Diamond optomagnetic sensor and diamond optomagnetic sensor system

Abstract

A diamond optical magnetic sensor includes: a diamond having a color center with an electron spin, and irradiated with excitation light; and an irradiation section that irradiates the diamond with excitation light of the color center and an electromagnetic wave for magnetic resonance, the irradiation section receiving amplitude-modulated modulated light, a modulation frequency of the modulated light being included in a frequency band of a microwave.

Description

Technical Field

[0001] This disclosure relates to diamond optical-magnetic sensors and diamond optical-magnetic sensor systems. This application claims priority based on Japanese Application No. 2021-059797, filed on March 31, 2021, and invokes all the contents described in the aforementioned Japanese application. Background Technology

[0002] A known optical-magnetic sensor utilizes a diamond NV center (hereinafter referred to as the NV center). When the NV center, composed of nitrogen at a carbon substitution site in diamond and a void adjacent to that nitrogen, becomes negatively charged, its ground state is a triplet state (i.e., spin S = S = 1). When the NV center is excited by light at a wavelength of 532 nm (i.e., green light), it emits fluorescence at a wavelength of 637 nm (i.e., red light). The fluorescence intensity varies depending on the spin state, which is influenced by the magnetic field applied to the NV center and magnetic resonance based on microwaves or radio waves, thus enabling its use as a diamond optical-magnetic sensor.

[0003] The diamond photomagnetic sensor consists of the following: a diamond substrate containing an NV center; an optical system that transmits excitation light from a light source to the NV center; an optical system that focuses fluorescence from the NV center to a photodetector; and a waveguide that transmits microwaves from a power source to the NV center.

[0004] For example, Non-Patent Document 1 discloses a structure in which a diamond sensor is mounted on a coplanar waveguide and microwaves are irradiated. The diamond substrate is rectangular in shape, and excitation light is irradiated from the side of the diamond substrate, while fluorescence is focused from the diamond substrate.

[0005] Existing technical documents

[0006] Non-patent literature

[0007] Non-Patent Document 1: Yuta Masuyama, Yuji Hatano, Takayuki Iwasaki, Mutsuko Hatano, “High-Sensitivity Macroscopic Diamond Magnetometer Using Coplanar Waveguides,” Proceedings of the 79th Autumn Academic Conference of the Chinese Society of Applied Physics (Published: September 5, 2018) Summary of the Invention

[0008] One aspect of this disclosure relates to a diamond photomagnetic sensor comprising: a diamond having a color center with electron spin and being irradiated with excitation light; and an irradiation unit that irradiates the diamond with electromagnetic waves for magnetic resonance, the irradiation unit receiving amplitude-modulated light, the modulation frequency of which is contained in the microwave band.

[0009] Another aspect of this disclosure relates to a diamond optical-magnetic sensor system comprising the aforementioned diamond optical-magnetic sensor, an optical modulation unit that generates modulation light, and a transmission unit that transmits the modulation light, wherein the modulation light is transmitted via the transmission unit and received by the irradiation unit. Attached Figure Description

[0010] Figure 1 This is a block diagram illustrating a diamond optical-magnetic sensor system according to an embodiment of the present disclosure.

[0011] Figure 2 It is a block diagram representing the transmission path of microwaves irradiating diamond and the excitation light.

[0012] Figure 3 It means Figure 1 A block diagram illustrating an example of the structure of the optical power supply unit in a diamond optical-magnetic sensor system.

[0013] Figure 4 This is an example of a structure used to generate a reverse bias voltage, and it represents a representation of... Figure 3 Block diagrams of different structures.

[0014] Figure 5 This is an example of a structure used to generate a reverse bias voltage, and it represents a representation of... Figure 3 as well as Figure 4 Block diagrams of different structures.

[0015] Figure 6 It means Figure 3 A block diagram of an example structure of the resonator shown.

[0016] Figure 7 This is a block diagram representing the optical power supply unit involved in the first modified example.

[0017] Figure 8 This is a block diagram showing the transmission path of microwaves irradiating the diamond and the excitation light in the diamond optical-magnetic sensor system involved in the second modification.

[0018] Figure 9 This is a block diagram illustrating the transmission path of microwaves irradiating the diamond and the excitation light in the diamond optical-magnetic sensor system involved in the third variation.

[0019] Figure 10 This is a block diagram illustrating the transmission path of microwaves irradiating the diamond and the excitation light in the diamond optical-magnetic sensor system involved in the fourth variation.

[0020] Figure 11 This is a schematic diagram showing the structure of the measuring device used in the experiment.

[0021] Figure 12It is a three-dimensional diagram showing the shape of the diamond used in the experiment.

[0022] Figure 13 This is a graph showing the experimental results of transmitting microwaves using optical power.

[0023] Figure 14 This is a graph showing the change in the intensity of fluorescence emitted from the NV center of a diamond.

[0024] Figure 15 This is a graph showing the experimental results of transmitting microwaves via coaxial cable. Detailed Implementation

[0025] [The problem this disclosure aims to solve]

[0026] When using diamond photomagnetic sensors in the measurement of high-voltage electrical equipment, in order to avoid insulation damage from high voltage, it is preferable to ensure insulation isolation from a remote location for the transmission of excitation light, fluorescence, and microwaves.

[0027] Regarding the transmission of excitation light and fluorescence, if optical fiber is used, it is possible to ensure isolation from a remote location. Regarding microwave transmission, it is difficult to ensure isolation in coaxial cable-based transmission, but if transmitting and receiving antennas are used for spatial transmission of radio waves, isolation can be ensured from a remote location.

[0028] When using transmitting and receiving antennas to transmit microwaves in space, the frequency of the microwaves causing NV center magnetic resonance is approximately 3 GHz, and the wavelength of the microwaves in space is approximately 10 cm. Therefore, the receiving antenna also needs to be about 10 cm in size. Since the antenna is made of conductive material, in measurements of high-voltage electrical equipment, it is necessary to ensure insulation isolation and avoid electric field concentration to prevent insulation damage. However, if the receiving antenna is as large as 10 cm, it is difficult to ensure insulation isolation and avoid electric field concentration. In addition, according to the radio wave law, the emission of radio waves into the air is limited to approximately 3 GHz. Due to these constraints, there is a problem that free and flexible measurements cannot be performed.

[0029] Therefore, the purpose of this disclosure is to provide a diamond optical-magnetic sensor and a diamond optical-magnetic sensor system that can be easily used for the measurement of high-voltage electrical equipment.

[0030] [The Effects of This Disclosure]

[0031] According to this disclosure, a diamond optical-magnetic sensor and a diamond optical-magnetic sensor system can be provided that can be easily used for the measurement of high-voltage electrical equipment.

[0032] [Description of embodiments of this disclosure]

[0033] The embodiments described herein are presented in an explanatory manner. At least some of the embodiments described below may be combined arbitrarily.

[0034] (1) The diamond photomagnetic sensor according to the first aspect of this disclosure comprises: a diamond having a color center with electron spin and being irradiated with excitation light; and an irradiation unit that irradiates the diamond with electromagnetic waves for magnetic resonance, the irradiation unit receiving amplitude-modulated modulation light, the modulation frequency of which is contained in the microwave band. Thus, a diamond photomagnetic sensor that can be easily used for the measurement of high-voltage power equipment can be realized. Since the transmission paths of the excitation light, microwaves, and fluorescence transmitted between the diamond photomagnetic sensor and the measuring device can all be constructed of non-metallic components, insulation isolation to avoid insulation damage can be easily ensured in the measurement of high-voltage power equipment, thereby improving the freedom and flexibility of the measurement.

[0035] (2) Alternatively, the irradiation unit may also include a photoelectric conversion unit that converts the modulated light into an electrical signal. Alternatively, the electromagnetic waves used for magnetic resonance may be formed by an electrical signal generated by the photoelectric conversion unit and irradiated onto the diamond. Therefore, the electromagnetic waves (i.e., microwaves) are not transmitted into space using antennas or the like, and are not limited to the radio wave method. Consequently, the measurement environment is not limited to a shielded room, and measurements can be performed in any environment.

[0036] (3) Alternatively, the photoelectric conversion unit may include a photodiode that converts the modulated light into an electrical signal; the irradiation unit may also include a first biasing device that extracts the AC component from the electrical signal generated by the photodiode; or the electromagnetic wave used for magnetic resonance may be formed by the AC component. This allows the diamond photomagnetic sensor to be more compact than the wavelength of the electromagnetic wave used in the measurement (i.e., approximately 10 cm), and can be housed in a spherical or other cornerless housing. Therefore, in the measurement of high-voltage electrical equipment, it is easier to avoid electric field concentration.

[0037] (4) Alternatively, the photoelectric conversion unit may include a photoelectric conversion element that converts a portion of the light including at least one of the light from the emitter, the modulated light, and the excitation light into a potential. Alternatively, the first bias may extract the AC component from the electrical signal by applying a potential generated by the photoelectric conversion element. This enables electrical insulation between the diamond and the light source and the microwave source. Furthermore, the lifespan of the diamond photomagnetic sensor is extended.

[0038] (5) Alternatively, the photoelectric conversion unit may include: a photoelectric conversion element that converts a portion of the light including at least one of the light from the emitter, modulated light, and excitation light into electrical power; and an amplifier that amplifies the output signal of the photodiode or the first bias, or the output signal may be amplified by applying the power generated by the photoelectric conversion element to the amplifier. This enables electrical insulation between the diamond and the light source and the microwave source, allows for the irradiation of the diamond with higher output microwaves, and enables higher sensitivity magnetic detection. Furthermore, the lifespan of the diamond photomagnetic sensor is extended.

[0039] (6) Alternatively, the carrier of the modulation light may have a wavelength different from that of the excitation light. Thus, the modulation light and excitation light can be easily transmitted using the same optical fiber, reducing the number of components.

[0040] (7) Alternatively, the wavelength of the carrier wave of the modulated light may be contained in the near-infrared band. This makes the generation and transmission of the modulated light easier.

[0041] (8) Alternatively, the excitation light may have the same wavelength as the carrier wave of the modulation light, or the modulation light may be generated by amplitude modulation of the excitation light. Thus, only the excitation light needs to be generated, thereby reducing the number of components.

[0042] (9) Alternatively, the modulated light can be a laser. This increases the intensity of the modulated light and allows it to be transmitted to a greater distance.

[0043] (10) Alternatively, modulated light can be output from the laser diode by controlling the drive current of the laser diode to vary with the modulation frequency. Thus, modulated light can be easily generated by direct modulation, and the modulation device can be miniaturized.

[0044] (11) Alternatively, modulated light can be output from the LN element by controlling the LN element with a modulation signal of the modulation frequency. Thus, high-speed modulation is possible, and modulated light with a high modulation frequency can be generated.

[0045] (12) Alternatively, the drive current of the laser diode can be controlled by a second biaser. Thus, modulated light can be easily generated using a laser diode.

[0046] (13) Alternatively, the excitation light can be a laser. Therefore, the excitation light can be easily generated using a laser diode or the like.

[0047] (14) Alternatively, the modulated light can be transmitted via the first optical fiber and received by the irradiation unit. This allows for reliable transmission of the modulated light to the irradiation unit. Furthermore, the diamond optical-magnetic sensor can be safely used in high-voltage electrical equipment.

[0048] (15) Alternatively, the excitation light can be transmitted through a second optical fiber and irradiate the diamond. This ensures reliable transmission of the excitation light to the irradiation unit. Furthermore, the diamond optical-magnetic sensor can be safely used in high-voltage electrical equipment.

[0049] (16) Alternatively, the excitation light can be transmitted via a first optical fiber and irradiate the diamond. Thus, the modulation light and excitation light can be transmitted via a single optical fiber, reducing the number of components and making manufacturing easier.

[0050] (17) Alternatively, the irradiation section may include a resonator, or the diamond may be disposed within the resonator. Thus, electromagnetic waves (i.e., microwaves) can be efficiently irradiated onto the diamond.

[0051] (18) Alternatively, the diamond can be positioned within 5 mm of the photoelectric conversion unit. This allows for the irradiation of the diamond with high-power electromagnetic waves (i.e., microwaves).

[0052] (19) Alternatively, the irradiation unit can irradiate the diamond with the input modulated light as an electromagnetic wave for magnetic resonance. As a result, there is no need for a photoelectric conversion device that converts the modulated light into an electrical signal, which can reduce the number of parts and make manufacturing easier.

[0053] (20) Alternatively, the diamond optical-magnetic sensor may also include a housing portion formed into a smooth shape by a conductive member, or the diamond and the irradiation portion may be housed in the housing portion. Thus, the diamond optical-magnetic sensor can be safely used in high-voltage electrical equipment.

[0054] (21) The diamond photomagnetic sensor system according to the second aspect of this disclosure includes the aforementioned diamond photomagnetic sensor, a light modulation unit that generates modulation light, and a transmission unit that transmits the modulation light. The modulation light is transmitted via the transmission unit and received by the irradiation unit. Therefore, the transmission paths of excitation light, microwaves, and fluorescence transmitted between the diamond photomagnetic sensor and the measuring device can all be constructed of non-metallic components. Thus, in the measurement of high-voltage electrical equipment, it is easy to ensure insulation to avoid insulation damage, thereby improving the freedom and flexibility of measurement. Furthermore, since no antenna or the like is used for spatial transmission of electromagnetic waves (i.e., microwaves), it is not limited to radio wave methods. Therefore, the measurement environment is not limited to a shielded room, and measurements can be performed in any environment.

[0055] [Details of the embodiments disclosed herein]

[0056] In the following embodiments, the same reference numerals are used to refer to the same parts. Their names and functions are also the same. Therefore, detailed descriptions of them will not be repeated.

[0057] Reference Figure 1 The diamond optical-magnetic sensor system 100 disclosed herein includes a diamond 104, a photoelectric conversion unit 106, a transmission unit 108, a modulation signal generation unit 110, an optical modulation unit 112, an optical fiber 114, an excitation light generation unit 120, a wave demultiplexer 122, a focusing unit 124, an optical fiber 126, and a control unit 130. The diamond 104 includes an NV center. Microwaves are supplied to the diamond 104 via optical power supply. The diamond 104, photoelectric conversion unit 106, and transmission unit 108 constitute a diamond optical-magnetic sensor. When measurements are performed using the diamond optical-magnetic sensor system 100 in high-voltage electrical equipment or the like, to avoid electric field concentration, the diamond 104, photoelectric conversion unit 106, and transmission unit 108 are preferably housed in a conductive housing 102, such as a metal. As described below, the control unit 130 controls the modulation signal generation unit 110 and the excitation light generation unit 120 to irradiate the diamond 104 with microwaves and excitation light. The detection unit 128 detects the fluorescence emitted from the diamond 104 and acquires the measurement data. The control unit 130 is implemented by a CPU (Central Processing Unit), microcomputer, or the like.

[0058] The modulation signal generation unit 110, under the control of the control unit 130, generates a signal of a predetermined frequency (i.e., microwave band) and inputs it to the optical modulation unit 112. The optical modulation unit 112 uses the signal supplied from the modulation signal generation unit 110 to amplitude modulate the light of the predetermined frequency, generating and outputting modulated light. That is, the signal output by the modulation signal generation unit 110 is a modulation signal used to generate modulated light. The frequency of the signal output by the modulation signal generation unit 110 is the modulation frequency. The light of the predetermined frequency being modulated is the carrier wave. The modulated light generated by the optical modulation unit 112 is transmitted to the photoelectric conversion unit 106 via the optical fiber 114.

[0059] The photoelectric conversion unit 106 converts the modulated light transmitted via the optical fiber 114 into an electrical signal (i.e., photoelectric conversion) and inputs it to the transmission unit 108. This generates an electrical signal with the frequency of the carrier wave (i.e., the microwave band) from the modulated light and supplies it to the transmission unit 108. The transmission unit 108 amplifies the input electrical signal, i.e., the current, and transmits it to the diamond 104. The electromagnetic waves generated by the electrical signal transmitted in the transmission unit 108 irradiate the diamond 104 for magnetic resonance at the NV center. In other words, the photoelectric conversion unit 106 and the transmission unit 108 constitute the irradiation unit 116, and the modulation signal generation unit 110, the optical modulation unit 112, the optical fiber 114, and the irradiation unit 116 constitute the optical power supply unit 118 for irradiating the diamond 104 with microwaves.

[0060] The excitation light generating unit 120, controlled by the control unit 130, generates and outputs excitation light (i.e., green light) at the NV center. The excitation light generated by the excitation light generating unit 120 is reflected by the beam splitter 122, focused by the beam focusing unit 124, and directed into the optical fiber 126. The beam splitter 122 reflects or transmits the incident light according to its wavelength. The beam splitter 122, for example, is a dichroic mirror, reflecting the green excitation light and allowing red fluorescence to pass through. The optical fiber 126 transmits the input excitation light to the diamond 104. The excitation light then illuminates the diamond 104, emitting fluorescence (i.e., red light) from the NV center of the diamond 104. The fluorescence emitted from the diamond 104 enters the optical fiber 126, is transmitted through the optical fiber 126, and is emitted from the output end of the optical fiber 126. The fluorescence emitted from the output end of the optical fiber 126 is paralleled by the beam focusing unit 124, passes through the beam splitter 122, and enters the detection unit 128. The detection unit 128 detects the intensity of the incident fluorescence. The control unit 130 acquires the signal detected by the detection unit 128 as measurement data. Thus, the diamond optical-magnetic sensor system 100 can measure magnetic fields and the like.

[0061] As described above, in the diamond optical-magnetic sensor system 100, the microwaves irradiating the diamond 104 are powered by light. That is, referring to... Figure 2 Microwaves irradiating the diamond 104 are transmitted as light (i.e., modulated light) through optical fiber 114 to the vicinity of the diamond 104, where they are converted into electromagnetic waves (i.e., microwaves) by electrical signals. Meanwhile, excitation light from the center of the NV is output from the excitation light generation unit 120 and transmitted to the diamond 104 through optical fiber 126. Fluorescence emitted from the center of the NV is transmitted to the detection unit 128 through optical fiber 126. Thus, by using optical power, the transmission paths of excitation light, microwaves, and fluorescence between the diamond optical-magnetic sensor and the measuring device can all be constructed using non-metallic components (e.g., optical fibers). Therefore, in the measurement of high-voltage electrical equipment, it is easy to ensure insulation to avoid insulation damage, thus improving the freedom and flexibility of the measurement.

[0062] The optical power supply unit 118 of the diamond optical-magnetic sensor system 100 is shown in more detail. (Refer to...) Figure 3 Modulation signal generation unit 110 (refer to) Figure 1 It includes VCO 140, attenuator 142, amplifier 144, circulator 146, and terminator 148. Optical modulation unit 112 (see reference) Figure 1 It includes a bias circuit 150, a current source 152, and an LD (laser diode) 154. Fiber optic cable 114 (see reference). Figure 1 Includes optical fiber 156. Photoelectric conversion unit 106 (see reference) Figure 1 The system includes a PD (photodiode) 158, a bias circuit 160, and a voltage source 162. It should be noted that, in cases where amplification of the signal converted by the photoelectric conversion unit 106 is required, the power amplifier may also be included between the PD 158 and the bias circuit 160, or in the stage following the bias circuit 160. Transmission unit 108 (see reference...) Figure 1 It includes a circulator 164, a terminator 166, and a resonator 168.

[0063] VCO 140 generates and outputs an electrical signal with a constant frequency. This constant frequency falls within the microwave band. The output signal of VCO 140 is shaped to a predetermined level by attenuator 142 and amplifier 144 without altering the frequency. Circulator 146 supplies the signal from amplifier 144 to bias 150. A portion of the signal supplied from circulator 146 to bias 150 may be reflected and input back to circulator 146. Therefore, to prevent the output signal of amplifier 144 from being affected, circulator 146 releases the signal returned from bias 150 to terminator 148, as indicated by the dashed arrow, where it is consumed. Terminator 148 is, for example, a 50Ω terminator.

[0064] Bias 150 adds a constant current supplied from current source 152 to a constant frequency signal supplied from circulator 146 and outputs it. Current source 152 functions as a constant current source for supplying the drive current (i.e., bias current) to LD 154. LD 154 is driven by the output signal from bias 150 and outputs laser light. The output signal from bias 150 is superimposed with a constant frequency (i.e., microwave frequency) supplied from circulator 146 on a constant level current, thus the laser light output from LD 154 becomes amplitude-modulated light (i.e., modulated light). That is, LD 154 is controlled by direct modulation to output modulated light. The constant frequency (i.e., microwave frequency) supplied from circulator 146 functions as the modulation signal for the modulated light output from bias 150.

[0065] The modulated light output from LD154 is transmitted to PD158 via optical fiber 156. PD158 performs photoelectric conversion on the modulated light input from optical fiber 156. For PD158 to perform photoelectric conversion, a reverse bias voltage needs to be applied to PD158. The reverse bias voltage is supplied from voltage source 162 and applied to PD158 via biaser 160. Voltage source 162 is a power source that outputs a constant voltage, such as a battery (e.g., a dry cell battery). Preferably, a photoelectric conversion element that converts light into potential is used instead of a battery. The light irradiated onto the photoelectric conversion element can also be natural light, but as described later, light can also be generated by providing a light emitter. More preferably, as described later, it is effective to irradiate the photoelectric conversion element with a portion of the modulated light or excitation light irradiating the diamond, or leakage light of fluorescence emitted from the diamond. In this way, electrical insulation between the diamond and the light source and the microwave source is achieved by utilizing a battery or a mechanism that generates potential through light. Compared to structures that utilize batteries, structures that use light sources become more complex, but the lifespan of the diamond optical-magnetic sensor system 100 is longer.

[0066] PD158 converts the modulated light input from optical fiber 156 into an electrical signal and outputs it to bias 160. The electrical signal output from PD158 is a signal composed of an AC component and a DC component having the same frequency as the modulation frequency (i.e., microwave frequency) of the modulated light. As described above, the electrical signal output from PD158 can be amplified by a power amplifier and input to bias 160, or the electrical signal output from bias 160 can be amplified by power amplification. The power used in the power amplifier is supplied by a battery, for example. Preferably, a photoelectric conversion element that converts light into electricity is used instead of a battery. The light irradiated onto the photoelectric conversion element can be natural light, but a light emitter can also be used to generate light. More preferably, it is effective to irradiate the photoelectric conversion element with a portion of the modulated light or excitation light irradiating the diamond, or leakage light of fluorescence emitted from the diamond. In this way, by utilizing a battery or a mechanism that generates electricity through light, electrical insulation is achieved between the diamond and the light source and the microwave source, enabling the irradiation of the diamond with higher output microwaves and enabling magnetic detection with higher sensitivity. Compared to structures that utilize batteries, structures that use light sources become more complex, but the lifespan of the diamond optical-magnetic sensor system 100 is longer.

[0067] Bias 160 applies a constant voltage (i.e., the reverse bias voltage of PD158) supplied from voltage source 162 to the signal input from PD158 and outputs it. That is, bias 160 removes the DC component from the signal input from PD158 and outputs the AC component.

[0068] The voltage source 162 used to supply the reverse bias voltage to PD158 is not limited to the aforementioned dry cell battery. The reverse bias voltage can also be generated using a photoelectric conversion element. For example, such as... Figure 4 As shown, in Figure 3 Alternatively, solar cell 300 and projector 302 can be used to replace voltage source 162. Additionally, such as... Figure 5 As shown, a photodiode 304 can also be used to replace the voltage source 162. Figure 4 as well as Figure 5 All from Figure 3 The structure shown is extracted from the portion containing the biaser 160.

[0069] Reference Figure 4 The solar cell 300 generates a DC voltage by being illuminated by light output from the transmitter 302. The light output from the transmitter 302 is represented by a dashed line. The generated DC voltage is supplied to the biaser 160 as the reverse bias voltage of the PD158. Thus, the DC component is removed from the signal input from the PD158 to the biaser 160, leaving only the AC component as the output. It should be noted that the light illuminating the solar cell 300 is not limited to the light output from the transmitter 302. Natural light can also be illuminating the solar cell 300. Furthermore, as described later, a portion of the modulated light or excitation light, or leakage light from the fluorescence emitted from the diamond, can also be used to illuminate the solar cell 300.

[0070] Additionally, refer to Figure 5 Photodiode 304 is irradiated as a light source for diamond 104 (reference). Figure 3 A portion of the excitation light irradiated by the photodiode 304 leaks into the excitation light 306, generating a DC voltage. This generated DC voltage is supplied to the biaser 160 as the reverse bias voltage of the PD158. Thus, the DC component is removed from the signal input from the PD158 to the biaser 160, leaving only the AC component as the output. It should be noted that the light irradiated onto the photodiode 304 is not limited to the leakage excitation light 306. Natural light can also be irradiated onto the photodiode 304. Alternatively, light from the optical fiber 156 (see reference 160) can also be used. Figure 3 A portion of the modulated light input to PD158 illuminates photodiode 304. In this case, to maintain a constant output potential of the photodiode, a general electronic circuit design using a Zener diode or similar device is required. Alternatively, a portion of the leakage light from the diamond fluorescence can also illuminate photodiode 304.

[0071] The AC signal (i.e., microwave) output from bias 160 is input to circulator 164. Circulator 164 outputs the signal supplied from bias 160 to resonator 168. A portion of the signal supplied from circulator 164 to resonator 168 may be reflected and input back to circulator 164. Therefore, to avoid affecting the output signal of bias 160, circulator 164 releases the signal returned from resonator 168 to terminator 166 as indicated by the dashed arrow, where it is consumed. Terminator 166 is, for example, a 50Ω terminator.

[0072] The resonator 168 amplifies the supplied microwaves and directs them toward the diamond 104. For example, refer to... Figure 6 The resonator 168 includes an impedance converter 170 and a resonator 172. A diamond 104 is disposed near the resonator 172 (including inside the resonator 172). The impedance converter 170 is, for example, a λ / 4 variable resistor, and the resonator 172 is, for example, a λ / 4 stub. The resonator 172 is, for example, a stub formed by two parallel copper wires of a length equal to one-quarter of the electrical length of a microwave, with the opposite ends of the ends connected to the impedance converter 170 open (i.e., a λ / 4 open-circuit stub). Alternatively, the resonator 172 may also be, for example, a stub formed by two parallel copper foils of a length equal to one-quarter of the electrical length of a microwave, with the opposite ends of the ends connected to the impedance converter 170 connected connected (i.e., a λ / 4 short-circuit stub). Through the impedance converter 170, the impedance of the circulator 164 can be reduced or increased from the perspective of the resonator 172. Resonator 172 functions as a series or parallel resonant circuit, amplifying the supplied microwaves. This allows microwaves that induce magnetic resonance at the NV center of diamond 104 to irradiate diamond 104. Resonator 168 can be a microstrip line resonator or a coplanar waveguide resonator.

[0073] Based on the above, the transmission paths for excitation light, microwaves, and fluorescence transmitted between the diamond photomagnetic sensor (i.e., diamond 104, photoelectric conversion unit 106, and transmission unit 108) and the measuring device (i.e., detection unit 128 and control unit 130, etc.) can all be constructed using optical fibers 114 and 126 (refer to...) as non-metallic components. Figure 1 Therefore, in the measurement of high-voltage electrical equipment, it is easy to ensure insulation isolation to avoid insulation failure, thus improving the freedom and flexibility of the measurement.

[0074] Since it does not use antennas or other means to transmit electromagnetic waves (i.e., microwaves) through space, it is not limited by radio wave methods. Therefore, the measurement environment is not limited to a shielded room, and measurements can be performed in any environment. In addition, the diamond optical-magnetic sensor (i.e., diamond 104, photoelectric conversion unit 106, and transmission unit 108) can be more compact than the wavelength of the electromagnetic waves used in the measurement (e.g., about 10 cm), and can be housed in a spherical or other cornerless housing. Therefore, in the measurement of high-voltage electrical equipment, it is easy to avoid electric field concentration.

[0075] The above description describes a diamond optical-magnetic sensor that includes an NV center and transmits microwaves via optical power, but it is not limited to this. Any sensor that utilizes light whose intensity is modulated to the frequency of an electromagnetic wave region (i.e., modulated light) is acceptable. Transmitting electromagnetic waves via optical power is preferred. Transmitting electromagnetic waves in the microwave frequency band via optical power is more preferred. Transmitting electromagnetic waves with a frequency of 1 GHz to 5 GHz via optical power is even more preferred.

[0076] As described above, microwaves are preferably generated from modulated light via PD158, but this is not a limitation. Any device that performs discharge conversion or a sensor utilizing the element is acceptable.

[0077] The wavelength of the carrier wave of the modulated light is preferably contained in the near-infrared light band. This makes the generation and transmission of the modulated light easier.

[0078] As described above, the modulated light is laser light output from the LD154. This allows for an increase in the intensity of the modulated light and enables it to be transmitted over greater distances.

[0079] As described above, the modulated light is light output from the LD154 by controlling the driving current of the LD154 supplied by the current source 152 to vary at a modulation frequency. Therefore, modulated light can be easily generated by a direct modulation method, enabling miniaturization of the modulation device.

[0080] As described above, the drive current of the LD154 supplied by the current source 152 is controlled by the biaser 150. Therefore, modulated light can be easily generated using the LD154.

[0081] As described above, the excitation light is a laser. Therefore, the excitation light can be easily generated using the excitation light generating unit 120.

[0082] As described above, the modulated light is transmitted via optical fiber 114 and received by irradiation unit 116. This allows for reliable transmission of the modulated light to irradiation unit 116. Furthermore, the diamond optical-magnetic sensor can be safely used in high-voltage electrical equipment.

[0083] As described above, the excitation light is transmitted through the optical fiber 126 and irradiates the diamond 104. This ensures reliable transmission of the excitation light. Furthermore, the diamond optical-magnetic sensor can be safely used in high-voltage electrical equipment.

[0084] As described above, preferably, the transmission unit 108 includes a resonator 168, and the diamond 104 is disposed in the resonator 168. This allows for the efficient irradiation of the diamond with electromagnetic waves (i.e., microwaves).

[0085] Preferably, the diamond 104 is positioned within 10 mm of the PD 158. More preferably, the diamond 104 is positioned within 5 mm of the PD 158. Even more preferably, the diamond 104 is positioned within 3 mm of the PD 158. This allows for the irradiation of the diamond 104 with stronger electromagnetic waves (i.e., microwaves).

[0086] As described above, to avoid electric field concentration, it is preferable to house the diamond 104, the photoelectric conversion unit 106, and the transmission unit 108 within a conductive housing 102. Preferably, the housing 102 includes an opening through which the optical fiber 114 for transmitting modulation light to the photoelectric conversion unit 106 and the optical fiber 126 for transmitting excitation light to the diamond 104 can pass, while the housing 102 is generally sealed. The housing 102 can be formed into a smooth shape without corners, preferably a sphere or ellipsoid. This allows the diamond photomagnetic sensor to be used safely in high-voltage electrical equipment and the like.

[0087] (First variation)

[0088] In the above, modulated light is generated by direct modulation, but it can also be generated by external modulation. Figure 1 The optical power supply unit 118 shown can also be as follows Figure 7 That's how it's structured. The optical power supply unit involved in the first variation generates modulated light through an external modulation method.

[0089] Figure 7 The structure shown is similar to Figure 3 The only difference is the structure of the optical modulation section 112. Figure 7 Other structures and Figure 3 They are the same. Therefore, the following explanation will not repeat the same points, but will focus on the differences. See reference. Figure 7 As described above, the constant-frequency electrical signal output from VCO 140 is transmitted to circulator 146 via attenuator 142 and amplifier 144, and then supplied from circulator 146 to LN element 180. As will be described later, the signal supplied from circulator 146 to LN element 180 is a modulation signal for generating modulated light.

[0090] Current source 152 is a constant current source, supplying drive current (i.e., bias current) to LD154 to drive LD154. LD154 is driven by the output signal from biaser 150, outputting laser light with constant frequency and amplitude. The laser light output from biaser 150 is input to LD154 via optical fiber 182. LN element 180 is an optical modulator formed of lithium niobate (LiNbO3). LN element 180 uses the signal from circulator 146 as a modulation signal to modulate the amplitude of the input laser light and outputs modulated light. That is, LN element 180 generates modulated light through external modulation. As described above, the modulated light output from LN element 180 is transmitted to PD158 via optical fiber 156, where it undergoes photoelectric conversion to become microwaves, which are then irradiated onto diamond 104 via resonator 168.

[0091] By adopting Figure 7 The optical power supply unit shown enables the transmission paths of excitation light, microwaves, and fluorescence transmitted between the diamond optical-magnetic sensor (i.e., diamond 104, photoelectric conversion unit 106, and transmission unit 108) and the measuring device (i.e., detection unit 128 and control unit 130, etc.) to be entirely made of non-metallic components, namely optical fiber 114 and optical fiber 126 (see reference). Figure 1 This structure allows for greater freedom and flexibility in measuring high-voltage electrical equipment by easily ensuring insulation to prevent damage. Since it does not use antennas or similar devices for spatial transmission of electromagnetic waves (i.e., microwaves), it is not limited by radio wave methods. Therefore, the measurement environment is not limited to a shielded room, and measurements can be performed in any environment. Furthermore, the diamond optical-magnetic sensor (i.e., diamond 104, photoelectric conversion unit 106, and transmission unit 108) can be more compact than the wavelength of the electromagnetic waves used in the measurement (e.g., approximately 10 cm), and can be housed in a spherical or other cornerless housing. Therefore, electric field concentration is easily avoided in the measurement of high-voltage electrical equipment.

[0092] By using the LN element 180 and generating modulated light using an external modulation method, high-speed modulation can be performed, and modulated light with a high modulation frequency (e.g., tens of GHz) can be generated.

[0093] (Second variation)

[0094] In the above, such as Figure 2 As shown, the case in which the modulation light and excitation light for optical power supply are transmitted to the vicinity of the diamond 104 via different optical fibers (i.e., fiber 114 and fiber 126) has been described, but it is not limited to this. In the diamond photomagnetic sensor system according to the second variation, the modulation light and excitation light for optical power supply are transmitted via the same optical fiber.

[0095] Reference Figure 8From the light modulation unit 112 (reference) Figure 1 Both the modulated light output from the modulation light generator 120 and the excitation light output from the excitation light generator 120 are transmitted through the optical fiber 190. The carrier frequency of the modulation light is different from the frequency of the excitation light. The modulation light output from the output end of the optical fiber 190 is input to the photoelectric conversion unit 106, where it is photoelectrically converted to generate microwaves as described above. The generated microwaves irradiate the diamond 104. On the other hand, the excitation light output from the output end of the optical fiber 190 directly irradiates the diamond 104. It should be noted that the fluorescence emitted from the diamond 104 can be transmitted to the detection unit 128 through other optical fibers or through the wavelength divider 192. In this way, the wavelength of the carrier light of the modulation light is different from that of the excitation light, thereby allowing the modulation light and excitation light to be easily transmitted using the same optical fiber, reducing the number of components.

[0096] It should be noted that, in order to input the modulation light and excitation light into the optical fiber 190, the optical elements can be arranged such that the optical paths of the modulation light and excitation light overlap at the input end of the optical fiber 190. For example, if the carrier frequencies of the modulation light and the excitation light are different (i.e., different wavelengths), a dichroic mirror can be used. For example, the modulation light can be allowed to pass through the dichroic mirror and enter the optical fiber 190, and the excitation light can be reflected by the dichroic mirror and enter the optical fiber 190.

[0097] (Third variation)

[0098] In the above, such as Figure 8 As shown, the case in which modulated light and excitation light of different frequencies (i.e., different wavelengths) are transmitted to the vicinity of diamond 104 through the same optical fiber 190 has been described, but it is not limited to this. In the diamond photomagnetic sensor system according to the third modified example, modulated light and excitation light of the same frequency (i.e., the same wavelength) are transmitted through the same optical fiber.

[0099] Reference Figure 9 The modulated excitation light is transmitted through optical fiber 190. The modulated excitation light is generated by amplitude modulation of the excitation light at the NV center using a microwave frequency signal as the modulation signal. The carrier frequency of the modulated excitation light is the same as the frequency of the excitation light. The modulated excitation light output from the output end of optical fiber 190 is split into two optical paths by distributor 194. The light from the first optical path is input to photoelectric conversion unit 106, where it is photoelectrically converted to generate microwaves as described above. The generated microwaves irradiate diamond 104. Meanwhile, the light from the second optical path directly irradiates diamond 104 as excitation light.

[0100] like Figure 7 As shown, by using the LN element 180, light can be generated from the excitation light generation section 120 (see reference 120). Figure 1The excitation light output is externally modulated to generate modulated excitation light incident on fiber 190. By modulating the excitation light, it is not necessary to set up an LD (Dielectric-Local Array) for generating the modulated light. Figure 3 as well as Figure 7 The LD154 shown can reduce the number of parts, making manufacturing easier.

[0101] (Fourth variation)

[0102] In the above description, the case of generating microwaves by photoelectric conversion of modulated light through photoelectric conversion unit 106 has been explained, but it is not limited to this. In the diamond photomagnetic sensor system according to the fourth modified example, the modulated light is directly irradiated onto the diamond 104.

[0103] Reference Figure 10 ,and Figure 9 Similarly, modulated excitation light is transmitted via optical fiber 190. The modulated excitation light is generated by amplitude modulation of the excitation light at the NV center using a microwave frequency signal as the modulation signal. The modulated excitation light output from the output end of optical fiber 190 directly irradiates the diamond 104. That is, the modulated excitation light is used as both the excitation light for the NV center and the microwave for magnetic resonance. Therefore, a photoelectric conversion unit 106 for photoelectric conversion is unnecessary, reducing the number of components and simplifying manufacturing.

[0104] The above description focuses on diamond optical-magnetic sensors containing NV centers, but is not limited to this. Any diamond optical-magnetic sensor with a color center possessing electron spin is acceptable. A color center with electron spin is a center that forms a spin triplet state and emits light when excited; the NV center is a representative example. Furthermore, color centers with electron spin are known to exist in silicon-hole centers (i.e., Si-V centers), germanium-hole centers (i.e., Ge-V centers), and tin-hole centers (i.e., Sn-V centers). Therefore, diamonds containing these types of centers can be used instead of diamonds containing NV centers to construct diamond optical-magnetic sensors.

[0105] The above describes the transmission of modulated light to the vicinity of diamond via optical fiber, but it is not a limitation. Lenses and mirrors can also be used instead of optical fibers to transmit modulated light spatially.

[0106] Example 1

[0107] The following examples illustrate the effectiveness of this disclosure. Figure 11 The apparatus used to measure the results is described above. It involves irradiating a diamond with an NV center using microwaves and excitation light, and measuring the fluorescence intensity emitted from the NV center. (Reference) Figure 11 The diamond optical-magnetic sensor 216 in the measuring device is composed of Figure 3The structure shown comprises a diamond 104, a photoelectric conversion unit 106, and a transmission unit 108. However, in Figure 11 middle, Figure 3 Diamond 104 is replaced by diamond 210. A microwave supply source 220 (i.e., a microwave system) is used to irradiate the diamond 210 with microwaves. Figure 3 The modulation signal generation unit 110, optical modulation unit 112, and optical fiber 156 shown transmit the modulated light to the diamond optical-magnetic sensor 216. The structure (i.e., the illumination system) for irradiating the diamond 210 contained in the diamond optical-magnetic sensor 216 with excitation light includes a light source 200, a collimating lens 202, a dichroic mirror 204, a spherical lens 206, and an optical fiber 208. The structure (i.e., the observation system) for observing the fluorescence emitted from the diamond 210 includes the optical fiber 208, the spherical lens 206, the dichroic mirror 204, an LPF (Long Pass Filter) 212, and a photodetector 214.

[0108] Reference Figure 3 A predetermined frequency electrical signal of 3dBm is output from VCO140. The predetermined frequency varies in the range of 2.7GHz to 2.94GHz. The output signal of VCO140 is attenuated by -20dB by attenuator 142, amplified by +40dB by amplifier 144, and input to circulator 146. LD154 uses an LPSC-1550-FC manufactured by Thorlabs. A bias current of 130mA is output from current source 152 and supplied to LD154 via biaser 150 to generate modulated light using direct modulation. The modulated light, containing a DC component of 15mW and an AC component of 10mWrms (effective value), is transmitted to diamond photomagnetic sensor 216 through optical fiber 156. PD158, which constitutes diamond photomagnetic sensor 216, uses an FGA01FC manufactured by Thorlabs. Voltage source 162 uses a dry cell battery. A 9V reverse bias voltage is output from voltage source 162 and supplied to PD158 via biaser 160, generating a microwave electrical signal through photoelectric conversion. The generated microwave is transmitted to resonator 168 via circulator 164 with a characteristic impedance of 50Ω. Resonator 168 uses a λ / 4 variable resistor and a λ / 4 open-circuit stub resonator.

[0109] Alternatively, as a comparative example, instead of microwave supply source 220, a coaxial cable with a characteristic impedance of 50Ω is used to transmit microwaves generated by a microwave generating device (not shown), which then irradiate the diamond 210 via the resonator of the aforementioned coplanar waveguide. The frequency of the microwaves transmitted via the coaxial cable also varies in the range of 2.74GHz to 2.94GHz.

[0110] The excitation light source 200 uses an LD (laser diode) element (specifically, an L515A1 manufactured by Thorlabs) to generate a 5mW green laser (i.e., excitation light). The excitation light output from the source 200 is focused by a collimating lens 202 and then incident on a dichroic mirror 204. The collimating lens 202 is an LA1116-A manufactured by Thorlabs, and the dichroic mirror 204 is an SO6-RG manufactured by Suruga Seiki Co., Ltd. The excitation light (i.e., green light) incident on the dichroic mirror 204 is reflected by the mirror. The reflected light is focused by a spherical lens 206 and directed into an optical fiber 208 (specifically, the fiber core). After propagation in the optical fiber 208, it illuminates the diamond 210. The spherical lens 206 is an MS-08-4.35P1 (8mm in diameter) manufactured by Opto Sigma. Fiber 208 uses a digital optical cable with a core diameter of φ0.9mm.

[0111] The fluorescence emitted from diamond 210, which is incident on optical fiber 208, propagates within fiber 208, is then shaped into parallel light by spherical lens 206, and incident on dichroic mirror 204. The fluorescence (i.e., red light) incident on dichroic mirror 204 passes through dichroic mirror 204 and enters LPF 212. The fluorescence after passing through LPF 212 is detected by photodetector 214. LPF 212 allows light with wavelengths above a predetermined wavelength to pass through, while blocking (e.g., reflecting) light with wavelengths lower than the predetermined wavelength. LPF 212 uses LOPF-25C-593 manufactured by Opto Sigma. Photodetector 214 uses a photodiode (specifically, S6967 manufactured by Hamamatsu Photonics Co., Ltd.). The emitted light from diamond is red light, which passes through LPF 212, but the wavelength of the excitation light is shorter than the wavelength of the emitted light from diamond, and therefore does not pass through LPF 212. This prevents the excitation light emitted from the light source 200 from being detected by the photodetector 214 and thus becoming noise, thereby reducing the detection sensitivity.

[0112] As for diamond 210, type Ib diamond was used, with an electron beam acceleration energy of 3 MeV and an electron beam dose of 3 × 10⁻⁶. 18 pcs / cm 2 Electrons are injected into it, and then it is annealed at 800°C for about 1 hour to produce diamond containing NV centers. Figure 12 As shown, it is cut into a pyramidal prism with a bevel of 1mm to produce diamond 210. Figure 12The diamond shown is a triangular pyramid with vertices A, B, C, and D, and angles α, β, and γ all being right angles. Excitation light (i.e., green light) is incident perpendicularly into the plane of triangle ABC through the aforementioned optical fiber 208. Since the refractive index of diamond is approximately 2.5, the excitation light incident into the diamond is reflected by the three planes (i.e., triangles ABD, BCD, and ACD) that function as reflective surfaces, and illuminates the center of NV through a longer optical path than in the case of no reflection. The fluorescence (i.e., red light) emitted from the center of NV is reflected by the aforementioned three planes that function as reflective surfaces, exits from the plane of triangle ABC where the excitation light was incident, and enters the aforementioned optical fiber 208.

[0113] As described above, the fluorescence emitted from diamond 210 when it is irradiated with microwaves using microwave power supply 220 for optical power supply is measured, and the results are shown below. Figure 13 .exist Figure 13 In the diagram, the horizontal axis represents the frequency of the microwaves irradiating the diamond 210 (i.e., the frequency of VCO140), and the vertical axis represents the fluorescence intensity measured by the photodetector 214. By keeping the microwave power constant and varying the microwave frequency, the valley of the intensity (i.e., red luminance) of the red fluorescence emitted from the NV center of the diamond can be observed. From this, the spin detection contrast ratio (i.e., the rate of decrease in red luminance) can be calculated. Figure 14 The value obtained by dividing the valley size S in the graph shown by the fluorescence intensity S0. As a theoretical formula for the sensitivity δB (i.e., the resolution of the detected magnetic field B) of the diamond photomagnetic sensor, the following Equation 1 is known, and the spin detection contrast ratio affects the sensitivity δB.

[0114] [Number 1]

[0115]

[0116] In Equation 1, γ is the gyrometry ratio (i.e., a constant), which is close to the gyrometry ratio of the electron (i.e., 1.76 × 10⁻⁶). 11 The values ​​of rad / s / T are given. η is the fluorescence detection efficiency, and C is the spin detection contrast ratio. N is the number of negatively charged NV centers in the region where the fluorescence is focused by the excitation light. T2 is the transverse relaxation time of the electron spin. According to the theoretical formula for the sensitivity (Equation 1), the higher the spin detection contrast ratio, the smaller the sensitivity δB, and the higher the sensitivity.

[0117] Depend on Figure 13 The measurement results show that a fluorescence intensity of 1 μA and a spin detection contrast ratio of approximately 1.3% were obtained. Since the microwave supply source 220 includes circulators 146 and 164, therefore... Figure 13In the measurement results shown, the baseline variation in fluorescence intensity was suppressed to approximately ±0.1%.

[0118] As a comparative example, the fluorescence emitted from diamond 210 after microwaves were transmitted through a coaxial cable and irradiated thereon was measured, and the results are shown below. Figure 15 .exist Figure 15 In the diagram, the horizontal axis represents the frequency of the microwaves irradiating the diamond 210, and the vertical axis represents the fluorescence intensity measured by the photodetector 214. By keeping the microwave power constant and varying the microwave frequency, the valley of the intensity (i.e., red luminance) of the red fluorescence emitted from the NV center of the diamond was observed, yielding a fluorescence intensity of 1 μA and a spin detection contrast ratio of approximately 2%. Since the microwaves are transmitted via a coaxial cable, a circulator is not included, thus... Figure 15 In the measurement results shown, the baseline variation of fluorescence intensity was approximately ±1%.

[0119] If Figure 13 and Figure 15 Comparing the measurement results shown, by using optical power to transmit microwaves, the same fluorescence intensity could be observed as when using coaxial cable to transmit microwaves, and the same level of spin detection contrast ratio could also be achieved. Therefore, in magnetic detection using a diamond NV center, the optical power supply of microwaves is effective, demonstrating the effectiveness of the diamond optical-magnetic sensor with the corresponding structure.

[0120] Example 2

[0121] Similar to Example 1, using Figure 11 The measuring apparatus shown uses a microwave supply source 220 different from that in Example 1 to irradiate the diamond 210 with the NV center with microwaves and excitation light, and measures the fluorescence intensity emitted from the NV center. Specifically, the microwave supply source 220 is as follows: Figure 7 The structure shown is configured to use an LN element to input an external electrical modulation signal to generate modulated light through an external modulation method. The other parts are configured as the same experimental structure as in Example 1. With this structure, modulated light can be generated using an LN element. The modulated light, after passing through an optical fiber, is converted into microwaves by a PD and a bias voltage converter and then irradiates the diamond. By changing the frequency of the microwaves, a modulation scheme similar to... Figure 13 Similarly, the fluorescence intensity decreases at the resonant frequency in the spectrum. It can be confirmed that the frequency location of the troughs in the spectrum shifts depending on the strength of the magnetic field, thus enabling the detection of the magnetic field.

[0122] Example 3

[0123] Similar to Example 1, using Figure 11The measuring apparatus shown modifies the fiber-optic optical transmission component in the microwave supply source 220, irradiates the diamond 210 with the NV center with microwaves and excitation light, and measures the fluorescence intensity emitted from the NV center. Specifically, as... Figure 8 As shown, the modulated light and excitation light are combined and transmitted into the same optical fiber. At the output side, the light is split again by a distributor. The split modulated light is then used in the photoelectric conversion unit to generate microwaves via a PD and a bias circuit, which can then irradiate the diamond. By controlling the frequency of the modulated light, the frequency of the microwaves can be varied to obtain a signal similar to that of the diamond. Figure 13 Similarly, the fluorescence intensity decreases at the resonant frequency in the spectrum. It can be confirmed that the frequency location of the troughs in the spectrum shifts depending on the strength of the magnetic field, thus enabling the detection of the magnetic field.

[0124] Example 4

[0125] Similar to Example 1, using Figure 11 The measuring apparatus shown modifies the structure of the microwave supply source 220, irradiates the diamond 210 with the NV center with microwaves and excitation light, and measures the fluorescence intensity emitted from the NV center. Specifically, in the photoelectric conversion unit (and... Figure 3 In the photoelectric conversion unit 106 (corresponding to), in the PD (and Figure 3 The power amplifier (amplifier) ​​following the PD158 (corresponding to the PD158) converts the modulated light into an electrical signal and amplifies the power. Then, it passes through a bias amplifier (and...) Figure 3 The bias unit 160 (corresponding to the bias unit 160) separates the high-frequency component and the DC component. The high-frequency component illuminates the diamond 210. The power amplifier uses the DC component separated by the bias unit. By changing the frequency of the modulated light, the frequency of the microwave can be changed, thus obtaining a signal similar to the DC component separated by the bias unit. Figure 13 Similarly, the fluorescence intensity decreases at the resonant frequency in the spectrum. It can be confirmed that the frequency location of the troughs in the spectrum shifts depending on the strength of the magnetic field, thus enabling the detection of the magnetic field.

[0126] Example 5

[0127] Similar to Example 1, using Figure 11 The measuring apparatus shown uses a 5V rated output 2W solar cell instead of a 9V dry cell battery (refer to the voltage source 162) for the voltage source 162. Figure 4 The fluorescence intensity emitted from the NV center was measured by irradiating a diamond-210 solar cell with an NV center using microwaves and excitation light. A projector was used to irradiate the solar cell. By changing the frequency of the modulated light, the frequency of the microwaves was varied, allowing for the measurement of the fluorescence intensity. Figure 13 Similarly, the fluorescence intensity decreases at the resonant frequency in the spectrum. It can be confirmed that the frequency location of the troughs in the spectrum shifts depending on the strength of the magnetic field, thus enabling the detection of the magnetic field.

[0128] The present disclosure has been described above by way of example, but the above-described embodiments are merely examples and the present disclosure is not limited to the above-described embodiments. The scope of the present disclosure is as set forth in the claims, based on the detailed description of the invention, and includes all modifications within the meaning and scope of the statements herein.

[0129] Explanation of reference numerals in the attached figures

[0130] 100: Diamond optical-magnetic sensor system;

[0131] 102: Shell;

[0132] 104, 210: Diamond;

[0133] 106: Photoelectric conversion unit;

[0134] 108: Transmission Department;

[0135] 110: Modulation signal generation unit;

[0136] 112: Optical modulation section;

[0137] 114, 126, 156, 182, 190, 208: Fiber optic cables;

[0138] 116: Irradiation Department;

[0139] 118: Optical Power Supply Department;

[0140] 120: Excitation light generation section;

[0141] 122, 192: Wavelength dividers;

[0142] 124: Focusing section;

[0143] 128: Testing Department;

[0144] 130: Control Department;

[0145] 140: VCO;

[0146] 142: Attenuator;

[0147] 144: Amplifier;

[0148] 146, 164: Circulator;

[0149] 148, 166: Terminal;

[0150] 150, 160: Bias setter;

[0151] 152: Current source;

[0152] 154:LD;

[0153] 158: PD;

[0154] 162: Voltage source;

[0155] 168: Resonator;

[0156] 170: Impedance converter;

[0157] 172: Resonator;

[0158] 180: LN element;

[0159] 194: Distributor;

[0160] 200: Light source;

[0161] 202: Collimating lens;

[0162] 204: Dichroic mirror;

[0163] 206: Spherical lens;

[0164] 212: LPF;

[0165] 214: Photodetector;

[0166] 216: Diamond optical-magnetic sensor;

[0167] 220: Microwave power supply;

[0168] 300: Solar cell;

[0169] 302: light projector;

[0170] 304: Photodiode;

[0171] 306: Leakage excitation light;

[0172] A, B, C, D: Points;

[0173] α, β, γ: angles.

Claims

1. A diamond optical-magnetic sensor, wherein, The diamond optical-magnetic sensor includes: Diamond, which has color centers with electron spin and is excited by light when irradiated; and The irradiation section irradiates the diamond with electromagnetic waves for magnetic resonance. The irradiation unit receives the modulated light after amplitude modulation. The modulation frequency of the modulated light is contained within the microwave frequency band. The irradiation unit further includes a photoelectric conversion unit that converts the modulated light into an electrical signal. The electromagnetic waves used in magnetic resonance are formed by the electrical signals generated by the photoelectric conversion unit. The photoelectric conversion unit includes a photodiode that converts the modulated light into the electrical signal. The irradiation unit further includes a first biasing device that extracts the AC component from the electrical signal generated by the photodiode. The electromagnetic waves used in magnetic resonance are formed by the alternating current component. The photoelectric conversion unit includes a photoelectric conversion element that converts a portion of the light including at least one of the light from the projector, the modulated light, and the excitation light into an electrical potential. The first bias device extracts the AC component from the electrical signal by applying the potential generated by the photoelectric conversion element and adding the potential as the reverse bias voltage of the photodiode to the electrical signal generated by the photodiode.

2. The diamond optical-magnetic sensor according to claim 1, wherein, The photoelectric conversion unit further includes an amplifier that amplifies the output signal of the photodiode or the first bias device. The output signal is amplified by applying the power generated by the photoelectric conversion element to the amplifier.

3. The diamond optical-magnetic sensor according to claim 1 or 2, wherein, The carrier wave of the modulated light has a wavelength different from that of the excitation light.

4. The diamond optical-magnetic sensor according to claim 1 or 2, wherein, The wavelength of the carrier wave of the modulated light is contained in the near-infrared light band.

5. The diamond optical-magnetic sensor according to claim 1 or 2, wherein, The excitation light has the same wavelength as the carrier wavelength of the modulation light. The modulated light is generated by amplitude modulation of the excitation light.

6. The diamond optical-magnetic sensor according to claim 1 or 2, wherein, The modulated light is a laser.

7. The diamond optical-magnetic sensor according to claim 1 or 2, wherein, The modulated light is output from the laser diode by controlling the drive current of the laser diode to vary at the modulation frequency.

8. The diamond optical-magnetic sensor according to claim 1 or 2, wherein, The modulated light is output from the LN element by controlling the LN element through the modulation signal of the modulation frequency.

9. The diamond optical-magnetic sensor according to claim 7, wherein, The driving current of the laser diode is controlled by a second biaser.

10. The diamond optical-magnetic sensor according to claim 1 or 2, wherein, The excitation light is a laser.

11. The diamond optical-magnetic sensor according to claim 1 or 2, wherein, The modulated light is transmitted via the first optical fiber and received by the irradiation unit.

12. The diamond optical-magnetic sensor according to claim 11, wherein, The excitation light is transmitted through a second optical fiber and irradiates the diamond.

13. The diamond optical-magnetic sensor according to claim 11, wherein, The excitation light is transmitted via the first optical fiber and irradiates the diamond.

14. The diamond optical-magnetic sensor according to claim 1 or 2, wherein, The irradiation unit includes a resonator. The diamond is disposed in the resonator.

15. The diamond optical-magnetic sensor according to claim 1 or 2, wherein, The diamond is positioned within 5 mm of the photoelectric conversion unit.

16. The diamond optical-magnetic sensor according to claim 1 or 2, wherein, The irradiation unit irradiates the diamond with the input modulated light as electromagnetic waves for magnetic resonance.

17. The diamond optical-magnetic sensor according to claim 1 or 2, wherein, The diamond optical-magnetic sensor also includes a housing portion formed into a smooth shape by means of conductive components. The diamond and the irradiation unit are housed in the housing.

18. A diamond optical-magnetic sensor system, wherein, The diamond optical-magnetic sensor system includes: The diamond optical-magnetic sensor according to any one of claims 1 to 17; The optical modulation unit that generates the modulated light; and The transmission unit that transmits the modulated light, The modulated light is transmitted via the transmission unit and received by the irradiation unit.

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