CN211740563U - Optical time domain reflectometer - Google Patents
Optical time domain reflectometer Download PDFInfo
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- CN211740563U CN211740563U CN202020631686.5U CN202020631686U CN211740563U CN 211740563 U CN211740563 U CN 211740563U CN 202020631686 U CN202020631686 U CN 202020631686U CN 211740563 U CN211740563 U CN 211740563U
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Abstract
The application discloses optical time domain reflectometer for detect a optic fibre that awaits measuring, it includes first light source module, first circulator, first detection module, first signal acquisition module, second light source module, second circulator, second detection module, second signal acquisition module and wavelength division multiplexer. The first light source module, the first circulator, the first detection module and the first signal acquisition module can realize the detection of the intensity change of the optical signal by matching with the wavelength division multiplexer, and can also be used for detecting the loss curve along the optical fiber link to be detected. The second light source module, the second circulator, the second detection module and the second signal acquisition module can realize the detection of the phase change of the optical signal by matching with the wavelength division multiplexer, and can also be used for detecting whether the optical fiber to be detected has the effects of stress, vibration and the like.
Description
Technical Field
The application relates to the technical field of optical fiber testing, in particular to an optical time domain reflectometer.
Background
When light is transmitted in an optical fiber, parameters such as the polarization state, power, wavelength, phase and the like of an optical signal can change due to the influence of environmental factors such as external disturbance, temperature, strain, displacement and the like on the optical fiber, and the optical fiber testing technology is a brand-new technology for obtaining the change information of the surrounding environment by detecting the parameters of the light in the optical fiber.
An Optical Time Domain Reflectometer (OTDR) is a main instrument in the field of optical fiber testing technology, and is widely used in maintenance and construction of optical cable lines, and can measure the length of an optical fiber, transmission attenuation of the optical fiber, joint attenuation, fault location, and the like. However, the general OTDR can only test the intensity change of the optical signal, and can only play a role when the optical cable is damaged, and when the optical fiber line is disturbed slightly and the loss is not very large, the monitoring effect of the general OTDR is not ideal, and the purpose of early warning cannot be achieved.
Because the light transmitted in the optical fiber is not only the intensity change, but also the phase and polarization state of the light are changed, and the change of the phase and polarization state is more sensitive than the intensity change, the phase-sensitive optical time domain reflectometer (phi-OTDR) manufactured by utilizing the characteristic that the phase of the light pulse transmitted in the optical fiber is changed along with the change of the line state is rapidly developed and applied, the phi-OTDR can detect whether the optical fiber line is disturbed slightly, the sensitivity of the OTDR is greatly improved, early warning can be realized, and the optical cable is prevented from being damaged. However, since the phi-OTDR uses a light source with strong coherence (line width <10KHz), it is not able to measure the loss curve as stably as the ordinary OTDR.
SUMMERY OF THE UTILITY MODEL
It is an object of the present application to provide an optical time domain reflectometer that can measure both loss profile and perturbation signal.
In order to achieve the above object, the present application provides an optical time domain reflectometer for detecting a to-be-detected optical fiber, including a first light source module, a first circulator, a first detection module, a first signal collection module, a second light source module, a second circulator, a second detection module, a second signal collection module, and a wavelength division multiplexer, wherein,
the first light source module is suitable for outputting first laser;
the first circulator receives light output by the first light source module through a first port thereof and outputs the light to the wavelength division multiplexer through a second port thereof, and light input from the second port of the first circulator is output from a third port of the first circulator;
the first detection module is connected with the third port of the first circulator and used for converting an optical signal output by the third port of the first circulator into an electric signal;
the first signal acquisition module is connected with the first detection module and is used for acquiring an electric signal of the first detection module;
the second light source module is suitable for outputting pulse laser, and the wavelength of the laser output by the first light source module is different from that of the laser output by the second light source module;
the second circulator receives the light output by the second light source module from the first end and outputs the light to the wavelength division multiplexer from the second port, and the light input from the second port of the second circulator is output from the third port of the second circulator;
the second detection module is directly or indirectly connected with the third port of the second circulator and is used for converting an optical signal output by the third port of the second circulator into an electric signal;
the second signal acquisition module is connected with the second detection module and is used for acquiring an electric signal of the second detection module;
the wavelength division multiplexer is suitable for being connected with an optical fiber to be tested, so that light with different wavelengths output by the first light source module and the second light source module is respectively input into the wavelength division multiplexer, the wavelength division multiplexer inputs two optical signals into the optical fiber to be tested, and backward scattered light of the light with different wavelengths in the optical fiber to be tested passes through the wavelength division multiplexer and then is respectively input into the second port of the first circulator and the second port of the second circulator.
Further, the second light source module includes second laser instrument, acousto-optic modulator and mixes bait fiber amplifier, the continuous laser process that the second laser instrument sent turn into the pulsed light behind the acousto-optic modulator, the pulsed light signal process mix and input after bait fiber amplifier enlargies the first port of second circulator.
Further, the optical time domain reflectometer further includes a first coupler and a second coupler disposed between the second laser and the acousto-optic modulator, the second coupler is adapted to split the laser input by the second laser 2 and output the split laser to the acousto-optic modulator and the first coupler, respectively, and the first coupler is configured to combine the backscattered light input by the third port of the second circulator and the light input by the second coupler, and then output the combined light to the second detection module.
Further, the second detection module is a photodiode.
Further, the first coupler is a 2 × 2 fiber coupler, and the second coupler is a 1 × 2 fiber coupler.
Further, the second laser is adapted to emit laser light with a linewidth of less than 10 kHz.
Further, the first light source module includes a first laser, and the first laser is an FP laser.
Further, the first detection module is an avalanche photodiode.
Compared with the prior art, the beneficial effect of this application lies in: the utility model discloses only use an optic fibre just can accomplish light path loss simultaneously and measure and vibration detection.
Drawings
FIG. 1 is a schematic view of one embodiment of the present application;
FIG. 2 is a schematic view of another embodiment of the present application;
in the figure: 11. a first light source module; 111. a first laser; 12. a first circulator; 13. a first detection module; 14. a first signal acquisition module; 21. a second light source module; 211. a second laser; 212. an acousto-optic modulator; 213. an erbium-doped fiber amplifier; 214. a second coupler; 22. a second circulator; 23. a second detection module; 24. a second signal acquisition module; 25. a first coupler; 3. a wavelength division multiplexer; 4. and (5) an optical fiber to be tested.
Detailed Description
The present application is further described below with reference to specific embodiments, and it should be noted that, without conflict, any combination between the embodiments or technical features described below may form a new embodiment.
In the description of the present application, it should be noted that, for the terms of orientation, such as "central", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., it indicates that the orientation and positional relationship shown in the drawings are based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, but does not indicate or imply that the device or element referred to must have a specific orientation, be constructed in a specific orientation, and be construed as limiting the specific scope of protection of the present application.
It is noted that the terms first, second and the like in the description and in the claims of the present application are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.
The terms "comprises," "comprising," and "having," and any variations thereof, in the description and claims of this application, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
As shown in fig. 1 and 2, the utility model provides an optical time domain reflectometer for detect a optic fibre 4 that awaits measuring, it includes first light source module 11, first circulator 12, first detection module 13, first signal acquisition module 14, second light source module 21, second circulator 22, second detection module 23, second signal acquisition module 24 and wavelength division multiplexer 3.
The first light source module 11 is adapted to output first laser light. In some embodiments, the first light source module 11 includes a first laser 111, and the first laser 111 is an FP laser having a spectral width of 5nm to 50 nm.
The first circulator 12 receives light output from the first light source module 11 by a first port thereof and outputs the light to the wavelength division multiplexer 3 by a second port thereof, and light input from the second port of the first circulator 12 is output from a third port thereof.
The first detection module 13 is connected to the third port of the first circulator 12, and is configured to convert an optical signal output from the third port into an electrical signal. In some embodiments, the first detection module 13 is an avalanche photodiode, which can convert an optical signal into an electrical signal and has an amplification function.
The first signal acquisition module 14 is connected to the first detection module 13, and is configured to acquire an electrical signal of the first detection module and implement analog-to-digital conversion of the signal.
The second light source module 21 is adapted to output a pulse laser having strong coherence, so that it can be used to detect a phase change of an optical signal. In some embodiments, the second light source module 21 includes a second laser 211 with a narrow line width, an acousto-optic modulator 212, and an erbium-doped fiber amplifier 213, where the second laser 211 is adapted to emit laser with a line width smaller than 10kHz, continuous laser light emitted by the second laser 211 is converted into pulsed light through the acousto-optic modulator 212, and the acousto-optic modulator 212 can modulate a pulse frequency and a pulse width, and a pulsed light signal output by the acousto-optic modulator 212 is amplified through the erbium-doped fiber amplifier 213 and input to the first port of the second circulator 22.
The second circulator 22 receives light output from the second light source module 21 by its first port and outputs the light to the wavelength division multiplexer 3 by its second port, and light input from the second port of the second circulator 22 is output from its third port.
In some embodiments, as shown in fig. 1, the second detection module 23 is connected to a third port of the second circulator 22, and the second detection module 23 is configured to convert an optical signal output from the third port into an electrical signal. In some embodiments, the second detection module 23 is selected from an Avalanche Photodiode (APD) or a Photodiode (PD) that converts optical signals to electrical signals.
The second signal collecting module 24 is connected to the second detecting module 23, and is configured to collect an electrical signal of the second detecting module 23 and implement signal analog-to-digital conversion.
In other embodiments, as shown in fig. 2, a first coupler 25 is disposed between the second detection module 23 and the third port of the second circulator 22, a second coupler 214 is disposed between the second laser 211 and the acousto-optic modulator 212 of the second light source module 21, the second coupler 214 is adapted to split the laser light input by the second laser 211 and output the split laser light to the acousto-optic modulator 212 and the first coupler 25, respectively, and the first coupler 25 is adapted to combine the backscattered light input from the third port of the second circulator 22 with the light input by the second coupler 214 as the reference light and output the combined light to the second detection module 23. Further, the first coupler 25 is a 2 × 2 fiber coupler, and the second coupler 214 is a 1 × 2 fiber coupler. The arrangement of the coupler 25 between the second circulator 22 and the second detection module 23 is advantageous for improving the signal-to-noise ratio of the system.
It should be noted that the wavelength of the laser light output by the first light source module 11 is not equal to the wavelength of the laser light output by the second light source module 21. The light with different wavelengths output by the first light source module 11 and the second light source module 21 is respectively input to the wavelength division multiplexer 3 through the first circulator 12 and the second circulator 22, the wavelength division multiplexer 3 inputs two kinds of optical signals to the optical fiber 4 to be detected, and the backscattered light of the light with different wavelengths in the optical fiber 4 to be detected passes through the wavelength division multiplexer 3 and then is respectively input to the second port of the first circulator 12 and the second port of the second circulator 22, and then is respectively input to the first detection module 13 and the second detection module 23.
The first light source module 11, the first circulator 12, the first detection module 13, and the first signal collection module 14, in cooperation with the wavelength division multiplexer 3, can realize detection of optical signal intensity variation, and also can be used to detect a loss curve along the link of the optical fiber 4 to be detected. The second light source module 21, the second circulator 22, the optional coupler 25, the second detection module 23, and the second signal collection module 24, in cooperation with the wavelength division multiplexer 3, can realize detection of phase change of an optical signal, that is, can be used to detect whether the optical fiber 4 to be detected has effects of stress, vibration, and the like. The utility model discloses only use an optic fibre just can accomplish light path loss and measure and vibration detection, under the limited condition of optic fibre core, the utility model provides an optical time domain reflectometer's advantage is more obvious.
The foregoing has described the general principles, essential features, and advantages of the application. It will be understood by those skilled in the art that the present application is not limited to the embodiments described above, which are merely illustrative of the principles of the application, but that various changes and modifications may be made without departing from the spirit and scope of the application, and these changes and modifications are intended to be within the scope of the application as claimed. The scope of protection claimed by this application is defined by the following claims and their equivalents.
Claims (8)
1. An optical time domain reflectometer for detecting a fiber to be detected is characterized by comprising a first light source module, a first circulator, a first detection module, a first signal acquisition module, a second light source module, a second circulator, a second detection module, a second signal acquisition module and a wavelength division multiplexer, wherein,
the first light source module is suitable for outputting first laser;
the first circulator receives light output by the first light source module through a first port thereof and outputs the light to the wavelength division multiplexer through a second port thereof, and light input from the second port of the first circulator is output from a third port of the first circulator;
the first detection module is connected with the third port of the first circulator and used for converting an optical signal output by the third port of the first circulator into an electric signal;
the first signal acquisition module is connected with the first detection module and is used for acquiring an electric signal of the first detection module;
the second light source module is suitable for outputting pulse laser, and the wavelength of the laser output by the first light source module is different from that of the laser output by the second light source module;
the second circulator receives the light output by the second light source module from the first end and outputs the light to the wavelength division multiplexer from the second port, and the light input from the second port of the second circulator is output from the third port of the second circulator;
the second detection module is directly or indirectly connected with the third port of the second circulator and is used for converting an optical signal output by the third port of the second circulator into an electric signal;
the second signal acquisition module is connected with the second detection module and is used for acquiring an electric signal of the second detection module;
the wavelength division multiplexer is suitable for being connected with an optical fiber to be tested, so that light with different wavelengths output by the first light source module and the second light source module is respectively input into the wavelength division multiplexer, the wavelength division multiplexer inputs two optical signals into the optical fiber to be tested, and backward scattered light of the light with different wavelengths in the optical fiber to be tested passes through the wavelength division multiplexer and then is respectively input into the second port of the first circulator and the second port of the second circulator.
2. The optical time domain reflectometer as in claim 1, wherein the second light source module comprises a second laser, an acousto-optic modulator and an erbium-doped fiber amplifier, the continuous laser emitted from the second laser is converted into a pulse light after passing through the acousto-optic modulator, and the pulse light is input to the first port of the second circulator after being amplified by the erbium-doped fiber amplifier.
3. The optical time domain reflectometer as in claim 2, further comprising a first coupler and a second coupler disposed between the second laser and the acousto-optic modulator, wherein the second coupler is adapted to output the laser light inputted from the second laser after being divided into two paths to the acousto-optic modulator and the first coupler, respectively, and the first coupler is configured to combine the backscattered light inputted from the third port of the second circulator with the light inputted from the second coupler and then output the combined light to the second detection module.
4. The optical time domain reflectometer as in claim 3 wherein the second detection module is a photodiode.
5. The optical time domain reflectometer as in claim 3 wherein the first coupler is a 2 x 2 fiber coupler and the second coupler is a 1 x 2 fiber coupler.
6. The optical time domain reflectometer as in claim 2 wherein the second laser is adapted to emit laser light having a linewidth of less than 10 kHz.
7. The optical time domain reflectometer as in claim 1 wherein the first light source module comprises a first laser, the first laser being a FP laser.
8. The optical time domain reflectometer as in claim 1 wherein the first detection module is an avalanche photodiode.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112578220A (en) * | 2020-11-26 | 2021-03-30 | 贵州电网有限责任公司 | Underground cable fault on-line positioning system and method |
| CN113375903A (en) * | 2021-05-14 | 2021-09-10 | 太原理工大学 | Optical fiber breakpoint positioning device |
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2020
- 2020-04-24 CN CN202020631686.5U patent/CN211740563U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112578220A (en) * | 2020-11-26 | 2021-03-30 | 贵州电网有限责任公司 | Underground cable fault on-line positioning system and method |
| CN113375903A (en) * | 2021-05-14 | 2021-09-10 | 太原理工大学 | Optical fiber breakpoint positioning device |
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