CN212030564U - Light source frequency shift calibration auxiliary channel structure and optical fiber vibration measuring device - Google Patents
Light source frequency shift calibration auxiliary channel structure and optical fiber vibration measuring device Download PDFInfo
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Abstract
The utility model provides a light source frequency shift calibration auxiliary channel structure and an optical fiber vibration measuring device, which relate to the field of optical fiber distributed vibration measurement and comprise a laser, a splitter, an interferometer, a photoelectric balance detector and an arithmetic unit which are electrically connected in sequence; the laser and the splitter, the splitter and the interferometer are connected by optical fibers, the interferometer, the photoelectric balance detector and the arithmetic unit form an auxiliary channel for acquiring the continuous light output by the laser and calculating the frequency shift electric signal of the output continuous light, and the measurement is carried out by the traditional phase-sensitive optical time domain reflection measurementIn the measuring device, a frequency shift calibration auxiliary channel is additionally used as
The auxiliary channel of the measuring device is used for completely compensating the frequency drift of the light source, eliminating the phase noise of the laser and improving the measuring precision of the external vibration signal.
Description
Technical Field
The disclosure relates to the field of optical fiber distributed vibration measurement, in particular to a light source frequency shift calibration auxiliary channel structure and an optical fiber vibration measurement device.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
The optical time domain reflection measurement technology is an essential technology in optical cable construction, maintenance and monitoring, and is based on the principle of backward scattering and Fresnel reverse of light, and utilizes the backward scattering light wave generated when pulse light wave propagates in an optical fiber to obtain the information of energy (amplitude) attenuation, so that the optical time domain reflection measurement technology can be used for measuring the optical fiber attenuation, joint loss, optical fiber fault point positioning, knowing the loss distribution condition of the optical fiber along the length and the like.
With the continuous improvement of measurement techniques, phase-sensitive optical time-domain reflectometry, for example, has emerged
The technology,
Vibration measurement technique and based on quadratic difference
A method of measurement;
the inventors found that
For a system, the phase noise of the laser may reduce the measurement accuracy of the system and the spatial resolution of the system. Therefore, it is important to improve the phase noise of the optical wave. On one hand, the stability of the optical wave frequency can be improved and the phase noise can be reduced by improving the laser material, keeping the environmental temperature and humidity and the atmospheric pressure stable and the like; however, on the basis of the existing laser manufacturing process and constant temperature, humidity and pressure processing technology, the technology is not a technical method which is easy to realize in a short period of time; on the other hand, the adverse effects of the optical wave phase noise on the vibration measurement accuracy and the spatial positioning can be suppressed by designing a new optical path structure and a data processing method, such as quadratic difference-based, for a digital signal processing method
The measurement method is limited by the effective bit (quantization noise) of the data acquisition card, and the digital signal processing method is only used for not reducing the phase noise of the laser at all, so that the measurement precision of the external vibration signal is difficult to further improve.
Disclosure of Invention
The present disclosure is directed to provide a light source frequency shift calibration auxiliary channel structure and an optical fiber vibration measurement device, which are configured to increase the use of a frequency shift calibration auxiliary channel in a conventional phase-sensitive optical time domain reflectometry measurement device
Auxiliary channel of measuring device, pairThe frequency drift of the light source is completely compensated, the phase noise of the laser is eliminated, and the measurement precision of an external vibration signal is improved.
The first purpose of the present disclosure is to provide a light source frequency shift calibration auxiliary channel structure, which adopts the following technical solutions:
the device comprises a laser, a branching unit, an interferometer, a photoelectric balance detector and an arithmetic unit which are electrically connected in sequence; the laser and the splitter as well as the splitter and the interferometer are connected through optical fibers, and the interferometer, the photoelectric balance detector and the arithmetic unit form an auxiliary channel for acquiring continuous light output by the laser and calculating a frequency offset electric signal of the output continuous light.
Furthermore, the input end of the branching unit is connected with the laser, and the output end of the branching unit is connected with the interferometer.
Furthermore, the interferometer comprises a coupler and an optical mixer, wherein the coupler is connected with the optical mixer through two paths of optical fibers.
Furthermore, the photoelectric balance detector comprises a first photoelectric balance detector and a second photoelectric balance detector which are respectively connected with the optical mixer and the arithmetic unit.
Furthermore, the input end of the coupler is connected with the output end of the shunt, and one output end of the coupler is sequentially connected with the optical mixer, the first photoelectric balance detector and the arithmetic unit; the other output end is connected with the optical mixer, the second photoelectric balance detector and the arithmetic unit in sequence.
Furthermore, a delay optical fiber is connected in series on one optical fiber between the coupler and the optical mixer.
Further, the optical mixer is a 90-degree optical mixer, and the coupler is configured to input two orthogonal optical signals to the optical mixer.
Furthermore, the arithmetic unit comprises a first averager, a second averager, a first multiplier, a second multiplier and an adder, wherein one output end of the first photoelectric balance detector is sequentially connected with the first averager, the first multiplier and the adder, the other output end of the first photoelectric balance detector is sequentially connected with the first multiplier and the adder, one output end of the second photoelectric balance detector is sequentially connected with the second averager, the second multiplier and the adder, and the other output end of the second photoelectric balance detector is sequentially connected with the second multiplier and the adder.
The second purpose of the present disclosure is to provide an optical fiber vibration measurement apparatus, which adopts the following technical solutions:
comprises that
Measuring device and light source frequency shift calibration auxiliary channel structure, splitter and
the measuring device is connected.
Further, the output end of the arithmetic unit is connected with
A data acquisition card of the measuring device.
Compared with the prior art, the utility model has the advantages and positive effects that:
(1) using frequency-shifted calibration auxiliary channels as
The auxiliary channel of the measuring device is used for completely compensating the frequency drift of the light source, eliminating the phase noise of the laser and further improving the measuring precision of the external vibration signal;
(2) in a feedforward loop of a light source noise suppression feedforward structure, two mutually orthogonal interference optical signals are obtained based on an interferometer and a 90-degree optical mixer and are respectively output to a photoelectric balance detector 1 and a photoelectric balance detector 2 to be converted into two interference electrical signals; the influence of the random change of the initial phase of the optical frequency on the measurement result when the optical frequency drift amount is measured based on the single-path signal is avoided, and the measurement precision of the optical frequency drift is improved, so that the suppression of the phase noise of the light source is facilitated, and the measurement precision of the external vibration signal is improved.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure and are not to limit the disclosure.
Fig. 1 is a schematic diagram of a structure and a flow of optical fiber vibration measurement in embodiments 1 and 2 of the present disclosure;
fig. 2 is a structural diagram of an auxiliary channel in embodiments 1 and 2 of the present disclosure.
Detailed Description
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present disclosure. As used herein, the singular forms "a", "an", and/or "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof;
for convenience of description, the words "up", "down", "left" and "right" in this disclosure, if any, merely indicate that the directions of movement are consistent with those of the figures themselves, and are not limiting in structure, but merely facilitate the description of the invention and simplify the description, rather than indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present disclosure.
As described in the background, the prior art is twice differenced
The measuring method is a digital signal processing method, is restricted by the effective bit (quantization noise) of a data acquisition card, does not reduce the phase noise of a laser at all, and is difficult to further improve the measuring precision of an external vibration signal; to the aboveIn order to solve the problems, the present disclosure provides a light source frequency shift calibration auxiliary channel structure and an optical fiber vibration measurement device.
Light source noise: the linewidth of the laser cannot be infinitely narrow and there is always some phase noise (otherwise known as "frequency drift"). When pulsed light is transmitted in an optical fiber, the intensity of a backward Rayleigh scattering signal is affected by phase noise of the detected light to generate jitter, so that the signal-to-noise ratio of a measurement signal is reduced, and positioning and measurement errors of a measured vibration signal even fail.
To pair
For a system, the phase noise of the laser may reduce the measurement accuracy of the system and the spatial resolution of the system. Therefore, it is important to improve the phase noise of the optical wave. On one hand, the stability of the optical wave frequency can be improved and the phase noise can be reduced by improving the laser material, keeping the environmental temperature and humidity and the atmospheric pressure stable and the like; on the other hand, the adverse effects of the optical wave phase noise on the vibration measurement precision and the space positioning can be inhibited by designing a new optical path structure and a new data processing method.
For the former, on the basis of the existing laser manufacturing process and constant temperature, humidity and pressure treatment technology, the technology is not a technical method which is easy to realize in a short period; for the latter, a more general method is to use a quadratic difference method, which is an improved method of pure digital signal processing.
Based on quadratic difference
The detailed working principle of the measuring method is as follows:
in the classic
On the basis of the system structure, continuous light emitted by a narrow linewidth laser is divided into two paths through a coupler with a specific power ratio, wherein one path of continuous light passes through an acousto-optic modulator (Acous) with a frequency shift functionAn Optical Amplifier (generally, Erbium Doped Fiber Amplifier (EDFA)) performs power compensation, enters a port of the circulator 1, exits through a port of the circulator 3, enters a sensing Fiber, acquires vibration measurement information along the Fiber, and generates backward rayleigh scattered light carrying environmental vibration information, which passes through the port of the circulator 3 again and exits from a port of the circulator 2.
The other path of continuous light which is branched after the continuous light emitted by the light source passes through the coupler with the specific power ratio is used as local reference light. The local reference light and the backward Rayleigh scattered light emitted from the port 2 of the circulator generate coherent signals through a coupler with the ratio of 50:50, the coherent signals are converted into electric signals through a photoelectric detector and enter a data acquisition card, digital signals are obtained, data processing is carried out on the electric signals, and environmental vibration information along the optical fiber is obtained.
However, based on quadratic differences
The measuring method is a digital signal processing method, does not reduce the phase noise of the laser at all, and does not consider the feasible scheme of improving and suppressing the phase noise of the measurement by the optical path structure.
Example 1
In an exemplary embodiment of the present disclosure, as shown in fig. 1-2, a light source frequency shift calibration auxiliary channel structure is proposed.
The light source frequency shift calibration auxiliary channel structure comprises: laser, splitter, frequency shift calibration auxiliary channel.
The laser emits continuous light with narrow linewidth, the continuous light is divided into 3 paths through a splitter, one path of the continuous light is used as calibration light, the calibration light enters a frequency shift calibration auxiliary channel, a light source frequency shift electric signal is obtained, and the light source frequency shift electric signal is transmitted to a data acquisition card.
The frequency shift calibration auxiliary channel comprises: the optical fiber delay line comprises a coupler 2, a delay optical fiber, a 90-degree optical mixer, a photoelectric balance detector 1, a photoelectric balance detector 2, an averager 1, an averager 2, a multiplier 1, a multiplier 2 and an adder.
The 3 rd path of continuous light output by the coupler 1 entering the frequency shift calibration auxiliary channel is divided into two paths by the coupler 2 with the ratio of 50:50, wherein one path of continuous light directly enters the 90-degree optical mixer, and the other path of continuous light enters the 90-degree optical mixer through the delay optical fiber. The coupler 2, the transmission fiber without delay fiber, the transmission fiber with delay fiber, and the 90-degree optical mixer constitute a classical mach-zehnder fiber optic interferometer, with the difference in arm length determined by the delay fiber. Based on the Mach-Zehnder optical fiber interferometer, the 90-degree optical mixer obtains two mutually orthogonal interference optical signals, and the two mutually orthogonal interference optical signals are respectively output to the photoelectric balance detector 1(I path) and the photoelectric balance detector 2(Q path) and converted into two interference electric signals. The I path interference electric signal and the Q path interference electric signal respectively pass through the averager 1 and the averager 2, and simultaneously enter the multiplier 1 and the multiplier 2 together with the I path original signal and the Q path original signal, the two multipliers are output to the adder, and the two paths of signals are added and then transmitted to the data acquisition card.
The data acquisition card converts the two paths of input electric signals into digital signals and transmits the digital signals to the processor.
Among them, for the selection of each element, a set of examples is given in the present embodiment:
a laser: a Distributed Feedback (DFB) laser (model: DFB-1550-DM-4);
a splitter: 1X3 optical splitter;
a photoelectric detector: FC/APC PIN photodetectors;
a data acquisition card: high speed data acquisition card (model PCI 9812);
a processor: a core board based on EP4CE30F FPGA;
the coupler 2: a standard single mode fiber coupler with a splitting ratio of 50: 50;
delay fiber: the method is manufactured by using a Corning SMF-28 single-mode fiber;
90-degree optical mixer: a single-stage polarization 90-degree optical mixer (model COH 24X);
averager 1: an operational amplifier AD8065 is used for building an integrating circuit;
an averager 2: an operational amplifier AD8065 is used for building an integrating circuit;
a multiplier 1: building based on an analog multiplier chip AD 835;
and a multiplier 2: building based on an analog multiplier chip AD 835;
an adder: the adder circuit was built using 3 operational amplifiers AD 8065.
It is understood that the above-mentioned selection can be adjusted according to actual requirements.
According to the frequency shift calibration auxiliary signal, further light source frequency drift compensation is carried out on the measurement signal, the influence of the light source frequency drift on the measurement signal is completely eliminated, and the measurement precision of the external vibration signal is improved.
Example 2
In another exemplary embodiment of the present disclosure, as shown in fig. 1-2, an optical fiber vibration measuring device is provided.
The device mainly comprises an acousto-optic modulator, an optical amplifier, a circulator, a sensing optical fiber, a data acquisition card, a processor and the light source frequency shift calibration auxiliary channel structure as described in embodiment 1.
Laser outgoing narrow linewidth continuous light is divided into 3 ways through the branching unit, wherein 1 way continuous light is converted into pulse light with specific width and period through the acousto-optic modulator with the frequency shift function, the pulse light enters the port 1 of the circulator after being subjected to power compensation through the optical amplifier, the continuous light enters the sensing optical fiber through the outgoing port 3 of the circulator, vibration measurement information along the optical fiber is obtained, backward Rayleigh scattering light which is generated in the sensing optical fiber and carries environmental vibration information passes through the port 3 of the circulator again, and the backward Rayleigh scattering light is emitted from the port 2 of the circulator.
And the 2 nd path of continuous light split after the continuous light emitted by the light source passes through the splitter is used as local reference light. The local reference light and the backward Rayleigh scattered light emitted from the port of the circulator 2 generate coherent signals through the coupler 1 in a ratio of 50:50, the coherent signals are converted into electric signals through the photoelectric detector, the electric signals enter the data acquisition card, the electric signals are converted into digital signals, the digital signals are sent to the processor for data processing, and the environmental vibration information along the optical fiber is acquired.
And the 3 rd path of continuous light which is divided after the continuous light emitted by the light source passes through the splitter is used as calibration light, enters a frequency shift calibration auxiliary channel to obtain a light source frequency shift electric signal, and is transmitted to a data acquisition card.
In the present embodiment, a set of examples of the selection of the elements is given:
an acousto-optic modulator: an acousto-optic modulator (model M080-1 x-GHx);
an optical amplifier: an erbium doped fiber amplifier (model AMP-PM 15M);
a circulator: a 3-port fiber optic circulator (model MCCIR-1550);
the coupler 1: a standard single mode fiber coupler with a splitting ratio of 50: 50;
a photoelectric detector: FC/APC PIN photodetectors;
a data acquisition card: high speed data acquisition card (model PCI 9812);
a processor: core board based on EP4CE30F FPGA.
It is understood that the above-mentioned selection can be adjusted according to actual requirements.
The data acquisition card converts the two paths of input electric signals into digital signals and transmits the digital signals to the processor. The processor performs Hilbert transform on the Rayleigh scattering coherent signal containing the vibration information along the optical fiber environment, and extracts phase information; and one point is selected before and after the vibration point for single phase difference, so that phase noise caused by different initial phases of Rayleigh scattering light and local reference light is eliminated, and the influence of frequency drift of a light source on a measurement signal is reduced.
According to the frequency shift calibration auxiliary signal, further light source frequency drift compensation is carried out on the measurement signal, the influence of the light source frequency drift on the measurement signal is completely eliminated, and the measurement precision of the external vibration signal is improved.
Example 3
In yet another exemplary embodiment of the present disclosure, as shown in fig. 1-2, a method for operating an optical fiber vibration measurement device is provided.
The method comprises the following steps:
the laser outputs continuous light at a frequency v0+Δv0(t)，v0Represents the ideal value of the optical wave frequency, is constant, but because the laser has noise inevitably, the optical wave frequency contains a frequency drift component Deltav0(t), t represents time；
The continuous light of the laser is divided into 3 paths by a splitter, wherein the 1 st path of continuous light is converted into pulse light with specific width and period by an acousto-optic modulator with frequency shift function, and then enters a sensing optical fiber by an optical amplifier and a circulator to obtain Rayleigh scattering light wave Er(zi,t)，ziIndicating the position of the sensing optical fiber where Rayleigh scattering occurs;
the 2 nd path continuous light is used as local reference light Eref(zref,t)，zrefA length of optical fiber representing a reference path;
the Rayleigh scattered light and the local reference light enter the photoelectric detector after interfering in the coupler, and the signal is represented as I (z)i,t)；
Frequency reduction processing is carried out on the interference signal by taking the frequency offset of the acousto-optic modulator as reference, and then phase information in the interference signal is extracted by using a Hilbert transform and anti-tangent method
Step 4, selecting the position z behind the vibration pointAAnd z is the front position of the vibration pointBThe phase difference between the A, B points is obtained to obtain the single difference phase
Wherein D isABIndicating A, B the spacing between the two points,
representing the phase change introduced by the external vibration signal;
phase noise caused by different initial phases of Rayleigh scattering light and local reference light is eliminated;
and, the single differential phase shifts the influence of the light source frequency drift on the measurement signal, from
ReduceTo
Continuous light emitted by a light source is divided into a 3 rd path of continuous light serving as calibration light after passing through a splitter, enters a frequency shift calibration auxiliary channel, and is subjected to a classical Mach-Zehnder interferometer to obtain two paths (an I path and a Q path) of orthogonal interference signals;
the I path interference signal is multiplied by the I path original signal after being subjected to time averaging, and the Q path interference signal is multiplied by the Q path original signal after being subjected to time averaging;
then adding the two obtained signals by using an adder;
performing Hilbert transform and arc tangent operation on the signal output by the adder to extract phase information
Wherein the content of the first and second substances,
representing the length difference of an interference arm of a Mach-Zehnder interferometer in the frequency shift calibration auxiliary channel;
a, B according to the distance D between two points in single differenceABAnd the difference D in the length of the interference arms of the Mach-Zehnder interferometer in the sum-frequency-shift calibration auxiliary channelDIFProportional relationship therebetween, determining frequency drift correction coefficient
The frequency drift calibration is carried out on the single differential phase to obtain the external vibration signal measured value with higher precision
Specifically, in this embodiment, the measurement method includes the following steps:
step 1, the laser outputs continuous light with the wavelength of 1550nm or 1330 nm:
E(t)＝Acos(2π(ν0+Δv0(t))t) (1)
wherein A represents the amplitude of light waves, v0Represents the ideal value of the optical wave frequency, and is constant 193.5THz (corresponding to 1550nm wavelength) or 229.0THz (corresponding to 1310nm wavelength), but because the laser has inevitable noise, the optical wave frequency contains frequency drift component Deltav0(t), t represents time.
And 2, dividing the laser continuous light into 3 paths through a splitter, wherein the 1 st path of continuous light is converted into pulse light with specific width and period through an acousto-optic modulator with a frequency shift function, and then enters a sensing optical fiber through an optical amplifier and a circulator to obtain Rayleigh scattering light waves:
wherein B represents the Rayleigh scattered light wave amplitude, ziIndicating the position of the sensing fiber where rayleigh scattering occurs,
representing the number of light waves, k can be regarded as consisting of v only, since the frequency shift component of the light wave of the light source is small compared to the speed of light c0Determining, n represents the refractive index of the optical fiber, c represents the speed of light, fplusRepresenting the pulse frequency, fAOMIndicating the amount of frequency offset of the acousto-optic modulator,
representing a phase change, theta, introduced by an external vibration signalrRepresenting the initial phase of the rayleigh scattered light.
And the 2 nd path of continuous light is used as local reference light:
Eref(zref，t)＝B cos(kzref-2π(v0+Δv0(t))t+θref) (3)
wherein, B represents the amplitude of the reference light wave, the amplitude of the reference light wave is equal to the amplitude of the Rayleigh scattering light wave by adjusting the splitting ratio of the splitter, and z isrefThe length of the optical fiber, theta, representing the reference pathrefIndicating the initial phase of the local reference light.
The rayleigh scattered light and the local reference light enter the photodetector after interfering in the coupler, and the signal can be expressed as:
and 3, performing frequency reduction processing on the interference signal by taking the frequency offset of the acousto-optic modulator as a reference, and extracting phase information in the interference signal by using a Hilbert transform and an anti-tangent method:
step 4, selecting the position z behind the vibration pointAAnd z is the front position of the vibration pointBAnd (4) subtracting the phases of the A, B points to obtain a single differential phase:
wherein D isABIndicating A, B the separation of the two points. Compared with the step 3, the step 4 eliminates phase noise caused by the difference of the initial phases of Rayleigh scattering light and local reference light.
Due to the fact that
The device only focuses on the measurement of the alternating current vibration signal, and can ignore the direct current component v of the light wave frequency0Induced phase constants, retaining only the AC component Δ ν0(t) induced phase noise. And, the single differential phase shifts the light source frequencyInfluence of shift on the measurement signal, from
Reduced to
And 5, taking the 3 rd path of continuous light which is split after the continuous light emitted by the light source passes through the splitter as calibration light, entering a frequency shift calibration auxiliary channel, and obtaining two paths (I path and Q path) of orthogonal interference signals by using a classical Mach-Zehnder interferometer:
I(t)＝C cos(2π(v0+Δv0(t))τ) (7)
Q(t)＝C sin(2π(v0+Δv0(t))τ) (8)
where C represents the amplitude of the interference signal and τ represents the time delay caused by the interferometer arm length of the mach-zehnder interferometer.
The I path interference signal is multiplied by the I path original signal after being subjected to time averaging, and the Q path interference signal is multiplied by the Q path original signal after being subjected to time averaging to obtain:
where T represents the length of time for averaging. The phase noise caused by the frequency drift of the light source is a bounded zero mean value random process, and is zero after time averaging, so that the following results are obtained:
adding the two paths of signals obtained in the previous step to obtain:
performing Hilbert transform and arc tangent operation on the signal output by the adder, and extracting phase information:
A, B according to the distance D between two points in single differenceABAnd the difference D in the length of the interference arms of the Mach-Zehnder interferometer in the sum-frequency-shift calibration auxiliary channelDIFProportional relationship therebetween, determining frequency drift correction coefficient
And (3) carrying out frequency drift calibration on the single differential phase to obtain an external vibration signal measured value with higher precision:
the above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure, and various modifications and changes may be made to the present disclosure by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present disclosure should be included in the protection scope of the present disclosure.
Claims (10)
1. A light source frequency shift calibration auxiliary channel structure is characterized by comprising a laser, a branching unit, an interferometer, a photoelectric balance detector and an arithmetic unit, wherein the interferometer, the photoelectric balance detector and the arithmetic unit are sequentially and electrically connected; the laser and the splitter as well as the splitter and the interferometer are connected through optical fibers, and the interferometer, the photoelectric balance detector and the arithmetic unit form an auxiliary channel for acquiring continuous light output by the laser and calculating a frequency offset electric signal of the output continuous light.
2. The light source frequency shift calibration auxiliary channel structure as claimed in claim 1, wherein said splitter has an input connected to a laser and an output connected to an interferometer.
3. The optical source frequency-shift calibration auxiliary channel structure of claim 1, wherein the interferometer comprises a coupler and an optical mixer, the coupler being connected to the optical mixer by two optical fibers.
4. The light source frequency-shift calibration auxiliary channel structure of claim 3, wherein the photo-balance detector comprises a first photo-balance detector and a second photo-balance detector, each connected to the optical mixer and the operator, respectively.
5. The optical source frequency shift calibration auxiliary channel structure of claim 4, wherein the input terminal of the coupler is connected to the output terminal of the splitter, and one output terminal of the coupler is connected to the optical mixer, the first photoelectric balance detector and the operator in sequence; the other output end is connected with the optical mixer, the second photoelectric balance detector and the arithmetic unit in sequence.
6. The optical source frequency-shift calibration auxiliary channel structure as claimed in claim 5, wherein a delay fiber is connected in series to a single optical fiber between the coupler and the optical mixer.
7. The optical source frequency-shift calibration auxiliary channel structure of claim 6, wherein the optical mixer is a 90-degree optical mixer, and the coupler is used for inputting two orthogonal optical signals to the optical mixer.
8. The light source frequency shift calibration auxiliary channel structure according to claim 7, wherein the operator comprises a first averager, a second averager, a first multiplier, a second multiplier and an adder, one output end of the first photoelectric balance detector is connected with the first averager, the first multiplier and the adder in sequence, the other output end of the first photoelectric balance detector is connected with the first multiplier and the adder in sequence, one output end of the second photoelectric balance detector is connected with the second averager, the second multiplier and the adder in sequence, and the other output end of the second photoelectric balance detector is connected with the second multiplier and the adder in sequence.
9. An optical fiber vibration measuring device is characterized by comprising
Measuring device and light source frequency shift calibration auxiliary channel structure, splitter and splitter according to any of claims 1-8
The measuring device is connected.
10. The optical fiber vibration measuring device according to claim 9, wherein an output terminal of said operator is connected to
A data acquisition card of the measuring device.
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