Magnetic sensor probe device based on NV color center

Abstract

The invention relates to a magnetic sensor probe device based on an NV color center, which comprises a PCB substrate, a microwave antenna structure and a half-hole bonding pad, and is characterized in that the microwave antenna structure is fixedly arranged on the surface of one side of the PCB substrate and is used for receiving microwave signals and transmitting microwaves; the half-hole bonding pad is fixedly arranged on the surface of one side of the PCB substrate, the half-hole bonding pad comprises a microwave bonding pad, one end of the microwave bonding pad is connected with the microwave antenna structure, and the other end of the microwave bonding pad extends to a port of the PCB substrate and is used for transmitting microwave signals. The magnetic sensor probe device based on the NV color center is smaller in size and simple in structure.

Description

Technical Field

[0001] This application relates to the field of quantum sensor technology, and in particular to a magnetic sensor probe device based on NV color centers. Background Technology

[0002] Magnetic sensors based on NV (Nitrogen-Vacancy) centers possess high magnetic measurement sensitivity, making them suitable for high-precision magnetic field measurements and demonstrating significant technological development potential. Technically, the magnetic measurement principle of NV centers falls under magnetic resonance imaging (MRI), involving measuring the magnetic resonance frequency of a specific sample under an unknown magnetic field and then calculating the magnetic field strength based on the relationship between the resonance frequency and the magnetic field. Compared to traditional MRI techniques, NV-center-based MRI offers numerous advantages.

[0003] NV color core magnetometers are typically fabricated as a probe + drive controller structure, requiring the probe to maintain high sensitivity while minimizing size and power consumption to achieve near-plug-and-play functionality. Therefore, miniaturized probe design for NV sensors has become a key focus in related industries. However, traditional NV sensor probes are relatively large and structurally complex. Summary of the Invention

[0004] Therefore, it is necessary to provide a magnetic sensor probe device based on NV color centers that has a smaller size and simpler structure.

[0005] This application provides a magnetic sensor probe device based on NV color centers, including:

[0006] PCB substrate;

[0007] A microwave antenna structure is fixedly mounted on one side surface of a PCB substrate and is used to receive microwave signals and transmit microwaves.

[0008] A half-hole pad is fixedly mounted on one side surface of a PCB substrate. The half-hole pad includes a microwave pad, one end of which is connected to a microwave antenna structure, and the other end of which extends to the port of the PCB substrate for transmitting microwave signals.

[0009] In one embodiment, the microwave pad includes a microwave signal pad and a ground pad; one end of the microwave signal pad is connected to the microwave antenna structure, and the other end of the microwave signal pad is used to connect to the microwave driving circuit to receive the microwave signal from the microwave driving circuit; one end of the ground pad is connected to the microwave antenna structure, and the other end of the ground pad is used to ground through the impedance matching resistor of the PCB substrate.

[0010] In one embodiment, the device further includes:

[0011] A laser transmission module is mounted on one side surface of the PCB substrate and is used to emit laser light.

[0012] The fluorescence collection module is fixedly mounted on one side surface of the PCB substrate and located at the geometric center of the microwave antenna structure. It is used to receive the laser and the microwave emitted into space by the microwave antenna structure, and to perform photoelectric conversion on the fluorescence signal of the laser.

[0013] In one embodiment, the laser transmission module includes a laser diode wafer and a chamfered aspherical focusing lens; the laser diode wafer is used to emit laser light to the fluorescence collection module through the chamfered aspherical focusing lens.

[0014] In one embodiment, the fluorescence collection module includes:

[0015] Diamond is disposed on one side of the PCB substrate and located at the geometric center of the microwave antenna structure. It is used to receive the laser and the microwave emitted into space by the microwave antenna structure, and to emit fluorescent signals.

[0016] A photodetector is attached to a diamond via a filter and is used to receive the fluorescence signal filtered by the filter and perform photoelectric conversion.

[0017] In one embodiment, a through-hole is provided on the contact surface between the laser diode wafer and the PCB substrate, the inner wall of the through-hole is covered with a copper layer, and the copper layer is connected to the copper cladding layer on the other side surface of the PCB substrate.

[0018] In one embodiment, a portion of the diamond surface is provided with a reflective film; the portion of the surface includes at least one of the following surfaces: the surface on which the diamond is attached to the filter and the surface on which the diamond faces the laser transmission module.

[0019] In one embodiment, the photodetector includes a photodetector silicon wafer and a silicon wafer mounting plate; the photodetector silicon wafer is fixedly disposed on the silicon wafer mounting plate, and the photosensitive surface of the photodetector silicon wafer is used to press against a diamond through a filter; the silicon wafer mounting plate is used to be fixedly connected to a PCB substrate.

[0020] In one embodiment, the device further includes:

[0021] A temperature sensor connected to a half-hole pad is placed on one side of the PCB substrate to detect the temperature of the laser diode wafer.

[0022] In one embodiment, the half-hole pad further includes:

[0023] The first half-hole pad is used to transmit laser drive signals, the second half-hole pad is used to transmit temperature measurement signals, and the third half-hole pad is used to transmit photoelectric detection signals.

[0024] The aforementioned magnetic sensor probe device based on NV color centers uses a PCB substrate as the structural base of the probe, and a microwave antenna structure is fixedly mounted on one side surface of the PCB substrate for receiving and transmitting microwave signals. A half-hole pad is fixedly mounted on one side surface of the PCB substrate. The half-hole pad includes a microwave pad, one end of which is connected to the microwave antenna structure, and the other end of which extends to the port of the PCB substrate for transmitting microwave signals. That is, the half-hole pad is used as a connector for microwave transmission, thereby reducing the complexity of structural assembly. While ensuring the quality of microwave transmission, it significantly reduces the volume space occupied by the microwave coaxial connector, thus providing a magnetic sensor probe device based on NV color centers with a smaller size and simpler structure. Attached Figure Description

[0025] 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.

[0026] Figure 1 This is a schematic diagram of the structure of a magnetic sensor probe device based on NV color centers in one embodiment;

[0027] Figure 2 This is a schematic diagram of the structure of a magnetic sensor probe device based on NV color centers in one embodiment after the ceramic housing cover has been removed;

[0028] Figure 3 This is a schematic diagram of the port of a magnetic sensor probe device based on NV color centers in one embodiment;

[0029] Figure 4 This is a side view of the crimped connection between the components of a fluorescence collection module in one embodiment;

[0030] Figure 5 This is a schematic diagram of the microwave antenna structure and the diamond structure in one embodiment;

[0031] Figure 6 This is a schematic diagram of the filter and auxiliary structural components in one embodiment;

[0032] Figure 7 This is a schematic diagram of the structure of a photodetector in one embodiment.

[0033] Explanation of reference numerals in the attached drawings: PCB substrate 100, microwave antenna structure 200, half-hole pad 300, ceramic housing 400, fluorescence collection module 500, diamond 510, filter 520, microwave radiating antenna 530, laser diode wafer 600, temperature sensor 700, chamfered aspherical focusing lens 800, long-pass filter 540, auxiliary structural component 550, silicon wafer mounting plate 560, photodetector silicon wafer 570. Detailed Implementation

[0034] 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.

[0035] 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.

[0036] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0037] 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.

[0038] It is understandable that "at least one" refers to one or more, and "multiple" refers to two or more. "At least a part of an element" refers to part or all of an element.

[0039] 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.

[0040] In traditional technologies, magnetic sensors based on NV (Nitrogen-Vacancy) color centers possess high magnetic measurement sensitivity and are suitable for high-precision magnetic field measurement applications, showing significant potential for technological development. Technically, the magnetic measurement principle of NV color centers can be categorized under magnetic resonance imaging (MRI), which involves measuring the magnetic resonance frequency of a specific sample under an unknown magnetic field and then calculating the magnetic field strength based on the relationship between the resonance frequency and the magnetic field. Compared to traditional MRI techniques, NV color center-based MRI technology offers the following advantages:

[0041] Magnetic resonance at NV centers occurs at electronic energy levels, and the absorption peak spectral lines corresponding to the magnetic resonance process are relatively broad (typically in the range of 1 MHz to 10 MHz). Magnetic field changes within the spectral line width can be measured. In contrast, traditional magnetic resonance techniques typically use atomic nuclei as carriers, resulting in narrower spectral line widths (typically below 1 kHz). This imposes significant limitations on the measurement of magnetic field changes and can easily trigger problems such as lock-out.

[0042] The magnetic resonance state of the NV color center can be determined by optical methods. Under the same partial resonance state, this method generates a larger measurement signal amplitude and the measurement accuracy of external detection equipment is higher. In contrast, traditional magnetic resonance technology requires the detection of microwave transmittance to determine the magnetic resonance state. This detection method has low sensitivity and is not suitable for magnetic field measurement.

[0043] Based on the aforementioned differences in characteristics, traditional magnetic resonance (MR) technology is typically used for material analysis. It calculates parameters such as the gyromagnetic ratio of an unknown sample by measuring the resonant magnetic field strength of the unknown sample under a fixed microwave frequency or by measuring the resonant frequency of the unknown sample under a fixed magnetic field, and then infers the sample's specific composition. In contrast, NV centers place a defined NV center spin system under an unknown magnetic field and calculate the magnetic field strength by measuring the microwave resonant frequency, thus achieving magnetic field measurement. In this application context, NV center magnetic sensors are typically fabricated as a probe + drive controller structure, requiring the probe to maintain high sensitivity while minimizing size and power consumption to achieve near-plug-and-play functionality. Therefore, miniaturized probe design for NV sensors has become a key focus in related industries.

[0044] In principle, the magnetic resonance of NV color centers relies on microwave drive, while observing magnetic resonance requires a photodetector to measure changes in the intensity of fluorescence light excited by a laser. In other words, an NV sensor comprises at least three parts: laser drive, microwave drive, and photodetector. Therefore, miniaturization methods for the probe need to be considered from the perspectives of optical design, structural installation and fabrication, and microwave antenna design. For these reasons, modern NV sensor probes typically possess the following characteristics:

[0045] The probe structure is manufactured using CNC machining, which requires high precision in the machining process. Furthermore, it is essentially a non-standard structural component, resulting in high processing costs.

[0046] The probe has multiple optical lenses installed inside, and the lenses are fixed by a mechanical transmission structure, which enables fine adjustment of the lens position. Therefore, the probe is generally large in size.

[0047] The fluorescence acquisition section uses a stacked optical guide structure and a large-area photodetector module to guide the fluorescence from the diamond to the photosensitive surface of the photodetector step by step, which requires a large-area photodetector.

[0048] NV sensor probes employing the above-described structure typically achieve high magnetic measurement sensitivity, but they face limitations in terms of probe size, cost, and assembly complexity. Specifically, small-volume CNC machined parts have higher tolerance requirements, and machining and assembly errors have a more severe impact, significantly reducing probe production yield; small-volume mechanical transmission structures have poor stability, and adjusting and locking the lenses is more difficult, affecting the probe's working life and long-term stability; the combination of a light guide structure and a large-area photodetector results in a large volume, limiting further reduction in sensor size.

[0049] On the other hand, existing NV sensor designs are typically incompatible with PCB mounting and cannot be directly soldered onto a PCB like chips. In principle, NV sensors require the coordination of modules such as laser, microwave, and photoelectric detection. In practice, microwaves are transmitted via coaxial cables, which can be connected using SMA, SMP, and other microwave coaxial connectors. Laser driving and photoelectric signals usually occur as low-frequency currents and can be transmitted using common multi-pin connectors, such as DB9, J30J, aviation connectors, and header pins. Among these, the coaxial connector for microwave transmission is the most disadvantageous for PCB mounting. Specifically, typical PCB soldering packages include DIP, SOP, MSOP, QFN, LCC, and BGA, all of which are through-hole or surface-mount structures, making it impossible to fabricate coaxial pads. Microwave signals propagated along coaxial cables have the most complex requirements for pads, requiring precise control of parameters such as pad width, copper plating thickness, and distance from the pad plane to the ground plane to ensure impedance matching requirements for microwave transmission. In contrast, laser and fluorescence signals only require electrical connections between pads and do not have special requirements. Currently, only coaxial cables can be used to connect to the PCB board; laser-driven and photoelectric detection do not have the above problems. It can be seen that microwave transmission is the main factor affecting the mounting of NV sensors on the PCB.

[0050] Based on the above-mentioned traditional technologies, this application provides a magnetic sensor probe device based on NV color centers, which improves the stability of the assembled probe structure by reducing assembly complexity and production costs, and is compatible with the relevant requirements of PCB mounting.

[0051] Specifically, in this embodiment, a PCB substrate is used as the main structure, and the laser diode wafer, microwave antenna structure, chamfered aspherical focusing lens, diamond, and photoelectric detection module are all mounted on the surface of the PCB substrate and protected by a ceramic shell.

[0052] Furthermore, embodiments of this application reduce the optical path length, thereby reducing the complexity of the optical path and improving its stability. The laser transmission section retains only the laser diode wafer, the chamfered aspherical focusing lens, and the diamond, while the fluorescence collection section retains only the diamond, the filter, and the photodetector silicon wafer. This structural adjustment partially reduces the effectiveness of laser focusing and fluorescence collection, thus having a certain impact on probe performance.

[0053] Furthermore, in order to compensate for the impact of optical path simplification on sensor performance, the embodiments of this application require the addition of some design elements, including: coating the diamond surface and adding a reflector at the rear end to reflect the laser passing through the diamond back to the diamond, thereby increasing the excitation efficiency; coating the sides and bottom of the diamond to reflect the fluorescence emitted from these surfaces into the photodetector, thereby enhancing the fluorescence amplitude.

[0054] Furthermore, in accordance with the design requirements of microwave antennas, this application embodiment selects a material with a low dielectric constant to fabricate the PCB substrate, thereby reducing the substrate thickness and the microstrip line width of the microwave antenna. Taking 4350B Rogers board as an example, the dielectric constant of this material is 3.48, which is smaller than the 4.2~4.7 of commonly used FR4 board. While ensuring impedance matching, the board thickness can be reduced to 0.508mm, and the microstrip line width of the microwave antenna can be controlled to 1.1mm.

[0055] Furthermore, in this embodiment, SMA, SMP and other coaxial connectors are eliminated, and a half-hole pad (also known as a stamp hole pad) is used as the microwave input interface. The microwave circuit is connected by surface mount soldering, and impedance matching is achieved by adjusting the PCB substrate thickness and the width of the half-hole pad, thus realizing small-volume and high-efficiency microwave transmission.

[0056] Furthermore, in this embodiment of the application, in view of the high heat generation characteristics of the laser diode wafer and the microwave impedance matching resistor, a grounding thermal pad is made on the bottom of the laser diode wafer and the grounding surface of the matching resistor. A large area of ​​copper plating and a large number of vias are used to conduct heat to the bottom surface of the PCB substrate, thereby conducting it to the outside of the chip.

[0057] It should be noted that the beneficial effects or technical problems solved by the embodiments of this application are not limited to this one, but may also be other implicit or related problems. For details, please refer to the description of the embodiments below.

[0058] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will be described below with reference to the accompanying drawings.

[0059] In one exemplary embodiment, refer to Figure 1 A magnetic sensor probe device based on NV color centers is provided, comprising:

[0060] PCB substrate 100;

[0061] A microwave antenna structure 200 is fixedly mounted on one side surface of a PCB substrate 100 for receiving microwave signals and transmitting microwaves.

[0062] A half-hole pad 300 is fixedly disposed on one side surface of the PCB substrate 100. The half-hole pad includes a microwave pad, one end of which is connected to the microwave antenna structure 200, and the other end of which extends to the port of the PCB substrate 100 for transmitting microwave signals.

[0063] The half-hole pad can be connected to the microwave circuit using surface mount soldering, similar to the connection method between QFN packaged or BGA packaged chips and external circuits. The half-hole pad can also be called a half-hole microwave pad. The microwave antenna structure includes a microwave radiating antenna.

[0064] The aforementioned magnetic sensor probe device based on NV color centers uses a PCB substrate 100 as the structural base of the probe, and a microwave antenna structure is fixedly disposed on one side surface of the PCB substrate 100 for receiving and transmitting microwave signals. A half-hole pad is fixedly disposed on one side surface of the PCB substrate 100. The half-hole pad includes a microwave pad, one end of which is connected to the microwave antenna structure, and the other end of which extends to the port of the PCB substrate 100 for transmitting microwave signals. That is, the PCB substrate 100 is used as the base and main structure, and a microwave antenna structure 200 and a half-hole pad 300 are disposed on the PCB substrate 100. The half-hole pad 300 is used as the connector for microwave transmission, which is compatible with modern PCB soldering processes. While ensuring the quality of microwave transmission, the volume space occupied by the microwave coaxial connector is significantly reduced, thus providing a magnetic sensor probe device based on NV color centers with a smaller size and simpler structure.

[0065] Further exemplarily, refer to Figure 2The sensor probe device uses a PCB substrate 100 as its main structure. A laser diode wafer, a chamfered aspherical focusing lens, a diamond detector, a filter, a photodetector, and a temperature sensor are bonded to the substrate. A microwave microstrip antenna and a matching resistor are mounted on the PCB substrate 100, thus enabling the measurement of magnetic fields using NV color centers. The PCB dimensions can be designed to be 25.4mm × 15.7mm × 0.508mm. A 1mm thick, 18mm × 11mm × 5mm ceramic or opaque heat-resistant plastic shell is mounted on the upper surface to protect the device from external interference. The ceramic shell can also be referred to as a ceramic protective cover.

[0066] In one exemplary embodiment, the half-hole pad further includes:

[0067] The first half-hole pad is used to transmit laser drive signals, the second half-hole pad is used to transmit temperature measurement signals, and the third half-hole pad is used to transmit photoelectric detection signals.

[0068] Optionally, the sensor probe device has eight half-hole pads, which are used sequentially to transmit laser drive signals, temperature measurement signals, microwave drive signals, and photoelectric detection signals. Specifically, refer to... Figure 3 The PCB ports corresponding to each half-hole pad are as follows:

[0069] LD+: The positive input terminal of the laser diode wafer, from which the laser driving current is input;

[0070] LD-: The inverting input terminal of the laser diode wafer, from which the laser-driven current is output;

[0071] Temp+: The positive input terminal of the temperature sensor, the positive terminal of the power supply voltage that drives the temperature sensor is connected to this pad;

[0072] Temp-: The inverting input terminal of the temperature sensor, the negative terminal of the power supply voltage driving the temperature sensor is connected to this pad;

[0073] PD+: The anode of the photodetector diode. The photodetector operates in reverse bias mode, and the anode needs to be connected to the negative terminal of the drive voltage.

[0074] PD-: Cathode of the photodetector diode. The photodetector operates in reverse bias mode, and the cathode needs to be connected to the positive terminal of the drive voltage.

[0075] MW_in: Microwave input interface. The external microwave drive circuit of the probe inputs microwaves from this interface to the microwave transmitting antenna to drive the diamond NV color center;

[0076] MW_out: Microwave output interface. Microwaves from the microwave transmitting antenna are output from this interface and transmitted to the impedance matching resistor outside the probe; optionally, this interface can be used interchangeably with the MW_in interface.

[0077] In an exemplary embodiment, the microwave pad includes a microwave signal pad and a ground pad; one end of the microwave signal pad is connected to the microwave antenna structure, and the other end of the microwave signal pad is used to connect to the microwave driving circuit to receive the microwave signal from the microwave driving circuit; one end of the ground pad is connected to the microwave antenna structure, and the other end of the ground pad is used to ground through the impedance matching resistor of the PCB substrate.

[0078] Optionally, one end of the microwave transmitting coil is connected to the half-hole pad of the microwave input, and the other end is connected to the impedance matching resistor on the PCB substrate, and grounded through the resistor. Simultaneously, a large area of ​​copper plating is required on the back of the PCB substrate to serve as the ground plane for the microwave circuitry. (Refer to...) Figure 3 Viewed from the outside of the probe, the microwave transmitting antenna has two half-hole pads marked MW_in and MW_out at its two ends. The pad marked MW_in is connected to the microwave input, and the pad marked MW_out is connected to the impedance matching resistor, with the other end of the matching resistor grounded. Optionally, the impedance matching resistor can be installed inside the probe.

[0079] In one exemplary embodiment, the device further includes:

[0080] A laser transmission module is mounted on one side surface of the PCB substrate and is used to emit laser light.

[0081] The fluorescence collection module is fixedly mounted on one side surface of the PCB substrate and located at the geometric center of the microwave antenna structure. It is used to receive the laser and the microwave emitted into space by the microwave antenna structure, and to perform photoelectric conversion on the fluorescence signal of the laser.

[0082] In one exemplary embodiment, refer to Figure 2 The laser transmission module includes a laser diode wafer and a chamfered aspherical focusing lens; the laser diode wafer is used to emit laser light to the fluorescence collection module through the chamfered aspherical focusing lens.

[0083] In one exemplary embodiment, refer to Figure 2 The fluorescence collection module includes:

[0084] Diamond is disposed on one side of the PCB substrate and located at the geometric center of the microwave antenna structure. It is used to receive the laser and the microwave emitted into space by the microwave antenna structure, and to emit fluorescent signals.

[0085] A photodetector is attached to a diamond via a filter and is used to receive the fluorescence signal filtered by the filter and perform photoelectric conversion.

[0086] Optionally, a laser diode wafer, a chamfered aspherical focusing lens, and a diamond are sequentially mounted on the surface of the PCB substrate inside the housing along the long side, and the diamond is mounted at the center of the microwave transmitting coil; one end of the microwave transmitting coil is connected to the half-hole pad of the microwave input, and the other end is connected to the impedance matching resistor of the PCB substrate and grounded through the resistor. At the same time, a large area of ​​copper is provided on the back of the PCB substrate 100 to serve as the ground plane of the microwave circuit.

[0087] In one exemplary embodiment, a through-hole is provided on the contact surface between the laser diode wafer and the PCB substrate. The inner wall of the through-hole is covered with a copper layer, and the copper layer is connected to the copper cladding layer on the other side surface of the PCB substrate.

[0088] Specifically, a via thermal pad is placed beneath the laser diode wafer to facilitate heat dissipation. This via thermal pad has multiple through-holes with an inner copper layer, connecting to a large copper-clad surface on the back of the PCB substrate 100. This allows heat from the laser diode to be conducted to the large copper-clad surface on the back of the PCB substrate.

[0089] In one exemplary embodiment, the device further includes:

[0090] A temperature sensor connected to a half-hole pad is placed on one side of the PCB substrate to detect the temperature of the laser diode wafer.

[0091] Specifically, a temperature sensor is placed next to the laser diode wafer to detect temperature changes in the laser diode and offset the influence of temperature changes on the magnetic measurement results of the magnetic sensor.

[0092] In one exemplary embodiment, a portion of the diamond surface is provided with a reflective film; the portion of the surface includes at least one of the following surfaces: the surface on which the diamond is attached to the filter and the surface of the diamond facing the laser transmission module.

[0093] Specifically, in order to improve laser excitation efficiency and fluorescence collection efficiency and compensate for the performance degradation caused by the simplification of the optical path, this application embodiment coats a high reflectivity film on the diamond surface, retaining only the small facet facing the laser diode and the large facet facing the photodetector for light emission.

[0094] In one exemplary embodiment, refer to Figure 4The photodetector includes a photodetector silicon wafer and a silicon wafer mounting plate; the photodetector silicon wafer is fixedly mounted on the silicon wafer mounting plate, and the photosensitive surface of the photodetector silicon wafer is used to press with diamond through a filter; the silicon wafer mounting plate is used to fix and connect to the PCB substrate, and the microwave radiating antenna is set on the surface of the PCB substrate.

[0095] Specifically, refer to Figure 4 A filter and a photodetector wafer are sequentially mounted on top of the diamond, and the PCB board containing the photodetector wafer is fixed to the PCB substrate to achieve the function of fluorescence collection. During the process, it is ensured that the diamond, filter and photodetector wafer are tightly pressed together and there are no air gaps inside to prevent air gaps from causing fluorescence refraction and reducing fluorescence collection efficiency.

[0096] Optionally, refer to Figure 5 First, the microwave transmitting antenna is grown on the PCB using copper traces, forming... Figure 5 The partially circular structure shown has its two ends connected to half-hole pads marked MW_in and MW_out, respectively, for microwave input and output; a diamond is mounted at the center of the ring to receive microwaves emitted into space by the ring structure. Further, refer to... Figure 6 Above the diamond, a long-pass filter is mounted on the structure to isolate scattered green laser light and allow the red fluorescence emitted by the diamond to pass normally through the filter into the photodetector silicon wafer. To improve the structural strength, U-shaped spacers can be installed around the diamond as auxiliary structural components to support the suspended filter. Further, refer to... Figure 7 Above the filter is a photodetector silicon wafer, which is mounted on a silicon wafer mounting plate. The photosensitive surface of the silicon wafer can be pressed onto the filter to achieve photoelectric conversion of the fluorescence signal.

[0097] In summary, this embodiment of the application uses a PCB substrate 100 as the probe structure base and significantly simplifies the optical path for laser driving and fluorescence collection, reducing the complexity of structural assembly and improving structural stability and long-term consistency. By using a half-hole pad as the microwave transmission connector, it is compatible with modern PCB soldering processes, significantly reducing the volume space occupied by the microwave coaxial connector while ensuring microwave transmission quality. By optimizing the substrate material, the thickness of the PCB substrate 100 is significantly reduced. Combined with the application of thermally conductive holes around the laser diode wafer and microwave impedance matching resistor, the thermal conductivity of the sensor is significantly improved, which enhances the sensor's working performance and long-term reliability. By using a small-area filter and a photodetector silicon wafer, and by pressing diamond, fluorescence collection is achieved by bypassing the traditional light guide structure.

[0098] Therefore, the magnetic sensor probe device based on NV color centers proposed in this application has a significantly smaller volume than the light guide structure, and the photodetector has a smaller area and a higher fluorescence measurement bandwidth, which helps to optimize the AC performance of the NV sensor.

[0099] In the description of this specification, references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0100] 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.

[0101] The above embodiments are merely illustrative of several implementation methods of this application, and their descriptions are relatively specific and detailed, but 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 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 sensor probe device based on NV color centers, characterized in that, include: PCB substrate; A microwave antenna structure is fixedly mounted on one side surface of the PCB substrate for receiving microwave signals and transmitting microwaves. A half-hole pad is fixedly disposed on one side surface of the PCB substrate. The half-hole pad includes a microwave pad. One end of the microwave pad is connected to the microwave antenna structure, and the other end of the microwave pad extends to the port of the PCB substrate for transmitting the microwave signal.

2. The device according to claim 1, characterized in that, The microwave pads include microwave signal pads and ground pads; one end of the microwave signal pad is connected to the microwave antenna structure, and the other end of the microwave signal pad is used to connect to the microwave driving circuit to receive microwave signals from the microwave driving circuit; one end of the ground pad is connected to the microwave antenna structure, and the other end of the ground pad is used to ground through the impedance matching resistor of the PCB substrate.

3. The device according to claim 1, characterized in that, The device also includes: A laser transmission module is disposed on one side surface of the PCB substrate and is used to emit laser light; A fluorescence collection module is fixedly disposed on one side surface of the PCB substrate and located at the geometric center of the microwave antenna structure. It is used to receive the laser and the microwave emitted into space by the microwave antenna structure, and to perform photoelectric conversion on the fluorescence signal of the laser.

4. The device according to claim 3, characterized in that, The laser transmission module includes a laser diode wafer and a chamfered aspherical focusing lens; the laser diode wafer is used to emit the laser light to the fluorescence collection module through the chamfered aspherical focusing lens.

5. The device according to claim 3, characterized in that, The fluorescence collection module includes: Diamond is disposed on one side surface of the PCB substrate and located at the geometric center of the microwave antenna structure. It is used to receive the laser and the microwave emitted into space by the microwave antenna structure and to emit a fluorescent signal. A photodetector is attached to the diamond via a filter and is used to receive the fluorescence signal filtered by the filter and perform photoelectric conversion.

6. The device according to claim 4, characterized in that, A through-hole is provided on the contact surface between the laser diode wafer and the PCB substrate. The inner wall of the through-hole is covered with a copper layer, and the copper layer is connected to the copper cladding layer on the other side surface of the PCB substrate.

7. The device according to claim 5, characterized in that, A reflective film is provided on a portion of the surface of the diamond; the portion of the surface includes at least one of the following surfaces: the surface on which the diamond is attached to the filter and the surface of the diamond facing the laser transmission module.

8. The device according to claim 5, characterized in that, The photodetector includes a photodetector silicon wafer and a silicon wafer mounting plate; the photodetector silicon wafer is fixedly disposed on the silicon wafer mounting plate, and the photosensitive surface of the photodetector silicon wafer is used to press against the diamond through the filter; the silicon wafer mounting plate is used to be fixedly connected to the PCB substrate.

9. The device according to claim 4, characterized in that, The device also includes: A temperature sensor connected to the half-hole pad is disposed on one side surface of the PCB substrate and is used to detect the temperature of the laser diode wafer.

10. The device according to claim 1, characterized in that, The half-hole pad also includes: The first half-hole pad is used to transmit laser drive signals, the second half-hole pad is used to transmit temperature measurement signals, and the third half-hole pad is used to transmit photoelectric detection signals.

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