CN210346898U - Sensing probe and optical fiber interference device for inhibiting polarization fading - Google Patents
Sensing probe and optical fiber interference device for inhibiting polarization fading Download PDFInfo
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Abstract
The utility model provides a sensing probe and restrain polarization and decline's optic fibre and interfere device. The sensing probe comprises a sealed cavity, wherein a sensing diaphragm, a first circulator and a first Faraday rotator mirror are arranged in the sealed cavity; the sensing diaphragm is used for sensing an external sound wave vibration signal; the sensing diaphragm is also provided with a boss to increase the sensitivity of the sensing probe; a sensing optical fiber ring is arranged on the sensing diaphragm, one end of the sensing optical fiber ring is connected with the input optical fiber, the other end of the sensing optical fiber ring is connected with a first port of the first circulator, and a second port of the first circulator is connected with the first Faraday rotator mirror; and the third port of the first circulator outputs detection light for sensing the change of the external sound wave vibration signal.
Description
Technical Field
The utility model belongs to the optical fiber interference device field especially relates to a sensing probe and restrain optical fiber interference device that polarization is declined.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
The optical fiber interference is widely applied to measurement of various external signals, such as vibration, temperature, stress and the like, and the principle of the optical fiber interference is that the phase change of interference light is caused according to the change of the external physical quantity, and the measurement of the external physical quantity is realized by detecting the phase change quantity of the interference light. Therefore, the acquisition of stable interference light becomes the key for realizing accurate measurement of external physical quantity.
The mach-zehnder optical fiber interference structure is widely applied to vibration signal measurement, but when the optical fiber is interfered by the outside world, the polarization state in the common single-mode optical fiber can be randomly changed due to the birefringence effect of the optical fiber, so that the random fading of the detection signal is caused, and especially when the polarization states of light in two arms of the optical fiber interferometer are orthogonal, the interference signal output by the interferometer is zero, so that the fading of the polarization-induced signal becomes a serious problem influencing the signal measurement of the interference type optical fiber sensor. The utility model discloses the people discover, at present, the researcher generally adopts to install polarization controller additional on single mode fiber and suppresses the polarization and fades, though has certain success, has increased system cost and has obvious hysteresis. The Zhouyong et al at university of Zhejiang performs theoretical analysis and simulation research on interference-type optical fiber sensor polarization-induced signal fading elimination by using a diversity detection technology, but three detectors are required to perform detection simultaneously, and the system is relatively troublesome. There are also polarization state modulation techniques, but this approach can significantly reduce the system signal-to-noise ratio.
SUMMERY OF THE UTILITY MODEL
In order to solve the above problem, the utility model provides a sensing probe and restrain polarization decline's optic fibre interference device.
The first aspect of the utility model provides a sensing probe, its interference that can avoid external environment for it is more accurate to visit the sound wave signal.
The second aspect of the utility model provides an optical fiber interference device that restraines polarization and decline, its mode that utilizes Faraday's rotating mirror and circulator to combine together restraines the polarization in the structure is interfered to optic fibre and is faded, can effectively restrain the polarization and decline, improves the SNR and the stability of system, realizes the accurate measurement to vibration signal.
The third aspect of the utility model provides an restrain optical fiber interference device's that polarization fades working method, its mode that utilizes Faraday's rotating mirror and circulator to combine together suppresses the polarization in the structure is interfered to the optic fibre and is faded, can effectively restrain the polarization and fade, improves the SNR and the stability of system, realizes the accurate measurement to vibration signal.
In order to achieve the above purpose, the utility model adopts the following technical scheme:
the utility model discloses a sensing probe of first aspect, include:
the sensing diaphragm, the first circulator and the first Faraday rotator mirror are arranged in the sealed cavity; the sensing diaphragm is used for sensing an external sound wave vibration signal; the sensing diaphragm is also provided with a boss to increase the sensitivity of the sensing probe; a sensing optical fiber ring is arranged on the sensing diaphragm, one end of the sensing optical fiber ring is connected with the input optical fiber, the other end of the sensing optical fiber ring is connected with a first port of the first circulator, and a second port of the first circulator is connected with the first Faraday rotator mirror; and the third port of the first circulator outputs detection light for sensing the change of the external sound wave vibration signal.
In one embodiment, the sensing diaphragm is a circular elastic diaphragm.
Above-mentioned technical scheme's advantage lies in, this embodiment adopts circular elastic diaphragm to detect the acoustic vibration signal, only detects the pressurized deformation volume at circular elastic diaphragm center like this, can take place deformation under faint acoustic signal to and make paste and receive the optic fibre ring on elastic diaphragm and produce the strain, improve the accuracy that the acoustic signal detected.
As an embodiment, the boss is a circular boss, and the circular boss coincides with the center of the circular elastic membrane.
The technical scheme has the advantages that the boss is circular and concentric with the elastic membrane, and the boss is used for increasing the sensitivity of the sensing membrane for detecting the acoustic signals.
In one embodiment, the sealed chamber is a metal cylinder.
The metal cylinder can avoid external environment's interference, and this embodiment all integrates sensing diaphragm, optical circulator and Faraday's rotating mirror in the metal cylinder, can accurately probe the sound wave signal.
In one embodiment, the sensing diaphragm and the boss are both made of organic polymer materials.
This can improve the accuracy of the detection of the acoustic signal.
The utility model discloses an optic fibre of suppression polarization fading of second aspect interferes device, include:
the optical signal output by the laser is equally divided into two beams of light by the first coupler, and the two beams of light respectively enter the sensing arm optical fiber and the reference arm optical fiber; the sensing arm optical fiber is connected with the sensing probe, wherein the sensing arm optical fiber is an input optical fiber; the reference arm optical fiber is connected with a first port of a second optical circulator, and a second port of the second optical circulator is connected with a second Faraday rotator mirror; a third port of the second optical circulator outputs reference light;
and the third port of the first optical circulator and the third port of the second circulator are both connected with a second coupler, the probe light and the reference light form interference in the second coupler and output two paths of interference light, and the two paths of interference light are subjected to difference and demodulated by a demodulator to output phase change caused by vibration so as to obtain sound wave vibration information.
In one embodiment, two output paths of interference light output by the second coupler are transmitted to the demodulator through the first photodetector and the second photodetector, respectively.
In one embodiment, the sensing arm fiber and the reference arm fiber are single mode fibers.
The utility model has the advantages that:
(1) the sensing probe of the utility model integrates the sensing diaphragm, the first circulator and the first Faraday rotator mirror in the sealed cavity, thereby avoiding external interference and improving the accuracy of detection;
(2) the circulator of the utility model can effectively avoid the light reflected by the Faraday rotator from influencing the light source, so that the detected interference signal is more stable, and the change of the external signal is more accurately measured;
(3) the utility model discloses an optical fiber interference device structure that suppression polarization was declined is mach-zehnder interference structure, the utility model discloses be applied to mach-zehnder interference structure with Faraday's rotating mirror and circulator in, because Faraday's rotating mirror can make the polarization state of reflected light wave only relevant with the polarization state of incident light wave, and do not receive the influence of middle transmission optic fibre birefringence effect, the light that makes two arms return has the same polarization state all the time, therefore birefringence effect and the polarization that can effectively restrain single mode fiber are undulant, can effectively restrain the polarization and decline, the SNR and the stability of system have been improved, realized the accurate measurement to vibration signal.
Drawings
The accompanying drawings, which form a part of the specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention without unduly limiting the scope of the invention.
Fig. 1 is a schematic structural diagram of a sensing probe according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of an optical fiber interference device for suppressing polarization fading according to an embodiment of the present invention;
figure 3 is a schematic diagram of the faraday rotator mirror according to an embodiment of the present invention;
fig. 4 is a schematic diagram of the operation of a first coupler according to an embodiment of the present invention;
fig. 5 is a schematic diagram of the detection of the first detector output by the second coupler according to the embodiment of the present invention;
fig. 6 is a schematic diagram of the detection of the second detector output by the second coupler according to the embodiment of the present invention.
Detailed Description
The present invention will be further explained with reference to the accompanying drawings and examples.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the invention. 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 invention 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 in accordance with the invention. As used herein, the singular forms "a", "an" and "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, unless the context clearly indicates otherwise.
In the present invention, the terms such as "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "side", "bottom", and the like indicate the position or positional relationship based on the position or positional relationship shown in the drawings, and are only the terms determined for convenience of describing the structural relationship of each component or element of the present invention, and are not specific to any component or element of the present invention, and are not to be construed as limiting the present invention.
In the present invention, terms such as "fixedly connected", "connected", and the like are to be understood in a broad sense, and may be fixedly connected, or may be integrally connected or detachably connected; may be directly connected or indirectly connected through an intermediate. The meaning of the above terms in the present invention can be determined according to specific situations by persons skilled in the art, and should not be construed as limiting the present invention.
Example 1
As shown in fig. 1, the present embodiment provides a sensing probe, which includes:
the device comprises a sealed cavity 12, wherein a sensing diaphragm 3, a first circulator 6 and a first Faraday rotator mirror 7 are arranged in the sealed cavity 12; the sensing diaphragm 3 is used for sensing an external sound wave vibration signal; the sensing diaphragm 3 is also provided with a boss 13 to increase the sensitivity of the sensing probe; a sensing optical fiber ring 18 is arranged on the sensing diaphragm 3, one end of the sensing optical fiber ring 18 is connected with an input optical fiber, the other end of the sensing optical fiber ring 18 is connected with a first port d of the first circulator 6, and a second port e of the first circulator 6 is connected with the first Faraday rotator mirror 7; the third port f of the first circulator 6 outputs the detection light for sensing the change of the external acoustic vibration signal.
In one embodiment, the sensing diaphragm is a circular elastic diaphragm.
For example: the Young's modulus of the circular elastic membrane is 10GPa, the Poisson ratio is 0.3, the radius is 50mm, and the thickness is 1 mm.
Above-mentioned technical scheme's advantage lies in, this embodiment adopts circular elastic diaphragm to detect the acoustic vibration signal, only detects the pressurized deformation volume at circular elastic diaphragm center like this, can take place deformation under faint acoustic signal to and make paste and receive the optic fibre ring on elastic diaphragm and produce the strain, improve the accuracy that the acoustic signal detected.
As an embodiment, the boss is a circular boss, and the circular boss coincides with the center of the circular elastic membrane.
In this embodiment, the sensing diaphragm and the boss are made of the same material and made of an organic polymer material. This can improve the accuracy of the detection of the acoustic signal.
The boss 13 can correspondingly increase the sensitivity of the sensing probe, and both the boss and the diaphragm are made of organic polymer materials, such as: the radius of the boss is 5mm, and the thickness is 0.3 mm.
The technical scheme has the advantages that the boss is circular and concentric with the elastic membrane, and the boss is used for increasing the sensitivity of the sensing membrane for detecting the acoustic signals.
The sensing probe adopts the elastic membrane with the circular boss, can deform under weak acoustic signals and further influences the strain of the optical fiber ring pasted on the elastic membrane. The acoustic wave of the external action is assumed to be:
wherein p isaAmplitude of the acoustic wave, ω1The circular frequency of the sound wave.
Setting the thickness of the elastic membrane as H and the radius as R, setting the boss and the membrane as the same material, setting the thickness of the boss as H and the radius as RaThe amount of deformation η in the center of the circular elastic diaphragm when r is 0 is often of interest only for such acoustic wave sensors.
Wherein χ is:
wherein α raand/R, β is H/(H + H), mu is the Poisson ratio of the membrane material, and E is the Young modulus of the sensing membrane.
The deformation of the circular elastic membrane causes the change of the length of the optical fiber by delta L:
where L is the length of the entire sensing fiber, dfTo sense the diameter of the optical fiber, r1The inner radius of the sensing fiber ring.
In one embodiment, the sealed chamber is a metal cylinder. As shown in fig. 1, the metal cylinder is an aluminum cylinder 14.
The sensing diaphragm is fixed on a metal cylinder (such as an aluminum cylinder) in a peripheral fixing mode, and a certain prestress is applied to the periphery of the diaphragm. When sound waves of the loudspeaker act on the circular film, the film deforms along with the change of sound pressure, so that the stress distribution of the sensing optical fiber ring 18 stuck on the film is changed, and the length and the effective refractive index of the sensing optical fiber ring are changed.
The metal cylinder can avoid external environment's interference, and this embodiment all integrates sensing diaphragm, optical circulator and Faraday's rotating mirror in the metal cylinder, can accurately probe the sound wave signal.
Example 2
As shown in fig. 2, the optical fiber interference device for suppressing polarization fading of the present embodiment includes:
the optical signal output by the laser 1 is equally divided into two beams of light by the first coupler 2, and the two beams of light respectively enter the sensing arm optical fiber and the reference arm optical fiber; the sensing arm optical fiber is connected with the sensing probe shown in fig. 1, wherein the sensing arm optical fiber is an input optical fiber; the reference arm optical fiber is connected with a first port a of the second optical circulator 4, and a second port b of the second optical circulator 4 is connected with the second Faraday rotator mirror; the third port c of the second optical circulator 4 outputs the reference light;
the third port f of the first optical circulator 6 and the third port c of the second circulator 4 are both connected with the second coupler 8, the probe light and the reference light form interference in the second coupler 8 and output two paths of interference light, and the two paths of interference light are subjected to difference and demodulated by the demodulator 11 to output phase change caused by vibration, so that sound wave vibration information is obtained.
Two paths of interference light output by the second coupler 8 are respectively transmitted to the demodulator 11 through the first photodetector 10 and the second photodetector 9.
In this embodiment, the laser is a distributed feedback laser having a wavelength of 1550 nm.
It is understood that in other embodiments, the model of the laser and its emission wavelength may be specifically selected by those skilled in the art based on the actual circumstances.
The sensing fiber ring 18 enters the interior of the sensing probe through the fiber entrance hole 16. The sensing arm optical fiber is pasted on the sensing diaphragm 3 with the boss 13 in a ring shape, the sensing diaphragm 3 is fixed on the aluminum cylinder 14 in a peripheral fixed support mode, the tail end of the sensing optical fiber ring is connected with the d port of the first circulator 6, the e port of the first circulator 6 is connected with the first Faraday rotator mirror 7, the first circulator 6 and the first Faraday rotator mirror 7 are both fixed on the bottom end face of the aluminum cylinder 14 by adopting an elastic pressing sheet 15, and the f port of the first circulator 6 is connected with an optical fiber and is externally connected into the second coupler 8 through an optical fiber outlet 17 on the aluminum cylinder. The output end of the second coupler 8 is respectively connected with a second photoelectric detector 9 and a first photoelectric detector 10, the structure forms Mach-Zehnder interference, and the second photoelectric detector 9 and the first photoelectric detector 10 are connected to a demodulator 11.
A mach-zehnder optical fiber interference process for suppressing polarization state attenuation according to the present embodiment is described as follows:
the light wave is emitted by the laser, and the light field of the incident light can be expressed as:
in the formula E0Amplitude of light wave, ω frequency of light wave, k0The wave number of the light wave when propagating in vacuum, n is the refractive index of the fiber core of the quartz single-mode fiber, x is the optical path passed in the process of propagating the light wave, and the light intensity of the light wave is obtained as follows:
I0＝EE*＝E0 2
the sensing arm optical fiber and the reference arm optical fiber are both single-mode optical fibers.
After the light wave is incident to the first coupler, the light wave is divided into two paths of light and transmitted to two single-mode optical fibers, wherein one single-mode optical fiber serves as a sensing arm, and the other single-mode optical fiber serves as a reference arm. Due to the cross coupling, the transmitted light in the sensing arm is delayed by pi/2 phase, as shown in FIG. 4.
The light field of the incident light wave after passing through the first coupler and the reference arm light is as follows:
where the interferometer arms have the same optical attenuation coefficient α, zeta being the coupling coefficient of the first coupler, lrIs the optical path in the fiber through the reference arm.
Due to the phase delay, the optical field of the incident light wave after passing through the first coupler and the sensing arm is as follows:
in the formula IsIs the optical path in the sensing arm fiber.
The sensing probe adopts the elastic membrane with the circular boss, can deform under weak acoustic signals and further influences the strain of the optical fiber ring pasted on the elastic membrane. The acoustic wave of the external action is assumed to be:
wherein p isaAmplitude of the acoustic wave, ω1The circular frequency of the sound wave.
Setting the thickness of the elastic membrane as H and the radius as R, setting the boss and the membrane as the same material, setting the thickness of the boss as H and the radius as RaThe amount of deformation η in the center of the circular elastic diaphragm when r is 0 is often of interest only for such acoustic wave sensors.
Wherein χ is:
wherein α raand/R, β is H/(H + H), mu is the Poisson ratio of the membrane material, and E is the Young modulus of the sensing membrane.
The deformation of the circular elastic membrane causes the change of the length of the optical fiber by delta L:
where L is the length of the entire sensing fiber, dfTo sense the diameter of the optical fiber, r1The inner radius of the sensing fiber ring.
Due to sensing lightThe variation of the length of the fiber causes the phase of the interference light to vary
Where n is the refractive index of the core of the transmission fiber and λ is the wavelength of the incident light. Therefore, the phase change of the interference light caused by the external sound wave signal can be obtained.
Due to the birefringence effect of the optical fiber, the polarization state of light is slowly and randomly changed when the light propagates in the optical fiber, and the visibility of an output interference signal is reduced, so that the signal is faded. The Faraday rotator mirror can realize orthogonal transformation of the polarization state of input light, and can effectively avoid random change of the polarization state of the optical fiber.
The sensing arm transmits light to enter a port e from a port d of the first optical circulator 6, the reference arm transmits light to enter a port b from a port a of the second optical circulator, the light is reflected by the first Faraday rotator and the second Faraday rotator respectively and then is emitted from ports f and c of the first optical circulator and the second optical circulator, and therefore the influence of the reflected light on a light source is effectively avoided. When the angle of rotation of the faraday rotator mirror is 45 °, the process by which light is reflected out of the second and first optical circulator ports c, f, regardless of losses, can be represented by a Jones matrix as:
as shown in fig. 3, assuming that the polarization direction of the incident light wave is vertical, when the magnetic field generated by the outer magnetic ring of the faraday material 19 is appropriate, the polarization direction of the light wave can be deflected by 45 °, and after being reflected by the high-reflection mirror 20, the reflected light passes through the faraday material 19 again, so that the polarization direction of the reflected light wave is deflected by 45 ° again on the basis of the previous deflection direction to become horizontal, and the incident light wave is deflected by 90 ° under the action of the faraday rotator, that is, the polarization state of the output light is orthogonal to the polarization state of the input light and independent of the transmission matrix of the transmission optical fiber, and the influence of birefringence in the transmission optical fiber can be eliminated through the circulator and the faraday rotator, so that the lights emitted from the two arms can completely interfere in the second coupler, and the polarization fading of the sensing light and the reference light can be effectively suppressed.
A single mode fiber can be considered as a cascade of a phase retarder and an optical rotator, and the single mode fiber Jones matrix of one arm of the mach-zehnder interferometer is:
wherein:
a＝cos(δm/2)+i cos 2θmsin(δm/2)
b＝i sin 2θmsin(δm/2)
wherein the values of the parameters a, b are related to the birefringence of the length of optical fiber, i.e. the conjugate, θmRepresenting the angle, δ, between the fast axis of the equivalent phase retarder and the x-axis of the reference coordinatemThe equivalent phase difference between the fast and slow axes in the single mode fiber is shown. After light exits from the second optical circulator port c and the first optical circulator port f, the reverse transmission Jones matrix of the rear-section optical fiber is as follows:
when a beam of linearly polarized light Ei＝[EixEiy]TThe equivalent transmission optical fiber reaches the Faraday rotator mirror and is reflected to the rear equivalent transmission optical fiber, the equivalent Jones matrixes of the respective elements are multiplied in sequence, and output light E can be obtained0：
Namely, the existence of: ei·Eo T＝[EixEiy]T·[-EiyEix]＝0
It can be seen that the polarization state of the output light is orthogonal to the polarization state of the input light and independent of the transmission matrix of the transmission fiber. Namely, after a linearly polarized light is transmitted in the forward direction through a section of optical fiber, due to the action of the Faraday rotator, the polarization direction of the light wave rotates by 45 degrees clockwise or anticlockwise, and when the light reflected back from the reflector passes through the Faraday rotator in the reverse direction, the polarization state of the light wave rotates by 45 degrees again in the same direction, the reverse transmission matrix and the forward transmission matrix of the light in the optical fiber are transposed, compared with the incident light, the light reflected back in the whole transmission process rotates by 90 degrees in the polarization state, namely, the light is only related to the polarization state of the incident light and is not influenced by the transmission optical fiber, the influence of double refraction in the transmission optical fiber can be eliminated, and the slow random change of light polarization is effectively overcome. The light emitted from the two arms will interfere completely in the second coupler, effectively suppressing the polarization fading in the mach-zehnder interferometer.
The light waves emitted by the two arms form interference in the second coupler, and the reference light and the detection light generate phase delay, so that the two conditions can be divided into two conditions:
the interference light is incident on the first photodetector, as shown in fig. 5:
for the reference light, a first time phase delay is generated in the second coupler, and the optical field is as follows:
for the probe light, no phase delay is generated in the second coupler, and due to secondary coupling, the optical field is:
light emitted from the reference arm and the sensing arm interferes in the second coupler, and the intensity I of the interference light detected by the first photodetector1Comprises the following steps:
wherein
The phase difference caused by the external vibration signal.
2: the interference light is incident on the second photodetector, as shown in fig. 6:
since the reference light does not generate phase delay in the second coupler, its optical field is:
for the probe light, a second phase delay is generated in the second coupler, and the optical field is:
light emitted from the reference arm and the sensing arm interferes in the second coupler, and the intensity I of the interference light detected by the second photodetector2Comprises the following steps:
I2＝(Er2+Es2)(Er2+Es2)*
from the conclusion of the two-beam interference:
wherein I0Is the intensity of the light radiated by the laser,
for the phase shift caused by the external vibration signal,
is the initial phase difference of the two arms of the interferometer.
When the coupling coefficient ζ of the two couplers is 0.5, the light intensity signals detected by the two photodetectors are respectively:
the difference between the two detected light intensity signals can be obtained:
the demodulator demodulates the light intensity to obtain the phase change, and then the vibration signal is measured.
The Faraday rotator mirror is added in the Mach-Zehnder optical fiber interference structure, so that the polarization state of transmitted light is not influenced by the birefringence effect of the optical fiber, the visibility of the optical fiber interference fringes is stable to be 1, the intensity of interference signals is stable, the polarization fading phenomenon is inhibited, the quality of detected signals is improved, meanwhile, the optical fiber of the system is not influenced by external environment noise, the signal-to-noise ratio of the system can be effectively improved, the polarization stability of the system is enhanced, and a stable optical path state is provided for the Mach-Zehnder optical fiber interference structure.
The Faraday rotator enables the polarization directions of two beams of light interfering with each other to be consistent, the obtained interference effect is optimal, the light interference power spectrum intensity is improved, the error of data obtained by demodulating interference signals can be reduced, the precision of the whole sound wave sensing system is improved, the measurement range of the measurement optical path difference of the system can be enlarged to a certain extent, and the dynamic range of the system is improved.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. A sensing probe, comprising:
the sensing diaphragm, the first circulator and the first Faraday rotator mirror are arranged in the sealed cavity; the sensing diaphragm is used for sensing an external sound wave vibration signal; the sensing diaphragm is also provided with a boss to increase the sensitivity of the sensing probe; a sensing optical fiber ring is arranged on the sensing diaphragm, one end of the sensing optical fiber ring is connected with the input optical fiber, the other end of the sensing optical fiber ring is connected with a first port of the first circulator, and a second port of the first circulator is connected with the first Faraday rotator mirror; and the third port of the first circulator outputs detection light for sensing the change of the external sound wave vibration signal.
2. A sensing probe according to claim 1, wherein the sensing diaphragm is a circular elastomeric diaphragm.
3. A sensing probe according to claim 2 wherein the boss is a circular boss which coincides with the centre of the circular diaphragm.
4. A sensing probe according to claim 1 wherein the sealed chamber is a metal cylinder.
5. A sensing probe according to claim 1, wherein the sensing diaphragm and the boss are made of an organic polymer material.
6. An optical fiber interference device for suppressing polarization fading, comprising:
the optical signal output by the laser is equally divided into two beams of light by the first coupler, and the two beams of light respectively enter the sensing arm optical fiber and the reference arm optical fiber; the sensing arm optical fiber is connected with the sensing probe of any one of claims 1-5, wherein the sensing arm optical fiber is an input optical fiber; the reference arm optical fiber is connected with a first port of a second optical circulator, and a second port of the second optical circulator is connected with a second Faraday rotator mirror; a third port of the second optical circulator outputs reference light;
and the third port of the first optical circulator and the third port of the second circulator are both connected with a second coupler, the probe light and the reference light form interference in the second coupler and output two paths of interference light, and the two paths of interference light are subjected to difference and demodulated by a demodulator to output phase change caused by vibration so as to obtain sound wave vibration information.
7. The optical fiber interference device for suppressing polarization fading of claim 6, wherein the two output interference lights outputted from the second coupler are transmitted to the demodulator through the first photodetector and the second photodetector, respectively.
8. The optical fiber interference device for suppressing polarization fading of claim 6 wherein the sensing arm fiber and the reference arm fiber are single mode fibers.
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| CN110631684B (en) * | 2019-10-23 | 2024-02-13 | 吉林大学 | Sensing probe, optical fiber interference device and method for inhibiting polarization fading |
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