Diamond optomagnetic sensor

Abstract

A diamond optical magnetic sensor (100) of the present invention includes a diamond (102) having a color center with an electron spin, a transmission circuit (106) that transmits an electromagnetic wave, and an irradiation section that irradiates the electromagnetic wave transmitted by the transmission circuit (106) to the diamond (102), the transmission circuit (106) including an impedance converter (108) for making the impedance of an electromagnetic wave source (110) that outputs the electromagnetic wave low or high when viewed from the irradiation section, the irradiation section including a resonator (104).

Description

Technical Field

[0001] This disclosure relates to diamond optical-magnetic sensors. This application claims priority based on Japanese Application No. 2021-059796, 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 hole 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 comprises: 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; a transmission circuit for transmitting electromagnetic waves; and an irradiation unit for irradiating the diamond with the electromagnetic waves transmitted by the transmission circuit, the transmission circuit including an impedance converter for making the impedance of the electromagnetic wave source of the output electromagnetic waves lower or higher when observed from the irradiation unit.

[0009] Another aspect of this disclosure relates to a diamond photomagnetic sensor comprising: a diamond having a color center with electron spin; a transmission circuit for transmitting electromagnetic waves; and an irradiation unit for irradiating the diamond with the electromagnetic waves transmitted by the transmission circuit, the irradiation unit comprising a resonator. Attached Figure Description

[0010] Figure 1 This is a circuit diagram illustrating the diamond optical-magnetic sensor according to the first embodiment of this disclosure.

[0011] Figure 2 This is a circuit diagram illustrating the diamond optical-magnetic sensor according to the second embodiment of this disclosure.

[0012] Figure 3 It means Figure 2 The three views (i.e., top view, side view and bottom view) of a specific example of a diamond optical-magnetic sensor shown.

[0013] Figure 4 These are two views (i.e., the top view and the front view) showing the state of a diamond array in a coplanar waveguide.

[0014] Figure 5 It means in Figure 3 The diagram shows a cross-sectional view of the magnetic field formed on the diamond by microwave irradiation in the diamond optical-magnetic sensor.

[0015] Figure 6 This is a circuit diagram illustrating the diamond optical-magnetic sensor according to the third embodiment of this disclosure.

[0016] Figure 7 This is a circuit diagram illustrating the diamond optical-magnetic sensor according to the fourth embodiment of this disclosure.

[0017] Figure 8 It means Figure 7 The three views (i.e., top view, side view and bottom view) of a specific example of a diamond optical-magnetic sensor shown.

[0018] Figure 9 It means in Figure 8 The diagram shows a cross-sectional view of the magnetic field formed on the diamond by microwave irradiation in the diamond optical-magnetic sensor.

[0019] Figure 10 These are three views (i.e., top view, side view, and bottom view) showing a specific example of the diamond optical-magnetic sensor according to the fifth embodiment of this disclosure.

[0020] Figure 11 It means in Figure 10The diagram shows a cross-sectional view of the magnetic field formed on the diamond by microwave irradiation in the diamond optical-magnetic sensor.

[0021] Figure 12 This is a three-view diagram (i.e., top view, side view, and bottom view) of a diamond optical-magnetic sensor that is powered by microwave through wireless transmission.

[0022] Figure 13 These are the three views (i.e., the top view, side view, and bottom view) of the diamond optical-magnetic sensor involved in the first modified example.

[0023] Figure 14 These are the three views (i.e., the top view, side view, and bottom view) of the diamond optical-magnetic sensor involved in the second variation.

[0024] Figure 15 This is a schematic diagram representing a multi-level λ / 4 variable.

[0025] Figure 16 This is a schematic diagram representing a cone-shaped λ / 4 variable.

[0026] Figure 17 This is a schematic diagram showing the structure of the measuring device used in the experiment.

[0027] Figure 18 This is a top view showing the microstrip resonator used in the experiment.

[0028] Figure 19 This is a top view showing the resonator of the coplanar waveguide used in the experiment.

[0029] Figure 20 This is a graph showing the change in the intensity of fluorescence emitted from the NV center of a diamond.

[0030] Figure 21 It is a graph representing the experimental results. Detailed Implementation

[0031] [The problem this disclosure aims to solve]

[0032] Following Non-Patent Document 1, when using a coplanar waveguide to transmit microwaves from a power source and irradiate the center of the NV for magnetic resonance, a power supply of approximately 30 dBm (=1 W) is required to achieve sufficient magnetic resonance. Furthermore, when using a microstrip line, a similar level of microwave power is also required.

[0033] The microwaves used to induce magnetic resonance at the NV center have a frequency of approximately 3 GHz, which varies due to the influence of magnetic fields, electric fields, and temperature. The coefficients below represent the extent of these influences (i.e., the variation in the resonant frequency).

[0034] Influence of magnetic fields: 28GHz / T

[0035] The effect of the electric field: 17Hz / (V / cm)

[0036] Temperature effect: -74.2kHz / K

[0037] Therefore, if the power of the microwaves used for magnetic resonance at the NV center is too high, a temperature rise will occur around the diamond containing the NV center due to microwave transmission losses, affecting the frequency of the magnetic resonance and thus impacting the measurement. Therefore, it is desirable to perform magnetic resonance with the lowest possible microwave power.

[0038] Furthermore, when using diamond photomagnetic sensors in measurements within high-voltage electrical equipment, it is desirable to transmit excitation light, fluorescence, and microwaves with secure remote insulation to avoid insulation damage from high voltage. Using optical fibers allows for the transmission of excitation light and fluorescence with secure remote insulation. Regarding microwave transmission, securing insulation is difficult in coaxial cable-based transmission, but it is possible to secure insulation remotely by using transmitting and receiving antennas for spatial transmission via radio waves. When using transmitting and receiving antennas for spatial microwave transmission, it is preferable to achieve this in a power-saving, compact, and low-cost manner. That is, it is desirable to suppress microwave transmission power, increase antenna gain, and achieve magnetic resonance with microwaves using the least possible power.

[0039] Therefore, the purpose of this disclosure is to provide a diamond optical-magnetic sensor that can operate using microwaves with low power.

[0040] [The Effects of This Disclosure]

[0041] According to this disclosure, a diamond optical-magnetic sensor capable of operating via microwaves with low power can be provided.

[0042] [Description of embodiments of this disclosure]

[0043] The embodiments described herein are presented in an explanatory manner. At least some of the embodiments described below may be combined arbitrarily.

[0044] (1) The diamond photomagnetic sensor according to the first aspect of this disclosure comprises: a diamond having a color center with electron spin; a transmission circuit for transmitting electromagnetic waves; and an irradiation unit for irradiating the diamond with the electromagnetic waves transmitted by the transmission circuit, the transmission circuit including an impedance converter for making the impedance of the electromagnetic wave source of the output electromagnetic wave lower or higher when observed from the irradiation unit. Thus, the diamond photomagnetic sensor can operate using microwaves with low power.

[0045] (2) The diamond photomagnetic sensor according to the second aspect of this disclosure comprises: a diamond having a color center with electron spin; a transmission circuit for transmitting electromagnetic waves; and an irradiation unit for irradiating the diamond with the electromagnetic waves transmitted by the transmission circuit, the irradiation unit comprising a resonator. Thus, the diamond photomagnetic sensor can operate using microwaves with low power.

[0046] (3) Alternatively, in the diamond photomagnetic sensor involved in the second aspect, the transmission circuit includes an impedance converter that is used to lower or raise the impedance of the electromagnetic wave source of the output electromagnetic wave when observed from the irradiation section. This allows for an increase in the current flowing through the resonator or the voltage applied to the resonator, enabling the electromagnetic wave to be efficiently irradiated onto the diamond.

[0047] (4) Alternatively, the impedance converter may include a transformer. This allows for the easy fabrication of a diamond optical-magnetic sensor.

[0048] (5) Alternatively, the impedance converter may include a λ / 4 variable. This allows for high-precision impedance conversion between the electromagnetic wave transmission circuit and the resonator, enabling the electromagnetic waves to be efficiently irradiated onto the diamond.

[0049] (6) Alternatively, the resonator may contain a λ / 4 stub. This allows for high-precision adjustment of the resonator's resonant frequency and efficient irradiation of the diamond with electromagnetic waves.

[0050] (7) Alternatively, the λ / 4 stub may contain a λ / 4 open-circuit stub. This simplifies the design of diamond shapes that achieve high fluorescence focusing efficiency. Furthermore, series resonance can be achieved, increasing the short-circuit current and enabling the irradiation of microwaves with stronger magnetic fields.

[0051] (8) Alternatively, the λ / 4 stub may contain a λ / 4 short-circuit stub. This enables parallel resonance, increases the open-circuit voltage, and allows for the irradiation of microwaves with a stronger magnetic field.

[0052] (9) Alternatively, the λ / 4 stub may contain two parallel linear conductors. This increases the magnetic field applied to the diamond by microwaves.

[0053] (10) Alternatively, the λ / 4 stub may contain four parallel linear conductors. This increases the magnetic field applied to the diamond by microwaves.

[0054] (11) Alternatively, the λ / 4 stub may contain two flat conductors, or the two flat conductors may be arranged parallel to each other. This increases the magnetic field applied to the diamond by microwaves and improves the uniformity of the magnetic field.

[0055] (12) Alternatively, the thickness of the diamond may be greater than 0 and less than 0.3 mm, or two linear conductors may be configured to sandwich the diamond while being separated in the thickness direction of the diamond. This increases the magnetic field applied to the diamond by microwaves.

[0056] (13) Alternatively, the thickness of the diamond may be 0.5 mm or more and 3 mm or less, or two flat conductive plates may be configured to sandwich the diamond and be separated in the thickness direction of the diamond. This can increase the magnetic field applied to the diamond by microwaves and improve the uniformity of the magnetic field.

[0057] (14) Alternatively, the λ / 4 variable resistor can be formed as a cone with a continuously varying width. This allows for easy and high-precision wideband impedance conversion.

[0058] (15) Alternatively, the λ / 4 variable can be formed as a multi-stage type with discretely varying widths. This allows for easy and high-precision wideband impedance conversion.

[0059] (16) Alternatively, the impedance converter may include a microstrip line, or the width of the microstrip line may be less than 1 / 2 of its length. Thus, impedance can be easily and accurately converted with less loss.

[0060] (17) Alternatively, the width of the λ / 4 stub may be less than half the length of the λ / 4 stub. Thus, resonance can be achieved with less radiation.

[0061] (18) Alternatively, the center of the diamond may be located within a predetermined range from the connection point of the λ / 4 open-circuit stub to the transmission circuit; the predetermined range may be more than 1 / 8 and less than 3 / 8 of the electrical length of the λ / 4 open-circuit stub; or the length of the diamond along the long side of the λ / 4 open-circuit stub may be less than 1 / 4 of the electrical length. This increases the magnetic field applied to the diamond by microwaves.

[0062] (19) Alternatively, the center of the diamond may be located within a predetermined range from the short-circuit end of the λ / 4 short-circuit stub, or the predetermined range may be more than 1 / 8 and less than 3 / 8 of the electrical length of the λ / 4 short-circuit stub, and the length of the diamond along the long side of the λ / 4 short-circuit stub may be less than 1 / 4 of the electrical length. This increases the magnetic field applied to the diamond by microwaves.

[0063] [Details of the embodiments disclosed herein]

[0064] 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.

[0065] (First Implementation)

[0066] Reference Figure 1 The diamond optical-magnetic sensor 100 according to the first embodiment of this disclosure includes a diamond 102, a resonator 104, a transmission circuit 106, and a microwave source 110. This embodiment efficiently supplies microwaves to the diamond 102 through a resonator composed of a lumped constant circuit. The diamond 102 includes an NV center.

[0067] The resonator 104 includes a coil L1 and a capacitor C1, forming a series resonant circuit. The diamond 102 is disposed near the coil L1 (including the interior of the coil L1). Furthermore, the interior of the coil L1 refers to the space surrounded by the windings constituting the coil L1. The resonator 104 is an irradiation section for irradiating microwaves onto the diamond 102. The transmission circuit 106 includes an impedance converter 108 and a coaxial cable with a characteristic impedance Z1 connecting the impedance converter 108 to the microwave source 110. The microwave source 110 is a power source that generates microwaves at a predetermined frequency. The characteristic impedance Z1 is, for example, 50Ω. The microwave source 110 supplies electromagnetic waves (i.e., microwaves) to the diamond photomagnetic sensor 100 via the coaxial cable (i.e., 50Ω power supply). The impedance converter 108 is specifically a transformer. By using a transformer in the impedance converter 108, a diamond photomagnetic sensor can be easily formed. With this configuration, the resonator 104 and the impedance converter 108 function as resonators, enabling the magnetic field of the microwaves from the microwave source 110 to be amplified and irradiated onto the diamond 102.

[0068] For example, if the turns ratio of the impedance converter 108 winding is set to primary side:secondary side = 1:N (where N is a positive rational number) for impedance conversion, the open-circuit voltage on the load side (i.e., the LC series resonator) becomes N times, and the impedance becomes N. 2 The short-circuit current flowing through the series resonant circuit becomes 1 / N times. Therefore, even if the power of the microwaves output from the microwave source 110 is smaller than before, as long as N is smaller than 1, the diamond optical-magnetic sensor 100 can function as a magnetic sensor.

[0069] (Second Implementation)

[0070] Reference Figure 2 The diamond optical-magnetic sensor 120 according to the second embodiment of this disclosure includes a diamond 102, a resonator 124, a transmission circuit 126, and a microwave source 110. This embodiment efficiently supplies microwaves to the diamond 102 through a resonator composed of high-frequency circuitry.

[0071] The resonator 124 includes a λ / 4 stub 122 and functions as a series resonant circuit. The diamond 102 is positioned near the λ / 4 stub 122. The resonator 124 is the irradiation unit for irradiating the diamond 102 with microwaves. The transmission circuit 126 includes a λ / 4 variable 128 and a coaxial cable with a characteristic impedance Z1 connecting the λ / 4 variable 128 to the microwave source 110. The characteristic impedance Z1 is, for example, 50Ω. The microwave source 110 supplies microwaves to the diamond photomagnetic sensor 120 via the coaxial cable. The λ / 4 variable 128 functions as an impedance converter. The λ / 4 stub 122 is, for example, an open-circuit λ / 4 stub. By using the λ / 4 variable 128, impedance can be precisely converted between the transmission circuit 126 (specifically, the coaxial cable with characteristic impedance Z1) and the resonator 124, enabling the efficient irradiation of the diamond 102 with electromagnetic waves.

[0072] With this configuration, the λ / 4 stub 122 and the λ / 4 variable 128 function as resonators, enabling the magnetic field of the microwaves from the microwave source 110 to be amplified and irradiated onto the diamond 102. Therefore, even if the power of the microwaves output from the microwave source 110 is lower than before, the diamond photomagnetic sensor 120 can still function as a magnetic sensor.

[0073] Reference Figure 3 The diagram illustrates the specific structure of the λ / 4 stub 122 and the λ / 4 variable 128. The λ / 4 stub 122 consists of two copper wires 132 and 134. Both copper wires 132 and 134 are λ / 4 open-circuit stubs. The diameter d of each copper wire 132 and 134 is 0.45 mm, and their length a1 is formed to be 20 mm in a λ / 4 manner relative to approximately 3 GHz microwaves (also taking into account the surrounding dielectric). The spacing b1 between copper wires 132 and 134 is 4 mm. A diamond 102 is disposed between copper wires 132 and 134. The diameter of each copper wire 132 and 134 can be approximately 50 μm or more and less than 2 mm. If the diameter is too small compared to 50 μm, it will heat up when the microwave output is high, causing the copper wire to break. Conversely, if the diameter is too large compared to 2 mm, the copper wire will extend out of the transmission circuit, hindering proper electrical matching of the circuit. In this combination (i.e., when using copper wire with the diameter range described above), the thickness of diamond 102 is preferably 1 μm or more and 0.3 mm or less.

[0074] The λ / 4 variable 128 comprises a dielectric substrate 140, a copper foil 130 disposed on the surface of the dielectric substrate 140, and a copper foil 138 disposed on the back side of the dielectric substrate 140. The dielectric substrate 140 is formed, for example, from glass epoxy resin. The copper foil 130 is connected to a copper wire 132. The copper foil 130 is composed of a first portion with a width w1 of 3 mm and a second portion with a width w2 of 10 mm. The length a2 of the second portion is 20 mm. The socket 136 is an SMA-type socket for mounting a coaxial cable plug. The center line (i.e., the signal line) of the socket 136 is connected to the copper foil 130, and the ground line of the socket 136 is connected to the copper foil 138. The copper foil 138 is connected to a copper wire 134.

[0075] The impedance of the λ / 4 stub 122, which is a λ / 4 open-circuit stub, is, for example, 300Ω. To increase the magnetic field applied to the diamond 102 by microwaves at the junction of the λ / 4 variable 128 and the λ / 4 stub 122 using a λ / 4 variable 128 with an impedance of 25Ω, it is preferable to adjust the position of the diamond 102 disposed on the λ / 4 stub 122. The distance e1 from the connection point of the λ / 4 stub 122 with the transmission circuit 126 (specifically, the λ / 4 variable 128) to the center of the diamond 102 is preferably 1 / 4 of the electrical length of the λ / 4 stub 122 (i.e., the λ / 4 open-circuit stub). However, a distance e1 within the range of (1 / 4) ± (1 / 8) of the electrical length of the λ / 4 stub 122 (i.e., a range of more than 1 / 8 and less than 3 / 8) is acceptable. The thickness of the diamond 102 in the spacing b1 direction is preferably greater than 0 and less than 0.3 mm. The length of the diamond 102 along the long side of the λ / 4 stub 122 (i.e., the λ / 4 open-circuit stub) is preferably less than 1 / 4 of the electrical length of the λ / 4 stub 122. By making the diamond 102 such a size, as described later, the magnetic field applied to the diamond 102 by microwaves can be increased.

[0076] The intensity of microwaves irradiating diamond 102, resulting from this configuration, was investigated. (Refer to...) Figure 4When microwaves are irradiated onto the diamond 102 using a coplanar waveguide, at the instant an upward current perpendicular to the plane of the paper flows through the conductor 902 in which the diamond 102 is disposed, a downward current perpendicular to the plane of the paper flows through the conductors 900 and 904 on both sides (refer to the lower front view). Since these are high-frequency currents, due to the skin effect and proximity effect, the current concentrates at the ends of conductors 900, 902, and 904. Therefore, as a magnetic field formed inside the diamond 102, magnetic fields H1 and H2 (shown by solid arrows) are formed due to the upward current perpendicular to the plane of the paper, and magnetic fields H3 and H4 (shown by dashed arrows) are formed due to the downward current perpendicular to the plane of the paper. These magnetic fields almost cancel each other out, resulting in a small combined magnetic field. On the other hand, referring to... Figure 5 ,in the case of Figure 3 In the structure shown, currents flow in opposite directions through copper wires 132 and 134, and the magnetic field they create inside diamond 102 is increased because the magnetic field H1 indicated by the solid arrow and the magnetic field H2 indicated by the dashed arrow are pointing in the same direction.

[0077] For example, with Figure 4 Compared to the coplanar waveguide shown (e.g., with an impedance of 50Ω), as described above, in Figure 3 In the structure shown, the short-circuit current flows through series resonance, thus the current becomes approximately twice as strong. Furthermore, the short-circuit current is also approximately twice as strong due to the impedance transition from 50Ω to 12.5Ω. Therefore, if the microwave power is the same, the total current flowing is approximately four times stronger. For example, through a coplanar waveguide, the magnetic field H formed by a current of 1A is H = 14.5 (A / m). On the other hand, in... Figure 3 In the structure shown, the magnetic field H generated by two parallel copper wires 132 and 134 spaced 4 mm apart, with a current of 1 A, is H = 70 (A / m), which is approximately 5 times that of a coplanar waveguide. Therefore, through... Figure 3 The structure shown allows for the application of [technology / method] to diamond 102. Figure 4 The total magnetic field is 20 times (=4×5) times that of the coplanar waveguide shown. Therefore, even if the power of the microwaves output from the microwave source 110 is lower than before, the diamond optical-magnetic sensor 120 can still function as a magnetic sensor.

[0078] (Third Implementation)

[0079] The above description explains how to increase the microwaves irradiating the diamond 102 through series resonance, but this is not the only method. In the third embodiment, the microwaves irradiating the diamond 102 are increased through parallel resonance. (See reference...) Figure 6The diamond optical-magnetic sensor 142 according to the third embodiment of this disclosure includes a diamond 102, a resonator 144, a transmission circuit 146, and a microwave source 110. This embodiment efficiently supplies microwaves to the diamond 102 through a resonator composed of a lumped constant circuit.

[0080] Resonator 144 includes coil L2 and capacitor C2, forming a parallel resonant circuit. Diamond 102 is disposed near coil L2 (including inside coil L2). Resonator 144 is an irradiation unit for irradiating microwaves onto diamond 102. Transmission circuit 146 includes impedance converter 148 and a coaxial cable with a characteristic impedance Z1 connecting impedance converter 148 to microwave source 110. Characteristic impedance Z1 is, for example, 50Ω. Microwave source 110 supplies microwaves to diamond photomagnetic sensor 142 via coaxial cable. Impedance converter 148 is specifically a transformer. By using a transformer in impedance converter 148, diamond photomagnetic sensor can be easily formed. With this configuration, resonator 144 and impedance converter 148 function as resonators, amplifying microwaves from microwave source 110 and irradiating diamond 102.

[0081] For example, if the turns ratio of the windings of the impedance converter 148 is set to 1:N (primary side:secondary side = 1:N) for impedance conversion, the open-circuit voltage on the load side (i.e., the LC parallel resonator) becomes N times. Therefore, even if the power of the microwaves output from the microwave source 110 is lower than before, the diamond photomagnetic sensor 142 can still function as a magnetic sensor.

[0082] (Fourth Implementation)

[0083] Reference Figure 7 The diamond optical-magnetic sensor 150 according to the fourth embodiment of this disclosure includes a diamond 102, a resonator 154, a transmission circuit 156, and a microwave source 110. This embodiment efficiently supplies microwaves to the diamond 102 through a resonator composed of high-frequency circuitry.

[0084] Resonator 154 includes a λ / 4 stub 152 and functions as a parallel resonant circuit. Diamond 102 is positioned near the λ / 4 stub 152. Resonator 154 is an irradiation unit for irradiating microwaves onto diamond 102. Transmission circuit 156 includes a λ / 4 variable 158 and a coaxial cable with a characteristic impedance Z1 connecting the λ / 4 variable 158 to microwave source 110. The characteristic impedance Z1 is, for example, 50Ω. Microwave source 110 supplies microwaves to diamond photomagnetic sensor 150 via the coaxial cable. λ / 4 variable 158 functions as an impedance converter. λ / 4 stub 152 is, for example, a λ / 4 short-circuit stub. By using λ / 4 variable 158, impedance can be precisely converted between transmission circuit 156 (specifically, the coaxial cable with characteristic impedance Z1) and resonator 154, enabling efficient irradiation of diamond 102 with electromagnetic waves.

[0085] With this configuration, the λ / 4 stub 152 and the λ / 4 variable 158 function as resonators, enabling the magnetic field of the microwaves from the microwave source 110 to be amplified and irradiated onto the diamond 102. Therefore, even if the power of the microwaves output from the microwave source 110 is lower than before, the diamond photomagnetic sensor 150 can still function as a magnetic sensor.

[0086] Reference Figure 8 The specific structure of the λ / 4 stub 152 and the λ / 4 variable 158 is shown. The λ / 4 stub 152 is made of a flat copper foil 164. The copper foil 164 is bent into a rectangle with one side removed, with a width w4 of 4 mm and a length a3 of 20 mm. That is, the copper foil 164 is formed in a structure where the two λ / 4 stubs are short-circuited at the bent portion of the copper foil 164 (hereinafter, the bent portion is referred to as the short-circuit end). The λ / 4 stub 152 is a λ / 4 short-circuited stub. The width w4 of the λ / 4 stub 152 is not limited to the above value. The width w4 of the λ / 4 stub 152 can be less than 1 / 2 of the length a3 of the λ / 4 stub 152. As a result, resonance can be achieved with less radiation.

[0087] The λ / 4 variable 158 is connected to the copper foil 164 and consists of two parallel copper wires 160 and 162. The length a4 of the copper wires 160 and 162 is 20 mm, and the spacing b2 is 4 mm. The socket 136 is an SMA type socket for mounting a coaxial cable plug. The center line (i.e., the signal line) of the socket 136 is connected to the copper wire 160, and the ground line of the socket 136 is connected to the copper wire 162. The diamond 102 is disposed within the space surrounded by the copper foil 164 (i.e., inside the copper foil 164).

[0088] The impedance of the λ / 4 stub 152, which is a λ / 4 short-circuit stub, is, for example, 100Ω. To convert the impedance using a λ / 4 variable 158 with an impedance of 300Ω, and to increase the magnetic field applied to the diamond 102 by microwaves at the junction of the λ / 4 variable 158 and the λ / 4 stub 152, it is preferable to adjust the position of the diamond 102 disposed on the λ / 4 stub 152. The distance e2 from the short-circuit end of the λ / 4 stub 152 to the center of the diamond 102 is preferably 1 / 4 of the electrical length of the λ / 4 stub 152 (i.e., the λ / 4 short-circuit stub). However, a distance e2 within the range of (1 / 4) ± (1 / 8) of the electrical length of the λ / 4 stub 152 (i.e., a range of more than 1 / 8 and less than 3 / 8) is acceptable. The thickness of the diamond 102 in the direction orthogonal to the λ / 4 stub 152 (i.e., the two parallel flat sections) is preferably 0.5 mm or more and 3 mm or less. The length of the diamond 102 along the long side of the λ / 4 stub 152 (i.e., the λ / 4 short-circuit stub) is preferably less than 1 / 4 of the electrical length of the λ / 4 stub 152. By making the diamond 102 such a size, as described later, the magnetic field applied to the diamond 102 by microwaves can be increased.

[0089] The intensity of the microwaves formed in diamond 102 due to this configuration was examined. As described above, when using... Figure 4 When the coplanar waveguide shown is irradiated with microwaves onto the diamond 102, the magnetic fields generated inside the diamond 102 cancel each other out, resulting in a small combined magnetic field. On the other hand, referring to... Figure 9 ,exist Figure 8 In the structure shown, currents flow in opposite directions in copper wires 160 and 162, and also in opposite directions in the parallel planar portion of copper foil 164. Because it is a high-frequency current, the current concentrates at the end of copper foil 164 due to the skin effect and proximity effect. Since the magnetic fields H1 and H3 indicated by the solid arrows are oriented in the same direction as the magnetic fields H2 and H4 indicated by the dashed arrows (i.e.,...), Figure 9 Above), therefore, the magnetic field formed inside the diamond 102 by the current flowing through the copper foil 164 is increased. Additionally, in Figure 9 In the copper foil 164, the current distribution is symmetrical about any direction, including the left-right direction and the up-down direction. Therefore, the left-right components of the magnetic field in the central region inside the copper foil 164 are canceled out, and the uniformity of the magnetic field becomes higher in the central region.

[0090] (Fifth Implementation)

[0091] In the above description, the second embodiment used a dielectric substrate such as glass epoxy resin and a λ / 4 stub formed by two copper wires. In contrast, the fifth embodiment uses a flexible substrate and a λ / 4 stub formed by four copper wires. (See reference...) Figure 10 The diamond optical-magnetic sensor 300 according to the fifth embodiment of this disclosure is composed of a diamond 102, a λ / 4 stub wire 302, a λ / 4 variable 304, and a socket 136.

[0092] The λ / 4 stub 302 is composed of four copper wires 310. The four copper wires 310 form a λ / 4 open-circuit stub. Each copper wire 310 has a diameter d of 0.45 mm and a length a8 of approximately 20 mm, λ / 4 relative to a microwave of approximately 3 GHz. The spacing g between the copper wires 310 is 2 mm. A diamond 102 is positioned at the center of the four copper wires 310.

[0093] The λ / 4 stub 302 is composed of a flexible substrate 306, a copper foil 308 disposed on the surface of the flexible substrate 306, and a copper foil 312 disposed on the back side of the flexible substrate 306. The copper foil 308 has a width w8 of 1 mm and a length a9 of approximately 15 mm. The center line (i.e., the signal line) of the socket 136 is connected to the copper foil 308, and the ground line of the socket 136 is connected to the copper foil 312. The impedance of the λ / 4 stub 302, which is an open-circuit λ / 4 stub, is, for example, 200 Ω, and the impedance of the λ / 4 variable 304 is, for example, 20 Ω. In order to increase the magnetic field applied to the diamond 102 by microwave at the junction of the λ / 4 variable 304 and the λ / 4 stub 302, it is preferable to adjust the position of the diamond 102 disposed on the λ / 4 stub 302 in the same manner as in the second embodiment.

[0094] right Figure 10 The intensity of microwaves formed on diamond 102 in the diamond optical-magnetic sensor 300 shown was investigated. (Refer to...) Figure 11 ,exist Figure 10 In the structure shown, the upper two of the four copper wires 310 (e.g., the copper wires connected to copper foil 308) carry current in the same direction, and the lower two (e.g., the copper wires connected to copper foil 312) carry current in the same direction. The current direction on the upper side is opposite to the current direction on the lower side. In the diamond 102, magnetic fields H5 and H6 (refer to the arrows on the solid lines) are formed through the upper two copper wires 310, and magnetic fields H7 and H8 (refer to the arrows on the dashed lines) are formed through the lower two copper wires 310. Magnetic fields H5 and H8 are oriented in the same direction, i.e. Figure 11 The magnetic fields reinforce each other in the upward-southward direction. Magnetic fields H6 and H7 point in the same direction, i.e. Figure 11 The magnetic fields reinforce each other in the downward-sloping right direction.

[0095] A rightward composite magnetic field is formed by magnetic fields H5 to H8. That is, a magnetic field can be applied in a direction parallel to the surface of the flexible substrate 306. On the other hand, as described above, if... Figure 3 as well as Figure 8 The structure can generate a magnetic field in a direction perpendicular to the substrate (see reference). Figure 5 as well as Figure 9 Based on the crystal orientation of diamond 102, the direction of the NV center, the orientation of the NV center, the excitation light irradiation, and the fluorescence focusing layout, the orientation of the microwave magnetic field relative to the substrate can be either vertically or horizontally suitable. In the case of a suitable vertical orientation, for example, it is possible to use... Figure 3 or Figure 8 The structure shown. Under suitable horizontal conditions, for example, it is possible to use... Figure 10 The structure shown.

[0096] In the first to fifth embodiments described above, microwave power can be supplied either via a wired connection or via wireless transmission in space. As an example of the wired case, an SMA socket is shown connected to the transmission circuit. On the other hand, in the wireless case, for example, as... Figure 12 As shown, this can be configured as a transmission circuit that receives microwaves via a monopole antenna and supplies power to the resonator side directly connected to the monopole antenna. (Refer to...) Figure 12 The diamond optical-magnetic sensor 330 comprises a diamond 102, a λ / 4 stub 332, a λ / 4 variable rectifier 334, and a monopole antenna 336. The λ / 4 stub 332 is composed of a linear conductor 342 (e.g., copper wire) and a portion of a linear conductor 338 (e.g., copper wire) (i.e., the portion corresponding to the linear conductor 342). The λ / 4 stub 332 is an open-circuit λ / 4 stub. The λ / 4 variable rectifier 334 is composed of a flexible substrate 340, a copper foil 344, and a portion of the linear conductor 338 (i.e., the portion opposite to the copper foil 344). The characteristic impedance of the monopole antenna 336 is, for example, 37Ω, and the characteristic impedances of the λ / 4 variable rectifier 334 and the λ / 4 stub 332 are, for example, 20Ω and 200Ω, respectively. That is, microwaves are received by the monopole antenna 336, converted to low impedance, and resonated in series through the λ / 4 open-circuit stub.

[0097] (First variation)

[0098] In the above description, a second embodiment was given using a dielectric substrate (e.g., glass epoxy resin), but the embodiment is not limited to this. The diamond photomagnetic sensor in the first variation uses a flexible substrate.

[0099] Reference Figure 13 The diamond optical-magnetic sensor 170 involved in the first variation example and Figure 3 Compared to the diamond optical-magnetic sensor 120 shown, the structures of the λ / 4 stub 122 and the λ / 4 variable 128 are different. The λ / 4 stub 122 is composed of a flexible substrate 172, a copper foil 174 disposed on the surface of the flexible substrate 172, and a copper foil 178 disposed on the back side of the flexible substrate 172. The flexible substrate 172 is formed of a film-like polyimide. The width w5 of both copper foils 174 and 178 is 0.5 mm, the length a5 is 20 mm, and the interval b3 between them is 4 mm. Copper foils 174 and 178 are λ / 4 open-circuit stubs. The λ / 4 variable 128 is composed of the flexible substrate 172, a copper foil 176 disposed on the surface of the flexible substrate 172 and connected to the copper foil 174, and a copper foil 180 disposed on the back side of the flexible substrate 172 and connected to the copper foil 178. The copper foil 176 has a width w6 of 1 mm and a length a6 of 15 mm. The flexible substrate 172 forms both the λ / 4 stub 122 and the λ / 4 variable 128, therefore its length (i.e., a5 + a6) is 35 mm. The center line (i.e., the signal line) of the socket 136, which serves as the plug for assembling a coaxial cable, is connected to the copper foil 176, and the ground line of the socket 136 is connected to the copper foil 180. A diamond 102 is disposed between the copper foils 174 and 178, cutting away the space of the flexible substrate 172. The characteristic impedance of the socket 136 is 50 Ω. The characteristic impedances of the λ / 4 variable 128 and the λ / 4 stub 122 are 20 Ω and 200 Ω, respectively.

[0100] Diamond optical-magnetic sensor 170 and Figure 3 The structure shown also functions as a series resonant circuit, making it similar to the previous one (see reference). Figure 4 Compared to the increased short-circuit current flowing through it, the diamond optical-magnetic sensor 170 also... Figure 5 As shown, similarly to the past (refer to...) Figure 4 Compared to the previous method, this method can increase the strength of the magnetic field formed inside the diamond 102. Therefore, even if the power of the microwaves output from the microwave source 110 is lower than before, the diamond optical-magnetic sensor 170 can still function as a magnetic sensor.

[0101] (Second variation)

[0102] In the first variation described above, a linear copper foil was used as the λ / 4 stub 122, but the invention is not limited to this. The diamond photomagnetic sensor involved in the second variation uses a planar copper foil as the λ / 4 stub 122.

[0103] Reference Figure 14 The second variation involves the diamond optical-magnetic sensor 182 and Figure 13Compared to the diamond optical-magnetic sensor 170 shown, the structure of the λ / 4 stub 122 is different. The λ / 4 stub 122 is composed of copper foil 184 and copper foil 186. The width w7 of each copper foil 184 and copper foil 186 is 4 mm, the length a7 is 20 mm, and the interval b4 between them is 4 mm. Copper foil 184 and copper foil 186 are λ / 4 open-circuit stubs. The flexible substrate 188 is formed of a film-like polyimide, similar to the diamond optical-magnetic sensor 170, and its length a6 (a6 = 15 (mm)) is shorter than the length of the flexible substrate 172 of the diamond optical-magnetic sensor 170 (i.e., a5 + a6). The diamond 102 is disposed between the copper foil 184 and copper foil 186. The characteristic impedance of the socket 136 is 50 Ω. The characteristic impedances of the λ / 4 variable 128 and the λ / 4 stub 122 are 20 Ω and 200 Ω, respectively.

[0104] Diamond optical-magnetic sensor 182 and Figure 3 The structure shown also functions as a series resonant circuit, making it similar to the previous one (see reference). Figure 4 Compared to the increased short-circuit current flowing through it, the diamond optical-magnetic sensor 182 also... Figure 5 As shown, similarly to the past (refer to...) Figure 4 Compared to previous methods, this method can increase the strength of the magnetic field formed inside the diamond 102. Therefore, even if the power of the microwaves output from the microwave source 110 is lower than before, the diamond optical-magnetic sensor 182 can still function as a magnetic sensor.

[0105] The above description illustrates the case where the λ / 4 variable 128 is formed by a λ / 4 stub (i.e., copper foil) of a predetermined width w2, but it is not limited to this. Figure 15 As shown, it can be a λ / 4 variable whose width w changes in stages, such as... Figure 16 As shown, it can also be a λ / 4 variable whose width w changes smoothly in a conical shape. They can be used for... Figure 3 The diamond optical-magnetic sensor constructed from the λ / 4 variable 128 shown above can also function as a magnetic sensor even if the power of the microwaves output from the microwave source 110 is lower than before.

[0106] The above description focuses on impedance converters that are transformers or λ / 4 variable transformers, but is not limited to these. Microstrip lines can also be used as impedance converters. The width of the microstrip line is preferably less than half its length. By using microstrip lines in the impedance converter, impedance can be easily and accurately converted between the microwave source and the microwave irradiation section.

[0107] 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.

[0108] Example 1

[0109] The following examples illustrate the effectiveness of this disclosure. Figure 17 The measuring apparatus shown measures the fluorescence intensity emitted from the NV center by irradiating a diamond with an NV center with excitation light. (Refer to...) Figure 17 The structure (i.e., the irradiation system) in the measuring apparatus 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. The structure (i.e., the microwave system) for irradiating the diamond 210 with microwaves includes a microwave source (not shown) and a coaxial cable 220, in which the microwaves transmitted are shared by the resonators constituting the diamond optical-magnetic sensor 216.

[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 S06-RG manufactured by Suruga Seiki Co., Ltd. The excitation light (i.e., green light) incident on the dichroic mirror 204 is reflected. This 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 optic 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 a resonator for the diamond optical-magnetic sensor 216, it is used Figure 3 The resonator of the diamond optical-magnetic sensor 120 shown Figure 8 The resonator of the diamond optical-magnetic sensor 150 shown is... Figure 10 The resonator of the diamond optical-magnetic sensor 300 is shown. Their respective structures and dimensions are as described above. As a comparative example, a... Figure 18 The structure and dimensions of the microstrip resonator shown are as follows: Figure 19 The resonator is a coplanar waveguide with the structure and dimensions shown. Figure 18 In this process, a conductor acting as a ground wire is integrally disposed on the back side of a dielectric substrate containing microstrip lines. The diamond is a cubic diamond, as described later, disposed on... Figure 18 as well as Figure 19 The positions shown are indicated. At each resonator (refer to...) Figure 3 , Figure 8 , Figure 10 , Figure 18 as well as Figure 19 The socket is equipped with a 220mm coaxial cable plug (in) Figure 17 (Not shown in the image), it supplies microwaves. Furthermore, in Figure 18 as well as Figure 19 In the resonator shown, the socket not connected to coaxial cable 220 is terminated with a 50Ω terminating resistor.

[0113] The same diamond was used, and measurements were performed using the structures disclosed herein and those of comparative examples. Specifically, 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 2Electrons were injected into it, and then it was annealed at 800°C for about 1 hour to produce diamond containing NV centers. It was then cut into cubes with a side length of 1 mm to make diamond 210 used in the measurements.

[0114] Microwaves (1W) generated by a microwave generating device (not shown) are transmitted to a diamond optical-magnetic sensor 216 using a coaxial cable 220. The coaxial cable 220 uses a coaxial cable with a characteristic impedance of 50Ω. The power of the microwave supplied to the coaxial cable 220 is varied within the range of -16dBm to 30dBm. Furthermore, the frequency of the microwave is varied within the range of 2.74GHz to 2.94GHz. If the microwave power is kept constant while the microwave frequency is varied, then... Figure 20 As shown, 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 value obtained by dividing the valley size S of the graph by the fluorescence intensity S0) as the rate of decrease in red luminance can be calculated. As a theoretical formula for the sensitivity δB (i.e., the resolution of the detected magnetic field B) of the diamond photomagnetic sensor, Equation 1 is known, and the spin detection contrast ratio affects the sensitivity δB.

[0115] [Number 1]

[0116]

[0117] 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. 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, the smaller the sensitivity δB, and the higher the sensitivity.

[0118] Regarding the above five types of resonators (refer to...) Figure 3 , Figure 8 , Figure 10 , Figure 18 as well as Figure 19 As described above, the microwave power was varied, and the valleys of fluorescence intensity (i.e., red luminance) were observed to calculate the spin detection contrast ratio. The results are presented in... Figure 21 .exist Figure 21 In the middle, the white circle indicates that it was used. Figure 3 The result shown is from a resonator with an open stub of λ / 4. The black circle indicates the use of... Figure 8 The result shown is a resonator with a λ / 4 short-circuited stub. The white triangle is achieved using... Figure 10The result shown is a resonator with an open stub of λ / 4. The white squares represent the resonators used. Figure 18 The result shown is from a microstrip resonator. The black squares represent the resonators used. Figure 19 The results of the resonator shown are from the coplanar waveguide.

[0119] from Figure 21 It can be seen that by using a resonator with an open stub of λ / 4 (refer to...) Figure 3 Using comparative examples (see reference) Figure 18 as well as Figure 19 A microwave with approximately 25 dB less power (i.e., 1 / 300th the power) achieved an equivalent spin detection contrast ratio. This was achieved by using a resonator with a λ / 4 short-circuited stub (see reference). Figure 8 Using microwaves with approximately 10 dB less power than the comparative example (i.e., 1 / 10 of the power), an equivalent spin detection contrast ratio was obtained. Furthermore, a resonator with four copper wires arranged in parallel with λ / 4 open-circuit stubs (see [reference]) was also achieved. Figure 10 A resonator using a λ / 4 open-circuit stub with two copper wires arranged in parallel (see reference). Figure 3 A microwave with 2 dBm less power was used to achieve the same spin detection contrast ratio. Thus, by using the resonator disclosed herein, the diamond photomagnetic sensor can function even with microwaves of significantly lower power than before.

[0120] Example 2

[0121] Using the structure of the second embodiment (see reference) Figure 3 The diameters of the copper wires 132 and 134 constituting the λ / 4 stub and the size of the diamond are changed, as in Example 1 described above (refer to Example 1). Figure 17 The same experiment was conducted. Specifically, copper wires with diameters of 0.1 mm, 0.3 mm, 1.0 mm, and 1.5 mm were used as copper wires 132 and 134. As comparative examples, copper wires with diameters of 0.02 mm and 3 mm were used as copper wires 132 and 134. Diamond 210 (refer to...) Figure 17 Diamonds with thicknesses of 0.8μm, 10μm, 0.1mm, 0.3mm and 0.5mm were used.

[0122] The result was the same as in Example 1, achieved when using copper wires with diameters of 0.1 mm, 0.3 mm, 1.0 mm, and 1.5 mm. That is, the same results were obtained as in Example 1. Figure 21The results shown by the white circle (i.e., when the diameters of copper wires 132 and 134 are 0.45 mm) show the same spin detection contrast ratio. However, when using copper wires with a diameter of 0.02 mm for copper wires 132 and 134, the temperature of the copper wires rises, and the resistance increases. If the temperature rise is allowed to continue under high microwave output conditions, the copper wires will break. Furthermore, when using copper wires with a diameter of 3 mm for copper wires 132 and 134, the wires are too thick, making it impossible to achieve resonant matching, and the spin detection contrast ratio drops below 0.001.

[0123] Regarding Diamond 210 (see reference) Figure 17 For samples with thicknesses of 10 μm and 0.1 mm, the same results as in Example 1 were obtained, i.e., the same as in Example 1. Figure 21 The results shown in the white circle exhibit the same spin detection contrast ratio. On the other hand, for the diamond 210 sample with a thickness of 0.8 μm, the fluorescence intensity decreases, making light detection difficult. Compared to the 0.3 mm sample, the spin detection contrast ratio of the diamond 210 sample with a thickness of 0.5 mm decreases to less than 1 / 10.

[0124] 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.

[0125] Explanation of reference numerals in the attached figures

[0126] 100, 120, 142, 150, 170, 182, 216, 300, 330: Diamond optical-magnetic sensors;

[0127] 102, 210: Diamond;

[0128] 104, 124, 144, 154: Resonators;

[0129] 106, 126, 146, 156: Transmission circuits;

[0130] 108, 148: Impedance converters;

[0131] 110: Microwave source;

[0132] 122, 152, 302, 332: λ / 4 stubs;

[0133] 128, 158, 304, 334: λ / 4 variable transducers;

[0134] 130, 138, 164, 174, 176, 178, 180, 184, 186, 308, 312, 344: Copper foil;

[0135] 132, 134, 160, 162, 310: Copper wire;

[0136] 136: Socket;

[0137] 140: Dielectric substrate;

[0138] 172, 188, 306, 340: Flexible substrates;

[0139] 200: Light source;

[0140] 202: Collimating lens;

[0141] 204: Dichroic mirror;

[0142] 206: Spherical lens;

[0143] 208: Optical fiber;

[0144] 212: LPF;

[0145] 214: Photodetector;

[0146] 220: Coaxial cable;

[0147] 336: Monopole antenna;

[0148] 338, 342: Linear conductors;

[0149] 900, 902, 904: Conductors;

[0150] a1, a2, a3, a4, a5, a6, a7, a8, a9: Length;

[0151] b1, b2, b3, b4, g: intervals;

[0152] C1, C2: Capacitors;

[0153] d, d1: Diameter;

[0154] e1, e2: Distance;

[0155] H1, H2, H3, H4, H5, H6, H7, H8: Magnetic fields;

[0156] L1, L2: Coils;

[0157] w1, w2, w4, w5, w6, w7, w8: Width;

[0158] Z1: Impedance.

Claims

1. A diamond optical-magnetic sensor, wherein, The diamond optical-magnetic sensor includes: Diamond has color centers with electron spin; Transmission circuits that transmit electromagnetic waves; and An irradiation section that irradiates the diamond with the electromagnetic waves transmitted by the transmission circuit. The transmission circuit includes an impedance converter, which is used to make the impedance of the electromagnetic source that outputs the electromagnetic wave lower or higher when viewed from the irradiation section. The irradiation section includes a resonator. The resonator includes a λ / 4 stub. The λ / 4 stub includes a λ / 4 open-circuit stub. The center of the diamond is located within a predetermined range from the connection end of the λ / 4 open stub to the transmission circuit. The predetermined range is more than 1 / 8 and less than 3 / 8 of the electrical length of the λ / 4 open-circuit stub. The length of the diamond along the long side of the λ / 4 open stub is less than 1 / 4 of the electrical length.

2. A diamond optical-magnetic sensor, wherein, The diamond optical-magnetic sensor includes: Diamond has color centers with electron spin; Transmission circuits that transmit electromagnetic waves; and An irradiation section that irradiates the diamond with the electromagnetic waves transmitted by the transmission circuit. The irradiation section includes a resonator. The resonator includes a λ / 4 stub. The λ / 4 stub includes a λ / 4 short-circuit stub. The center of the diamond is located within a predetermined range from the short-circuited end of the λ / 4 short-circuit stub. The predetermined range is more than 1 / 8 and less than 3 / 8 of the electrical length of the λ / 4 short-circuit stub. The length of the diamond along the long side of the λ / 4 short-circuit stub is less than 1 / 4 of the electrical length.

3. The diamond optical-magnetic sensor according to claim 2, wherein, The transmission circuit includes an impedance converter, which is used to make the impedance of the electromagnetic source that outputs the electromagnetic wave lower or higher when observed from the irradiation section.

4. The diamond optical-magnetic sensor according to claim 1 or 3, wherein, The impedance converter includes a transformer.

5. The diamond optical-magnetic sensor according to claim 1 or 3, wherein, The impedance converter includes a λ / 4 variable.

6. The diamond optical-magnetic sensor according to any one of claims 1 to 3, wherein, The λ / 4 stub contains two linear conductors arranged in parallel.

7. The diamond optical-magnetic sensor according to any one of claims 1 to 3, wherein, The λ / 4 stub contains four linear conductors arranged in parallel.

8. The diamond optical-magnetic sensor according to any one of claims 1 to 3, wherein, The λ / 4 stub contains two flat conductors. The two flat conductive plates are arranged in parallel opposite each other.

9. The diamond optical-magnetic sensor according to claim 6, wherein, The thickness of the diamond is greater than 0 and less than 0.3 mm. The two linear conductors are configured to sandwich the diamond and are spaced apart in the thickness direction of the diamond.

10. The diamond optical-magnetic sensor according to claim 8, wherein, The thickness of the diamond is 0.5 mm or more and 3 mm or less. The two plate-shaped conductors are configured to sandwich the diamond and are spaced apart in the thickness direction of the diamond.

11. The diamond optical-magnetic sensor according to claim 5, wherein, The λ / 4 variable is formed as a cone with a continuously varying width.

12. The diamond optical-magnetic sensor according to claim 5, wherein, The λ / 4 variable is formed as a multi-level type with discretely varying width.

13. The diamond optical-magnetic sensor according to claim 5, wherein, The impedance converter includes microstrip lines. The width of the microstrip line is less than 1 / 2 of the length of the microstrip line.

14. The diamond optical-magnetic sensor according to any one of claims 1 to 3, wherein, The width of the λ / 4 stub is less than 1 / 2 of the length of the λ / 4 stub.

Images