A method and apparatus for detecting the polarization characteristics of optical fibers based on acoustic waves.

Abstract

This invention discloses a method and apparatus for detecting the polarization characteristics of optical fibers based on acoustic waves. The method includes: a laser beam emitted from a laser sequentially passes through an aperture stop, a polarizer, and a semi-reflective lens before entering an optical fiber coupler; the optical fiber coupler splits the laser beam into a first beam and a second beam; the first beam is incident on a first Faraday rotator mirror via a first optical fiber; the second beam is incident on a second Faraday rotator mirror via a second optical fiber; the first optical fiber is a bare fiber, and the second optical fiber is tightly wound around a component; the reflected light from the first and second Faraday rotators returns along the original optical path and is coupled through the optical fiber coupler to the semi-reflective lens; an acoustic signal is played onto the second optical fiber tightly wound around the component, while simultaneously muting the first optical fiber; the semi-reflective lens reflects the returned coupled reflected light to an analyzer to obtain polarization information. This invention is used to detect the influence of acoustic wave frequency on the polarization characteristics of optical fibers, helping to ensure the accuracy of optical path transmission.

Description

Technical Field

[0001] This invention relates to the field of fiber optic sensing technology, and in particular to a method and apparatus for detecting the polarization characteristics of optical fibers based on acoustic waves. Background Technology

[0002] Fiber optic circuits utilize fiber optic sensing technology, which offers high sensitivity, strong resistance to electromagnetic interference, and ease of large-scale multiplexing. In recent years, fiber optic sensing has been widely adopted in engineering applications, including marine exploration, towed detection arrays, and submarine-mounted hull-side detection arrays, all with excellent results.

[0003] Light sources, transmission loss, equipment noise, and photoelectric conversion circuits can all be sources of interference, leading to significant errors in the results. Furthermore, due to their mostly micro-bent structures, the light intensity in fiber optic transmission experiences inherent losses, which also significantly deviates from the results, making them difficult to recover for long-distance sensing. Fiber optic interferometric acoustic sensors offer higher sensitivity but are also quite sensitive to other variables, such as temperature.

[0004] Fiber optic polarization paths avoid the aforementioned problems, offering advantages such as simple optical path, high sensitivity, and easy-to-use components. The core of this technology lies in its ability to convert acoustic signals into detectable changes in polarization information. In this way, information can be acquired across a wide frequency range, from low to high frequencies, forming a polarization image. To achieve full-band information acquisition, the polarization path needs to be able to generate acoustic signals covering both low and high frequencies. This requirement means that the signal generator must have the ability to generate acoustic signals over a broad frequency range to ensure data integrity and reliability.

[0005] Despite its many advantages, fiber optic polarization sensing technology also faces a series of challenges:

[0006] During the detection process, the fiber polarization optical path also requires a series of operations such as signal amplification, filtering, and noise reduction for the entire system, which undoubtedly increases the complexity and cost of implementation. Moreover, 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 optical fibers based on acoustic waves is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

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

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

[0010] The laser beam emitted by the laser passes sequentially through an aperture stop and a polarizer to a semi-reflective lens. The laser beam then enters an optical fiber coupler through the semi-reflective lens, which splits the laser beam into a first beam and a second beam. The first beam is incident on a first Faraday rotator mirror via a first optical fiber, and the second beam is incident on a second Faraday rotator mirror via a second optical fiber. The first optical fiber is a bare optical fiber, and the second optical fiber is tightly wound around the component body.

[0011] The reflected light from the first Faraday rotator and the second Faraday rotator returns along the original optical path and reaches the half-reflective half-lens via the fiber coupler;

[0012] A sound signal is played into the second optical fiber tightly wound around the part, while the first optical fiber is simultaneously muted.

[0013] The semi-reflective lens reflects the returned coupled reflected light to the analyzer to obtain polarization information.

[0014] Preferably, the laser beam emitted by the laser has a wavelength of 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 includes displaying a polarization state image obtained by a camera using the polarization information.

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

[0018] This invention also provides a fiber optic polarization characteristic detection device based on acoustic waves, comprising a laser, an aperture stop, a polarizer, a semi-reflective lens, and a fiber coupler arranged sequentially along the optical path; the laser beam emitted by the laser passes sequentially through the aperture stop and the polarizer to reach the semi-reflective lens, and then passes through the semi-reflective lens into the fiber coupler, which splits the laser beam into a first beam and a second beam; the first beam is incident on a first Faraday rotator mirror via a first optical fiber; the second beam is incident on a second Faraday rotator mirror via a second optical fiber; the first optical fiber is a bare optical fiber, and the second optical fiber is tightly wound around the component body;

[0019] The reflected light from the first Faraday rotator and the second Faraday rotator returns along the original optical path and is coupled to the half-reflective half-lens via the fiber coupler; the half-reflective half-lens reflects the returned coupled reflected light to the analyzer.

[0020] A speaker is placed within a specified distance from the part body to play sound signals to the second optical fiber tightly wound on the part body; a noise reduction device is set within a specified distance from the first optical fiber to perform noise reduction treatment on 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, the frequency range of which includes high and low frequencies.

[0023] Preferably, it further includes a camera and a computer; the analyzer is connected in sequence to the camera and the computer; the camera is used to receive polarization information sent by the analyzer 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 the base plate, and the optical fiber is tightly wound unidirectionally around the component body.

[0025] Compared with existing technologies, it has the following advantages:

[0026] This invention addresses the complexity of the optical path during the aforementioned polarization process. By optimizing the optical fiber polarization characteristics and studying the optical path, it solves the problem of significant errors in existing technologies caused by factors such as light source, transmission loss, equipment noise, and photoelectric conversion circuits. A rationally designed optical path layout ensures the accuracy of optical transmission.

[0027] This invention can not only effectively detect the influence of sound waves on the polarization characteristics of optical fibers, but also obtain images showing changes in polarization characteristics. These effects are visually displayed through images, providing important data support for subsequent research and applications. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely embodiments of the present invention, and those skilled in the art can obtain other drawings based on the provided drawings without creative effort.

[0029] Figure 1 Optical path diagram of the optical fiber polarization characteristic detection method based on acoustic waves provided in the embodiments of the present invention;

[0030] Figure 2 This is a schematic diagram of the structure of the second optical fiber winding component provided in an embodiment of the present invention;

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

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

[0033] Figure 5 Polarization state diagram of an acoustic wave frequency of 528 Hz when the angle of the polarizer is 45°, as provided in an embodiment of the present invention;

[0034] Figure 6 The polarization state diagram of the polarizer with an angle of 45° and an acoustic frequency of 1000 Hz provided in the embodiment of the present invention. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

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

[0037] Laser 1 emits a laser beam that passes sequentially through aperture stop 2 and polarizer 3 to a semi-reflective lens 4. The laser beam then enters fiber coupler 5 through the semi-reflective lens 4, splitting the laser beam into a first beam and a second beam. The first beam is incident on a first Faraday rotator 71 via a first fiber 61, and the second beam is incident on a second Faraday rotator 72 via a second fiber 62. The first fiber 61 is a bare fiber, and the second fiber 62 is tightly wound around the component. The reflected light from the first Faraday rotator 71 and the second Faraday rotator 72 returns along the original optical path and is coupled through fiber coupler 5 to the semi-reflective lens 4. A sound signal is played onto the second fiber 62 tightly wound around the component, while the first fiber 61 is simultaneously muted. The semi-reflective lens 4 reflects the returned coupled reflected light to analyzer 8 to obtain polarization information.

[0038] In this embodiment, the laser beam passes through the polarizer 3 and the semi-reflective lens 4. This optical signal acts on the first optical fiber 61 and the second optical fiber 62. The semi-reflective lens 4 reflects the acoustically processed optical signal. This reflected optical signal passes through the semi-reflective lens 4 to the analyzer 8, and is finally displayed on the computer 10 by the camera 9. This increases the accuracy of the optical path modulation section.

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

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

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

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

[0043] In one embodiment, the second optical fiber 62 is wound from one end of the component body, uniformly wound in a single direction to the surface of the component body, and ends at the other end of the component body. The component body can be a cylinder.

[0044] In one embodiment, a method for noise reduction of the first optical fiber 61 includes: placing the first optical fiber 61 into a soundproof box, filling it with sponge, and sealing the top layer with a heavy rubber cover. Specifically, the first optical fiber 61 can be a fiber optic hydrophone, and another sensing probe of the fiber optic hydrophone can be placed inside the soundproof box.

[0045] In one embodiment, the polarization information is further included by displaying a polarization state image obtained by camera 9.

[0046] In one embodiment, by adjusting the angle of the polarizer in the polarizer 3 (e.g., 0°, 45°), polarization state images under different light intake levels can be obtained.

[0047] A second aspect of this invention also provides an optical fiber polarization characteristic detection device based on acoustic waves, used to perform all the steps of the first aspect of the invention. This includes:

[0048] A laser 1, an aperture stop 2, a polarizer 3, a semi-reflective mirror 4, and an optical fiber coupler 5 are arranged sequentially along the optical path. The laser beam emitted by the laser 1 passes through the aperture stop 2 and the polarizer 3 sequentially to reach the semi-reflective mirror 4. The laser beam then passes through the semi-reflective mirror 4 and enters the optical fiber coupler 5, which splits the laser beam into a first beam and a second beam. The first beam is incident on a first Faraday rotator mirror 71 via a first optical fiber 61; the second beam is incident on a second Faraday rotator mirror 72 via a second optical fiber 62. The first optical fiber 61 is bare. The optical fiber and the second optical fiber 62 are tightly wound around the part body; the reflected light from the first Faraday rotator 71 and the second Faraday rotator 72 return along the original optical path and are coupled to the semi-reflective lens 4 via the optical fiber coupler 5; the semi-reflective lens 4 reflects the returned coupled reflected light to the analyzer 8; a speaker is placed within a specified distance from the part body to play sound signals to the second optical fiber 62 tightly wound around the part body; a noise reduction device is set within a specified distance from the first optical fiber 61 to perform noise reduction treatment on the first optical fiber 61.

[0049] In one embodiment, laser 1 is a He-Ne laser, which 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 focus the laser beam and prevent the beam from diverging.

[0051] In one embodiment, the polarizer 3 consists of a polarizer, and by adjusting the angle of the polarizer (e.g., 0°, 45°), polarization state images under different light intake levels can be obtained.

[0052] In one embodiment, the surface of the semi-reflective mirror 4 facing the polarizer 3 is coated with a high-transmittance film to transmit the laser beam transmitted by the polarizer 3, and the surface of the semi-reflective mirror 4 facing the fiber coupler 5 is coated with a high-reflectance film to reflect the beam transmitted back from the fiber coupler 5 to the analyzer 8.

[0053] In one embodiment, the speaker is used to play sound signals of different frequencies, including high and low frequencies. In this embodiment, the selected sound wave frequencies are 500 Hz and 10000 Hz.

[0054] In one embodiment, the system further includes a camera 9 and a computer 10; a polarizer 8 is connected in sequence to the camera 9 and the computer 10; the camera 9 is used to receive 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 to the base plate, and the optical fiber is tightly wound unidirectionally around the component body. For example... Figure 2 As shown, the upper end of the component 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 component can be a cylinder.

[0056] like Figure 3 The figures show polarization images of the sound wave at a frequency of 528 Hz when the polarizer angle is 0°. Figure (a) shows the polarization image without the sound wave, and Figure (b) shows the polarization image with the sound wave at 528 Hz. It can be seen that the light spot density in the polarization image is slightly reduced.

[0057] like Figure 4 The figures show polarization images of the sound wave at a frequency of 1000 Hz when the polarizer angle is 0°. Figure (a) shows the polarization image without the sound wave, and Figure (b) shows the polarization image with the sound wave at 1000 Hz. It can be seen that the image shape becomes larger and the light spot density decreases.

[0058] like Figure 5 The figures show polarization images of an acoustic wave at a frequency of 528 Hz when the polarizer angle is 45°. Figure (a) shows the polarization image without acoustic wave interference, and Figure (b) shows the polarization image with 528 Hz acoustic wave interference. It can be seen that the light spot density decreases slightly, and the image shape changes slightly.

[0059] like Figure 6 The figures show polarization images of the sound wave at a frequency of 1000 Hz when the polarizer angle is 45°. Figure (a) shows the polarization image without the sound wave, and Figure (b) shows the polarization image with the sound wave at 1000 Hz. It can be seen that the light spot becomes significantly brighter and its shape changes markedly.

[0060] The polarization images reveal that sound waves not only affect the polarization of the laser beam but may also influence its focusing characteristics. Observation of the images shows a visible difference between images with and without incident sound waves, and the vibrations in the 10000 Hz sound wave image are more pronounced than those in the 500 Hz sound wave image when sound waves are incident.

[0061] The present invention provides a detailed description of a method and apparatus for detecting the polarization characteristics of optical fibers based on acoustic waves. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

[0062] In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A method for detecting the polarization characteristics of optical fibers based on acoustic waves, characterized in that, Includes the following steps: The laser beam emitted by the laser passes sequentially through an aperture stop and a polarizer to a semi-reflective lens. The laser beam then enters an optical fiber coupler through the semi-reflective lens, which splits the laser beam into a first beam and a second beam. The first beam is incident on a first Faraday rotator mirror via a first optical fiber, and the second beam is incident on a second Faraday rotator mirror via a second optical fiber. The first optical fiber is a bare optical fiber, and the second optical fiber is tightly wound around the component body. The reflected light from the first Faraday rotator and the second Faraday rotator returns along the original optical path and is coupled to the half-reflective half-lens by the fiber coupler; A speaker is placed within a specified distance from the part body to play sound signals of different frequencies onto the second optical fiber tightly wound on the part body, while simultaneously performing noise reduction on the first optical fiber. The semi-reflective lens reflects the returned coupled reflected light to the analyzer to obtain polarization information, and then displays the polarization state image obtained by the camera.

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

3. The method for detecting the polarization characteristics of optical fibers based on acoustic waves according to claim 1, characterized in that, The frequency range of the sound signal includes high frequency and low frequency.

4. The method for detecting the polarization characteristics of optical fibers 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 intake levels can be obtained.

5. A fiber optic polarization characteristic detection device based on acoustic waves, characterized in that, The system includes a laser, an aperture stop, a polarizer, a semi-reflective mirror, an optical fiber coupler, a camera, and a computer, arranged sequentially along the optical path. The laser beam emitted by the laser passes sequentially through the aperture stop and the polarizer to the semi-reflective mirror. The laser beam then passes through the semi-reflective mirror and enters the optical fiber coupler, which splits the laser beam into a first beam and a second beam. The first beam is incident on a first Faraday rotator mirror via a first optical fiber; the second beam is incident on a second Faraday rotator mirror via a second optical fiber. The first optical fiber is a bare optical fiber, and the second optical fiber is tightly wound around the component body. The reflected light from the first Faraday rotator and the second Faraday rotator returns along the original optical path and is coupled to the half-reflective half-lens via the fiber coupler; the half-reflective half-lens reflects the returned coupled reflected light to the analyzer. A speaker is placed within a specified distance from the part body to play sound signals of different frequencies onto the second optical fiber tightly wound on the part body; a noise reduction device is set within a specified distance from the first optical fiber to perform noise reduction treatment on the first optical fiber; The analyzer is connected in sequence to the camera and the computer; the camera is used to receive polarization information sent by the analyzer and generate a polarization state image, and the computer is used to display the polarization state image.

6. The fiber polarization characteristic detection device based on acoustic waves according to claim 5, characterized in that, The laser is used to emit a laser beam with a wavelength of 632.8 nm.

7. The fiber polarization characteristic detection device based on acoustic waves according to claim 5, characterized in that, The frequency range of the sound signal includes high frequency and low frequency.

8. The fiber polarization characteristic detection device based on acoustic waves according to claim 5, characterized in that, The component body is fixed on the base plate, and the optical fiber is tightly wound unidirectionally around the component body.

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