A magnetic field detection device, system, and method based on NV color centers

Abstract

The application relates to a magnetic field detection device, system and method based on NV color centers. The device comprises a diamond NV color center sensing unit, a laser excitation module for generating excitation laser and exciting NV color centers in the diamond NV color center sensing unit, a microwave excitation module for generating a microwave magnetic field and applying the microwave magnetic field to the NV color centers, a signal detection branch for receiving fluorescence signals generated after the NV color centers are excited and converting the fluorescence signals into detection electric signals, a reference detection branch for receiving transmission laser signals and converting the transmission laser signals into reference electric signals, and a signal processing module for receiving the detection electric signals and the reference electric signals respectively, calculating noise signals represented by the reference electric signals according to the detection electric signals and the reference electric signals, removing the noise signals from the detection electric signals, and obtaining a magnetic field signal of a to-be-detected magnetic field where the magnetic field detection device is located. The application can improve the signal-to-noise ratio and measurement accuracy of weak magnetic field signals.

Description

Technical Field

[0001] This application relates to the field of quantum precision measurement technology, and in particular to a magnetic field detection device, system and method based on NV color centers. Background Technology

[0002] Magnetic field detectors, also known as magnetometers, can sense the Earth's magnetic field, artificial magnetic fields, and magnetic fields generated by magnetic objects, and convert the magnetic field signals into voltage or current outputs to measure the magnetic field. Currently, magnetic field detectors based on NV (Nitrogen-Vacancy) color centers in diamond crystals are attracting much attention due to their high sensitivity, high spatial resolution, and room temperature operation capability.

[0003] However, in practical applications, the power fluctuations of the laser irradiating the NV color center are directly converted into fluorescence intensity fluctuations, which drown out the weak magnetic field signal. Furthermore, the circuit noise of the front-end photoelectric conversion circuit introduces interference. Traditional detection structures have difficulty distinguishing between noise signals and real magnetic field signals, resulting in limited noise reduction effects and the need to improve magnetic field detection performance. Summary of the Invention

[0004] Therefore, it is necessary to provide a magnetic field detection device, system, and method based on NV color centers that can effectively remove noise signals.

[0005] In a first aspect, this application provides a magnetic field detection device based on NV color centers, comprising:

[0006] A diamond NV color center sensing unit, wherein the diamond NV color center sensing unit includes an NV color center;

[0007] A laser excitation module is used to generate an excitation laser and direct the excitation laser into the diamond NV color center sensing unit to excite the NV color centers;

[0008] A microwave excitation module is used to generate a microwave magnetic field and apply the microwave magnetic field to the NV color center;

[0009] The signal detection branch is used to receive the fluorescence signal generated after the NV color center is excited, and convert the fluorescence signal into a detection electrical signal;

[0010] The reference detection branch is used to receive the transmitted laser signal transmitted by the excitation laser to the outside of the diamond NV color center sensing unit, and convert the transmitted laser signal into a reference electrical signal;

[0011] The signal processing module is used to receive the detection electrical signal and the reference electrical signal respectively, calculate the noise signal represented by the reference electrical signal based on the detection electrical signal and the reference electrical signal, and then remove the noise signal from the detection electrical signal to obtain the magnetic field signal of the magnetic field to be measured where the magnetic field detection device is located.

[0012] In one embodiment, the signal detection branch includes:

[0013] A fluorescent filter is used to block the excitation laser and also to allow the fluorescence signal to pass through, so as to output the fluorescence signal generated by the NV color center under excitation.

[0014] A signal photodetector is used to convert the fluorescence signal into a detection electrical signal.

[0015] In one embodiment, the reference detection branch includes:

[0016] A laser filter is disposed opposite to the laser excitation module, and the diamond NV center sensing unit is disposed between the laser filter and the laser excitation module. Both the diamond NV center sensing unit and the laser filter are located in the optical path extension direction of the laser excitation module. The laser filter is used to block the fluorescence signal and also to transmit the transmitted laser signal transmitted by the excitation laser to the outside of the diamond NV center sensing unit, so as to output the transmitted laser signal.

[0017] A reference photodetector is used to convert the transmitted laser signal into a reference electrical signal.

[0018] In one embodiment, the signal processing module includes:

[0019] A detection signal amplification unit is used to amplify the detection electrical signal to obtain an amplified detection electrical signal;

[0020] A reference signal amplification unit is used to amplify the reference electrical signal to obtain an amplified reference electrical signal;

[0021] The main control unit is used to calculate the noise signal represented by the reference electrical signal based on the amplified detection electrical signal and the amplified reference electrical signal, and then remove the noise signal from the detection electrical signal to obtain the magnetic field signal of the magnetic field to be measured where the magnetic field detection device is located.

[0022] The detection signal amplification unit and the reference signal amplification unit have the same structure.

[0023] In one embodiment, the emission direction of the microwave magnetic field generated by the microwave excitation module is perpendicular to the designated crystal axis direction of the diamond NV color center sensing unit, and the magnetic field direction of the magnetic field to be measured is parallel to the designated crystal axis direction of the diamond NV color center sensing unit.

[0024] In one embodiment, the excitation laser generated by the laser excitation module is emitted in a horizontal direction and enters the diamond NV color center sensing unit from the side; correspondingly, the light-inlet end of the signal detection branch is disposed on any end face of the diamond NV color center sensing unit, and the light-inlet direction of the signal detection branch is perpendicular to the light-outlet direction of the laser excitation module.

[0025] In one embodiment, the microwave excitation module is disposed on the other end face of the diamond NV color center sensing unit, and the microwave excitation module is disposed opposite to the light-inlet end of the signal detection branch.

[0026] Secondly, this application provides a magnetic field detection system based on NV color centers, including a probe integrating any of the magnetic field detection devices described above.

[0027] Thirdly, this application provides a magnetic field detection method based on NV color centers, including:

[0028] The laser excitation module is driven to generate an excitation laser, which is then directed into the diamond NV color center sensing unit to excite the NV color centers in the diamond NV color center sensing unit.

[0029] The microwave excitation module is driven to generate a microwave magnetic field, which is then applied to the NV color center.

[0030] The signal detection branch receives the fluorescence signal generated after the NV color center is excited, and converts the fluorescence signal into a detection electrical signal through the signal detection branch;

[0031] The reference detection branch receives the transmitted laser signal transmitted by the excitation laser to the outside of the diamond NV color center sensing unit, and converts the transmitted laser signal into a reference electrical signal through the reference detection branch.

[0032] The detection electrical signal and the reference electrical signal are received respectively, and the noise signal represented by the reference electrical signal is calculated based on the detection electrical signal and the reference electrical signal. Then, the noise signal is removed from the detection electrical signal to obtain the magnetic field signal of the current magnetic field to be measured.

[0033] In one embodiment, the noise signal characterized by the reference electrical signal is calculated based on the detected electrical signal and the reference electrical signal, including:

[0034] Calculate the cross-correlation function between the detected electrical signal and the reference electrical signal;

[0035] Based on the cross-correlation function and the reference electrical signal, the noise signal characterized by the reference electrical signal is obtained.

[0036] The aforementioned magnetic field detection device, system, and method based on NV color centers construct a dual-path collaborative optical detection structure based on a signal detection branch and a reference detection branch. The signal detection branch acquires fluorescence detection signals carrying magnetic field signals and laser intensity noise, while the reference detection branch acquires transmitted laser signals characterizing laser intensity noise in real time. A signal processing module then processes the output electrical signals from the signal detection branch and the reference detection branch to achieve accurate identification and removal of noise signals. Based on this, the present invention overcomes the technical bottleneck of traditional single-path detection structures being unable to distinguish between noise signals and real magnetic field signals. It can not only effectively suppress laser intensity noise introduced by laser power fluctuations but also simultaneously suppress circuit common-mode noise, significantly reducing the noise floor of magnetic field detection, thereby significantly improving the detection signal-to-noise ratio and measurement accuracy of weak magnetic field signals. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a structural block diagram of a magnetic field detection device in one embodiment;

[0039] Figure 2 This is a flowchart of a magnetic field detection method in another embodiment.

[0040] Explanation of reference numerals in the attached figures: 101-Diamond NV color center sensing unit; 102-Laser excitation module; 103-Microwave excitation module; 104-Fluorescent filter; 105-Signal photodetector; 106-Laser filter; 107-Reference photodetector; 108-Detection signal amplification unit; 109-Reference signal amplification unit; 110-Main control unit. Detailed Implementation

[0041] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0042] Unless otherwise defined, 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 application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0043] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0044] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0045] This application was made by the inventor based on his understanding and research into the following issues:

[0046] The working principle of magnetic field detection devices based on NV centers is usually to use laser to irradiate the NV centers in diamond crystals to generate fluorescence signals, and to use microwave fields to control the ground state spin energy level of the NV centers. The external magnetic field to be measured will induce Zeeman splitting of the spin energy level of the NV centers, and the corresponding spin resonance frequency will shift regularly with the magnetic field strength. By analyzing the resonance frequency shift corresponding to the fluorescence signal, the parameters of the magnetic field to be measured can be calculated.

[0047] However, in practical applications, fluctuations in laser power are directly converted into fluctuations in fluorescence intensity, which can drown out weak magnetic field signals. Furthermore, thermal noise, 1 / f noise (flicker noise), and power supply ripple in the front-end photoelectric conversion circuit can introduce interference. Traditional single-channel detection structures struggle to distinguish between noise signals and real magnetic field signals.

[0048] Existing technology, such as publication number CN122172081A, discloses a wide-field magnetic imaging system and fault detection method based on diamond nitrogen-vacancy color centers (NV centers). The system includes: a laser excitation unit for generating and forming a uniform excitation light field to irradiate the diamond NV center sensing unit; a fluorescence collection and imaging unit for collecting the fluorescence emitted by the NV centers and forming a wide-field fluorescence image, including an objective lens, a filter, and a camera; a signal processing and control unit electrically connected to the laser excitation unit and the fluorescence collection and imaging unit, for controlling the system timing and processing the intensity information of the wide-field fluorescence image to invert the two-dimensional distribution map of the magnetic field to be measured; and a reference optical path module for real-time monitoring of laser power fluctuations and providing compensation and correction signals to the signal processing and control unit. This prior art compensates for the influence of laser fluctuations on the fluorescence measurement results through the reference optical path module. Through research and analysis, the inventors of this application found that the reference optical path in the relevant prior art is only used to monitor laser power fluctuations and lacks consideration for circuit noise. Furthermore, in practical applications, fluorescence signals are mixed into the reference optical path, and the prior art does not remove these mixed fluorescence signals, resulting in limited noise reduction effect on magnetic field signals and difficulty in further improving the accuracy of magnetic field detection.

[0049] Therefore, this application discloses a magnetic field detection device, system and method based on NV color centers, which has good noise reduction effect, can effectively remove laser noise and circuit common mode noise, and significantly improve magnetic field detection performance.

[0050] like Figure 1As shown, one embodiment provides a magnetic field detection device based on NV color centers, including a diamond NV color center sensing unit 101, a laser excitation module 102, a microwave excitation module 103, a signal detection branch, a reference detection branch, and a signal processing module. The light-emitting end of the laser emission module faces the light-incoming end of the diamond NV color center sensing unit 101. The microwave excitation module 103 is located close to the diamond NV color center sensing unit 101, and the direction of the microwave magnetic field it generates is perpendicular to the principal axis direction of the NV color center. The diamond NV color center sensing unit 101 has two light-emitting ends, including a detection light-emitting end and a reference light-emitting end. The light-incoming end of the signal detection branch is located close to the detection light-emitting end, and the light-incoming end of the reference detection branch is located close to the reference light-emitting end. The signal output ends of the signal detection branch and the reference detection branch are both electrically connected to the signal processing module. In this embodiment, the diamond NV color center sensing unit 101 includes NV color centers; the laser excitation module 102 is used to generate an excitation laser and to direct the excitation laser into the diamond NV color center sensing unit 101 to excite the NV color centers; the microwave excitation module 103 is used to generate a microwave magnetic field and to apply the microwave magnetic field to the NV color centers; the signal detection branch is used to receive the fluorescence signal generated after the NV color centers are excited and to convert the fluorescence signal into a detection electrical signal; the reference detection branch is used to receive the transmitted laser signal transmitted by the excitation laser to the outside of the diamond NV color center sensing unit 101 and to convert the transmitted laser signal into a reference electrical signal; the signal processing module is used to receive the detection electrical signal and the reference electrical signal respectively, and to calculate the noise signal characterized by the reference electrical signal based on the detection electrical signal and the reference electrical signal, and then remove the noise signal from the detection electrical signal to obtain the magnetic field signal of the magnetic field to be measured where the magnetic field detection device is located.

[0051] Among them, the diamond NV color center sensing unit 101 uses a diamond crystal with NV color centers. The NV color center is an atomic-scale defect inside the diamond crystal, which is formed by a nitrogen atom replacing a carbon atom and forming a vacancy in the adjacent position. This structure allows the diamond crystal to control the electron spin through optics and microwaves, so as to achieve high-sensitivity measurement of physical quantities such as magnetic field, electric field, and temperature.

[0052] The laser excitation module 102, also known as a laser, is a device that generates laser light through population inversion and an optical resonant cavity, used to generate excitation laser light to excite NV color centers. In this embodiment, the laser excitation module 102 uses a 520nm semiconductor laser, which can efficiently match the absorption peak of the NV color center in the 510-540nm band. This achieves ground-state spin polarization and fluorescence excitation efficiency comparable to mainstream 532nm solid-state lasers with lower power consumption and smaller size, thereby significantly improving the compactness and integration of the magnetic field detection device.

[0053] The microwave excitation module 103, also known as a microwave excitation source or microwave excitation component, is used to generate and transmit a microwave magnetic field of a specific frequency and power to drive the ground state electron spin of the NV color center in the diamond NV color center sensing unit 101 to undergo a resonant transition, causing a sudden drop in fluorescence intensity (ODMR effect, also known as Optically Detected Magnetic Resonance). It mainly consists of a microwave source, a microwave amplifier, a microwave circulator, and a microwave antenna. In this embodiment, the microwave excitation module 103 uses an existing printed circuit board (PCB) antenna.

[0054] The signal detection branch is the main detection branch in this application, used to receive fluorescence signals including ODMR (Optically Detected Magnetic Resonance) signals, laser intensity noise (RIN), and circuit noise, such as fluorescence signals in the range of 650-800 nm, and convert them into detection electrical signals. The ODMR signal is the original spectral signal containing magnetic field signals. The reference detection branch is a slave detection branch set independently of the signal detection branch in this application, used to receive the transmitted laser signal containing laser intensity noise and circuit noise transmitted to the diamond NV color center sensing unit 101 by the excitation laser, and convert it into a reference electrical signal. Both the signal detection branch and the reference detection branch can realize the acquisition and photoelectric conversion processing of a certain optical signal.

[0055] In this embodiment, since the electrical signals acquired by the two detection branches are both modulated by the intensity of the same laser source, and the noise of the two circuits is highly correlated, the noise signal can be calculated by calculating the cross-correlation of the two electrical signals. Based on adaptive filtering or a differential algorithm, this noise signal can be removed from the detected electrical signal to extract a pure magnetic field signal. Specifically, the signal processing module is a circuit module that processes the electrical signals. It can acquire the noise signal represented by the reference electrical signal, including laser intensity noise and circuit noise, based on the detected electrical signal and the reference electrical signal, and remove it from the detected electrical signal to obtain a pure magnetic field signal, thereby achieving accurate detection of the magnetic field to be measured.

[0056] Specifically, in this embodiment, the signal processing module calculates the noise signal represented by the reference electrical signal based on the detected electrical signal and the reference electrical signal, including: first, calculating the cross-correlation function between the detected electrical signal and the reference electrical signal; then, obtaining the noise signal represented by the reference electrical signal based on the cross-correlation function and the reference electrical signal. Specifically, the common-mode noise signal, including laser intensity noise and circuit noise, is extracted using the cross-correlation function. In this embodiment, the result of multiplying the cross-correlation function and the reference electrical signal is used as the noise signal, and this noise signal is removed from the detected electrical signal to obtain the final magnetic field signal.

[0057] The detection electrical signal transmitted by the signal detection branch at time t can be expressed as:

[0058] S A (t)=S mag (t)+N Laser (t)+N circuit (t);

[0059] In the formula, S mag (t) represents the fluorescence conversion electrical signal corresponding to the ODMR signal containing the magnetic field signal, N Laser (t) represents the laser noise electrical signal corresponding to the laser intensity noise transmitted to the fluorescence signal, N circuit (t) represents the circuit noise electrical signal corresponding to the circuit noise, used to characterize the thermal noise and shot noise of the circuit itself.

[0060] The reference electrical signal transmitted by the reference probe branch at time t can be expressed as:

[0061] S B (t)≈N Laser (t)+N circuit (t);

[0062] The cross-correlation function between the detected electrical signal and the reference electrical signal calculated by the signal processing module can be expressed as R. AB The final magnetic field signal detected at time t can be expressed as:

[0063] S final (t)≈S A (t)-R AB *S B (t).

[0064] In the magnetic field detection device based on NV color centers disclosed in this embodiment, a dual-path collaborative optical detection structure is constructed based on a signal detection branch and a reference detection branch. The signal detection branch collects fluorescence detection signals carrying magnetic field signals and laser intensity noise, while the reference detection branch collects transmitted laser signals characterizing laser intensity noise in real time and uses them as reference signals. The signal processing module then processes the output electrical signals of the signal detection branch and the reference detection branch to achieve accurate identification and elimination of noise signals. Based on this, this embodiment breaks through the technical bottleneck of traditional single-path detection structures that cannot distinguish between noise signals and real magnetic field signals. It can not only effectively suppress laser intensity noise introduced by laser power fluctuations, but also simultaneously suppress circuit common-mode noise, significantly reducing the noise floor of magnetic field detection. This significantly improves the detection signal-to-noise ratio and measurement accuracy of weak magnetic field signals, and the sensitivity can approach the shot noise limit. It solves the technical defects of existing technologies where the noise reduction dimension is single and weak magnetic field signals are easily submerged by noise signals.

[0065] In one embodiment, the signal detection branch includes a fluorescent filter 104 and a signal photodetector 105. The light-inlet end of the fluorescent filter 104 is positioned close to the light-outlet end of the diamond NV color center sensing unit 101, and the light-inlet end of the signal photodetector 105 is positioned close to the light-outlet end of the fluorescent filter 104. The signal output end of the signal photodetector 105 is electrically connected to a signal processing module. The fluorescent filter 104 is used to block the excitation laser and also to transmit the fluorescence signal to output the fluorescence signal generated by the excited NV color center; the signal photodetector 105 is used to convert the fluorescence signal into a detection electrical signal.

[0066] The excitation laser refers to high-energy monochromatic light of a specific wavelength emitted by the laser excitation module 102, used to pump the NV color center from the ground state to the excited state. The fluorescence signal refers to the longer-wavelength light signal carrying spin state information released when the NV color center spontaneously transitions from the excited state back to the ground state; its intensity directly encodes the magnitude of the magnetic field to be measured. The fluorescence filter 104 is used to accurately separate the excitation laser emitted from the detection light end of the diamond NV color center sensing unit 101 from the fluorescence signal emitted by the NV color center, and to transmit the fluorescence signal to improve the signal-to-noise ratio and the accuracy of magnetic field detection. It typically includes an excitation filter, a dichroic mirror, and an emission filter. Although the fluorescence filter 104 blocks the excitation laser, the fluorescence intensity is proportional to the power of the excitation laser. If the laser power fluctuates, the fluorescence intensity will also fluctuate, resulting in the fluorescence signal still containing laser noise, i.e., laser intensity noise. The signal photodetector 105 is a photodetector used to convert the fluorescence signal into an electrical signal, such as a photodiode.

[0067] In this embodiment, the specific structure of the signal detection branch is disclosed. By setting a fluorescent filter 104, the excitation laser is cut off and the NV color center fluorescence signal is selectively transmitted. This avoids the interference of stray light from the excitation laser on the fluorescence detection signal, ensuring that the detection electrical signal collected by the signal photodetector 105 is mainly the fluorescence response signal carrying the magnetic field signal. This effectively improves the purity of the detection electrical signal and provides a reliable original signal basis for subsequent noise and magnetic field signal calculations, further ensuring the accuracy of the magnetic field detection results.

[0068] In one embodiment, the reference detection branch includes a laser filter 106 and a reference photodetector 107. The light-inlet end of the laser filter 106 is positioned close to the reference light-outlet end of the diamond NV color center sensing unit 101, and the light-inlet end of the reference photodetector 107 is positioned close to the light-outlet end of the laser filter 106. The signal output end of the reference photodetector 107 is electrically connected to a signal processing module. The laser filter 106 is positioned opposite to the laser excitation module 102, and the diamond NV color center sensing unit 101 is positioned between the laser filter 106 and the laser excitation module 102. Both the diamond NV color center sensing unit 101 and the laser filter 106 are located in the optical path extension direction of the laser excitation module 102. The laser filter 106 is used to cut off the fluorescence signal and also to transmit the transmitted laser signal transmitted by the excitation laser to the outside of the diamond NV color center sensing unit 101, thereby outputting a transmitted laser signal. The reference photodetector 107 is used to convert the transmitted laser signal into a reference electrical signal.

[0069] The laser filter 106 is used to separate the excitation laser and fluorescence signal emitted from the detection end of the diamond NV color center sensing unit 101, and to obtain the transmitted laser signal by passing through the excitation laser. At this time, since the transmitted laser signal itself does not carry the ODMR signal (the ODMR signal is mainly encoded in the quenching of fluorescence, and the absorption change of the transmitted light is very small and usually negligible), the transmitted laser signal mainly includes laser noise and circuit noise. Based on this, subsequent noise suppression can be achieved. The reference photodetector 107 is a photodetector used to convert the transmitted laser signal into an electrical signal.

[0070] In this embodiment, the specific structure of the reference detection branch is disclosed. The diamond NV color center sensing unit 101 is used to isolate the optical path between the laser excitation module 102 and the laser filter 106. In conjunction with the laser filter 106, the fluorescence signal is cut off and the transmitted laser is selectively transmitted, so that the reference electrical signal collected by the reference photodetector 107 only contains laser intensity noise, avoiding crosstalk of magnetic field signals. This can solve the problem that the existing reference optical path is prone to mixed with fluorescence signals, resulting in noise compensation distortion, and is conducive to improving the accuracy of subsequent noise removal processing.

[0071] It should be noted that in this embodiment, the combined arrangement of the fluorescent filter 104 and the laser filter 106 enables the physical separation of the fluorescent signal and the transmitted laser signal, ensuring the accuracy and stability of subsequent noise suppression.

[0072] In one embodiment, the signal processing module includes a detection signal amplification unit 108, a reference signal amplification unit 109, and a main control unit 110. The detection signal amplification unit 108 and the reference signal amplification unit 109 have the same structure. The signal input terminal of the detection signal amplification unit 108 is electrically connected to the signal output terminal of the signal photodetector 105, and the signal input terminal of the reference signal amplification unit 109 is electrically connected to the signal output terminal of the reference photodetector 107. The signal output terminals of both the detection signal amplification unit 108 and the reference signal amplification unit 109 are electrically connected to the main control unit 110. The detection signal amplification unit 108 amplifies the detection electrical signal to obtain an amplified detection electrical signal. The reference signal amplification unit 109 amplifies the reference electrical signal to obtain an amplified reference electrical signal. The main control unit 110 calculates the noise signal represented by the reference electrical signal based on the amplified detection electrical signal and the amplified reference electrical signal, and then removes the noise signal from the detection electrical signal to obtain the magnetic field signal of the magnetic field to be measured at the location of the magnetic field detection device.

[0073] The detection signal amplification unit 108 and the reference signal amplification unit 109 employ identical electrical signal amplification circuits. If a transimpedance amplifier is used, both can utilize operational amplifiers and feedback resistor networks with the same signal. Alternatively, the detection signal amplification unit 108 and the reference signal amplification unit 109 can employ a high-gain voltage amplifier circuit based on a combination of AC coupling and lock-in amplification technology. The transimpedance amplifier directly converts the weak electrical signal output from the photodetector into a voltage while simultaneously performing low-noise amplification, achieving an extremely high signal-to-noise ratio over a wide dynamic range, laying the foundation for accurate signal processing by the back-end main control unit 110. If the main control unit 110 uses an FPGA (Field Programmable Gate Array), it offers higher integration, stronger logic functions, and greater flexibility, while also being low-cost, low-power, and high-performance, thus improving the sensitivity of magnetic field detection.

[0074] In this embodiment, by setting up a detection signal amplification unit 108 and a reference signal amplification unit 109 with identical structures, the amplification gain, circuit thermal noise, 1 / f noise, and power supply ripple interference of the two signals can be made highly consistent. This ensures that the circuit noise introduced by the two signal amplification units has a high common-mode similarity, so that the circuit noise can be synchronously eliminated in subsequent correlation calculations. This solves the technical problem of neglecting circuit noise suppression in the prior art, and achieves dual suppression of laser intensity noise and circuit noise, further reducing the noise floor of magnetic field detection and improving the accuracy of magnetic field detection.

[0075] In one embodiment, the emission direction of the microwave magnetic field generated by the microwave excitation module 103 is perpendicular to the designated crystal axis direction of the diamond NV color center sensing unit 101, and the magnetic field direction of the magnetic field to be measured is parallel to the designated crystal axis direction of the diamond NV color center sensing unit 101.

[0076] The specified crystal axis direction of the diamond NV color center sensing unit 101 can also be called the direction of the principal axis. The principal axis specifically refers to the symmetry axis of the nitrogen-vacancy defect inside it, that is, the 111 crystal direction connecting the nitrogen atom and the adjacent vacancy. Specifically, the diamond NV color center sensing unit 101 has 4 equivalent 111 axes. In practical applications, any one of the axes can be arbitrarily selected as the current principal axis.

[0077] In this embodiment, the spatial positional matching relationship between the microwave magnetic field direction, the magnetic field to be measured direction, and the specified crystal axis direction of the NV color center is defined. That is, the microwave magnetic field direction is perpendicular to the specified crystal axis direction, and the magnetic field to be measured direction is parallel to the specified crystal axis direction. Based on this, the response effect of Zeeman splitting of the spin energy level of the NV color center can be maximized, effectively enhancing the contrast of the ODMR signal, making the fluorescence signal change characteristics corresponding to the magnetic field change more significant, improving the response sensitivity and resolution of this embodiment to weak magnetic field changes, and optimizing the dynamic response characteristics of magnetic field detection.

[0078] In one embodiment, the excitation laser generated by the laser excitation module 102 is emitted in a horizontal direction and is laterally incident into the diamond NV color center sensing unit 101; correspondingly, the light-inlet end of the signal detection branch is disposed on any end face of the diamond NV color center sensing unit 101, and the light-inlet direction of the signal detection branch is perpendicular to the light-outlet direction of the laser excitation module 102.

[0079] In this embodiment, an orthogonal optical path layout with side-pumped laser incidence and vertical fluorescence acquisition is defined. The side-pumped laser incidence allows the excitation laser to be fully coupled and excited within the diamond NV color center sensing unit 101. The vertically arranged signal detection optical path can collect fluorescence signals radiated from the NV color centers in all directions over the maximum range. At the same time, the orthogonal optical path structure can reduce the probability of stray light from the excitation laser entering the signal detection branch from a physical perspective, improve the fluorescence signal acquisition efficiency and signal quality, simplify the subsequent noise reduction difficulty, and this structural layout is more compact, which is conducive to the miniaturization and integration of the magnetic field detection device.

[0080] In one embodiment, the microwave excitation module 103 is disposed on the other end face of the diamond NV color center sensing unit 101, and the microwave excitation module 103 is disposed opposite to the light-inlet end of the signal detection branch.

[0081] Specifically, such as Figure 1 As shown, as an example, the main axis of the diamond NV center sensing unit 101 is vertically arranged, and the direction of the magnetic field to be measured is vertically upward; the laser emission module is arranged on one side of the diamond NV center sensing unit 101, and the laser emission direction of the laser emission module is perpendicular to the main axis direction, and the excitation laser generated by it is horizontally incident into the diamond NV center sensing unit 101; the light-inlet end of the signal detection branch is arranged above or to the side above the diamond NV center sensing unit 101, and the fluorescence signal generated after the NV center is excited is emitted upward and received by the signal detection branch; the light-inlet end of the reference detection branch is arranged on the side of the diamond NV center sensing unit 101 away from the laser emission module, and the remaining laser after the excitation laser passes through the diamond NV center sensing unit 101 can be received by the reference detection branch; the microwave excitation module 103 is arranged below the diamond NV center sensing unit 101, and the direction of the microwave magnetic field is perpendicular to the main axis direction.

[0082] In this embodiment, a mounting structure is defined in which the microwave excitation module 103 and the signal detection branch are arranged opposite to each other, so that the microwave excitation module 103 is set close to the diamond NV color center sensing unit 101. This can shorten the microwave transmission distance, reduce microwave loss, achieve efficient coupling between the microwave magnetic field and the NV color center, and ensure the stable control effect of microwave on the spin energy level of the NV color center. At the same time, this structure can further reduce the overall size of the magnetic field detection device, adapt to the needs of micro probe integration, and thus improve the portability of the magnetic field detection device.

[0083] In another embodiment, this application discloses a magnetic field detection system based on NV color centers, including a probe integrated with any of the aforementioned magnetic field detection devices.

[0084] In this embodiment, the magnetic field detection probe, which integrates the aforementioned magnetic field detection device, enables the probe to simultaneously possess the dual-channel noise reduction effect of the magnetic field detection device. This overcomes the limitations of traditional NV color center magnetic field detection equipment, which is bulky and inconvenient to deploy. It can be adapted to various complex application scenarios such as biological magnetic field measurement, portable geological exploration, and precision industrial testing, which greatly expands the application scope of NV color center magnetic field detection equipment.

[0085] In yet another embodiment, such as Figure 2 As shown, this application discloses a magnetic field detection method based on NV color centers, which is executed by the signal processing module in the aforementioned magnetic field detection device. The specific steps include:

[0086] Step S201: Drive the laser excitation module 102 to generate an excitation laser and direct the excitation laser into the diamond NV color center sensing unit 101 to excite the NV color centers in the diamond NV color center sensing unit 101.

[0087] Step S202: Drive the microwave excitation module 103 to generate a microwave magnetic field and apply the microwave magnetic field to the NV color center.

[0088] Step S203: The fluorescence signal generated after the NV color center is excited is received by the signal detection branch, and the fluorescence signal is converted into a detection electrical signal by the signal detection branch.

[0089] Step S204: The transmitted laser signal transmitted to the diamond NV color center sensing unit 101 by the excitation laser is received by the reference detection branch, and the transmitted laser signal is converted into a reference electrical signal by the reference detection branch.

[0090] Step S205: Receive the detection electrical signal and the reference electrical signal respectively, calculate the noise signal represented by the reference electrical signal based on the detection electrical signal and the reference electrical signal, and then remove the noise signal from the detection electrical signal to obtain the magnetic field signal of the magnetic field to be measured where the magnetic field detection device is located.

[0091] In this embodiment, a magnetic field detection method corresponding to the aforementioned magnetic field detection device is disclosed. The method uses a signal processing module to drive a laser excitation module 102 to achieve laser excitation, drives a microwave excitation module 103 to perform microwave control, performs simultaneous acquisition of dual-channel signals based on the signal detection branch and the reference detection branch, and extracts and removes noise signals. Thus, noise signals and real magnetic field signals are separated according to the differential characteristics of the dual-channel signals, and a stable output of highly accurate magnetic field detection results is achieved. This method solves the problems of insufficient noise suppression and low magnetic field measurement accuracy of traditional single-channel detection schemes from a methodological perspective.

[0092] In one embodiment, step S205, calculating the noise signal represented by the reference electrical signal based on the detected electrical signal and the reference electrical signal, includes:

[0093] Step S2051: Calculate the cross-correlation function between the detected electrical signal and the reference electrical signal.

[0094] Step S2052: Based on the cross-correlation function and the reference electrical signal, obtain the noise signal represented by the reference electrical signal.

[0095] The detection electrical signal transmitted by the signal detection branch at time t can be expressed as:

[0096] S A (t)=S mag (t)+N Laser (t)+N circuit (t);

[0097] In the formula, S mag (t) represents the fluorescence conversion electrical signal corresponding to the ODMR signal containing the magnetic field signal, N Laser (t) represents the laser noise electrical signal corresponding to the laser intensity noise transmitted to the fluorescence signal, N circuit (t) represents the circuit noise electrical signal corresponding to the circuit noise, used to characterize the thermal noise and shot noise of the circuit itself.

[0098] The reference electrical signal transmitted by the reference probe branch at time t can be expressed as:

[0099] S B (t)≈N Laser (t)+N circuit (t);

[0100] The cross-correlation function between the detected electrical signal and the reference electrical signal calculated by the signal processing module can be expressed as R. AB The final magnetic field signal detected at time t can be expressed as:

[0101] S final (t)≈S A (t)-R AB *S B (t).

[0102] In this embodiment, by utilizing the strong correlation between the detected electrical signal and the reference electrical signal, the laser intensity noise and circuit common-mode noise components are extracted, enabling dynamic and adaptive solution of the noise signal. Compared with fixed parameter noise reduction, this embodiment can adaptively cancel noise interference caused by laser power fluctuations and temperature changes, as well as circuit noise interference introduced by the front-end circuit. No manual calibration is required, which can effectively improve the stability and environmental adaptability of the magnetic field detection system, while improving noise reduction accuracy and magnetic field detection reliability.

[0103] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0104] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A magnetic field detection device based on NV color centers, characterized in that, include: A diamond NV color center sensing unit (101) includes NV color centers; The laser excitation module (102) is used to generate an excitation laser and direct the excitation laser into the diamond NV color center sensing unit (101) to excite the NV color center; The microwave excitation module (103) is used to generate a microwave magnetic field and apply the microwave magnetic field to the NV color center; The signal detection branch is used to receive the fluorescence signal generated after the NV color center is excited, and convert the fluorescence signal into a detection electrical signal; The reference detection branch is used to receive the transmitted laser signal transmitted by the excitation laser to the outside of the diamond NV color center sensing unit (101), and convert the transmitted laser signal into a reference electrical signal; The signal processing module is used to receive the detection electrical signal and the reference electrical signal respectively, calculate the noise signal represented by the reference electrical signal based on the detection electrical signal and the reference electrical signal, and then remove the noise signal from the detection electrical signal to obtain the magnetic field signal of the magnetic field to be measured where the magnetic field detection device is located.

2. The magnetic field detection device according to claim 1, characterized in that, The signal detection branch includes: A fluorescent filter (104) is used to block the excitation laser and to transmit the fluorescent signal so as to output the fluorescent signal generated by the excitation of the NV color center; A signal photodetector (105) is used to convert the fluorescence signal into a detection electrical signal.

3. The magnetic field detection device according to claim 1, characterized in that, The reference detection branch includes: A laser filter (106) is disposed opposite to the laser excitation module (102), and the diamond NV color center sensing unit (101) is disposed between the laser filter (106) and the laser excitation module (102). Both the diamond NV color center sensing unit (101) and the laser filter (106) are located in the optical path extension direction of the laser excitation module (102). The laser filter (106) is used to block the fluorescence signal and also to transmit the transmitted laser signal transmitted by the excitation laser to the outside of the diamond NV color center sensing unit (101) so as to output the transmitted laser signal. A reference photodetector (107) is used to convert the transmitted laser signal into a reference electrical signal.

4. The magnetic field detection device according to claim 1, characterized in that, The signal processing module includes: The detection signal amplification unit (108) is used to amplify the detection electrical signal to obtain an amplified detection electrical signal; The reference signal amplification unit (109) is used to amplify the reference electrical signal to obtain an amplified reference electrical signal; The main control unit (110) is used to calculate the noise signal represented by the reference electrical signal based on the amplified detection electrical signal and the amplified reference electrical signal, and then remove the noise signal from the detection electrical signal to obtain the magnetic field signal of the magnetic field to be measured where the magnetic field detection device is located. The detection signal amplification unit (108) and the reference signal amplification unit (109) have the same structure.

5. The magnetic field detection device according to claim 1, characterized in that, The microwave magnetic field generated by the microwave excitation module (103) is emitted perpendicularly to the designated crystal axis of the diamond NV color center sensing unit (101), and the magnetic field direction of the magnetic field to be measured is parallel to the designated crystal axis of the diamond NV color center sensing unit (101).

6. The magnetic field detection device according to claim 1, characterized in that, The excitation laser generated by the laser excitation module (102) is emitted in a horizontal direction and enters the diamond NV color center sensing unit (101) from the side; correspondingly, the light-inlet end of the signal detection branch is set on any end face of the diamond NV color center sensing unit (101), and the light-inlet direction of the signal detection branch is set perpendicular to the light-outlet direction of the laser excitation module (102).

7. The magnetic field detection device according to claim 6, characterized in that, The microwave excitation module (103) is disposed on the other end face of the diamond NV color center sensing unit (101), and the microwave excitation module (103) is disposed opposite to the light-inlet end of the signal detection branch.

8. A magnetic field detection system based on NV color centers, characterized in that, It includes a probe that integrates a magnetic field detection device as described in any one of claims 1-7.

9. A magnetic field detection method based on NV color centers, characterized in that, include: The laser excitation module (102) is driven to generate an excitation laser, and the excitation laser is directed into the diamond NV color center sensing unit (101) to excite the NV color centers in the diamond NV color center sensing unit (101); The microwave excitation module (103) is driven to generate a microwave magnetic field and the microwave magnetic field is applied to the NV color center; The signal detection branch receives the fluorescence signal generated after the NV color center is excited, and converts the fluorescence signal into a detection electrical signal through the signal detection branch; The reference detection branch receives the transmitted laser signal transmitted by the excitation laser to the outside of the diamond NV color center sensing unit (101), and converts the transmitted laser signal into a reference electrical signal through the reference detection branch. The detection electrical signal and the reference electrical signal are received respectively, and the noise signal represented by the reference electrical signal is calculated based on the detection electrical signal and the reference electrical signal. Then, the noise signal is removed from the detection electrical signal to obtain the magnetic field signal of the current magnetic field to be measured.

10. The magnetic field detection method according to claim 9, characterized in that, The noise signal represented by the reference electrical signal is calculated based on the detected electrical signal and the reference electrical signal, including: Calculate the cross-correlation function between the detected electrical signal and the reference electrical signal; Based on the cross-correlation function and the reference electrical signal, the noise signal characterized by the reference electrical signal is obtained.

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