CN110375960B - Device and method based on super-continuum spectrum light source OTDR - Google Patents
Device and method based on super-continuum spectrum light source OTDR Download PDFInfo
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Abstract
本发明是一种基于超连续谱光源OTDR的装置及方法。本发明主要用于解决传统OTDR空间分辨率与动态范围无法同时提高的问题。本发明采用超连续谱光源，光谱范围宽至几百nm，比传统激光器拥有更宽的光谱范围；经过可协调光滤波器产生波长可调激光信号，使得其空间分辨率达到毫米量级。超连续谱光源输出稳定，输出功率大，动态范围大，且不影响系统空间分辨率，其能量能够持续性输出，且具有高的信噪比。所述装置，包括锁模激光器、两个偏振控制器、高速电光调制器、微波信号源、脉冲光放大器、高非线性光纤、两个可调谐光滤波器、光隔离器、1×2光纤耦合器、光环行器、待测光纤、可变光延迟线、两个光电探测器、光放大器、示波器、计算机。
The present invention is a device and method based on a supercontinuum light source OTDR. The invention is mainly used to solve the problem that the traditional OTDR spatial resolution and dynamic range cannot be improved at the same time. The invention adopts a supercontinuum light source, the spectral range is as wide as several hundred nm, and has a wider spectral range than the traditional laser; the wavelength-tunable laser signal is generated through a coordinated optical filter, so that its spatial resolution reaches the order of millimeters. The supercontinuum light source has stable output, large output power, large dynamic range, and does not affect the spatial resolution of the system. Its energy can be continuously output, and it has a high signal-to-noise ratio. The device includes a mode-locked laser, two polarization controllers, a high-speed electro-optical modulator, a microwave signal source, a pulsed optical amplifier, a highly nonlinear optical fiber, two tunable optical filters, an optical isolator, and a 1×2 fiber coupling device, optical circulator, optical fiber to be measured, variable optical delay line, two photodetectors, optical amplifier, oscilloscope, computer.
Description
Technical Field
The invention is applied to the field of distributed optical fiber sensing detection, in particular to a device and a method based on an OTDR (optical time Domain reflectometer) of a supercontinuum light source, which can realize the real-time measurement of long-distance high resolution of optical fiber faults.
Background
OTDR testing in a distributed fiber sensing system based on an OTDR rayleigh scattering system is typically analyzed by launching optical pulses into the fiber and then receiving the returned information at the OTDR port. When light pulses are transmitted within an optical fiber, scattering and reflection may occur due to the nature of the fiber itself, connectors, splices, bends, or other similar events. Some of the scattered and reflected signals are returned to the OTDR and the device determines the state of the fiber by measuring and processing the scattered and reflected signals.
The OTDR is a main instrument for detecting optical cable lines at present, and the characteristics of optical fibers are detected by utilizing backward Rayleigh scattering and Fresnel reflection in the optical fibers; OTDR increasingly shows its superiority in measurement accuracy, measurement range and measurement speed with its integration. With the rapid development of distributed optical fibers, OTDR-based distributed optical fiber sensors will still be a hot spot for research, and especially, new distributed optical fiber sensors based on OTDR will be an important development direction.
The OTDR technique generally requires a larger dynamic range for the measurement of the optical fiber link at the insertion section, and the conventional OTDR technique has problems of limited input power, limited detection distance, and low spatial resolution, and thus a novel OTDR device and technique are urgently needed to be invented. In order to obtain high spatial resolution in OTDR, the pulse width of the laser needs to be narrowed. Further, if the pulse width of the laser beam is narrowed, the power of the laser beam needs to be increased to compensate for the decrease in the measured signal-to-noise ratio due to the decrease in the energy of the laser beam. But this may cause a decrease in measurement performance or interference with a communication signal due to a nonlinear optical phenomenon such as stimulated brillouin scattering occurring in the optical line. Therefore, in OTDR, the spatial resolution is limited to around several meters.
An optical time domain reflection testing device and a measuring method thereof (application number CN 200810240937) of semiconductor institute of Chinese academy provide an optical time domain reflection testing device, the method divides coded optical pulse signals composed of two optical pulses with different wavelengths into detection optical signals and reference optical signals, the detection optical signals generate reflected optical signals when encountering optical fiber breakpoints or damage points after entering an optical fiber link to be tested, the reflected optical signals and the reference optical signals enter a photoelectric detector together for beat frequency, and the beat frequency signals enter a beat frequency signal detecting device for observation and recording; the two light pulses are time separated by T1 and the spectrum of the corresponding beat signal is observed and recorded. Although this device uses two pulse signals to greatly increase the dynamic range of the fiber, it also increases the cost of the device, and the increase in spatial resolution is limited to the difference between the two pulse widths.
An optical time domain reflectometry apparatus and method of the forty first institute of research of the company of electronic science and technology in china (application number CN 201310187847). A pulse signal generator in the optical time domain reflection measuring device generates an excitation pulse signal, signal light output by a pulse light source obtains proper optical power through an attenuator, output light of the attenuator is injected into a measured optical fiber through an optical directional coupler, and Fresnel reflection and backward scattering light returned from the measured optical fiber enter a high-speed optical sampler through the optical directional coupler. The invention solves the problem that the OTDR has a large dynamic photoelectric signal receiving blind area, but the space resolution of the pulse light source used by the light source is still limited.
In order to overcome the defect that the resolution and dynamic range of the pulse type OTDR can not be simultaneously improved, scientific researchers utilize
The pseudo-random code generator modulates the pulse laser signal, and improves the dynamic range and the spatial resolution of the system to a certain extent (EP 0269448); however, pseudo-random codes have the disadvantage of generating only a limited code length, which causes adjacent codes to overlap, so that the spatial resolution of the measurement is typically on the order of meters, and the measurement accuracy depends mainly on the coding rate and the modulation rate.
Due to the limitation of pseudo-random codes, a chaotic light time domain reflection technology (CN 200810054534) is proposed, which mainly uses chaotic light as detection light of a system, and chaotic laser has the characteristics of initial value sensitivity, ergodicity, short coherence length, wide bandwidth, strong anti-interference performance and the like. Due to the wide bandwidth of the chaotic laser, the resolution and dynamic range of OTDR can be significantly improved (IEEE Photonics Technology Letters, 2008, 20 (19): 1636-. However, in the current chaotic OTDR technique, the chaotic laser is composed of a semiconductor laser by optical feedback, the laser relaxation oscillation is obvious, the bandwidth is limited, and the spatial resolution that the chaotic laser can achieve is 2cm (Journal of Lightwave Technology, 2012, 30(21): 3420-.
The general OTDR is limited in dynamic range and spatial resolution, and particularly has the problem of bottleneck of a large dynamic photoelectric signal receiving blind area which cannot be overcome; coherent OTDR adopts coherent reception of optical pulses, and can improve the sensitivity of a receiver under the condition of not improving pulse power, thereby improving the dynamic range and the signal-to-noise ratio of the OTDR, but the coherent detection has high requirements on the stability of light source frequency and lower distance resolution. The device and the method based on the super-continuum spectrum light source OTDR of the invention use the super-continuum spectrum light source, have ultra-wide spectrum, short coherence length and two to three orders of magnitude larger output power than the traditional laser, effectively solve the problems of limited input power, limited detection distance and low spatial resolution of the traditional OTDR technology at present and solve the problem that the resolution and the dynamic resolution range of the traditional optical time domain reflectometer can not be simultaneously improved. The device can be used for accurately measuring the spatial resolution to millimeter level without the limitation of detection bandwidth, and the signal-to-noise ratio is improved.
Disclosure of Invention
The invention provides a device and a method based on an OTDR (optical time domain reflectometer) of a supercontinuum light source, which realize monitoring by replacing an optical pulse signal with the supercontinuum. The resolution and the dynamic resolution range are simultaneously improved, and the stable work of the system is achieved.
An apparatus based on a supercontinuum light source OTDR, characterized in that: the device comprises a mode-locked laser, a first polarization controller, a high-speed electro-optic modulator, a microwave signal source, a second polarization controller, a pulse optical amplifier, a high-nonlinearity optical fiber, a first tunable optical filter, an optical isolator, a 1 x 2 optical fiber coupler, an optical circulator, an optical fiber to be tested, a variable optical delay line, a first photoelectric detector, an optical amplifier, a second tunable optical filter, a second photoelectric detector, an oscilloscope and a computer;
the exit end of the mode-locked laser is connected with the incident end of the first polarization controller; the emergent end of the first polarization controller is connected with the incident end of the high-speed electro-optic modulator through a single-mode optical fiber jumper; the emergent end of the high-speed electro-optic modulator is connected with the incident end of the second polarization controller through a single-mode optical fiber jumper; the signal output end of the microwave signal source is connected with the radio frequency input end of the high-speed electro-optical modulator through a high-frequency coaxial cable; the second polarization controller is connected with the incident end of the pulse light amplifier through a single-mode optical fiber jumper; the exit end of the pulse light amplifier is connected with the incident end of the high nonlinear optical fiber through a single mode optical fiber jumper; the exit end of the high nonlinear optical fiber is connected with the incident end of the first tunable optical filter through a single mode optical fiber jumper; the exit end of the first tunable optical filter is connected with the entrance end of the optical isolator through a single-mode optical fiber jumper; the emergent end of the optical isolator is connected with the incident end of the 1 multiplied by 2 optical fiber coupler through a single mode optical fiber jumper;
the first emergent end of the 1 multiplied by 2 optical fiber coupler is connected with the incident end of the optical circulator through a single-mode optical fiber jumper; the reflection end of the optical circulator is connected with the incidence end of the optical fiber to be tested; the exit end of the optical circulator is connected with the entrance end of the optical amplifier through a single-mode optical fiber jumper; the exit end of the optical amplifier is connected with the entrance end of the second tunable optical filter; the exit end of the second tunable optical filter is connected with the incident end of the second photoelectric detector through a single-mode optical fiber jumper; the emergent end of the second photoelectric detector is connected with the first signal input end of the oscilloscope through a single-mode optical fiber jumper;
the second emergent end of the 1 multiplied by 2 optical fiber coupler is connected with the incident end of the variable optical delay line through a single mode optical fiber jumper; the exit end of the variable optical delay line is connected with the incident end of the first photoelectric detector through a single-mode optical fiber jumper; the emergent end of the first photoelectric detector is connected with a second signal incident end of the oscilloscope; the exit end of the oscilloscope is connected with the signal entrance end of the computer.
A method based on the OTDR of the supercontinuum light source, this method is realized in an OTDR apparatus based on supercontinuum light source, this method adopts the following steps to realize:
firstly, a mode-locked optical pulse signal output by a mode-locked laser is subjected to polarization state adjustment through a first polarization controller, and then a microwave signal source inputs the output sine wave signal into a high-speed electro-optical modulator as a modulation signal; mode-locking optical pulse and sine wave signal are input into the high-speed electro-optical modulator through the incident end and the radio frequency port of the high-speed electro-optical modulator, and the high-quality modulation of the sine radio frequency signal on the pulse signal can be realized by controlling the bias voltage of the microwave signal source; the signal continues to pass through a second polarization controller to adjust the polarization state and inject the output pulse into the high nonlinear optical fiber for transmission after the power of the pulse optical amplifier is amplified, and the output signal is not only influenced by various nonlinear effects such as self-phase modulation, cross-phase modulation, four-wave mixing, stimulated Raman scattering and the like, but also influenced by the dispersion property of the optical fiber; modulation instability effects caused by interaction between nonlinearity and dispersion can cause optical pulse spectrum broadening to generate a supercontinuum; the first tunable optical filter selects a proper filtering center and filtering bandwidth to filter the generated supercontinuum; the filtered signal enters a 1 multiplied by 2 optical fiber coupler and is divided into two paths after being isolated by an optical isolator; one path enters the optical fiber to be detected after being circulated by the optical circulator to generate back scattering; the output end of the optical circulator is connected with an optical amplifier to amplify the reflected signal, backward Rayleigh scattered light and Fresnel reflected light are filtered out by a second tunable optical filter, and the optical signal is converted into an electric signal by a second photoelectric detector and is input into an oscilloscope for collecting time sequence;
the other path of optical signal is used as a reference optical signal, the optical path of the reference light is adjusted through the variable optical delay line, and the zero point is calibrated; inputting the first photoelectric detector to an oscilloscope to acquire a time sequence; and finally, processing data by using a computer, and determining an optical fiber connection point, an optical fiber terminal or a breakpoint by calculating a correlation function between the reference light and the backward Rayleigh scattering signal.
Compared with the existing distributed optical fiber OTDR system, the device and the method based on the supercontinuum light source OTDR have the following advantages:
the supercontinuum light source used by the invention has ultrahigh spectral power density, smoother spectrum, ultralow intensity noise and shorter coherence length, so that the dynamic range and spatial resolution of positioning measurement are improved qualitatively; compared with the traditional light source, the device based on the OTDR is more stable; the optical fiber-based supercontinuum light source is simple in design, and can obtain broadband, transformation limit and space coherent light beams, so that the optical fiber-based supercontinuum light source is very suitable for application of an existing distributed optical fiber positioning system.
Second, although the optical time domain reflectometer of wavelength-coded optical time domain reflectometer and the measurement method thereof (application number CN 200810240937) has a large dynamic range and high resolution, the problem that the resolution and the dynamic resolution range of the conventional OTDR (optical time domain reflectometer) cannot be simultaneously improved is solved. However, the spatial resolution is still influenced by the light pulse width, and light pulses with two wavelengths are needed, so that the experiment cost is too high; the super-continuum spectrum light source used by the invention is easy to realize, simple in structure, convenient to operate, stable and sufficient in output power, and capable of reaching a measuring range of more than three hundred kilometers, and can be effectively used in actual engineering.
Thirdly, the common OTDR is limited in dynamic range and spatial resolution, and the bottleneck problem of a large dynamic photoelectric signal receiving blind area which cannot be overcome exists, but the invention adopts a super-continuum spectrum as a light source, the spatial resolution of a system is completely determined by the coherence length of the light source, the coherence length of the super-continuum spectrum is very short, and the spatial resolution can reach millimeter magnitude; effectively solve signal reception blind area problem.
Modulating the pulse laser signal by using a pseudo-random code generator, and improving the dynamic range and the spatial resolution of the system to a certain extent (EP 0269448); however, pseudo-random codes have the disadvantage of generating only a limited code length, which causes adjacent codes to overlap, so that the spatial resolution of the measurement is typically on the order of meters, and the measurement accuracy depends mainly on the coding rate and the modulation rate. The OTDR based on the supercontinuum light source has millimeter-scale spatial resolution, and is more favorable for high-precision monitoring.
Although the chaotic OTDR solves the problems of dynamic range and spatial resolution to a certain extent, the hybrid laser is formed by a semiconductor laser by optical feedback, the laser relaxation oscillation is obvious, the bandwidth is limited, and the spatial resolution which can be achieved by the chaotic laser is 2cm at present. The method can not precisely detect the long-distance fine cracks, so that the application aspect is limited to a certain extent. The super-continuum spectrum light source greatly improves the dynamic range and the spatial resolution of the system, and can completely monitor the problems.
Drawings
Fig. 1 is a schematic structural diagram of an apparatus and method based on an OTDR of a supercontinuum light source according to the present invention.
In the figure: the device comprises a 1-mode-locked laser, a 2-first polarization controller, a 3-high-speed electro-optical modulator, a 4-microwave signal source, a 5-second polarization controller, a 6-pulse optical amplifier, a 7-high nonlinear optical fiber, an 8-first tunable optical filter, a 9-optical isolator, a 10-1 x 2 optical fiber coupler, an 11-optical circulator, a 12-optical fiber to be tested, a 13-variable optical delay line, a 14-first photoelectric detector, a 15-optical amplifier, a 16-second tunable optical filter, a 17-second photoelectric detector, an 18-oscilloscope and a 19-computer.
Detailed Description
A device based on a supercontinuum light source OTDR (optical time domain reflectometer) comprises a mode-locked laser 1, a first polarization controller 2, a high-speed electro-optic modulator 3, a microwave signal source 4, a second polarization controller 5, a pulse light amplifier 6, a high-nonlinearity optical fiber 7, a first tunable optical filter 8, an optical isolator 9, a 1 x 2 optical fiber coupler 10, an optical circulator 11, an optical fiber 12 to be tested, a variable optical delay line 13, a first photoelectric detector 14, an optical amplifier 15, a second tunable optical filter 16, a second photoelectric detector 17, an oscilloscope 18 and a computer 19;
the exit end of the mode-locked laser 1 is connected with the incident end of the first polarization controller 2; the emergent end of the first polarization controller 2 is connected with the incident end of the high-speed electro-optic modulator 3 through a single-mode optical fiber jumper; the emergent end of the high-speed electro-optical modulator 3 is connected with the incident end of the second polarization controller 5 through a single-mode optical fiber jumper; the signal output end of the microwave signal source 4 is connected with the radio frequency input end of the high-speed electro-optical modulator 3 through a high-frequency coaxial cable; the second polarization controller 5 is connected with the incident end of the pulse light amplifier 6 through a single-mode optical fiber jumper; the emergent end of the pulse light amplifier 6 is connected with the incident end of the high nonlinear optical fiber 7 through a single mode optical fiber jumper; the emergent end of the high nonlinear optical fiber 7 is connected with the incident end of the first tunable optical filter 8 through a single-mode optical fiber jumper; the emergent end of the first tunable optical filter 8 is connected with the incident end of the optical isolator 9 through a single-mode optical fiber jumper; the emergent end of the optical isolator 9 is connected with the incident end of the 1 multiplied by 2 optical fiber coupler 10 through a single mode optical fiber jumper;
the first emergent end of the 1 × 2 optical fiber coupler 10 is connected with the incident end of the optical circulator 11 through a single-mode optical fiber jumper; the reflection end of the optical circulator 11 is connected with the incidence end of the optical fiber 12 to be tested; the exit end of the optical circulator 11 is connected with the entrance end of the optical amplifier 15 through a single-mode optical fiber jumper; the exit end of the optical amplifier 15 is connected with the entrance end of the second tunable optical filter 16; the exit end of the second tunable optical filter 16 is connected with the incident end of the second photoelectric detector 17 through a single-mode optical fiber jumper; the emergent end of the second photoelectric detector 17 is connected with the first signal input end of the oscilloscope 18 through a single-mode optical fiber jumper;
the second emergent end of the 1 × 2 optical fiber coupler 10 is connected with the incident end of the variable optical delay line 13 through a single-mode optical fiber jumper; the exit end of the variable optical delay line 13 is connected with the incident end of the first photodetector 14 through a single-mode optical fiber jumper; the emergent end of the first photoelectric detector 14 is connected with the second signal incident end of the oscilloscope 18; the exit end of the oscilloscope 18 is connected with the signal entrance end of the computer 19.
A method based on the OTDR of the supercontinuum light source, this method is realized in an OTDR apparatus based on supercontinuum light source, this method adopts the following steps to realize:
firstly, a mode-locked optical pulse signal output by a mode-locked laser 1 passes through a first polarization controller 2 to adjust the polarization state, and then a microwave signal source 4 inputs the output sine wave signal as a modulation signal into a high-speed electro-optical modulator 3; mode-locking optical pulse and sine wave signal are respectively input into the high-speed electro-optical modulator 3 through the incident end and the radio frequency port of the high-speed electro-optical modulator 3, and high-quality modulation of the sine radio frequency signal on the pulse signal can be realized by controlling the bias voltage of the microwave signal source 4; the signal continues to pass through the second polarization controller 5 to adjust the polarization state and inject the output pulse into the high nonlinear optical fiber 7 for transmission after the power amplification of the pulse optical amplifier 6, and the output signal is not only influenced by various nonlinear effects such as self-phase modulation, cross-phase modulation, four-wave mixing, stimulated Raman scattering and the like, but also influenced by the dispersion property of the optical fiber; modulation instability effects caused by interaction between nonlinearity and dispersion can cause optical pulse spectrum broadening to generate a supercontinuum; the first tunable optical filter 8 selects a proper filtering center and filtering bandwidth to filter the generated supercontinuum; the filtered signal enters a 1 multiplied by 2 optical fiber coupler 10 to be divided into two paths after being isolated by an optical isolator 9; one path enters the optical fiber 12 to be tested after being looped by the optical circulator 11 to generate back scattering; the output end of the optical circulator 11 is connected with an optical amplifier 15 to amplify the reflected signal, backward Rayleigh scattered light and Fresnel reflected light are filtered out by a second tunable optical filter 16, and the optical signal is converted into an electrical signal by a second photoelectric detector 17 and input into an oscilloscope 18 to acquire a time sequence;
the other path of optical signal is used as a reference optical signal, the optical path of the reference light is adjusted through the variable optical delay line 13, and the zero point is calibrated; then inputting the first photoelectric detector 14 to an oscilloscope 18 for collecting time sequence; finally, the data is processed by the computer 19, and the optical fiber connection point, the optical fiber terminal or the breakpoint can be determined by calculating the correlation function between the reference light and the backward Rayleigh scattering signal.
In specific implementation, the supercontinuum is composed of a mode-locked pulse laser 1 (MLL, Pritel, UOC-05-14G-E), a first polarization controller 2, a microwave signal source 4 (Model-SNP 1012-520-01), a high-speed electro-optic modulator 3 (EOM, photonic, MXAN-LN-10), a second polarization controller 5, a pulse optical amplifier 6 and a high nonlinear optical fiber 7; the super-continuum spectrum generates a spectrum with a width of 1400nm to 1680nm, a wavelength and bandwidth tunable optical signal is generated through a first tunable optical filter 8, and the model of the first tunable optical filter 8 is XTM-50; the coupling ratio of the 1 multiplied by 2 optical fiber coupler 10 is 99: 1; the variable optical delay line 13 adopts an MDL-002 type electrically controlled variable optical delay line. The optical amplifier 15 is an erbium-doped fiber amplifier or a semiconductor optical amplifier. The first photodetector 14 and the second photodetector 17 employ a Newport 1544-B type photodetector. The optical fiber 12 to be measured adopts G655 or G652 series single-mode optical fiber, and the length of the single-mode optical fiber is 300 km.
Claims (2)
1. An apparatus based on a supercontinuum light source OTDR, characterized in that: the device comprises a mode-locked laser (1), a first polarization controller (2), a high-speed electro-optic modulator (3), a microwave signal source (4), a second polarization controller (5), a pulse light amplifier (6), a high-nonlinearity optical fiber (7), a first tunable optical filter (8), an optical isolator (9), a 1 x 2 optical fiber coupler (10), an optical circulator (11), an optical fiber to be tested (12), a variable optical delay line (13), a first photoelectric detector (14), an optical amplifier (15), a second tunable optical filter (16), a second photoelectric detector (17), an oscilloscope (18) and a computer (19);
the exit end of the mode-locked laser (1) is connected with the incident end of the first polarization controller (2); the emergent end of the first polarization controller (2) is connected with the incident end of the high-speed electro-optic modulator (3) through a single-mode optical fiber jumper; the emergent end of the high-speed electro-optic modulator (3) is connected with the incident end of the second polarization controller (5) through a single-mode optical fiber jumper; the signal output end of the microwave signal source (4) is connected with the radio frequency input end of the high-speed electro-optical modulator (3) through a high-frequency coaxial cable; the second polarization controller (5) is connected with the incident end of the pulse light amplifier (6) through a single-mode optical fiber jumper; the emergent end of the pulse light amplifier (6) is connected with the incident end of the high nonlinear optical fiber (7) through a single-mode optical fiber jumper; the emergent end of the high nonlinear optical fiber (7) is connected with the incident end of the first tunable optical filter (8) through a single-mode optical fiber jumper; the emergent end of the first tunable optical filter (8) is connected with the incident end of an optical isolator (9) through a single-mode optical fiber jumper; the emergent end of the optical isolator (9) is connected with the incident end of the 1 multiplied by 2 optical fiber coupler (10) through a single-mode optical fiber jumper;
the first emergent end of the 1 multiplied by 2 optical fiber coupler (10) is connected with the incident end of the optical circulator (11) through a single-mode optical fiber jumper; the reflection end of the optical circulator (11) is connected with the incidence end of the optical fiber (12) to be tested; the exit end of the optical circulator (11) is connected with the entrance end of the optical amplifier (15) through a single-mode optical fiber jumper; the exit end of the optical amplifier (15) is connected with the incident end of the second tunable optical filter (16); the exit end of the second tunable optical filter (16) is connected with the incident end of a second photoelectric detector (17) through a single-mode optical fiber jumper; the emergent end of the second photoelectric detector (17) is connected with the first signal input end of the oscilloscope (18) through a single-mode optical fiber jumper;
the second emergent end of the 1 multiplied by 2 optical fiber coupler (10) is connected with the incident end of the variable optical delay line (13) through a single-mode optical fiber jumper; the exit end of the variable optical delay line (13) is connected with the incident end of the first photoelectric detector (14) through a single-mode optical fiber jumper; the emergent end of the first photoelectric detector (14) is connected with the second signal incident end of the oscilloscope (18); the exit end of the oscilloscope (18) is connected with the signal entrance end of the computer (19).
2. A supercontinuum light source OTDR based method, implemented on the supercontinuum light source OTDR based device of claim 1, characterized in that, the method is implemented by the following steps:
firstly, a mode-locking optical pulse signal output by a mode-locking laser (1) is adjusted in polarization state through a first polarization controller (2), and then a microwave signal source (4) inputs the output sine wave signal as a modulation signal into a high-speed electro-optical modulator (3); mode-locking optical pulses and sine wave signals are respectively input into the high-speed electro-optical modulator (3) through an incident end and a radio frequency port of the high-speed electro-optical modulator (3), and high-quality modulation of the sine radio frequency signals on the pulse signals can be realized by controlling bias voltage of a microwave signal source (4); the signal continues to pass through a second polarization controller (5) to adjust the polarization state, the output pulse is subjected to power amplification through a pulse optical amplifier (6) and then is injected into a high nonlinear optical fiber (7) for transmission, and the output signal is influenced by various nonlinear effects such as self-phase modulation, cross-phase modulation, four-wave mixing, stimulated Raman scattering and the like and also influenced by the dispersion property of the optical fiber; modulation instability effects caused by interaction between nonlinearity and dispersion can cause optical pulse spectrum broadening to generate a supercontinuum; the first tunable optical filter (8) selects a proper filtering center and filtering bandwidth to filter the generated supercontinuum; the filtered signal enters a 1 multiplied by 2 optical fiber coupler (10) to be divided into two paths after being isolated by an optical isolator (9); one path enters the optical fiber (12) to be tested after being looped by the optical circulator (11) to generate back scattering; the output end of the optical circulator (11) is connected with an optical amplifier (15) to amplify the reflected signal, backward Rayleigh scattered light and Fresnel reflected light are filtered out by a second tunable optical filter (16), and the optical signal is converted into an electrical signal by a second photoelectric detector (17) and then input into an oscilloscope (18) to acquire a time sequence;
the other path of optical signal is used as a reference optical signal, and the optical path of the reference light is adjusted through a variable optical delay line (13) to calibrate a zero point; then inputting the first photoelectric detector (14) to be connected to an oscilloscope (18) for collecting time sequence; and finally, processing the data by using a computer (19), and determining an optical fiber connection point, an optical fiber terminal or a breakpoint by calculating a correlation function between the reference light and the backward Rayleigh scattering signal.
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