CN110487309B - Optical fiber detection method and system - Google Patents
Optical fiber detection method and system Download PDFInfo
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- CN110487309B CN110487309B CN201910870400.0A CN201910870400A CN110487309B CN 110487309 B CN110487309 B CN 110487309B CN 201910870400 A CN201910870400 A CN 201910870400A CN 110487309 B CN110487309 B CN 110487309B
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- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
- G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
- G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
- G01D5/35338—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using other arrangements than interferometer arrangements
- G01D5/35354—Sensor working in reflection
- G01D5/35358—Sensor working in reflection using backscattering to detect the measured quantity
- G01D5/35364—Sensor working in reflection using backscattering to detect the measured quantity using inelastic backscattering to detect the measured quantity, e.g. using Brillouin or Raman backscattering
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
- G01K11/322—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres using Brillouin scattering
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
- G01L1/242—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre
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Abstract
The embodiment of the invention provides an optical fiber detection method and an optical fiber detection system, wherein the optical fiber detection method comprises the following steps: the device comprises a laser, a sensing optical fiber, a first circulator, a second circulator and a collector; the laser sends a sensing pulse and a pumping pulse to the first circulator, and the sending time of the sensing pulse is earlier than that of the pumping pulse; the first circulator transmits sensing pulses and pumping pulses through a sensing optical fiber; the second circulator sends sensing pulses to the first circulator through the sensing optical fiber after receiving the sensing pulses, and the sensing pulses and the pumping pulses have stimulated Brillouin scattering effect in the sensing optical fiber to obtain sensing pulses carrying Brillouin scattering information; after receiving the sensing pulse carrying the Brillouin scattering information, the first circulator sends the sensing pulse carrying the Brillouin scattering information to the collector; and after receiving the sensing pulse carrying the Brillouin scattering information, the collector stores the Brillouin scattering information. By applying the technical scheme provided by the embodiment of the invention, optical fibers can be saved, and single-fiber long-distance detection is realized.
Description
Technical Field
The invention relates to the technical field of optical fiber sensing, in particular to an optical fiber detection method and an optical fiber detection system.
Background
The distributed optical fiber sensor takes optical fibers as transmission media, has the advantages of small volume, light weight, easy bending, small loss, good electromagnetic interference resistance and radiation resistance and the like, and has wide application requirements in important fields of monitoring the safety of intelligent power grids and oil field pipelines, monitoring key building structures of bridges, spacecraft wings and the like in the future. The Brillouin scattering information obtained by the distributed sensor based on Brillouin scattering comprises information such as Brillouin gain and Brillouin frequency shift, and is in linear relation with temperature and stress changes, so that the temperature and stress information can be measured.
At present, compared with Brillouin Optical Time Domain Reflectometry (BOTDR) technology based on a principle of Spontaneous Brillouin Scattering (SpBS), the Brillouin Optical Time Domain Analysis (BOTDA) technology based on a principle of Stimulated Brillouin Scattering (SBS) has greatly enhanced Scattering efficiency, but since laser frequencies at two ends of an Optical fiber in a conventional BOTDA system are not synchronous, a phase noise problem is caused, and in order to solve the problem, the conventional BOTDA system is improved, and a loop structure is additionally arranged in the BOTDA system, namely a guide Optical fiber with the same length as the sensing Optical fiber is additionally arranged besides the sensing Optical fiber. Although the problem of asynchronous frequency of lasers at two ends is effectively solved based on a loop technology in a long-distance BOTDA sensor, the improved BOTDA system has the advantages that a guide optical fiber is used for guiding sensing pulses to the tail end of a sensing optical fiber, the sensing pulses and pump pulses have SBS (styrene butadiene styrene) action in the sensing optical fiber, the length of the sensing optical fiber only occupies half of the length of the whole optical fiber (the sensing optical fiber and the guide optical fiber), half of the optical fiber is wasted, and the sensing cost is increased.
In the self-coherent detection Rayleigh Brillouin time domain analysis technology, the SBS action with the pumping pulse is the sensing pulse obtained after the backward Rayleigh scattering of the continuous light, the sensing pulse power obtained after the backward Rayleigh scattering of the continuous light is very low, the sensing distance is limited, and the signal-to-noise ratio of the sensing pulse carrying SBS information obtained after the SBS action is low.
Disclosure of Invention
The embodiment of the invention aims to provide an optical fiber detection method and an optical fiber detection system, so as to ensure the frequency synchronization of sensing pulses and pumping pulses, save optical fibers, reduce the sensing cost, and improve the sensing distance and the signal-to-noise ratio of the sensing pulses carrying SBS information. The specific technical scheme is as follows:
in a first aspect, an embodiment of the present invention provides an optical fiber detection system, where the optical fiber detection system includes: the device comprises a laser, a sensing optical fiber, a first circulator, a second circulator and a collector;
the laser is used for sending a sensing pulse and a pumping pulse to the first circulator, the sending time of the sensing pulse is earlier than that of the pumping pulse, and the time delay between the sensing pulse and the pumping pulse is a sensing pulse width;
the first circulator is used for transmitting the sensing pulse and the pumping pulse through the sensing optical fiber;
the second circulator is used for sending the sensing pulse to the first circulator through the sensing optical fiber after receiving the sensing pulse, so that the sensing pulse and the pumping pulse generate a stimulated Brillouin scattering effect in the sensing optical fiber, and the sensing pulse carrying Brillouin scattering information is obtained;
the first circulator is used for sending the sensing pulse carrying the brillouin scattering information to the collector after receiving the sensing pulse carrying the brillouin scattering information;
and the collector is used for storing the Brillouin scattering information after receiving the sensing pulse carrying the Brillouin scattering information.
Optionally, the optical fiber detection system further includes: an attenuator;
the second circulator is also used for receiving the pumping pulse; sending the pump pulse to the attenuator;
the attenuator is used for attenuating the pumping pulse.
Optionally, the optical fiber detection system further includes: a first filter;
the second circulator is further used for sending the sensing pulse and the pumping pulse to the first filter;
the first filter is used for filtering the sensing pulse and the pumping pulse, sending the pumping pulse to the attenuator and sending the sensing pulse to the second circulator.
Optionally, the second circulator includes four ports;
the second circulator is used for receiving the sensing pulse and the pumping pulse transmitted by the sensing optical fiber through a first port;
the second circulator is used for sending the sensing pulse and the pumping pulse to the first filter through a second port and receiving the pumping pulse sent by the first filter;
the second circulator is used for sending the pumping pulse to the attenuator through a third port;
the second circulator is configured to receive the sensing pulse sent by the first filter through a fourth port, and send the sensing pulse to the first circulator through the first port.
Optionally, the collector includes: the erbium-doped fiber amplifier, the second filter, the photoelectric detector and the acquisition card;
the erbium-doped fiber amplifier is used for amplifying the sensing pulse carrying the Brillouin scattering information to obtain an amplified sensing pulse;
the second filter is used for filtering the amplified sensing pulse to obtain one sideband of the amplified sensing pulse;
the photoelectric detector is used for converting the sideband into an electric signal to obtain an electric signal carrying Brillouin scattering information;
the acquisition card is used for collecting the electric signals carrying the Brillouin scattering information and storing the Brillouin scattering information.
In a second aspect, an embodiment of the present invention further provides an optical fiber detection method, which is applied to an optical fiber detection system, where the optical fiber detection system includes: the device comprises a laser, a sensing optical fiber, a first circulator, a second circulator and a collector; the optical fiber detection method comprises the following steps:
the laser sends a sensing pulse and a pumping pulse to the first circulator, the sending time of the sensing pulse is earlier than that of the pumping pulse, and the time delay between the sensing pulse and the pumping pulse is a sensing pulse width;
the first circulator transmits the sensing pulse and the pumping pulse through the sensing optical fiber;
after receiving the sensing pulse, the second circulator sends the sensing pulse to the first circulator through the sensing optical fiber, so that the sensing pulse and the pumping pulse generate a stimulated Brillouin scattering effect in the sensing optical fiber, and the sensing pulse carrying Brillouin scattering information is obtained;
after receiving the sensing pulse carrying the Brillouin scattering information, the first circulator sends the sensing pulse carrying the Brillouin scattering information to the collector;
and after receiving the sensing pulse carrying the Brillouin scattering information, the collector stores the Brillouin scattering information.
Optionally, the optical fiber detection system further includes an attenuator, and the optical fiber detection method further includes:
the second circulator receives the pump pulse; sending the pump pulse to the attenuator;
the attenuator attenuates the pump pulses.
Optionally, the optical fiber detection system further includes a first filter, and the optical fiber detection method further includes:
the second circulator sends the sensing pulse and the pumping pulse to the first filter;
and the first filter carries out filtering processing on the sensing pulse and the pumping pulse, sends the pumping pulse to the attenuator and sends the sensing pulse to the second circulator.
Optionally, the second circulator includes four ports;
the second circulator receives the sensing pulse and the pumping pulse transmitted by the sensing optical fiber through a first port;
the second circulator sends the sensing pulse and the pumping pulse to the first filter through a second port, and receives the pumping pulse sent by the first filter;
the second circulator sends the pump pulse to the attenuator through a third port;
the second circulator receives the sensing pulse sent by the first filter through a fourth port, and sends the sensing pulse to the first circulator through the first port.
Optionally, the collector includes: the erbium-doped fiber amplifier, the second filter, the photoelectric detector and the acquisition card;
the erbium-doped fiber amplifier amplifies the sensing pulse carrying the Brillouin scattering information to obtain an amplified sensing pulse;
the second filter carries out filtering processing on the amplified sensing pulse to obtain one sideband of the amplified sensing pulse;
the photoelectric detector converts the sideband into an electric signal to obtain an electric signal carrying Brillouin scattering information;
the acquisition card collects the electric signals carrying the Brillouin scattering information and stores the Brillouin scattering information.
According to the optical fiber detection method and system provided by the embodiment of the invention, the sensing pulse is returned to the sensing optical fiber through the second circulator and is used for sending stimulated Brillouin scattering effect with the pumping pulse to obtain Brillouin scattering information, so that temperature or stress information is measured. The frequency synchronization of the sensing pulse and the pumping pulse is ensured by adopting the same laser for transmission, in addition, a guide optical fiber is not required to be introduced, the whole optical fiber can be utilized for detecting temperature, stress information and the like, the optical fiber is saved, and the sensing cost is reduced. In the embodiment of the invention, the sensing pulse is sent to the sensing optical fiber by adopting the second circulator to enable the sensing pulse and the pumping pulse to perform SBS action, wherein the sensing pulse is generated by the laser, and the power of the sensing pulse is larger than that of the sensing pulse obtained after the backward Rayleigh scattering of the continuous light, so that the sensing distance is increased, and the signal-to-noise ratio of the sensing pulse carrying SBS information is increased.
Of course, not all of the advantages described above need to be achieved at the same time in the practice of any one product or method of the invention.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a first block diagram of an optical fiber detection system according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of an optical fiber detection system according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a time domain response of stimulated brillouin scattering according to an embodiment of the present invention;
fig. 4 is a structural diagram of a collector provided in the embodiment of the present invention;
fig. 5 is a schematic diagram of a brillouin gain spectrum of a sensing fiber end according to an embodiment of the present invention;
FIG. 6 is a diagram of a second architecture of a fiber optic detection system according to an embodiment of the present invention;
FIG. 7 is a third block diagram of an optical fiber detection system according to an embodiment of the present invention;
FIG. 8 is a block diagram of a second circulator provided by an embodiment of the invention;
FIG. 9 is a schematic diagram of an optical fiber detection system according to an embodiment of the present invention;
fig. 10 is a flowchart of an optical fiber detection method according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to solve the above problems in the prior art, embodiments of the present invention disclose an optical fiber detection method and system, which are described in detail below.
As shown in fig. 1, fig. 1 is a first architecture diagram of an optical fiber detection system according to an embodiment of the present invention, including: a laser 101, a sensing fiber 102, a first circulator 103, a second circulator 104, and a collector 105.
And the laser 101 is used for sending a sensing pulse and a pumping pulse to the first circulator 103, wherein the sending time of the sensing pulse is earlier than that of the pumping pulse, and the time delay between the sensing pulse and the pumping pulse is the pulse width of the sensing pulse.
As shown in fig. 2, fig. 2 is a schematic diagram of an optical fiber detection system according to an embodiment of the present invention, a pulse width of a sensing pulse is T1, a pulse width of a pump pulse is T2, the sensing pulse is earlier than a transmission time of the pump pulse, and a time delay between the sensing pulse and the pump pulse is a pulse width T1 of one sensing pulse, so that energy loss and pulse deformation caused by overlapping of the sensing pulse and the pump pulse in a time domain are avoided.
In one embodiment, the laser outputs a continuous pulse, the coupler divides the continuous pulse into an upper branch and a lower branch, wherein one branch is a sensing pulse branch, the other branch is a pumping pulse branch, the pulse source firstly modulates the continuous pulse on the sensing pulse branch to obtain a sensing pulse, and the sensing pulse is sent. Delaying the pulse width of a sensing pulse after sending the sensing pulse, modulating continuous pulses on a pump pulse branch to obtain a pump pulse, and sending the pump pulse. Thus, the sending time of the sensing pulse is earlier than that of the pumping pulse, and the time delay between the sensing pulse and the pumping pulse is the pulse width of the sensing pulse.
A first circulator 103 for transmitting the sensing pulse and the pumping pulse through the sensing fiber 102. The first circulator 103 receives the sensing pulse and the pump pulse transmitted by the laser 101, and transmits the sensing pulse and the pump pulse through the sensing fiber 102.
And the second circulator 104 is configured to send the sensing pulse to the first circulator 103 through the sensing optical fiber 102 after receiving the sensing pulse, so that the sensing pulse and the pumping pulse generate a stimulated brillouin scattering effect in the sensing optical fiber 102 to obtain a sensing pulse carrying brillouin scattering information.
As shown in fig. 3, fig. 3 is a schematic diagram of a time domain response of stimulated brillouin scattering provided in an embodiment of the present invention. The abscissa axis represents time in milliseconds (ms), and the ordinate axis represents the amplitude of the sensing pulse in volts (V). In the time between 0ms and 1ms, the Rayleigh scattering signal of the sensing pulse transmitted in the sensing optical fiber returns to reach the front end of the sensing optical fiber and is detected; the sensing pulse meets the pumping pulse within the time of 1ms to 2ms, and the stimulated Brillouin scattering effect is generated; when the time is 2ms, the stimulated Brillouin signal at the tail end of the optical fiber is detected, the sensing pulse leaves the sensing optical fiber, and the amplitude of the sensing pulse is reduced to 0V.
The second circulator 104 receives the sensing pulse transmitted by the sensing fiber 102, and returns the sensing pulse to the sensing fiber 102, so that the sensing pulse and the pumping pulse meet in the sensing fiber 102, and a stimulated brillouin scattering effect is further generated, and the sensing pulse carrying brillouin scattering information is obtained.
The first circulator 103 is configured to receive the sensing pulse carrying the brillouin scattering information, and send the sensing pulse carrying the brillouin scattering information to the collector 105.
The sensing pulse and the pumping pulse generate a stimulated brillouin scattering effect in the sensing optical fiber 102, and after the sensing pulse carrying brillouin scattering information is obtained, the sensing pulse carrying brillouin scattering information is continuously transmitted in the sensing optical fiber 102. The first circulator 103 receives the sensing pulse carrying the brillouin scattering information transmitted by the sensing optical fiber 102, and sends the sensing pulse carrying the brillouin scattering information to the collector 105 for data analysis and processing.
And the collector 105 receives the sensing pulse carrying the brillouin scattering information and stores the brillouin scattering information.
The collector 105 receives the sensing pulse carrying the brillouin scattering information sent by the first circulator 103, performs data processing, and extracts and stores the brillouin scattering information.
In the optical fiber detection system provided by the embodiment of the invention, the sensing pulse is returned to the sensing optical fiber through the second circulator and is used for sending stimulated Brillouin scattering effect with the pumping pulse to obtain Brillouin scattering information, so that temperature or stress information is measured. The frequency synchronization of the sensing pulse and the pumping pulse is ensured by adopting the same laser for transmission, in addition, a guide optical fiber is not required to be introduced, the whole optical fiber can be utilized for detecting temperature, stress information and the like, the optical fiber is saved, and the sensing cost is reduced. In the embodiment of the invention, the sensing pulse is sent to the sensing optical fiber by adopting the second circulator to enable the sensing pulse and the pumping pulse to perform SBS action, wherein the sensing pulse is generated by the laser, and the power of the sensing pulse is larger than that of the sensing pulse obtained after the backward Rayleigh scattering of the continuous light, so that the sensing distance is increased, and the signal-to-noise ratio of the sensing pulse carrying SBS information is increased.
In one embodiment, collector 105 comprises: the erbium-doped fiber amplifier, the second filter, the photoelectric detector and the acquisition card; as shown in fig. 4, fig. 4 is a structural diagram of a collector provided in the embodiment of the present invention.
And the erbium-doped optical fiber amplifier is used for amplifying the sensing pulse carrying the Brillouin scattering information to obtain an amplified sensing pulse.
Because the sensing pulse signal carrying the Brillouin scattering information is weak, the erbium-doped fiber amplifier amplifies the sensing pulse carrying the Brillouin scattering information to obtain the amplified sensing pulse, so that the filtering and data acquisition processing are facilitated.
And the second filter is used for filtering the amplified sensing pulse to obtain one sideband of the amplified sensing pulse.
The amplified sensing pulse is a double-sideband signal, the information contained in the upper sideband and the information contained in the lower sideband of the double sidebands are the same, the second filter carries out filtering processing on the amplified sensing pulse to obtain one sideband of the amplified sensing pulse, so that the frequency band can be saved, and the power of a system and the utilization rate of the frequency band can be improved.
And the photoelectric detector is used for converting the sideband into an electric signal to obtain the electric signal carrying Brillouin scattering information.
One sideband of the amplified sensing pulse is an optical signal, and the photoelectric detector converts the sideband optical signal into an electrical signal to obtain the electrical signal carrying Brillouin scattering information, so that the acquisition card can conveniently acquire and process data.
And the acquisition card is used for collecting the electric signals carrying the Brillouin scattering information and storing the Brillouin scattering information.
The acquisition card collects the electric signals carrying the Brillouin scattering information, performs data analysis processing, extracts the Brillouin scattering information, and stores the Brillouin scattering information.
In an example, as shown in fig. 5, fig. 5 is a schematic diagram of a brillouin gain spectrum at an end of a sensing optical fiber according to an embodiment of the present invention, where a broken line represents a brillouin gain spectrum actually acquired by a sampling card, a smooth curve represents the brillouin gain spectrum after lorentz fitting, an abscissa axis represents brillouin frequency shift in GHz, and an ordinate axis represents an amplitude of a sensing pulse in V. The brillouin gain spectrum is understood here as brillouin scattering information. The Brillouin frequency shift corresponding to the highest point of the Brillouin gain spectrum after Lorentz fitting is 10.999GHz, the Brillouin frequency shift is consistent with the Brillouin frequency shift of 11GHz of the sensing optical fiber, errors can be ignored, and the result of the optical fiber detection system is accurate.
In one embodiment, the optical fiber detection system provided by the present invention further includes an attenuator 106, as shown in fig. 6, and fig. 6 is a second architecture diagram of the optical fiber detection system provided by the embodiment of the present invention.
A second circulator 104 also for receiving pump pulses; the pump pulse is sent to an attenuator.
The second circulator 104 receives the pump pulse transmitted by the sensing fiber 102 and sends the pump pulse to the attenuator 106 to separate the pump pulse from the sensing pulse.
And an attenuator 106 for attenuating the pump pulse.
The attenuator 106 attenuates the pump pulse sent by the second circulator 104, and the pump pulse does not return to the sensing fiber 102 any more, so as to avoid the stimulated brillouin scattering effect of the forward-transmitted pump pulse and the backward-transmitted sensing pulse.
In another embodiment, the optical fiber detection system provided by the present invention further includes an attenuator 106 and a first filter 107, as shown in fig. 7, and fig. 7 is a third architecture diagram of the optical fiber detection system provided by the embodiment of the present invention.
The second circulator 104 is also used to send the sensing pulses and the pumping pulses to the first filter.
The second circulator 104 sends the sensing pulses and the pumping pulses to a first filter 107 for filtering separation.
The first filter 107 is used to filter the sensing pulses and the pump pulses, send the pump pulses to the attenuator 106, and send the sensing pulses to the second circulator 104.
The first filter 107 filters the sensing pulses and the pump pulses transmitted from the second circulator 104 according to wavelength to separate the pump pulses from the sensing pulses, the sensing pulses are transmitted to the second circulator 104 through the first filter 107, and the pump pulses are transmitted to the attenuator 106 through the first filter 107 to be attenuated.
And an attenuator 106 for attenuating the pump pulse.
The attenuator 106 receives the pump pulse transmitted from the first filter 107 and attenuates the pump pulse. The pump pulses do not return to the sensing fiber 102, and the stimulated brillouin scattering effect of the pump pulses in forward transmission and the sensing pulses in reverse transmission is avoided.
In one embodiment of the present invention, the second circulator 104, includes four ports; as shown in fig. 8, fig. 8 is a structural view of a second circulator provided in an embodiment of the present invention.
The second circulator is used for receiving the sensing pulse and the pumping pulse transmitted by the sensing optical fiber through the first port;
the second circulator is used for sending the sensing pulse and the pumping pulse to the first filter through the second port and receiving the pumping pulse sent by the first filter;
a second circulator for transmitting the pump pulse to the attenuator through a third port;
and the second circulator is used for receiving the sensing pulse sent by the first filter through the fourth port and sending the sensing pulse to the first circulator through the first port.
In one embodiment, as shown in fig. 9, fig. 9 is a schematic diagram of an optical fiber detection system according to an embodiment of the present invention. The laser outputs a 1550nm continuous pulse, which is divided into an upper branch and a lower branch by a 90:10 coupler. On a sensing pulse branch, a radio frequency signal generated by a microwave source drives an electro-optic modulator, bias voltage of the electro-optic modulator is adjusted to perform double-sideband modulation for inhibiting carrier waves on continuous pulses on the sensing pulse branch, continuous pulses of double sidebands are obtained, the pulse source generates electric pulses with the pulse width of 1ms to drive an optical switch, the continuous pulses of the double sidebands are modulated into optical pulses of the double sidebands with the pulse width of 1ms, polarization noise in the optical pulses of the double sidebands with the pulse width of 1ms is eliminated by a polarization switch, and sensing pulses with the pulse width of 1ms are obtained. On a pumping pulse branch, a pulse source generates an electric pulse with the pulse width of 20ns, the electric pulse on a sensing pulse branch is delayed for 1ms relative to the electric pulse on the sensing pulse branch to be transmitted, a semiconductor optical amplifier is driven to modulate continuous pulses on the pumping pulse branch into optical pulses with the pulse width of 20ns, an erbium-doped optical fiber amplifier 1 amplifies the optical pulses with the pulse width of 20ns to obtain pumping pulses with the pulse width of 20ns, the sensing pulses and the pumping pulses pass through a 50:50 coupler and then enter a sensing optical fiber through a circulator 1, the sensing optical fiber transmits the sensing pulses and the pumping pulses, the sensing pulses and the pumping pulses enter a circulator 2 through a first port of the circulator 2 and enter a first filter through a second port of the circulator 2, the first filter filters and separates the sensing pulses with long wavelength and the pumping pulses according to the wavelength, the sensing pulses are low-frequency short-wavelength, and the pumping pulses are high-frequency, the first filter can be a band-pass filter, the pass band is set as the wavelength of the sensing pulse in advance, only the sensing pulse is allowed to pass through, so the pumping pulse returns to the circulator 2 and enters the attenuator through the third port of the circulator 2 for attenuation processing, the sensing pulse enters the fourth port of the circulator 2 through the first filter and returns to the sensing fiber from the first port, the sensing pulse and the pumping pulse transmitted in the forward direction in the sensing fiber are subjected to stimulated Brillouin scattering action to obtain the sensing pulse carrying Brillouin scattering information, the sensing pulse carrying the Brillouin scattering information enters the erbium-doped fiber amplifier 2 through the circulator 1 for amplification processing to obtain the amplified sensing pulse, the second filter carries out filtering processing on the amplified sensing pulse to obtain one sideband of the amplified sensing pulse, and the photoelectric detector converts the sideband into an electric signal carrying the Brillouin scattering information, the acquisition card collects and stores Brillouin scattering information.
Corresponding to the embodiment of the optical fiber detection system, the embodiment of the present invention further provides an optical fiber detection method, as shown in fig. 10, and fig. 10 is a flowchart of the optical fiber detection method provided in the embodiment of the present invention. The optical fiber detection method can be applied to an optical fiber detection system, and the optical fiber detection system comprises: the device comprises a laser, a sensing optical fiber, a first circulator, a second circulator and a collector. The optical fiber detection method comprises the following steps.
At step 1002, a first circulator transmits a sensing pulse and a pumping pulse through a sensing fiber.
And 1003, after receiving the sensing pulse, the second circulator sends the sensing pulse to the first circulator through the sensing optical fiber, so that the sensing pulse and the pumping pulse generate a stimulated brillouin scattering effect in the sensing optical fiber, and the sensing pulse carrying brillouin scattering information is obtained.
And step 1004, after receiving the sensing pulse carrying the brillouin scattering information, the first circulator sends the sensing pulse carrying the brillouin scattering information to the collector.
And 1005, after receiving the sensing pulse carrying the brillouin scattering information, the collector stores the brillouin scattering information.
In one embodiment, the collector includes: the erbium-doped fiber amplifier, the second filter, the photoelectric detector and the acquisition card;
the erbium-doped fiber amplifier amplifies the sensing pulse carrying the Brillouin scattering information to obtain an amplified sensing pulse;
the second filter carries out filtering processing on the amplified sensing pulse to obtain one sideband of the amplified sensing pulse;
the photoelectric detector converts the sideband into an electric signal to obtain an electric signal carrying Brillouin scattering information;
the acquisition card collects the electric signals carrying the Brillouin scattering information and stores the Brillouin scattering information.
In one embodiment, the optical fiber detection system further includes an attenuator, and the optical fiber detection method further includes:
the second circulator receives the pumping pulse; sending the pump pulse to an attenuator;
the attenuator attenuates the pump pulses.
In another embodiment, the optical fiber detection system further includes a first filter and an attenuator, and the optical fiber detection method further includes:
the second circulator sends the sensing pulse and the pumping pulse to the first filter;
the first filter carries out filtering processing on the sensing pulse and the pumping pulse, sends the pumping pulse to the attenuator, and sends the sensing pulse to the second circulator.
In one embodiment, the second circulator includes four ports;
the second circulator receives sensing pulses and pumping pulses transmitted by the sensing optical fiber through the first port;
the second circulator sends sensing pulses and pumping pulses to the first filter through the second port and receives the pumping pulses sent by the first filter;
the second circulator sends a pumping pulse to the attenuator through a third port;
the second circulator receives the sensing pulse sent by the first filter through the fourth port and sends the sensing pulse to the first circulator through the first port.
In the optical fiber detection system provided by the embodiment of the invention, the sensing pulse is returned to the sensing optical fiber through the second circulator and is used for sending stimulated Brillouin scattering effect with the pumping pulse to obtain Brillouin scattering information, so that temperature or stress information is measured. The frequency synchronization of the sensing pulse and the pumping pulse is ensured by adopting the same laser for transmission, in addition, a guide optical fiber is not required to be introduced, the whole optical fiber can be utilized for detecting temperature, stress information and the like, the optical fiber is saved, and the sensing cost is reduced. In the embodiment of the invention, the sensing pulse is sent to the sensing optical fiber by adopting the second circulator to enable the sensing pulse and the pumping pulse to perform SBS action, wherein the sensing pulse is generated by the laser, and the power of the sensing pulse is larger than that of the sensing pulse obtained after the backward Rayleigh scattering of the continuous light, so that the sensing distance is increased, and the signal-to-noise ratio of the sensing pulse carrying SBS information is increased.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
All the embodiments in the present specification are described in a related manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, as for the method embodiment, since it is substantially similar to the system embodiment, the description is simple, and the relevant points can be referred to the partial description of the system embodiment.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.
Claims (8)
1. An optical fiber detection system, comprising: the device comprises a laser, a sensing optical fiber, a first circulator, a second circulator and a collector;
the laser is used for sending a sensing pulse and a pumping pulse to the first circulator, the sending time of the sensing pulse is earlier than that of the pumping pulse, and the time delay between the sensing pulse and the pumping pulse is a sensing pulse width;
the first circulator is used for transmitting the sensing pulse and the pumping pulse through the sensing optical fiber;
the second circulator is used for sending the sensing pulse to the first circulator through the sensing optical fiber after receiving the sensing pulse, so that the sensing pulse and the pumping pulse generate a stimulated Brillouin scattering effect in the sensing optical fiber, and the sensing pulse carrying Brillouin scattering information is obtained;
the first circulator is used for sending the sensing pulse carrying the brillouin scattering information to the collector after receiving the sensing pulse carrying the brillouin scattering information;
the collector is used for storing the Brillouin scattering information after receiving the sensing pulse carrying the Brillouin scattering information;
the optical fiber detection system further comprises: an attenuator;
the second circulator is also used for receiving the pumping pulse; sending the pump pulse to the attenuator;
the attenuator is used for attenuating the pumping pulse.
2. The system of claim 1, wherein the fiber optic detection system further comprises: a first filter;
the second circulator is further used for sending the sensing pulse and the pumping pulse to the first filter;
the first filter is used for filtering the sensing pulse and the pumping pulse, sending the pumping pulse to the attenuator and sending the sensing pulse to the second circulator.
3. The system of claim 2, wherein the second circulator comprises four ports;
the second circulator is used for receiving the sensing pulse and the pumping pulse transmitted by the sensing optical fiber through a first port;
the second circulator is used for sending the sensing pulse and the pumping pulse to the first filter through a second port and receiving the pumping pulse sent by the first filter;
the second circulator is used for sending the pumping pulse to the attenuator through a third port;
the second circulator is configured to receive the sensing pulse sent by the first filter through a fourth port, and send the sensing pulse to the first circulator through the first port.
4. The system of claim 1, wherein the collector comprises: the erbium-doped fiber amplifier, the second filter, the photoelectric detector and the acquisition card;
the erbium-doped fiber amplifier is used for amplifying the sensing pulse carrying the Brillouin scattering information to obtain an amplified sensing pulse;
the second filter is used for filtering the amplified sensing pulse to obtain one sideband of the amplified sensing pulse;
the photoelectric detector is used for converting the sideband into an electric signal to obtain an electric signal carrying Brillouin scattering information;
the acquisition card is used for collecting the electric signals carrying the Brillouin scattering information and storing the Brillouin scattering information.
5. An optical fiber detection method is applied to an optical fiber detection system, and the optical fiber detection system comprises: the device comprises a laser, a sensing optical fiber, a first circulator, a second circulator and a collector; the optical fiber detection method comprises the following steps:
the laser sends a sensing pulse and a pumping pulse to the first circulator, the sending time of the sensing pulse is earlier than that of the pumping pulse, and the time delay between the sensing pulse and the pumping pulse is a sensing pulse width;
the first circulator transmits the sensing pulse and the pumping pulse through the sensing optical fiber;
after receiving the sensing pulse, the second circulator sends the sensing pulse to the first circulator through the sensing optical fiber, so that the sensing pulse and the pumping pulse generate a stimulated Brillouin scattering effect in the sensing optical fiber, and the sensing pulse carrying Brillouin scattering information is obtained;
after receiving the sensing pulse carrying the Brillouin scattering information, the first circulator sends the sensing pulse carrying the Brillouin scattering information to the collector;
after the collector receives the sensing pulse carrying the Brillouin scattering information, the Brillouin scattering information is stored;
the optical fiber detection system further comprises an attenuator, and the optical fiber detection method further comprises the following steps:
the second circulator receives the pump pulse; sending the pump pulse to the attenuator;
the attenuator attenuates the pump pulses.
6. The method of claim 5, wherein the fiber optic detection system further comprises a first filter, the fiber optic detection method further comprising:
the second circulator sends the sensing pulse and the pumping pulse to the first filter;
and the first filter carries out filtering processing on the sensing pulse and the pumping pulse, sends the pumping pulse to the attenuator and sends the sensing pulse to the second circulator.
7. The method of claim 6, wherein the second circulator comprises four ports;
the second circulator receives the sensing pulse and the pumping pulse transmitted by the sensing optical fiber through a first port;
the second circulator sends the sensing pulse and the pumping pulse to the first filter through a second port, and receives the pumping pulse sent by the first filter;
the second circulator sends the pump pulse to the attenuator through a third port;
the second circulator receives the sensing pulse sent by the first filter through a fourth port, and sends the sensing pulse to the first circulator through the first port.
8. The method of claim 5, wherein the collector comprises: the erbium-doped fiber amplifier, the second filter, the photoelectric detector and the acquisition card;
the erbium-doped fiber amplifier amplifies the sensing pulse carrying the Brillouin scattering information to obtain an amplified sensing pulse;
the second filter carries out filtering processing on the amplified sensing pulse to obtain one sideband of the amplified sensing pulse;
the photoelectric detector converts the sideband into an electric signal to obtain an electric signal carrying Brillouin scattering information;
the acquisition card collects the electric signals carrying the Brillouin scattering information and stores the Brillouin scattering information.
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