Sensor system for detecting a medium

Abstract

The invention relates to a magnetic field sensor (1) for detecting a magnetic field with a magneto-optic material (2), an excitation light source (3) configured to emit excitation radiation to excite electronic states of the magneto-optic material (2), a microwave source (4) configured to generate an electromagnetic field to supply a resonator structure (8), a detector (5) configured to detect fluorescence radiation that the magneto-optic material (2) can emit as a result of irradiation with the excitation radiation, and a magnetic field generation device (6) arranged and configured to generate a permanent magnetic field in the region of the magneto-optic material (2).The magnetic field sensor (1) further comprises a resonator structure (8) arranged on a dielectric (7), which is configured to shape the electromagnetic field emitted by the microwave source (4) such that a microwave field is generated which is suitable for manipulating spin states of the magneto-optic material (2). The magneto-optic material (2), the excitation light source (3), the detector (5) and the microwave structure (8) are arranged in a closed space (9).

Description

The present invention relates to a magnetic field sensor based on an NV diamond.Prior ArtFor some years, diamond crystals whose crystal lattices have defects in the form of NV centers have been the subject of research. In an NV center, a nitrogen atom occupies the lattice site of a carbon atom, wherein a defect is arranged in direct proximity to the nitrogen atom-again on the lattice site of a carbon atom. If such a crystal lattice is irradiated with excitation radiation having a wavelength between 490 nm and 575 nm, an electronic transition from a ground state 3 A 2 to an excited state 3 E is induced in the crystal lattice. From the excited state 3 E, the NV center relaxes again into the ground state 3 A 2. with emission of fluorescent radiation in a wavelength range between 600 nm and 850 nm.The ground state 3 A 2 has three magnetic substates with m s=0, m s= ±1. The states with m s=0 and m s= ±1 differ by an energy difference of 2.87 GHz (zero field splitting). If the NV center in the ground state 3 A 2 is now exposed to an alternating magnetic field with a frequency of 2.87 GHz (usually and below, alternating magnetic fields in a frequency range between 1 and 4 GHz are referred to as "microwave field"), the NV center oscillates between the m s=0,3 A 2- ground state and the m s= ±1, 3 A 2- ground state. When irradiated with the excitation radiation, the NV center is now partially shifted from the m s= ±1, 3 A 2- ground state into the excited m s= ±1, 3 E state. From there, it relaxes again to the basic state predominantly without radiation.If the intensity of the fluorescent radiation is measured as a function of the frequency of the microwave field, then at a frequency of 2.87 GHz, a sudden drop in the intensity of the fluorescent radiation (a so-called peak) results. The drop in the intensity of the fluorescent radiation can be explained by the fact that--when the microwave field is irradiated at a frequency of 2.87 GHz--fewer NV centers are available in the m s=0,3 A 2- ground state, which centers are optically excited and can relax to the m s= ±1, 3 A 2- ground state with emission of fluorescent radiation.In an external magnetic field, the m s= ±1, 3 A 2- ground state splits into two states with the spin quantum number m s=1 and m s=-1 (Zeemann effect). If the intensity of the fluorescent radiation is now measured by changing the frequency of the microwave field, two peaks are obtained. The frequencies at which these peaks occur depend on the magnitude of the splitting of the m s= ±1, 3 A 2- ground state and thus on the field strength of the external magnetic field.Such a magnetic field sensor is, for example. From DE 10 2020 204 732. Herein, the excitation radiation is generated with the aid of a laser diode which is arranged in a cavity. The cavity is formed by a recess in a carrier wafer and a glass substrate which hermetically seals the cavity. The excitation radiation is directed through the glass substrate into an underlying plane where it is focused on an NV diamond. The lower plane comprises a substrate on which the remaining system components such as diamond, a radio frequency device, photodetectors and further optical components are arranged. The substrate is sealed with a cap substrate containing an opening through which the excitation radiation can pass onto the diamond. The laser diode is thus arranged separately from the remaining components of the magnetic field sensor in its own enclosed space. Such a magnetic field sensor with two separate cavities requires space and cannot be miniaturized further. In addition, the alternating magnetic field generated by the high-frequency device can freely propagate, so that the characteristic of the high-frequency device is influenced by materials in the environment of the magnetic field sensor. This can influence the specification of the magnetic field sensor and thus prevent the magnetic field sensor from being universally usable. In addition, components arranged outside the magnetic field sensor can be disturbed by the alternating magnetic field and the electromagnetic compatibility of the magnetic field sensor can be restricted.It is an object of the invention to provide a magnetic field sensor which does not have the disadvantages of the prior art.Disclosure of the InventionThe present invention relates to a magnetic field sensor for detecting a magnetic field according to claim 1.The invention provides a magnetic field sensor for detecting a magnetic field, comprising a magneto-optical material, an excitation light source, a microwave source and a detector. The magneto-optical material can be diamond crystals whose crystal lattices have defects in the form of NV centers. The excitation light source is configured to emit excitation radiation for exciting electronic states of the magneto-optical material. The excitation light source can be a laser diode having a wavelength between 490 nm and 575 nm. The microwave source is configured to generate an electromagnetic field which can feed a resonator structure, i.e. can be supplied to a resonator structure. The detector is configured to detect fluorescent radiation that the magneto-optical material can emit as a result of irradiation with the excitation radiation. Furthermore, the magnetic field sensor has a magnetic field generating device which is arranged and designed to generate a permanent magnetic field in the region of the magneto-optical material.The resonator structure is arranged on a dielectric and designed to amplify the electromagnetic field generated by the microwave source at least in a predefined frequency band and to shape it such that a homogeneous microwave field can form in the region of the magneto-optical material. The microwave field thus generated is suitable for manipulating spin states of the magneto-optical material and has, for example, one or more frequencies in a frequency band between 2.5 GHz and 3 GHz.Deposition of organic substances on the optical components, particularly on the excitation light source, is problematic. In order to protect the magneto-optical material, the excitation light source, the detector and the resonator structure here from and from other environmental influences, these are arranged in a closed space. The magneto-optical material, the excitation light source, and the detector may also be disposed on the dielectric. Arranging the magneto-optical material, the excitation light source, the detector and the resonator structure in a closed, in particular hermetically sealed, space makes it possible to make the magnetic field sensor compact. In addition, the spatial proximity of the resonator structure to the magneto-optical material allows the microwave field amplified and shaped by the resonator structure to be coupled into the magneto-optical material efficiently and largely loss-free.In this case, a first metallic layer can be arranged below the resonator structure arranged on the dielectric and a second metallic layer can be arranged above the resonator structure arranged on the dielectric. The first and the second metallic layer are in particular configured to shield the microwave field amplified and shaped by the resonator structure from an upper side and a lower side of the enclosed space. In addition, the first and / or the second metallic layer are configured to form the microwave field amplified by the resonator structure.In this way, both the microwave field can be shielded from the surroundings of the enclosed space and the electronic and optical components of the magnetic field sensor can be protected from the surroundings.The first and / or second metallic layer are in particular designed as a ground plane, which is connected to an electrical ground of the microwave source. In this case, characteristic impedance, shape and propagation speed of the electromagnetic microwave field are influenced, inter alia, by the material of the dielectric and by the position of the first and / or second metallic layer connected to ground.The resonator structure can comprise an electrically conductive structure which is arranged on the dielectric and is embodied, for example, as an omega resonator, as a planar slot waveguide structure or as a loop gap resonator. The resonator structure forms a resonator together with the dielectric on which it is arranged and the first and / or second metallic layer formed as a ground plane. The characteristic impedance, shape and propagation speed of the electromagnetic microwave field are determined, inter alia, by the material of the dielectric and the position of the first and second metallic layers connected to the ground. The geometry of the resonator is selected such that the microwave field is generated such that it is homogeneous in a region in which the magneto-optical material is arranged and locally limited to this region. The resonator is in particular configured to amplify frequencies in one or more frequency bands in the range between 2.5 and 3.1 GHz. Outside these frequency bands, it may be that the efficiency of the field generation falls so much that the power of the microwave source is no longer sufficient for a reasonable operation of the magnetic field sensor.Compared to a commonly used, current-carrying wire which is brought into the vicinity of the magneto-optical material, the use of the resonator structure has the advantage that a microwave field can be generated very efficiently. Accordingly, the microwave source can have a lower power and can be dimensioned correspondingly smaller, so that the magnetic field sensor can be constructed compactly.According to a further development of the invention, a base surface and four side surfaces are formed on a housing, in particular a one-piece housing, wherein the housing has a dielectric at least on the base surface and the resonator structure is arranged on the base surface. For closing the housing, a separate cover is provided, on the side of which - facing the components of the magnetic field sensor - a cover surface is provided. In this further development of the invention, the four side surfaces, the base surface and the ceiling surface form the enclosed space. The housing can be constructed completely or partially from a dielectric, for example from a dielectric plastic. The use of a housing facilitates the production of the magnetic field sensor, since such a housing, a so-called package, is simple and inexpensive to provide.According to a further development of the invention, the magnetic field sensor has a closure, in particular a one-piece closure, wherein the cover surface and the four side surfaces are formed on the closure. In this case, the base surface may be formed on a first dielectric substrate. The resonator structure is arranged in particular on the base surface, in this case on the first dielectric substrate. The first dielectric substrate has a dielectric or is formed completely or partially from a dielectric, for example a dielectric plastic. In this further development of the invention, the four side surfaces, the base surface and the ceiling surface also form the closed space. Such a closure is also simple and cost-effective to provide, so that such a magnetic field sensor is simple and cost-effective to produce.According to a further development of the invention, the housing or the first dielectric substrate is arranged on a printed circuit board. In this case, a gap can be arranged between the printed circuit board and the housing or the printed circuit board and the first dielectric substrate. The gap may be filled with air or a dielectric material. The arrangement of the housing or of the first dielectric substrate on the printed circuit board enables simple contacting of those components of the magnetic field sensor which are arranged in the closed space, and also simple mounting of the magnetic field sensor.The thickness of the gap can influence the characteristic impedance of the resonator as well as the propagation speed of the microwave field, which in turn influences the resonant frequency. Only a slight variation in the thickness of the gap can change the resonant frequency very greatly-up to a resonant frequency at which the magnetic field sensor can no longer be operated meaningfully.The housing or the first dielectric substrate can also be arranged directly on the printed circuit board. This enables simple and cost-effective production of the magnetic field sensor.According to a further development of the invention, the resonator structure is surrounded by a third metallic layer likewise arranged on the dielectric. The third metallic layer can be arranged such that the resonator structure is surrounded completely or partially by the third metallic layer towards the four side surfaces. The third metallic layer can be connected to the electrical ground of the microwave source. The sensitivity of the resonant frequency to the thickness of the gap can be reduced by arranging the third metallic layer on the dielectric around the resonator structure.According to a further development of the invention, the resonator structure is arranged on a side of the first dielectric substrate facing the closed space and the first metallic layer is arranged on an opposite side of the first dielectric substrate. In particular, the first dielectric substrate is arranged in the housing, wherein the first metallic layer is arranged on the side of the first dielectric substrate facing the base surface of the housing and the resonator structure is arranged on the side of the dielectric substrate facing away from the base surface of the housing (and thus facing the enclosed space). In this further development of the invention, the side of the dielectric substrate facing away from the base surface, the four side walls and the cover surface formed on the cover form the closed space. The first dielectric substrate can consist entirely or partially of a dielectric, for example a dielectric plastic. Such a configuration enables simple assembly and thus a cost-effective configuration of the magnetic field sensor.In a further development of the invention, the second metallic layer is arranged on a second dielectric substrate. The second dielectric substrate is arranged in particular on the ceiling surface of the cover, wherein the second metallic layer is arranged on the side of the second dielectric substrate that faces away from the ceiling surface (and thus faces the enclosed space). Additionally or alternatively, a fourth metallic layer can be arranged opposite the second metallic layer and thus on the side of the second dielectric substrate which faces the ceiling surface. Such a configuration enables simple assembly and thus cost-effective configuration of the magnetic field sensor.In a further development of the invention, the first metallic layer is designed as a cooling block. This enables a particularly compact construction of the magnetic field sensor, since an additional cooling block or an additional metallic layer can be dispensed with.In a further development of the invention, a fifth metallic layer is arranged parallel to one of the side surfaces of the enclosed space. This improves the shielding of the microwave field amplified by the resonator structure. The fifth metallic layer can be electrically connected to the second and / or first metallic layer and / or further metallic layers, for example by contacts.The resonator structure can be produced with the aid of a laser, for example by laser structuring. This allows the resonator structure to be produced easily, precisely and cost-effectively.Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawing.The invention is schematically illustrated in the drawing on the basis of exemplary embodiments and is described below with reference to the drawing.Brief Description of the DrawingsFIG. 1 shows a magnetic field sensor according to an embodiment of the invention, in which a magneto-optical material, an excitation light source, a detector and a resonator structure are arranged on a dielectric in a confined space; FIG. 2 shows a further exemplary embodiment of a magnetic field sensor according to the invention, in which the magneto-optical material, the excitation light source, the detector and the resonator structure are arranged on a base surface of a housing and wherein a metallic layer is arranged below the base surface of the housing; FIG. 3 also shows a further embodiment of a magnetic field sensor according to the invention, wherein the magneto-optical material, the excitation light source, the detector and the resonator structure are arranged on a first dielectric substrate; FIG. 4 also shows a further embodiment of a magnetic field sensor according to the invention, wherein the magnetic field sensor comprises a second dielectric substrate in addition to the first dielectric substrate; FIG. 5 shows a further exemplary embodiment of the magnetic field sensor according to the invention, wherein a metallic layer is provided, which is configured as a cooling block; FIG. 6 shows a further exemplary embodiment of the magnetic field sensor according to the invention, wherein the magnetic field sensor has metallic layers on its side surfaces; FIG. 7 shows a further exemplary embodiment of the magnetic field sensor according to the invention, wherein the metallic layers on the side surfaces are connected to the metallic layers on the base surface and a ceiling surface; FIG. 8 shows an embodiment of the magnetic field sensor in a plan view.Embodiments of the InventionFIG. 1 shows a magnetic field sensor 1, wherein a magneto-optical material 2, for example a diamond with NV defects, as well as an excitation light source 3, which is designed as a laser diode, for example, and a detector 5 are arranged on a dielectric 7. A resonator structure 8 is furthermore arranged on the dielectric. This is designed to amplify and shape an alternating electromagnetic field generated by a microwave source in a predefined frequency band, so that a homogeneous microwave field is formed in the region of the magneto-optical material 2. In FIG. 1, field lines of the microwave field 41 can be seen. A first metallic layer 11 may be arranged on the underside of the dielectric 7. The excitation light source 3, the magneto-optical material 2 and the detector 5 are arranged in a closed space.The excitation light source 3 is designed to emit excitation radiation having a wavelength between 490 nm and 575 nm. If the magneto-optical material 2 is irradiated with the excitation radiation, an electronic state of the magneto-optical material 2 can be excited, which relaxes back into the basic state with emission of fluorescence radiation. Now, if the microwave field has a suitable frequency, for example. 2.87 MHz, simultaneously exciting spin states of the magneto-optical material 2, the intensity of the emitted fluorescent radiation decreases, since the ground state from which the excitation takes place into an excited state is less likely to be occupied. The intensity of the fluorescent radiation can be detected with the detector 5.With the aid of a microwave source, an alternating electromagnetic field is generated, which is amplified and shaped by the resonator structure 8 arranged on the dielectric 7, so that a microwave field 41 is present where the magneto-optical material 2 is arranged. The first metallic layer 11 delimits the microwave field 41 at the bottom 13, but not at the top 12, so that it can freely propagate at the top. As a result, the characteristic of the microwave field 41 generated by the resonator structure 8 can be influenced by the vicinity of the magnetic field sensor 1, and the magnetic field sensor 1 cannot be universally used. Furthermore, components arranged outside the magnetic field sensor 1 can also be disturbed by the generated microwave field 41, so that such a magnetic field sensor 1 does not meet the requirements with regard to electromagnetic compatibility.In addition, the optical and electro-optical components 2, 3, 5, 8 of the magnetic field sensor 1 are exposed to environmental conditions. This is problematic in particular for the excitation light source 3. If this is designed as a laser diode, the facet of the laser diode is sensitive to organic deposits.FIG. 2 shows a magnetic field sensor according to an embodiment of the invention. The resonator structure 8, the magneto-optical material 2, for example a diamond crystal with NV defects, the excitation light source 3, for example a laser diode, and a detector 5 are arranged on a base surface 14 of a housing 17. The housing 17 further has four side surfaces, of which two side surfaces 15, 16 are depicted in FIG. 2, and the base surface 14. The housing 17 can be formed in one piece and have a dielectric 7 at least on the base surface 14. The housing 17 can also consist completely or almost completely of a dielectric 7. The resonator structure 8 can be arranged directly on the base surface 14, in particular directly on the dielectric 7.A first metallic layer 10 can be arranged below the base surface 14 of the housing 17-and thus below the resonator structure 8-in particular parallel to the base surface 14. A second metallic layer 11 can be arranged above the resonator structure 8, in particular on a side of a ceiling surface 18 facing the components of the magnetic field sensor 2, 3, 5, 8. A microwave field 41 is formed which is shielded by the first and second metallic layers 10, 11 from an upper side 12 and a lower side 12 of a closed space 9 which is formed by the ceiling surface 18, the four side walls 15, 16 and the base surface 14. It is understood that only a single metallic layer (10, 27, 30) can also be arranged below the base surface 14 of the housing 17, wherein already by providing this one metallic layer sufficient shielding and shaping of the microwave field can be achieved.The cover surface 18 is formed on a cover 33, so that cover 33 and housing 17 close off the closed space 9 from the outside, in which the excitation light source 3, the detector 5, and the electromagnetic material 2 and the resonator structure 8 are arranged. In this way, the excitation light source 3 and the detector 5 are subject to environmental influences, such as, for example, ambient environment. This is protected against soiling. At the same time, the resonator structure 8 can thus be arranged in the immediate vicinity of the magneto-optical material 2, so that the microwave field generated by the resonator structure 8 can be transmitted into the magneto-optical material 2 without loss or with approximately no loss.The resonator structure 8 can also be surrounded-as shown in FIG. 2-by a third metallic layer 20 which is arranged on the base surface 14. The housing 17 can be arranged on a printed circuit board 24, in particular the housing 17 can be soldered onto the printed circuit board 24. A gap 25 is thereby formed between the printed circuit board 24 and the housing 17, and the gap 25 can be filled with air or filled with a preferably dielectric material. If the metallic layer 10 and 27 is absent, the thickness of the gap 25 between the housing 17 and the printed circuit board 24 influences the characteristic impedance of the resonator formed by the resonator structure 8, the dielectric 7 and the first and second metallic layers 11, 30, and also the propagation speed of the wave formed and thus the resonant frequency of the resonator. The provision of the third metallic layer 20 can reduce the sensitivity of the resonance frequency to variation in the thickness of the gap 25.Below the first metallic layer 10 or alternatively to the first metallic layer 10, one or more further metallic layers 27 can be provided in the housing 17, in particular parallel to the base surface 14 of the housing 17. The metallic layer(s) 27 may also be alternatively or additionally attached to an outer side of the housing 17. Likewise, further metallic layers 28, 29 can be arranged above the second metallic layer 11 or alternatively to the second metallic layer 11 in the cover 33, in particular parallel to the base surface 14 and / or to the cover surface 18, or on a side of the cover 33 facing away from the components of the sensor 2, 3, 5, 8, i.e. on an outer side of the cover 33.Metallic layers 30, 31, 32 can also be provided on the printed circuit board 24. These metallic layers 30, 32, 32 may be disposed on one or both sides and / or in the circuit board 24. The microwave source 4, which is connected to the resonator structure 8, and the magnetic field generating device 6 can also be arranged on the printed circuit board 24. The magnetic field generating device 6 can comprise a Helmholtz coil and / or one or more permanent magnets, which generate a permanent magnetic field in the region of the magneto-optical material 2.The metallic layers 10, 11, 27, 28, 29, 30, 31, 32 can be designed as ground planes, wherein they are connected to the electrical ground of the microwave source 4.FIG. 3 shows a further exemplary embodiment of the magnetic field sensor 1. unlike the exemplary embodiment from FIG. 2, the four side surfaces 15, 16 and the ceiling surface 18 of the enclosed space 9, in which the excitation light source 3, the detector 5, the magneto-optical material 2 and the resonator structure 8 are arranged, are formed on a closure 19. The base 14 is formed on a first dielectric substrate 21. The first dielectric substrate 21 comprises a dielectric 7. The shutter 19 is disposed directly on the first dielectric substrate 21. As in the exemplary embodiment according to FIG. 2, here too the excitation light source 3, the detector 5, the resonator structure 8, the magneto-optical material 2 and the third metallic layer 20 are arranged on the base surface 14. The third metallic layer 20 surrounds the resonator structure 8.The first metallic layer 10 may be disposed in the dielectric substrate 21. The second metallic layer 11 may be disposed on the ceiling surface 18 of the shutter 17 so as to face the components 2, 3, 5, 8 of the magnetic field sensor 1. Further metallic layers 28, 29 are arranged in or on the closure 17, for example parallel to the ceiling surface 18. The dielectric substrate 21 can be arranged on a printed circuit board 24--not shown in FIG. 3--analogously to the embodiment described in connection with FIG. 2.FIG. 4 shows a further embodiment of the magnetic field sensor 1 according to the invention. Herein, the first dielectric substrate 21 and a second dielectric substrate 22 are disposed in the case 17. In this case, the first metallic layer 10 is arranged on the base surface 14 of the housing 17 and the first dielectric substrate 21 is arranged on the first metallic layer 10. Resonator structure 8 and optionally also third metallic layer 20 are situated on first dielectric substrate 21.On the ceiling surface 18 of the cover 33, within the enclosed space 9, a fourth metallic layer 23 is arranged, on the side of which facing the enclosed space 9, the second dielectric substrate 22 is arranged. On the side of the second dielectric substrate 22 facing the closed space 9, the second metallic layer 11 is arranged. In this embodiment, the dielectric 7 is formed by the first dielectric substrate 21. The housing 17 can be arranged analogously to the embodiment described in connection with FIG. 2 on a printed circuit board 24-not shown in FIG. 4.FIG. 5 shows a further exemplary embodiment of the magnetic field sensor 1. as in the embodiment according to FIG. 2, the resonator structure 8, the excitation light source 3, the detector 5 and the magneto-optical material 2 are arranged on the base surface 14 of the housing 17. The third metallic layer 20 can likewise be arranged on the base surface 14 of the housing 17. The second metallic layer 11 is arranged on the ceiling surface 18 of the cover 33. The first metallic layer 10 is arranged below the base surface 14 in the housing 17, in particular parallel to the base surface 14, and is designed as a cooling block 25. The cooling block 25 may be formed of an electrically conductive material. The cooling block 25 can be connected to the electrical ground of the microwave source 4 and serve as a shield and / or as a ground plane. In this exemplary embodiment, too, the housing 17 can be arranged on a printed circuit board 24, which is not shown in FIG. 5, in a manner analogous to the embodiment described in connection with FIG. 2.FIG. 6 shows a further exemplary embodiment of the magnetic field sensor 1. the resonator structure 8, the excitation light source 3, the detector 5 and the magneto-optical material 2 are again arranged here on the base surface 14 of the housing 17. The third metallic layer 20 can likewise be arranged on the base surface 14 of the housing 17. The second metallic layer 11 is arranged in or on the cover 33, in particular parallel to the ceiling surface 18. The first metallic layer 10 is arranged below the base surface 14 in the housing 17, in particular parallel to the base surface 14. A fifth metallic layer 26 is arranged on at least one of the side surfaces 15, 16. Further metallic layers 34, 35 can be arranged in the housing 17 or the closure 19 or on an outer side of the housing 17 or the closure 19 in each case parallel to one of the side surfaces 15, 16. The metallic layers 26, 34, 35 further shield the microwave field from the surroundings of the magnetic field sensor 1. In this exemplary embodiment, too, the housing 17 can be arranged on a printed circuit board 24, which is not shown in FIG. 6, in a manner analogous to the embodiment described in connection with FIG. 2.FIG. 7 shows a further exemplary embodiment of the magnetic field sensor 1. the exemplary embodiment from FIG. 7 corresponds to the exemplary embodiment according to FIG. 6, wherein the metallic layers 26, 34, 35 arranged parallel to one of the side surfaces 15, 16 are connected to the metallic layers 10, 27 arranged on or in the housing 17 and / or to the metallic layers 11, 28, 29 arranged on or in the cover 33. The metallic layers 26, 34, 35 arranged parallel to one of the side surfaces 15, 16 can be conductively connected by contacts 36, 37, 38 to the metallic layers 11, 28, 29 running in or on the cover 33.It is understood that, even in an embodiment in which the side surfaces 15, 16 and the ceiling surface 17 are formed on a closure 19 and the base surface 14 is formed on a dielectric substrate 21, metallic layers 26, 34, 35 arranged parallel to one of the side surfaces 15, 16 can be provided-in this case in the closure 19. The metallic layers 26, 34, 35 arranged parallel to one of the side surfaces 15, 16 can also be electrically conductively connected to the metallic layers 10, 27 arranged in or on the dielectric substrate 21 and / or to the metallic layers 11, 28, 29 arranged in or on the closure 19 running parallel to the ceiling surface 18. In this case, the electrical connection of the metallic layers 10, 27 arranged in or on the dielectric substrate 21 to the metallic layers 26, 34, 35 arranged parallel to one of the side surfaces 15, 16 takes place via the contacts 36, 37, 38.FIG. 8 shows an embodiment of the magnetic field sensor 1 in a plan view. The resonator structure 8, the excitation light source 3 and the magneto-optical material 2 are arranged on the base surface 14 of the housing 17. The cover 33, which together with the housing 17 closes off the closed space from the outside, is not shown in FIG. 8. The resonator structure 8 has a horseshoe-shaped first part 39 and an annular second part 40, wherein both the horseshoe-shaped first part 39 and the annular second part 40 have a slot, at the respective edges of which the two parts 39, 40 are connected to one another. At the center of the ring-shaped second part 40, the magneto-optical material 2-in this case the diamond with NV defects-is arranged. The housing 17 is arranged on a printed circuit board 24. Also arranged on the printed circuit board 24 is the magnetic field generating device 6, which is formed as an arrangement of four permanent magnets.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2020 204 732

[0006]

Claims

Magnetic field sensor (1) having - a magneto-optical material (2), - an excitation light source (3) which is designed to emit excitation radiation for exciting electronic states of the magneto-optical material (2), - a microwave source (4) which is designed to generate an electromagnetic field for feeding a resonator structure (8), - a detector (5) which is designed to detect fluorescent radiation which the magneto-optical material (2) can emit as a result of irradiation with the excitation radiation, - a magnetic field generating device (6) which is arranged and designed to generate a permanent magnetic field in the region of the magneto-optical material (2), - a resonator structure (8) which is arranged on a dielectric (7) and is designed to shape the electromagnetic field emitted by the microwave source (4) such that a microwave field is produced, which is suitable for manipulating spin states of the magneto-optical material (2), - wherein the magneto-optical material (2), the excitation light source (3), the detector (5) and the microwave structure (8) are arranged in a closed space (9).Magnetic field sensor (1) according to Claim 1, wherein a first metallic layer (10) is arranged below the resonator structure (8) arranged on the dielectric (7) and / or a second metallic layer (11) is arranged above the resonator structure (8) arranged on the dielectric (7), and the first and / or second metallic layer (10, 11) are designed to shield the microwave field emerging from the microwave structure (8) from an upper side (12) and a lower side (13) of the closed space (9).Magnetic field sensor (1) according to Claim 1, wherein a base surface (14) and four side surfaces (15, 16) of the closed space (9) are formed on a housing (17), wherein the housing (17) has a dielectric (7) at least on the base surface (14).Magnetic field sensor (1) according to claim 1, wherein a ceiling surface (18) as well as the four side surfaces (15, 16) of the enclosed space (9) are formed on a shutter (19) and wherein the base surface (14) is formed on a first dielectric substrate (21).Magnetic field sensor (1) according to claim 2 or 3, wherein the resonator structure (8) is arranged on the base surface (14) of the enclosed space (9).Magnetic field sensor (1) according to one of the preceding claims, wherein the first and / or the second metallic layer (10, 11) are formed as ground plane which are connected to a ground of the microwave source (4).Magnetic field sensor (1) according to one of the preceding claims, wherein the resonator structure (8) is surrounded by a third metallic layer (20) likewise arranged on the dielectric (7).Magnetic field sensor (1) according to one of the preceding claims, wherein the resonator structure (8) is arranged opposite the first metallic layer (10) on the first dielectric substrate (21).Magnetic field sensor (1) according to one of the preceding claims, wherein the second metallic layer (11) is arranged on a second dielectric substrate (22).Magnetic field sensor (1) according to claim 8, wherein a fourth metallic layer (23) is arranged opposite the second metallic layer (11) on the second dielectric substrate (22).Magnetic field sensor (1) according to one of the preceding claims, wherein the housing (17) or the first dielectric substrate (21) is arranged on a printed circuit board (24).Magnetic field sensor (1) according to Claim 10, wherein a gap (25), in particular filled with air or a dielectric material, is arranged between the printed circuit board (24) and the housing (17) or the first dielectric substrate (21).Magnetic field sensor (1) according to one of the preceding claims, wherein the first metallic layer (10) is formed as a cooling block (25).Magnetic field sensor (1) according to one of the preceding claims, wherein a fifth metallic layer (26) is arranged parallel to one of the side surfaces (15, 16) of the enclosed space (9).Magnetic field sensor (1) according to claim 13, wherein the fifth metallic layer (26) electrically connects the first metallic layer (10) to the second metallic layer (11).

Images