A diamond nv color center electromagnetic field scanning system based on heterodyne detection

Abstract

This invention relates to an electromagnetic field scanning system for diamond NV centers based on heterodyne detection, belonging to the field of microwave quantum detection technology. It includes a laser pumping module, a fluorescence collection module, a microwave pumping module, a magnetic field control module, and a scanning detection module. The laser pumping module generates a laser to excite the diamond NV centers to emit fluorescence signals. The microwave pumping module generates an injection microwave signal and a reference microwave signal with similar frequencies. The injection microwave signal is injected into the microwave radiation device under test to generate the microwave signal to be measured. The reference microwave signal and the microwave signal to be measured generate a heterodyne mixing signal. The magnetic field control module applies a static magnetic field to the diamond, enabling the diamond NV centers to resonate with the microwave signal to be measured and emit fluorescence response signals. The fluorescence collection module collects the fluorescence signal and obtains the spectrum, which is sent to the control unit. The control unit calculates the microwave signal to be measured based on the spectrum information. This invention solves the problem of the lack of a system solution for applying heterodyne detection to the detection of diamond NV centers in the prior art.

Description

Technical Field

[0001] This invention relates to the field of microwave quantum detection technology, and in particular to an electromagnetic field scanning system for diamond NV color centers based on heterodyne detection. Background Technology

[0002] A diamond NV center (nitrogen vacancy center) is a point defect structure in a diamond crystal. When a light source of a certain energy shines on a diamond NV center, it causes polarization and energy transitions in the internal electron spin state, generating a corresponding fluorescence signal. By applying various physical fields, such as magnetic fields and microwave fields, to modulate and couple diamond, based on its electron spin paramagnetic properties and optical properties, it can be used to measure magnetic fields with high precision. At the same time, because diamond has a stable structure, is non-magnetic, and is easy to process, it can be used to make novel quantum detectors at the micrometer scale. By coupling diamond with various physical fields, it is possible to detect, image, and perform non-destructive testing on the magnetic field radiated from the surface of an RF chip.

[0003] While numerous commercially available diamond NV center detection devices have been successfully deployed, their sensitivity is limited by the decoherence time of the diamond NV centers. This is primarily because existing devices rely on laser irradiation of the diamond to generate fluorescence, followed by scanning the RF chip surface using a permanent magnet to apply a static magnetic field to the diamond NV centers and coupling the fluorescence. When the magnetic field strength on the RF chip surface is weak, it is difficult to acquire effective data. Therefore, industry research has attempted to introduce heterodyne detection based on existing technology to improve the detection sensitivity of current devices. However, to date, no systematic solution has been found to apply heterodyne detection to diamond NV center detection. Summary of the Invention

[0004] Based on the above analysis, the present invention aims to provide an electromagnetic field scanning system for diamond NV centers based on heterodyne detection, in order to solve the problem that there is a lack of system solutions in the prior art that apply heterodyne detection to the detection of diamond NV centers.

[0005] On one hand, embodiments of the present invention provide an electromagnetic field scanning system for diamond NV color centers based on heterodyne detection. The system includes a laser pumping module, a fluorescence collection module, a microwave pumping module, a magnetic field control module, and a scanning detection module.

[0006] The laser pumping module is used to generate laser light and to excite the diamond in the scanning detection module to emit a fluorescent signal through laser excitation.

[0007] The microwave pumping module is used to generate an injected microwave signal and send it to the microwave radiation device under test, and to generate a reference microwave signal and send it to the scanning detection module; the microwave radiation device under test generates the microwave signal to be tested based on the injected microwave signal.

[0008] The magnetic field control module is used to generate a static magnetic field that acts on the diamond in the scanning detection module, so that the diamond NV color center energy level can resonate with the microwave signal to be measured and generate a fluorescence response signal; the frequency of the reference microwave signal is within the resonant frequency band and there is a frequency difference with the microwave signal to be measured.

[0009] The diamond is used to scan the microwave signal to be tested on the surface of the microwave radiation device under test, and can mix the reference microwave signal and the microwave signal to be tested to obtain a heterodyne mixed signal, and generate a fluorescence signal in response to the heterodyne mixed signal.

[0010] The fluorescence collection module is used to collect the fluorescence signal and obtain the spectral information of the fluorescence signal and send it to the control unit;

[0011] The control unit calculates the microwave signal to be measured based on the spectrum information.

[0012] Based on further improvements to the above system, the laser pumping module includes a laser source, a reflector, a dichroic mirror, an optical fiber collimator, and a multimode optical fiber, wherein the diamond is disposed at one end of the multimode optical fiber to form a probe.

[0013] The laser generated by the laser source passes through a reflector and a dichroic mirror in sequence before entering one end of the fiber collimator. It then exits from the other end of the fiber collimator and enters the multimode fiber, from which it is transmitted to the diamond.

[0014] Based on further improvements to the above system, the microwave pumping module includes a first microwave source, a second microwave source, a power amplifier, and a pulse generator, wherein...

[0015] The pulse generator is used to generate pulse trigger signals;

[0016] The first microwave source generates an initial microwave signal based on a pulse trigger signal, and the initial microwave signal is then amplified by a power amplifier to obtain a reference microwave signal.

[0017] The second microwave source generates an injected microwave signal based on a pulse trigger signal.

[0018] Based on further improvements to the above system, the frequency difference between the microwave signal under test and the reference microwave signal does not exceed 1 kHz.

[0019] Based on further improvements to the above system, the magnetic field control module includes a magnet that generates a static magnetic field; the magnet is fixedly placed on one side of the diamond, and the static magnetic field generated by the magnet causes the diamond NV color center and the microwave signal to be measured to resonate.

[0020] Based on further improvements to the above system, the scanning detection module also includes a coil and a displacement stage;

[0021] A diamond is fixed at one end of a multimode optical fiber, above the surface of the microwave radiation device under test, and is used to scan the microwave signal under test.

[0022] The coil is suspended above the surface of the microwave radiation device under test, surrounding the diamond.

[0023] The coil is used to receive and transmit reference microwave signals sent by the microwave pump module.

[0024] The microwave radiation device under test is fixed on one side of the displacement stage, and the displacement stage drives the microwave radiation device under test to move so that the diamond can scan the microwave signal under test at various positions on the surface of the microwave radiation device under test.

[0025] Based on further improvements to the above system, the heterodyne mixing signal is specifically represented as follows:

[0026] In the formula,

[0027] B1 is the reference microwave signal amplitude.

[0028] b1 is the amplitude of the microwave signal to be measured.

[0029] δ is the frequency difference between the reference microwave signal and the microwave signal under test.

[0030] φ is the phase difference between the reference microwave signal and the microwave signal under test.

[0031] T represents time.

[0032] Based on further improvements to the above system, the fluorescence collection module includes a filter, a photodetector, and a spectrum analyzer;

[0033] The fluorescence signal passes sequentially through a multimode fiber, a fiber collimator, and a dichroic mirror before entering a filter. After being filtered by the filter, it enters a photodetector and is converted into an electrical signal. The electrical signal is then transmitted to the control unit after generating spectral information through a spectrum analyzer.

[0034] Based on further improvements to the above system, the control unit is also used to control the timing of the pulse trigger signal and the moving step size, moving trajectory and scanning interval of the displacement stage.

[0035] Based on further improvements to the above system, the magnetic field control module includes a magnet. By adjusting the distance between the magnet and the diamond, the magnitude of the magnetic field applied to the diamond is changed, thereby changing the spectrum of fluorescence emitted by the diamond. When the NV color center of the diamond resonates with the microwave signal to be measured, the magnet is fixed at that position.

[0036] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0037] 1. A probe made of diamond at one end of a multimode optical fiber can be placed as close as possible to the surface of the microwave radiation device under test, thereby enhancing the scanning effect of weak microwave signals under test by shortening the distance between the probe and the device.

[0038] 2. The laser source irradiates the diamond NV color center to produce fluorescence, and then injects laser light into the pulse generator to generate a pulse control signal. The system structure is simpler, and it is convenient for the first microwave source and the second microwave source to generate reference microwave signals and injection microwave signals with similar frequencies based on the pulse control signal, respectively. Under the action of a static magnetic field, the diamond NV color center can resonate with the microwave signal to be measured and the reference microwave signal and generate a fluorescence response signal. After the microwave radiation device under test generates the microwave signal to be measured based on the injection microwave signal, it mixes with the reference microwave signal on the diamond to generate a heterodyne mixing signal. The diamond NV color center generates a fluorescence response signal under the action of the heterodyne mixing signal. This not only enhances the detection sensitivity, but also provides a feasible system scheme for applying heterodyne detection to the detection of diamond NV color centers.

[0039] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0040] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0041] Figure 1 This is a schematic diagram of the system structure according to an embodiment of the present invention.

[0042] Figure label:

[0043] 1-Laser source; 2-Reflector; 3-Divide mirror; 4-Fiber collimator; 5-Multimode fiber;

[0044] 6-Diamond; 7-Filter; 8-Photodetector; 9-Spectrum analyzer; 10-Pulse generator; 11-First microwave source; 12-Power amplifier; 13-Second microwave source; 14-Coil;

[0045] 15-Magnet; 16-Displacement stage; 17-Microwave radiation device under test; 18-Control unit. Detailed Implementation

[0046] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0047] A specific embodiment of the present invention discloses an electromagnetic field scanning imaging system for diamond NV color centers based on heterodyne detection, such as... Figure 1 As shown.

[0048] The system includes a laser pumping module, a fluorescence collection module, a microwave pumping module, a magnetic field control module, and a scanning detection module, wherein...

[0049] The laser pumping module is used to generate laser light and to excite the diamond in the scanning detection module to emit a fluorescent signal through laser excitation.

[0050] The microwave pumping module is used to generate an injected microwave signal and send it to the microwave radiation device under test, and to generate a reference microwave signal and send it to the scanning detection module; the microwave radiation device under test generates the microwave signal to be tested based on the injected microwave signal.

[0051] The magnetic field control module is used to generate a static magnetic field that acts on the diamond in the scanning detection module, so that the diamond NV color center energy level can resonate with the microwave signal to be measured and generate a fluorescence response signal; the frequency of the reference microwave signal is within the resonant frequency band and there is a frequency difference with the microwave signal to be measured.

[0052] The diamond is used to scan the microwave signal to be tested on the surface of the microwave radiation device under test, and can mix the reference microwave signal and the microwave signal to be tested to obtain a heterodyne mixed signal, and generate a fluorescence signal in response to the heterodyne mixed signal.

[0053] The fluorescence collection module is used to collect the fluorescence signal and obtain the spectral information of the fluorescence signal and send it to the control unit;

[0054] The control unit calculates the microwave signal to be measured based on the spectrum information.

[0055] In this embodiment, a laser is generated by a laser pump module to irradiate the diamond NV color center. Specifically, the laser pump module includes a laser source 1, a reflector 2, a dichroic mirror 3, an optical fiber collimator 4, and a multimode optical fiber 5. The diamond 6 is disposed at one end of the multimode optical fiber 5 to form a probe.

[0056] The laser source 1 generates a laser beam that is refracted sequentially by the reflector 2 and the dichroic mirror 3 before entering one end of the fiber collimator 4. The laser beam exits from the other end of the fiber collimator 4 and enters the multimode fiber 5, where it is transmitted to the diamond 6.

[0057] Optionally, a continuous green laser with a wavelength range of 520nm-550nm is selected. After being refracted sequentially by a reflector 2 and then by a dichroic mirror 3, it is incident through an optical fiber collimator 4. The optical fiber collimator 4 is connected to a multimode optical fiber 5. The laser, after passing through the collimator 4, is incident into the connected multimode optical fiber 5. A diamond 6 is disposed at the other end of the multimode optical fiber 5 where the laser is incident. The diamond 6 is a granular diamond crystal containing NV color centers. Preferably, the end of the multimode optical fiber 5 with the diamond 6 is tapered to form a pointed cone structure, and the diamond 6 is bonded to the tip of the cone to form an optical fiber diamond probe. Based on the principle of diamond NV color center scanning magnetic field imaging, laser irradiation of the diamond NV color center induces initial polarization of the electron spin state. After absorbing the energy of the incident light, the diamond NV color center generates a red fluorescence signal with decreasing frequency and amplitude.

[0058] The generated fluorescence signal will be emitted from the diamond 6, and the fluorescence collection module will collect and process the fluorescence signal.

[0059] Specifically, the fluorescence collection module also includes a filter 7, a photodetector 8, and a spectrum analyzer 9;

[0060] The fluorescence signal passes sequentially through a multimode fiber 5, a fiber collimator 4, and a dichroic mirror 3 before entering a filter 7. After being filtered by the filter 7, the signal enters a photodetector 8 and is converted into an electrical signal. The electrical signal then passes through a spectrum analyzer 9 to generate spectral information before being transmitted to a control unit 18.

[0061] Specifically, the fluorescence collection module and the laser pumping module share a dichroic mirror 3, an optical fiber collimator 4, and a multimode optical fiber 5. The generated fluorescence signal is produced by the diamond 6 and then passes in reverse through the multimode optical fiber 5 and the optical fiber collimator 4 before illuminating the dichroic mirror 3. The frequency and wavelength of the fluorescence signal can just pass through the dichroic mirror 3 and are filtered by the filter 7 before being transmitted to the photodetector 8 and converted into an electrical signal. The electrical signal is then transmitted to the spectrum analyzer 9 to generate a spectrum and then transmitted to the control unit 18. The spectrum corresponding to the electrical signal converted from the fluorescence signal can reflect the corresponding frequency and energy distribution of the fluorescence signal. The diamond NV color center electromagnetic field scanning imaging is the observation and imaging of the fluorescence signal spectrum changes caused by the influence of the microwave radiation device 17 under test on the fluorescence signal.

[0062] In this embodiment, an injected microwave signal and a reference microwave signal are generated by a microwave pump module to inject a microwave signal into the microwave radiation device 17 under test to generate the microwave signal to be tested, and the reference microwave signal is used to achieve heterodyne detection to obtain better detection sensitivity.

[0063] Furthermore, the microwave pumping module includes a first microwave source 11, a power amplifier 12, a second microwave source 13, and a pulse generator 10, wherein,

[0064] Pulse generator 10 is used to generate pulse trigger signals;

[0065] The microwave signal generated by the first microwave source 11 is based on a pulse trigger signal to generate an initial microwave signal. The initial microwave signal is then amplified by a power amplifier 12 to obtain a reference microwave signal.

[0066] The microwave signal generated by the second microwave source 13 is based on the pulse trigger signal to generate the injected microwave signal.

[0067] Specifically, the pulse generator 10 generates a pulse trigger signal based on the control command of the control unit 18; the first microwave source 11 and the power amplifier 12 are mainly used to generate a reference microwave signal for heterodyne detection. The first microwave source 11 generates an initial microwave signal after pulse timing control based on the pulse trigger signal. The reference microwave signal obtained after amplifying the power of the initial microwave signal through the power amplifier 12 has a power far exceeding that of the injected microwave signal. The second microwave source 13 generates the injected microwave signal after pulse timing control based on the pulse trigger signal. When the intensity of the microwave signal to be tested generated by the microwave radiation device under test based on the injected microwave signal is very weak, it is difficult to resonate with the fluorescence signal, resulting in poor quality of the scanned microwave signal. In some cases, the signal intensity is too low to resonate with the fluorescence signal, making it undetectable. Therefore, by amplifying the power of the reference microwave signal, the energy of the heterodyne signal after mixing the reference microwave signal and the microwave signal to be tested is enhanced, thereby making the fluorescence signal respond to the enhanced heterodyne mixed signal and improving the detection energy of weak signals.

[0068] The frequency difference between the microwave signal to be tested and the reference microwave signal does not exceed 1 kHz.

[0069] The pulse generator is also used to control laser source 1 to generate pulsed laser light.

[0070] Based on the principle of magnetic field detection of diamond NV color centers, a magnetic field control module is required to apply a magnetic field to diamond 6.

[0071] Furthermore, the magnetic field control module includes a magnet 15 that generates a static magnetic field; the magnet 15 is fixedly disposed on one side of the diamond 6, and the static magnetic field generated by the magnet 15 causes the NV color center of the diamond 6 and the microwave signal to be measured to resonate.

[0072] Furthermore, by adjusting the distance between the magnet 15 and the diamond 6, the magnitude of the magnetic field applied to the diamond 6 is changed, thereby changing the spectrum of fluorescence emitted by the diamond 6. When the NV color center of the diamond 6 resonates with the microwave signal to be measured, the magnet 15 is fixed at that position.

[0073] Specifically, magnet 15 is preferably a permanent magnet. It is positioned on one side of diamond 6, with its plane perpendicular to diamond 6. The purpose is to further modulate diamond 6 using the static magnetic field applied by magnet 15, achieving resonance between the NV color center energy level in diamond 6 and the microwave signal under test. This allows the magnetic field distribution of the radiation device under test to be obtained during scanning. Once set up, the positions of magnet 15 and diamond 6 remain unchanged.

[0074] In order to achieve scanning of the microwave signal under test, a scanning detection module is also required to perform the scanning process.

[0075] Furthermore, the scanning detection module includes a coil 14 and a displacement stage 16;

[0076] Diamond 6 is fixed at one end of multimode optical fiber 5 above the surface of microwave radiation device 17 under test, and is used to scan the microwave signal under test.

[0077] The coil 14 is suspended above the surface of the microwave radiation device 17 under test, surrounding the diamond 6.

[0078] The coil 14 is used to receive and transmit reference microwave signals sent by the microwave pump module.

[0079] The microwave radiation device 17 to be tested is fixed on one side of the displacement stage 16. The displacement stage 16 drives the microwave radiation device 17 to move so that the diamond 6 can scan the microwave signal to be tested at various positions on the surface of the microwave radiation device 17.

[0080] The microwave radiation device under test is placed on the surface of the displacement stage 16, and the diamond is located above the surface of the microwave radiation device under test. Generally, in order to ensure that the microwave signal under test and the NV color center energy level of the diamond 6 resonate, the relative positions of the magnet 15 and the diamond 6 are determined and remain stationary. During the scanning process, the scanning detection is completed by moving the displacement stage 16.

[0081] To obtain better scanning results, the displacement stage 16 is typically moved to a position close enough to the diamond 6, ensuring that the diamond moves along the plane of the displacement stage 16 with a preset step size and preset trajectory, keeping the distance between the diamond 6 and the microwave radiation device 17 under test unchanged. The displacement stage 16 is controlled by the control unit 18.

[0082] Furthermore, the control unit 18 is also used to control the timing of the pulse trigger signal and the moving step size, moving trajectory and scanning interval of the displacement stage 16.

[0083] A coil 14, preferably a circular coil, is arranged around the diamond 6 and suspended above the surface of the microwave radiation device 17 under test, surrounding the diamond 6. The plane of the coil 14 is parallel to the surface of the displacement stage 16 where the microwave radiation device 17 is placed. The coil 14 is connected to a power amplifier 12, receives a reference microwave signal output by the power amplifier 12, and transmits it to the diamond 6. The reference microwave signal and the microwave signal under test are mixed on the diamond 6 to generate a heterodyne mixed signal. The heterodyne mixed signal acts on the NV color center of the diamond 6 and generates a fluorescence signal in response to the heterodyne mixed signal.

[0084] Furthermore, the heterodyne mixer signal is specifically represented as follows:

[0085] In the formula,

[0086] B1 is the reference microwave signal amplitude.

[0087] b1 is the amplitude of the microwave signal to be measured.

[0088] δ is the frequency difference between the reference microwave signal and the microwave signal under test.

[0089] φ is the phase difference between the reference microwave signal and the microwave signal under test.

[0090] t represents time.

[0091] A reference microwave signal is emitted to the diamond 6 via coil 14. The heterodyne mixed signal generated on the diamond 6 by the reference microwave signal and the microwave signal under test is much stronger than that of the microwave signal under test, enabling the diamond 6 to produce a significant response to the heterodyne mixed signal. Since the heterodyne mixed signal includes the parameter characteristics of both the reference microwave signal and the microwave signal under test, the fluorescence signal generated by the diamond 6 in response to the heterodyne mixed signal carries parameter characteristics corresponding to those of the microwave signal under test. The fluorescence signal generated during scanning is converted into spectral information, and the control unit calculates the microwave signal under test based on this spectral information.

[0092] The control unit 18 calculates the microwave signal to be tested based on the spectrum information. Specifically, the control unit 18 parses the fluorescence signal parameters from the spectrum information and then extracts the signal parameters to be tested from the fluorescence signal parameters.

[0093] This embodiment discloses a diamond NV center electromagnetic field scanning imaging system based on heterodyne detection, comprising a laser pumping module, a fluorescence collection module, a microwave pumping module, a magnetic field control module, and a scanning detection module. The laser pumping module generates a laser-excited fluorescence signal emitted by diamond 6 in the scanning detection module. The microwave pumping module generates an injected microwave signal and a reference microwave signal with similar frequencies. The injected microwave signal is sent to the microwave radiation device under test (MDT) to generate the MDT signal. The reference microwave signal is sent to the scanning detection module, and together with the MDT signal, they act on diamond 6 to generate a heterodyne mixing signal, resulting in a higher sensitivity of the generated fluorescence signal to the MDT signal. A static magnetic field applied by the magnetic field control module achieves resonance between the diamond 6 NV center and the MDT signal. The fluorescence collection module collects the fluorescence signal and obtains its spectrum, which is sent to a control unit. The control unit calculates the MDT signal based on the spectrum information. Compared to existing technologies, this embodiment provides a system solution for applying heterodyne detection to diamond NV center detection, which is easy to implement and provides improved detection sensitivity.

[0094] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware, and the program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0095] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A diamond NV color center electromagnetic field scanning imaging system based on heterodyne detection, characterized in that, The system includes a laser pumping module, a fluorescence collection module, a microwave pumping module, a magnetic field control module, and a scanning detection module, wherein... The laser pumping module is used to generate laser light and to excite the diamond in the scanning detection module to emit a fluorescent signal through laser excitation. The microwave pumping module is used to generate an injected microwave signal and send it to the microwave radiation device under test, and to generate a reference microwave signal and send it to the scanning detection module; the microwave radiation device under test generates the microwave signal to be tested based on the injected microwave signal. The magnetic field control module is used to generate a static magnetic field that acts on the diamond in the scanning detection module, so that the diamond NV color center energy level can resonate with the microwave signal to be measured and generate a fluorescence response signal; the frequency of the reference microwave signal is within the resonant frequency band and there is a frequency difference with the microwave signal to be measured. The diamond is used to scan the microwave signal to be tested on the surface of the microwave radiation device under test, and can mix the reference microwave signal and the microwave signal to be tested to obtain a heterodyne mixed signal, and generate a fluorescence signal in response to the heterodyne mixed signal. The fluorescence collection module is used to collect the fluorescence signal and obtain the spectral information of the fluorescence signal and send it to the control unit; The control unit calculates the microwave signal to be measured based on the spectrum information.

2. The electromagnetic field scanning imaging system for diamond NV color centers based on heterodyne detection according to claim 1, characterized in that, The laser pumping module includes a laser source, a reflector, a dichroic mirror, an optical fiber collimator, and a multimode optical fiber, wherein the diamond is disposed at one end of the multimode optical fiber to form a probe; The laser generated by the laser source passes through a reflector and a dichroic mirror in sequence before entering one end of the fiber collimator. It then exits from the other end of the fiber collimator and enters the multimode fiber, from which it is transmitted to the diamond.

3. The electromagnetic field scanning imaging system for diamond NV color centers based on heterodyne detection according to claim 2, characterized in that, The microwave pumping module includes a first microwave source, a second microwave source, a power amplifier, and a pulse generator, wherein... The pulse generator is used to generate pulse trigger signals; The first microwave source generates an initial microwave signal based on a pulse trigger signal, and the initial microwave signal is then amplified by a power amplifier to obtain a reference microwave signal. The second microwave source generates an injected microwave signal based on a pulse trigger signal.

4. The electromagnetic field scanning imaging system for diamond NV color centers based on heterodyne detection according to claim 3, characterized in that, The frequency difference between the microwave signal to be tested and the reference microwave signal does not exceed 1 kHz.

5. The electromagnetic field scanning imaging system for diamond NV color centers based on heterodyne detection according to claim 4, characterized in that, The magnetic field control module includes a magnet that generates a static magnetic field; the magnet is fixedly placed on one side of the diamond, and the static magnetic field generated by the magnet causes the fluorescent signal emitted by the diamond and the microwave signal to be measured to resonate.

6. The electromagnetic field scanning imaging system for diamond NV color centers based on heterodyne detection according to claim 1, characterized in that, The scanning detection module also includes coils and a displacement stage; A diamond is fixed at one end of a multimode optical fiber, above the surface of the microwave radiation device under test, and is used to scan the microwave signal under test. The coil is suspended above the surface of the microwave radiation device under test, surrounding the diamond. The coil is used to receive and transmit reference microwave signals sent by the microwave pump module. The microwave radiation device under test is fixed on one side of the displacement stage, and the displacement stage drives the microwave radiation device under test to move so that the diamond can scan the microwave signal under test at various positions on the surface of the microwave radiation device under test.

7. The electromagnetic field scanning imaging system for diamond NV color centers based on heterodyne detection according to claim 6, characterized in that, The heterodyne mixer signal is specifically represented as follows: In the formula, B1 is the reference microwave signal amplitude. b1 is the amplitude of the microwave signal to be measured. δ is the frequency difference between the reference microwave signal and the microwave signal under test. φ is the phase difference between the reference microwave signal and the microwave signal under test. t represents time.

8. The electromagnetic field scanning imaging system for diamond NV color centers based on heterodyne detection according to claim 7, characterized in that, The fluorescence collection module includes a filter, a photodetector, and a spectrum analyzer; The fluorescence signal passes sequentially through a multimode fiber, a fiber collimator, and a dichroic mirror before entering a filter. After being filtered by the filter, it enters a photodetector and is converted into an electrical signal. The electrical signal is then transmitted to the control unit after generating spectral information through a spectrum analyzer.

9. The electromagnetic field scanning imaging system for diamond NV color centers based on heterodyne detection according to claim 8, characterized in that, The control unit is also used to control the timing of the pulse trigger signal and the movement step size, movement trajectory and scanning interval of the displacement stage.

10. The electromagnetic field scanning imaging system for diamond NV color centers based on heterodyne detection according to claim 5, characterized in that, By adjusting the distance between the magnet and the diamond, the magnitude of the magnetic field applied to the diamond is changed, thereby altering the spectrum of fluorescence emitted by the diamond. When the NV color center of the diamond resonates with the microwave signal to be measured, the magnet is fixed at that position.

Images