Optical fiber underwater acoustic-magnetic integrated detection sensor based on diamond nitrogen-vacancy color center

Abstract

The application discloses a fiber underwater acoustic-magnetic integrated detection sensor based on a diamond nitrogen vacancy color center, which comprises a circular bottom plate, a multi-mode optical fiber is inserted and fixed in the middle part of the circular bottom plate through a hole, is used for being connected with an external laser pumping module and a fluorescence receiving module, a system diamond is bonded to the upper surface of the inner end of the multi-mode optical fiber, a microwave antenna is coiled on the side surface of the end of the multi-mode optical fiber, the end of the microwave antenna is inserted and fixed on the circular bottom plate and is used for being connected with an external microwave generating module, a cylindrical support fixed on the circular bottom plate is buckled to the outer side of the inner end of the multi-mode optical fiber, a permanent magnet is fixed on the inner wall of the cylindrical support, and a sound-sensitive diaphragm magnetic material covers the upper surface of the cylindrical support. The application can dynamically detect underwater acoustic signals and magnetic signals in real time, establishes a mapping relationship between underwater acoustic signals and dynamic magnetic fields, and realizes high-sensitivity measurement of underwater target multi-physical field signals.

Description

Technical Field

[0001] This invention relates to the field of underwater acoustic and magnetic field measurement technology, and in particular to an optical fiber underwater acoustic-magnetic integrated detection sensor based on diamond nitrogen vacancy color centers. Background Technology

[0002] Underwater magnetic field and acoustic field sensors are developing rapidly, with broad application prospects in national defense, environmental monitoring, and other fields. However, in complex marine environments, single-physics field measurements suffer from high false alarm probabilities, while integrated multi-physics field detection exhibits low sensitivity and signal cross-interference. Underwater acoustomagnetic integrated sensors can effectively solve the cross-sensitivity problem in integrated multi-physics field detection, improve the sensitivity of integrated multi-physics field detection of underwater targets, and provide technical support for underwater information warfare capabilities. Summary of the Invention

[0003] The purpose of this invention is to provide an optical fiber underwater acoustic-magnetic integrated detection sensor based on diamond nitrogen vacancy color centers, which can dynamically detect underwater acoustic and magnetic signals in real time, establish a mapping relationship between underwater acoustic signals and dynamic magnetic fields, and realize highly sensitive measurement of multi-physics field signals of underwater targets.

[0004] To achieve the above objectives, this invention provides an optical fiber underwater acoustomagnetic integrated detection sensor based on diamond nitrogen-vacancy color centers, comprising a circular base plate, a hole in the center of which is used to insert and fix a multimode optical fiber for connection to an external laser pump module and a fluorescence receiving module, an ensemble diamond bonded to the upper surface of the inner end of the multimode optical fiber, a microwave antenna wound around the side surface of the end of the multimode optical fiber, and the end of the microwave antenna being inserted and fixed to the circular base plate for connection to an external microwave generating module; a cylindrical bracket fixed to the circular base plate is fastened to the outer side of the inner end of the multimode optical fiber, a permanent magnet is fixed to the inner wall of the cylindrical bracket, and the upper surface of the cylindrical bracket is covered with an acoustic diaphragm magnetic material.

[0005] Preferably, two permanent magnets are provided and are installed opposite each other on the side wall of the top of the cylindrical bracket.

[0006] Preferably, the outer side of the cylindrical bracket is covered with a rubber protective layer fixed to the circular base plate.

[0007] Preferably, the input and output ends of the microwave antenna are arranged parallel to the multimode optical fiber.

[0008] Preferably, the method for manufacturing the detection sensor is as follows:

[0009] S1. Use UV adhesive to bond the ensemble diamond to the upper surface of the multimode fiber end, and bend the single microwave antenna so that it is coiled around the end side surface of the multimode fiber.

[0010] S2. Fix the multimode optical fiber and microwave antenna on the circular base plate with through holes, and fix a cylindrical bracket with a diameter smaller than that of the circular base plate on the circular base plate. Cover the upper surface of the cylindrical bracket with an acoustic diaphragm, and fix the permanent magnet on the inner wall of the cylindrical bracket.

[0011] S3. Fix the rubber protective layer that completely covers the entire cylindrical bracket onto the circular base plate to complete the fabrication of the entire detection sensor.

[0012] Therefore, the beneficial effects of the fiber optic underwater acoustomagnetic integrated detection sensor based on diamond nitrogen-vacancy color centers in this invention are as follows:

[0013] (1) The detection sensor of the present invention can realize simultaneous acoustic and magnetic detection, and can realize multi-physics field integrated measurement of underwater targets.

[0014] (2) The detection sensor of the present invention has the characteristics of high signal-to-noise ratio and high sensitivity in detecting acoustic-magnetic signals.

[0015] (3) The detection sensor of the present invention can realize efficient conversion of underwater acoustic signals and magnetic fields, which effectively improves the underwater acoustic signal detection capability.

[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of an embodiment of the fiber optic underwater acoustomagnetic integrated detection sensor based on diamond nitrogen vacancy color centers of the present invention;

[0018] Figure 2 This is a schematic diagram of the structure of a detection system constructed using the detection sensor of the present invention.

[0019] Figure Labels

[0020] 1. Acoustic diaphragm magnetic material; 2. Ensemble diamond; 3. Permanent magnet; 4. Rubber protective layer; 5. Microwave antenna; 6. Multimode fiber; 7. Laser pump module; 8. Fluorescence receiving module; 9. Circular base plate; 10. Cylindrical bracket; 11. 532nm laser; 12. Photodetector; 13. Acousto-optic modulator; 14. Mirror; 15. Filter; 16. Dichroic mirror; 17. Beam splitter; 18. Fiber collimator; 19. Photodetector; 20. Microwave amplifier; 21. Feedback controller; 22. Microwave generator; 23. Lock-in amplifier; 24. Computer. Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0023] Example 1

[0024] For example Figure 1 As shown, the present invention provides an optical fiber underwater acoustomagnetic integrated detection sensor based on diamond nitrogen vacancy color centers, including a circular base plate 9, with a hole in the center of the circular base plate 9 and a multimode optical fiber 6 inserted and fixed therein for connection with an external laser pump module and fluorescence receiving module.

[0025] An ensemble diamond 2 is bonded to the upper surface of the inner end of the multimode fiber 6. A single microwave antenna 5 is coiled around the side surface of the end of the multimode fiber 6. The input and output ends of the microwave antenna 5 are bent at a certain angle and connected to the coiled part in the middle, so that the input and output ends of the microwave antenna 5 can be arranged parallel to the multimode fiber 6. The end of the microwave antenna 5 is inserted and fixed on the circular base plate 9 for connection with the external microwave generating module.

[0026] A cylindrical bracket 10, fixed to a circular base plate 9, is fastened to the outer side of the inner end of the multimode optical fiber 6. A permanent magnet 3 is fixed to the inner wall of the cylindrical bracket 10. In this embodiment, two permanent magnets 3 are provided, installed opposite each other on the side wall of the top of the cylindrical bracket 10. The upper surface of the cylindrical bracket 10 is covered with an acoustic-sensitive diaphragm magnetic material 1. The acoustic-sensitive diaphragm magnetic material 1 employs a composite structure of acoustic-sensitive thin-film magnetic materials, such as an iron-cobalt (FeCo) magnetostrictive sensitive film, a Pt / Co multilayer film with perpendicular magnetic anisotropy, or a TbFeCo thin film, etc. By replacing the acoustic-sensitive diaphragm magnetic material 1 on the detection sensor, magnetic field detection with different intensity ranges and sensitivities can be achieved.

[0027] In addition, the cylindrical bracket 10 in this embodiment is also covered with a rubber protective layer 4 fixed on the circular base plate 9 to protect the internal structure of the detection sensor.

[0028] The method for manufacturing this detection sensor is as follows:

[0029] S1. Use UV adhesive to bond the ensemble diamond 2 to the upper surface of the end of the multimode fiber 6, and bend the single microwave antenna 5 so that it is coiled around the end side surface of the multimode fiber 6.

[0030] S2. Fix the multimode fiber 6 and microwave antenna 5 on the circular base plate 9 with through holes, and fix a cylindrical bracket 10 with a diameter smaller than that of the circular base plate 9 on the circular base plate 9. Cover the upper surface of the cylindrical bracket 10 with acoustic diaphragm magnetic material 1, and fix a permanent magnet 3 on the inner wall of the cylindrical bracket 10.

[0031] S3. Fix the rubber protective layer 4, which completely covers the entire cylindrical bracket 10, onto the circular base plate 9 to complete the fabrication of the entire detection sensor.

[0032] like Figure 2 As shown, in use, the 532nm laser 11 emits a 532nm green laser, the laser power is initially adjusted by the acousto-optic modulator 13, and then the green laser passes through the reflector 14 and the dichroic mirror 16 to change the direction of laser propagation.

[0033] Next, the laser beam is split into two paths by beam splitter 17. One path is received by photodetector 19, and the result is input to feedback controller 21. Feedback controller 21 is connected to acousto-optic modulator 13 via a control terminal to adjust the output laser power, thereby ensuring that the laser power emitted by the laser is stable and meets the preset value. The other path is coupled into multimode fiber 6 through fiber collimator 18. The optical path is transmitted along multimode fiber 6 to the detection sensor. The NV color center of the ensemble diamond 2 in the detection sensor is affected by factors such as laser excitation and external magnetic field strength, generating a red fluorescence signal with magnetic field and acoustic field information. The red fluorescence signal returns to fiber collimator 18 along multimode fiber 6 and becomes free light in space. The red fluorescence then passes through beam splitter 17 and dichroic mirror 16. Since green laser light still exists in this part of the optical path, filter 15 is used to remove the green light. Finally, the red laser is received by photodetector 12, and the data is sent to lock-in amplifier 23.

[0034] Microwave generator 22 generates a microwave signal, which is then amplified by microwave amplifier 20 and transmitted to microwave antenna 5. Microwave generator 22 also sends a reference signal to lock-in amplifier 23, which demodulates the two received signals and sends the demodulation result to computer 24 for display. Computer 24 is also connected to feedback controller 21 and microwave generator 22, allowing software settings for this microwave signal parameter.

[0035] The working principle is as follows:

[0036] The energy levels of the NV color center of ensemble diamond 2 consist of a ground state and an excited state, both of which are spin triplet states. The ground state 3A2 is composed of ms=0 and ms=±1 states. In the absence of a magnetic field, the spin triplet state ms=±1 is degenerate. At room temperature, a zero-field split of D=2.87 GHz exists between ms=0 and ms=±1. Population transfer between the ms=0 and ms=±1 states can be achieved by applying an external microwave field. This can be accomplished by generating a microwave signal using a microwave generator 22, amplifying the signal using a microwave amplifier 20, and radiating the microwave signal onto the NV color center of ensemble diamond 2 using a microwave antenna 5 to control the transition between the two states.

[0037] Under 532nm laser pumping, the NV center transitions from the ground state 3A2 spin state to the excited state 3E, and then decays back to the 3A2 state through two pathways. One pathway involves the NV center directly returning to the 3A2 state from the excited state by emitting fluorescence. The other pathway involves the NV center returning to the ground state from the excited state through singlet states 1A1 and 1E, without fluorescence generation. Therefore, the spin state and energy level spacing of the NV center can be obtained by observing changes in fluorescence intensity, thus enabling magnetic field measurement.

[0038] The detection sensor incorporates a flexible acoustic diaphragm magnetic material 1. When the sensor is submerged underwater, the underwater acoustic signal vibrations cause the acoustic diaphragm magnetic material 1 to vibrate in the same manner. The magnetic field strength also changes accordingly. Since the fluorescence intensity produced by the NV color center of the ensemble diamond 2 varies with different magnetic field strengths, underwater acoustic and magnetic field detection can be achieved by detecting changes in fluorescence intensity signals. The fluorescence intensity signal detected by the photodetector 19 in the fluorescence receiving module is sent to the lock-in amplifier 23 for demodulation to obtain the current magnetic field strength. Finally, the data is transmitted to the demodulation system in the computer 24 to further separate the acoustic-magnetic aliasing signals, thus obtaining independent acoustic and magnetic field signals.

[0039] Therefore, the present invention employs the above-mentioned fiber optic underwater acoustic-magnetic integrated detection sensor based on diamond nitrogen vacancy color centers, which can dynamically detect underwater acoustic signals and magnetic signals in real time, establish a mapping relationship between underwater acoustic signals and dynamic magnetic fields, and realize highly sensitive measurement of multi-physics field signals of underwater targets.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An optical fiber underwater acoustomagnetic integrated detection sensor based on diamond nitrogen-vacancy color centers, characterized in that: The device includes a circular base plate with a central opening for inserting and fixing a multimode optical fiber for connection to an external laser pump module and fluorescence receiving module. An ensemble diamond is bonded to the upper surface of the inner end of the multimode optical fiber, and a microwave antenna is coiled around the side surface of the end of the multimode optical fiber. The end of the microwave antenna is inserted and fixed to the circular base plate for connection to an external microwave generating module. A cylindrical bracket, fixed to the circular base plate, is fastened to the outer side of the inner end of the multimode optical fiber. A permanent magnet is fixed to the inner wall of the cylindrical bracket, and the upper surface of the cylindrical bracket is covered with an acoustically sensitive diaphragm magnetic material. Two permanent magnets are provided and are installed opposite each other on the side wall of the top of the cylindrical bracket; The outer side of the cylindrical bracket is covered with a rubber protective layer that is fixed to the circular base plate; The input and output ends of the microwave antenna are arranged parallel to the multimode optical fiber; The method for manufacturing this detection sensor is as follows: S1. Use UV adhesive to bond the ensemble diamond to the upper surface of the multimode fiber end, and bend the single microwave antenna so that it is coiled around the end side surface of the multimode fiber. S2. Fix the multimode optical fiber and microwave antenna on the circular base plate with through holes, and fix a cylindrical bracket with a diameter smaller than that of the circular base plate on the circular base plate. Cover the upper surface of the cylindrical bracket with an acoustic diaphragm, and fix the permanent magnet on the inner wall of the cylindrical bracket. S3. Fix the rubber protective layer that completely covers the entire cylindrical bracket onto the circular base plate to complete the fabrication of the entire detection sensor; The laser beam is split into two paths by a beam splitter. One path is received by a photodetector, and the result is input to a feedback controller. The feedback controller is connected to an acousto-optic modulator via a control terminal to adjust the output laser power, thereby ensuring that the laser power emitted by the laser is stable and meets the preset value. The other path is coupled into the multimode fiber through an optical fiber collimator. The optical path is transmitted along the multimode fiber to the detection sensor. The NV color center of the ensemble diamond in the detection sensor is excited by the laser and affected by the strength of the external magnetic field, generating a red fluorescence signal with magnetic field and acoustic field information. The red fluorescence signal returns to the optical fiber collimator along the multimode fiber and becomes free light in space. The red fluorescence then passes through the beam splitter and dichroic mirror, and a filter is used to remove the green laser. Finally, the red laser is received by the photodetector, and the data is sent to the lock-in amplifier. When the detection sensor is placed underwater, the underwater acoustic signal vibration causes the magnetic material of the acoustic diaphragm to vibrate in the same regular pattern, and the magnitude of the magnetic field also changes accordingly. Since the fluorescence intensity generated by the NV color center of the ensemble diamond varies with different magnetic field intensities, the underwater acoustic field and magnetic field are detected by detecting the change in fluorescence intensity signal. The fluorescence intensity signal detected by the photodetector in the fluorescence receiving module is sent to the lock-in amplifier for demodulation to obtain the current magnetic field intensity. Finally, the data is transmitted to the demodulation system in the computer to obtain independent acoustic field and magnetic field signals.

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