CN104426602A - Optical time-domain reflectometer - Google Patents
Optical time-domain reflectometer Download PDFInfo
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- CN104426602A CN104426602A CN201310380182.5A CN201310380182A CN104426602A CN 104426602 A CN104426602 A CN 104426602A CN 201310380182 A CN201310380182 A CN 201310380182A CN 104426602 A CN104426602 A CN 104426602A
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Abstract
The invention discloses an optical time-domain reflectometer comprising a trigger, a laser, an attenuator, a circulator, an up-conversion single-photon detector and a time-to-digital converter. The optical time-domain reflectometer (OTDR) of the invention employs the up-conversion single-photon detector. The up-conversion single-photon detector employs a pump light wavelength of 1900 nm to 2000 nm to carry out narrowband filtering on sum frequency light, a noise equivalent power (NEP) lower than the NEP of a classic detector is obtained under the same quantum efficiency, and the NEP value can reach -140dbm. The lower the NEP value is, the larger the detected dynamic range is. Therefore, the up-conversion single-photon detector effectively increases the detectable dynamic range of the OTDR, the detection resolution is improved, the measuring time is reduced, and dead zones after a Fresnel reflection peak are effectively prevented.
Description
Technical field
The present invention relates to fiber optic communication field, particularly relate to a kind of fiber optical time domain reflection instrument.
Background technology
At present, along with the development of optical communication, an important branch in optical communication---Fibre Optical Communication Technology (the Optical Fiber Communications) advantage such as high and signal attenuation is little with its transmission frequency bandwidth, anti-interference, the transmission means such as replacement cables, microwave communication gradually, becomes prevailing transmission mode in world communication.Optical fiber communication utilizes light wave to make carrier wave, using optical fiber as transmission medium, information reached the communication mode at another place from one, be referred to as " wired " optical communication.Therefore, the quality of optical fiber property directly affects speed and the distance of optical signal transmission.
The situations such as thunder and lightning, earthquake and construction easily cause the damage of optical fiber, cause the interruption of optical communication.In order to reduce the loss, diagnose, repair the optical fiber of damage to seem particularly important in time.Fiber optical time domain reflection instrument (Optical Time-Domain Reflectometer, OTDR) according to back scattering and the Fresnel inversion principle of light, the rear orientation light produced when utilizing light to propagate in a fiber is to obtain the information of attenuated optical signal, can be used for measuring optical fiber decay and splicing loss, positioning optical waveguides fault point, analyzing the loss distribution situation etc. of optical fiber along length, is requisite instrument in optical cable construction, maintenance and monitoring.
Traditional OTDR system mainly adopts classical photo-detector, such as: photomultiplier (the Photomultiplier Tube under linear model, PMT), PIN photodiode and avalanche photodide (Avalanche Photo Diode, APD) etc., the signal that photo-detector exports is proportional to the size of Rayleigh reflective light intensity.
Those skilled in the art adopt above-mentioned OTDR diagnose optical fiber time, find that there is following shortcoming:
The dynamic range that OTDR can measure is relevant with noise equivalent power (Noise Equivalent Power, NEP), and NEP value is lower, and the dynamic range that can measure is larger.Photo-detector due to classics has larger dark current and thermal noise, and the value of OTDR is generally-110dbm, and the dynamic range causing OTDR to measure is less.
Summary of the invention
In view of this, the invention provides a kind of fiber optical time domain reflection instrument, single-photon detector is changed in employing, NEP value can reach-140dbm, effectively increases the dynamic range that OTDR can measure.
A kind of fiber optical time domain reflection instrument, described device comprises:
Trigger, laser, attenuator, circulator, upper conversion single-photon detector and time-to-digit converter;
Described trigger is for exporting the electric impulse signal of predeterminated frequency;
The electric impulse signal trigger laser that described trigger exports produces the pulse light of same frequency, described pulse light incides described circulator after described attenuator attenuates, the pulse light exported from described circulator incides detection optical fiber, pulse light obtains rear orientation light and exports circulator to after detection optical fiber Rayleigh scattering, and described rear orientation light incides upper conversion single-photon detector after circulator exports;
Described upper conversion single-photon detector is used for pump light and described rear orientation light being carried out nonlinear optics and frequency, narrow-band filtering is carried out to frequency light, by after narrow-band filtering with frequency light convert to the TTL gate TTL signal of telecommunication export, described pump wavelength is 1900nm to 2000nm;
Described trigger exports electric impulse signal to time-to-digit converter, and described upper conversion single-photon detector exports the TTL signal of telecommunication to time-to-digit converter;
Described time-to-digit converter utilizes photon counting corresponding on electric impulse signal detection optical fiber position different from TTL electric signal measurement;
Wherein, light signal laser, attenuator, circulator and on change between single-photon detector and transmitted by polarization maintaining optical fibre.
Optionally, described upper conversion single-photon detector comprises:
Volume Bragg grating, described Volume Bragg grating is used for carrying out narrow-band filtering to frequency light.
Optionally,
The size of described Volume Bragg grating is more than or equal to the cube of 3.5mm*3.5mm*16mm.
Optionally, described trigger comprises:
Microwave signal generator and encoder;
Described microwave signal generator is for exporting inceptive impulse signal;
Described encoder is used for encoding to described inceptive impulse signal, exports the electric impulse signal of predeterminated frequency.
Optionally, the frequency of the inceptive impulse signal of described microwave signal generator output comprises:
10GHz。
Optionally,
Described laser output power is 1W, and wavelength is 150.12nm, and pulse duration is that 50ps to 10 μ s is tunable.
Optionally, described upper conversion single-photon detector comprises:
Avalanche silicon diode.
Optionally,
The time jitter jitter of described avalanche silicon diode is 500ps.
Optionally,
Light signal laser, attenuator, circulator and on change between single-photon detector and transmitted by monomode fiber;
Then described device also comprises:
Polarization Controller, for being adjusted to TM by pump light and described rear orientation light
00the polarised light of pattern.
As shown in the above, the present invention has following beneficial effect:
The invention provides a kind of fiber optical time domain reflection instrument, PMT is adopted with prior art, the OTDR of the classical photo-detector such as PIN and APD is different, OTDR in the present invention changes single-photon detector on adopting, upper conversion single-photon detector adopts the pump wavelength of 1900nm to 2000nm, narrow-band filtering is carried out to frequency light, the NEP lower than classical detector is obtained under identical quantum efficiency, its NEP value can reach-140dbm, because the value of NEP is lower, the dynamic range detected is larger, upper conversion single-photon detector effectively increases the dynamic range that OTDR can measure, improve the resolution of detection.
Accompanying drawing explanation
In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.
Fig. 1 is a kind of fiber optical time domain reflection instrument of the present invention embodiment one structural representation;
Fig. 2 is a kind of fiber optical time domain reflection instrument of the present invention embodiment two structural representation;
Fig. 3 is that a measurement result schematic diagram tested by a kind of fiber optical time domain reflection instrument of the present invention;
Fig. 4 is that two measurement result schematic diagrames tested by a kind of fiber optical time domain reflection instrument of the present invention;
Fig. 5 is that three measurement result schematic diagrames tested by a kind of fiber optical time domain reflection instrument of the present invention;
Fig. 6 (1) is the measurement result schematic diagram of a kind of fiber optical time domain reflection instrument experiment of the present invention 40 to 120km detection optical fibers;
Fig. 6 (2) is the measurement result schematic diagram of a kind of fiber optical time domain reflection instrument experiment of the present invention 4 100 to 216km detection optical fibers;
Fig. 6 (3) tests four Fig. 6 (2) back end reflective peak 602 for a kind of fiber optical time domain reflection instrument of the present invention and amplifies rear schematic diagram;
Fig. 6 (4) is the detection optical fiber measurement result schematic diagram of a kind of fiber optical time domain reflection instrument experiment of the present invention 4 100 to 221km;
Fig. 6 (5) tests four Fig. 6 (4) back end reflective peak 603 for a kind of fiber optical time domain reflection instrument of the present invention and amplifies rear schematic diagram;
Fig. 6 (6) tests four Fig. 6 (1) for a kind of fiber optical time domain reflection instrument of the present invention and combines schematic diagram with Fig. 6 (2) result of detection;
Fig. 6 (7) tests four Fig. 6 (6) back end reflective peak 602 for a kind of fiber optical time domain reflection instrument of the present invention and amplifies rear schematic diagram;
Fig. 6 (8) tests four Fig. 6 (1) for a kind of fiber optical time domain reflection instrument of the present invention and combines schematic diagram with Fig. 6 (4) result of detection;
Fig. 6 (9) tests four Fig. 6 (8) back end reflective peak 603 for a kind of fiber optical time domain reflection instrument of the present invention and amplifies rear schematic diagram.
Embodiment
The invention discloses a kind of fiber optical time domain reflection instrument, single-photon detector changed in employing, the dynamic range achieving OTDR systematic survey is large, resolution is high, the little advantage of Measuring Time section and blind area.
Below in conjunction with accompanying drawing and experimental result, the specific embodiment of the invention is described in detail.
Embodiment one
Fig. 1 is a kind of fiber optical time domain reflection instrument of the present invention embodiment one structural representation, and described device comprises:
Trigger 101, laser 102, attenuator 103, circulator 104, upper conversion single-photon detector 105 and time-to-digit converter 106.
Described trigger 101 is for exporting the electric impulse signal of predeterminated frequency.
Optionally, described trigger 101 comprises: microwave signal generator 107 and encoder 108,
Described microwave signal generator 107 is for exporting inceptive impulse signal;
Described encoder 108, for encoding to described inceptive impulse signal, exports the electric impulse signal of predeterminated frequency.
Here it should be noted that, trigger 101 can also be made up of other the equipment that can export predeterminated frequency electric impulse signal, repeats no longer one by one here.
Optionally, the model of microwave signal generator is Agilent N5183A, can send the inceptive impulse signal of 10GHz;
Encoder is the NP1800A that peace is stood, can the rear electric impulse signal exporting predeterminated frequency of initialize signal coding.
The electric impulse signal trigger laser 102 that described trigger 101 exports produces the pulse light of same frequency, described pulse light incides described circulator 104 after described attenuator 103 is decayed, and the pulse light exported from described circulator 104 incides detection optical fiber.
Described trigger 101 is connected with laser 102, and the electric impulse signal of the predeterminated frequency that trigger exports is the triggering signal of laser 102, and trigger laser 102 produces the pulse light of same frequency.
Optionally, described laser 102 range of wavelengths is 1900nm to 2000nm, and power output is 1W.Concrete, can adopt the QCL-100/200 narrow spaces laser of quantum communication company, pulse duration is tunable from 50ps to 10 μ s, and output pulse signal optical wavelength is 150.12nm.
The pulse light peak power exported due to laser is 1W, and the power needed when detecting is about 250mW.Therefore, pulse light input attenuator 103 is decayed, after reaching the luminous power needed for detection, export circulator 104 to.
Described circulator 104 is multiport devices, and the transmission of light can only be gone in ring along one direction, is isolation in the other direction.
Incide detection optical fiber from the pulse light of circulator 104 output to detect.
Pulse light obtains rear orientation light and exports circulator 104 to after detection optical fiber Rayleigh scattering, and described rear orientation light incides upper conversion single-photon detector 105 after circulator 104 exports.
Rear orientation light incides circulator 104, after circulator exports, incide upper conversion single-photon detector 105.
Wherein, the entrance port of pulse light and the incident circulator 104 of rear orientation light, and the exit portal exporting circulator is not identical.
In this example, pulse light laser 102, attenuator 103, between circulator 104 and detection optical fiber, and rear orientation light detection optical fiber, circulator 104 and on change between single-photon detector 105 and transmitted by polarization maintaining optical fibre.Polarization maintaining optical fibre guarantees that pulse light and rear orientation light are with TM
00mode transfer.
Described upper conversion single-photon detector 105 is for carrying out nonlinear optics and frequency by pump light and described rear orientation light, narrow-band filtering is carried out to frequency light, by after narrow-band filtering with frequency light convert to the TTL gate TTL signal of telecommunication export, described pump wavelength is 1900nm to 2000nm.
Optionally, pump light is exported by the single-mode laser of Advalue company.Described pump light λ
1, rear orientation light λ
2, and frequency light λ
3between pass be:
Wherein, and frequency light λ
3be definite value in the system identical in waveguide, temperature is fixing.
Described and frequently light λ
3it is the definite value of an experimental detection.Such as, in practical application of the present invention, 50 DEG C time, and frequency light λ
3for 864nm.When OTDR system parameters is fixed, and frequency light is definite value, meets formula (1) between pump light and rear orientation light.
Optionally, the present invention changes the wave-length coverage of the pump light that single-photon detector 105 adopts into 1900nm to 2000nm, compared with prior art, have employed the longer pump light of wavelength to realize nonlinear optics and frequency.Pump wavelength is longer, on the one hand, can avoid the noise that convert light under the Spontaneous Parametric of pump light is brought; On the other hand, when pumping wavelength is shorter, Raman noise is Stokes photon; When pumping wavelength is longer, Raman noise is anti-Stokes photon.Under the same terms, the cloth inning of anti-Stokes photon is fewer than Stokes photon, which reduces the noise of whole upper conversion single-photon detector 105, has lower NEP value than other detector.Because NEP value is lower, detectable dynamic range is larger.Therefore, when identical rear orientation light is incident, the dynamic range detected than other detector is large.Equally, when obtaining identical dynamic range, upper conversion single-photon detector 105 can reduce the optical signal pulses width of rear orientation light input, namely reduces the pulse duration of pulse light, improves the resolution sizes of detection.
Optionally, upper conversion single-photon detector 105 comprises Volume Bragg grating, described Volume Bragg grating for carrying out narrow-band filtering to frequency light.
The minimum dimension of Volume Bragg grating is the cube of long 16mm, 3.5mm, high 3.5mm, and frequency light incides the plane of incidence of 3.5mm*3.5mm.In embodiment, Volume Bragg grating can be adopted to be of a size of long 16mm, 8mm, high 6mm.Volume Bragg grating selects direction and the wavelength of Bragg diffraction according to Bragg condition (2dsin θ=n λ).Volume Bragg grating has very narrow wavelength bandwidth, and wavelength bandwidth is between 0.02nm to 0.1nm, in embodiment, wavelength bandwidth can be adopted to be 0.05nm.The reflected wavelength range of Volume Bragg grating is between 830nm to 880nm.Carry out after narrow-band filtering with frequency light through Volume Bragg grating, filtering major part noise, makes NEP value can reach-140dbm/Hz ∧ (1/2).That is, in the present invention, upper conversion single-photon detector can detect the light of-140dbm, at identical conditions, on other compared with sub-detector of converting unit, when measuring identical distance, just has higher resolution with employing.
Further, under upper conversion single-photon detector 105 is operated in free-run pattern, compared with traditional detector, detection time is reduced.
Compared with indium GaAs (InGaAs) the avalanche diode single-photon detector worked under gate-control signal, detection time is little three orders of magnitude, the time of detection is 10 minutes.
Further, compared with the OTDR of superconducting single-photon detector, without the need to liquid nitrogen refrigerating, cost is low, and volume is little.
Optionally, described upper conversion single-photon detector 105 comprises: avalanche silicon diode.
Optionally, the time jitter jitter of described avalanche silicon diode is 500ps.
Determine in OTDR that the accuracy of the distance that a time occurs is the positioning precision of OTDR, the positioning precision of the OTDR of upper conversion single-photon detector depends on the time jitter of conversion single-photon detector, and time jitter is less, and positioning precision is higher.Pass between time jitter t and positioning precision L is:
Wherein, c is the light velocity, and n is the refractive index of optical fiber.
In experiment, as n=1.5, time jitter is 500ps, then positioning precision is 10cm.
Avalanche silicon diode in upper conversion single-photon detector 105, does not have afterpulse phenomenon, the blind area occurred after effectively avoiding Fresnel reflecting peak.
Described upper conversion single-photon detector is used for pump light and described rear orientation light being carried out nonlinear optics and frequency, will convert the TTL gate TTL signal of telecommunication to export with frequency light;
Described trigger 101 exports electric impulse signal to time-to-digit converter 106, and described upper conversion single-photon detector 105 exports the TTL signal of telecommunication to time-to-digit converter 106.
Trigger 101 exports the electric impulse signal of time-to-digit converter 106 to as beginning Start signal; Upper conversion single-photon detector 105 exports the TTL signal of telecommunication of time-to-digit converter 106 to as end Stop signal.
Described time-to-digit converter 106 utilizes photon counting corresponding on electric impulse signal detection optical fiber position different from TTL electric signal measurement.
As shown in the above, the present invention has following beneficial effect:
The invention provides a kind of fiber optical time domain reflection instrument, PMT is adopted with prior art, the OTDR of the classical photo-detector such as PIN and APD is different, OTDR in the present invention changes single-photon detector on adopting, upper conversion single-photon detector adopts the pump wavelength of 1900nm to 2000nm, narrow-band filtering is carried out to frequency light, the NEP lower than classical detector is obtained under identical quantum efficiency, its NEP value can reach-140dbm, because the value of NEP is lower, the dynamic range detected is larger, upper conversion single-photon detector effectively increases the dynamic range that OTDR can measure, improve the resolution of detection,
Upper conversion single-photon detector adopts the mode of operation of free-run, effectively reduces Measuring Time;
Compared with indium GaAs (InGaAs) the avalanche diode single-photon detector worked under gate-control signal, detection time is little three orders of magnitude;
Compared with the OTDR of superconducting single-photon detector, without the need to liquid nitrogen refrigerating, cost is low, and volume is little;
In upper conversion single-photon detector, avalanche silicon diode does not have afterpulse linear, the blind area occurred after effectively avoiding Fresnel reflecting peak.
Embodiment two
Fig. 2 is a kind of fiber optical time domain reflection instrument of the present invention embodiment two structural representation, and compared with embodiment one, described device also comprises Polarization Controller, and described device comprises:
Trigger 101, laser 102, attenuator 103, circulator 104, upper conversion single-photon detector 105, time-to-digit converter 106 and Polarization Controller 201.
Wherein, light signal laser 102, attenuator 103, circulator 104 and on change between single-photon detector 106 and transmitted by monomode fiber.
Pulse light laser 102, attenuator 103, between circulator 104 and detection optical fiber, and rear orientation light detection optical fiber, circulator 104, Polarization Controller 201, on change between single-photon detector 105 and transmitted by monomode fiber.
The electric impulse signal trigger laser 102 that described trigger 101 exports produces the pulse light of same frequency, described pulse light incides described circulator 104 after described attenuator 103 is decayed, the pulse light exported from described circulator 104 incides detection optical fiber, pulse light obtains rear orientation light and exports circulator 104 to after detection optical fiber Rayleigh scattering, described rear orientation light incides Polarization Controller 201 after circulator 104 exports, and rear orientation light is adjusted to TM by described Polarization Controller 201
00the polarised light of pattern exports conversion single-photon detector 105 to;
Described upper conversion single-photon detector 105 is for carrying out nonlinear optics and frequency by pump light and described rear orientation light, Volume Bragg grating in upper conversion single-photon detector 105 carries out narrow-band filtering to frequency light, by after narrow-band filtering with frequency light convert to the TTL gate TTL signal of telecommunication export;
Described trigger 101 exports electric impulse signal to time-to-digit converter 106, and described upper conversion single-photon detector 105 exports the TTL signal of telecommunication to time-to-digit converter 106;
Described time-to-digit converter 106 utilizes photon counting corresponding on electric impulse signal detection optical fiber position different from TTL electric signal measurement.
In fiber optical time domain reflection instrument, description and embodiment one type such as parameter of equipment, repeat here no longer one by one.
Below in conjunction with concrete fiber-optic probe experimental result, the beneficial effect of fiber optical time domain reflection instrument provided by the present invention is described further.What adopt in experiment is the fiber optical time domain reflection instrument described in embodiment two, and light signal is transmitted by monomode fiber between all parts.
Experiment one, experiment two and experiment four are analyses of the monomode fiber spatial resolution experimental result to fiber optical time domain reflection instrument detection different length; Experiment three is the interpretations of result to the dynamic range that fiber optical time domain reflection instrument detection 170km optical fiber detects.
Experiment one
Experimental setup parameters: the monomode fiber of detection 12.5km, the frequency of electric impulse signal is 8kHz, pulse duration is 500ps, the pip of an extruding point as pulse light is set at distance measurement optical fiber connector 15cm place, detection time 3 minutes (detection time can also be 10 minutes), obtains the measurement result of Fig. 3.
Wherein, the relation in the frequency f of electric impulse signal and optical fiber between light velocity v, detection optical fiber length L meets formula (3):
Interpretation: from the measurement result in Fig. 3, there are two reflection peaks 301 and 302 in data result front end, this is because the isolation of circulator 104 has certain error to cause.Distance between reflection peak 301 and reflection peak 302 is 1m, coincide with the distance of photo-signal channel in the circulator 104 of actual measurement.
There are two reflection peaks 303 and 304 in the rear end of Fig. 3 measurement data result, these two reflection peaks are by the primary event of the pip pulse signals light of distance measurement optical fiber connector 15cm, and the other primary event formation of detection optical fiber end pulse signals light.As the above analysis, the monomode fiber of fiber optical time domain reflection instrument detection 12.5km provided by the present invention, spatial resolution at least can reach 15cm.
Experiment two
Experimental setup parameters: the monomode fiber of detection 86km, the frequency obtaining electric impulse signal according to formula (2) is 1kHz, and pulse duration is 10ns, accesses the FC-FC single-mode fiber jumper that a length is 2m in detection optical fiber end, detection time 3 minutes, obtains the measurement result of Fig. 4.
Interpretation: as shown in Figure 4, there are two reflection peaks 401 and 402 in experimental data rear end, these two reflection peaks are by the primary event of detection optical fiber end pulse signals light, and the FC-FC single-mode fiber jumper of 2m is formed for the primary event of pulse light.Distance in Fig. 4 between reflection peak 401 and reflection peak 402 is 2m, coincide with actual measured results.As the above analysis, the monomode fiber of fiber optical time domain reflection instrument detection 86km provided by the present invention, spatial resolution at least can reach 2m.
Experiment three
Experimental setup parameters: the monomode fiber of detection 170km, the frequency obtaining electric impulse signal according to formula (2) is 500Hz, pulse duration is 10 μ s, pulse light input attenuator 103 is decayed, when making the rear orientation light that reflects from detection optical fiber by upper conversion single-photon detector 105 count pick up, close to saturation count, detection time 3 minutes, obtains the measurement result of Fig. 5.
As seen from Figure 5, make to change single-photon detector at 0-20km place and be in off position, be used for avoiding damaging due to reasons such as misoperations changing single-photon detector.Data result shows, and the dynamic range that upper conversion single-photon detector can detect can reach 45dbm, (in figure 22.5dbm*2=45dbm), about 125km.
Experiment four
Experimental setup parameters: the monomode fiber of detection 216km, the frequency of electric impulse signal is 400Hz, and pulse duration is that the detection optical fiber of 10 μ s, 216km is made up of the optical fiber of two sections of 108km, and detection time 3 minutes, obtains the measurement result of Fig. 6.In Fig. 6 (1)-Fig. 6 (5), abscissa represents the number of bin.
Because the detection optical fiber of 216km is long, be divided into two sections of optical fiber and detect.When upper conversion single-photon detector does not add gate-control signal, detection be the detection optical fiber of 0 to 120km, regulated attenuator make conversion single-photon detector be counted as 44W time, measure 3 minutes, obtain the measurement result of Fig. 6 (1).
Above change (duty ratio is 60%) when single-photon detector adds gate-control signal, detection be the detection optical fiber of 100 to 216km, adjustment doors signal lag, conversion single-photon detector is counted minimum, when regulated attenuator is decreased to undamped gradually, upper conversion single-photon detector is counted as 67W, measures 3 minutes, obtain the data result of Fig. 6 (2), after Fig. 6 (2) back end reflective peak 602 amplifies as shown in Fig. 6 (3).
The FC-FC single-mode fiber jumper of 5m is added at the detection optical fiber end of 216km.Above change (duty ratio is 60%) when single-photon detector adds gate-control signal, detection be the detection optical fiber of 100 to 221km, adjustment doors signal lag, conversion single-photon detector is counted minimum, when regulated attenuator is decreased to undamped gradually, upper conversion single-photon detector is counted as 60W, measures 3 minutes, obtain the data result of Fig. 6 (4), after Fig. 6 (4) back end reflective peak 603 amplifies as shown in Fig. 6 (5).
The detection data result of the detection data result of Fig. 6 (1) 0 to 120km optical fiber and Fig. 6 (2) 100 to 216km optical fiber is combined, with front end reflection peak 601 for node, obtain the result of detection (clear in order to show, Fig. 6 (6) is the result schematic diagram after amplification 5 times) of whole 216 detection optical fibers shown in Fig. 6 (6).Fig. 6 (7) is the enlarged drawing at Fig. 6 (6) back end reflective peak 602, and as can be seen from the figure, position, back end reflective peak 602 is 214302m.
The detection data result of the detection data result and Fig. 6 (4) 100 to 221km optical fiber of scheming (1) 0 to 120km optical fiber is combined, with front end reflection peak 601 for node, obtain the result of detection (clear in order to show, Fig. 6 (8) is the result schematic diagram after amplification 5 times) of whole 221 detection optical fibers shown in Fig. 6 (8).Fig. 6 (9) is the enlarged drawing at Fig. 6 (8) back end reflective peak 603, and as can be seen from the figure, position, back end reflective peak 603 is 214307m.
According to result of detection, when detecting 216km optical fiber, the resolution of 1m can be reached.
When Fig. 6 (3) and Fig. 6 (5) back end reflective peak difference 444-439=5 bin(does not have a specified otherwise, 1 bin is 512ps*20=10.24ns), it apart from S-phase difference is
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (9)
1. a fiber optical time domain reflection instrument, is characterized in that, described device comprises:
Trigger, laser, attenuator, circulator, upper conversion single-photon detector and time-to-digit converter;
Described trigger is for exporting the electric impulse signal of predeterminated frequency;
The electric impulse signal trigger laser that described trigger exports produces the pulse light of same frequency, described pulse light incides described circulator after described attenuator attenuates, the pulse light exported from described circulator incides detection optical fiber, pulse light obtains rear orientation light and exports circulator to after detection optical fiber Rayleigh scattering, and described rear orientation light incides upper conversion single-photon detector after circulator exports;
Described upper conversion single-photon detector is used for pump light and described rear orientation light being carried out nonlinear optics and frequency, narrow-band filtering is carried out to frequency light, by after narrow-band filtering with frequency light convert to the TTL gate TTL signal of telecommunication export, described pump wavelength is 1900nm to 2000nm;
Described trigger exports electric impulse signal to time-to-digit converter, and described upper conversion single-photon detector exports the TTL signal of telecommunication to time-to-digit converter;
Described time-to-digit converter utilizes photon counting corresponding on electric impulse signal detection optical fiber position different from TTL electric signal measurement;
Wherein, light signal laser, attenuator, circulator and on change between single-photon detector and transmitted by polarization maintaining optical fibre.
2. device according to claim 1, is characterized in that, described upper conversion single-photon detector comprises:
Volume Bragg grating, described Volume Bragg grating is used for carrying out narrow-band filtering to frequency light.
3. device according to claim 2, is characterized in that,
The size of described Volume Bragg grating is more than or equal to the cube of 3.5mm*3.5mm*16mm.
4. device according to claim 1, is characterized in that, described trigger comprises:
Microwave signal generator and encoder;
Described microwave signal generator is for exporting inceptive impulse signal;
Described encoder is used for encoding to described inceptive impulse signal, exports the electric impulse signal of predeterminated frequency.
5. method according to claim 4, is characterized in that, the frequency of the inceptive impulse signal that described microwave signal generator exports comprises:
10GHz。
6. device according to claim 1, is characterized in that,
Described laser output power is 1W, and wavelength is 150.12nm, and pulse duration is that 50ps to 10 μ s is tunable.
7. device according to claim 1, is characterized in that, described upper conversion single-photon detector comprises:
Avalanche silicon diode.
8. device according to claim 7, is characterized in that,
The time jitter jitter of described avalanche silicon diode is 500ps.
9. the device according to claim 1-8 any one, is characterized in that,
Light signal laser, attenuator, circulator and on change between single-photon detector and transmitted by monomode fiber;
Then described device also comprises:
Polarization Controller, for being adjusted to TM by pump light and described rear orientation light
00the polarised light of pattern.
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| CN113037367A (en) * | 2021-03-24 | 2021-06-25 | 广东电网有限责任公司清远供电局 | Optical time domain reflectometer |
| CN113517922A (en) * | 2020-04-09 | 2021-10-19 | 华为技术有限公司 | Signal detection method and optical time domain reflectometer |
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|---|---|---|---|---|
| CN102243107A (en) * | 2011-04-20 | 2011-11-16 | 张强 | High-sensitivity up-conversion single photon detection system |
| CN102506904B (en) * | 2011-10-17 | 2014-05-21 | 南京大学 | Spontaneous Brillouin scattering optical time domain reflectometer based on superconductive nanowire single-proton detector |
| CN103051377A (en) * | 2012-12-26 | 2013-04-17 | 桂林聚联科技有限公司 | Method for precisely positioning fault of optical cable by utilizing rayleigh scattering and coherent optical time domain reflection technology |
| CN203504566U (en) * | 2013-08-27 | 2014-03-26 | 张强 | Optical time-domain reflectometer |
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2013
- 2013-08-27 CN CN201310380182.5A patent/CN104426602B/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113517922A (en) * | 2020-04-09 | 2021-10-19 | 华为技术有限公司 | Signal detection method and optical time domain reflectometer |
| CN113037367A (en) * | 2021-03-24 | 2021-06-25 | 广东电网有限责任公司清远供电局 | Optical time domain reflectometer |
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