CN114938241B - Space mode multiplexing few-mode optical time domain reflectometer and implementation method thereof - Google Patents
Space mode multiplexing few-mode optical time domain reflectometer and implementation method thereof Download PDFInfo
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Abstract
The invention provides a space mode multiplexing few-mode optical time domain reflectometer which comprises a parameter adjustable light pulse output module, a space mode excitation module, a space mode separation module, a multi-path space mode synchronous detection module and a multi-path space mode back Rayleigh scattering signal processing and synthesizing module. The parameter-adjustable light pulse output module generates light pulses with adjustable parameters, the light pulses are excited by the spatial mode excitation module and injected onto the tested few-mode optical fiber link, the back Rayleigh scattering signals are extracted by the spatial mode separation module to be separated, and the back Rayleigh scattering signals are sent to the multi-channel spatial mode back Rayleigh scattering signal processing and synthesizing module to obtain a loss distribution curve of the tested few-mode optical fiber link after synchronous detection by the multi-channel spatial mode synchronous detection module, so that the type of fault event and the loss are determined. By implementing the method, the frequency of measurement is increased rapidly through spatial mode multiplexing, the noise of a detection curve is reduced more rapidly, the signal-to-noise ratio of a high-order spatial mode is optimized, and the dynamic range of measurement is improved.
Description
Technical Field
The invention relates to the technical field of optical fiber fault detection, in particular to a space mode multiplexing few-mode optical time domain reflectometer and an implementation method thereof.
Background
With the increasing number of communication services, the demand of people for transmission capacity of communication systems is increasing, and various new technologies are continuously emerging. Currently, a new generation of few-mode fiber (FMF) communication technology based on mode division multiplexing (Mode Division Multiplexing, MDM) is favored. The technology utilizes the limited orthogonal mode in the few-mode optical fiber as an independent channel for information transmission, can doubly improve the transmission capacity of the system, breaks through the capacity limit of the traditional single-mode optical fiber system, and becomes the most competitive expansion scheme for realizing Tbit/s and even Pbit/s transmission capacity of low-delay large-bandwidth 5G networks, access networks, data centers and the like. In recent years, the technology of mode division multiplexing communication is rapidly developed, so that the optical fiber communication is on the rise of a new step in the fields of super large capacity, super long distance and super high speed. Therefore, the method is in face of rapid development of few-mode optical fiber research and development, network construction and application, ensures reliable and efficient operation of long-distance large-capacity few-mode optical fiber links, has great significance in researching novel few-mode optical fiber link fault detection technology, and has wide development prospect.
At present, the fault detection of the few-mode Optical fiber link mainly continues the fault detection thought of the traditional single-mode Optical fiber, and mainly realizes the self-adaptive measurement of different dynamic ranges and spatial resolutions by adjusting the pulse width and peak power of the detection light through a single-mode Optical time-domain reflectometer (OTDR). The fault detection of the long-distance few-mode optical fiber link is realized by adopting a large pulse width, and the fault positioning with high precision is realized by adopting a narrow pulse width. However, for few-mode optical fiber links, each spatial mode has a larger loss than a single-mode optical fiber and a smaller non-excited coupling mode power, resulting in a smaller measurement signal-to-noise ratio, resulting in a smaller dynamic range under the same pulse parameters. Therefore, in order to achieve the same measurement dynamic range as that of the single-mode optical time domain reflectometer, the dynamic range of measurement needs to be increased by increasing pulse width, which tends to cause excessive power injected into the measured few-mode optical fiber to generate nonlinear effects, thereby affecting the measurement result. Meanwhile, considering the limitation of the normal operation of the line on the pulse power, for the few-mode optical time domain reflectometer, the actual requirement of the few-mode optical reflectometer for multi-scene measurement cannot be met only by adjusting the optical pulse width, namely the peak power, namely the long-distance few-mode optical fiber link is measured, the measurement time is long, the instantaneity is poor, the average times are more particularly in high-precision measurement, and the measurement time is longer. Therefore, how to effectively increase the dynamic range of the few-mode optical time domain reflectometer, increase the signal-to-noise ratio of the non-excited coupling mode and improve the measurement speed is an important content of the few-mode optical time domain reflectometer.
In the prior art, the few-mode optical time domain reflectometer adopts the following methods to improve the dynamic range, reduce noise and improve the fault detection speed, and specifically comprises the following steps: (1) A mode of increasing the optical pulse width and peak power, but the mode can lead to the limitation of the stimulated brillouin scattering nonlinear effect of the few-mode optical fiber, and the dynamic range of the mode is limited; (2) Though the dynamic range can be improved by adopting a pulse coding mode, the complexity of processing the digital signal of the system is improved, and the real-time performance of the system is poor.
Therefore, it is necessary to provide a new few-mode optical time domain reflectometer, which can realize real-time efficient, low-cost, high dynamic range and high spatial resolution fault detection and positioning of the few-mode optical fiber link.
Disclosure of Invention
The technical problem to be solved by the embodiment of the invention is to provide a space mode multiplexing few-mode optical time domain reflectometer and an implementation method thereof, wherein the frequency of measurement is increased rapidly through space mode multiplexing, so that the noise of a detection curve can be reduced more rapidly, the signal-to-noise ratio of a high-order space mode is optimized, the dynamic range of measurement is improved, and therefore, the fault detection and positioning of a few-mode optical fiber link with real time, high efficiency, low cost, high dynamic range and high spatial resolution can be realized.
In order to solve the technical problems, the embodiment of the invention provides a spatial mode multiplexing few-mode optical time domain reflectometer which is used on a tested few-mode optical fiber link and comprises a parameter adjustable optical pulse output module, a spatial mode excitation module, a spatial mode separation module, a multipath spatial mode synchronous detection module and a multipath spatial mode back Rayleigh scattering signal processing and synthesizing module which are connected in sequence;
the parameter adjustable light pulse output module is used for generating light pulses with specific parameters of repetition frequency, peak power and pulse width;
the spatial mode excitation module is used for exciting a fundamental mode LP carrying the light pulse 01 Mode conversion to fundamental mode LP 01 A mode and a high-order space mode, and injecting the mode and the high-order space mode into the tested few-mode optical fiber link;
the space mode separation module is used for extracting a back Rayleigh scattering signal generated on the tested few-mode optical fiber link, separating the back Rayleigh scattering signal and outputting a multi-route fundamental mode LP 01 A mode-borne back rayleigh scattering signal;
the multi-path space mode synchronous detection module is used for detecting multi-path route basic modes LP 01 Synchronously detecting the mode-carried back Rayleigh scattering signals to obtain multi-path space mode back Rayleigh scattering electric signals;
the multi-path space mode back Rayleigh scattering signal processing and synthesizing module is used for carrying out digital signal processing and synthesizing on the multi-path space mode back Rayleigh scattering signals to obtain a loss distribution curve of the tested few-mode optical fiber link, and determining the fault event type and the loss of the tested few-mode optical fiber link according to the loss distribution curve.
The parameter adjustable light pulse output module consists of a single-frequency light source, an electro-optic modulator, a signal generator and an optical fiber amplifier; wherein the light pulses are generated by a light source via an electro-optical modulator driven by the signal generator.
The light pulse is a pulse light source with the pulse width of 200ns, the peak power of 40mw and the repetition frequency of 2 kHz.
The embodiment of the invention also provides a method for realizing the space mode multiplexing few-mode optical time domain reflectometer, which is realized on the space mode multiplexing few-mode optical time domain reflectometer, and comprises the following steps:
generating light pulses with specific parameters of repetition frequency, peak power and pulse width;
the fundamental mode LP that will carry the light pulses 01 Mode conversion to fundamental mode LP 01 A mode and a high-order space mode, and is injected into a tested few-mode optical fiber link;
extracting a back Rayleigh scattering signal generated on the tested few-mode optical fiber link, separating the back Rayleigh scattering signal, and outputting a multi-route fundamental mode LP 01 A mode-borne back rayleigh scattering signal;
multi-route fundamental mode LP 01 Synchronously detecting the mode-carried back Rayleigh scattering signals to obtain multi-path space mode back Rayleigh scattering electric signals;
and carrying out digital signal processing synthesis on the multipath space mode back Rayleigh scattering signals to obtain a loss distribution curve of the tested few-mode optical fiber link, and further determining the fault event type and the loss of the tested few-mode optical fiber link according to the loss distribution curve.
Wherein said fundamental mode LP, which is to carry said light pulses 01 Mode conversion to fundamental mode LP 01 The specific steps of the mode and the high-order space mode and injecting the mode and the high-order space mode into the tested few-mode optical fiber link are,
passing the single-mode tail fiber carrying the optical pulse through a few-mode fiber circulator endThe few-die tail fiber is subjected to eccentric welding to excite a fundamental mode LP 01 And the mode and the high-order space mode are injected into the tested few-mode optical fiber link by a few-mode optical fiber circulator.
Wherein said splitting of said back rayleigh scatter signals is achieved by a mode multiplexer photon lantern.
The specific steps of obtaining the loss distribution curve of the tested few-mode optical fiber link include:
photoelectric detection and amplification are carried out on the multipath space mode back Rayleigh scattering signals;
sampling the multipath space mode back Rayleigh scattering signals after detection and amplification, and obtaining each path of space mode through digital signal processing;
and after amplitude compensation, time sequence adjustment alignment, spatial mode signal power superposition and averaging are carried out on each path of spatial mode, all spatial mode signals are synthesized, so that a loss distribution curve of the tested few-mode optical fiber link is obtained.
Wherein the light pulse is a pulse light source with the pulse width of 200ns, the peak power of 40mw and the repetition frequency of 2kHz
The embodiment of the invention has the following beneficial effects:
compared with the traditional single-mode optical time domain reflectometer technology, the invention uses multiplexing of multiple spatial modes, can efficiently improve the detection times and the number of measurement samples, increases the average measurement times, reduces noise power, improves the low signal-to-noise ratio of the high-order spatial mode, improves the dynamic range, effectively improves the measurement speed, combines the high sensitivity characteristic of the high-order spatial mode to fault loss, and improves the fault detection precision.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are required in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the invention, and that it is within the scope of the invention to one skilled in the art to obtain other drawings from these drawings without inventive faculty.
Fig. 1 is a schematic structural diagram of a spatial mode multiplexing few-mode optical time domain reflectometer according to an embodiment of the present invention;
fig. 2 is an application scenario diagram of a spatial mode multiplexing few-mode optical time domain reflectometer according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a multi-path spatial mode backward rayleigh scattering signal generated by optical pulse detection in an application scenario of a spatial mode multiplexing few-mode optical time domain reflectometer according to an embodiment of the present invention;
FIG. 4 is a graph of the detection of the multipath spatial mode reverse Rayleigh signal of FIG. 3 by amplitude compensation and superposition averaging;
fig. 5 is a flowchart of a spatial mode multiplexing few-mode optical time domain reflection method according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings, for the purpose of making the objects, technical solutions and advantages of the present invention more apparent.
As shown in fig. 1, in the embodiment of the present invention, a spatial mode multiplexing few-mode optical time domain reflectometer is provided, which is used on a measured few-mode optical fiber link, and includes a parameter adjustable optical pulse output module 200, a spatial mode excitation module 201, a spatial mode separation module 202, a multi-channel spatial mode synchronous detection module 203, and a multi-channel spatial mode backward rayleigh scattering signal processing synthesis module 204 that are sequentially connected;
the parameter adjustable light pulse output module 200 is used for generating light pulses with specific parameters of repetition frequency, peak power and pulse width; the parameter adjustable light pulse output module 200 is composed of a single-frequency light source, an electro-optic modulator, a signal generator and an optical fiber amplifier, and the light pulse is generated by the light source through the electro-optic modulator driven by the signal generator; in one example, the light pulse is a pulse light source with a pulse width of 200ns, a peak power of 40mw and a repetition frequency of 2 kHz; it can be appreciated that the pulse width, peak power and repetition frequency of the light pulses can be adjusted according to actual requirements;
a spatial mode excitation module 201 for exciting a fundamental mode LP carrying light pulses 01 Mode conversion to fundamental mode LP 01 Mode and higher order spatial mode LP i And injecting the small-mode fiber on the tested few-mode fiber link; in one example, a single mode pigtail carrying an optical pulse is excited into a fundamental mode LP by fusion-splicing with a few-mode pigtail at a few-mode fiber circulator port 01 Mode and higher order spatial mode LP i Injecting the measured few-mode optical fiber link by the few-mode optical fiber circulator;
the spatial mode separation module 202 is configured to extract a back rayleigh scattering signal generated on the detected few-mode optical fiber link, separate the back rayleigh scattering signal, and output a multi-route fundamental mode LP 01 A mode-borne back rayleigh scattering signal; in one example, the backward Rayleigh scattering signal generated on the tested few-mode optical fiber link is separated by a mode multiplexer photon lantern, and is represented by a high-order spatial mode LP i Conversion to fundamental mode LP 01 Mode, thereby obtaining a multi-route fundamental mode LP 01 A mode-borne back rayleigh scattering signal;
a multipath space mode synchronous detection module 203 for multiplexing the fundamental mode LP 01 Synchronously detecting the mode-carried back Rayleigh scattering signals to obtain multi-path space mode back Rayleigh scattering electric signals; in one example, the multi-route fundamental mode LP 01 Photoelectric detection is carried out on the mode-carried back Rayleigh scattering signal, and the mode-carried back Rayleigh scattering signal is converted into a corresponding back Rayleigh scattering electric signal which is used as a fundamental mode LP 01 Mode and higher order spatial mode LP i Back rayleigh scattering signals;
the multi-channel space mode back Rayleigh scattering signal processing and synthesizing module 204 is configured to perform digital signal processing and synthesizing on multi-channel space mode back Rayleigh scattering signals to obtain a loss distribution curve of the tested few-mode optical fiber link, and further determine a fault event type and a loss size of the tested few-mode optical fiber link according to the loss distribution curve. In one example, for the fundamental mode LP 01 Mode and higher order spatial mode LP i Data acquisition and different spatial mode amplitude by back Rayleigh scattering signalsValue compensation, time sequence adjustment alignment, spatial mode signal power superposition and average to obtain a measured few-mode optical fiber link loss distribution curve and realize the detection of few-mode optical fiber link faults
As shown in fig. 2 to fig. 4, an application scenario of the spatial mode multiplexing few-mode optical time domain reflectometer provided in the embodiment of the present invention is further described, which specifically includes:
in fig. 2, a single-frequency laser DFB-LD 1 outputs a single-frequency continuous detection light source, enters an electro-optical modulator EOM 2, generates detection light pulses with adjustable frequency and pulse width under the drive of a signal generator SG 3, and the detection light pulses output by the electro-optical modulator EOM 2 are amplified by an erbium-doped fiber amplifier EDFA4 and then injected into a few-mode fiber circulator 6, wherein the EDFA outputs a single-mode tail fiber and a few-mode tail fiber at an a port of the few-mode fiber circulator are subjected to eccentric fusion 5, so that excitation of a high-order space mode is realized; by utilizing the unidirectional transmission characteristics of the few-mode fiber circulator 6, the few-mode fiber circulator 6 is injected from port a and output from port B into the tested few-mode fiber links 9, 10 and 11 via connector (APC/PC interface) 7, wherein the fault type 10 is typically a fusion fault, connector mismatch, bending, etc. The backward Rayleigh scattered light generated in the few-mode optical fibers 9, 10 and 11 to be detected returns through the port B of the few-mode optical fiber circulator 6 and is output from the port C, then enters the spatial mode demultiplexer photon lantern PL 12 to carry out multi-path mixed spatial mode separation, and the few-mode tail fiber at the port C of the few-mode optical fiber circulator 6 and the few-mode tail fiber of the photon lantern PL 12 are welded in the center. And each path of space mode output by the photon lantern PL 12 respectively enters the photoelectric detection PD 13 to carry out photoelectric conversion, and a multipath space mode back Rayleigh scattering electric signal is output. And the data is acquired by the data acquisition ADC 14, and finally the digital signal processing 15 is carried out, and the processes of different spatial mode amplitude compensation, time sequence adjustment alignment, spatial mode signal power superposition and average digital signal processing are carried out, so that all the spatial mode signals are synthesized, and a final fault detection result is obtained.
In FIG. 3, the LP is a typical test result of probe pulse generation with a pulse width of 200ns, a peak power of 40mw, and a repetition frequency of 2kHz 01 、LP 11a 、LP 11b 、LP 21a 、LP 21b LP (Low-pressure-sensitive fragment) 02 The 6 space mode back Rayleigh scattering signals are respectively subjected to amplitude compensation, time sequence adjustment alignment, space mode signal power synthesis and average to obtain a final test result.
In fig. 4, the distribution curves of the loss of the few-mode fiber back rayleigh scattering after synthesizing all the spatial mode signals are obtained by compensating the amplitude of different spatial modes, adjusting and aligning the time sequence, superposing and averaging the power of the spatial mode signals, and the fault is a fusion fault through analysis.
Therefore, compared with single-mode optical fiber OTDR, the spatial mode multiplexing scheme adopted by the embodiment of the invention can effectively improve the detection times and the number of measurement samples, effectively improve the measurement speed, has smaller fading noise and improves the dynamic range. Meanwhile, the scheme combines the high sensitivity characteristic of the high-order space mode to the fault loss, and has higher fault detection and positioning precision compared with the traditional single-mode OTDR.
As shown in fig. 5, in an embodiment of the present invention, a method for implementing a spatial mode multiplexing few-mode optical time domain reflectometer is provided, which is implemented on the foregoing spatial mode multiplexing few-mode optical time domain reflectometer, and the method includes the following steps:
step S1, generating light pulses with specific parameters of repetition frequency, peak power and pulse width;
step S2, the fundamental mode LP carrying the light pulses 01 Mode conversion to fundamental mode LP 01 A mode and a high-order space mode, and is injected into a tested few-mode optical fiber link;
s3, extracting a back Rayleigh scattering signal generated on the tested few-mode optical fiber link, separating the back Rayleigh scattering signal, and outputting a multi-route fundamental mode LP 01 A mode-borne back rayleigh scattering signal;
step S4, the multi-route basic mode LP 01 Synchronously detecting the mode-carried back Rayleigh scattering signals to obtain multi-path space mode back Rayleigh scattering electric signals;
and S5, carrying out digital signal processing synthesis on the multipath space mode back Rayleigh scattering signals to obtain a loss distribution curve of the tested few-mode optical fiber link, and further determining the fault event type and the loss of the tested few-mode optical fiber link according to the loss distribution curve.
Wherein said fundamental mode LP, which is to carry said light pulses 01 Mode conversion to fundamental mode LP 01 The specific steps of the mode and the high-order space mode and injecting the mode and the high-order space mode into the tested few-mode optical fiber link are,
the single-mode tail fiber bearing the optical pulse is subjected to eccentric welding with the few-mode tail fiber at the port of the few-mode fiber circulator, and a fundamental mode LP is excited 01 And the mode and the high-order space mode are injected into the tested few-mode optical fiber link by a few-mode optical fiber circulator.
Wherein said splitting of said back rayleigh scatter signals is achieved by a mode multiplexer photon lantern.
The specific steps of obtaining the loss distribution curve of the tested few-mode optical fiber link include:
photoelectric detection and amplification are carried out on the multipath space mode back Rayleigh scattering signals;
sampling the multipath space mode back Rayleigh scattering signals after detection and amplification, and obtaining each path of space mode through digital signal processing;
and after amplitude compensation, time sequence adjustment alignment, spatial mode signal power superposition and averaging are carried out on each path of spatial mode, all spatial mode signals are synthesized, so that a loss distribution curve of the tested few-mode optical fiber link is obtained.
Wherein the light pulse is a pulse light source with the pulse width of 200ns, the peak power of 40mw and the repetition frequency of 2kHz
The embodiment of the invention has the following beneficial effects:
compared with the traditional single-mode optical time domain reflectometer technology, the invention uses multiplexing of multiple spatial modes, can efficiently improve the detection times and the number of measurement samples, increases the average measurement times, reduces noise power, improves the low signal-to-noise ratio of the high-order spatial mode, improves the dynamic range, effectively improves the measurement speed, combines the high sensitivity characteristic of the high-order spatial mode to fault loss, and improves the fault detection precision.
Those of ordinary skill in the art will appreciate that all or a portion of the steps in implementing the methods of the above embodiments may be implemented by a program to instruct related hardware, where the program may be stored in a computer readable storage medium, such as ROM/RAM, a magnetic disk, an optical disk, etc.
The foregoing disclosure is illustrative of the present invention and is not to be construed as limiting the scope of the invention, which is defined by the appended claims.
Claims (8)
1. The spatial mode multiplexing few-mode optical time domain reflectometer is used for a measured few-mode optical fiber link and is characterized by comprising a parameter adjustable optical pulse output module, a spatial mode excitation module, a spatial mode separation module, a multipath spatial mode synchronous detection module and a multipath spatial mode backward Rayleigh scattering signal processing and synthesizing module which are connected in sequence;
the parameter adjustable light pulse output module is used for generating light pulses with specific parameters of repetition frequency, peak power and pulse width;
the spatial mode excitation module is used for exciting a fundamental mode LP carrying the light pulse 01 Mode conversion to fundamental mode LP 01 A mode and a high-order space mode, and injecting the mode and the high-order space mode into the tested few-mode optical fiber link;
the space mode separation module is used for extracting a back Rayleigh scattering signal generated on the tested few-mode optical fiber link, separating the back Rayleigh scattering signal and outputting a multi-route fundamental mode LP 01 A mode-borne back rayleigh scattering signal;
the multi-path space mode synchronous detection module is used for detecting multi-path route basic modes LP 01 Synchronously detecting the mode-carried back Rayleigh scattering signals to obtain multi-path space mode back Rayleigh scattering electric signals;
the multi-path space mode back Rayleigh scattering signal processing and synthesizing module is used for carrying out digital signal processing and synthesizing on the multi-path space mode back Rayleigh scattering signals to obtain a loss distribution curve of the tested few-mode optical fiber link, and determining the fault event type and the loss of the tested few-mode optical fiber link according to the loss distribution curve.
2. The spatial mode multiplexing few-mode optical time domain reflectometer according to claim 1, wherein the parameter adjustable optical pulse output module is composed of a single-frequency light source, an electro-optical modulator, a signal generator and an optical fiber amplifier; wherein the light pulses are generated by a light source via an electro-optical modulator driven by the signal generator.
3. The spatial mode multiplexed few-mode optical time domain reflectometer according to claim 2, wherein the optical pulse is a pulsed optical source with a pulse width of 200ns, a peak power of 40mw, and a repetition frequency of 2 kHz.
4. A method for implementing a spatial mode multiplexing few-mode optical time domain reflectometer, characterized in that it is implemented on a spatial mode multiplexing few-mode optical time domain reflectometer as claimed in claim 3, said method comprising the steps of:
generating light pulses with specific parameters of repetition frequency, peak power and pulse width;
the fundamental mode LP that will carry the light pulses 01 Mode conversion to fundamental mode LP 01 A mode and a high-order space mode, and is injected into a tested few-mode optical fiber link;
extracting a back Rayleigh scattering signal generated on the tested few-mode optical fiber link, separating the back Rayleigh scattering signal, and outputting a multi-route fundamental mode LP 01 A mode-borne back rayleigh scattering signal;
multi-route fundamental mode LP 01 Synchronously detecting the mode-carried back Rayleigh scattering signals to obtain multi-path space mode back Rayleigh scattering electric signals;
and carrying out digital signal processing synthesis on the multipath space mode back Rayleigh scattering signals to obtain a loss distribution curve of the tested few-mode optical fiber link, and further determining the fault event type and the loss of the tested few-mode optical fiber link according to the loss distribution curve.
5. The method of implementing a spatial mode multiplexed few-mode optical time domain reflectometer according to claim 4, wherein the fundamental mode LP that will carry the optical pulse 01 Mode conversion to fundamental mode LP 01 The specific steps of the mode and the high-order space mode and injecting the mode and the high-order space mode into the tested few-mode optical fiber link are,
the single-mode tail fiber bearing the optical pulse is subjected to eccentric welding with the few-mode tail fiber at the port of the few-mode fiber circulator, and a fundamental mode LP is excited 01 And the mode and the high-order space mode are injected into the tested few-mode optical fiber link by a few-mode optical fiber circulator.
6. The method of spatial mode multiplexed few-mode optical time domain reflectometry according to claim 4, wherein said separating said back rayleigh scattering signal is accomplished by a mode multiplexer photon lantern.
7. The method for implementing the spatial mode multiplexing few-mode optical time domain reflectometer according to claim 4, wherein the specific step of performing digital signal processing synthesis on the multipath spatial mode back-to-rayleigh scattering signals to obtain the loss distribution curve of the measured few-mode optical fiber link comprises the following steps:
photoelectric detection and amplification are carried out on the multipath space mode back Rayleigh scattering signals;
sampling the multipath space mode back Rayleigh scattering signals after detection and amplification, and obtaining each path of space mode through digital signal processing;
and after amplitude compensation, time sequence adjustment alignment, spatial mode signal power superposition and averaging are carried out on each path of spatial mode, all spatial mode signals are synthesized, so that a loss distribution curve of the tested few-mode optical fiber link is obtained.
8. The method for implementing the spatial mode multiplexing few-mode optical time domain reflectometer according to claim 4, wherein the optical pulse is a pulse light source with a pulse width of 200ns, a peak power of 40mw and a repetition frequency of 2 kHz.
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| US10018558B2 (en) * | 2016-08-22 | 2018-07-10 | Nec Corporation | Distributed acoustic sensing in a multicore optical fiber using distributed mode coupling, delay, and simultaneous pulsing with selectable spatial modes |
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| CN110071762A (en) * | 2019-04-30 | 2019-07-30 | 吉林大学 | A kind of less fundamental mode optical fibre fault detection method based on higher order mode back rayleigh scattering |
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