division transmission systems.

[0161] It can also be understood that this solution involves a device and method for measuring the differential mode delay within a degenerate mode in a few-mode optical fiber, which can simply and accurately measure the differential mode delay within the degenerate mode (corresponding to the above-mentioned differential mode delay value within the degenerate mode) and its coefficient (corresponding to the above-mentioned differential mode delay coefficient within the degenerate mode), so as to achieve the purpose of separating the differential mode delay within the degenerate mode from the chromatic dispersion and accurately measuring the differential mode delay within the degenerate mode. It has the advantages of simplicity, fast measurement speed, and accurate measurement.

[0162] Specifically, the embodiments of the present invention address the problem of measuring differential mode delay within a degenerate mode in a few-mode fiber and provide two devices and methods for measuring differential mode delay within a degenerate mode in a few-mode fiber, as follows:

[0163] Part 1, the solution 1 adopted by the present invention to solve the above-mentioned problem is:

[0164] (1) Provided is a device for measuring differential mode delay in a degenerate mode of a few-mode optical fiber based on single-sideband sinusoidal modulation, comprising a light source, an IQ modulator, a sine wave generator (a specific implementation example of a signal generator), a mode converter, a mode controller, a 90:10 optical power splitter (a specific implementation example of an optical power splitter), a light detector, a signal collector, and a calculation unit; the specific structure can be found in Figure 3 It should be noted that in this solution, chromatic dispersion can be suppressed through single-sideband modulation, so there is no influence of chromatic dispersion after it comes out of the IQ modulator. The same applies to the following solutions.

[0165] (2) Provide a method for measuring differential mode delay within a degenerate mode in a few-mode optical fiber based on single-sideband sinusoidal modulation, which applies the above-mentioned differential mode delay measurement device within a degenerate mode in a few-mode optical fiber based on single-sideband sinusoidal modulation.

[0166] like Figure 3As shown, the differential mode delay measurement device in the degenerate mode of the few-mode optical fiber based on single-sideband sinusoidal modulation: the light source, IQ modulator, mode converter, mode controller, 90:10 optical power splitter and optical detector are arranged in sequence on the optical path; the mode component discriminator is optically connected to the 90:10 optical power splitter; the sine wave generator is electrically connected to the IQ modulator; the signal collector is electrically connected to the optical detector; the calculation unit is connected to the digital signal of the signal collector; the light source is used to generate linearly polarized laser; the sine wave generator is used to generate a sine wave radio frequency signal of a specific frequency; the IQ modulator is used to modulate the sine wave radio frequency signal generated by the sine wave generator onto the linearly polarized laser emitted by the light source to form a modulated single-sideband light The invention relates to a method for transmitting a signal to a single-mode optical fiber; the mode converter is used to convert the fundamental mode in the single-mode optical fiber into a specific degenerate mode (corresponding to the above-mentioned degenerate mode to be measured) in the few-mode optical fiber to be measured; the mode controller is used to control the change of the intrinsic mode combination ratio of the degenerate mode; the 90:10 optical power splitter is used to split the optical signal into two paths with a power ratio of 90:10; the mode component discriminator is used to identify the intrinsic mode combination ratio of the optical signal and can notify the mode controller and the signal collector of the identification result; the optical detector is used to convert the optical signal into an electrical signal; the signal collector is used to collect the electrical signal as a digital signal; the calculation unit is used to obtain the digital signal collected by the signal collector and calculate the degenerate mode intra-differential mode delay of the degenerate mode to be measured in the few-mode optical fiber to be measured. It should be noted that the "90:10 optical power splitter" can also be other ratios and is not limited here; the same applies to the following schemes. In this scheme, the mode converter can be used to purely excite the specific degenerate mode to be measured in the few-mode optical fiber to achieve the measurement of its intra-mode differential mode delay; the same applies to the following schemes.

[0167] Optionally, the device for measuring differential mode delay in a degenerate mode of a few-mode optical fiber based on single-sideband sinusoidal modulation has an adjustable light source operating wavelength, spectrum width, and laser power, and is used to provide narrow-spectrum continuous laser light. The light source operating wavelength range is continuously adjustable between 400-1700nm, the laser linewidth is less than 5MHz, and the laser power is continuously adjustable between 0-1W; its IQ modulator can be a lithium niobate modulator, a silicon-based modulator, an indium phosphide modulator, or other types of IQ modulators; its sine wave generator can be a radio frequency source, an arbitrary waveform generator (AWG), a waveform generator based on a field programmable gate array (FPGA), or a waveform generator based on an application-specific integrated circuit (ASIC). Circuit, ASIC) waveform generator, the frequency and amplitude of which are adjustable; the mode converter can be one or more of an optical fiber mode selective coupler made by fused taper method, an optical fiber mode selective coupler made by side polishing method, a mode selective coupler based on silicate glass substrate made by 3D laser direct writing method, a planar optical waveguide mode selective coupler, a long period fiber grating mode converter, a mechanical phase plate mode converter, a mode converter based on spatial light modulator, a multi-plane light converter and a photon lantern; the mode controller can be a mechanical mode controller, a manual mode controller, a A type controller or any other device that can change the ratio of the eigenmode combination of the degenerate mode; the 90:10 optical power splitter can be an optical fiber coupler made by a fused taper method, an optical fiber coupler made by a side polishing method, a coupler based on a silicate glass substrate made by a 3D laser direct writing method, a planar optical waveguide coupler, or a power splitter based on a spatial light modulator; the optical detector can be an optical detector based on a PIN photodiode or an optical detector based on an avalanche photodiode; the signal collector can be a real-time oscilloscope, a real-time electrical signal collector based on a field programmable gate array (FPGA), or a real-time electrical signal collector based on an application specific integrated circuit (ASIC); the computing unit can obtain a digital signal of the measured optical signal and calculate the differential mode delay within the degenerate mode and the differential mode delay coefficient within the degenerate mode based on the digital signal.

[0168] The method for measuring intra-degenerate mode differential mode delay using the above-mentioned intra-degenerate mode differential mode delay measurement device in few-mode optical fiber based on single-sideband sinusoidal modulation may specifically include the following steps:

[0169] 1) Select a measured few-mode fiber with a length of L (corresponding to the above-mentioned few-mode fiber to be measured), place it between the mode converter and the mode controller of the above-mentioned degenerate mode intra-differential mode delay measurement device based on single-sideband sinusoidal modulation in the few-mode fiber, place the mode converter corresponding to the measured mode in the degenerate mode intra-differential mode delay measurement device based on single-sideband sinusoidal modulation in the few-mode fiber, and adjust the optical path. The optical power loss from the IQ modulator to the 90:10 optical power splitter is IL. Specifically, the optical power loss can be measured in advance using a power meter. The measurement process is as follows: first measure the optical power entering the IQ modulator, then measure the optical power exiting the 90 port of the 90:10 optical power splitter, and subtract the two values ​​to obtain the optical power loss.

[0170] 2) adjusting the output working wavelength and output power of the light source to a preset working wavelength and preset output power P0 (corresponding to the output power of the light source), setting the frequency of the sine wave to f1 (corresponding to the frequency of the sine wave generated by the sine wave generator), and adjusting the IQ modulator so that the laser emitted by the light source is modulated into a single-sideband optical signal;

[0171] 3) adjusting the mode controller to determine, through the mode component discriminator, whether the ratio of the eigenmode components of the specific degenerate mode under test (corresponding to the degenerate mode to be tested) is equal, so that the ratio of the eigenmode components of the specific degenerate mode under test is maintained in an equal state, and the signal collector collects the measured optical power signal P;

[0172] 4) Obtain the intra-degenerate mode differential mode delay and the intra-degenerate mode differential mode delay coefficient of the measured degenerate mode in the measured few-mode fiber at the preset working wavelength calculated by the calculation unit, and the intra-degenerate mode differential mode delay Δτ of the measured degenerate mode in the measured few-mode fiber at the working wavelength λ IDM-DMD The calculation formula (corresponding to the above formula 1) is:

[0173]

[0174] Where arccos is the inverse cosine function. The differential mode delay coefficient C in the measured degenerate mode in the measured few-mode fiber IDM-DMD The calculation formula (corresponding to the above formula 3) is:

[0175]

[0176] In the method for measuring differential mode delay within a degenerate mode in a few-mode optical fiber based on single-sideband sinusoidal modulation, the length L of the few-mode optical fiber to be measured can be between 0 and 100 km.

[0177] The following is a specific example of Scheme 1.

[0178] The differential mode delay measurement device in the degenerate mode of the few-mode optical fiber based on single-sideband sinusoidal modulation of the present invention can be specifically as follows: Figure 4 As shown, it includes a light source, an IQ modulator, a mode converter, a mode controller, a 90:10 optical power splitter, and a photodetector arranged in sequence along the optical path, as well as a mode component discriminator optically connected to the 90:10 optical power splitter, a sine wave generator electrically connected to the IQ modulator, a signal collector electrically connected to the photodetector, and a computing unit digitally connected to the signal collector. Among them:

[0179] The working wavelength of the light source is adjustable, such as Figure 4 As shown, it includes a narrow-linewidth continuous laser light source and a polarization-maintaining single-mode optical fiber (the polarization-maintaining single-mode optical fiber will be directly connected to the IQ modulator as a line, which belongs to the internal structure of the light source. The light source includes a narrow-linewidth continuous laser light source and a polarization-maintaining single-mode optical fiber, which can be understood as a narrow-linewidth continuous laser light source with polarization-maintaining output); the narrow-linewidth continuous laser light source is used to provide linearly polarized narrow-linewidth continuous laser, and the operating wavelength range can be between 400-1700nm, the continuously adjustable laser linewidth is less than 5MHz, and the laser power is continuously adjustable between 0-1W; the polarization-maintaining single-mode optical fiber transmits the linearly polarized light output by the narrow-linewidth continuous laser light source and forms a fundamental mode, and its output end is used to output light to the IQ modulator, and the output end can be optionally provided with a connector; the polarization-maintaining single-mode optical fiber is a bare optical fiber or a jumper.

[0180] The sine wave generator is used to generate a sine wave radio frequency signal, and can be optionally an adjustable radio frequency source. Its output end is used to output an electrical signal to the IQ modulator, and can be optionally an radio frequency connector.

[0181] The IQ modulator is used to modulate the sinusoidal radio frequency signal generated by the sine wave generator onto the linearly polarized laser emitted by the light source to form a modulated single-sideband optical signal, and can be optionally a lithium niobate modulator; its optical input end is used for light input and can be optionally connected to the light source; its optical output end is used to output light to the mode converter, and the optical input and output ends can optionally be provided with connectors; its electrical input end is used for electrical signal input and can be optionally connected to the sine wave generator.

[0182] The mode converter is used to convert the fundamental mode in the single-mode optical fiber into a specific degenerate mode in the few-mode optical fiber to be tested, and optionally both its input and output ends have optical fiber connectors based on jumpers.

[0183] The mode controller is used to control the change of the intrinsic mode combination ratio of the degenerate mode, and optionally both its input and output ends have optical fiber connectors based on jumpers.

[0184] The 90:10 optical power splitter is used to split the optical signal into two paths with a power ratio of 90:10. It can be an optical fiber coupler made by the fused taper method, and its input and output ends both have optical fiber connectors based on jumpers.

[0185] The mode component discriminator is used to identify the intrinsic mode combination ratio of the optical signal and can notify the mode controller and the signal collector of the identification result. Optionally, both the optical input and output ends of the discriminator have optical fiber connectors based on jumpers.

[0186] The optical detector is used to convert optical signals into electrical signals. Its optical input end has an optical fiber connector based on a jumper, and its electrical output end is optionally connected to a time domain electrical signal acquisition unit. The optional electrical output end is a radio frequency connector.

[0187] The signal collector is used to collect electrical signals into digital signals, and can be a real-time oscilloscope.

[0188] The calculation unit is used to obtain the digital signal collected by the signal collector and calculate the degenerate mode intra-differential mode delay and its coefficient of the measured degenerate mode in the measured few-mode optical fiber.

[0189] The method for measuring differential mode delay within a degenerate mode in a few-mode optical fiber based on single-sideband sinusoidal modulation using the above device may specifically include the following steps:

[0190] 1) Selecting a measured few-mode fiber with a length of L (corresponding to the above-mentioned few-mode fiber to be tested), placing it between the mode converter and the mode controller of the above-mentioned degenerate mode intra-differential mode delay measurement device based on single-sideband sinusoidal modulation in the few-mode fiber, placing the mode converter corresponding to the measured mode in the degenerate mode intra-differential mode delay measurement device based on single-sideband sinusoidal modulation in the few-mode fiber, and adjusting the optical path. The optical power loss from the IQ modulator to the 90:10 optical power splitter is IL;

[0191] The tested few-mode fiber takes the annular six-mode fiber as an example: supports LP 01 LP 11 LP 21 LP 02 LP 31 LP 12 There are six degenerate modes, among which LP 01 and LP 02 The mode is a circularly symmetric degenerate mode, LP 11 LP 21 LP 31 LP 12 It is a non-circularly symmetric degenerate mode; the length L of the measured optical fiber is 100 km, and its input and output ends are provided with connectors.

[0192] 2) adjusting the output operating wavelength λ of the light source to 1550 nm, the output power to 13 dBm, setting the frequency f1 of the sine wave to 10 GHz, and adjusting the IQ modulator so that the laser emitted by the light source is modulated into a single-sideband optical signal;

[0193] 3) adjusting the mode controller to determine whether the ratio of the eigenmode components of the measured specific degenerate mode is equal through the mode component discriminator, so that the ratio of the eigenmode components of the measured specific degenerate mode is maintained in an equal state, and the signal collector collects the measured optical power signal P;

[0194] 4) Obtain the intra-degenerate mode differential mode delay and the intra-degenerate mode differential mode delay coefficient of the measured degenerate mode in the measured few-mode fiber at the preset working wavelength calculated by the calculation unit, and the intra-degenerate mode differential mode delay Δτ of the measured degenerate mode in the measured few-mode fiber at the working wavelength λ IDM-DMD The calculation formula is:

[0195]

[0196] Where arccos is the inverse cosine function. The differential mode delay coefficient C in the measured degenerate mode in the measured few-mode fiber IDM-DMD The calculation formula is:

[0197]

[0198] In the method for measuring differential mode delay within a degenerate mode in a few-mode optical fiber based on single-sideband sinusoidal modulation, the length L of the few-mode optical fiber to be measured can be between 0 and 100 km.

[0199] The test results are shown in Table 1. 01 The differential mode delay in the circularly symmetric degenerate mode after the mode is transmitted through 100km of circular six-mode fiber is 1.2ps, and the differential mode delay coefficient in the circularly symmetric degenerate mode is 0.12ps / km. 1 / 2 LP 11 The differential mode delay in the non-circularly symmetric degenerate mode after the mode is transmitted through a 100km circular six-mode optical fiber is 32.3ps, and the differential mode delay coefficient in the non-circularly symmetric degenerate mode is 3.23ps / km. 1 / 2 LP 21 The differential mode delay in the circularly symmetric degenerate mode after the mode is transmitted through 100 km of circular six-mode fiber is 37.4 ps, and the differential mode delay coefficient in the non-circularly symmetric degenerate mode is 3.74 ps / km. 1 / 2 LP 02 The differential mode delay in the circularly symmetric degenerate mode after the mode is transmitted through 100km of circular six-mode fiber is 1.4ps, and the differential mode delay coefficient in the circularly symmetric degenerate mode is 0.14ps / km. 1 / 2 LP31 The differential mode delay in the non-circularly symmetric degenerate mode after the mode is transmitted through a 100km circular six-mode optical fiber is 41.4ps, and the differential mode delay coefficient in the non-circularly symmetric degenerate mode is 4.14ps / km. 1 / 2 LP 12 The differential mode delay in the non-circularly symmetric degenerate mode after the mode is transmitted through a 100km ring six-mode fiber is 55.3ps, and the differential mode delay coefficient in the non-circularly symmetric degenerate mode is 5.53ps / km. 1 / 2 .

[0200] Table 1 Measured differential mode delay and coefficients within the degenerate mode

[0201]

[0202] Part 2, the solution 2 adopted by the present invention to solve the above-mentioned problem is:

[0203] (1) A device for measuring differential mode delay in a degenerate mode of a few-mode optical fiber based on single-sideband linear frequency modulation is provided, comprising a light source, an IQ modulator, a linear frequency modulation wave generator (a specific implementation example of a signal generator), a mode converter, a mode controller, a light detector, a frequency domain electrical signal collector (a specific implementation example of a signal collector), and a computing unit;

[0204] (2) Provided is a method for measuring differential mode delay within a degenerate mode in a few-mode optical fiber based on single-sideband linear frequency modulation, which applies the above-mentioned differential mode delay measurement device within a degenerate mode in a few-mode optical fiber based on single-sideband linear frequency modulation.

[0205] like Figure 5As shown, the device for measuring differential mode delay in a degenerate mode of a few-mode optical fiber based on single-sideband linear frequency modulation: the light source, IQ modulator, mode converter, mode controller and optical detector are arranged in sequence on the optical path; the linear frequency modulation wave generator is electrically connected to the IQ modulator; the frequency domain electrical signal collector is electrically connected to the optical detector; the calculation unit is connected to the digital signal of the frequency domain electrical signal collector; the light source is used to generate a linearly polarized laser; the linear frequency modulation wave generator is used to generate a linear frequency modulation electrical signal; the IQ modulator is used to modulate the linear frequency modulation electrical signal generated by the linear frequency modulation wave generator to the linear polarization emitted by the light source A modulated single-sideband optical signal is formed on the laser; the mode converter is used to convert the fundamental mode in the single-mode optical fiber into a specific degenerate mode (corresponding to the above-mentioned degenerate mode to be measured) in the measured few-mode optical fiber; the mode controller is used to control the ratio of the eigenmode combination that changes the degenerate mode; the optical detector is used to convert the optical signal into an electrical signal; the frequency domain electrical signal collector is used to collect the frequency domain electrical signal and convert it into a digital signal (i.e., collect the electrical signal into a digital signal); the computing unit is used to obtain the digital signal collected by the frequency domain electrical signal collector and calculate the degenerate mode intra-differential mode delay and its coefficient of the measured degenerate mode in the measured few-mode optical fiber.

[0206] Optionally, the device for measuring differential mode delay in a degenerate mode of a few-mode optical fiber based on single-sideband linear frequency modulation has an adjustable light source operating wavelength, spectrum width, and laser power, and is used to provide narrow-spectrum continuous laser light. The light source operating wavelength range is continuously adjustable between 400-1700nm, the laser linewidth is less than 5MHz, and the laser power is continuously adjustable between 0-1W; its IQ modulator can be a lithium niobate modulator, a silicon-based modulator, an indium phosphide modulator, or other types of IQ modulators; its linear frequency modulation wave generator can be a radio frequency source, an arbitrary waveform generator (AWG), a waveform generator based on a field programmable gate array (FPGA), or a waveform generator based on an application-specific integrated circuit (ASIC). Circuit (ASIC), whose sweep range (i.e., the sweep frequency range (not amplitude)) and sweep rate are adjustable; its mode converter can be one or more of an optical fiber mode selective coupler made by a fused taper method, an optical fiber mode selective coupler made by a side polishing method, a mode selective coupler based on a silicate glass substrate made by a 3D laser direct writing method, a planar optical waveguide mode selective coupler, a long period fiber grating mode converter, a mechanical phase plate mode converter, a mode converter based on a spatial light modulator, a multi-plane optical converter, and a photon lantern; its mode controller can be a mechanical mode controller, a manual mode controller, or any other device that can change the ratio of the eigenmode combination of the degenerate mode; the optical detector can be an optical detector based on a PIN photodiode or an optical detector based on an avalanche photodiode; the frequency domain electrical signal collector can be a real-time electrical frequency domain electrical signal collector, a real-time frequency domain electrical signal collector based on a field programmable gate array (FPGA), or a real-time frequency domain electrical signal collector based on an application specific integrated circuit (ASIC). The real-time frequency domain electrical signal collector of the optical signal processor (ASIC) is a device that uses an integrated circuit (IC) to acquire digital signals of the measured optical signal and, based on these signals, calculate the intra-degenerate mode differential mode delay and the intra-degenerate mode differential mode delay coefficient. Regarding the frequency sweep rate, assuming the frequency sweep starts at frequency f3 and ends at frequency f4, and the time taken to move from f3 to f4 is t, the frequency sweep rate is (f4-f3) / t.

[0207] The method for measuring the intra-degenerate mode differential mode delay using the above-mentioned intra-degenerate mode differential mode delay measurement device in a few-mode optical fiber based on single-sideband linear frequency modulation may specifically include the following steps:

[0208] 1) selecting a measured few-mode fiber with a length of L (corresponding to the few-mode fiber to be measured) and placing it between a mode converter and a mode controller of the above-mentioned apparatus for measuring differential mode delay within a degenerate mode in a few-mode fiber based on single-sideband linear frequency modulation, placing a mode converter corresponding to the measured mode in the apparatus for measuring differential mode delay within a degenerate mode in a few-mode fiber based on single-sideband linear frequency modulation, and adjusting the optical path;

[0209] 2) adjusting the output operating wavelength and output power of the light source to a preset operating wavelength and preset output power, configuring the sweep range and sweep speed (i.e., sweep rate) of the linear frequency modulation wave generating unit to a preset sweep range and sweep speed γ (corresponding to the sweep speed of the linear frequency modulation wave generator), and adjusting the IQ modulator so that the laser emitted by the light source unit is modulated into a single-sideband linear frequency modulation optical signal;

[0210] 3) adjusting the mode controller and observing the frequency domain information displayed by the frequency domain electrical signal collector so that the frequency domain peak reaches a maximum value, and recording the frequency f2 of the frequency domain peak (corresponding to the frequency corresponding to the above peak value);

[0211] 4) Obtain the intra-degenerate mode differential mode delay and the intra-degenerate mode differential mode delay coefficient of the measured degenerate mode in the measured few-mode fiber at the preset working wavelength calculated by the calculation unit, and the intra-degenerate mode differential mode delay Δτ of the measured degenerate mode in the measured few-mode fiber at the working wavelength IDM-DMD The calculation formula (corresponding to the above formula 2) is:

[0212]

[0213] The differential mode delay coefficient C of the measured degenerate mode in the measured few-mode fiber IDM-DMD The calculation formula (corresponding to the above formula 3) is:

[0214]

[0215] In the method for measuring differential mode delay within a degenerate mode in a few-mode optical fiber based on single-sideband linear frequency modulation, the length L of the few-mode optical fiber to be measured can be between 0 and 100 km.

[0216] For reference, the sine wave generator above the IQ modulator in Solution 1 is used, while a linear frequency modulation (LFM) generator is used in Solution 2. The waveforms used to measure the generated signals differ. Solution 1 uses a sine wave generator, belonging to the time domain measurement solution, while Solution 2 uses a LFM generator, belonging to the frequency domain measurement solution. Solution 2 also does not require mode cost identification, resulting in a simpler structure.

[0217] The following is a specific example of solution 2.

[0218] The differential mode delay measurement device in the degenerate mode of the few-mode optical fiber based on single-sideband linear frequency modulation of the present invention can be specifically as follows: Figure 6 As shown, it includes a light source, an IQ modulator, a mode converter, a mode controller and a light detector arranged in sequence along the optical path, as well as a linear frequency modulation wave generator electrically connected to the IQ modulator, a frequency domain electrical signal collector electrically connected to the light detector, and a computing unit digitally connected to the frequency domain electrical signal collector.

[0219] The working wavelength of the light source is adjustable, such as Figure 6 As shown, it includes a narrow-linewidth continuous laser light source and a polarization-maintaining single-mode optical fiber (the polarization-maintaining single-mode optical fiber will be directly connected to the IQ modulator as a line, which belongs to the internal structure of the light source. The light source includes a narrow-linewidth continuous laser light source and a polarization-maintaining single-mode optical fiber, which can be understood as a narrow-linewidth continuous laser light source with polarization-maintaining output); the narrow-linewidth continuous laser light source is used to provide linearly polarized narrow-linewidth continuous laser, and the operating wavelength range can be between 400-1700nm, the continuously adjustable laser linewidth is less than 5MHz, and the laser power is continuously adjustable between 0-1W; the polarization-maintaining single-mode optical fiber transmits the linearly polarized light output by the narrow-linewidth continuous laser light source and forms a fundamental mode, and its output end is used to output light to the IQ modulator, and the output end can be optionally provided with a connector; the polarization-maintaining single-mode optical fiber is a bare optical fiber or a jumper.

[0220] The linear frequency modulation wave generator is used to generate a linear frequency modulation wave signal, and can be optionally an adjustable radio frequency source. Its output end is used to output an electrical signal to the IQ modulator, and can be optionally an radio frequency connector.

[0221] The IQ modulator is used to modulate the linear frequency modulation wave signal generated by the linear frequency modulation wave generator onto the linearly polarized laser emitted by the light source to form a modulated single-sideband optical signal, and can be optionally a lithium niobate modulator; its optical input end is used for light input and can be optionally connected to the light source; its optical output end is used to output light to the mode converter, and the optical input and output ends can optionally be provided with connectors, and its electrical input end is used for electrical signal input and can be optionally connected to the linear frequency modulation wave generator.

[0222] The mode converter is used to convert the fundamental mode in the single-mode optical fiber into a specific degenerate mode in the few-mode optical fiber to be tested, and optionally both its input and output ends have optical fiber connectors based on jumpers.

[0223] The mode controller is used to control the change of the intrinsic mode combination ratio of the degenerate mode, and optionally both its input and output ends have optical fiber connectors based on jumpers.

[0224] The optical detector is used to convert optical signals into electrical signals. Its optical input end has an optical fiber connector based on a jumper, and its electrical output end is optionally connected to a frequency domain electrical signal acquisition unit. The optional electrical output end is a radio frequency connector.

[0225] The frequency domain electrical signal collector is used to collect frequency domain electrical signals and convert them into digital signals, and can optionally be a real-time electrical spectrum analyzer.

[0226] The calculation unit is used to obtain the digital signal of the frequency domain electrical signal collector and calculate the degenerate mode intra-differential mode delay and its coefficient of the measured degenerate mode in the measured few-mode optical fiber.

[0227] The method for measuring differential mode delay in a degenerate mode of a few-mode fiber based on single-sideband linear frequency modulation using the above device may specifically include the following steps:

[0228] 1) selecting a measured few-mode fiber with a length of L (corresponding to the few-mode fiber to be measured) and placing it between a mode converter and a mode controller of the above-mentioned apparatus for measuring differential mode delay within a degenerate mode in a few-mode fiber based on single-sideband linear frequency modulation, placing a mode converter corresponding to the measured mode in the apparatus for measuring differential mode delay within a degenerate mode in a few-mode fiber based on single-sideband linear frequency modulation, and adjusting the optical path;

[0229] The tested few-mode fiber takes the annular six-mode fiber as an example: supports LP 01 LP 11 LP 21 LP 02 LP 31 LP 12 There are six degenerate modes, among which LP 01 and LP 02 The mode is a circularly symmetric degenerate mode, LP 11 LP 21 LP 31 LP 12 It is a non-circularly symmetric degenerate mode; the length L of the measured optical fiber is 100 km, and its input and output ends are provided with connectors.

[0230] 2) adjusting the output operating wavelength λ of the light source to 1550 nm and the output power to 13 dBm, configuring the sweep frequency range of the linear frequency modulation wave generating unit to 0-1 GHz and the sweep frequency speed γ to 1014 Hz / s, and adjusting the IQ modulator so that the laser emitted by the light source unit is modulated into a single-sideband linear frequency modulation optical signal;

[0231] 3) adjusting the mode controller and observing the frequency domain information displayed by the frequency domain electrical signal collector so that the frequency domain peak reaches a maximum value, and recording the frequency f2 of the frequency domain peak;

[0232] 4) Obtain the intra-degenerate mode differential mode delay and the intra-degenerate mode differential mode delay coefficient of the measured degenerate mode in the measured few-mode fiber at the preset working wavelength calculated by the calculation unit, and the intra-degenerate mode differential mode delay Δτ of the measured degenerate mode in the measured few-mode fiber at the working wavelength λIDM-DMD The calculation formula is:

[0233]

[0234] The differential mode delay coefficient C of the measured degenerate mode in the measured few-mode fiber IDM-DMD The calculation formula is:

[0235]

[0236] In the method for measuring differential mode delay within a degenerate mode in a few-mode optical fiber based on single-sideband linear frequency modulation, the length L of the few-mode optical fiber to be measured can be between 0 and 100 km.

[0237] The test results are shown in Table 2. 01 The differential mode delay in the circularly symmetric degenerate mode after the mode is transmitted through 100km of circular six-mode fiber is 1.2ps, and the differential mode delay coefficient in the circularly symmetric degenerate mode is 0.12ps / km. 1 / 2 LP 11 The differential mode delay in the non-circularly symmetric degenerate mode after the mode is transmitted through a 100km circular six-mode optical fiber is 32.3ps, and the differential mode delay coefficient in the non-circularly symmetric degenerate mode is 3.23ps / km. 1 / 2 LP 21 The differential mode delay in the circularly symmetric degenerate mode after the mode is transmitted through 100 km of circular six-mode fiber is 37.4 ps, and the differential mode delay coefficient in the non-circularly symmetric degenerate mode is 3.74 ps / km. 1 / 2 LP 02 The differential mode delay in the circularly symmetric degenerate mode after the mode is transmitted through 100km of circular six-mode fiber is 1.4ps, and the differential mode delay coefficient in the circularly symmetric degenerate mode is 0.14ps / km. 1 / 2 LP 31 The differential mode delay in the non-circularly symmetric degenerate mode after the mode is transmitted through a 100km circular six-mode optical fiber is 41.4ps, and the differential mode delay coefficient in the non-circularly symmetric degenerate mode is 4.14ps / km. 1 / 2 LP 12 The differential mode delay in the non-circularly symmetric degenerate mode after the mode is transmitted through a 100km ring six-mode optical fiber is 55.3ps, and the differential mode delay coefficient in the non-circularly symmetric degenerate mode is 5.53ps / km. 1 / 2 .

[0238] Table 2 Measured differential mode delay and coefficients within the degenerate mode

[0239]

[0240]

[0241] As can be seen from the above, the solution provided by the embodiment of the present invention mainly involves: generating a time domain signal through a sine wave generator, or generating a frequency domain signal through a linear frequency modulation wave generator, then accurately measuring the output signal, and then analyzing the values ​​of various parameters. Specifically, it involves:

[0242] Solution 1, a device for measuring differential mode delay within a degenerate mode in a few-mode optical fiber based on single-sideband sinusoidal modulation, which includes a light source, an IQ modulator, a sine wave generator, a mode converter, a mode controller, a 90:10 optical power splitter, a light detector, a signal collector and a calculation unit.

[0243] Among them, the time domain signal is generated by a sine wave generator, and the signal is collected through a 90:10 optical power splitter, a mode controller, a light detector, etc.

[0244] Solution 2, a device for measuring differential mode delay within a degenerate mode in a few-mode optical fiber based on single-sideband linear frequency modulation, which includes a light source, an IQ modulator, a linear frequency modulation wave generator, a mode converter, a mode controller, a light detector, a frequency domain electrical signal collector and a computing unit.

[0245] Among them, the frequency domain signal is generated by a linear frequency modulation wave generator, and the signal is collected and analyzed by a light detector.

[0246] The difference between Solution 1 and Solution 2 is that one generates a time-domain signal, while the other generates a frequency-domain signal. The similarities are that both generate, measure, and analyze signals, and then derive the differential mode delay within the degenerate mode of the fiber under test.

[0247] In summary, the beneficial effects of this solution are:

[0248] 1) This solution provides a device and method for measuring the differential mode delay within the degenerate mode in two few-mode optical fibers. By selecting and designing the structure and components, the device and method achieve detection of the degenerate mode. The device is simple, reliable, and highly integrated, and can conveniently and accurately measure the differential mode delay within the degenerate mode. This allows for separating the differential mode delay within the degenerate mode from chromatic dispersion and accurately measuring the differential mode delay within the degenerate mode.

[0249] 2) The two devices for measuring differential mode delay within a degenerate mode in a few-mode optical fiber and the method for measuring differential mode delay within a degenerate mode in a few-mode optical fiber based on the devices provided in this solution have the advantages of fast measurement speed and accurate measurement.

[0250] 3) The two methods for measuring the differential mode delay within the degenerate mode of the few-mode fiber provided in this solution can reduce the number of times the few-mode fiber is disassembled and assembled. The debugging is simple, and the differential mode delay and coefficient within the measured degenerate mode can be obtained in one debugging, which greatly reduces the workload and has a high degree of automation.

[0251] It is explained here that the few-mode fiber mentioned above refers to an optical fiber that supports multiple waveguide modes; the degenerate mode refers to a mode composed of eigenvector modes with similar effective refractive indices; the differential mode delay within the degenerate mode refers to the delay accumulated during the transmission process due to the slight difference in effective refractive index and propagation speed between the eigenvector modes within the same degenerate mode.

[0252] The embodiment of the present invention further provides a delay measurement device, which is applied to the above-mentioned delay measurement device, such as Figure 7 As shown, the device includes:

[0253] The first modulation module 71 is used to modulate the signal generated by the signal generator onto the linearly polarized laser emitted by the light source using an IQ modulator to form a modulated single-sideband optical signal;

[0254] a conversion and transmission module 72 for converting the fundamental mode in the few-mode optical fiber to be tested into a degenerate mode to be tested using a mode converter, and sending the single-sideband optical signal to the few-mode optical fiber to be tested;

[0255] The transmission adjustment module 73 is used to adjust the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested by using the mode controller, obtain the adjusted optical signal, and transmit it to the optical detector;

[0256] a conversion and transmission module 74 for converting part or all of the adjusted optical signal into a digital signal using the optical detector and the signal collector, and transmitting the digital signal to the computing unit;

[0257] The first processing module 75 is configured to obtain, by using the calculation unit and according to the digital signal, the intra-degenerate mode differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested.

[0258] The delay measurement device provided by the embodiment of the present invention uses an IQ modulator to modulate the signal generated by the signal generator onto the linearly polarized laser emitted by the light source to form a modulated single-sideband optical signal; uses a mode converter to convert the fundamental mode in the few-mode optical fiber to be measured into a degenerate mode to be measured, and sends the single-sideband optical signal to the few-mode optical fiber to be measured; uses a mode controller to adjust the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be measured to obtain an adjusted optical signal, and transmits it to a light detector; uses the light detector and a signal collector to convert part or all of the adjusted optical signal into a digital signal, and transmits it to a computing unit; uses the computing unit to obtain a digital signal. According to the digital signal, the degenerate mode intra-differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested is obtained; the degenerate mode intra-differential mode delay and chromatic dispersion can be separated, and the degenerate mode intra-differential mode delay information can be quickly and accurately measured, thereby achieving simple, fast and accurate measurement of the degenerate mode intra-differential mode delay information; in addition, the present solution can reduce the number of times the few-mode optical fiber is disassembled and assembled, and the debugging is simple. The degenerate mode intra-differential mode delay information to be tested can be obtained in one debugging, which greatly reduces the workload and has a high degree of automation; and the present solution effectively solves the problem in the prior art of being unable to accurately measure the degenerate mode intra-differential mode delay.

[0259] The intra-degenerate mode differential mode delay information includes at least one of a degenerate mode intra-differential mode delay value and a degenerate mode intra-differential mode delay coefficient.

[0260] In an embodiment of the present invention, the signal generator may be a sine wave generator; the mode controller is used to adjust the eigenmode combination ratio of the optical signal output by the few-mode optical fiber to be tested, the adjusted optical signal is obtained, and the optical signal is transmitted to the optical detector, including: using the mode controller to adjust the eigenmode combination ratio of the optical signal output by the few-mode optical fiber to be tested, the adjusted optical signal is obtained, and the optical signal is transmitted to the optical power splitter; using the optical power splitter to divide the adjusted optical signal, and sending the optical signal with larger power to the optical detector, and sending the optical signal with smaller power to the mode component discriminator; using the mode component discriminator to determine whether the eigenmode combination ratio is in an equal state, and when the eigenmode combination ratio is not in an equal state When the eigenmode combination ratio is in an equal state, the identification result is sent to the mode controller, and the method returns to execute the method of adjusting the eigenmode combination ratio of the optical signal output by the tested few-mode optical fiber by using the mode controller until the eigenmode combination ratio is in an equal state; when the eigenmode combination ratio is in an equal state, the identification result is sent to the mode controller and the signal collector; the method of converting part of the adjusted optical signal into a digital signal by using the optical detector and the signal collector includes: converting the optical signal with higher power into an electrical signal by using the optical detector, and sending it to the signal collector; and collecting the time domain electrical signal corresponding to the electrical signal transmitted by the optical detector according to the identification result by using the signal collector, and converting it into a digital signal.

[0261] The digital signal includes an optical power signal value P; and using the calculation unit to obtain, according to the digital signal, the differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested, includes: using the calculation unit to obtain, according to the optical power signal value P, the differential mode delay value of the few-mode optical fiber to be tested in the degenerate mode to be tested in the degenerate mode to be tested using Formula 1; wherein Formula 1 is: The Δτ IDM-DMD represents the differential mode delay value in the degenerate mode; π represents the pi ratio; f1 represents the frequency of the sine wave generated by the sine wave generator; P0 represents the output power of the light source; IL represents the optical power loss from the IQ modulator to the optical power splitter.

[0262] In an embodiment of the present invention, the signal generator may be a linear frequency modulation wave generator; the use of the optical detector and the signal collector to convert all the adjusted optical signals into digital signals includes: using the optical detector to convert all the adjusted optical signals into electrical signals, and sending them to the signal collector; using the signal collector to collect the frequency domain electrical signal corresponding to the electrical signal transmitted by the optical detector, and converting it into a digital signal; using the mode controller to adjust the eigenmode combination ratio of the optical signal output by the few-mode optical fiber to be tested, obtain the adjusted optical signal, and transmit it to the optical detector, including: executing at least once the use of the mode controller to adjust the eigenmode combination ratio of the optical signal output by the few-mode optical fiber to be tested, obtain the adjusted optical signal, and transmit it to the optical detector; until the frequency domain electrical signal reaches a peak value.

[0263] The digital signal includes a frequency f2 corresponding to the peak; and using the calculation unit to obtain, according to the digital signal, the differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested, includes: using the calculation unit to obtain, according to the frequency f2, the differential mode delay value of the few-mode optical fiber to be tested in the degenerate mode to be tested in the degenerate mode to be tested using Formula 2; wherein Formula 2 is: The Δτ IDM-DMD represents the differential mode delay value in the degenerate mode; and γ represents the sweep speed of the linear frequency modulation wave generator.

[0264] Furthermore, the method of using the calculation unit to obtain, according to the digital signal, the degenerate mode differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested further includes: using the calculation unit to obtain, according to the degenerate mode differential mode delay value, the degenerate mode differential mode delay coefficient of the few-mode optical fiber to be tested in the degenerate mode to be tested using Formula 3; wherein Formula 3 is: The C IDM-DMD represents the differential mode delay coefficient in the degenerate mode; the Δτ IDM-DMD represents the differential mode delay value in the degenerate mode; and L represents the length of the few-mode optical fiber to be tested.

[0265] Among them, the implementation embodiments of the above-mentioned delay measurement method are all applicable to the embodiments of the delay measurement device and can also achieve the same technical effects.

[0266] The embodiment of the present invention further provides a delay measurement device, including the components included in the above-mentioned delay measurement device, such as Figure 8 As shown, the delay measurement device further includes: a processor 81 and a transceiver 82;

[0267] The processor 81 is configured to modulate the signal generated by the signal generator onto the linearly polarized laser light emitted by the light source using an IQ modulator to form a modulated single-sideband optical signal;

[0268] Using a mode converter to convert the fundamental mode in the few-mode optical fiber to be tested into a degenerate mode to be tested, and sending the single-sideband optical signal to the few-mode optical fiber to be tested;

[0269] Using a mode controller to adjust the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested, obtain an adjusted optical signal, and transmit it to a light detector;

[0270] Using the light detector and the signal collector, convert part or all of the adjusted light signal into a digital signal and transmit it to the computing unit;

[0271] The calculation unit is used to obtain, according to the digital signal, the intra-degenerate mode differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested.

[0272] The delay measurement device provided by the embodiment of the present invention uses an IQ modulator to modulate the signal generated by the signal generator onto the linearly polarized laser emitted by the light source to form a modulated single-sideband optical signal; uses a mode converter to convert the fundamental mode in the few-mode optical fiber to be measured into a degenerate mode to be measured, and sends the single-sideband optical signal to the few-mode optical fiber to be measured; uses a mode controller to adjust the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be measured, obtains the adjusted optical signal, and transmits it to the optical detector; uses the optical detector and the signal collector to convert part or all of the adjusted optical signal into a digital signal, and transmits it to the computing unit; uses the computing unit to obtain the adjusted optical signal. According to the digital signal, the degenerate mode intra-differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested is obtained; the degenerate mode intra-differential mode delay and chromatic dispersion can be separated, and the degenerate mode intra-differential mode delay information can be quickly and accurately measured, thereby achieving simple, fast and accurate measurement of the degenerate mode intra-differential mode delay information; in addition, the present solution can reduce the number of times the few-mode optical fiber is disassembled and assembled, and the debugging is simple. The degenerate mode intra-differential mode delay information to be tested can be obtained in one debugging, which greatly reduces the workload and has a high degree of automation; and the present solution effectively solves the problem in the prior art of being unable to accurately measure the degenerate mode intra-differential mode delay.

[0273] The intra-degenerate mode differential mode delay information includes at least one of a degenerate mode intra-differential mode delay value and a degenerate mode intra-differential mode delay coefficient.

[0274] In an embodiment of the present invention, the signal generator may be a sine wave generator; the mode controller is used to adjust the eigenmode combination ratio of the optical signal output by the few-mode optical fiber to be tested, the adjusted optical signal is obtained, and the optical signal is transmitted to the optical detector, including: using the mode controller to adjust the eigenmode combination ratio of the optical signal output by the few-mode optical fiber to be tested, the adjusted optical signal is obtained, and the optical signal is transmitted to the optical power splitter; using the optical power splitter to divide the adjusted optical signal, and sending the optical signal with larger power to the optical detector, and sending the optical signal with smaller power to the mode component discriminator; using the mode component discriminator to determine whether the eigenmode combination ratio is in an equal state, and when the eigenmode combination ratio is not in an equal state When the eigenmode combination ratio is in an equal state, the identification result is sent to the mode controller, and the method returns to execute the method of adjusting the eigenmode combination ratio of the optical signal output by the tested few-mode optical fiber by using the mode controller until the eigenmode combination ratio is in an equal state; when the eigenmode combination ratio is in an equal state, the identification result is sent to the mode controller and the signal collector; the method of converting part of the adjusted optical signal into a digital signal by using the optical detector and the signal collector includes: converting the optical signal with higher power into an electrical signal by using the optical detector, and sending it to the signal collector; and collecting the time domain electrical signal corresponding to the electrical signal transmitted by the optical detector according to the identification result by using the signal collector, and converting it into a digital signal.

[0275] The digital signal includes an optical power signal value P; and using the calculation unit to obtain, according to the digital signal, the differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested, includes: using the calculation unit to obtain, according to the optical power signal value P, the differential mode delay value of the few-mode optical fiber to be tested in the degenerate mode to be tested in the degenerate mode to be tested using Formula 1; wherein Formula 1 is: The Δτ IDM-DMD represents the differential mode delay value in the degenerate mode; π represents the pi ratio; f1 represents the frequency of the sine wave generated by the sine wave generator; P0 represents the output power of the light source; IL represents the optical power loss from the IQ modulator to the optical power splitter.

[0276] In an embodiment of the present invention, the signal generator may be a linear frequency modulation wave generator; the use of the optical detector and the signal collector to convert all the adjusted optical signals into digital signals includes: using the optical detector to convert all the adjusted optical signals into electrical signals, and sending them to the signal collector; using the signal collector to collect the frequency domain electrical signal corresponding to the electrical signal transmitted by the optical detector, and converting it into a digital signal; using the mode controller to adjust the eigenmode combination ratio of the optical signal output by the few-mode optical fiber to be tested, obtain the adjusted optical signal, and transmit it to the optical detector, including: executing at least once the use of the mode controller to adjust the eigenmode combination ratio of the optical signal output by the few-mode optical fiber to be tested, obtain the adjusted optical signal, and transmit it to the optical detector; until the frequency domain electrical signal reaches a peak value.

[0277] The digital signal includes a frequency f2 corresponding to the peak; and using the calculation unit to obtain, according to the digital signal, the differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested, includes: using the calculation unit to obtain, according to the frequency f2, the differential mode delay value of the few-mode optical fiber to be tested in the degenerate mode to be tested in the degenerate mode to be tested using Formula 2; wherein Formula 2 is: The Δτ IDM-DMD represents the differential mode delay value in the degenerate mode; and γ represents the sweep speed of the linear frequency modulation wave generator.

[0278] Furthermore, the method of using the calculation unit to obtain, according to the digital signal, the degenerate mode differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested further includes: using the calculation unit to obtain, according to the degenerate mode differential mode delay value, the degenerate mode differential mode delay coefficient of the few-mode optical fiber to be tested in the degenerate mode to be tested using Formula 3; wherein Formula 3 is: The C IDM-DMD represents the differential mode delay coefficient in the degenerate mode; the Δτ IDM-DMD represents the differential mode delay value in the degenerate mode; and L represents the length of the few-mode optical fiber to be tested.

[0279] Among them, the implementation embodiments of the above-mentioned delay measurement method are all applicable to the embodiments of the delay measurement device and can achieve the same technical effects.

[0280] An embodiment of the present invention further provides a delay measurement device, comprising a memory, a processor, and a program stored in the memory and executable on the processor; the processor implements the above-mentioned delay measurement method when executing the program.

[0281] Among them, the implementation embodiments of the above-mentioned delay measurement method are all applicable to the embodiments of the delay measurement device and can achieve the same technical effects.

[0282] An embodiment of the present invention further provides a readable storage medium storing a program, which implements the steps in the above-mentioned delay measurement method when executed by a processor.

[0283] Among them, the implementation embodiments of the above-mentioned delay measurement method are all applicable to the embodiments of the readable storage medium and can achieve the same technical effects.

[0284] It should be noted that many functional components described in this specification are referred to as modules in order to more particularly emphasize the independence of their implementation methods.

[0285] In embodiments of the present invention, modules can be implemented in software so that they can be executed by various types of processors. For example, an identified executable code module can include one or more physical or logical blocks of computer instructions, for example, which can be constructed as objects, procedures, or functions. Nevertheless, the executable code of the identified module does not need to be physically located together, but can include different instructions stored in different locations, which, when logically combined together, constitute the module and achieve the specified purpose of the module.

[0286] 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 in the middle of 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.Described 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.

[0287] When a module can be implemented using software, given the current state of hardware technology, those skilled in the art can build corresponding hardware circuits to implement the corresponding functions of the module, regardless of cost. The hardware circuits may include conventional very large scale integration (VLSI) circuits or gate arrays, as well as existing semiconductors such as logic chips and transistors, or other discrete components. Modules may also be implemented using programmable hardware devices, such as field programmable gate arrays, programmable array logic, or programmable logic devices.

[0288] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary personnel 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 time delay measurement device, characterized in that: include: A light source, an IQ modulator and a mode converter connected in sequence; and, a mode controller capable of being connected to the output end of the few-mode optical fiber to be tested; and, a signal measurement sub-device; The signal measurement sub-device includes: a light detector connected to the mode controller, and a calculation unit connected to the light detector via a signal collector; The mode converter can be connected to the input end of the few-mode optical fiber to be tested; the IQ modulator is also connected to a signal generator; the IQ modulator modulates the signal generated by the signal generator onto the linearly polarized laser emitted by the light source to form a modulated single-sideband optical signal; The calculation unit is capable of determining the differential mode delay information within the degenerate mode of the few-mode optical fiber to be tested according to the signal collected by the signal collector; Wherein, the signal generator is a sine wave generator, and the device further comprises: an optical power splitter provided between the mode controller and the optical detector, and a mode component discriminator connected to the mode controller, the optical power splitter and the signal collector respectively; The calculation unit is capable of determining the intra-degenerate mode differential mode delay information of the few-mode optical fiber to be tested according to the signal collected by the signal collector, including: The calculation unit obtains the degenerate mode differential mode delay value of the few-mode optical fiber to be tested in the degenerate mode to be tested using Formula 1 according to the optical power signal value P output by the signal collector; Wherein, the formula 1 is: The optical power signal value P is obtained based on the signal collected by the signal collector; The △τ IDM-DMD represents the differential mode delay value in the degenerate mode; π represents the ratio of pi; f1 represents the frequency of the sine wave generated by the sine wave generator; P0 represents the output power of the light source; IL represents the optical power loss from the IQ modulator to the optical power splitter; Alternatively, the signal generator is a linear frequency modulation wave generator, and the signal collector is a frequency domain electrical signal collector; The calculation unit is capable of determining the intra-degenerate mode differential mode delay information of the few-mode optical fiber to be tested according to the signal collected by the signal collector, including: The calculation unit obtains the intra-degenerate mode differential mode delay value of the few-mode optical fiber to be tested in the degenerate mode to be tested using Formula 2 according to the frequency f2 corresponding to the peak value of the frequency domain electrical signal output by the signal collector; Wherein, the formula 2 is: The frequency f2 is obtained based on the signal collected by the signal collector; The △τ IDM-DMD represents the differential mode delay value in the degenerate mode; and γ represents the sweep speed of the linear frequency modulation wave generator.

2. A delay measurement method, applied to the delay measurement device according to claim 1, characterized in that: The method comprises: The signal generated by the signal generator is modulated by an IQ modulator onto the linearly polarized laser emitted by the light source to form a modulated single-sideband optical signal; Using a mode converter to convert the fundamental mode in the few-mode optical fiber to be tested into a degenerate mode to be tested, and sending the single-sideband optical signal to the few-mode optical fiber to be tested; Using a mode controller to adjust the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested, obtain an adjusted optical signal, and transmit it to a light detector; Using the light detector and the signal collector, convert part or all of the adjusted light signal into a digital signal and transmit it to the computing unit; The calculation unit is used to obtain, according to the digital signal, the intra-degenerate mode differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested.

3. The delay measurement method according to claim 2, wherein: The intra-degenerate mode differential mode delay information includes at least one of a degenerate mode intra-differential mode delay value and a degenerate mode intra-differential mode delay coefficient.

4. The delay measurement method according to claim 2, wherein: The signal generator is a sine wave generator; The method of adjusting the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested by using the mode controller to obtain the adjusted optical signal and transmitting the adjusted optical signal to the optical detector includes: Using a mode controller to adjust the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested, obtain an adjusted optical signal, and transmit it to an optical power splitter; Using the optical power splitter to divide the adjusted optical signal, and sending the optical signal with higher power to the optical detector, and sending the optical signal with lower power to the mode component discriminator; Determining whether the eigenmode combination ratio is in an equal state using the mode component identifier, and if the eigenmode combination ratio is not in an equal state, sending the identification result to the mode controller, returning to execute the step of adjusting the eigenmode combination ratio of the optical signal output by the few-mode optical fiber to be tested using the mode controller until the eigenmode combination ratio is in an equal state; and sending the identification result to the mode controller and the signal collector if the eigenmode combination ratio is in an equal state; The method of converting part of the adjusted optical signal into a digital signal by using the optical detector and the signal collector includes: Using the light detector to convert the high-power optical signal into an electrical signal and send it to a signal collector; The signal collector is used to collect the time domain electrical signal corresponding to the electrical signal transmitted by the light detector according to the identification result, and convert it into a digital signal.

5. The delay measurement method according to claim 4, characterized in that: The digital signal includes an optical power signal value P; The obtaining, using the calculation unit, according to the digital signal, the differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested includes: Using the calculation unit, according to the optical power signal value P, using formula 1, obtain the degenerate mode differential mode delay value of the few-mode optical fiber to be tested in the degenerate mode to be tested; Wherein, the formula 1 is: The △τ IDM-DMD represents the differential mode delay value in the degenerate mode; π represents the pi ratio; f1 represents the frequency of the sine wave generated by the sine wave generator; P0 represents the output power of the light source; IL represents the optical power loss from the IQ modulator to the optical power splitter.

6. The delay measurement method according to claim 2, wherein: The signal generator is a linear frequency modulation wave generator; The method of converting all the adjusted optical signals into digital signals by using the optical detector and the signal collector includes: Using the light detector to convert all the adjusted optical signals into electrical signals and send them to a signal collector; Using the signal collector to collect the frequency domain electrical signal corresponding to the electrical signal transmitted by the light detector, and converting it into a digital signal; The method of adjusting the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested by using the mode controller to obtain the adjusted optical signal and transmitting the adjusted optical signal to the optical detector includes: The method of adjusting the eigenmode combination ratio of the optical signal output by the few-mode optical fiber to be tested by using the mode controller is performed at least once to obtain an adjusted optical signal, and transmit the adjusted optical signal to the optical detector; until the frequency domain electrical signal reaches a peak value.

7. The delay measurement method according to claim 6, characterized in that: The digital signal includes a frequency f2 corresponding to the peak value; The obtaining, using the calculation unit, according to the digital signal, the differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested includes: Using the calculation unit, according to the frequency f2, and using Formula 2, obtain the degenerate mode differential mode delay value of the few-mode optical fiber to be tested in the degenerate mode to be tested; Wherein, the formula 2 is: The △τ IDM-DMD represents the differential mode delay value in the degenerate mode; and γ represents the sweep speed of the linear frequency modulation wave generator.

8. The delay measurement method according to claim 5 or 7, characterized in that: The step of obtaining, by the calculation unit, the differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested according to the digital signal further includes: Using the calculation unit, according to the intra-degenerate mode differential mode delay value, using Formula 3, obtain the intra-degenerate mode differential mode delay coefficient of the few-mode optical fiber to be tested in the degenerate mode to be tested; Wherein, the formula three is: The C IDM-DMD represents the differential mode delay coefficient in the degenerate mode; the △τ IDM-DMD represents the differential mode delay value in the degenerate mode; and L represents the length of the few-mode optical fiber to be tested.

9. A delay measurement device, applied to the delay measurement equipment according to claim 1, characterized in that: The device comprises: The first modulation module is used to modulate the signal generated by the signal generator onto the linearly polarized laser emitted by the light source using an IQ modulator to form a modulated single-sideband optical signal; a conversion and transmission module, configured to convert the fundamental mode in the few-mode optical fiber to be tested into a degenerate mode to be tested using a mode converter, and to send the single-sideband optical signal to the few-mode optical fiber to be tested; an adjusting transmission module, configured to adjust the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested by using a mode controller, obtain an adjusted optical signal, and transmit the adjusted optical signal to a light detector; a conversion and transmission module, configured to convert part or all of the adjusted optical signal into a digital signal using the optical detector and the signal collector, and transmit the digital signal to the computing unit; The first processing module is configured to obtain, by using the calculation unit and according to the digital signal, the intra-degenerate mode differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested.

10. The delay measurement device according to claim 9, characterized in that: The intra-degenerate mode differential mode delay information includes at least one of a degenerate mode intra-differential mode delay value and a degenerate mode intra-differential mode delay coefficient.

11. The delay measurement device according to claim 9, characterized in that: The signal generator is a sine wave generator; The method of adjusting the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested by using the mode controller to obtain the adjusted optical signal and transmitting the adjusted optical signal to the optical detector includes: Using a mode controller to adjust the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested, obtain an adjusted optical signal, and transmit it to an optical power splitter; Using the optical power splitter to divide the adjusted optical signal, and sending the optical signal with higher power to the optical detector, and sending the optical signal with lower power to the mode component discriminator; Determining whether the eigenmode combination ratio is in an equal state using the mode component identifier, and if the eigenmode combination ratio is not in an equal state, sending the identification result to the mode controller, returning to execute the step of adjusting the eigenmode combination ratio of the optical signal output by the few-mode optical fiber to be tested using the mode controller until the eigenmode combination ratio is in an equal state; and sending the identification result to the mode controller and the signal collector if the eigenmode combination ratio is in an equal state; The method of converting part of the adjusted optical signal into a digital signal by using the optical detector and the signal collector includes: Using the light detector to convert the high-power optical signal into an electrical signal and send it to a signal collector; The signal collector is used to collect the time domain electrical signal corresponding to the electrical signal transmitted by the light detector according to the identification result, and convert it into a digital signal.

12. The delay measurement device according to claim 11, characterized in that: The digital signal includes an optical power signal value P; The obtaining, using the calculation unit, according to the digital signal, the differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested includes: Using the calculation unit, according to the optical power signal value P, using formula 1, obtain the degenerate mode differential mode delay value of the few-mode optical fiber to be tested in the degenerate mode to be tested; Wherein, the formula 1 is: The △τ IDM-DMD represents the differential mode delay value in the degenerate mode; π represents the pi ratio; f1 represents the frequency of the sine wave generated by the sine wave generator; P0 represents the output power of the light source; IL represents the optical power loss from the IQ modulator to the optical power splitter.

13. The delay measurement device according to claim 9, characterized in that: The signal generator is a linear frequency modulation wave generator; The method of converting all the adjusted optical signals into digital signals by using the optical detector and the signal collector includes: Using the light detector to convert all the adjusted optical signals into electrical signals and send them to a signal collector; Using the signal collector to collect the frequency domain electrical signal corresponding to the electrical signal transmitted by the light detector, and converting it into a digital signal; The method of adjusting the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested by using the mode controller to obtain the adjusted optical signal and transmitting the adjusted optical signal to the optical detector includes: The method of adjusting the eigenmode combination ratio of the optical signal output by the few-mode optical fiber to be tested by using the mode controller is performed at least once to obtain an adjusted optical signal, and transmit the adjusted optical signal to the optical detector; until the frequency domain electrical signal reaches a peak value.

14. The delay measurement device according to claim 13, characterized in that: The digital signal includes a frequency f2 corresponding to the peak value; The obtaining, using the calculation unit, according to the digital signal, the differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested includes: Using the calculation unit, according to the frequency f2, and using Formula 2, obtain the degenerate mode differential mode delay value of the few-mode optical fiber to be tested in the degenerate mode to be tested; Wherein, the formula 2 is: The △τ IDM-DMD represents the differential mode delay value in the degenerate mode; and γ represents the sweep speed of the linear frequency modulation wave generator.

15. The delay measurement device according to claim 12 or 14, characterized in that: The step of obtaining, by the calculation unit, the differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested according to the digital signal further includes: Using the calculation unit, according to the intra-degenerate mode differential mode delay value, using Formula 3, obtain the intra-degenerate mode differential mode delay coefficient of the few-mode optical fiber to be tested in the degenerate mode to be tested; Wherein, the formula three is: The C IDM-DMD represents the differential mode delay coefficient in the degenerate mode; the △τ IDM-DMD represents the differential mode delay value in the degenerate mode; and L represents the length of the few-mode optical fiber to be tested.

16. A delay measurement device, comprising the components of the delay measurement device according to claim 1, characterized in that: The delay measurement device further includes: a processor and a transceiver; The processor is used to modulate the signal generated by the signal generator onto the linearly polarized laser emitted by the light source using an IQ modulator to form a modulated single-sideband optical signal; Using a mode converter to convert the fundamental mode in the few-mode optical fiber to be tested into a degenerate mode to be tested, and sending the single-sideband optical signal to the few-mode optical fiber to be tested; Using a mode controller to adjust the intrinsic mode combination ratio of the optical signal output by the few-mode optical fiber to be tested, obtain an adjusted optical signal, and transmit it to a light detector; Using the light detector and the signal collector, convert part or all of the adjusted light signal into a digital signal and transmit it to the computing unit; The calculation unit is used to obtain, according to the digital signal, the intra-degenerate mode differential mode delay information of the few-mode optical fiber to be tested in the degenerate mode to be tested.

17. A delay measurement device comprising a memory, a processor, and a program stored in the memory and executable on the processor; characterized in that: When the processor executes the program, the delay measurement method according to any one of claims 2 to 8 is implemented.

18. A readable storage medium having a program stored thereon, characterized in that: When the program is executed by a processor, the steps of the delay measurement method according to any one of claims 2 to 8 are implemented.

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