WO2022237271A1 - 一种光纤测量系统 - Google Patents

一种光纤测量系统 Download PDF

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Publication number
WO2022237271A1
WO2022237271A1 PCT/CN2022/077509 CN2022077509W WO2022237271A1 WO 2022237271 A1 WO2022237271 A1 WO 2022237271A1 CN 2022077509 W CN2022077509 W CN 2022077509W WO 2022237271 A1 WO2022237271 A1 WO 2022237271A1
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Prior art keywords
light
wavelength
optical
measurement
fiber
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PCT/CN2022/077509
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English (en)
French (fr)
Inventor
郭强
周锐
杨志群
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华为技术有限公司
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Priority to EP22806248.5A priority Critical patent/EP4325741A1/en
Publication of WO2022237271A1 publication Critical patent/WO2022237271A1/zh
Priority to US18/506,628 priority patent/US20240077382A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/05—Spatial multiplexing systems
    • H04J14/052—Spatial multiplexing systems using multicore fibre
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
    • H04B10/071—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using a reflected signal, e.g. using optical time domain reflectometers [OTDR]
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G01M11/30—Testing of optical devices, constituted by fibre optics or optical waveguides
    • G01M11/31—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter and a light receiver being disposed at the same side of a fibre or waveguide end-face, e.g. reflectometers
    • G01M11/3109—Reflectometers detecting the back-scattered light in the time-domain, e.g. OTDR
    • G01M11/3127—Reflectometers detecting the back-scattered light in the time-domain, e.g. OTDR using multiple or wavelength variable input source
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G01M11/30—Testing of optical devices, constituted by fibre optics or optical waveguides
    • G01M11/31—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter and a light receiver being disposed at the same side of a fibre or waveguide end-face, e.g. reflectometers
    • G01M11/319—Reflectometers using stimulated back-scatter, e.g. Raman or fibre amplifiers

Definitions

  • the present application relates to the technical field of optical communication, in particular to an optical fiber measurement system.
  • the conventional method of measuring optical fiber is: sending measurement light from one end of the optical fiber into the optical fiber, collecting the backward return light generated when the measurement light propagates in the optical fiber, and using the backward return light to obtain the signal attenuation information in the optical fiber .
  • the stimulated Raman scattering effect will occur, and the specific performance is that the power of the short-wavelength light will be transferred to the power of the long-wavelength light. Therefore, no matter the wavelength of the measurement light is longer than the wavelength of the signal light Or short, this measurement method will cause the transmission of measurement light to be affected by signal light due to power transfer, resulting in inaccurate backward return light collected finally, which is not conducive to improving the accuracy of measurement results.
  • the present application provides an optical fiber measurement system, which is used to improve the accuracy of optical fiber measurement.
  • the application provides an optical fiber measurement system, including a signal generator, a first optical time domain reflectometer and a wavelength division multiplexer, the signal generator is used to send signal light to the wavelength division multiplexer, and the first optical time domain reflectometer is used In order to send the first measurement light and the second measurement light whose wavelengths are respectively located on both sides of the wavelength of the signal light to the wavelength division multiplexer, the wavelength division multiplexer is used to combine the first measurement light, the second measurement light and the signal light After processing, it is sent to the optical fiber, and the returned light in the optical fiber is sent to the first optical time domain reflectometer, and the first optical time domain reflectometer is also used to determine the performance of the optical fiber according to the returned light.
  • the power of the short-wavelength measuring light can be transferred to the side of the signal light, and the power of the signal light can be transferred to the long-wavelength measuring light. Therefore, using the return light of the two measurement lights to comprehensively determine the performance of the optical fiber can make the power transfer of the two measurement lights in the measurement results cancel each other without affecting the normal service transmission of the signal light, effectively eliminating The interference of various stimulated scattering effects on the measurement process improves the accuracy of the measurement results.
  • the first optical time domain reflectometer can also send different first measurement light and second measurement light to the optical fiber multiple times, and determine the optical fiber in each measurement according to the light returned by each measurement.
  • the performance in the optical fiber is integrated with the performance of the optical fiber in multiple measurements to determine the true performance of the optical fiber, for example, the average value of the performance obtained from multiple measurements is taken as the true performance of the optical fiber.
  • the signal light may be single-wavelength signal light or multi-wavelength signal light.
  • the wavelengths of the first measurement light and the second measurement light are respectively located on both sides of the wavelength of the signal light, which may mean that the wavelength of the first measurement light is greater than the wavelength of the single-wavelength signal light, The wavelength of the second measurement light is smaller than the wavelength of the single-wavelength signal light.
  • the wavelengths of the first measurement light and the second measurement light are located on both sides of the wavelength of the signal light, which may mean that the wavelength of the first measurement light is greater than the maximum wavelength of the multi-wavelength signal light , the wavelength of the second measurement light is smaller than the minimum wavelength of the multi-wavelength signal light.
  • the wavelength of one measurement light to be greater than the wavelength of the signal light (that is, a single wavelength or the maximum wavelength), and the wavelength of the other measurement light to be smaller than the wavelength of the signal light (that is, a single wavelength or the minimum wavelength)
  • the wavelength of the other measurement light to be smaller than the wavelength of the signal light (that is, a single wavelength or the minimum wavelength)
  • the wavelength difference between the wavelength of the first measurement light and the maximum wavelength, and the wavelength difference between the minimum wavelength and the wavelength of the second measurement light can all be within a preset Raman gain range, wherein the preset The Raman gain range is the maximum wavelength difference that causes two optical signals of different wavelengths to have an obvious stimulated Raman scattering effect.
  • the design can ensure that both the first measurement light and the second measurement light undergo power transfer with the signal light, effectively improving the possibility of canceling the power transfer in the measurement result.
  • the first optical time domain reflectometer may include a wave splitter and a processor, and the wave splitter is used to split the returned light into first returned light and second measured light corresponding to the first measurement light corresponding to the second returned light, and send the first returned light and the second returned light to the processor, and the processor is used to determine the performance of the optical fiber according to the first returned light and the second returned light.
  • This design can accurately separate the return light corresponding to the first measurement light and the second measurement light through the wave splitter, which helps the processor determine the performance of each measurement light according to the return light corresponding to each measurement light, so as to synthesize Determine the overall performance of the fiber.
  • the wavelength difference between the wavelength of the first measuring light and the central wavelength of the signal light is the same as the wavelength difference between the central wavelength of the signal light and the wavelength of the second measuring light.
  • the power transferred out of the short-wavelength measurement light is equal to the power transferred into the long-wavelength measurement light. In this way, the direct sum of the two The performance curve corresponding to one measurement light can offset the power transfer amount of two measurement lights with a high probability.
  • This calculation method is relatively simple, easy to implement, and helps to improve measurement efficiency.
  • the performance curve may specifically be a power decay curve. Since the propagation velocity of light is fixed, after the first optical time domain reflectometer emits the measurement light, the power of the returned light received at different times also represents the power of the loss at different positions in the optical fiber, through statistics The loss power at each position of the optical fiber can obtain the power attenuation curve to accurately characterize the transmission attenuation performance of the optical fiber at each position.
  • the processor is specifically configured to: obtain the first performance curve of the optical fiber according to the first returned light, obtain the second performance curve of the optical fiber according to the second returned light, and weight the first performance curve and the second performance curve , to obtain the target performance curve of the fiber.
  • the first optical time-domain reflectometer can determine the performance of the optical fiber in a weighted way, compared to the input at both ends.
  • the weighting calculation method is simpler, easy to implement, and helps to improve measurement efficiency.
  • the ratio of the weight corresponding to the first performance curve to the weight corresponding to the second performance curve and the frequency difference between the frequency of the signal light and the frequency of the first measurement light and the frequency difference between the frequency of the second measurement light and the signal light The ratio of the frequency difference of the frequency is positively correlated.
  • the frequency of the signal light may correspond to the frequency of the single-wavelength signal light or the center frequency of the multi-wavelength signal light.
  • the design refers to the positive linear correspondence between the relative frequency of the two optical signals and the transfer of power consumption.
  • the corresponding weight By setting the corresponding weight according to the frequency difference between the measurement light and the signal light, it can refer to the first measurement light Set the weight of the first performance curve and the weight of the second performance curve equally with the real power transfer situation of the second measurement light, and try to make the weighted two performance curves correspond to one positive and one negative power transfer with the same value.
  • This kind of weight setting is more reasonable and accurate, which can better correct the influence of power transfer on the two returned lights collected, and further improve the accuracy of the measurement results.
  • the signal generator may include K signal generating units, and the K signal generating units correspond to the K wave bands one by one, and each signal generating unit in the K signal generating units is used for WDM The user sends the signal light in the corresponding wavelength band, and K is a positive integer greater than or equal to 2.
  • the K wavebands may include but not limited to: O-band (wavelength range 1260nm-1360nm), E-band (wavelength range 1360nm-1460nm), S-band (wavelength range 1460nm-1530nm), C-band (wavelength range 1530nm-1565nm), L-band (wavelength range 1565nm-1625nm), etc.
  • this design can be applied to the measurement of optical fibers that mix and transmit multi-band signals. Since the scattering effect of optical fibers will become more obvious when mixing and transmitting multi-band signals, it is necessary to use a method that can counteract power transfer in optical fibers that mix and transmit multi-band signals. The measurement can effectively improve the accuracy of the measurement results.
  • the optical fiber measurement system may also include a wave division multiplexer and a second optical time domain reflectometer connected to the wave division multiplexer, wherein the wavelength division multiplexer and the wave division multiplexer are respectively located at both ends of the fiber.
  • the second optical time domain reflectometer is used to send the third measurement light and the fourth measurement light whose wavelengths are respectively located on both sides of the wavelength of the signal light to the wave division multiplexer, and the wave division multiplexer is used to combine the third measurement light
  • the light and the fourth measurement light are sent to the fiber, and the light returned from the fiber is sent to a second optical time domain reflectometer, which is also used to determine the performance of the fiber in the other direction from the returned light.
  • the fiber can also be measured from two directions, by obtaining the loss information of each position in the fiber in two directions , which helps to accurately locate the problem point of the fiber.
  • the wavelengths of the first measuring light, the second measuring light, the third measuring light and the fourth measuring light are different from each other.
  • the measurement light sent from the opposite side will not affect the returned light received by the optical time domain reflectometer on this side, and the measurement in two directions will be reduced.
  • the mutual interference can effectively improve the measurement accuracy in each direction.
  • the optical fiber measured by the first optical time domain reflectometer can have multiple situations, for example:
  • the optical fiber can be directly connected to the signal generator, and the first optical time domain reflectometer uses the signal light emitted by the signal generator and the two wavelengths on both sides of the signal light A measurement light, to achieve accurate measurement of the first section of optical fiber.
  • the optical fiber measurement system can also include an optical fiber amplifier, and the input end of the optical fiber amplifier is connected to the output end of the last section of optical fiber (the input end of the last section of optical fiber can be directly connected to the signal Generator, or connected to the signal generator through other optical fibers), the output end of the optical fiber amplifier is connected to the wavelength division multiplexer, and the optical fiber amplifier is used to amplify the power of the signal light transmitted from the previous section of optical fiber and then send it to the wavelength division multiplexer.
  • the optical fiber amplifier to amplify the power of the weaker signal light transmitted through the multi-segment optical fiber, the optical power loss caused by the transmission through the multi-segment optical fiber can be compensated, and the long-distance transmission of the signal can be realized.
  • the optical fiber amplifier can include at least two amplifiers, the input end of the wave division multiplexer is connected to the output end of a section of optical fiber, and at least two output ends of the wave division multiplexer are respectively connected to at least two amplifiers The input terminals of at least two amplifiers are respectively connected to the wavelength division multiplexer.
  • the wave division multiplexer is used to demultiplex the signal light transmitted from the previous section of optical fiber into optical signals in at least two wavebands, and send the optical signals in at least two wavebands to at least two amplifiers respectively, At least two amplifiers amplify the power of the received optical signal in the wavelength band and send it to the wavelength division multiplexer. This design can amplify the signal light of each band in a more targeted manner, and helps to set the amplification factor of the amplifier according to the actual needs of each band.
  • the optical fiber can be a multi-core optical fiber
  • the number of the first optical time domain reflectometer and the wavelength division multiplexer can be multiple
  • the multiple wavelength division multiplexers and the multiple The fiber cores are in one-to-one correspondence
  • the multiple wavelength division multiplexers are in one-to-one correspondence with the multiple first optical time domain reflectometers.
  • the optical fiber measurement system may also include a first fan-in and fan-out device for connecting multiple wavelength division multiplexers and multi-core optical fibers, and the first fan-in and fan-out device can respectively combine the wavelength division multiplexers
  • the processed light is sent to the fiber core corresponding to the wavelength division multiplexer, and the light returned by multiple fiber cores is sent to the wavelength division multiplexer corresponding to each of the multiple fiber cores, and then received via the wavelength division multiplexer
  • the light returned by the fiber core is sent to the corresponding first optical time domain reflector, and the performance of the corresponding fiber core among the plurality of fiber cores is determined by the first optical time domain reflectometer according to the light returned by the fiber core.
  • the design enables unidirectional measurements in one direction of the performance of each core in a multicore fiber.
  • the unidirectional measurement process of multiple fiber cores can be carried out together, that is, multiple first optical time domain reflectometers emit measurement light at the same time, and the first fan-in and fan-out device simultaneously combines the multiplexed light Coupled to multiple fiber cores respectively; it is also possible to measure only one fiber core at a time, that is, only one first optical time-domain reflectometer emits measurement light at a time, and a combined light is coupled by the first fan-in and fan-out device to one fiber core; it can also be completed in multiple measurements, and a part of the fiber cores are measured each time, which is not specifically limited.
  • the optical fiber measurement system can also include a wave division multiplexer and a second optical time domain reflectometer, and the number of the wave division multiplexer and the second optical time domain reflectometer can be multiple.
  • a wave division multiplexer is in one-to-one correspondence with a plurality of fiber cores in the multi-core optical fiber
  • a plurality of second optical time domain reflectometers is in one-to-one correspondence with a plurality of wave division multiplexers
  • the optical fiber measurement system may also include a A second fan-in-fan-out device that connects multiple WDMs and multi-core fibers.
  • the second optical time domain reflectometer can send two measurement lights whose wavelengths are on both sides of the wavelength of the signal light to the connected wave division multiplexer, and the connected second optical time domain reflector can be connected by the wave division multiplexer.
  • the two measurement lights sent by the domain reflectometer are sent to the second fan-in and fan-out device, and then the second fan-in and fan-out device respectively couples the two measurement lights sent by the wave division multiplexer to the corresponding wavelength division multiplexer core, and the light returned by the multiple cores is sent to the wave division multiplexer corresponding to each of the multiple cores, and the received light returned by the core is sent to the corresponding second light by the wave division multiplexer
  • a domain reflectometer, and then a second optical time domain reflectometer determines the performance of a corresponding fiber core in the plurality of fiber cores in another direction according to the light returned by the fiber core. This design enables measurement of the performance of each core in a multi-core fiber from the other direction.
  • the two-way measurement process of multiple fiber cores can be carried out together, that is, multiple first optical time domain reflectometers and multiple second optical time domain reflectometers emit measurement light at the same time, and the first fan-in and fan-out device At the same time, the measurement light emitted by multiple first optical time domain reflectometers is forward-coupled to multiple fiber cores, and the measurement light emitted by multiple second optical time domain reflectometers is simultaneously reverse-coupled to multiple fiber cores by the second fan-in and fan-out device.
  • the fiber core to realize simultaneous bidirectional measurement of multiple fiber cores; it is also possible to measure only one fiber core bidirectionally at a time, that is, only the first optical time domain reflectometer and the second optical time domain reflector corresponding to the fiber core to be tested are
  • the reflectometer emits measurement light
  • the first fan-in and fan-out device forward-couples the measurement light emitted by the first optical time domain reflectometer to the fiber core to be tested
  • the second fan-in and fan-out device couples the second optical time domain reflectometer
  • the emitted measuring light is reversely coupled to the fiber core to be tested; the measurement can also be completed in multiple times, and a part of the fiber core is bidirectionally measured each time, which is not specifically limited.
  • the optical fiber can be a few-mode fiber
  • the number of the first optical time domain reflectometer and the wavelength division multiplexer can be multiple
  • the multiple wavelength division multiplexers and the multiple The modes correspond one-to-one
  • the multiple wavelength division multiplexers correspond to the multiple first optical time domain reflectometers one-to-one.
  • the optical fiber measurement system may also include a first mode multiplexer for connecting multiple wavelength division multiplexers and few-mode fibers, and the first mode multiplexer can combine multiple wavelength division multiplexers for processing After the light is converted into different modes, it is sent to the least-mode fiber, and the light of different modes returned by the few-mode fiber is de-mode-processed, and then sent to the respective corresponding wavelength division multiplexers, and then multiple wavelength division multiplexers Returning to the corresponding first optical time-domain reflectometers, each first optical time-domain reflectometer determines the performance of the corresponding mode in the few-mode fiber according to the returned light after mode removal. The design enables unidirectional measurements in one direction of the performance of each mode in a few-mode fiber.
  • a plurality of wavelength division multiplexers can respectively send combined light in their respective fundamental modes to the mode multiplexer, and the first mode multiplexer can convert the multiplexed light sent by each wavelength division multiplexer It is a high-order mode, and each high-order mode converted by each wavelength division multiplexer is weakly coupled (weak coupling means that the mutual influence is relatively weak, which can be ignored, or can be eliminated by an optical time domain reflectometer).
  • the first mode multiplexer can perform demode processing on the light in each high-order mode to obtain the respective fundamental modes of each wavelength division multiplexer The returned light is sent to each wavelength division multiplexer. In this way, each wavelength division multiplexer can determine the performance of the fundamental mode, that is, the converted high-order mode corresponding to the fundamental mode, according to the received return light in the corresponding fundamental mode.
  • the one-way measurement process of multiple modes can be carried out together, that is, multiple first optical time domain reflectometers emit measurement light at the same time, and the first mode multiplexer simultaneously converts the multiplexed light to obtain
  • the corresponding various modes are coupled into the optical fiber; it is also possible to measure only one mode at a time, that is, only one first optical time domain reflectometer emits measurement light at a time, and only one mode is converted by the first mode multiplexer after multiplex processing
  • the light obtained in one mode is coupled into the optical fiber; the measurement can also be done in multiple times, and part of the modes are measured each time, which is not specifically limited.
  • the optical fiber measurement system can also include a wave division multiplexer and a second optical time domain reflectometer, and the number of the wave division multiplexer and the second optical time domain reflectometer can be multiple.
  • the wave division multiplexer is in one-to-one correspondence with the multiple modes in the few-mode optical fiber
  • the multiple second optical time domain reflectometers are in one-to-one correspondence with the multiple wave division multiplexers.
  • the optical fiber measurement system can also include multiple A wave division multiplexer and a second mode multiplexer for few-mode fiber.
  • the second optical time domain reflectometer can send two measurement lights whose wavelengths are on both sides of the wavelength of the signal light to the connected wave division multiplexer, and the connected second optical time domain reflector can be connected by the wave division multiplexer.
  • the two measurement lights sent by the domain reflectometer are sent to the second mode multiplexer
  • the two measurement lights sent by multiple wave division multiplexers are converted into different modes by the second mode multiplexer, and then sent to the at least mode optical fiber
  • the light of different modes returned by the few-mode fiber is de-mode-processed, and then sent to the respective corresponding wave division multiplexers, and then the wave-division multiplexer de-mode-processes the returned light corresponding to the received mode It is sent to the corresponding second optical time-domain reflectometer, and the second optical time-domain reflectometer determines the performance of the corresponding mode in the few-mode fiber in the other direction according to the returned light after de-mode processing.
  • This design enables measurement of the performance of each mode in a few-mode fiber from the
  • the two-way measurement process of multiple modes can be carried out together, that is, multiple first optical time domain reflectometers and multiple second optical time domain reflectometers emit measurement light at the same time, and the first mode multiplexer generates multiple Each corresponding mode of the measurement light emitted by a first optical time domain reflectometer is forward-coupled to at least one mode fiber at the same time, and the respective modes corresponding to the measurement light emitted by a plurality of second optical time domain reflectometers are generated by the second mode multiplexer Afterwards, at least the mode core is reversely coupled at the same time to realize the simultaneous bidirectional measurement of multiple modes in the few-mode fiber; it can also be that only one mode is bidirectionally measured at a time, that is, only the first light corresponding to the mode to be measured is The measurement light is emitted by the domain reflectometer and the second optical time domain reflectometer, and the measurement light emitted by the first optical time domain reflectometer is converted into the mode to be measured by the first mode multiplexer and then forwardly coupled to the
  • the returned light may include Rayleigh scattered light or Brillouin scattered light when the measurement light is transmitted in the optical fiber.
  • the first optical time domain reflectometer can also change the type of scattering by controlling the power intensity of the output measurement light, for example, by setting the power of the measurement light to be less than 7dBm, so that Rayleigh scattering does not occur in the optical fiber and Brillouin scattering occurs, by setting The power of the measuring light is greater than 7dBm, so that Rayleigh scattering and Brillouin scattering occur simultaneously in the optical fiber.
  • the intensity of the measuring light to change the type of scattering in the fiber, the performance of the fiber under different types of scattering can be measured according to actual needs, and the applicable range of fiber measurement can be improved.
  • FIG. 1 exemplarily shows a schematic structural diagram of an optical communication system to which an embodiment of the present application is applicable;
  • FIG. 2 exemplarily shows a schematic structural diagram of an optical fiber measurement system provided by an embodiment of the present application
  • FIG. 3 exemplarily shows a corresponding relationship between power transfer and relative frequency provided by the embodiment of the present application
  • FIG. 4 exemplarily shows a schematic diagram of a unidirectional power attenuation curve of an optical fiber provided in an embodiment of the present application
  • FIG. 5 exemplarily shows a schematic structural diagram of a system for measuring C+L wavelength division multiplexing provided by an embodiment of the present application
  • FIG. 6 exemplarily shows a schematic diagram of a bidirectional power attenuation curve of an optical fiber provided by an embodiment of the present application
  • FIG. 7 exemplarily shows a schematic structural diagram of a measurement core division multiplexing system provided by an embodiment of the present application.
  • FIG. 8 exemplarily shows a schematic structural diagram of another measurement core division multiplexing system provided by an embodiment of the present application.
  • FIG. 9 exemplarily shows a schematic diagram of the architecture of a measurement mode division multiplexing system provided by an embodiment of the present application.
  • FIG. 10 exemplarily shows a schematic structural diagram of a measurement mode division multiplexing system provided by an embodiment of the present application.
  • FIG. 11 exemplarily shows a schematic diagram of signal flow in a different mode provided by the embodiment of the present application.
  • optical fiber measurement scheme in the embodiment of the present application can be applied to an optical communication system.
  • An optical communication system uses light as a carrier and uses a very fine optical fiber drawn from high-purity glass as a transmission medium. Through photoelectric conversion, a communication system that uses light to transmit information is realized.
  • Common optical communication systems include but are not limited to: when divided by wavelength, they can include short-wavelength optical communication systems (working wavelengths in the range of 0.8 ⁇ m-0.9 ⁇ m), long-wavelength optical communication systems (working wavelengths in the range of 1.0 ⁇ m-1.6 ⁇ m range), and ultra-long optical communication systems (operating wavelength greater than 1.6 ⁇ m); when divided according to the mode of optical fiber, it can include single-mode optical communication systems (only one mode of optical signal can be transmitted), and few-mode optical communication System (can transmit multiple modes of optical signals); when divided according to the scope of application, it can include public optical communication systems (usually refer to optical communication systems applied to telecom operators), and dedicated optical communication systems (usually refer to optical communication systems applied to Optical communication systems of units other than telecom operators, such as optical communication systems used in the transportation field and electric power field, etc.).
  • Figure 1 is a schematic structural diagram of a possible optical communication system applicable to the embodiment of the present application.
  • the system architecture shown in Figure 1 includes an electrical transmitter, an optical transmitter, at least one optical fiber, at least one optical repeater, Optical receivers, and electrical receivers, etc.
  • the electrical transmitter or electrical receiver can usually be a terminal device or a switch.
  • the electrical transmitter is used to send a pulse code modulated electrical signal. After the pulse code modulated electrical signal is sent to the optical transmitter, the optical transmitter can send the pulse The code-modulated electrical signal is converted into an optical pulse signal and then coupled to an optical fiber for transmission.
  • the optical transmitter may include a semiconductor light source capable of completing electrical-optical conversion, such as a semiconductor laser or a semiconductor light-emitting diode.
  • the optical receiver can convert the optical pulse signal into an electrical signal, and then restore it to the original pulse signal after amplifying and other processing operations on the electrical signal.
  • the code modulates the electrical signal and sends it to the electrical receiver.
  • the optical receiver may include a photodetector capable of completing photoelectric conversion, such as a photodiode.
  • optical repeaters can generally have two forms, one is a repeater in the form of optical-electrical-optical conversion, and the other is an optical amplifier that directly amplifies optical signals. These two forms of optical repeaters All devices can increase the power of the optical pulse signal, so that the optical pulse signal can be transmitted to a longer distance. For example, assuming that there are 20 optical fibers in Figure 1, and the distance of each optical fiber is 80 kilometers, the optical communication system can transmit the optical pulse signal sent by the optical transmitter to the optical receiver at a distance of 1600 kilometers.
  • the optical pulse signal transmitted on the entire optical fiber link is likely to be interrupted on this section of optical fiber, which will affect the communication quality of the entire optical communication system. . Therefore, in an optical communication system, accurate measurement of the transmission performance of an optical fiber link plays a vital role in the high-quality transmission of optical pulse signals.
  • the present application provides an optical fiber measurement solution, which is used to install an optical time domain reflectometer at one or both ends of one or more optical fibers in an optical communication system, so as to realize the measurement of one or more optical fibers One-way or two-way measurement of performance, timely discovering problematic fibers in optical communication systems.
  • Stimulated scattering of light stimulated Raman scattering and stimulated Brillouin scattering.
  • the high-intensity laser when the high-intensity laser passes through the optical fiber, it interacts strongly with the material molecules in the optical fiber, so that the scattering process has the property of stimulated emission.
  • This nonlinear optical effect is called light stimulation.
  • Scattering effect Stimulated scattering of light usually also exhibits a threshold characteristic, that is, like a laser, it can only be produced under appropriate optical power.
  • the following two types of stimulated scattering usually occur in optical fibers:
  • Stimulated Raman scattering is the result of the interaction between the pump light in the optical fiber and the vibration of silicon atoms, and it is mainly manifested in the transfer of the power of short-wavelength light to the power of long-wavelength light. Affected by stimulated Raman scattering, the power of short-wavelength light will be attenuated, resulting in the optical signal noise ratio (optical signal noise ratio, OSNR) of short-wavelength light (refers to the optical signal within the effective bandwidth of 0.1nm, The ratio of the power to the power of the noise signal) decreases, while the power of long-wavelength light increases, resulting in enhanced nonlinear interference.
  • OSNR optical signal noise ratio
  • the occurrence threshold of stimulated Raman scattering is small, and it is related to the material, type and parameters of the fiber.
  • the pump light power transmitted in the fiber exceeds the occurrence threshold of stimulated Raman scattering in the fiber, the pump The Pu light can interact with the silicon atoms in the optical fiber to generate stimulated Raman scattering.
  • Stimulated Brillouin scattering is the result of the interaction between the pump light and the phonon vibration in the optical fiber, which is mainly manifested as causing crosstalk between channels and loss of channel energy.
  • Stimulated Brillouin scattering usually produces a frequency shift of the pump light, that is, it excites scattered light of another wavelength different from that of the pump light, and the offset between the other wavelength and the original wavelength is determined by the propagation constant in the fiber and material constants, and can also be obtained a priori through experiments.
  • the occurrence threshold of stimulated Brillouin scattering is higher than that of stimulated Raman scattering. For the pump light of 1550nm, when the power of the pump light reaches 7-8dBm, the pump light can be mixed with the optical fiber. Stimulated Brillouin scattering due to phonon interaction.
  • OTDR Optical time-domain reflectometer
  • the optical time domain reflectometer is made according to the principle of backscattering of pump light and Fresnel inversion, and the backscattering light generated when the pump light propagates in the optical fiber is usually used to obtain the optical fiber
  • the attenuation information of the fiber can be used to measure fiber attenuation, joint loss, locate fiber fault points, and understand the loss distribution of the fiber along the length, etc.
  • OTDR there are mainly two types of OTDR in the industry, that is, an OTDR that emits only one measurement light, and an OTDR that emits two measurement lights simultaneously.
  • This application mainly utilizes an optical time domain reflectometer that emits two measurement lights at the same time to complete the optical fiber measurement.
  • the specific structure of the optical time domain reflectometer please refer to the description in Embodiment 1 below, and no introduction will be made here.
  • a multi-core optical fiber refers to an optical fiber that contains multiple cores in an optical fiber.
  • a multi-core optical fiber can simultaneously transmit optical signals through multiple cores, which helps to improve the transmission efficiency of optical signals and the amount of transmitted signals. .
  • a few-mode fiber refers to an optical fiber capable of simultaneously transmitting signal streams of multiple modes in one fiber, and is also called a multi-mode fiber.
  • Few-mode fiber is a kind of single-core fiber. Compared with ordinary single-mode single-core fiber, few-mode fiber can have a larger mode field area and allow parallel transmission of different modes of information in several independent spaces. flow, which helps to increase the communication capacity of optical fibers.
  • Wavelength Division Multiplexing (WDM).
  • wavelength division multiplexing refers to the technology of combining two or more optical carriers with different wavelengths at the sending end and then coupling them into the same optical fiber for transmission.
  • the multiplexer separates the combined optical carriers of various wavelengths.
  • Dense wavelength division multiplexing (dense wavelength division multiplexing, DWDM) is a special case of wavelength division multiplexing, which is usually used to combine two or more optical carriers of different wavelength bands into the same optical fiber, so that A plurality of mutually orthogonal optical carriers that are closely arranged are transmitted on the domain, and the wavelength interval of multiple optical carriers is much smaller than that of non-intensive wavelength division multiplexing.
  • DWDM can transmit more optical carriers in the same transmission window, which helps to improve bandwidth utilization.
  • Wavelength division multiplexing usually uses a certain wavelength interval to send multiple optical carriers, each optical carrier occupies a wavelength width, and the central wavelength can be considered as the average wavelength of the minimum wavelength and maximum wavelength among multiple optical carriers. For example, assuming that optical carriers within the wavelength range of 1530nm-1565nm are sent at a wavelength interval of 0.4nm, a total of 80 optical carriers can be sent. If the minimum wavelength of the 80 optical carriers is 1530nm and the maximum wavelength is 1565nm, then the center The wavelength is the average wavelength of 1530nm and 1565nm, which is 1547.5nm.
  • an embodiment of the present application provides an optical fiber measurement system, which is used to send signal light and two measurement lights on both sides of the wavelength of the signal light to the optical fiber simultaneously and in the same direction, so that the normal service of the optical fiber is not affected.
  • the power transfer between the two measurement lights and the signal light should be offset as much as possible to improve the accuracy of the measurement results.
  • connection in the following embodiments of the present application refers to electrical connection, and the connection of two electrical components may be a direct or indirect connection between two electrical components.
  • connection between A and B can be directly connected between A and B, or indirectly connected between A and B through one or more other electrical components, such as the connection between A and B, or the direct connection between A and C.
  • C and B are directly connected, and A and B are connected through C.
  • the communication terminal hereinafter refers to a port that can be used as both an input terminal and an output terminal.
  • the communication terminal is only an exemplary name, and it can also have other names in other schemes, for example, it can also be called an input terminal. / output terminal, the specific is not limited.
  • Fig. 2 exemplarily shows a schematic diagram of the architecture of an optical fiber measurement system provided by an embodiment of the present application.
  • the system architecture includes a signal generator 100, an optical time domain reflectometer) and wavelength division multiplexer 300, the signal generator 100 in this example may correspond to the optical transmitter in FIG. 1 .
  • the output terminal of the signal generator 100 is connected to the communication terminal a 1 of the wavelength division multiplexer 300
  • the communication terminal c of the optical time domain reflectometer 200 is connected to the communication terminal a 2 of the wavelength division multiplexer 300
  • the wavelength division multiplexer The communication end a3 of 300 is connected to an optical fiber.
  • the signal generator 100 can send signal light to the communication terminal a 1 of the wavelength division multiplexer 300; the optical time domain reflectometer 200 can send the wavelength to the communication terminal a 2 of the wavelength division multiplexer 300
  • the first measurement light of ⁇ 1 and the second measurement light of wavelength ⁇ 2 , and ⁇ 1 and ⁇ 2 are respectively located on both sides of the wavelength of the signal light, for example, ⁇ 1 is greater than the wavelength of the signal light and ⁇ 2 is smaller than the wavelength of the signal light wavelength, or ⁇ 1 is less than the wavelength of the signal light and ⁇ 2 is greater than the wavelength of the signal light
  • the wavelength division multiplexer 300 can receive the signal light from the communication terminal a 1 and the first measurement received from the communication terminal a 2
  • the light and the second measurement light are combined and processed, and the combined light is sent to the optical fiber through the communication terminal a3, and the light returned when the combined light is transmitted in the optical fiber is received through the communication terminal a3 , and The returned light is sent to the optical
  • the wavelength ⁇ 1 of the first measurement light is greater than the wavelength of the signal light
  • the wavelength ⁇ 2 of the second measurement light is smaller than the wavelength of the signal light
  • the signal light can be single-wavelength signal light or multi-wavelength signal light:
  • the wavelength ⁇ 1 of the first measurement light can be a wavelength greater than 1530nm, such as 1550nm
  • the wavelength ⁇ 2 of the second measurement light can be a wavelength less than 1530nm, such as 1500nm.
  • the power of 1500nm measurement light will be transferred to 1530nm signal light, and the power of 1530nm signal light will be transferred to 1550nm Measuring light transfer, as long as the wavelengths of the 1500nm measuring light and 1550nm measuring light are set reasonably (for example, the wavelength difference between the two measuring lights and the signal light is set to be the same), the power of the signal light transferred into 1530nm and the signal light of 1530nm transferred out The power can cancel each other with a high probability.
  • this method can not only be measured during the normal transmission of signal light, but also help to eliminate the impact of the measurement process on the normal service signal transmission of signal light.
  • the power transfer of the 1500nm measurement light and the power transfer of the 1550nm measurement light both have an impact on the returned light
  • the wavelength ⁇ 1 of the first measurement light can be a wavelength greater than the maximum wavelength 1555nm in the multi-wavelength, such as 1570nm, and the wavelength ⁇ 2 of the second measurement light can be It is one wavelength smaller than the minimum wavelength of 1530 nm among the multiple wavelengths, for example, 1500 nm.
  • the power of the 1500nm measurement light will be transferred to the 1530nm signal light, while the power of the 1530nm signal light It will shift to the 1555nm signal light, and the power of the 1555nm signal light will shift to the 1570nm measurement light.
  • the 1500nm measurement light will be transferred into the 1530nm signal
  • the power of the light and the power of the 1555nm signal light transferred to the 1570nm measurement light can cancel each other, which helps to improve the accuracy of the measurement while reducing the impact of the measurement process on the normal transmission of the two signal lights.
  • multi-wavelength signal light also has power transfer during normal service transmission. This measurement only offsets the power transferred into the 1530nm signal light and the power transferred out of the 1555nm signal light, and does not affect the two signals.
  • the power transfer generated between lights that is to say, this measurement method can also accurately measure the measurement results affected by the power transfer of the signal light itself, and the measurement results can accurately represent the real transmission scene.
  • the multi-wavelength signal light may be located in one wavelength band range, or may be located in multiple wavelength band ranges.
  • the signal generator 100 may include K signal generating units (signal generating unit 1 as shown in FIG. 2, signal generating unit 2, ... , signal generating unit K, K is a positive integer greater than or equal to 2), K signal generating units correspond to K bands one by one, and the output ends of K signal generating units can be respectively connected to the communication end of the wavelength division multiplexer 300 a 1 , each signal generating unit is used to send signal light within the corresponding wavelength band to the wavelength division multiplexer 300 .
  • the K bands can be selected from the following bands: O band (wavelength range 1260nm-1360nm), E band (wavelength range 1360nm-1460nm), S band (wavelength range 1460nm-1530nm), C band (wavelength range range of 1530nm-1565nm), L-band (wavelength range of 1565nm-1625nm), etc.
  • O band wavelength range 1260nm-1360nm
  • E band wavelength range 1360nm-1460nm
  • S band wavelength range 1460nm-1530nm
  • C band wavelength range range range of 1530nm-1565nm
  • L-band wavelength range of 1565nm-1625nm
  • optical fiber measurement scheme in this application is not only applicable to the measurement of optical fibers transmitting single-wavelength signals, but also applicable to the measurement of optical fibers transmitting multi-band mixed signals. Scattering effects will become more and more obvious, so the accuracy of measurement results can be effectively improved by using optical fiber measurements that can counteract power transfer in optical communication systems that transmit multi-band mixed signals.
  • the wavelength ⁇ 1 of the first measurement light and the maximum wavelength (assumed to be ⁇ max ) of the signal light correspond to the single wavelength of the above-mentioned single-wavelength signal light or the maximum wavelength of the above-mentioned multi-wavelength signal light , or the wavelength difference ⁇ 1 - ⁇ max of the signal light in the maximum wavelength band among the signal lights of the above-mentioned multiple bands), and the minimum wavelength of the signal light (assumed to be ⁇ min , corresponding to the single wavelength of the above-mentioned single-wavelength signal light wavelength, or the minimum wavelength of the above-mentioned multi-wavelength signal light, or the minimum wavelength of the signal light in the minimum wavelength band among the above-mentioned multiple band signal lights) and the wavelength ⁇ 2 of the second measurement light.
  • the preset Raman gain range is the maximum wavelength difference that causes two optical signals with different wavelengths to produce obvious stimulated Raman scattering effect, and can usually be set to a value between 90nm-110nm.
  • the wavelength ⁇ 1 of the first measurement light can be set to be greater than 1555nm and not greater than 1655nm
  • the wavelength of the second measurement light ⁇ 2 can be set to a wavelength greater than 1430nm and not less than 1530nm, to ensure that both the first measurement light and the second measurement light can have power transfer with the signal light, and improve the ability of mutually canceling the power transfer probability.
  • the instrument 200 when the wavelength difference between the two measurement lights and the signal light is within the preset Raman gain range, the two measurement lights will undergo power transfer with the signal light, and the optical time domain reflection
  • the instrument 200 receives the returned light sent by the wavelength division multiplexer 300, it can also obtain the first returned light corresponding to the first measurement light and the second returned light corresponding to the second measurement light from the returned light, according to The first return light and the second return light determine the properties of the fiber.
  • determining the performance of the optical fiber may include: the processor obtains a first performance curve corresponding to the optical fiber according to the first return light, obtains a second performance curve corresponding to the optical fiber according to the second return light, and then weights the first performance curve and the second performance curve The second performance curve is to obtain the target performance curve of the optical fiber.
  • the first performance curve corresponds to the first measurement light after the power is turned in
  • the second performance curve corresponds to the second measurement light after the power is turned out.
  • the influence of the power transferred in and the power transferred out of the second measuring light can also be set according to the correlation relationship between the power transferred in of the first measuring light and the power transferred out of the second measuring light to set the corresponding weight and sum of the first performance curve
  • the correlation of the weights corresponding to the second performance curve for example, setting a larger weight for the performance curve corresponding to the measurement light with more power transferred in or out, and setting a larger weight for the performance curve corresponding to the measurement light with less power transferred in or out
  • a smaller weight to try to make the weighted two performance curves correspond to a positive and negative power transfer with the same value.
  • the relative frequency of the two optical signals refers to the frequency difference between the frequencies of the two signals.
  • FIG. 3 exemplarily shows a corresponding relationship between power transfer and relative frequency provided by the embodiment of the present application. As shown in FIG. 3 , when the relative frequency of optical signal 1 and optical signal 2 is 0, optical signal 1 and optical signal 2 Signal 2 has the same wavelength, and no power transfer occurs between optical signal 1 and optical signal 2.
  • the relative frequency of optical signal 1 relative to optical signal 2 When the relative frequency of optical signal 1 relative to optical signal 2 is positive, the frequency of optical signal 1 is higher than that of optical signal 2, and the wavelength of optical signal 1 is smaller than that of optical signal 2. 2 transfer power, and the greater the relative frequency of optical signal 1 relative to optical signal 2, the smaller the wavelength of optical signal 1 compared to the wavelength of optical signal 2, and the more power transferred from optical signal 1 to optical signal 2. For example, referring to FIG.
  • the relative frequency of optical signal 1 to optical signal 2 When the relative frequency of optical signal 1 to optical signal 2 is a negative value, the frequency of optical signal 1 is smaller than that of optical signal 2, the wavelength of optical signal 1 is larger than that of optical signal 2, and optical signal 2 will 1 transfer power, and the smaller the value of the relative frequency of optical signal 1 relative to optical signal 2, the greater the wavelength of optical signal 1 is compared to the wavelength of optical signal 2, and the more optical signal 2 will transfer to optical signal 1 power.
  • the relative frequency of optical signal 1 relative to optical signal 2 when the relative frequency of optical signal 1 relative to optical signal 2 is - ⁇ f 21 , the power transferred from optical signal 2 to optical signal 1 is ⁇ G 21 .
  • the power transferred from the optical signal 2 to the optical signal 1 is ⁇ G 22
  • ⁇ f 21 is smaller than ⁇ f 22
  • the corresponding ⁇ G 21 is also smaller than ⁇ G 22 . It can be seen that the power transferred between two optical signals is actually positively correlated with the relative frequencies of the two optical signals.
  • the weights corresponding to the first performance curve and the weights corresponding to the second performance curve according to the correlation between the power transfer-in of the first measurement light and the power transfer-out of the second measurement light, it is also possible to set the first
  • the ratio of the weight of the performance curve to the weight of the second performance curve is proportional to the ratio of the relative frequency of the signal light relative to the first measurement light and the relative frequency of the second measurement light relative to the signal light.
  • the relative frequency of the signal light relative to the first measurement light refers to the center frequency of the signal light (corresponding to the single frequency of the above-mentioned single-wavelength signal light, or the center frequency of the above-mentioned multi-wavelength signal light, similar to the center wavelength, multi-wavelength
  • the center frequency of the signal light corresponds to the frequency difference between the minimum frequency and the maximum frequency in the multi-wavelength signal light) and the frequency of the first measurement light
  • the relative frequency of the second measurement light relative to the signal light refers to the second measurement light The frequency difference between the frequency and the frequency of the signal light.
  • the weight corresponding to the first performance curve can try to make up for the lack of signal caused by the transfer of more power of the second measurement light to the side of the signal light, and can also slow down the transfer of more power of the signal light to the side of the first measurement light.
  • the resulting signal excess helps equalize both the first performance curve and the second performance curve to the same power transfer value.
  • the optical time domain reflectometer can determine the performance of the optical fiber in a weighted manner.
  • the weighting calculation method is simpler and easier to implement, which helps to improve measurement efficiency.
  • the ratio of the weight of the first performance curve to the weight of the second performance curve can be set, which is equal to the ratio of the signal light to the first The relative frequency of the measurement light and the ratio of the relative frequency of the second measurement light to the signal light.
  • the ratio of "setting the weight of the first performance curve to the weight of the second performance curve" in the above content is proportional to the relative frequency of the signal light relative to the first measurement light and the relative frequency of the second measurement light relative to the signal light
  • the ratio of the relative frequency of the first performance curve" can also be, the ratio of the weight of the first performance curve to the weight of the second performance curve is set, which is proportional to the relative wavelength of the first measurement light relative to the signal light and the relative wavelength of the signal light relative to the second measurement The ratio of the relative wavelengths of light.
  • the relative wavelength of the first measurement light with respect to the signal light refers to the wavelength ⁇ 1 of the first measurement light and the center wavelength of the signal light (corresponding to the single wavelength of the above-mentioned single-wavelength signal light, or the center wavelength of the above-mentioned multi-wavelength signal light ), the relative wavelength of the signal light relative to the second measurement light is the wavelength difference between the central wavelength of the signal light and the wavelength ⁇ 2 of the second measurement light.
  • the frequency differences obtained by the frequency of the first measurement light are all positive values, that is, the relative wavelength of the first measurement light relative to the signal light, and the relative frequency of the signal light relative to the first measurement light are both positive values.
  • the wavelength difference obtained by subtracting the wavelength of the second measurement light from the wavelength of the signal light and the second The frequency difference obtained by subtracting the frequency of the signal light from the frequency of the measurement light is positive, that is, the relative wavelength of the signal light relative to the second measurement light, and the relative frequency of the second measurement light relative to the signal light are also positive. value. It can be seen that this solution sets the relative wavelength or relative frequency of the positive value with reference to the actual situation of the wavelength or frequency, which can facilitate the direct setting of the weight of the first performance curve and the weight of the second performance curve by referring to the ratio of the two positive values.
  • the absolute value of the relative frequency of the signal light and the two first measurement lights can also be obtained directly, and the two performance curves can be set according to the ratio of the two absolute values. weight, or directly obtain the absolute values of the relative wavelengths of the signal light and the two first measurement lights, and set the weights of the two performance curves according to the ratio of the two absolute values.
  • the first performance curve and the second performance curve can correspond to the same weight, For example, both are 0.5.
  • the optical time domain reflectometer 200 determines the first performance curve according to the first return light corresponding to the first measurement light, and determines the second performance curve according to the second return light corresponding to the second measurement light, it can also directly sum first performance
  • This calculation method is relatively simple, easy to implement, and can effectively improve measurement efficiency.
  • the optical time domain reflectometer may be an optical time domain reflectometer with any structure capable of generating measurement light of two different wavelengths.
  • a multiplexer 230 a circulator 240 , a demultiplexer 250 , a first detector 261 , a second detector 262 and a processor 270 .
  • the output end of the first laser 211 is connected to the input end of the first pulse modulator 221, the output end of the first pulse modulator 221 is connected to the first input end of the multiplexer 230, and the output end of the second laser 212 is connected to the second
  • the input end of the pulse modulator 222, the output end of the second pulse modulator 222 is connected to the second input end of the multiplexer 230, the output end of the multiplexer 230 is connected to the input end b1 of the circulator 240, the communication of the circulator 240
  • the terminal b2 is connected to the communication terminal c of the optical time domain reflectometer 200
  • the output terminal b3 of the circulator 240 is connected to the input terminal of the demultiplexer 250
  • the first output terminal of the demultiplexer 250 is connected to the input terminal of the first detector 261
  • the second output end of the wave splitter 250 is connected to the input end of the second detector 262
  • the output end of the first detector 261 is connected to the first input end
  • the first laser 211 can output a direct current light with a wavelength of ⁇ 1, and after entering the first pulse modulator 221, the direct current light is modulated into the first measurement light in the form of a pulse with a wavelength of ⁇ 1 (pulse width and transmission period not limited), and then sent to the multiplexer 230.
  • the second laser 212 can output wavelength as the direct current light of ⁇ 2 , after this direct current light enters the second pulse modulator 222, be modulated into the second measurement light of the pulse form of wavelength ⁇ 2 (pulse width and transmission period are not limited), Furthermore, it is also sent to the multiplexer 230 .
  • the multiplexer 230 combines the first measurement light with a wavelength of ⁇ 1 and the second measurement light with a wavelength of ⁇ 2 into a dual-wavelength measurement optical signal, and sends the dual-wavelength measurement optical signal to the input port b of the circulator 240 1 , output to the wavelength division multiplexer 300 via the communication port b2 of the circulator 240, and then combined with the signal light output by the signal generator 100 in the wavelength division multiplexer 300, and coupled into the optical fiber simultaneously and in the same direction.
  • the return light generated by the transmission of the dual -wavelength measurement optical signal in the optical fiber returns to the communication terminal a3 of the wavelength division multiplexer 300 along the opposite direction of the input direction, and then is output through the communication terminal a2 of the wavelength division multiplexer 300
  • the communication terminal b 2 to the circulator 240 is output to the wave splitter 250 via the output terminal b 3 of the circulator 240 .
  • the wave splitter 250 demultiplexes the return light into first return light corresponding to the first measurement light and second return light corresponding to the second measurement light, and sends the first return light to the first detector 261, and the first detector 261 261 is converted into a first analog electrical signal and then sent to the processor 270, and the second return light is sent to the second detector 262, which is converted into a second analog electrical signal by the second detector 262 and sent to the processor 270.
  • the processor 270 samples the first analog electrical signal to obtain a discrete first performance curve, samples the second analog electrical signal to obtain a discrete second performance curve, and then corresponds to the second performance curve according to the weight corresponding to the first performance curve The weight of the two performance curves is weighted and averaged to obtain the target performance curve.
  • the performance curve of the optical fiber may specifically be a power attenuation variation curve.
  • Fig. 4 exemplarily shows a schematic diagram of a power attenuation curve of an optical fiber.
  • the measurement light will be transmitted along the optical fiber from one end of the optical fiber to At the other end, when it is transmitted to each position, it is affected by the medium material of each position to generate return light and returns to the optical time domain reflectometer 200. Since the speed of light is fixed, the reflections collected by the optical time domain reflectometer 200 at different times The power of the reflected light is actually the power loss at different positions of the fiber.
  • the optical time domain reflectometer 200 after the optical time domain reflectometer 200 emits two measurement lights, it can receive the return light corresponding to each measurement light in real time, and construct a power attenuation according to the return light at different times corresponding to each measurement light change curve, the target power change curve as shown in FIG. 4 is obtained after weighting the two power change curves.
  • the position of the problem in the optical fiber can be known.
  • the power at position P1 on the optical fiber in Figure 4 corresponds to a sudden increase of 0.02dB. This sudden increase indicates that there may be a change in the core area of the optical fiber at position P1.
  • the corresponding power drop at point P2 on the optical fiber in Figure 4 is 0.12dB, which indicates that there may be a lossy splicing at position P2.
  • the return light corresponding to the measurement light can be the return light with the same wavelength as the measurement light (for example, when the return light is caused by Rayleigh scattering, the scattering process will not affect the measurement light. wavelength, that is, the return light and the measurement light have the same wavelength), or the return light with a certain deviation from the wavelength of the measurement light (for example, when the return light is caused by Brillouin scattering, the scattering process will excite
  • the new optical carrier with different wavelengths, that is, the return light and the measurement light can have different wavelengths), of course, it can also include two or more types that have the same wavelength as the measurement light and have a certain deviation from the wavelength of the measurement light of the return light (simultaneous excitation of Rayleigh scattering and Brillouin scattering).
  • the first laser 211 and the second laser 212 may also have a wavelength-tunable function.
  • the first laser 211 and the second laser 212 can also be connected to the processor 270, and the processor 270 can also control the first laser 211 and the second laser 212 multiple times to emit DC light under various wavelength combinations, and collect The return light under each wavelength combination obtains the target performance curve under each wavelength combination, and then integrates multiple target performance curves under multiple wavelength combinations to determine the final target performance curve, for example, the average performance curve of multiple target performance curves as the final target performance curve.
  • the final measurement result obtained by integrating the measurement results of multiple measurements can not only make the measurement result more convincing, but also avoid the accidental error in determining the performance by only one measurement, and help to further improve the accuracy of the measurement result sex.
  • OTDR 200 shown in FIG. 2 is just an example, and in practice, some deformations can also be made to the OTDR 200 shown in FIG. 2 to obtain a new OTDR instrument.
  • a filter can also be set between the wave splitter 250 and the first detector 261, and between the wave splitter 250 and the second detector 262, first use the filter to filter out each chain After the measured light transmitted on the road corresponds to light of wavelengths other than the returned light, the filtered returned light is sent to the processor 270, so as to improve the purity of the input signal used by the processor 270 to construct the performance curve.
  • a polarization switch can also be provided between the first pulse modulator 221 and the multiplexer 230, and between the second pulse modulator 222 and the multiplexer 230, first use the polarization switch to pair each pulse After the measurement light modulated by the modulator is corrected, the deviation-corrected measurement lights are combined.
  • a pulse generator can also be set, one end of the pulse generator is connected to the first pulse modulator 221 and the second pulse modulator 222, and the other end of the pulse generator is connected to the processor 270, and the processor 270 It is also possible to first instruct the pulse generator to generate the required pulse form, and then send the pulse form to the pulse modulator via the pulse generator to perform pulse modulation of the measurement light, and the first pulse modulator 221 or the second pulse modulator 222 may also notify the processor 270 of the modulation result through the pulse generator after completing the pulse modulation of the measurement light, so that the processor 270 and the two pulse modulators can maintain time synchronization. It should be understood that any optical time domain reflectometer with any structure capable of generating measurement lights of two different wavelengths is within the scope of protection of this application, and this application will not introduce them one by one.
  • the power of the short-wavelength measuring light can be transferred to the side of the signal light, and the power of the signal light can be transferred to the side of the long-wavelength measuring light.
  • the measurement light is transferred on one side, and the return light of the two measurement lights is used to comprehensively determine the performance of the optical fiber, which helps to offset the power transfer of the two measurement lights in the measurement results and effectively eliminate the interference of the stimulated scattering effect on the measurement process. It helps to improve the accuracy of measurement results without affecting the normal transmission service of signal light.
  • the scheme of transmitting two measuring light and signal light in the same direction can also enable the optical time domain reflectometer to calculate the performance of the optical fiber using a weighted method.
  • the weighting method is simple to calculate and easy to implement, so it also helps to improve the efficiency of optical fiber measurement .
  • Embodiment 2 Based on Embodiment 2 to Embodiment 4, the application of the optical fiber measurement system in Embodiment 1 in different scenarios is further introduced below.
  • Figure 5 exemplarily shows a schematic diagram of the architecture of a measurement C+L wavelength division multiplexing system provided by an embodiment of the present application.
  • the C+L wavelength division multiplexing system may include at least Two optical fibers, such as optical fiber 1 and optical fiber 2, may also include a signal generator 100, a wavelength division multiplexer 310, a wavelength division multiplexer 410, a C-band amplifier 511, an L-band amplifier 512, a wavelength division multiplexer 320, wave division multiplexer 420 and signal receiver 600 .
  • the signal generator 100 in this example can correspond to the optical transmitter in Figure 1
  • the signal receiver 600 can correspond to the optical receiver in Figure 1
  • the C-band amplifier 511 and the L-band amplifier 512 can be set in Figure 1 in the optical repeater.
  • the signal generator 100 may include a C-band signal generating unit 110 and an L-band signal generating unit 120
  • the signal receiver 600 may include a C-band signal receiving unit 610 and an L-band signal receiving unit 620 .
  • the output end of the C-band signal generation unit 110 is connected to the input end a11 of the wavelength division multiplexer 310, the output end of the L-band signal generation unit 120 is connected to the input end a12 of the wavelength division multiplexer 310, and the wavelength division multiplexer 310
  • the communication end a 13 of the optical fiber 1 is connected to one end of the optical fiber 1; the other end of the optical fiber 1 is connected to the communication end a 21 of the wave division multiplexer 410, and the output end a 22 of the wave division multiplexer 410 is connected to the input end of the C-band amplifier 511.
  • the output terminal a23 of the demultiplexer 410 is connected to the input terminal of the L-band amplifier 512, the output terminal of the C-band amplifier 511 is connected to the input terminal a31 of the wavelength division multiplexer 320, and the output terminal of the L-band amplifier 512 is connected to the WDM
  • the input end a 32 of the multiplier 320 , the communication end a 33 of the wavelength division multiplexer 320 is connected to one end of the optical fiber 2;
  • the output terminal a 42 of the wave division multiplexer 420 is connected to the input terminal of the L-band signal receiving unit 620.
  • the C-band signal generation unit 110 can send the C-band signal light within the wavelength range of 1530nm-1565nm to the wavelength division multiplexer 310, and the L-band signal generation unit 120 can send the wavelength division multiplexer 310 to the wavelength division multiplexer 310.
  • the use device 310 sends the L-band signal light within the wavelength range of 1565nm-1625nm, the wavelength division multiplexer 310 performs multiplexing processing on the C-band signal light and the L-band signal light, and couples the multiplexed signal light into the optical fiber 1, Then it is transmitted to the wave division multiplexer 410 in the optical fiber 1 .
  • the wave division multiplexer 410 decouples the waved signal light, obtains the C-band signal light and transmits it to the C-band amplifier 511 for amplification, obtains the L-band signal light and transmits it to the L-band amplifier 512 for amplification.
  • the amplified C-band signal light and the amplified L-band signal light enter the wavelength division multiplexer 320, and the wavelength division multiplexer 320 performs multiplexing processing, and couples the multiplexed signal light into the optical fiber 2, and then in The optical fiber 2 is transmitted to the wave division multiplexer 420.
  • the wave division multiplexer 420 decouples the waved signal light, obtains the C-band signal light and sends it to the C-band signal receiving unit 610 , obtains the L-band signal light and sends it to the L-band signal receiving unit 620 .
  • the embodiment of this application can measure any optical fiber or any number of optical fibers in the C+L wavelength division multiplexing system:
  • an optical time domain reflectometer 210 may also be included in the C+L wavelength division multiplexing system, and the optical time domain reflectometer 210 is connected to the communication terminal a 14 of the wavelength division multiplexer 310 for sending to the wavelength division multiplexer
  • the user 310 transmits two kinds of measurement lights with wavelengths ⁇ 11 and ⁇ 12 .
  • the C-band signal light emitted by the C-band signal generating unit 110, the L-band signal light emitted by the L-band signal generating unit 120, and the measurement light of two wavelengths emitted by the optical time domain reflectometer 210 will enter simultaneously and in the same direction.
  • the wavelength division multiplexer 310 is coupled into the optical fiber 1 after being multiplexed by the wavelength division multiplexer 310, and the return light generated when the multiplexed optical signal is transmitted in the optical fiber 1 returns to the optical fiber 1 through the wavelength division multiplexer 310 A time domain reflectometer 210, so that the optical time domain reflectometer 210 determines the performance of the optical fiber 1 according to the calculation method in the first embodiment above;
  • an optical time domain reflectometer 220 may also be included in the C+L wavelength division multiplexing system, and the optical time domain reflectometer 220 is connected to the communication terminal a 34 of the wavelength division multiplexer 320 for sending to the wavelength division multiplexer.
  • the user 320 transmits two kinds of measurement lights with wavelengths ⁇ 21 and ⁇ 22 . In this way, the amplified C-band signal light sent by the C-band amplifier 511, the L-band signal light sent by the L-band amplifier 512, and the measurement light of two wavelengths sent by the optical time domain reflectometer 220 will enter the wave simultaneously and in the same direction.
  • the division multiplexer 320 is coupled into the optical fiber 2 after being multiplexed by the wavelength division multiplexer 320, and the return light generated when the multiplexed optical signal is transmitted in the optical fiber 2 returns to the optical fiber 2 through the wavelength division multiplexer 320 A domain reflectometer 220, so that the optical time domain reflectometer 220 determines the performance of the optical fiber 2 according to the calculation method in the first embodiment above;
  • the C+L wavelength division multiplexing system can also include an optical time domain reflectometer 210 and an optical time domain reflectometer 220 at the same time, and the optical time domain reflectometer 210 is used to measure the optical fiber 1.
  • the time domain reflectometer 220 is used to measure the optical fiber 2 .
  • a wave-division multiplexer 410 is provided at the connection between the optical fiber 1 and the optical fiber 2, the wave-division multiplexer 410 can decompose the signal light of two wavelength bands from the signal transmitted by the optical fiber 1 and send them to the respective amplifiers.
  • the wavelengths ⁇ 11 and ⁇ 12 of the two kinds of measuring light emitted by the optical time domain reflectometer 210 and the wavelengths ⁇ 21 and ⁇ 22 of the two measuring lights emitted by the optical time domain reflectometer 220 may be the same or different. limited.
  • This measurement scheme can not only measure the optical fiber 1 at the transmission end, but also measure the optical fiber 2 at the middle span. By placing an optical time domain reflectometer at one end of each span of optical fiber, the optical time domain reflectometer can be completed. Unidirectional measurement of the performance of each fiber segment in the system.
  • the C+L wavelength division multiplexing system may also include an optical time domain reflectometer 210 and an optical time domain reflectometer 230, The optical time domain reflectometer 210 and the optical time domain reflectometer 230 are respectively located at two ends of the optical fiber 1 .
  • the optical time domain reflectometer 210 is connected to the communication end a14 of the wavelength division multiplexer 310 located at the left end of the optical fiber 1 shown in the figure (the upstream end of the optical fiber 1 is shown in the figure, that is, the end receiving signal light), It is used to send two kinds of measurement lights with wavelength ⁇ 11 and wavelength ⁇ 12 to the wavelength division multiplexer 310, and the optical time domain reflectometer 230 is connected to the right end of the optical fiber 1 diagram (shown in the figure is optical fiber 1
  • the communication end a 24 of the wave division multiplexer 410 at the downstream end of the signal light that is, the end that sends out the signal light, is used to send two kinds of measurement light with a wavelength of ⁇ 31 and a wavelength of ⁇ 32 to the wave division multiplexer 410.
  • the two kinds of measurement light energy emitted by the optical time domain reflectometer 210 can be coupled into the upstream of the optical fiber 1 in the same direction as the signal light through the wavelength division multiplexer 310, so that the optical time domain reflectometer 210 can obtain from the optical fiber 1 according to the return light.
  • the first target performance curve measured at the upstream node of 1 (as shown in (A) in Figure 6); Direct coupling from the downstream of the optical fiber 1 into the optical fiber 1, so that the optical time domain reflectometer 230 obtains the second target performance curve measured from the downstream node of the optical fiber 1 according to the returned light (as shown in (B) in FIG. 6 ).
  • the two-way measurement of the optical fiber can be completed by two optical time domain reflectometers, and the loss information of each position in the optical fiber in two directions can be obtained. It not only helps to quantify the loss more accurately, but also accurately locates the problems existing in the optical fiber (including but not limited to the specific cause of damage at the fiber extrusion, lossy connector or splicing of fibers with different core diameters), and improves the accuracy and accuracy of measuring optical fibers.
  • the degree of detail can also cover the test blind area existing in the measurement of a single direction through the measurement of two directions, effectively expanding the effective range of measurement. For example, referring to Fig. 6 (A) and Fig.
  • the position P1 in the optical fiber has a sudden increase of +0.02dB power loss when measured along the direction from left to right in the figure, and there is a power loss along the When measuring from right to left as shown in the figure, there is a power loss of -0.08dB. According to this positive and negative power loss, it can be accurately located that there may be a problem of fiber extrusion at position P1.
  • position P2 in the fiber exhibits a power loss dip of -0.12dB when measured along the direction shown from left to right, and a dip of -0.02dB when measured along the direction shown from right to left
  • the power loss in dB according to the two negative power losses, it can be accurately located that there may be an optical fiber splicing problem at position P2.
  • the wavelengths ⁇ 11 and ⁇ 12 of the two measurement lights emitted by the optical time domain reflectometer 210 are different from the wavelengths ⁇ 31 and ⁇ 32 of the two measurement lights emitted by the optical time domain reflectometer 230 , so that even if the measurement light emitted by one OTDR enters the opposite OTDR, it will be time-transferred by the opposite OTDR due to its wavelength being different from that of the measurement light emitted by the opposite OTDR.
  • Domain reflectometers filter out, rather than being used by optical time domain reflectometers to analyze fiber performance, helping to improve the accuracy of fiber measurements in each direction.
  • the second embodiment above only takes the C+L optical fiber system as an example.
  • the C-band amplifier 511 and the L-band amplifier 512 shown in FIG. amplifier instead, or, when the optical fiber system simultaneously transmits signal lights of three or more bands, the C-band amplifier 511 and the L-band amplifier 512 shown in Figure 3 can also be implemented by three or more amplifiers Instead, the present application will not repeat them one by one.
  • Fig. 7 exemplarily shows a schematic diagram of the architecture of a measurement core division multiplexing system provided by an embodiment of the present application, wherein the optical fiber in the core division multiplexing system may specifically be a multi-core optical fiber, that is, one optical fiber contains multiple core.
  • the core division multiplexing system may include M multi-core optical fibers (ie multi-core optical fiber 1, multi-core optical fiber 2, ..., multi-core optical fiber M, M is a positive integer), Assuming that each of the M multi-core optical fibers contains T cores, the core division multiplexing system may also include T wavelength division multiplexing Modules (WDM module 1, WDM module 2, ..., WDM module T, where T is a positive integer greater than or equal to 2), fan-in and fan-out device 700, optical fiber Amplifier 510, . . . , optical fiber amplifier 5M0 and signal receiver 600.
  • M multi-core optical fibers
  • each of the T wavelength division multiplexing modules can include a signal generator, an optical time domain reflectometer and a wavelength division multiplexer, for each wavelength division multiplexing Module: the signal generator sends signal light to the wavelength division multiplexer, and the optical time domain reflectometer sends two kinds of measurement light whose wavelengths are respectively located on both sides of the wavelength of the signal light to the wavelength division multiplexer. A measurement light and signal light are combined and emitted.
  • the fan-in-fan-out device 700 may include T first ends and a second end, T wavelength division multiplexing modules are respectively connected to the T first ends of the fan-in-fan-out device 700, and the first end of the fan-in-fan-out device 700 The two ends are connected to one end of the multi-core fiber 1 , and the other end of the multi-core fiber 1 is connected to the fiber amplifier 510 .
  • the optical fiber amplifier 510 may also include amplifiers corresponding to multiple bands as described in the second embodiment above, Moreover, a wave division multiplexer may also be provided between the multi-core optical fiber 1 and multiple amplifiers, which will not be repeated in this application.
  • the T wavelength division multiplexing modules can respectively send the optical signals (hereinafter referred to as composite optical signals) obtained by multiplexing to the T first ends of the fan-in and fan-out device 700, by
  • the fan-in and fan-out device 700 couples T composite optical signals to T cores of the multi-core optical fiber 1 respectively, so as to realize core division multiplexing transmission of the T composite optical signals in the same optical fiber.
  • the generated back-return light will return to the second end of the fan-in-fan-out device 700 along the opposite direction of the transmission direction, and the fan-in-fan-out device 700 is transmitted to the wavelength division multiplexer in the wavelength division multiplexing module corresponding to the fiber core through the first end corresponding to the composite optical signal, and then received by the optical time domain reflectometer corresponding to the wavelength division multiplexer.
  • the performance of the fiber core can be determined according to the return light.
  • the optical fiber amplifier 510 can be set to correspond to the wavelength bands of the T signal lights emitted by the T signal generators 1-T, and the signal output by the multi-core optical fiber 1 is transmitted to the optical fiber amplifier 510 (or through the The signal light of different bands is demultiplexed by the wave division multiplexer in the waveband and then sent to the amplifiers corresponding to the respective bands), and the power of the signal light is amplified by the fiber amplifier 510 and then enters the next section of multi-core optical fiber, and the measurement light in it No further transmission is then performed.
  • the optical fiber amplifier By setting the optical fiber amplifier to amplify the power of the weaker signal light transmitted through the previous section of optical fiber, it can compensate the optical power loss caused by the transmission through multiple sections of multi-core optical fiber, realize long-distance transmission of signals, and avoid measurement
  • the measurement light of the previous section of optical fiber interferes with the measurement process of the next section of optical fiber, which helps to improve the accuracy of measuring the next section of optical fiber.
  • the core division multiplexing system may also include a fan-in fan-out device 7M0, which is connected with T cores in the multi-core optical fiber M.
  • a fan-in fan-out device 7M0 which is connected with T cores in the multi-core optical fiber M.
  • the fan-in and fan-out device 7M0 may include an input terminal and T output terminals
  • the fan-in and fan-out device 7M1 may include T first terminals and a second terminal
  • the input terminal of the fan-in and fan-out device 7M0 is connected to an upper section Optical fiber
  • T output ports of the fan-in and fan-out device 7M0 are respectively connected to input ports of T wavelength division multiplexers 3M1-3MT
  • T optical time domain reflectometers 1M1-1MT are respectively connected to T wavelength division multiplexers 3M1-3MT
  • the first communication terminals of 3MT, the second communication terminals of T wavelength division multiplexers 3M1-3MT are respectively connected to T first terminals of fan-in and fan-out devices 7M1
  • the second terminals of fan-in and fan-out devices 7M1 are connected to multi-core
  • One end of the optical fiber M and the other end of the multi-core optical fiber M are connected to the input end of the optical fiber amplifier 5M0, and the output end of the optical fiber amplifier
  • the fan-in and fan-out device 7M0 can respectively send T optical signals transmitted from the T cores in the last section of optical fiber to T wavelength division multiplexers 3M1-3MT, and the T optical signals
  • the time domain reflectometer 1M1-1MT can send two kinds of measurement light with different wavelengths to the corresponding wavelength division multiplexer 3M1-3MT respectively, and the two kinds of measurement light emitted by each optical time domain reflectometer pass through the corresponding wavelength division multiplexer
  • the optical signal transmitted by the device and the corresponding fiber core in the previous section of optical fiber is combined into a composite optical signal and then sent to the fan-in and fan-out device 7M1, and the received T composite optical signals are respectively coupled to at least T cores of the core fiber M, so as to realize core division multiplexing transmission of T composite optical signals in the multi-core fiber M.
  • each composite optical signal when each composite optical signal is transmitted in the corresponding fiber core, the generated back-return light will return to the second end of the fan-in-fan-out device 7M1 along the opposite direction of the transmission direction, and the fan-in-fan-out device 7M1 is transmitted to the wavelength division multiplexer corresponding to the fiber core, and then forwarded by the wavelength division multiplexer to the corresponding optical time domain reflectometer.
  • the return light of the corresponding core in the multi-core optical fiber M can be determined. performance. By setting T optical time domain reflectometers at the left end of the multi-core fiber M in the figure, the performance of each core in the multi-core fiber M measured from left to right in the figure can be obtained.
  • the optical fiber measurement system shown in FIG. 7 can realize unidirectional measurement of one or more fiber cores.
  • the above content is introduced by taking the measurement of T fiber cores at the same time as an example.
  • multiple optical time domain reflectometers corresponding to multiple fiber cores can simultaneously send measurement light Synchronous measurement of the core to improve the efficiency of the measurement, or only one optical time domain reflectometer can be used to send the measurement light to realize the measurement of a fiber core at a time, so as to reduce the interference of different measurements, of course, it can also be measured multiple times , and in each measurement, the measurement light is sent through the corresponding part of the optical time domain reflectometer to realize the measurement of some of the fiber cores, which is not specifically limited.
  • the multi-core optical fiber M when measuring the multi-core optical fiber M and a certain section or sections of multi-core optical fiber before the multi-core optical fiber M at the same time, in order to further avoid the The measurement light used by the optical fiber interferes with the measurement process of the multi-core optical fiber M.
  • each output end of the fan-in fan-out device 7M0 and the corresponding wavelength division multiplexer A wave division multiplexer, through the wave division multiplexer, decodes the signal light and non-signal light (such as measurement light) in the composite optical signal transmitted from the previous section of multi-core optical fiber, and sends the decoded signal light to all
  • the corresponding wavelength division multiplexer discards the decoded non-signal light or sends it to other additional receiving devices.
  • This implementation can ensure that only the signal light transmitted from the previous section of multi-core fiber enters the wavelength division multiplexer, and then is coupled to the multi-core fiber M together with the measurement light of the multi-core fiber M.
  • the optical fiber measurement solution in this application can also realize bidirectional measurement of one or more fiber cores.
  • FIG. With the schematic diagram of the system architecture, as shown in Figure 8, if you want to realize bidirectional measurement of one or more cores in the multi-core fiber 1, you can also set the fan-in and fan-out device 701, and the multi-core fiber 1 T wave division multiplexers 411-41T corresponding to T fiber cores one-to-one, T optical time domain reflectometers 21-2T corresponding to T wave division multiplexers 411-41T one-to-one, and fan-in and fan-out Device 702 .
  • the fan-in and fan-out device 701 includes a first end and T second ends
  • the fan-in and fan-out device 702 includes T input ends and an output end
  • the first end of the fan-in and fan-out device 701 is used to connect multiple The other end of the core fiber 1
  • the T second ends of the fan-in and fan-out device 701 are respectively connected to the first communication ends of the T wave division multiplexers 411-41T
  • the T optical time domain reflectometers 21-2T are connected to the T
  • the output terminals of the T WDM multiplexers 411-41T are respectively connected to the T input terminals of the fan-in-fan-out device 702, and the output of the fan-in fan-out device 702
  • the end is connected to the fiber amplifier 510.
  • T optical time domain reflectometers 1-T in the T wavelength division multiplexing modules respectively send two
  • T optical time domain reflectometers 21-2T can also emit two kinds of reverse measuring light of different wavelengths respectively.
  • the forward measuring lights emitted by the T optical time domain reflectometers 1-T are respectively forwardly coupled into the T cores of the multi-core optical fiber 1 through the fan-in and fan-out devices 700, so that according to the above content, the light from the left can
  • the first target performance curves of the T cores in the multi-core optical fiber 1 are obtained by measuring in the right direction.
  • the signals transmitted to the T cores of the fan-in-fan-out device 701 through the multi-core optical fiber 1 are respectively coupled to the respective corresponding wave division multiplexers 411-41T through the fan-in fan-out device 701, and then passed through the respective wave demultiplexers
  • the multiplexer forwards the signal light therein to the fan-in-fan-out device 702, and the fan-in-fan-out device 702 is respectively coupled to T fiber cores in the next section of optical fiber.
  • the reverse measurement light emitted by the T optical time domain reflectometers 21-2T will be coupled to the T second ends of the fan-in-fan-out device 701 through the corresponding wave division multiplexers 411-41T, and then passed through
  • the fan-in and fan-out devices 701 are reversely coupled to T cores in the multi-core optical fiber 1 respectively, and transmit in the multi-core optical fiber 1 along the direction from right to left as shown.
  • the return lights of the T cores in the multi-core optical fiber 1 return to the fan-in-fan-out device 701, and are respectively coupled to the corresponding T wave-division multiplexers 411-41T through the fan-in-fan-out device 701, and then forwarded to the corresponding T optical time domain reflectometers 21-2T, and each optical time domain reflectometer determines the T in the multi-core optical fiber 1 measured from right to left according to the return light of the corresponding optical fiber.
  • the second target performance curve of a fiber core is subsequently used to determine the T in the multi-core optical fiber 1 measured from right to left according to the return light of the corresponding optical fiber.
  • the above content is only introduced by taking the simultaneous bidirectional measurement of T cores in the multi-core optical fiber 1 as an example.
  • the forward measurement can only be sent through the optical time domain reflectometer in the wavelength division multiplexing module corresponding to the core Light, and the reverse measurement light is sent through the optical time domain reflectometer corresponding to the fiber core, while the optical time domain reflectometer in the wavelength division multiplexing module corresponding to the other fiber core and the reversely configured light
  • a time domain reflectometer may not send measurement light.
  • the wavelengths of the measurement light emitted by the two optical time domain reflectometers located at the two ends of the core are different.
  • the optical time domain reflectometer 1 emits a wavelength
  • the two measuring lights of ⁇ 11 and ⁇ 12 are used to measure a certain fiber core in the multi-core fiber 1 in the forward direction
  • the optical time domain reflectometer 21 emits two measuring lights of wavelengths ⁇ 13 and ⁇ 14 to measure the multi-core fiber in the reverse direction 1, the wavelengths ⁇ 11 , ⁇ 12 , ⁇ 13 and ⁇ 14 are different.
  • the way of bidirectionally measuring each intermediate multi-core fiber in the multi-core fiber 2 to the multi-core fiber M can be realized by referring to the above-mentioned way of bidirectionally measuring the multi-core fiber 1.
  • the two-way measurement of a fiber core can also be arranged in the manner of T forward optical time domain reflectometers 1-T and T reverse optical time domain reflectometers 21-2T as shown in Figure 8, when required T forward optical time domain reflectometers and T reverse optical time domain reflectometers are respectively installed at both ends of the measured intermediate multi-core optical fiber.
  • T forward optical time domain reflectometers and T reverse optical time domain reflectometers are respectively installed at both ends of the measured intermediate multi-core optical fiber.
  • FIG. 9 exemplarily shows a schematic diagram of the architecture of a measurement mode division multiplexing system provided by an embodiment of the present application, wherein the optical fiber in the mode division multiplexing system can specifically be a few-mode optical fiber, that is, a single optical fiber can simultaneously transmit different pattern of light signals.
  • the mode division multiplexing system may include N few-mode fibers (ie few-mode fibers 1, few-mode fibers 2, ..., few-mode fibers N, N is a positive integer), It can also include R wavelength division multiplexing modules (ie wavelength division multiplexing module 1, wavelength division multiplexing module 2, ..., wavelength division multiplexing module R, R is a positive integer greater than or equal to 2) , mode multiplexer 800, fiber amplifier 510, . . . , fiber amplifier 5N0 and signal receiver 600.
  • R wavelength division multiplexing modules ie wavelength division multiplexing module 1, wavelength division multiplexing module 2, ..., wavelength division multiplexing module R, R is a positive integer greater than or equal to 2
  • mode multiplexer 800 ie wavelength division multiplexing module 1, wavelength division multiplexing module 2, ..., wavelength division multiplexing module R, R is a positive integer greater than or equal to 2
  • mode multiplexer 800 ie wavelength division multiplexing module 1, wavelength division multiplexing module 2, ..., wavelength division
  • the mode multiplexer 800 may include R first ends and a second end, and the R wavelength division multiplexing modules are respectively connected to the R first ends of the mode multiplexer 800, and the second end of the mode multiplexer 800 is connected to One end of the few-mode fiber 1 and the other end of the few-mode fiber 1 are connected to a fiber amplifier 510 .
  • the connection relationship and implementation process of the optical fiber amplifier 510, the optical fiber amplifier 5N0, and the signal receiver 600 in this solution are consistent with those in the third embodiment above, and this application will not repeat the introduction one by one.
  • the R wavelength division multiplexing modules can respectively send the composite optical signals of the fundamental modes obtained by multiplexing to the mode multiplexer 800, and the mode multiplexer 800 performs a After the composite optical signal generates one mode, the composite optical signals of R modes are coupled to at least one mode fiber 1, so as to realize mode multiplexing transmission of composite optical signals of different modes in the few-mode fiber 1.
  • each optical time domain reflectometer can determine the performance loss of the few-mode fiber 1 when transmitting the converted mode of the composite optical signal of the fundamental mode sent by the wavelength division multiplexing module. This scheme can measure the performance corresponding to each mode from left to right along the diagram, and realize unidirectional measurement of each mode in the few-mode fiber 1 .
  • the optical fiber amplifier 510 can be set to correspond to the wavelength bands of the R signal lights emitted by the R signal generators 1-R, and the optical signals of different modes output by the few-mode optical fiber 1 are transmitted to the optical fiber amplifier 510 (or through
  • the wave division multiplexer in the second embodiment demultiplexes the signal light into different bands and then sends them to the amplifiers corresponding to each band), and then the signal light is amplified through the optical fiber amplifier 510 and then enters the next few-mode optical fiber , while the measuring light in it is not transmitted further.
  • the fiber amplifier By setting the fiber amplifier to amplify the power of the weaker signal light transmitted through the last few-mode fiber, it can compensate the optical power loss caused by the transmission through multiple few-mode fibers, and realize long-distance transmission of the signal. Preventing the measurement light from entering the next few-mode fiber and causing the measurement light of the previous few-mode fiber to interfere with the measurement process of the next few-mode fiber is conducive to improving the accuracy of measuring the next few-mode fiber.
  • the mode division multiplexing system can also include a mode multiplexer 8N0, which corresponds to the R modes in the few-mode fiber N one-to-one R wavelength division multiplexers 3N1-3NR, R optical time domain reflectors 1N1-1NR and mode multiplexer 8N1 corresponding to the R wavelength division multiplexers 3N1-3NR one-to-one.
  • a mode multiplexer 8N0 which corresponds to the R modes in the few-mode fiber N one-to-one R wavelength division multiplexers 3N1-3NR, R optical time domain reflectors 1N1-1NR and mode multiplexer 8N1 corresponding to the R wavelength division multiplexers 3N1-3NR one-to-one.
  • the mode multiplexer 8N0 may include an input port and R output ports
  • the mode multiplexer 8N1 may include R first ports and a second end
  • the input port of the mode multiplexer 8N0 is connected to a section of few-mode optical fiber
  • the R output terminals of the mode multiplexer 8N0 are respectively connected to the input terminals of the R wavelength division multiplexers 3N1-3NR
  • the R optical time domain reflectors 1N1-1NR are respectively connected to the R wavelength division multiplexers 3N1-3NR
  • the first communication end, the second communication end of the R wavelength division multiplexers 3N1-3NR are respectively connected to the R first ends of the mode multiplexer 8N1, and the second end of the mode multiplexer 8N1 is connected to one end of the few-mode fiber N
  • the other end of the few-mode fiber N is connected to the input end of the fiber amplifier 5N0
  • the output end of the fiber amplifier 5N0 is connected to the signal receiver 600 .
  • the mode multiplexer 8N0 can perform demode processing on the optical signals of R modes transmitted by the previous few-mode fiber, and obtain R fundamental mode optical signals and send them to the R waves respectively.
  • Division multiplexers 3N1-3NR, and R optical time domain reflectometers 1N1-1NR can respectively send measurement lights of two different wavelengths to the corresponding R wavelength division multiplexers 3N1-3NR, and each optical time domain reflectometer
  • the two kinds of measurement light emitted by the instrument are multiplexed by the corresponding wavelength division multiplexer and the optical signal corresponding to the fundamental mode transmitted from the previous section of optical fiber to form a composite optical signal, and then sent to the mode multiplexer 8N1, and the mode multiplexer 8N1
  • the composite optical signals of R modes corresponding to the composite optical signals of R fundamental modes are generated and then coupled to the at least mode fiber N, so as to realize the mode division multiplexing transmission of the composite optical signals of R modes in the few-mode fiber N.
  • the return light of R modes is demoderated, the return light of R basic modes is obtained and sent to the corresponding R wavelength division multiplexers 3N1-3NR respectively, and then transmitted to Each mode corresponds to an OTDR.
  • the performance of the corresponding mode in the few-mode fiber N can be determined according to the return light.
  • the optical fiber measurement system shown in FIG. 9 can realize unidirectional measurement of one or more modes.
  • the above content is introduced by taking the measurement of R modes at the same time as an example.
  • multiple optical time domain reflectometers corresponding to multiple modes can send measurement light at the same time to realize the synchronization of multiple modes measurement, in order to improve the efficiency of the measurement, it is also possible to realize the measurement of a mode by sending the measurement light through only one optical time domain reflector at a time, so as to reduce the interference of different measurements, of course, it can also be multiple measurements, and in each In the second measurement, the measurement light is sent by the corresponding part of the optical time domain reflectometer to realize the measurement of some of the modes, which is not specifically limited.
  • a The wave-division multiplexer after deciphering the signal light and non-signal light (such as measurement light) in the composite signal transmitted by the last few-mode fiber through the wave-division multiplexer, sends the decomposed signal light to the corresponding The wavelength division multiplexer discards the decoded non-signal light or sends it to other additional receiving devices.
  • This implementation can ensure that only the signal light transmitted by the previous few-mode fiber enters the wavelength division multiplexer, and then converts the mode together with the measurement light of the few-mode fiber N and then couples at least the mode fiber N, so that even the few-mode fiber N
  • the measurement light of the same wavelength as that of other few-mode fibers located in front of the few-mode fiber N will not interfere with the measurement process of the few-mode fiber N, thereby effectively improving the measurement accuracy of the few-mode fiber N.
  • the optical fiber measurement solution in this application can also realize bidirectional measurement of one or more modes.
  • Figure 10 exemplarily shows another measurement mode division multiplexing provided by the embodiment of this application
  • the schematic diagram of the system architecture as shown in Figure 10, if you want to realize the two-way measurement of one or more modes in the few-mode fiber 1, you can also set the mode multiplexer 801 and the R modes in the few-mode fiber 1
  • R wave division multiplexers 411 - 41R, R optical time domain reflectometers 21 - 2R corresponding one to one to the R wave division multiplexers 411 - 41R, and the mode multiplexer 802 corresponding R wave division multiplexers 411 - 41R, R optical time domain reflectometers 21 - 2R corresponding one to one to the R wave division multiplexers 411 - 41R, and the mode multiplexer 802 .
  • the mode multiplexer 801 includes a first end and R second ends
  • the mode multiplexer 802 includes R input ports and an output end
  • the first end of the mode multiplexer 801 is used to connect the few-mode fiber 1 at the other end of the mode multiplexer 801
  • the R second ends of the mode multiplexer 801 are respectively connected to the first communication ends of the R wavelength division multiplexers 411-41R
  • the R optical time domain reflectors 21-2R are respectively connected to the R wavelength division multiplexers 411-41R.
  • the second communication terminals of the multipliers 411-41R, the output terminals of the R wavelength division multiplexers 411-41R are respectively connected to the R input terminals of the mode multiplexer 802, and the output terminals of the mode multiplexer 802 are connected to the optical fiber amplifier 510.
  • the R optical time domain reflectometers 21 - 2R can also emit two kinds of reverse measuring lights of different wavelengths respectively.
  • the forward measurement light emitted by the R optical time domain reflectometers 1-R is converted into R modes by the mode multiplexer 800 and then forwardly coupled into at least the mode fiber 1, so as to follow the above content along the diagram from left to right
  • the first target performance curve of the R modes in the few-mode fiber 1 is obtained by measuring to the right.
  • the signal transmitted to the mode multiplexer 801 through the few-mode optical fiber 1 is demoderated by the mode multiplexer 801 and then restored to the fundamental mode signal, and then the signal light of the fundamental mode is processed by the respective corresponding wave division multiplexers. Coupled to the R first ends of the mode multiplexer 802, the signal light of the R modes corresponding to the signal light of the R fundamental mode is generated by the mode multiplexer 802 and sent to the optical fiber amplifier 510 for amplification and transmission to the next section of optical fiber .
  • the reverse measurement light emitted by the R optical time domain reflectometers 21-2R will be coupled to the R second ends of the mode multiplexer 801 through the corresponding wave division multiplexers 411-41R, and then passed through the mode
  • the multiplexer 801 is converted into R modes and then reversely coupled into the at least-mode fiber 1, and transmits in the few-mode fiber 1 along the direction from right to left as shown in the figure.
  • the return light of the R modes of the few-mode fiber 1 is de-mode-processed by the mode multiplexer 801, and then respectively coupled to the corresponding R wave division multiplexers 411-41R, and then forwarded to the corresponding R optical time domain reflectometers 21-2R, and each optical time domain reflectometer determines the R in the few-mode fiber 1 measured from right to left according to the return light of the corresponding mode.
  • the second target performance curve for each mode In this way, by setting two optical time domain reflectometers corresponding to each mode at the two ends of the few-mode fiber 1, bidirectional measurement of each mode in the few-mode fiber 1 can be realized, and each mode in the few-mode fiber 1 can be provided.
  • the loss information of the two directions of the mode at the same position helps to more accurately quantify the loss of each mode, and expand the effective measurement range of each mode, effectively improving the measurement accuracy of each mode in the mode division multiplexing system accuracy.
  • the forward measuring light can be sent only through the optical time domain reflectometer set in the forward direction in a wavelength division multiplexing module, and the forward measuring light can be sent through
  • the OTDR in this mode corresponds to sending the reverse measurement light, while the OTDR and the OTDR in other wavelength division multiplexing modules do not need to send measurement light.
  • the measurement light emitted by the forward-facing optical time domain reflectometer in the wavelength division multiplexing module is sent to the side of the mode multiplexer 800 in the same direction as the signal light, and is converted into the mode to be measured by the mode multiplexer 800
  • the optical time domain reflectometer in the wavelength division multiplexing module can, according to the return light, Determine the first target performance curve of the few-mode fiber 1 transmitting the signal of the mode shown in the measurement from left to right.
  • the reversely set optical time domain reflectometer can send measurement light of two different wavelengths to the corresponding wavelength division multiplexer, and after being coupled to the mode multiplexer 801 through the wavelength division multiplexer, the mode multiplexer 801 is converted into the mode to be measured and coupled to at least the right end of the mode fiber 1 in the figure, and is transmitted in the few-mode fiber 1 along the direction from right to left in the figure, and the measurement light of this mode is in the few-mode fiber 1 During transmission, the return light generated returns to the mode multiplexer 801, is de-moded by the mode multiplexer 801, and then forwarded to the corresponding wave division multiplexer, and then forwarded to the corresponding optical time domain reflectometer, which is transmitted by the optical time domain reflector According to the return light of the same mode corresponding to the two measurement lights, the instrument measures from right to left along the diagram to obtain the second target performance curve of the mode transmitted by the few-mode fiber 1 . Combining the first target performance curve of the mode obtained by the forward measurement and the second target
  • the wavelengths of the measurement light emitted by the two optical time domain reflectometers located at both ends of the few-mode fiber 1 are different.
  • the optical time domain reflectometer R emits Two measuring lights with wavelengths ⁇ R1 and ⁇ R2 are used to measure a certain mode in the few-mode fiber 1 in the forward direction
  • optical time domain reflectometer 2R emits two measuring lights with wavelengths ⁇ R3 and ⁇ R4 to measure the few-mode fiber in the reverse direction 1
  • the wavelengths ⁇ R1 , ⁇ R2 , ⁇ R3 and ⁇ R4 are different.
  • the method of bidirectionally measuring the few-mode fiber 2 and at least each intermediate few-mode fiber in the few-mode fiber N can be realized by referring to the above-mentioned method of bidirectionally measuring the few-mode fiber 1.
  • R forward optical time domain reflectometers 1-R and R reverse optical time domain reflectometers 21-2R as shown in Figure 10.
  • R forward optical time domain reflectometers and R reverse optical time domain reflectometers are respectively installed at both ends of the middle few-mode fiber to be measured.
  • DSP digital signal processing
  • the returned light may include scattered light and reflected light, and may also include other types of returned light, which is not specifically limited.
  • the following takes the measurement of the few-mode fiber N in Figure 9 as an example to further introduce the measurement process under different stimulated scattering effects.
  • two optical time domain reflectometers 1N1 and 1N2 and two wavelength division multiplexers 3N1 and 3N2 are provided at the upstream end of the few-mode fiber N:
  • FIG. 11 exemplarily shows a schematic diagram of signal flow in different modes provided by the embodiment of the present application.
  • the optical time domain reflectometer 1N1 can send wavelengths to the wavelength division multiplexer 3N1
  • the measurement light of ⁇ N1 and the measurement light of wavelength ⁇ N2 , and ⁇ N1 and ⁇ N2 are respectively located on both sides of the wavelength ⁇ 01 of the signal light sent by the last few-mode fiber, and the measurement light of wavelength ⁇ N1 has a wavelength of
  • the measuring light of ⁇ N2 and the signal light of wavelength ⁇ 01 are combined by the wavelength division multiplexer 3N1 and then coupled to the mode multiplexer 8N1;
  • the optical time domain reflectometer 1N2 can send the signal light with the wavelength of ⁇ N3 to the wavelength division multiplexer 3N2
  • the measurement light of wavelength ⁇ N4 and the measurement light of wavelength ⁇ N4, and ⁇ N3 and ⁇ N4 are respectively located on both sides of the wavelength ⁇ 02 of the signal light sent by the last few
  • the mode multiplexer 8N1 can generate a mode LP1 corresponding to the measurement light with a wavelength of ⁇ N1 , the measurement light with a wavelength of ⁇ N2 and the signal light with a wavelength of ⁇ 01 , and obtain the measurement optical signal LP1 ⁇ N1 , the measurement optical signal LP1 ⁇ N2 and the signal The optical signal LP1 ⁇ 01 , and another mode LP2 corresponding to the measurement light with a wavelength of ⁇ N3 , the measurement light with a wavelength of ⁇ N4 , and the signal light with a wavelength of ⁇ 02 , to obtain the measurement optical signal LP2 ⁇ N3 , the measurement optical signal LP2 ⁇ N4 and The signal optical signal LP1 ⁇ 02 , and further couples the four measurement optical signals and the two signal optical signals in the two modes together to at least the mode fiber N. further:
  • the mode multiplexer 8N1 performs demode processing on the return optical signals LP1 ⁇ N1 and LP1 ⁇ N2 to obtain corresponding return optical signals, And return to the optical time domain reflectometer 1N1 through the wavelength division multiplexer 3N1, the mode multiplexer 8N1 performs demode processing on the return optical signal LP2 ⁇ N3 and LP2 ⁇ N4 to obtain the corresponding return optical signal, and passes through the wavelength division multiplexer 3N2 returns to OTDR 1N2.
  • the optical time domain reflectometer 1N1 can filter out the returned optical signal consistent with the wavelength ⁇ N1 and ⁇ N2 of the measured optical signal from the returned optical signal, and determine the first Rayleigh scattering performance loss of the mode LP1 according to the returned optical signal of the wavelength ⁇ N1
  • the second Rayleigh scattering performance loss curve of mode LP1 is determined according to the return optical signal of wavelength ⁇ N2 , and the two Rayleigh scattering performance loss curves are weighted to obtain the target Rayleigh scattering performance loss curve corresponding to mode LP1.
  • the optical time domain reflectometer 1N2 can filter out the returned optical signal consistent with the wavelength ⁇ N3 and ⁇ N4 of the measured optical signal from the returned optical signal, and determine the first Rayleigh scattering performance loss of the mode LP2 according to the returned optical signal of the wavelength ⁇ N3 curve, determine the second Rayleigh scattering performance loss curve of mode LP2 according to the return optical signal of wavelength ⁇ N4 , and weight the two Rayleigh scattering performance loss curves to obtain the target Rayleigh scattering performance loss curve corresponding to mode LP2.
  • the return optical signals of different modes on the few-mode fiber N are de-mode-processed by the mode multiplexer 8N1, and return to the optical time domain reflectometer 1N1 and optical After the time domain reflectometer 1N2, on the one hand, the optical time domain reflectometer 1N1 can obtain the returned optical signal consistent with the wavelength ⁇ N1 and ⁇ N2 of the measured optical signal from the returned optical signal, and obtain the target corresponding to the mode P1 in the above-mentioned manner Rayleigh scattering power loss curve, the optical time domain reflectometer 1N2 obtains the returned optical signal consistent with the wavelength ⁇ N3 and ⁇ N4 of the measured optical signal from the returned optical signal, and obtains the target Rayleigh scattering power corresponding to the mode P2 in the above way loss curve, or further obtain the integrated Rayleigh scattering power loss curve of the few-mode fiber N.
  • the optical time domain reflectometer 1N1 it is also possible to use the optical time domain reflectometer 1N1 to obtain the return signal with a certain offset from the wavelength ⁇ N1 and ⁇ N2 of the measurement optical signal from the return light.
  • each wavelength with a certain offset under the mode P1 Determine the Brillouin scattering performance loss curve of each wavelength in mode P1, weight the two Brillouin scattering performance loss curves of wavelengths ⁇ N1 and ⁇ N2 in mode P1, and obtain the target corresponding to mode P1 Brillouin scattering performance loss curve.
  • the optical time domain reflectometer 1N2 obtains the returned optical signal with a certain offset from the wavelength ⁇ N3 and ⁇ N4 of the measured optical signal from the returned light, and determines it according to the returned optical signal of each wavelength with a certain offset in mode P2
  • the Brillouin scattering performance loss curve of each wavelength in mode P2, weighting the two Brillouin scattering performance loss curves of wavelengths ⁇ N3 and ⁇ N4 in mode P2, can obtain the target Brillouin scattering performance corresponding to mode P2 loss curve.
  • the wavelength shift corresponding to Brillouin scattering can be determined through experiments.
  • the experimental process includes: separately exciting different modes of the same wavelength, and measuring the frequency of the Brillouin return light of the wavelength in each mode
  • the offset is to calculate the wavelength offset corresponding to the frequency offset according to the correlation between the frequency and the wavelength.
  • the OTDR 1N1 obtains the returned light, it can determine the response of the returned light caused by Brillouin scattering according to the wavelength shift of the Brillouin returned light under the mode P1 determined by experiments and the wavelength of the measured light. If there is a wavelength, find the returned light corresponding to the expected wavelength from the returned light to construct the Brillouin scattering performance loss curve corresponding to the mode P1.
  • the optical time domain reflectometer 1N2 can determine the response of the returned light caused by Brillouin scattering according to the wavelength shift of the Brillouin returned light under the mode P2 determined by experiments and the wavelength of the measured light. If there is a wavelength, find the returned light corresponding to the expected wavelength from the returned light to construct the Brillouin scattering performance loss curve corresponding to the mode P2.
  • the relatively similar patterns can also be divided into different pattern sets, at least two sets of pattern sets are obtained, and at least two sets of pattern sets are separately measured .
  • the modes to be measured include mode 1, mode 2, mode 3, and mode 4, and mode 1 and mode 2 are relatively similar, and mode 3 and mode 4 are relatively similar, then mode 1 and mode 3 can be divided into the first group mode set, mode 2 and mode 4 are divided into the second group of mode sets (or, mode 1 and mode 4 can also be divided into the first group of mode sets, and mode 2 and mode 3 are divided into the second group of mode sets),
  • First measure the two modes in the first group of mode sets to obtain the performance curve corresponding to mode 1 and the measurement performance curve corresponding to mode 3, and then measure the two modes in the second group of mode sets to obtain mode 2
  • using a pattern multiplexer to generate different patterns is only an optional implementation manner, and the present application does not limit that the pattern multiplexer must be used to generate different patterns.
  • different modes can also be excited by means of offset.
  • the above-mentioned embodiments of the present application only use single-wavelength measurement light as an example for introduction, but the measurement scheme can also be applied to multi-wavelength measurement light, and the relevant execution process can directly refer to the above content, which will not be repeated in this application.
  • the present application also provides an optical time domain reflectometer, the optical time domain reflectometer is connected to the first end of the wavelength division multiplexer, the second end of the wavelength division multiplexer is connected to the signal generator, and the wavelength division multiplexer
  • the optical time domain reflectometer can be used to perform the steps performed by any one of the optical time domain reflectometers in Embodiment 1 to Embodiment 4 above.
  • the present application also provides an optical fiber measurement device, including any optical time domain reflectometer and wavelength division multiplexer introduced in the above content.
  • the present application provides a chip, which may include a processor and an interface, and the processor is used to read instructions through the interface to perform the steps performed by any optical time domain reflectometer in the first to fourth embodiments above.
  • the present application provides a computer-readable storage medium, in which a computer program is stored.
  • the optical time domain reflectometer as described in any one of the above-mentioned embodiments 1 to 4 can be implemented. steps to execute.
  • the present application provides a computer program product, which, when running on a processor, implements the steps performed by any one of the optical time domain reflectometers in Embodiment 1 to Embodiment 4 above.

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Abstract

一种光纤测量系统，可用于对光通信领域中的一根或多根光纤进行测量。该光纤测量系统包括光时域反射仪、波分复用器和信号发生器，信号发生器向波分复用器发送信号光，光时域反射仪向波分复用器发送波长分别位于信号光波长两侧的两个测量光，波分复用器合波两个测量光和信号光后发送至光纤，以及将光纤返回的光发送至光时域反射仪，以便光时域反射仪根据返回的光确定光纤的性能。通过同向传输位于信号光波长两侧的两个测量光，使得波长短的测量光的功率能向信号光一侧转移，信号光的功率又能向波长长的测量光一侧转移，有效抵消两个测量光与信号光在测量过程中的功率转移，在不影响信号光的正常业务传输的同时，提高光纤测量的准确性。

Description

一种光纤测量系统
相关申请的交叉引用
本申请要求在2021年05月13日提交中国专利局、申请号为202110522805.2、申请名称为“一种光纤测量系统”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及光通信技术领域，尤其涉及一种光纤测量系统。
背景技术
光通信领域中，光纤的传输性能越好，光纤对所传输信号光的影响也就越小，有助于信号光近乎无损地传输至接收端。因此，如何准确测量光纤的传输性能，对于确保高质量地传输信号光具有至关重要的作用。
现阶段，测量光纤的常规做法是：从光纤的一端向光纤内发送测量光，采集测量光在光纤中传播时所产生的后向返回光，利用后向返回光来获取光纤中信号衰减的信息。然而，不同波长的光在光纤中传输时会产生受激拉曼散射效应，具体表现为短波长光的功率会向长波长光的功率转移，因此，无论测量光的波长比信号光的波长长还是短，这种测量方式都会由于发生功率的转移而使得测量光的传输受到信号光的影响，导致最终采集到的后向返回光并不准确，不利于提高测量结果的准确性。
综上所述，目前暨需一种光纤测量系统，用以提高光纤测量的准确性。
发明内容
本申请提供一种光纤测量系统，用以提高光纤测量的准确性。
本申请提供一种光纤测量系统，包括信号发生器、第一光时域反射仪和波分复用器，信号发生器用于向波分复用器发送信号光，第一光时域反射仪用于向波分复用器发送波长分别位于信号光的波长两侧的第一测量光和第二测量光，波分复用器用于对第一测量光、第二测量光和信号光进行合波处理后发送至光纤，以及将光纤中返回的光发送至第一光时域反射仪，第一光时域反射仪还用于根据返回的光确定光纤的性能。在上述设计中，通过同向传输位于信号光的波长两侧的两个测量光，使得波长短的测量光的功率能向信号光一侧转移，而信号光的功率又能向波长长的测量光一侧转移，因此，利用这两个测量光的返回光综合确定光纤的性能，能在不影响信号光的正常业务传输的同时，使测量结果中的两个测量光的功率转移相互抵消，有效消除各种受激散射效应对测量过程的干扰，提高测量结果的准确性。
在一种可能的设计中，第一光时域反射仪还可以分多次向光纤中发送不同的第一测量光和第二测量光，并根据每次测量返回的光确定光纤在每次测量中的性能，综合光纤在多次测量中的性能，确定光纤的真实性能，例如将多次测量得到性能的平均值作为光纤的真实性能。该设计能通过多次测量来避免仅通过一次测量确定性能所存在的偶然误差，有助于进一步提高测量结果的准确性。
在一种可能的设计中，信号光可以为单波长信号光，也可以为多波长信号光。在信号光为单波长信号光的情况下，第一测量光和第二测量光的波长分别位于信号光的波长两侧，可以是指：第一测量光的波长大于单波长信号光的波长，第二测量光的波长小于单波长信号光的波长。在信号光为多波长信号光的情况下，第一测量光和第二测量光的波长分别位于信号光的波长两侧，可以是指：第一测量光的波长大于多波长信号光的最大波长，第二测量光的波长小于多波长信号光的最小波长。在该设计中，通过设置一个测量光的波长大于信号光的波长(即单波长或最大波长)、另一个测量光的波长小于信号光的波长(即单波长或最小波长)，还能尽量使信号光向长波长测量光的功率转移和短波长测量光向信号光的波长转移相互抵消，有助于降低测量过程对正常业务传输的影响。
在一种可能的设计中，第一测量光的波长与最大波长的波长差、以及最小波长与第二测量光的波长的波长差均可以位于预设的拉曼增益范围内，其中，预设的拉曼增益范围是使两个不同波长的光信号产生明显受激拉曼散射效应的最大波长差。该设计能确保第一测量光和第二测量光都与信号光发生功率转移，有效提高抵消测量结果中功率转移的可能性。
在一种可能的设计中，第一光时域反射仪可以包括分波器和处理器，分波器用于将返回的光分波为第一测量光对应的第一返回光和第二测量光对应的第二返回光，并将第一返回光和第二返回光发送至处理器，处理器用于根据第一返回光和第二返回光确定光纤的性能。该设计能通过分波器准确将第一测量光和第二测量光各自对应的返回光分开，从而有助于处理器按照每种测量光对应的返回光确定每种测量光的性能，以便综合确定光纤的整体性能。
在一种可能的设计中，第一测量光的波长与信号光的中心波长的波长差和信号光的中心波长与所述第二测量光的波长的波长差相同。在该设计中，通过设置两个测量光与信号光具有相同的波长间隔，能尽量让波长短的测量光转移出去的功率等同于转移进波长长的测量光的功率，如此，直接加和两个测量光所对应的性能曲线，即可大概率抵消两个测量光的功率转移量，该计算方式较为简单，便于实现，有助于提高测量效率。
在一种可能的设计中，性能曲线具体可以是功率衰减曲线。由于光的传播速度是固定的，因此，第一光时域反射仪在发出测量光之后，在不同时刻接收到的返回光的功率也即代表了光纤中不同位置处的损耗的功率，通过统计光纤各个位置处的损耗功率，能获得功率衰减曲线，以准确表征光纤在每个位置处的传输衰减性能。
在一种可能的设计中，处理器具体用于：根据第一返回光获得光纤的第一性能曲线，根据第二返回光获得光纤的第二性能曲线，加权第一性能曲线和第二性能曲线，获得光纤的目标性能曲线。在该设计中，通过同向传输波长分别位于信号光的波长两侧的两个测量光，能使第一光时域反射仪通过加权的方式确定光纤的性能，相比于在两端输入不同频率的测量光来双向测量性能的方式来说，加权的计算方式更为简单，便于实现，有助于提高测量效率。
在一种可能的设计中，第一性能曲线对应的权重和第二性能曲线对应的权重的比值与信号光的频率与第一测量光的频率的频率差和第二测量光的频率与信号光的频率的频率差的比值正相关。其中，信号光的频率可以对应为单波长信号光的频率或多波长信号光的中心频率。该设计参照两个光信号的相对频率与功耗转移之间所具有的正向的线性对应关系，通过按照测量光与信号光之间的频率差来设置对应的权重，能参照第一测量光和第二测量光的真实功率转移情况对等地设置第一性能曲线的权重和第二性能曲线的权重，尽量 让加权后的两条性能曲线对应一正一负且值相同的功率转移，该种权重设置更为合理准确，能较好地修正功率转移对采集到的两个返回光的影响，进一步提高测量结果的准确性。
在一种可能的设计中，信号发生器可以包括K个信号发生单元，K个信号发生单元与K个波段一一对应，K个信号发生单元中的每个信号发生单元用于向波分复用器发送位于所对应波段内的信号光，K为大于或等于2的正整数。其中，K个波段可以包括但不限于：O波段(波长范围为1260nm-1360nm)、E波段(波长范围为1360nm-1460nm)、S波段(波长范围为1460nm-1530nm)、C波段(波长范围为1530nm-1565nm)、L波段(波长范围为1565nm-1625nm)等。如此，该设计能适用于测量混合传输多波段信号的光纤，由于光纤在混合传输多波段信号时的散射效应会愈加明显，因此通过在混合传输多波段信号的光纤中使用能抵消功率转移的方式进行测量，能有效提高测量结果的准确性。
在一种可能的设计中，光纤测量系统还可以包括波分解复用器和连接波分解复用器的第二光时域反射仪，其中，波分复用器和波分解复用器分别位于光纤的两端。在实施中，第二光时域反射仪用于向波分解复用器发送波长分别位于信号光的波长两侧的第三测量光和第四测量光，波分解复用器用于将第三测量光和第四测量光发送至光纤，以及将光纤返回的光发送至第二光时域反射仪，第二光时域反射仪还用于根据返回的光确定光纤在另一方向的性能。在该设计中，通过在同一段光纤的两端分别设置两个光时域反射仪，还能从两个方向对光纤进行测量，通过获得光纤中每个位置处在两个方向上的损耗信息，有助于准确定位光纤的问题点。
在一种可能的设计中，第一测量光、第二测量光、第三测量光和第四测量光的波长互不相同。如此，通过在光纤的两侧设置不同波长的测量光以单独执行测量，还能使对侧发送的测量光不影响本侧光时域反射仪所接收到的返回的光，降低两个方向测量的相互干扰，有效提高每个方向的测量准确度。
在一种可能的设计中，第一光时域反射仪所测量的光纤可以有多种情况，例如：
第一光时域反射仪测量第一段光纤的情况下，光纤可以直接连接信号发生器，第一光时域反射仪利用信号发生器发出的信号光和位于该信号光的波长两侧的两个测量光，实现对第一段光纤的准确测量。
第一光时域反射仪测量非第一段光纤的情况下，光纤测量系统中还可以包括光纤放大器，光纤放大器的输入端连接上一段光纤的输出端(上一段光纤的输入端可以直接连接信号发生器，或通过其它光纤连接信号发生器)，光纤放大器的输出端连接波分复用器，光纤放大器用于对上一段光纤传输过来的信号光进行功率放大后发送给波分复用器。如此，通过设置光纤放大器对经由多段光纤传输过来的较弱的信号光进行功率放大，能补偿经由多段光纤传输所导致的光功率损耗，实现信号的长距离传输。
在一种可能的设计中，光纤放大器可以包括至少两个放大器，波分解复用器的输入端连接上一段光纤的输出端，波分解复用器的至少两个输出端分别连接至少两个放大器的输入端，至少两个放大器的输出端分别连接波分复用器。在实施中，波分解复用器用于将上一段光纤传输过来的信号光分波为位于至少两个波段内的光信号，将位于至少两个波段内的光信号分别发送给至少两个放大器，由至少两个放大器对所接收到的波段内的光信号进行功率放大后发送给波分复用器。该设计能更有针对性地对每个波段的信号光进行放大，有助于按照每个波段的真实需求设置放大器的放大系数。
在一种可能的设计中，光纤可以为多芯光纤，第一光时域反射仪和波分复用器的数量 可以为多个，多个波分复用器与多芯光纤中的多个纤芯一一对应，多个波分复用器与多个第一光时域反射仪一一对应。该情况下，光纤测量系统还可以包括用于连接多个波分复用器和多芯光纤的第一扇入扇出器件，第一扇入扇出器件可以分别将波分复用器合波处理后的光发送至与波分复用器对应的纤芯，以及将多个纤芯返回的光发送至多个纤芯各自对应的波分复用器，之后经由波分复用器将接收到的纤芯返回的光发送给对应的第一光时域反射器，由第一光时域反射仪根据该纤芯返回的光，确定多个纤芯中的对应纤芯的性能。该设计能对多芯光纤中的每个纤芯的性能进行一个方向的单向测量。
应理解，多个纤芯的单向测量过程可以是一起进行的，即多个第一光时域反射仪同时发出测量光，由第一扇入扇出器件同时将多个合波后的光分别耦合至多个纤芯；也可以是每次只测量一个纤芯，即每次只有一个第一光时域反射仪发出测量光，由第一扇入扇出器件将一个合波后的光耦合至一个纤芯；还可以是分多次测量完成，且每次测量其中的部分纤芯，具体不作限定。
在一种可能的设计中，光纤测量系统中还可以包括波分解复用器和第二光时域反射仪，波分解复用器和第二光时域反射仪的数量可以为多个，多个波分解复用器与多芯光纤中的多个纤芯一一对应，多个第二光时域反射仪与多个波分解复用器一一对应，该光纤测量系统还可以包括用于连接多个波分解复用器和多芯光纤的第二扇入扇出器件。该情况下，第二光时域反射仪可以向所连接的波分解复用器发送波长位于信号光的波长两侧的两个测量光，由波分解复用器将所连接的第二光时域反射仪发送的两个测量光发送至第二扇入扇出器件，进而由第二扇入扇出器件分别将波分解复用器发送的两个测量光耦合至与波分复用器对应的纤芯，以及将多个纤芯返回的光发送至多个纤芯各自对应的波分解复用器，由波分解复用器将接收到的纤芯返回的光发送给对应的第二光时域反射仪，进而由第二光时域反射仪根据纤芯返回的光，确定多个纤芯中的对应纤芯在另一方向的性能。该设计能从另一方向对多芯光纤中的每个纤芯的性能进行测量。
应理解，多个纤芯的双向测量过程可以是一起进行的，即多个第一光时域反射仪和多个第二光时域反射仪同时发出测量光，由第一扇入扇出器件同时将多个第一光时域反射仪发出的测量光正向耦合至多个纤芯，由第二扇入扇出器件同时将多个第二光时域反射仪发出的测量光反向耦合至多个纤芯，以实现对多个纤芯的同时双向测量；也可以是每次只双向测量一个纤芯，即每次只有待测纤芯对应的第一光时域反射仪和第二光时域反射仪发出测量光，由第一扇入扇出器件将第一光时域反射仪发出的测量光正向耦合至待测纤芯，由第二扇入扇出器件将第二光时域反射仪发出的测量光反向耦合至待测纤芯；还可以是分多次测量完成，且每次双向测量其中的部分纤芯，具体不作限定。
在一种可能的设计中，光纤可以为少模光纤，第一光时域反射仪和波分复用器的数量可以为多个，多个波分复用器与少模光纤中的多个模式一一对应，多个波分复用器与多个第一光时域反射仪一一对应。该情况下，光纤测量系统还可以包括用于连接多个波分复用器和少模光纤的第一模式复用器，第一模式复用器可以将多个波分复用器合波处理后的光转换为不同模式后发送至少模光纤，以及对少模光纤返回的不同模式的光进行去模式处理后，发送至各自对应的波分复用器，进而由多个波分复用器返回给各自对应的第一光时域反射仪，每个第一光时域反射仪根据去模式后的返回的光，确定少模光纤中对应的模式的性能。该设计能对少模光纤中的每个模式的性能进行一个方向的单向测量。
在上述设计中，多个波分复用器可以分别向模式复用器发出各自对应的基模下的合波 光，第一模式复用器可以将每个波分复用器发出的合波光转化为一种高阶模式，且各个波分复用器所被转化的各个高阶模式弱耦合(弱耦合是指相互影响比较弱，可以忽略，或可以由光时域反射仪进行消除)。相对应的，在少模光纤返回各个高阶模式下的光后，第一模式复用器可以对各个高阶模式下的光进行去模式处理，获得各个波分复用器各自对应的基模下的返回光并发送给各个波分复用器。如此，每个波分复用器根据自己接收到的所对应的基模下的返回光，可以确定该基模也即是该基模对应的被转化的高阶模式的性能。
应理解，多个模式的单向测量过程可以是一起进行的，即多个第一光时域反射仪同时发出测量光，由第一模式复用器同时转换多个合波处理后的光得到对应的各种模式后耦合进光纤；也可以是每次只测量一个模式，即每次只有一个第一光时域反射仪发出测量光，由第一模式复用器只转换一个合波处理后的光得到一种模式后耦合进光纤；还可以是分多次测量完成，且每次测量其中的部分模式，具体不作限定。
在一种可能的设计中，光纤测量系统还可以包括波分解复用器和第二光时域反射仪，波分解复用器和第二光时域反射仪的数量可以为多个，多个波分解复用器与少模光纤中的多个模式一一对应，多个第二光时域反射仪与多个波分解复用器一一对应，该光纤测量系统还可以包括用于连接多个波分解复用器和少模光纤的第二模式复用器。该情况下，第二光时域反射仪可以向所连接的波分解复用器发送波长位于信号光的波长两侧的两个测量光，由波分解复用器将所连接的第二光时域反射仪发送的两个测量光发送至第二模式复用器后，通过第二模式复用器将多个波分解复用器发送的两个测量光转换为不同模式后发送至少模光纤，以及对少模光纤返回的不同模式的光进行去模式处理后，发送至各自对应的波分解复用器，进而由波分解复用器将接收到的模式对应的去模式处理后的返回的光发送给对应的第二光时域反射仪，由第二光时域反射仪根据去模式处理后的返回的光，确定少模光纤中对应的模式在另一方向的性能。该设计能从另一方向对少模光纤中的每个模式的性能进行测量。
应理解，多个模式的双向测量过程可以是一起进行的，即多个第一光时域反射仪和多个第二光时域反射仪同时发出测量光，由第一模式复用器生成多个第一光时域反射仪发出的测量光各自对应的模式后同时正向耦合至少模光纤，由第二模式复用器生成多个第二光时域反射仪发出的测量光各自对应的模式后同时反向耦合至少模纤芯，以实现对少模光纤中的多个模式的同时双向测量；也可以是每次只双向测量一个模式，即每次只有待测模式对应的第一光时域反射仪和第二光时域反射仪发出测量光，由第一模式复用器将第一光时域反射仪发出的测量光转化为待测模式后正向耦合至待测纤芯，由第二模式复用器将第二光时域反射仪发出的测量光转化为待测模式后反向耦合至待测纤芯；还可以是分多次测量完成，且每次双向测量其中的部分模式，具体不作限定。
在一种可能的设计中，返回的光中可以包含测量光在光纤中传输时的瑞利散射光或布里渊散射光。第一光时域反射仪还可以通过控制输出测量光的功率强度来改变散射的类型，例如通过设置测量光的功率小于7dBm，使得光纤中发生瑞利散射而不发生布里渊散射，通过设置测量光的功率大于7dBm，使得光纤中同时发生瑞利散射和布里渊散射。在该设计中，通过调整测量光的强度改变光纤中发生的散射类型，还能根据实际需要测量不同散射类型下的光纤性能，提高光纤测量的适用范围。
附图说明
图1示例性示出本申请实施例适用的一种光通信系统的架构示意图；
图2示例性示出本申请实施例提供的一种光纤测量系统的架构示意图；
图3示例性示出本申请实施例提供的一种功率转移和相对频率的对应关系图；
图4示例性示出本申请实施例提供的一种光纤的单向功率衰减变化曲线的示意图；
图5示例性示出本申请实施例提供的一种测量C+L波分复用系统的架构示意图；
图6示例性示出本申请实施例提供的一种光纤的双向功率衰减变化曲线的示意图；
图7示例性示出本申请实施例提供的一种测量芯分复用系统的架构示意图；
图8示例性示出本申请实施例提供的另一种测量芯分复用系统的架构示意图；
图9示例性示出本申请实施例提供的一种测量模分复用系统的架构示意图；
图10示例性示出本申请实施例提供的一种测量模分复用系统的架构示意图；
图11示例性示出本申请实施例提供的一种不同模式下的信号流转示意图。
具体实施方式
需要说明的是，本申请实施例中的光纤测量方案可以应用于光通信系统，光通信系统是一种以光为载波，利用纯度较高的玻璃拉制成极细的光导纤维作为传输媒介，通过光电变换，以实现用光来传输信息的通信系统。常见的光通信系统包括但不限于：在按照波长划分时，可以包括短波长光通信系统(工作波长为0.8μm-0.9μm范围内)、长波长光通信系统(工作波长为1.0μm-1.6μm范围内)、以及超长光通信系统(工作波长大于1.6μm)；在按照光纤的模式划分时，可以包括单模光通信系统(只能传输一种模式的光信号)、以及少模光通信系统(可传输多种模式的光信号)；在按照应用范围划分时，可以包括公用光通信系统(通常指应用于电信运营商侧的光通信系统)、以及专用光通信系统(通常指应用于电信运营商以外的单位的光通信系统，如应用于交通领域、电力领域的光通信系统等)。
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行描述。应理解，下文所描述的实施例仅仅是本申请的一部分实施例，而不是全部的实施例。
图1为本申请实施例适用的一种可能的光通信系统的架构示意图，如图1所示的系统架构中包括电发射机、光发射机、至少一根光纤、至少一个光中继器、光接收机、以及电接收机等。在实施中，电发射机或电接收机通常可以为终端设备或交换机，电发射机用于发出脉码调制电信号，该脉码调制电信号送入光发射机后，光发射机可以将脉码调制电信号转换成光脉冲信号后耦合至光纤，以进行传输。其中，光发射机中可以包含能完成电-光转换的半导体光源，诸如半导体激光器或半导体发光二极管等。进一步地，光脉冲信号沿着光纤链路传输至光接收机后，光接收机可以将光脉冲信号转换成电信号，然后通过对电信号进行放大等处理操作以后，使其恢复为原来的脉码调制电信号后送入电接收机。其中，光接收机中可以包含能完成光-电转换的光电检测器，诸如光电二极管等。
此外，由于光脉冲信号在光纤链路中传输时通常还存在一定的损耗，为避免损耗过大而导致光脉冲信号无法传输至光接收端，因此整个光纤链路还可以被分为多段，且在任意两段光纤之间设置光中继器以进行光脉冲信号的中继。其中，光中继器一般可以有两种形式，一种是光-电-光转换形式的中继器，另一种是在光信号上直接放大的光放大器，这两 种形式的光中继器都能提高光脉冲信号的功率，以便于将光脉冲信号传输至更远的距离。示例来说，假设图1中存在20根光纤，每根光纤铺设的距离均为80公里，则该光通信系统能够将光发射机送入的光脉冲信号传输至1600公里处的光接收机。
在光通信系统中，如果某一段光纤出现问题(例如连接故障)，则整个光纤链路上传输的光脉冲信号很可能会在该段光纤上被中断，导致整个光通信系统的通信质量受到影响。因此，在光通信系统中，准确测量光纤链路的传输性能，对于高质量地传输光脉冲信号有着至关重要的作用。有鉴于此，本申请提供一种光纤测量方案，该方案用于在光通信系统中的一根或多根光纤的一端或两端设置光时域反射仪，以实现对一根或多根光纤性能的单向或双向测量，及时发现光通信系统中存在问题的光纤。
在介绍具体的实施方式之前，先示例性介绍下文中出现的部分术语：
(1)光的受激散射：受激拉曼散射和受激布里渊散射。
本申请实施例中，高强度的激光在通过光纤时，和光纤中的物质分子发生强烈的相互作用，使得散射过程具有了受激发射的性质，这种非线性的光学效应称为光的受激散射效应。光的受激散射通常还会表现出阈值特性，也即是如激光器一样，只有在适当的光功率下才会产生。现阶段，光纤中通常会发生如下两种受激散射：
受激拉曼散射，是光纤中的泵浦光与硅原子振动间相互作用的结果，主要表现为短波长光的功率向长波长光的功率一侧转移。受受激拉曼散射的影响，短波长光会发生功率的衰减，导致短波长光的光信噪比(optical signal noise ratio，OSNR)(是指在光有效带宽为0.1nm内，光信号的功率和噪声信号的功率的比值)下降，而长波长光则会发生功率的增强，导致非线性干扰增强。通常情况下，受激拉曼散射的发生门限较小，且与光纤的材质、类型和参数相关，当光纤中传输的泵浦光功率超过该光纤中受激拉曼散射的发生门限时，泵浦光即可与该光纤中的硅原子作用而产生受激拉曼散射。
受激布里渊散射，是光纤中的泵浦光与声子振动间相互作用的结果，主要表现为引起通道间的串扰及信道能量的损失。受激布里渊散射通常会产生泵浦光的频移，即激发出与泵浦光的波长不同的另一波长的散射光，另一波长与原波长的偏移量由光纤中的传播常数和材料常数决定，且还可以通过实验先验得到。受激布里渊散射的发生门限比受激拉曼散射的发生门限要高，对于1550nm的泵浦光来说，当泵浦光的功率达到7-8dBm时，泵浦光即可与光纤中的声子作用而产生受激布里渊散射。
(2)光时域反射仪(optical time-domain reflectometer，OTDR)。
本申请实施例中，光时域反射仪是根据泵浦光的后向散射与菲涅耳反向原理制作而成的，通常利用泵浦光在光纤中传播时产生的后向散射光获得光纤的衰减信息，可用于测量光纤衰减、接头损耗、光纤故障点定位以及了解光纤沿长度的损耗分布情况等。目前，业界主要存在两种光时域反射仪，即只发出一个测量光的光时域反射仪，和同时发出两个测量光的光时域反射仪。本申请主要利用同时发出两个测量光的光时域反射仪来完成光纤的测量，关于该光时域反射仪的具体结构请参照如下实施例一中的描述，此处先不做介绍。
(3)多芯光纤。
本申请实施例中，多芯光纤是指一根光纤中包含多个纤芯的光纤，多芯光纤能通过多个纤芯同时传输光信号，有助于提高光信号的传输效率及传输信号量。
(4)少模光纤(few mode fiber，FMF)。
本申请实施例中，少模光纤是指一根光纤中可以同时传输多个模式的信号流的光纤， 也称为多模光纤。少模光纤属于一种单芯光纤，与普通的单模单芯光纤相比，少模光纤可以拥有更大的模场面积，并能允许在几个独立的空间中并行地传输不同模式的信息流，有助于提高光纤的通信容量。
(5)波分复用(wavelength division multiplexing，WDM)。
本申请实施例中，波分复用是指在发送端将两种或多种不同波长的光载波汇合在一起后耦合到同一根光纤中进行传输的技术，通常在接收端还需要经由波分解复用器将汇合在一起的各种波长的光载波进行分离。密集型波分复用(dense wavelength division multiplexing，DWDM)属于波分复用的一种特殊情况，通常用于将两种或多种不同波段的光载波汇合到同一根光纤中，以便能在频域上传输紧密排列的多个相互正交的光载波，且多个光载波的波长间隔远小于非密集型波分复用的波长间隔。密集型波分复用能在同样的传输窗口中传输更多的光载波，有助于提高带宽的利用率。
(6)中心波长。
波分复用通常采用一定的波长间隔发送多个光载波，每个光载波会占用一个波长宽度，中心波长可以认为是多个光载波中的最小波长和最大波长的平均波长。示例来说，假设采用0.4nm的波长间隔发送波段范围1530nm-1565nm内的光载波，则共可以发送80个光载波，如果80个光载波中的最小波长为1530nm，最大波长为1565nm，则中心波长即为1530nm和1565nm的平均波长，即1547.5nm。
在密集型波分复用中，当同一根光纤中同时传输多个波段的光载波时，光纤中存在的波长信道的数目相比于非密集型波分复用来说会大大增加，这会使得光纤中的信号谱宽和入纤总功率也相应增加，导致多种波段的光载波在传输过重中发生严重的受激拉曼散射。实验证明，密集型波分复用中受激拉曼散射的剧烈程度会随着波段数量的增多而成倍数地增加。在这种情况下，密集型波分复用中传输的光载波的波段越多，光载波在传输过程中受受激拉曼散射的影响也会越大，短波长光载波的功率损耗也就越大，长波长光载波的非线性干扰也就越明显，越不利于光纤的传输性能和传输距离。因此，如何准确测量密集型波分复用中的光纤性能，对于及时发现密集型波分复用中的光纤故障具有至关重要的作用。
有鉴于此，本申请实施例提供一种光纤测量系统，用于同时且同向地向光纤发送信号光和位于信号光的波长两侧的两个测量光，以便在不影响光纤的正常业务的情况下，尽可能地抵消两个测量光与信号光之间产生的功率转移，提高测量结果的准确性。
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述。需要理解的是，在本申请的下列描述中，“多个”可以理解为“至少两个”。“第一”、“第二”等词汇，仅用于区分描述的目的，而不能理解为指示或暗示相对重要性，也不能理解为指示或暗示顺序。且，本申请下列实施例中的“连接”指的是电连接，两个电学元件连接可以是两个电学元件之间的直接或间接连接。例如，A与B连接，既可以是A与B直接连接，也可以是A与B之间通过一个或多个其它电学元件间接连接，如A与B连接，也可以是A与C直接连接，C与B直接连接，A与B之间通过C实现了连接。
需要说明的是，下文中的通信端是指既可以做输入端也可以做输出端的端口，通信端只是一种示例性地名称，在其它方案中也可以具有其它名称，例如还可以称为输入/输出端，具体不作限定。
【实施例一】
图2示例性示出本申请实施例提供的一种光纤测量系统的架构示意图，如图2所示，该系统架构中包括信号发生器100、光时域反射仪200(即第一光时域反射仪)和波分复用器300，该示例中的信号发生器100可以对应为图1中的光发射机。其中，信号发生器100的输出端连接波分复用器300的通信端a 1，光时域反射仪200的通信端c连接波分复用器300的通信端a 2，波分复用器300的通信端a 3连接光纤。在需要测量光纤的性能时：信号发生器100可以向波分复用器300的通信端a 1发出信号光；光时域反射仪200可以向波分复用器300的通信端a 2发出波长为λ 1的第一测量光和波长为λ 2的第二测量光，且λ 1和λ 2分别位于信号光的波长的两侧，例如λ 1大于信号光的波长且λ 2小于信号光的波长，或者λ 1小于信号光的波长且λ 2大于信号光的波长；波分复用器300可以对从通信端a 1接收到的信号光、以及从通信端a 2接收到的第一测量光和第二测量光进行合波处理，并通过通信端a 3将合波后的光发送至光纤，以及，通过通信端a 3接收合波后的光在光纤中传输时返回的光，并通过通信端a 2将返回的光发送至光时域反射仪200；光时域反射仪200还可以根据返回的光确定光纤的性能。
为便于介绍方案，下文中假设第一测量光的波长λ 1大于信号光的波长，第二测量光的波长λ 2小于信号光的波长。
本申请实施例中，信号光可以为单波长信号光，也可以为多波长信号光：
当信号光为单波长(例如1530nm)信号光时，第一测量光的波长λ 1可以为大于1530nm的一个波长，例如1550nm，第二测量光的波长λ 2可以为小于1530nm的一个波长，例如1500nm。如此，当1530nm的信号光、1550nm的测量光和1500nm的测量光同时在光纤中传输时，1500nm的测量光的功率会向1530nm的信号光转移，而1530nm的信号光的功率又会向1550nm的测量光转移，只要1500nm的测量光和1550nm的测量光的波长设置合理(例如设置两个测量光与信号光的波长差相同)，则转移进1530nm的信号光的功率和1530nm的信号光转移出去的功率能大概率地相互抵消，可见，该方式不仅能在正常传输信号光的过程中进行测量，还有助于消除测量过程对信号光的正常业务信号传输的影响。且，虽然1500nm的测量光的功率转移和1550nm的测量光的功率转移都会对返回的光有影响，但这两个测量光的功率转移是相反的，通过叠加这两个测量光返回的光来确定光纤的性能，还能消除测量结果受这两个测量光所产生的功率转移的影响，有助于提高测量结果的准确性。由此可知，该测量方式能在在线测量光纤的同时提高光纤测量的准确性。
当信号光为多波长(例如1530nm和1555nm)信号光时，第一测量光的波长λ 1可以为大于多波长中的最大波长1555nm的一个波长，例如1570nm，第二测量光的波长λ 2可以为小于多波长中的最小波长1530nm的一个波长，例如1500nm。如此，当1530nm的信号光、1555nm的信号光、1570nm的测量光和1500nm的测量光同时在光纤中传输时，1500nm的测量光的功率会向1530nm的信号光转移，而1530nm的信号光的功率又会向1555nm的信号光转移，且1555nm的信号光的功率又会向1570nm的测量光转移，只要1500nm的测量光和1570nm的测量光的波长设置合理，则1500nm的测量光转移进1530nm的信号光的功率和1555nm的信号光转移至1570nm的测量光的功率能相互抵消，有助于在降低测量过程对正常传输这两个信号光的影响的同时，提高测量的准确性。更进一步的，多波长信号光在正常业务传输过程中也会存在功率转移，该测量只是抵消了转移进1530nm的信号光的功率和1555nm的信号光转移出去的功率，而并不影响两个信号光之间产生的 功率转移，也即是说，该测量方式还能准确测量出受到信号光本身的功率转移而影响的测量结果，该测量结果能准确表征真实的传输场景。
本申请实施例中，多波长信号光可以是位于一个波段范围内的，也可以是位于多个波段范围内的。当位于多个波段范围内时，示例性地，继续参照图2所示，信号发生器100可以包括K个信号发生单元(如图2所示意的信号发生单元1，信号发生单元2、……、信号发生单元K，K为大于或等于2的正整数)，K个信号发生单元与K个波段一一对应，K个信号发生单元的输出端可以分别连接波分复用器300的通信端a 1，每个信号发生单元用于向波分复用器300发送位于所对应波段内的信号光。其中，K个波段可以从如下波段中进行选择：O波段(波长范围为1260nm-1360nm)、E波段(波长范围为1360nm-1460nm)、S波段(波长范围为1460nm-1530nm)、C波段(波长范围为1530nm-1565nm)、L波段(波长范围为1565nm-1625nm)等。考虑到不同波段的信号光在传输时会具有不同的损耗，而C波段和L波段对应的传输损耗最小，因此，优选地，K个波段可以是C波段+L波段，但也不排除未来会向C波段+L波段+S波段发展。由此可知，本申请中的光纤测量方案不仅适用于对传输单波长信号的光纤进行测量，还能适用于对传输多波段混合信号的光纤进行测量，光纤在传输多波段混合信号时的受激散射效应会愈加明显，因此通过在传输多波段混合信号的光通信系统中使用能抵消功率转移的方式进行光纤测量，能有效提高测量结果的准确性。
在一种可选地实施方式中，第一测量光的波长λ 1与信号光的最大波长(假设为λ max，对应为上述单波长信号光的单波长、或上述多波长信号光的最大波长、或上述多个波段信号光中位于最大波段内的信号光的最大波长)的波长差λ 1-λ max、以及信号光的最小波长(假设为λ min，对应为上述单波长信号光的单波长、或上述多波长信号光的最小波长、或上述多个波段信号光中位于最小波段内的信号光的最小波长)与第二测量光的波长λ 2的波长差λ min-λ 2，均可以位于预设的拉曼增益范围内。其中，预设的拉曼增益范围是使两个不同波长的光信号产生明显受激拉曼散射效应的最大波长差，通常可以设置为90nm-110nm之间的一个值。例如，当预设的拉曼增益范围设置为100nm时，如果信号光中包含波长为1530nm和1555nm的两种信号光，则第一测量光的波长λ 1可以设置为大于1555nm且不大于1655nm的一个波长，第二测量光λ 2的波长可以设置为大于1430nm且不小于1530nm的一个波长，以确保第一测量光和第二测量光都能与信号光发生功率转移，提高相互抵消功率转移的概率。
在一种可选地实施方式中，当两个测量光与信号光的波长差均位于预设的拉曼增益范围内时，这两个测量光都会和信号光发生功率转移，光时域反射仪200在接收到波分复用器300发送的返回的光之后，还可以从返回的光中分别获取第一测量光对应的第一返回光和第二测量光对应的第二返回光，根据第一返回光和第二返回光确定光纤的性能。进一步可选地，确定光纤的性能可以包括：处理器根据第一返回光获得光纤对应的第一性能曲线，根据第二返回光获得光纤对应的第二性能曲线，然后加权第一性能曲线和第二性能曲线，获得光纤的目标性能曲线。其中，第一性能曲线对应为发生功率转入后的第一测量光，第二性能曲线对应为发生功率转出后的第二测量光，为使获取的目标性能曲线能尽量抵消第一测量光的功率转入和第二测量光的功率转出的影响，还可以按照第一测量光的功率转入和第二测量光的功率转出的相关关系，来设置第一性能曲线对应的权重和第二性能曲线对应的权重的相关关系，例如为功率转入或转出较多的测量光对应的性能曲线设置较大的权 重，为功率转入或转出较少的测量光对应的性能曲线设置较小的权重，以尽量让加权后的两条性能曲线能对应一正一负且值相同的功率转移，通过加权这两条性能曲线，能较好地修正功率转移对采集到的两个返回光的影响，有效提高测量结果的准确性。
进一步地，通常情况下，当两个光信号的波长差位于预设的拉曼增益范围内时，两光信号在同向传输的过程中转移的功率与这两个光信号的相对频率之间具有正相关关系。其中，两个光信号的相对频率是指这两个信号的频率的频率差。例如，图3示例性示出本申请实施例提供的一种功率转移和相对频率的对应关系图，如图3所示，当光信号1和光信号2的相对频率为0时，光信号1和光信号2的波长相同，光信号1和光信号2之间不发生功率转移。当光信号1相对于光信号2的相对频率为正值时，光信号1的频率比光信号2的频率大，光信号1的波长比光信号2的波长小，光信号1会向光信号2转移功率，且光信号1相对于光信号2的相对频率越大，则光信号1的波长相比于光信号2的波长越小，光信号1会向光信号2转移越多的功率。例如参照图3所示，在光信号1相对于光信号2的相对频率为Δf 11时，光信号1向光信号2转移的功率为ΔG 11，在光信号1相对于光信号2的相对频率为Δf 12时，光信号1向光信号2转移的功率为ΔG 12，Δf 11小于Δf 12，对应的ΔG 11也小于ΔG 12。当光信号1相对于光信号2的相对频率为负值时，光信号1的频率比光信号2的频率小，光信号1的波长比光信号2的波长大，光信号2会向光信号1转移功率，且光信号1相对于光信号2的相对频率的值越小，则光信号1的波长相比于光信号2的波长越大，光信号2会向光信号1转移越多的功率。例如参照图3所示，在光信号1相对于光信号2的相对频率为-Δf 21时，光信号2向光信号1转移的功率为ΔG 21，在光信号1相对于光信号2的相对频率为-Δf 22时，光信号2向光信号1转移的功率为ΔG 22，Δf 21小于Δf 22，对应的ΔG 21也小于ΔG 22。由此可知，两个光信号之间转移的功率实际上与这两个光信号的相对频率成正相关关系。
按照上述原理，在根据第一测量光的功率转入和第二测量光的功率转出的相关关系来设置第一性能曲线对应的权重和第二性能曲线对应的权重时，还可以设置第一性能曲线的权重与第二性能曲线的权重的比值，正比于，信号光相对于第一测量光的相对频率和第二测量光相对于信号光的相对频率的比值。其中，信号光相对于第一测量光的相对频率是指信号光的中心频率(对应为上述单波长信号光的单频率、或上述多波长信号光的中心频率，与中心波长相似的，多波长信号光的中心频率对应为多波长信号光中的最小频率和最大频率的平均频率)与第一测量光的频率的频率差，第二测量光相对于信号光的相对频率是指第二测量光的频率与信号光的频率的频率差。如此，当第二测量光相对于信号光的相对频率越大、信号光相对于第一测量光的相对频率越小时，第一性能曲线对应的权重越小，第二性能曲线对应的权重越大，如此，加权后的第一性能曲线能尽量弥补第二测量光的较多功率转移至信号光一侧所导致的信号不足，还能尽量减缓信号光的较多功率转移至第一测量光一侧所导致的信号过量，有助于将第一性能曲线和第二性能曲线都均衡到同一个功率转移值上。由此可知，通过同向传输波长分别位于信号光的波长两侧的两个测量光，能使光时域反射仪通过加权的方式确定光纤的性能，相比于在两端输入不同频率的测量光来双向测量性能的方式来说，加权的计算方式更为简单，也更便于实现，有助于提高测量效率。
示例性地，要想完全抵消两个测量光与信号光之间的功率转移，优选地还可以设置第一性能曲线的权重和第二性能曲线的权重的比值，等于，信号光相对于第一测量光的相对频率和第二测量光相对于信号光的相对频率的比值。如此，通过参照第一测量光和第二测 量光的真实功率转移对等地设置第一性能曲线的权重和第二性能曲线的权重，能准确地将第一性能曲线和第二性能曲线对准到同一功率转移值上，该权重设置较为合理，有助于获得最准确的测量结果。
需要说明的是，上述内容中的“设置第一性能曲线的权重与第二性能曲线的权重的比值，正比于，信号光相对于第一测量光的相对频率和第二测量光相对于信号光的相对频率的比值”，也可以是，设置第一性能曲线的权重与第二性能曲线的权重的比值，正比于，第一测量光相对于信号光的相对波长和信号光相对于第二测量光的相对波长的比值。其中，第一测量光相对于信号光的相对波长是指第一测量光的波长λ 1与信号光的中心波长(对应为上述单波长信号光的单波长、或上述多波长信号光的中心波长)的波长差，信号光相对于第二测量光的相对波长为信号光的中心波长与第二测量光的波长λ 2的波长差。由于第一测量光的波长大于信号光的波长，即第一测量光的频率小于信号光的频率，因此第一测量光的波长减信号光的波长所得到的波长差、和信号光的频率减第一测量光的频率所得到的频率差都是正值，也即是第一测量光相对于信号光的相对波长、以及信号光相对于第一测量光的相对频率均为正值。对应的，由于第二测量光的波长小于信号光的波长，即第二测量光的频率大于信号光的频率，因此信号光的波长减第二测量光的波长所得到的波长差、和第二测量光的频率减信号光的频率所得到的频率差都是正值，也即是信号光相对于第二测量光的相对波长、以及第二测量光相对于信号光的相对频率也均为正值。可知，该方案参照波长或频率的真实情况设置正值的相对波长或相对频率，能便于参照两个正值的比值直接设置第一性能曲线的权重与第二性能曲线的权重。
需要指出的是，在一种更为简化的方式下，也可以直接获得信号光与两个第一测量光的相对频率的绝对值，按照这两个绝对值的比值来设置两条性能曲线的权重，或者直接获得信号光与两个第一测量光的相对波长的绝对值，按照这两个绝对值的比值来设置两条性能曲线的权重。另外，按照该种权重设置方式，当两个测量光和信号光的波长差相同，或两个测量光和信号光的频率差相同时，第一性能曲线和第二性能曲线可以对应同一权重，例如均为0.5。
应理解，在另一种可选地实施方式中，当两个测量光与信号光的中心波长的波长差相同时，波长短的测量光转移出去的功率等同于转移进波长长的测量光的功率，因此，光时域反射仪200在根据第一测量光对应的第一返回光确定第一性能曲线、以及根据第二测量光对应的第二返回光确定第二性能曲线后，还可以直接加和第一性能
曲线和第二性能曲线，获得目标性能曲线。该计算方式较为简单，便于实现，能有效提高测量效率。
本申请实施例中，光时域反射仪可以是能产生两种不同波长的测量光的任意结构的光时域反射仪。例如，参照图2所示出的光时域反射仪200，在一个示例中，光时域反射仪200可以包括第一激光器211、第一脉冲调制器221、第二激光器212、第二脉冲调制器222、合波器230、环形器240、分波器250、第一探测器261、第二探测器262和处理器270。其中，第一激光器211的输出端连接第一脉冲调制器221的输入端，第一脉冲调制器221的输出端连接合波器230的第一输入端，第二激光器212的输出端连接第二脉冲调制器222的输入端，第二脉冲调制器222的输出端连接合波器230的第二输入端，合波器230的输出端连接环形器240的输入端b 1，环形器240的通信端b 2连接光时域反射仪200的通信端c，环形器240的输出端b 3连接分波器250的输入端，分波器250的第一输出端连接第一 探测器261的输入端，分波器250的第二输出端连接第二探测器262的输入端，第一探测器261的输出端连接处理器270的第一输入端，第二探测器262的输出端连接处理器270的第二输入端。
在实施中，第一激光器211可以输出波长为λ 1的直流光，该直流光进入第一脉冲调制器221后被调制成波长为λ 1的脉冲形式的第一测量光(脉冲宽度和传输周期不作限定)，进而被发送给合波器230。第二激光器212可以输出波长为λ 2的直流光，该直流光进入第二脉冲调制器222后被调制成波长为λ 2的脉冲形式的第二测量光(脉冲宽度和传输周期不作限定)，进而也被发送给合波器230。合波器230将波长为λ 1的第一测量光和波长为λ 2的第二测量光合波为双波长的测量光信号后，将双波长的测量光信号发送至环形器240的输入端b 1，经由环形器240的通信端b 2输出给波分复用器300，进而在波分复用器300中与信号发生器100输出的信号光合波后，同时且同向地耦合进光纤。双波长的测量光信号在光纤中传输所产生的返回光沿着输入方向的反方向返回至波分复用器300的通信端a 3，之后通过波分复用器300的通信端a 2输出至环形器240的通信端b 2，经由环形器240的输出端b 3输出给分波器250。分波器250将返回光分波为第一测量光对应的第一返回光和第二测量光对应的第二返回光，将第一返回光发送给第一探测器261，由第一探测器261转换成第一模拟电信号后发送给处理器270，以及，将第二返回光发送给第二探测器262，由第二探测器262转换成第二模拟电信号后发送给处理器270。处理器270对第一模拟电信号进行采样获得离散的第一性能曲线，对第二模拟电信号进行采样获得离散的第二性能曲线，之后按照第一性能曲线对应的权重和第二性能曲线对应的权重对这两条性能曲线进行加权平均，获得目标性能曲线。
本申请实施例中，光纤的性能曲线具体可以是功率衰减变化曲线。图4示例性示出一种光纤的功率衰减变化曲线的示意图，如图4所示，光时域反射仪200在光纤的一端发出测量光后，测量光会沿着光纤从光纤的一端传输至另一端，传输到每个位置时受每个位置的介质材料影响产生返回光并返回至光时域反射仪200，由于光速是固定的，因此光时域反射仪200在不同时刻采集到的反向反射光的功率实际上也即是光纤的不同位置处的功率损耗。按照该原理，光时域反射仪200在发出两个测量光后，都可以实时接收返回的每个测量光对应的返回光，根据每个测量光对应的不同时刻的返回光构建得到一个功率衰减变化曲线，加权两个功率变化曲线后获得如图4所示意的目标功率变化曲线。根据该目标功率变化曲线，能获知光纤中存在问题的位置点，例如图4中光纤上的位置P1处对应的功率突增0.02dB，该突增情况表示位置P1处可能存在光纤芯区的变化，图4中光纤上的点P2处对应的功率突降0.12dB，该突降情况显示位置P2处可能存在有损拼接。
需要说明的是，在上述内容中，测量光对应的返回光可以是与测量光的波长相同的返回光(例如当返回光是由瑞利散射导致时，散射过程并不会影响到测量光的波长，也即是返回光和测量光具有相同波长)，也可以是与测量光的波长存在一定偏差的返回光(例如当返回光是由布里渊散射导致时，散射过程会激发出与测量光的波长不同的新的光载波，也即是返回光和测量光可以具有不同波长)，当然还可以同时包括与测量光的波长相同和与测量光的波长具有一定偏差的两种或两种以上的返回光(同时激发瑞利散射和布里渊散射)。
示例性地，第一激光器211和第二激光器212还可以具备波长可调的功能。在实施中，第一激光器211和第二激光器212还可以连接处理器270，处理器270还可以多次控制第 一激光器211和第二激光器212发出多种波长组合下的直流光，并通过采集每种波长组合下的返回光获得每种波长组合下的目标性能曲线，之后综合多种波长组合下的多个目标性能曲线确定最终的目标性能曲线，例如将多个目标性能曲线的平均性能曲线作为最终的目标性能曲线。如此，通过综合多次测量的测量结果获得最终的测量结果，不仅能使测量结果更有说服力，还能避免仅通过一次测量确定性能所存在的偶然误差，有助于进一步提高测量结果的准确性。
应理解，上述图2所示出的光时域反射仪200只是一种示例，在实施中，还可以对图2所示意的光时域反射仪200进行一些变形以获得新的光时域反射仪。例如，在另一个示例中，还可以在分波器250和第一探测器261、以及分波器250和第二探测器262之间分别设置一个滤波器，先使用滤波器滤除每个链路上传输的测量光对应的返回光以外波长的光后，再将滤波得到的返回光发送至处理器270，以提高处理器270构建性能曲线时所使用的输入信号的纯度。又如，在又一个示例中，还可以在第一脉冲调制器221和合波器230、以及第二脉冲调制器222和合波器230之间分别设置一个偏振开关，先使用偏振开关对每个脉冲调制器调制后的测量光进行纠偏后，再合波纠偏后的各个测量光。再如，在再一个示例中，还可以设置脉冲发生器，脉冲发生器的一端连接第一脉冲调制器221和第二脉冲调制器222，脉冲发生器的另一端连接处理器270，处理器270还能先指示脉冲发生器产生所需的脉冲形式后，经由脉冲发生器将脉冲形式发送给脉冲调制器，以进行测量光的脉冲调制，以及，第一脉冲调制器221或第二脉冲调制器222还可以在完成测量光的脉冲调制后，通过脉冲发生器将调制结果通知给处理器270，以便处理器270和这两个脉冲调制器能维持时间的同步。应理解，凡是能产生两个不同波长的测量光的任意结构的光时域反射仪都在本申请的保护范围内，本申请对此不再一一介绍。
在上述实施例一中，通过同向传输位于信号光的波长两侧的两个测量光，使得波长短的测量光的功率能向信号光一侧转移，而信号光的功率又能向波长长的测量光一侧转移，利用这两个测量光的返回光综合确定光纤的性能，有助于使测量结果中的两个测量光的功率转移相互抵消，有效消除受激散射效应对测量过程的干扰，有助于在不影响信号光的正常传输业务的情况下，提高测量结果的准确性。且，同向传输两个测量光和信号光的方案，还能使光时域反射仪采用加权方式计算出光纤的性能，加权方式计算简单，便于实现，因此还有助于提高光纤测量的效率。
下面基于实施例二至实施例四，进一步介绍实施例一中的光纤测量系统在不同场景下的应用。
【实施例二】
图5示例性示出本申请实施例提供的一种测量C+L波分复用系统的架构示意图，如图5所示，在该示例中，C+L波分复用系统中可以包括至少两根光纤，如光纤1和光纤2，还可以包括信号发生器100、波分复用器310、波分解复用器410、C波段放大器511、L波段放大器512、波分复用器320、波分解复用器420和信号接收器600。该示例中的信号发生器100可以对应为图1中的光发射机，信号接收器600可以对应为图1中的光接收机，而C波段放大器511和L波段放大器512可以设置在图1中的光中继器中。其中，信号发生器100中可以包括C波段信号发生单元110和L波段信号发生单元120，信号接收器600中可以包括C波段信号接收单元610和L波段信号接收单元620。C波段信号发生单元110 的输出端连接波分复用器310的输入端a 11，L波段信号发生单元120的输出端连接波分复用器310的输入端a 12，波分复用器310的通信端a 13连接光纤1的一端；光纤1的另一端连接波分解复用器410的通信端a 21，波分解复用器410的输出端a 22连接C波段放大器511的输入端，波分解复用器410的输出端a 23连接L波段放大器512的输入端，C波段放大器511的输出端连接波分复用器320的输入端a 31，L波段放大器512的输出端连接波分复用器320的输入端a 32，波分复用器320的通信端a 33连接光纤2的一端；光纤2的另一端连接波分解复用器420的输入端a 41，波分解复用器420的输出端a 42连接C波段信号接收单元610的输入端，波分解复用器420的输出端a 43连接L波段信号接收单元620的输入端。
在C+L波分复用系统中，C波段信号发生单元110可以向波分复用器310发送位于1530nm-1565nm波长范围内的C波段信号光，L波段信号发生单元120可以向波分复用器310发送位于1565nm-1625nm波长范围内的L波段信号光，波分复用器310对C波段信号光和L波段信号光进行合波处理，将合波后的信号光耦合进光纤1，进而在光纤1中传输至波分解复用器410。波分解复用器410解耦合波后的信号光，获得其中的C波段信号光并传输给C波段放大器511进行放大，获得其中的L波段信号光并传输给L波段放大器512进行放大。放大后的C波段信号光和放大后的L波段信号光进入波分复用器320，由波分复用器320进行合波处理，并将合波后的信号光耦合进光纤2，进而在光纤2中传输至波分解复用器420。波分解复用器420解耦合波后的信号光，获得其中的C波段信号光并发送给C波段信号接收单元610，获得其中的L波段信号光并发送给L波段信号接收单元620。
本申请实施例可以对C+L波分复用系统中的任意一根光纤或任意多根光纤进行测量：
在测量光纤1时，C+L波分复用系统中还可以包括光时域反射仪210，光时域反射仪210连接波分复用器310的通信端a 14，用于向波分复用器310发送波长为λ 11和λ 12的两种测量光。如此，C波段信号发生单元110发出的C波段信号光、L波段信号发生单元120发出的L波段信号光、以及光时域反射仪210发出的两种波长的测量光会同时且同向地进入波分复用器310，经由波分复用器310合波后耦合进光纤1，而合波后的光信号在光纤1中传输时所产生的返回光经由波分复用器310返回至光时域反射仪210，以便光时域反射仪210按照上述实施例一中的计算方式确定光纤1的性能；
在测量光纤2时，C+L波分复用系统中还可以包括光时域反射仪220，光时域反射仪220连接波分复用器320的通信端a 34，用于向波分复用器320发送波长为λ 21和λ 22的两种测量光。如此，C波段放大器511发出的放大后的C波段信号光、L波段放大器512发出的L波段信号光、以及光时域反射仪220发出的两种波长的测量光会同时且同向地进入波分复用器320，经由波分复用器320合波后耦合进光纤2，而合波后的光信号在光纤2中传输时所产生的返回光经由波分复用器320返回至光时域反射仪220，以便光时域反射仪220按照上述实施例一中的计算方式确定光纤2的性能；
在测量光纤1和光纤2时，C+L波分复用系统中还可以同时包括光时域反射仪210和光时域反射仪220，光时域反射仪210用于对光纤1进行测量，光时域反射仪220用于对光纤2进行测量。且，由于光纤1和光纤2的连接处设置有波分解复用器410，而波分解复用器410能从光纤1传输过来的信号中解出两个波段的信号光并发送给各自的放大器进行放大，并将从光纤1传输过来的信号中解出的其它信号丢弃，也即是说，这两个光时域 反射仪的测量过程互不影响。因此，光时域反射仪210发出的两种测量光的波长λ 11、λ 12与光时域反射仪220发出的两种测量光的波长λ 21、λ 22可以相同，也可以不同，具体不作限定。该测量方案既可以对位于发送端传输的光纤1进行测量，也能对位于中间跨段传输的光纤2进行测量，通过在每一跨段光纤的一端放置光时域反射仪，能完成对光纤系统中的每一段光纤性能的单向测量。
在一种可选地实施方式中，继续参照图5所示，以测量光纤1为例，C+L波分复用系统中还可以同时包括光时域反射仪210和光时域反射仪230，光时域反射仪210和光时域反射仪230分别位于光纤1的两端。例如，光时域反射仪210连接位于光纤1图示左侧一端(图中示出的是光纤1的上游一端，即接收信号光的一端)的波分复用器310的通信端a 14，用于向波分复用器310发送波长为λ 11和波长为λ 12的两种测量光，而光时域反射仪230连接位于光纤1图示右侧一端(图中示出的是光纤1的下游一端，即发出信号光的一端)的波分解复用器410的通信端a 24，用于向波分解复用器410发送波长为λ 31和波长为λ 32的两种测量光。如此，一方面，光时域反射仪210发出的两种测量光能通过波分复用器310与信号光同向耦合进光纤1的上游，以便光时域反射仪210根据返回光获得自光纤1的上游节点处测量得到的第一目标性能曲线(如图6中(A)所示)；另一方面，光时域反射仪230发出的两种测量光则可以通过波分解复用器410从光纤1的下游直接耦合进光纤1，使得光时域反射仪230根据返回光获得自光纤1的下游节点处测量得到的第二目标性能曲线(如图6中(B)所示)。
通常情况下，测量光在光纤中传输时其功率会随着传输距离的增加而不断减小，因此单个测量方向的测量精度会随着测量距离的增长而降低，在距离光时域反射仪越远的位置，测量光的功率越低。同时，单向测量只能得到一个方向上的功率损耗，在光纤挤压处、有损连接器或不同芯径光纤拼接处无法区分出具体的损伤原因，对光纤中的“事件”描述不够精准，尤其是在距离光时域反射仪较远的一端，对“事件”的分辨能力进一步降低。因此，上述实施方式通过在光纤的两端分别放置光时域反射仪，能通过两个光时域反射仪完成光纤的双向测量，获得光纤中每个位置处在两个方向的损耗信息，这不仅有助于更准确地量化损耗，准确定位光纤中存在的问题(包括但不限于光纤挤压处、有损连接器或不同芯径光纤拼接处的具体损伤原因)，提高测量光纤的精确和细致程度，还能通过两个方向的测量覆盖单个方向测量时所存在的测试盲区，有效扩大测量的有效范围。例如，参照图6中(A)和图6中(B)所示，光纤中的位置P1在沿着图示自左向右的方向测量时存在突增+0.02dB的功率损耗，而在沿着图示自右向左的方向测量时存在突降-0.08dB的功率损耗，根据这一正一负的功率损耗，可以准确定位出位置P1处可能存在光纤挤压的问题。相应地，光纤中的位置P2在沿着图示自左向右的方向测量时存在突降-0.12dB的功率损耗，而在沿着图示自右向左的方向测量时存在突降-0.02dB的功率损耗，根据这两负的功率损耗，可以准确定位出位置P2处可能存在光纤拼接的问题。
示例性地，在上述实施方式中，光时域反射仪210发出的两种测量光的波长λ 11、λ 12不同于光时域反射仪230发出的两种测量光的波长λ 31、λ 32，如此，即使一个光时域反射仪发出的测量光进入对侧的光时域反射仪，也会由于不同于对侧的光时域反射仪发出的测量光的波长而被对侧的光时域反射仪过滤掉，而不是被光时域反射仪用来分析光纤的性能，有助于提高在每个方向上测量光纤的准确性。
应理解，上述实施例二只是以C+L光纤系统为例进行介绍，当光纤系统只传输单波段 信号光时，图3所示出的C波段放大器511和L波段放大器512也可以由一个光纤放大器来代替，或者，当光纤系统同时传输三种或三种以上波段的信号光时，图3所示出的C波段放大器511和L波段放大器512还可以由三个或三个以上的放大器来代替，本申请对此不再一一重复赘述。
【实施例三】
图7示例性示出本申请实施例提供的一种测量芯分复用系统的架构示意图，其中，芯分复用系统中的光纤具体可以为多芯光纤，即一根光纤中包含多个纤芯。如图7所示，在该示例中，芯分复用系统中可以包括M个多芯光纤(即多芯光纤1、多芯光纤2、……、多芯光纤M，M为正整数)，假设M个多芯光纤中的每个多芯光纤包含T个纤芯，则芯分复用系统中还可以包括与多芯光纤1中的T个纤芯一一对应的T个波分复用模组(即波分复用模组1、波分复用模组2、……、波分复用模组T，T为大于或等于2的正整数)、扇入扇出器件700、光纤放大器510、……、光纤放大器5M0和信号接收器600。其中，T个波分复用模组中的每个波分复用模组都可以包含一个信号发生器、一个光时域反射仪和一个波分复用器，针对于每个波分复用模组：信号发生器向波分复用器发送信号光，光时域反射仪向波分复用器发送波长分别位于信号光的波长两侧的两种测量光，波分复用器对两种测量光和信号光合波后发出。扇入扇出器件700可以包括T个第一端和一个第二端，T个波分复用模组分别连接扇入扇出器件700的T个第一端，扇入扇出器件700的第二端连接多芯光纤1的一端，多芯光纤1的另一端连接光纤放大器510。关于该方案中的光纤放大器510、……、光纤放大器5M0和信号接收器600的实现过程，均与上述实施例二中一致，区别仅在于该实施例将上述实施例二中的两个放大器合成为一个放大器进行概述，应理解，如果实施例三中的多芯光纤1上也传输多波段信号，则光纤放大器510也可以如上述实施例二中所述的包含多个波段分别对应的放大器，且多芯光纤1与多个放大器之间还可以设置波分解复用器，本申请对此不再一一重复介绍。
本申请实施例可以对芯分复用系统中的一根多芯光纤或多根多芯光纤进行测量：
在测量多芯光纤1时，T个波分复用模组可以分别将各自合波得到的光信号(下文称为复合光信号)发送至扇入扇出器件700的T个第一端，由扇入扇出器件700将T个复合光信号分别耦合至多芯光纤1的T个纤芯中，以实现T个复合光信号在同一根光纤中的芯分复用传输。之后，每个复合光信号在所对应的纤芯中传输时，产生的背向返回光会沿着传输方向的反方向回到扇入扇出器件700的第二端，由扇入扇出器件700通过该复合光信号所对应的第一端传输给该纤芯对应的波分复用模组中的波分复用器，进而由波分复用器对应的光时域反射仪所接收。每个光时域反射仪接收到该波分复用模组对应的纤芯的返回光后，根据该返回光可以确定出该纤芯的性能。通过设置每个纤芯对应的光时域反射仪，能实现对多芯光纤中的每个纤芯的性能测量。
本申请实施例中，光纤放大器510可以设置为对应T个信号发生器1-T所发出的T个信号光的波段，多芯光纤1输出的信号传输至光纤放大器510(或通过如实施例二中的波分解复用器分波出不同波段的信号光后发送至各自波段对应的放大器)，经由光纤放大器510对其中的信号光进行功率放大后进入下一段多芯光纤，而其中的测量光则不再进一步传输。如此，通过设置光纤放大器对经由上一段光纤传输过来的较弱的信号光进行功率放大，能补偿经由多段多芯光纤传输所导致的光功率损耗，实现信号的长距离传输，且还能 避免测量光进入下一段光纤而导致上一段光纤的测量光对下一段光纤的测量过程造成干扰，有助于提高测量下一段光纤的准确性。
在测量除多芯光纤1以外的其它多芯光纤(例如多芯光纤M)时，芯分复用系统中还可以包含扇入扇出器件7M0、与多芯光纤M中的T个纤芯一一对应的T个波分复用器3M1-3MT、与T个波分复用器3M1-3MT一一对应的T个光时域反射仪1M1-1MT、扇入扇出器件7M1。其中，扇入扇出器件7M0可以包括一个输入端和T个输出端，扇入扇出器件7M1可以包括T个第一端和一个第二端，扇入扇出器件7M0的输入端连接上一段光纤，扇入扇出器件7M0的T个输出端分别连接T个波分复用器3M1-3MT的输入端，T个光时域反射仪1M1-1MT分别连接T个波分复用器3M1-3MT的第一通信端，T个波分复用器3M1-3MT的第二通信端分别连接扇入扇出器件7M1的T个第一端，扇入扇出器件7M1的第二端连接多芯光纤M的一端，多芯光纤M的另一端连接光纤放大器5M0的输入端，光纤放大器5M0的输出端连接信号接收器600。在测量多芯光纤M时，扇入扇出器件7M0可以分别将上一段光纤中的T个纤芯传输过来的T个光信号发送给T个波分复用器3M1-3MT，而T个光时域反射仪1M1-1MT可以分别向各自对应的波分复用器3M1-3MT发送两种不同波长的测量光，每个光时域反射仪发出的两种测量光通过所对应的波分复用器与上一段光纤中对应纤芯传输过来的光信号合波为复合光信号后发送给扇入扇出器件7M1，由扇入扇出器件7M1将接收到的T个复合光信号分别耦合至多芯光纤M的T个纤芯，以实现T个复合光信号在多芯光纤M中的芯分复用传输。之后，每个复合光信号在所对应的纤芯中传输时，产生的背向返回光会沿着传输方向的反方向回到扇入扇出器件7M1的第二端，由扇入扇出器件7M1传输给该纤芯对应的波分复用器，进而由该波分复用器转发给对应的光时域反射仪。光时域反射仪1M1-1MT中的每个光时域反射仪接收到多芯光纤M中的对应纤芯的返回光后，根据该返回光可以确定出多芯光纤M中的对应纤芯的性能。通过在多芯光纤M的图示左侧一端设置T个光时域反射仪，能获得图示自左向右方向测量得到的多芯光纤M中的每个纤芯的性能。
根据上述内容可知，图7所示的光纤测量系统可以实现对一个或多个纤芯的单向测量。且，上述内容都是以同时测量T个纤芯为例进行介绍的，在实际操作中，可以通过多个纤芯分别对应的多个光时域反射仪同时发送测量光来实现对多个纤芯的同步测量，以提高测量的效率，也可以是每次只通过一个光时域反射仪发送测量光来实现对一个纤芯的测量，以降低不同测量的干扰，当然还可以是多次测量，且在每次测量中通过对应的部分光时域反射仪发送测量光来实现对其中部分纤芯的测量，具体不作限定。另外，以多芯光纤M为例，在同时测量多芯光纤M及位于多芯光纤M之前的某一段或多段多芯光纤时，为进一步避免位于多芯光纤M之前的某一段或多段多芯光纤所采用的测量光对多芯光纤M的测量过程造成干扰，一种可能的实现中，还可以在扇入扇出器件7M0的每个输出端和所对应的波分复用器之间设置一个波分解复用器，通过波分解复用器解出上一段多芯光纤传输过来的复合光信号中的信号光和非信号光(如测量光)后，将解出的信号光发送给所对应的波分复用器，将解出的非信号光丢弃或发送给额外设置的其它接收设备。该实现能保证只让前一段多芯光纤传输过来的信号光进入波分复用器，进而与测量多芯光纤M的测量光一起耦合至多芯光纤M，如此，即使多芯光纤M和位于多芯光纤M之前的其它多芯光纤采用相同波长的测量光，也不会对多芯光纤M的测量过程产生干扰，有效提高多芯光纤M的测量准确性。
本申请中的光纤测量方案还可以实现对一个或多个纤芯的双向测量，例如以测量多芯光纤1为例，图8示例性示出本申请实施例提供的另一种测量芯分复用系统的架构示意图，如图8所示，如果想实现对多芯光纤1中的一个或多个纤芯进行双向测量，则还可以设置扇入扇出器件701、与多芯光纤1中的T个纤芯一一对应的T个波分解复用器411-41T、与T个波分解复用器411-41T一一对应的T个光时域反射仪21-2T、以及扇入扇出器件702。其中，扇入扇出器件701包括一个第一端和T个第二端，扇入扇出器件702包括T个输入端和一个输出端，扇入扇出器件701的第一端用于连接多芯光纤1的另一端，扇入扇出器件701的T个第二端分别连接T个波分解复用器411-41T的第一通信端，T个光时域反射仪21-2T分别连接T个波分解复用器411-41T的第二通信端，T个波分解复用器411-41T的输出端分别连接扇入扇出器件702的T个输入端，扇入扇出器件702的输出端连接光纤放大器510。
参照图8所示意的系统架构，在需要同时双向测量多芯光纤1中的T个纤芯时，除了T个波分复用模组中的T个光时域反射仪1-T分别发出两种不同波长的正向的测量光之外，还可以通过T个光时域反射仪21-2T分别发出两种不同波长的反向的测量光。如此，T个光时域反射仪1-T发出的正向的测量光通过扇入扇出器件700分别正向耦合至多芯光纤1的T个纤芯中，以便按照上述内容按照图示自左向右方向测量得到多芯光纤1中的T个纤芯的第一目标性能曲线。且，通过多芯光纤1传输至扇入扇出器件701的T个纤芯的信号通过扇入扇出器件701分别耦合至各自对应的波分解复用器411-41T，进而通过各自的波解复用器将其中的信号光转发至扇入扇出器件702，由扇入扇出器件702分别耦合至下一段光纤中的T个纤芯。对应的，T个光时域反射仪21-2T发出的反向的测量光会通过各自对应的波分解复用器411-41T耦合至扇入扇出器件701的T个第二端，之后通过扇入扇出器件701分别反向耦合至多芯光纤1中的T个纤芯，并沿着图示自右向左的方向在多芯光纤1中传输。之后，多芯光纤1中的T个纤芯的返回光回到扇入扇出器件701后，通过扇入扇出器件701分别耦合至各自对应的T个波分解复用器411-41T，进而转发给各自对应的T个光时域反射仪21-2T，由每个光时域反射仪根据所对应光纤的返回光，确定图示自右向左方向测量得到的多芯光纤1中的T个纤芯的第二目标性能曲线。如此，通过在多芯光纤1的两端分别设置每个纤芯对应的两个光时域反射仪，能实现对多芯光纤1中的每个纤芯的双向测量，提供多芯光纤1中的每个纤芯在同一位置处的两个方向的损耗信息，有助于更准确地量化每个纤芯的损耗，以及扩大每个纤芯的有效测量范围，有效提高对芯分复用系统中每个纤芯测量的准确性。
需要指出的是，上述内容只是以同时双向测量多芯光纤1中的T个纤芯为例进行介绍。在其它示例中，如果只需要测量多芯光纤1中的一个纤芯，则可以只通过该纤芯对应的波分复用模组中的正向设置的光时域反射仪发送正向的测量光，以及通过该纤芯对应的反向设置的光时域反射仪发送反向的测量光，而其它纤芯对应的波分复用模组中的光时域反射仪和反向设置的光时域反射仪则可以不发送测量光。且，在双向测量多芯光纤1的每个纤芯时，位于该纤芯两端的两个光时域反射仪发出的测量光的波长各不相同，例如：假设光时域反射仪1发出波长λ 11和λ 12的两个测量光以正向测量多芯光纤1中的某一个纤芯，光时域反射仪21发出波长λ 13和λ 14的两个测量光以反向测量多芯光纤1中的该纤芯，则波长λ 11、λ 12、λ 13和λ 14各不相同。如此，即使光时域反射仪1发出的波长λ 11和λ 12的两个测量光会进入对侧的光时域反射仪21，由于该波长与光时域反射仪21发出的测量光的波长λ 13 和λ 14不同，因此也不会被光时域反射仪21用来分析多芯光纤1中的该纤芯的反向性能，反之也是一样，可知，该种波长设置方式有助于提高在每个方向上测量多芯光纤1中的纤芯的准确性。另外，双向测量多芯光纤2至多芯光纤M中的每个中间多芯光纤的方式可以参照上述双向测量多芯光纤1中的方式实现，例如如果想实现对某一个中间多芯光纤中的T个纤芯的双向测量，则还可以按照如图8中设置T个正向的光时域反射仪1-T、以及T个反向的光时域反射仪21-2T的方式，在所需测量的中间多芯光纤的两端分别设置T个正向的光时域反射仪和T个反向的光时域反射仪，该部分内容的具体实现，请参照上述实施例中关于多芯光纤1的内容介绍，此处不再一一重复赘述。
【实施例四】
图9示例性示出本申请实施例提供的一种测量模分复用系统的架构示意图，其中，模分复用系统中的光纤具体可以为少模光纤，即一根光纤中可以同时传输不同模式的光信号。如图9所示，在该示例中，模分复用系统中可以包括N个少模光纤(即少模光纤1、少模光纤2、……、少模光纤N，N为正整数)，还可以包括R个波分复用模组(即波分复用模组1、波分复用模组2、……、波分复用模组R，R为大于或等于2的正整数)、模式复用器800、光纤放大器510、……、光纤放大器5N0和信号接收器600。其中，R个波分复用模组中的每个波分复用模组的结构请参照上述实施例三，此处不再重复说明。模式复用器800可以包括R个第一端和一个第二端，R个波分复用模组分别连接模式复用器800的R个第一端，模式复用器800的第二端连接少模光纤1的一端，少模光纤1的另一端连接光纤放大器510。关于该方案中的光纤放大器510、光纤放大器5N0和信号接收器600的连接关系及实现过程，均与上述实施例三中一致，本申请对此不再一一重复介绍。
本申请实施例可以对模分复用系统中的一根少模光纤或多根少模光纤进行测量：
在测量少模光纤1时，R个波分复用模组可以分别将各自合波得到的基模的复合光信号发送至模式复用器800，由模式复用器800对每个基模的复合光信号生成一种模式后，将R个模式的复合光信号耦合至少模光纤1，以实现不同模式的复合光信号在少模光纤1中的模式复用传输。之后，R个模式的复合光信号在少模光纤1中传输时，产生的背向返回光会沿着传输方向的反方向回到模式复用器800，由模式复用器800对R个模式的返回光进行去模式处理后，获得R个基模的返回光，将R个基模的返回光分别传输给各自对应的波分复用器，进而转发给各自对应的光时域反射仪。每个光时域反射仪根据接收到的返回光，可以确定出少模光纤1在传输该波分复用模组发出的基模的复合光信号被转化的模式时的性能损耗。该方案能沿着图示自左向右方向测量得到每个模式对应的性能，实现对少模光纤1中的每个模式的单向测量。
本申请实施例中，光纤放大器510可以设置为对应R个信号发生器1-R所发出的R个信号光的波段，少模光纤1输出的不同模式的光信号传输至光纤放大器510(或通过如实施例二中的波分解复用器分波为不同波段的信号光后分别发送至各波段对应的放大器)后，经由光纤放大器510对其中的信号光进行功率放大后进入下一段少模光纤，而其中的测量光则不再进一步传输。如此，通过设置光纤放大器对经由上一段少模光纤传输过来的较弱的信号光进行功率放大，能补偿经由多段少模光纤传输所导致的光功率损耗，实现信号的长距离传输，且还能避免测量光进入下一段少模光纤而导致上一段少模光纤的测量光对下一段少模光纤的测量过程造成干扰，有利于提高测量下一段少模光纤的准确性。
在测量除少模光纤1以外的其它少模光纤(例如少模光纤N)时，模分复用系统中还可以包含模式复用器8N0、与少模光纤N中的R个模式一一对应的R个波分复用器3N1-3NR，与R个波分复用器3N1-3NR一一对应的R个光时域反射仪1N1-1NR、模式复用器8N1。其中，模式复用器8N0可以包括一个输入端和R个输出端，模式复用器8N1可以包括R个第一端和一个第二端，模式复用器8N0的输入端连接上一段少模光纤，模式复用器8N0的R个输出端分别连接R个波分复用器3N1-3NR的输入端，R个光时域反射仪1N1-1NR分别连接R个波分复用器3N1-3NR的第一通信端，R个波分复用器3N1-3NR的第二通信端分别连接模式复用器8N1的R个第一端，模式复用器8N1的第二端连接少模光纤N的一端，少模光纤N的另一端连接光纤放大器5N0的输入端，光纤放大器5N0的输出端连接信号接收器600。在测量少模光纤N时，模式复用器8N0可以对上一段少模光纤传输过来的R个模式的光信号进行去模式处理后，获得R个基模的光信号并分别发送给R个波分复用器3N1-3NR，而R个光时域反射仪1N1-1NR可以分别向各自对应的R个波分复用器3N1-3NR发送两种不同波长的测量光，每个光时域反射仪发出的两种测量光通过所对应的波分复用器与上一段光纤传输过来的对应基模的光信号合波为复合光信号后发送给模式复用器8N1，由模式复用器8N1生成R个基模的复合光信号所对应的R个模式的复合光信号后耦合至少模光纤N，以实现R个模式的复合光信号在少模光纤N中的模分复用传输。之后，每个模式的复合光信号在少模光纤N中传输时，产生的背向返回光会沿着传输方向的反方向回到模式复用器8N1的第二端，由模式复用器8N1对R个模式的返回光进行去模式处理后，获得R个基模的返回光并分别发送给各自对应的R个波分复用器3N1-3NR，通过所对应的波分复用器传输给每个模式对应的光时域反射仪。光时域反射仪1N1-1NR中的每个光时域反射仪接收到少模光纤N中对应基模的返回光后，根据该返回光可以确定出少模光纤N中对应模式的性能。通过在少模光纤N的图示左侧一端设置R个光时域反射仪，能获得图示自左向右测量得到的少模光纤N中的每个模式的性能。
根据上述内容可知，图9所示的光纤测量系统可以实现对一个或多个模式的单向测量。且，上述内容都是以同时测量R个模式为例进行介绍的，在实际操作中，可以通过多个模式分别对应的多个光时域反射仪同时发送测量光来实现对多个模式的同步测量，以提高测量的效率，也可以是每次只通过一个光时域反射仪发送测量光来实现对一个模式的测量，以降低不同测量的干扰，当然还可以是多次测量，且在每次测量中通过对应的部分光时域反射仪发送测量光来实现对其中部分模式的测量，具体不作限定。另外，以少模光纤N为例，在同时测量少模光纤N及位于少模光纤N之前的某一段或多段少模光纤时，为进一步避免位于少模光纤N之前的某一段或多段少模光纤所采用的测量光对少模光纤N的测量过程造成干扰，一种可能的实现中，还可以在模式复用器8M0的每个输出端和所对应的波分复用器之间设置一个波分解复用器，通过波分解复用器解出上一段少模光纤传输过来的复合信号中的信号光和非信号光(如测量光)后，将解出的信号光发送给所对应的波分复用器，将解出的非信号光丢弃或发送给额外设置的其它接收设备。该实现能保证只让前一段少模光纤传输过来的信号光进入波分复用器，进而与测量少模光纤N的测量光一起转换模式后耦合至少模光纤N，如此，即使少模光纤N和位于少模光纤N之前的其它少模光纤采用相同波长的测量光，也不会对少模光纤N的测量过程产生干扰，有效提高少模光纤N的测量准确性。
本申请中的光纤测量方案还可以实现对一个或多个模式的双向测量，例如以测量少模 光纤1为例，图10示例性示出本申请实施例提供的另一种测量模分复用系统的架构示意图，如图10所示，如果想实现对少模光纤1中的一个或多个模式的双向测量，则还可以设置模式复用器801、与少模光纤1中的R个模式一对应的R个波分解复用器411-41R、与R个波分解复用器411-41R一一对应的R个光时域反射仪21-2R、以及模式复用器802。其中，模式复用器801包括一个第一端和R个第二端，模式复用器802包括R个输入端和一个输出端，模式复用器801的第一端用于连接少模光纤1的另一端，模式复用器801的R个第二端分别连接R个波分解复用器411-41R的第一通信端，R个光时域反射仪21-2R分别连接R个波分解复用器411-41R的第二通信端，R个波分解复用器411-41R的输出端分别连接模式复用器802的R个输入端，模式复用器802的输出端连接光纤放大器510。
参照图10所示意的系统架构，在需要同时双向测量少模光纤1中的R个模式时，除了R个波分复用模组中的R个光时域反射仪1-R分别发出两种不同波长的正向的测量光之外，还可以通过R个光时域反射仪21-2R分别发出两种不同波长的反向的测量光。如此，R个光时域反射仪1-R发出的正向的测量光通过模式复用器800转换为R种模式后正向耦合至少模光纤1中，以便按照上述内容沿着图示自左向右方向测量得到少模光纤1中的R个模式的第一目标性能曲线。且，通过少模光纤1传输至模式复用器801的信号通过模式复用器801去模式处理后恢复为基模信号，之后经过各自对应的波分解复用器将其中的基模的信号光耦合至模式复用器802的R个第一端，由模式复用器802生成R个基模的信号光对应的R个模式的信号光后发送给光纤放大器510以放大并传输至下一段光纤。对应的，R个光时域反射仪21-2R发出的反向的测量光会通过各自对应的波分解复用器411-41R耦合至模式复用器801的R个第二端，之后通过模式复用器801转换为R种模式后反向耦合至少模光纤1中，并沿着图示自右向左的方向在少模光纤1中传输。之后，少模光纤1的R个模式的返回光回到模式复用器801后，通过模式复用器801去模式处理后分别耦合至各自对应的R个波分解复用器411-41R，进而转发给各自对应的R个光时域反射仪21-2R，由每个光时域反射仪根据所对应模式的返回光，确定图示自右向左方向测量得到的少模光纤1中的R个模式的第二目标性能曲线。如此，通过在少模光纤1的两端分别设置每个模式对应的两个光时域反射仪，能实现对少模光纤1中的每个模式的双向测量，提供少模光纤1中每个模式在同一位置处的两个方向的损耗信息，有助于更准确地量化每个模式的损耗，以及扩大每个模式的有效测量范围，有效提高对模分复用系统中每个模式测量的准确性。
需要指出的是，上述内容只是以同时双向测量少模光纤1中的R个模式为例进行介绍。在其它示例中，如果只需要测量少模光纤1中的某种模式，则可以只通过一个波分复用模组中的正向设置的光时域反射仪发送正向的测量光，以及通过该模式对应的反向设置的光时域反射仪发送反向的测量光，而其它波分复用模组中的光时域反射仪和反向设置的光时域反射仪则可以不发送测量光。如此，波分复用模组中的正向设置的光时域反射仪发出的测量光与信号光同向发送至模式复用器800一侧，由模式复用器800转化为待测量的模式后耦合至少模光纤1的图示左侧一端，并沿着图示自左向右的方向在少模光纤1中传输，波分复用模组中的光时域反射仪根据返回光，可以确定图示自左向右方向测量得到的少模光纤1传输该模式的信号的第一目标性能曲线。对应的，反向设置的光时域反射仪可以向对应的波分复用器发送两种不同波长的测量光，通过波分复用器耦合至模式复用器801后，通过模式复用器801转化为待测量的模式后耦合至少模光纤1的图示右侧一端，并沿着图 示自右向左的方向在少模光纤1中传输，该种模式的测量光在少模光纤1传输时，产生的返回光回到模式复用器801，由模式复用器801去模式后转发给对应的波分解复用器，进而转发给对应的光时域反射仪，由光时域反射仪根据两种测量光对应的同一模式的返回光，沿着图示自右向左方向测量得到少模光纤1传输该模式的第二目标性能曲线。结合正向测量得到的该模式的第一目标性能曲线和反向测量得到的该模式的第二目标性能曲线，可以准确分析少模光纤1在传输该模式时的性能。
另外，在双向测量少模光纤1中的每个模式时，位于少模光纤1两端的两个光时域反射仪发出的测量光的波长各不相同，例如：假设光时域反射仪R发出波长λ R1和λ R2的两个测量光以正向测量少模光纤1中的某一模式，光时域反射仪2R发出波长λ R3和λ R4的两个测量光以反向测量少模光纤1中的该模式，则波长λ R1、λ R2、λ R3和λ R4各不相同。如此，即使光时域反射仪R发出的波长λ R1和λ R2的两个测量光会进入对侧的光时域反射仪2R，由于该波长与光时域反射仪2R发出的测量光的波长λ R3和λ R4不同，因此也不会被光时域反射仪2R用来分析少模光纤1中的该模式的反向性能，反之也是一样，可知，该种波长设置方式有助于提高在每个方向上测量少模光纤中模式的准确性。
应理解，双向测量少模光纤2至少模光纤N中的每个中间少模光纤的方式可以参照上述双向测量少模光纤1中的方式实现，例如如果想实现对某一个中间少模光纤中的R个模式的双向测量，则还可以按照如图10中设置R个正向的光时域反射仪1-R、以及R个反向的光时域反射仪21-2R的方式，在所需测量的中间少模光纤的两端分别设置R个正向的光时域反射仪和R个反向的光时域反射仪，该部分内容的具体实现，请参照上述实施例中关于少模光纤1的内容介绍，此处不再一一重复赘述。
另外，少模光纤在同时传输不同模式的信号时，不同模式之间可能会存在弱耦合，也即是不同模式之间虽然会产生信号串扰但并不强烈，该信号串扰可以直接忽略，也可以通过在光时域反射仪侧设置数字信号处理(digital signal processing，DSP)的方式进行噪声消除。此外，少模光纤在传输同一信号的不同模式时还可能会产生群时延，导致同一测量时长所得到的返回光可能对应不同的光纤位置，这种返回光和位置的错位关系也可以在光时域反射仪侧通过DSP的方式进行恢复。关于DSP的具体实现方式，可以参照现有方案，本申请对此不做过多介绍。
需要说明的是，在上述实施例一至实施例四中，返回的光中可以包括散射光和反射光，也可以包括其它类型的返回光，具体不作限定。
假设返回的光中包含散射光，下面以测量图9中的少模光纤N为例，进一步介绍在不同受激散射效应下的测量过程。在该示例中，假设少模光纤N的上游一端设置有两个光时域反射仪1N1和1N2、以及两个波分复用器3N1和3N2：
图11示例性示出本申请实施例提供的一种不同模式下的信号流转示意图，如图11所示，在该示例中，光时域反射仪1N1可以向波分复用器3N1发送波长为λ N1的测量光和波长为λ N2的测量光，且λ N1和λ N2分别位于上一段少模光纤发送过来的信号光的波长λ 01的两侧，波长为λ N1的测量光、波长为λ N2的测量光和波长为λ 01的信号光经由波分复用器3N1合波后耦合至模式复用器8N1；光时域反射仪1N2可以向波分复用器3N2发送波长为λ N3的测量光和波长为λ N4的测量光，且λ N3和λ N4分别位于上一段少模光纤发送过来的信号光的波长λ 02的两侧，波长为λ N3的测量光、波长为λ N4的测量光和波长为λ 02的信号光经由波 分复用器3N2合波后耦合至模式复用器8N1。模式复用器8N1可以生成波长为λ N1的测量光、波长为λ N2的测量光和波长λ 01的信号光对应的一种模式LP1，获得测量光信号LP1 λN1、测量光信号LP1 λN2和信号光信号LP1 λ01，以及生成波长为λ N3的测量光、波长为λ N4的测量光和波长λ 02的信号光对应的另一种模式LP2，获得测量光信号LP2 λN3、测量光信号LP2 λN4和信号光信号LP1 λ02，进而将这两种模式下的四个测量光信号和两个信号光信号一起耦合至少模光纤N。进一步地：
当测量光的功率强度小于布里渊散射的发生门限时，测量光信号LP1 λN1、LP1 λN2、LP2 λN3和LP2 λN4在少模光纤N中传输时，会发生背向瑞利散射而不发生布里渊散射，也即是说，只会发生功率转移而不发生波长偏移。因此，在少模光纤N上的不同模式的返回光信号到达模式复用器8N1后，由模式复用器8N1对返回光信号LP1 λN1和LP1 λN2进行去模式处理后获得对应的返回光信号，并经由波分复用器3N1返回给光时域反射仪1N1，模式复用器8N1对返回光信号LP2 λN3和LP2 λN4进行去模式处理后获得对应的返回光信号，并经由波分复用器3N2返回给光时域反射仪1N2。光时域反射仪1N1可以从返回光信号里面过滤出与测量光信号的波长λ N1和λ N2一致的返回光信号，根据波长λ N1的返回光信号确定模式LP1的第一瑞利散射性能损耗曲线，根据波长λ N2的返回光信号确定模式LP1的第二瑞利散射性能损耗曲线，加权这两个瑞利散射性能损耗曲线，可以获得模式LP1对应的目标瑞利散射性能损耗曲线。光时域反射仪1N2可以从返回光信号里面过滤出与测量光信号的波长λ N3和λ N4一致的返回光信号，根据波长λ N3的返回光信号确定模式LP2的第一瑞利散射性能损耗曲线，根据波长λ N4的返回光信号确定模式LP2的第二瑞利散射性能损耗曲线，加权这两个瑞利散射性能损耗曲线，可以获得模式LP2对应的目标瑞利散射性能损耗曲线。之后，如果还想获知少模光纤N对两种模式的综合瑞利散射性能，则还可以对少模光纤N在两种模式下的目标瑞利散射性能损耗曲线进行平均，获得少模光纤N的综合瑞利散射性能损耗曲线。
当测量光的功率强度不小于布里渊散射的发生门限时，测量光信号LP1 λN1、LP1 λN2、LP2 λN3和LP2 λN4在少模光纤N中传输时，会同时发生背向瑞利散射和布里渊散射，也即是说，同时发生功率转移和波长偏移。因此，在少模光纤N上的不同模式的返回光信号通过模式复用器8N1去模式处理，并经由波分复用器3N1和波分复用器3N2分别返回至光时域反射仪1N1和光时域反射仪1N2后，一方面，可以由光时域反射仪1N1从返回光信号里面获得与测量光信号的波长λ N1和λ N2一致的返回光信号，按照上述方式获得模式P1对应的目标瑞利散射功率损耗曲线，由光时域反射仪1N2从返回光信号里面获得与测量光信号的波长λ N3和λ N4一致的返回光信号，按照上述方式获得模式P2对应的目标瑞利散射功率损耗曲线，或者进而获得少模光纤N的综合瑞利散射功率损耗曲线。另一方面，还可以由光时域反射仪1N1从返回光里面获得与测量光信号的波长λ N1和λ N2存在一定偏移的返回信号，根据模式P1下的存在一定偏移的每种波长的返回光信号确定每种波长在模式P1下的布里渊散射性能损耗曲线，加权模式P1下的波长λ N1和λ N2的两个布里渊散射性能损耗曲线，可以获得模式P1对应的目标布里渊散射性能损耗曲线。由光时域反射仪1N2从返回光里面获得与测量光信号的波长λ N3和λ N4存在一定偏移的返回光信号，根据模式P2下的存在一定偏移的每种波长的返回光信号确定每种波长在模式P2下的布里渊散射性能损耗曲线，加权模式P2下的波长λ N3和λ N4的两个布里渊散射性能损耗曲线，可以获得模式P2对应的目标布里渊散射性能损耗曲线。且，如果还想获知少模光纤N对两种模式的综 合布里渊散射性能，则还可以对少模光纤N在两种模式下的目标布里渊散射性能损耗曲线进行平均，获得少模光纤N的综合布里渊散射性能损耗曲线。
需要说明的是，布里渊散射所对应的波长偏移可以通过实验确定，实验过程包括：分别激发同一波长的不同模式，并测得该波长在每种模式下的布里渊返回光的频率偏移，按照频率和波长的相关关系计算出频率偏移对应的波长偏移。如此，光时域反射仪1N1在获得返回光后，可以根据实验确定的模式P1下的布里渊返回光的波长偏移和测量光的波长，确定布里渊散射所导致的返回光的应有波长，从返回光中找到该应有波长对应的返回光，以构建模式P1对应的布里渊散射性能损耗曲线。以及，光时域反射仪1N2在获得返回光后，可以根据实验确定的模式P2下的布里渊返回光的波长偏移和测量光的波长，确定布里渊散射所导致的返回光的应有波长，从返回光中找到该应有波长对应的返回光，以构建模式P2对应的布里渊散射性能损耗曲线。
示例性地，当需要测量的模式中包含一些比较相近的模式时，还可以将比较相近的模式划分至不同的模式集合，得到至少两组模式集合，并分别对至少两组模式集合进行单独测量。例如，如果需要测量的模式包括模式1、模式2、模式3和模式4，且模式1和模式2比较相近，模式3和模式4比较相近，则可以将模式1和模式3划分至第一组模式集合，将模式2和模式4划分至第二组模式集合(或者，也可以将模式1和模式4划分至第一组模式集合，将模式2和模式3划分至第二组模式集合)，先针对于第一组模式集合中的两个模式进行测量，获得模式1对应的性能曲线和模式3对应的测量性能曲线，再对第二组模式集合中的两个模式进行测量，获得模式2对应的性能曲线和模式4对应的性能曲线。如此，通过将相近的模式划分在不同的模式集合中单独进行测量，而不是放在同一模式集合中一起测量，能降低相近模式在同一次测量中的相互干扰，进一步提高光纤测量的准确性。
需要说明的是，在上述实施例四中，使用模式复用器产生不同的模式只是一种可选地实施方式，本申请并不限定必须使用模式复用器来产生不同的模式。例如，在另一种可选地实施方式中，也可以通过偏移方式激发出不同的模式。此外，本申请的上述实施例只是以单波长测量光为例进行介绍，但该测量方案也可以适用于多波长测量光，相关执行过程可以直接参照上述内容，本申请对此不再重复介绍。
基于上述内容，本申请还提供一种光时域反射仪，该光时域反射仪连接波分复用器的第一端，波分复用器的第二端连接信号发生器，波分复用器的第三端连接光纤，该光时域反射仪可以用于执行如上述实施例一至实施例四中任一光时域反射仪所执行的步骤。
基于上述内容，本申请还提供一种光纤测量装置，包括上述内容介绍的任一光时域反射仪和波分复用器。
基于上述内容，本申请提供一种芯片，该芯片可以包括处理器和接口，处理器用于通过接口读取指令，以执行如上述实施例一至实施例四中任一光时域反射仪所执行的步骤。
基于上述内容，本申请提供一种计算机可读存储介质，该计算机可读存储介质中存储有计算机程序，当计算机程序被运行时，实现如上述实施例一至实施例四中任一光时域反射仪所执行的步骤。
基于上述内容，本申请提供一种计算机程序产品，当所述计算机程序产品在处理器上运行时，实现如上述实施例一至实施例四中任一光时域反射仪所执行的步骤。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟 悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (17)

  1. 一种光纤测量系统，其特征在于，包括：
    信号发生器，用于向波分复用器发送信号光；
    第一光时域反射仪，用于向所述波分复用器发送第一测量光和第二测量光，所述第一测量光的波长和所述第二测量光的波长分别位于所述信号光的波长两侧；
    所述波分复用器，用于对所述第一测量光、所述第二测量光和所述信号光进行合波处理后发送至光纤，以及将所述光纤中返回的光发送至所述第一光时域反射仪；
    所述第一光时域反射仪，还用于根据所述返回的光确定所述光纤的性能。
  2. 如权利要求1所述的系统，其特征在于，所述信号光为多波长信号光；
    所述第一测量光的波长和所述第二测量光的波长分别位于所述信号光的波长两侧，包括：
    所述第一测量光的波长大于所述多波长信号光的最大波长，所述第二测量光的波长小于所述多波长信号光的最小波长。
  3. 如权利要求2所述的系统，其特征在于，所述第一测量光的波长与所述最大波长的波长差、以及所述最小波长与所述第二测量光的波长的波长差均位于预设的拉曼增益范围内，所述预设的拉曼增益范围是使两个不同波长的光信号产生明显受激拉曼散射效应的最大波长差。
  4. 如权利要求3所述的系统，其特征在于，所述第一光时域反射仪包括：
    分波器，用于将所述返回的光分波为所述第一测量光对应的第一返回光和所述第二测量光对应的第二返回光，将所述第一返回光和所述第二返回光发送至处理器；
    所述处理器，用于根据所述第一返回光和所述第二返回光，确定所述光纤的性能。
  5. 如权利要求4所述的系统，其特征在于，所述第一测量光的波长与所述信号光的中心波长的波长差和所述信号光的中心波长与所述第二测量光的波长的波长差相同。
  6. 如权利要求4或5所述的系统，其特征在于，所述处理器，具体用于：
    根据所述第一返回光获得所述光纤的第一性能曲线，根据所述第二返回光获得所述光纤的第二性能曲线，加权所述第一性能曲线和所述第二性能曲线，获得所述光纤的目标性能曲线。
  7. 如权利要求6所述的系统，其特征在于，所述第一性能曲线对应的权重和所述第二性能曲线对应的权重的比值与所述信号光的频率与所述第一测量光的频率的频率差和所述第二测量光的频率与所述信号光的频率的频率差的比值正相关。
  8. 如权利要求1至7任一项所述的系统，其特征在于，所述信号发生器包括K个信号发生单元，所述K个信号发生单元与K个波段一一对应，所述K为大于或等于2的正整数；
    所述K个信号发生单元中的每个信号发生单元，用于向所述波分复用器发送位于所对应波段内的信号光。
  9. 如权利要求1至8任一项所述的系统，其特征在于，所述系统还包括波分解复用器和连接所述波分解复用器的第二光时域反射仪，所述波分复用器和所述波分解复用器分别位于所述光纤的两端；
    所述第二光时域反射仪，用于向所述波分解复用器发送第三测量光和第四测量光，所 述第三测量光的波长和所述第四测量光的波长分别位于所述信号光的波长两侧；
    所述波分解复用器，用于将所述第三测量光和所述第四测量光发送至所述光纤，以及将所述光纤返回的光发送至所述第二光时域反射仪；
    所述第二光时域反射仪，还用于根据所述返回的光确定所述光纤在另一方向的性能。
  10. 如权利要求9所述的系统，其特征在于，所述第一测量光、所述第二测量光、所述第三测量光和所述第四测量光的波长互不相同。
  11. 如权利要求9或10所述的系统，其特征在于，所述系统还包括光纤放大器，所述光纤放大器的输入端连接上一段光纤的输出端，所述光纤放大器的输出端连接所述波分复用器；
    所述光纤放大器，用于对所述上一段光纤传输过来的信号光进行功率放大后发送给所述波分复用器。
  12. 如权利要求11所述的系统，其特征在于，所述光纤放大器包括至少两个放大器，所述波分解复用器的输入端连接所述上一段光纤的输出端，所述波分解复用器的至少两个输出端分别连接所述至少两个放大器的输入端，所述至少两个放大器的输出端分别连接所述波分复用器；
    所述波分解复用器，用于将所述上一段光纤传输过来的信号光分波为位于至少两个波段内的光信号，将所述位于至少两个波段内的光信号分别发送给所述至少两个放大器；
    所述至少两个放大器，用于对所接收到的波段内的光信号进行功率放大后发送给所述波分复用器。
  13. 如权利要求1至12中任一项所述的系统，其特征在于，所述光纤为多芯光纤，所述第一光时域反射仪和所述波分复用器的数量为多个，多个所述波分复用器与所述多芯光纤中的多个纤芯一一对应，多个所述波分复用器与多个所述第一光时域反射仪一一对应；所述系统还包括用于连接多个所述波分复用器和所述多芯光纤的第一扇入扇出器件；
    所述第一扇入扇出器件，用于分别将所述波分复用器合波处理后的光发送至与所述波分复用器对应的纤芯，以及将所述多个纤芯返回的光发送至所述多个纤芯各自对应的所述波分复用器；
    所述波分复用器，用于将接收到的纤芯返回的光发送给对应的第一光时域反射仪；
    所述第一光时域反射仪，还用于根据所述纤芯返回的光，确定所述多个纤芯中的对应纤芯的性能。
  14. 如权利要求13所述的系统，其特征在于，所述系统还包括波分解复用器和第二光时域反射仪；
    所述波分解复用器和所述第二光时域反射仪的数量为多个，多个所述波分解复用器与所述多芯光纤中的多个纤芯一一对应，多个所述第二光时域反射仪与所述多个波分解复用器一一对应，所述系统还包括用于连接多个所述波分解复用器和所述多芯光纤的第二扇入扇出器件；
    所述第二光时域反射仪，用于向所连接的波分解复用器发送波长位于所述信号光的波长两侧的两个测量光；
    所述波分解复用器，用于将所连接的第二光时域反射仪发送的两个测量光发送至所述第二扇入扇出器件；
    所述第二扇入扇出器件，用于分别将所述波分解复用器发送的两个测量光耦合至与所 述波分复用器对应的纤芯，以及将所述多个纤芯返回的光发送至所述多个纤芯各自对应的所述波分解复用器；
    所述波分解复用器，还用于将接收到的纤芯返回的光发送给对应的第二光时域反射仪；
    所述第二光时域反射仪，还用于根据所述纤芯返回的光，确定所述多个纤芯中的对应纤芯在另一方向的性能。
  15. 如权利要求1至12任一项所述的系统，其特征在于，所述光纤为少模光纤，所述第一光时域反射仪和所述波分复用器的数量为多个，多个所述波分复用器与所述少模光纤中的多个模式一一对应，多个所述波分复用器与多个所述第一光时域反射仪一一对应；所述系统还包括用于连接多个所述波分复用器和所述少模光纤的第一模式复用器；
    所述第一模式复用器，用于将多个所述波分复用器合波处理后的光转换为不同模式后发送至所述少模光纤，以及对所述少模光纤返回的不同模式的光进行去模式处理后，发送至各自对应的所述波分复用器；
    所述第一光时域反射仪，还用于根据去模式后的返回的光，确定所述少模光纤中对应的模式的性能。
  16. 如权利要求15所述的系统，其特征在于，所述系统还包括波分解复用器和第二光时域反射仪；
    所述波分解复用器和所述第二光时域反射仪的数量为多个，多个所述波分解复用器与所述少模光纤中的多个模式一一对应，多个所述第二光时域反射仪与所述多个波分解复用器一一对应；所述系统还包括用于连接多个所述波分解复用器和所述少模光纤的第二模式复用器；
    所述第二光时域反射仪，用于向所连接的波分解复用器发送波长位于所述信号光的波长两侧的两个测量光；
    所述波分解复用器，用于将所连接的第二光时域反射仪发送的两个测量光发送至所述第二模式复用器；
    所述第二模式复用器，用于将多个所述波分解复用器发送的两个测量光转换为不同模式后发送至所述少模光纤，以及对所述少模光纤返回的不同模式的光进行去模式处理后，发送至各自对应的所述波分解复用器；
    所述波分解复用器，还用于将接收到的模式对应的去模式处理后的返回的光发送给对应的第二光时域反射仪；
    所述第二光时域反射仪，还用于根据所述去模式处理后的返回的光，确定所述少模光纤中对应的模式在另一方向的性能。
  17. 如权利要求1至16任一项所述的系统，其特征在于，所述返回的光中包含所述测量光在所述光纤中传输时的瑞利散射光或布里渊散射光。
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