Optical fiber polarization characteristic detection method and device based on sound waves

Abstract

The invention discloses an optical fiber polarization characteristic detection method and device based on sound waves, and the method comprises the steps: enabling a laser device to emit a laser beam to enter an optical fiber coupler through an aperture diaphragm, a polarizer and a semi-reflecting and semi-transmitting mirror in sequence, and enabling the optical fiber coupler to divide the laser beam into a first light beam and a second light beam; the first light beam enters the first Faraday rotating mirror through the first optical fiber; the second light beam enters a second Faraday rotating mirror through a second optical fiber; the first optical fiber is a bare optical fiber, and the second optical fiber is tightly wound on the part body; reflected light of the first Faraday rotating mirror and the second Faraday rotating mirror returns along an original light path and is coupled by the optical fiber coupler to reach the semi-reflecting and semi-transmitting mirror; the sound signal is played to the second optical fiber tightly wound on the part body, and the first optical fiber is subjected to silencing treatment at the same time; and the semi-reflecting and semi-transmitting mirror reflects the returned coupled reflected light to the polarization analyzer to obtain polarization information. The method is used for detecting the influence of the sound wave frequency on the polarization characteristic of the optical fiber, and the accuracy of optical path transmission is ensured.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber sensing technology, and in particular to an optical fiber polarization characteristic detection method and device based on acoustic waves. Background Art

[0002] Fiber optic optical path uses fiber optic sensing technology, which has high sensitivity, strong anti-electromagnetic interference ability, and is easy to reuse on a large scale. In recent years, fiber optic sensing has been widely promoted in engineering applications, and has been used in ocean detection, towed detection arrays, and submarine side detection arrays, all of which have achieved good application results.

[0003] Light sources, transmission losses, equipment noise, and photoelectric conversion circuits can all become interference sources, resulting in large errors in the results; in addition, since most of them are micro-bend structures, the light intensity of optical fiber transmission will be lost, which will also cause large deviations in the results, making it difficult to recover for long-distance sensing. Fiber-optic interferometric acoustic wave sensors are more sensitive, but they are also quite sensitive to other variables, such as temperature.

[0004] The fiber polarization optical path avoids the above problems and has the advantages of simple optical path, high sensitivity and simple devices. The core of this technology is the ability to convert acoustic signals into detectable changes in polarization information. In this way, information can be obtained from a wide frequency range from low frequency to high frequency to form changes in polarization images. In order to achieve full-band information acquisition, the polarization optical path needs to be able to generate acoustic signals covering from low frequency to high frequency. Such a requirement means that the signal generator must have the ability to generate acoustic signals in a wide frequency range to ensure the integrity and reliability of the data.

[0005] Although fiber optic polarization sensing technology has many advantages, it also faces a series of challenges:

[0006] During the detection process, the optical fiber polarization light path also needs to perform a series of operations such as signal amplification, filtering, and noise reduction on the entire system, which undoubtedly increases the complexity and cost of implementation. In addition, delays and losses may occur in multi-point distributed sensing and long-distance transmission.

[0007] Therefore, how to provide a method and device for detecting the polarization characteristics of an optical fiber based on acoustic waves is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0008] In view of the above research status and existing problems, the present invention provides a method and device for detecting optical fiber polarization characteristics based on acoustic waves, which is used to detect the influence of acoustic wave frequency on optical fiber polarization characteristics, and helps to ensure the accuracy of optical path transmission.

[0009] The present invention provides a method for detecting optical fiber polarization characteristics based on acoustic waves, comprising the following steps:

[0010] The laser beam emitted by the laser sequentially passes through the aperture diaphragm and the polarizer to reach the half-reflecting half-mirror. The laser beam passes through the half-reflecting half-mirror and enters the fiber coupler. The fiber coupler divides the laser beam into a first beam and a second beam. The first beam is incident on the first Faraday rotator through the first optical fiber. The second beam is incident on the second Faraday rotator through the second optical fiber. The first optical fiber is a bare optical fiber, and the second optical fiber is tightly wound on the part body.

[0011] The reflected light of the first Faraday rotator and the second Faraday rotator returns along the original optical path respectively, and reaches the half-reflecting half-mirror through the optical fiber coupler;

[0012] Playing a sound signal to a second optical fiber tightly wound around the component body, and simultaneously performing a noise reduction treatment on the first optical fiber;

[0013] The semi-reflective and semi-mirror mirror reflects the returned coupled reflected light to the polarizer to obtain polarization information.

[0014] Preferably, the wavelength of the laser beam emitted by the laser is 632.8 nm.

[0015] Preferably, the speaker plays sound signals of different frequencies, and the frequency range of the sound signals includes high frequency and low frequency.

[0016] Preferably, the method further comprises obtaining a polarization state image through a camera using the polarization information for display.

[0017] Preferably, polarization state images under different light input amounts are obtained by adjusting the angle of the polarizer in the polarizer.

[0018] The present invention also provides an optical fiber polarization characteristic detection device based on acoustic waves, comprising a laser, an aperture diaphragm, a polarizer, a half-reflecting half-mirror and an optical fiber coupler which are sequentially arranged along the optical path direction; the laser beam emitted by the laser sequentially passes through the aperture diaphragm and the polarizer to reach the half-reflecting half-mirror, the laser beam passes through the half-reflecting half-mirror and enters the optical fiber coupler, and the optical fiber coupler divides the laser beam into a first beam and a second beam; the first beam is incident on a first Faraday rotator through a first optical fiber; the second beam is incident on a second Faraday rotator through a second optical fiber; the first optical fiber is a bare optical fiber, and the second optical fiber is tightly wound on the part body;

[0019] The reflected light of the first Faraday rotator and the second Faraday rotator returns along the original optical path respectively, and is coupled to the half-reflecting half-mirror through the optical fiber coupler; the half-reflecting half-mirror reflects the returned coupled reflected light to the analyzer;

[0020] A speaker is placed within a specified distance range from the part body to play a sound signal to a second optical fiber tightly wound around the part body; a silencer is set within a specified distance range from the first optical fiber to silence the first optical fiber.

[0021] Preferably, the laser is used to emit a laser beam with a wavelength of 632.8 nm.

[0022] Preferably, the speaker is used to play sound signals of different frequencies, and the frequency range of the sound signal includes high frequency and low frequency.

[0023] Preferably, it also includes a camera and a computer; the polarizer is connected to the camera and the computer in sequence; the camera is used to receive the polarization information sent by the polarizer and generate a polarization state image, and the computer is used to display the polarization state image.

[0024] Preferably, the component body is fixed on a bottom plate, and the optical fiber is tightly wound around the component body in one direction.

[0025] Compared with the prior art, it has the following beneficial effects:

[0026] The present invention discovered the problem of partially complex optical paths in the polarization process, and solved the problem of large result errors caused by factors such as light sources, transmission losses, equipment noise, and photoelectric conversion circuits in the prior art by optimizing the polarization characteristics of optical fibers. The accuracy of optical path transmission is ensured through a reasonably designed optical path layout.

[0027] The present invention can not only effectively detect the influence of sound waves on the polarization characteristics of optical fibers, but also obtain image changes of polarization characteristics, and intuitively display these influences through images, providing important data support for subsequent research and applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on the provided drawings without creative work.

[0029] Figure 1 An optical path diagram of a method for detecting polarization characteristics of optical fiber based on acoustic waves provided in an embodiment of the present invention;

[0030] Figure 2 A schematic structural diagram of a second optical fiber winding component body provided by an embodiment of the present invention;

[0031] Figure 3A polarization state diagram when the angle of the polarizer provided in the embodiment of the present invention is 0° and the sound wave frequency is 528 Hz;

[0032] Figure 4 A polarization state diagram when the angle of the polarizer provided in the embodiment of the present invention is 0° and the sound wave frequency is 1000 Hz;

[0033] Figure 5 A polarization state diagram when the angle of the polarizer provided in the embodiment of the present invention is 45° and the sound wave frequency is 528 Hz;

[0034] Figure 6 The polarization state diagram when the angle of the polarizer provided in the embodiment of the present invention is 45° and the sound wave frequency is 1000 Hz. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] like Figure 1 As shown, the first aspect of the embodiment of the present invention discloses a method for detecting polarization characteristics of optical fiber based on acoustic waves, comprising the following steps:

[0037] The laser beam emitted by the laser 1 passes through the aperture diaphragm 2 and the polarizer 3 to the half-reflecting half-mirror 4 in sequence, and the laser beam enters the fiber coupler 5 through the half-reflecting half-mirror 4. The fiber coupler 5 divides the laser beam into a first beam and a second beam; the first beam is incident on the first Faraday rotator 71 through the first optical fiber 61; the second beam is incident on the second Faraday rotator 72 through the second optical fiber 62; the first optical fiber 61 is a bare optical fiber, and the second optical fiber 62 is tightly wound on the part body; the reflected light of the first Faraday rotator 71 and the second Faraday rotator 72 returns along the original optical path respectively, and is coupled to the half-reflecting half-mirror 4 through the fiber coupler 5; a sound signal is played to the second optical fiber 62 tightly wound on the part body, and the first optical fiber 61 is simultaneously silenced; the half-reflecting half-mirror 4 reflects the returned coupled reflected light to the analyzer 8 to obtain polarization information.

[0038] In this embodiment, the laser beam passes through the polarizer 3 and the half-reflecting mirror 4, and the light signal acts on the first optical fiber 61 and the second optical fiber 62. The half-reflecting mirror 4 reflects the sound-processed light signal, and the reflected light signal passes through the half-reflecting mirror 4 to the analyzer 8, and finally displayed on the computer 10 through the camera 9. Thus, the accuracy of the optical path modulation part is increased.

[0039] It should be noted that the first optical fiber 61 is a bare optical fiber, which means that it is not wound around any component body. The first optical fiber 61 serves as a control group optical fiber of the second optical fiber 62 .

[0040] In one embodiment, the laser 1 is a He-Ne laser 1, and the wavelength of the laser beam emitted by the laser 1 is 632.8 nm.

[0041] In one embodiment, the aperture stop 2 is used to converge the laser beam and prevent the beam from diverging.

[0042] In one embodiment, the speaker plays sound signals of different frequencies, and the frequency range of the sound signal includes high frequency and low frequency.

[0043] In one embodiment, the second optical fiber 62 is wound starting from one end of the part body, uniformly wound along a single direction to the surface of the part body, and ends winding from the other end of the part body. The part body may be a cylinder.

[0044] In one embodiment, the method for performing noise reduction treatment on the first optical fiber 61 includes: placing the first optical fiber 61 in a soundproof box, filling it with sponge, and sealing the top layer with a thick rubber cover. Specifically, the first optical fiber 61 can use an optical fiber hydrophone, and another sensor probe of the optical fiber hydrophone is placed in the soundproof box.

[0045] In one embodiment, the method further includes obtaining a polarization state image by using the camera 9 to display the polarization information.

[0046] In one embodiment, polarization state images under different light input amounts are obtained by adjusting the angle of the polarizer in the polarizer 3 (eg, 0°, 45°).

[0047] The second aspect of the embodiment of the present invention further provides an optical fiber polarization characteristic detection device based on acoustic waves, which is used to perform all the steps of the first aspect of the embodiment. It includes:

[0048] A laser 1, an aperture diaphragm 2, a polarizer 3, a half-reflecting half-mirror 4 and a fiber coupler 5 are sequentially arranged along the optical path; the laser beam emitted by the laser 1 sequentially passes through the aperture diaphragm 2 and the polarizer 3 to reach the half-reflecting half-mirror 4, the laser beam passes through the half-reflecting half-mirror 4 and enters the fiber coupler 5, and the fiber coupler 5 divides the laser beam into a first beam and a second beam; the first beam is incident on the first Faraday rotator 71 through the first optical fiber 61; the second beam is incident on the second Faraday rotator 72 through the second optical fiber 62; the first optical fiber 61 is a bare The optical fiber, the second optical fiber 62 is tightly wound on the part body; the reflected light of the first Faraday rotator 71 and the second Faraday rotator 72 returns along the original optical path respectively, and is coupled to the half-reflecting half-mirror 4 through the optical fiber coupler 5; the half-reflecting half-mirror 4 reflects the returned coupled reflected light to the polarizer 8; a speaker is placed within a specified distance range from the part body to play a sound signal to the second optical fiber 62 tightly wound on the part body; a silencing device is set within a specified distance range from the first optical fiber 61 to perform silencing treatment on the first optical fiber 61.

[0049] In one embodiment, the laser 1 is a He-Ne laser, and the laser 1 is used to emit a laser beam with a wavelength of 632.8 nm.

[0050] In one embodiment, the aperture stop 2 is used to converge the laser beam and prevent the beam from diverging.

[0051] In one embodiment, the polarizer 3 is composed of a polarizing plate, and polarization state images under different light input amounts are obtained by adjusting the angle of the polarizing plate (eg, 0°, 45°).

[0052] In one embodiment, the surface of the semi-reflective half-mirror 4 facing the polarizer 3 is coated with a high-transmittance film for transmitting the laser beam through the polarizer 3, and the surface of the semi-reflective half-mirror 4 facing the fiber coupler 5 is coated with a high-reflection film for reflecting the light beam returned by the fiber coupler 5 to the analyzer 8.

[0053] In one embodiment, the speaker is used to play sound signals of different frequencies, and the frequency range of the sound signal includes high frequency and low frequency. The sound wave frequencies selected in this embodiment are 500 Hz and 10000 Hz respectively.

[0054] In one embodiment, it also includes a camera 9 and a computer 10; the polarizer 8 is connected to the camera 9 and the computer 10 in sequence; the camera 9 is used to receive the polarization information sent by the polarizer 8 and generate a polarization state image, and the computer 10 is used to display the polarization state image.

[0055] In one embodiment, the component body is fixed on the bottom plate, and the optical fiber is tightly wound around the component body in one direction. Figure 2 As shown, the upper end of the part body is the winding input end of the second optical fiber 62, and the lower end is the winding tail end of the second optical fiber 62. The part body can be a cylinder.

[0056] like Figure 3 The figure shows the polarization state images when the angle of the polarizer is 0° and the sound wave frequency is 528 Hz, where (a) is the polarization image without the action of sound waves, and (b) is the polarization image under the action of 528 Hz sound waves. It can be seen that the spot density of the polarization image is slightly reduced.

[0057] like Figure 4 The figure shows the polarization state images when the angle of the polarizer is 0° and the sound wave frequency is 1000 Hz, where (a) is the polarization image without the action of sound waves, and (b) is the polarization image under the action of 1000 Hz sound waves. It can be seen that the image shape becomes larger and the spot density decreases.

[0058] like Figure 5 The figure shows the polarization state images when the angle of the polarizer is 45° and the sound wave frequency is 528 Hz, where (a) is the polarization image without the action of sound waves, and (b) is the polarization image under the action of 528 Hz sound waves. It can be seen that the spot density is slightly reduced and the image shape is slightly changed.

[0059] like Figure 6 The figure shows the polarization state images when the angle of the polarizer is 45° and the sound wave frequency is 1000 Hz, where (a) is the polarization image without the action of sound waves, and (b) is the polarization image under the action of 1000 Hz sound waves. It can be seen that the light spot becomes significantly brighter and the shape changes significantly.

[0060] From the polarization state image, it can be seen that the sound wave not only affects the polarization of the laser beam, but also may affect the convergence characteristics of the laser beam. By observing the image, it is found that the difference between the image without sound wave incident and the image with sound wave incident is visible to the naked eye, and the image vibration of the 10000hz sound wave when the sound wave is incident is more obvious than the dynamic image of the 500hz sound wave.

[0061] The above is a detailed introduction to the method and device for detecting the polarization characteristics of optical fibers based on acoustic waves provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present invention.

[0062] In this article, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

Claims

1. A method for detecting polarization characteristics of optical fiber based on acoustic waves, characterized in that: The steps include: The laser beam emitted by the laser sequentially passes through the aperture diaphragm and the polarizer to reach the half-reflecting half-mirror. The laser beam passes through the half-reflecting half-mirror and enters the fiber coupler. The fiber coupler divides the laser beam into a first beam and a second beam. The first beam is incident on the first Faraday rotator through the first optical fiber. The second beam is incident on the second Faraday rotator through the second optical fiber. The first optical fiber is a bare optical fiber, and the second optical fiber is tightly wound on the part body. The reflected light of the first Faraday rotator and the second Faraday rotator returns along the original optical path respectively, and is coupled to the half-reflecting half-mirror through the optical fiber coupler; Playing a sound signal to a second optical fiber tightly wound around the component body, and simultaneously performing a noise reduction treatment on the first optical fiber; The semi-reflective and semi-mirror mirror reflects the returned coupled reflected light to the polarizer to obtain polarization information.

2. The method for detecting optical fiber polarization characteristics based on acoustic waves according to claim 1, characterized in that: The wavelength of the laser beam emitted by the laser is 632.8 nm.

3. The method for detecting optical fiber polarization characteristics based on acoustic waves according to claim 1, characterized in that: The speaker plays sound signals of different frequencies, and the frequency range of the sound signals includes high frequency and low frequency.

4. The method for detecting optical fiber polarization characteristics based on acoustic waves according to claim 1, characterized in that: The method also includes obtaining a polarization state image by a camera using the polarization information for display.

5. The method for detecting optical fiber polarization characteristics based on acoustic waves according to claim 1, characterized in that: By adjusting the angle of the polarizer in the polarizer, polarization state images under different light input amounts can be obtained.

6. An optical fiber polarization characteristic detection device based on acoustic waves, characterized in that: The invention comprises a laser, an aperture diaphragm, a polarizer, a half-reflecting half-mirror and an optical fiber coupler which are sequentially arranged along the optical path direction; the laser beam emitted by the laser sequentially passes through the aperture diaphragm and the polarizer to reach the half-reflecting half-mirror, the laser beam passes through the half-reflecting half-mirror and enters the optical fiber coupler, and the optical fiber coupler divides the laser beam into a first beam and a second beam; the first beam is incident on a first Faraday rotator through a first optical fiber; the second beam is incident on a second Faraday rotator through a second optical fiber; the first optical fiber is a bare optical fiber, and the second optical fiber is tightly wound on the component body; The reflected light of the first Faraday rotator and the second Faraday rotator returns along the original optical path respectively, and is coupled to the half-reflecting half-mirror through the optical fiber coupler; the half-reflecting half-mirror reflects the returned coupled reflected light to the analyzer; A speaker is placed within a specified distance range from the part body to play a sound signal to a second optical fiber tightly wound around the part body; a silencer is set within a specified distance range from the first optical fiber to silence the first optical fiber.

7. The optical fiber polarization characteristic detection device based on acoustic waves according to claim 6, characterized in that: The laser is used for emitting a laser beam with a wavelength of 632.8 nm.

8. The optical fiber polarization characteristic detection device based on acoustic waves according to claim 6, characterized in that: The speaker is used to play sound signals of different frequencies, and the frequency range of the sound signal includes high frequency and low frequency.

9. The optical fiber polarization characteristic detection device based on acoustic waves according to claim 6, characterized in that: It also includes a camera and a computer; the polarizer is connected to the camera and the computer in sequence; the camera is used to receive the polarization information sent by the polarizer and generate a polarization state image, and the computer is used to display the polarization state image.

10. The optical fiber polarization characteristic detection device based on acoustic waves according to claim 6, characterized in that: The component body is fixed on the bottom plate, and the optical fiber is tightly wound on the component body in one direction.

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