CN113640715B - Solid-state spin magnetic sensor and magnetic field measurement method - Google Patents
Solid-state spin magnetic sensor and magnetic field measurement method Download PDFInfo
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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Abstract
The present disclosure provides a solid state spin magnetic sensor comprising: an optical unit for providing excitation light; a magnetic sensitive unit for converting part of the excitation light into a fluorescent signal; the magnetic sensitive unit is arranged between at least two oppositely arranged magnetic field gain units, and the magnetic field gain units are used for providing a bias magnetic field for the magnetic sensitive unit and amplifying the magnetic induction intensity of an external magnetic field to be detected; and the detection unit is used for detecting the fluorescent signal and the other part of the exciting light and carrying out digital conversion processing on the signal to obtain a digital signal, and the digital signal carries information of an external magnetic field to be detected. The disclosure also provides a magnetic field measurement method based on the solid-state spin magnetic sensor.
Description
Technical Field
The disclosure relates to the technical field of magnetic field measurement, in particular to a solid-state spin magnetic sensor and a magnetic field measurement method thereof.
Background
Among many quantum systems, solid state spin has been widely studied in recent years due to its ability to operate in a room temperature atmosphere and its high sensitivity. Meanwhile, the solid spinning system has great potential in the aspects of robustness and the like due to the structural stability of the physical carrier. The Nitrogen-Vacancy Center (NV Center) is a point defect in diamond, which belongs to one of the solid state spins and is the most widely studied one. NV color centers are used for magnetic measurement, and the prediction sensitivity can reach the Feitesla magnitude theoretically.
Most of the current magnetic measurement systems based on solid state spins such as NV color centers need to apply laser and microwave and detect the generated fluorescent signals. In recent years, a magnetic measurement method using no microwave in the NV color center system has appeared, which is called an all-optical magnetic measurement method. The method realizes the measurement of the magnetic field by utilizing the characteristic that the NV color center emits fluorescence with suddenly reduced intensity near the zero crossing point of the ground state energy level.
However, the existing all-optical magnetic measurement method needs to apply a bias magnetic field close to 1000 gauss, which is about 2000 times of the intensity of the geomagnetic field, and such a large bias magnetic field means that it needs a special electromagnet to generate, which is difficult to apply in most environments. At the same time, the instability of the bias field can also introduce new magnetic noise, which is a fatal problem for the magnetic measurement system.
In addition, the existing magnetic measurement system using the solid-state spin system, whether based on the all-optical method or the optical detection magnetic resonance method, requires high power consumption to meet the requirements of application of excitation light, microwaves and bias fields. This results in a limitation in the range of applications of the solid-state spin magnetic sensor, and new methods need to be considered to reduce the system power consumption.
Disclosure of Invention
In order to solve the above problems in the prior art, the present disclosure provides a solid state spin magnetic sensor and a magnetic field measurement method, which are intended to solve the application problem of an all-optical magnetometer in the prior art and solve the technical problem of large power consumption of a solid state spin magnetic sensor.
One aspect of the present disclosure provides a solid state spin magnetic sensor comprising: an optical unit for providing excitation light; a magnetic sensitive unit for converting part of the excitation light into a fluorescent signal; the magnetic sensing unit is arranged between at least two oppositely arranged magnetic field gain units, and the magnetic field gain units are used for providing a bias magnetic field for the magnetic sensing unit and amplifying the magnetic induction intensity of an external magnetic field to be detected; and the detection unit is used for detecting the fluorescent signal and the other part of the exciting light and carrying out digital conversion processing on the signal to obtain a digital signal, and the digital signal carries information of the external magnetic field to be detected.
Further, an excitation light modulation method or a magnetic field modulation method is adopted to modulate the external magnetic field to be measured to a high frequency, specifically: the optical unit is used for modulating the amplitude of the light source and outputting high-frequency exciting light to excite the solid spin of the magnetic sensitive unit; or a plurality of coils are arranged on the magnetic field gain unit to generate a periodic magnetic field superposed on the external magnetic field to be measured, so that the external magnetic field to be measured is modulated to high frequency.
Further, the magnetic sensitive unit is diamond containing nitrogen-hole defects, and a surface treatment structure formed by a metal film is arranged on the outer surface of the magnetic sensitive unit.
Further, the magnetic field gain unit is composed of a high magnetic permeability material, and the high magnetic permeability material is one or more of iron, cobalt, nickel, and ferrite.
Further, the magnetic field gain unit further comprises a magnet subunit for providing an additional bias magnetic field for the magnetically susceptible unit.
Further, the optical unit comprises one or more of a light collecting subunit or a light source subunit; the light collecting subunit is used for filtering and focusing natural light sources to obtain exciting light; the light source subunit comprises a current source and a light emitting diode or a current source and a laser diode, and is used for generating exciting light.
Furthermore, the detection unit comprises a light detection subunit and a data acquisition subunit; the optical detection subunit comprises a first photodetector and a second photodetector, the first photodetector is used for detecting a fluorescence signal and outputting a first electric signal, and the second photodetector is used for detecting another part of excitation light and outputting a second electric signal; and the data acquisition subunit is used for acquiring the first electric signal and the second electric signal and performing digital conversion processing to obtain a digital signal with a magnetic signal.
Further, the first and second photodetectors comprise one or more of photodiodes, filtering units, and amplifying units of at least two channels; the data acquisition subunit comprises one or more of an analog-to-digital converter, an auxiliary element and a main control core unit.
Further, the sensor further comprises: and the microwave subsystem is connected with the magnetic sensitive unit and is used for providing a microwave signal.
Another aspect of the present disclosure provides a magnetic field measurement method based on the solid-state spin magnetic sensor provided in the first aspect of the present disclosure, including: generating excitation light using an optical unit; converting part of the excitation light into a fluorescent signal through a magnetic sensitive unit; and converting the fluorescence signal and the other part of the exciting light into electric signals through a detection unit, and performing digital conversion processing to obtain digital signals, wherein the digital signals carry information of the external magnetic field to be detected.
Compared with the prior art, the method has the following beneficial effects:
(1) the structure is simplified: the present disclosure adopts a scheme of full light without microwave, does not need a microwave system, does not need a microwave signal generator and other devices for realizing modulation and demodulation, and greatly simplifies a structural device.
(2) And self-contained work: the exciting light required by the system can directly come from an ambient light source, and the required acquisition system adopts an extremely low power consumption design, is easy to combine with the existing energy collector, realizes the working under the condition of no artificial energy, and is easy to realize the sensor without the artificial energy.
(3) Low cost, low power consumption: the solid spin excitation device eliminates a microwave device required by a common solid spin magnetic measurement method by utilizing the optical characteristic of solid spin, does not need to adopt a high-cost coherent laser source to realize the excitation of the solid spin, adopts a natural light source or a low-cost low-power consumption device, and has low cost and low maintenance cost.
(4) And the sensitivity is high: the sensitivity and the anti-interference capability of the sensor are improved by adopting the magnetic field gain unit and a method of exciting light modulation or magnetic field modulation.
(5) And the method is easy to apply: by the method of amplifying the magnetic flux gathering bias field, the solid state spin can be positioned on a ground state level crossing-free working point (GSLAC) without using a strong bias field (electromagnet and the like), and application difficulty caused by manually applying the strong bias field is avoided.
Drawings
For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
FIG. 1 schematically illustrates a block diagram of a solid state spin magnetic sensor according to one embodiment of the present disclosure;
FIG. 2 is a schematic diagram showing fluorescence versus magnetic field for a solid state spin magnetic sensor according to one embodiment of the present disclosure;
FIG. 3 schematically illustrates a magnetic gain diagram for a solid state spin magnetic sensor according to an embodiment of the disclosure;
FIG. 4 schematically illustrates a block diagram of a solid state spin magnetic sensor according to another embodiment of the disclosure;
fig. 5 schematically shows a flowchart of a magnetic field measurement method based on a solid-state spin magnetic sensor according to an embodiment of the present disclosure.
Detailed Description
Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is illustrative only and is not intended to limit the scope of the present disclosure. In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present disclosure.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The terms "comprises," "comprising," and the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.
All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. It is noted that the terms used herein should be interpreted as having a meaning that is consistent with the context of this specification and should not be interpreted in an idealized or overly formal sense.
The existing precise magnetism measuring technology based on the NV color center polarizes the NV color center mainly based on exciting light, controls the NV color center by using a microwave field, and obtains the population degree of the NV color center spinning quantum state by reading the intensity change of a fluorescence signal generated by the NV color center, so that the intensity of an external magnetic field can be obtained. The present disclosure combines a magnetic flux gathering method or an environmental energy collection method based on the response characteristics of fluorescence generated by solid spin represented by NV color center to a magnetic field to realize the measurement of the solid spin to an external magnetic field with low power consumption even without artificial energy.
Embodiments of the present disclosure provide a solid state spin magnetic sensor, comprising: an optical unit for providing a light source; the magnetic sensitive unit is used for converting part of the light source into a fluorescent signal; the magnetic sensitive unit is arranged between at least two oppositely arranged magnetic field gain units, and the magnetic field gain units are used for providing a bias magnetic field for the magnetic sensitive unit and amplifying the magnetic induction intensity of an external magnetic field to be detected; and the detection unit is used for detecting the fluorescent signal and the other part of the light source and carrying out digital conversion processing on the signal to obtain a digital signal, and the digital signal carries the information of the external magnetic field to be detected.
The embodiment of the disclosure provides a solid spin magnetic sensor, which can realize measurement of variation of an external magnetic field by using the optical response characteristic of solid spin in diamond to the external magnetic field without adopting any microwave device; the optical unit can realize the optical excitation of the solid spin of the magnetic sensitive unit by collecting natural light sources or adopting a low-cost low-power consumption artificial light source; the magnetic field gain unit provides a proper bias field for the magnetic sensitive unit, and simultaneously, the sensitivity is improved by amplifying the magnetic field to be detected; when the solid state spinning is excited by the collected natural light source, in order to realize the self-contained type sensor without artificial energy supply, the detection unit adopts a small natural energy generator to supply energy. The solid-state spin magnetic sensor can effectively improve the sensitivity and the anti-interference capability of the sensor through an excitation light modulation method or a magnetic field modulation method. The solid-state spin magnetic sensor provided by the embodiment of the disclosure realizes a novel composite all-optical magnetic measurement method with high sensitivity, high integration and low power consumption under all-optical conditions, and a magnetic sensor.
The following describes the technical solution of the present disclosure in detail with reference to the structure of the solid-state spin magnetic sensor in the specific embodiment of the present disclosure. It should be understood that the structure of the solid-state spin magnetic sensor shown in fig. 1 is merely exemplary to help those skilled in the art understand the technical solution of the present disclosure, and is not intended to limit the scope of the present disclosure.
Fig. 1 schematically illustrates a structural schematic of a solid state spin magnetic sensor according to an embodiment of the present disclosure. The embodiment provides a solid-state spin magnetic sensor which is powered by an environmental energy source and combined with a magnetic flux concentrator based on the optical response principle of an NV color center to a magnetic field.
As shown in fig. 1, the solid-state spin magnetic sensor includes:
an optical unit 10 for providing excitation light.
According to an embodiment of the present disclosure, the optical unit 10 includes one or more of a light collecting subunit or a light source subunit. In this embodiment, taking the optical unit 10 as an example including a light collecting subunit, as shown in fig. 1, the light collecting subunit includes one or more of a lens, a parabolic condenser, a filter, a concave mirror, and a plane mirror, and the light collecting subunit is configured to perform filtering and focusing on a natural light source to obtain excitation light, for example, the light collecting subunit may include a filter 110 and a lens 120, where a specific wavelength component is retained after the natural light source such as sunlight passes through the filter 110, and a part of the light source is focused through the lens 120 and then irradiates the magnetic sensitive unit 20.
A magnetically susceptible unit 20 for converting part of the excitation light into a fluorescent signal. The magnetic sensing unit 20 is disposed between at least two oppositely disposed magnetic field gain units 30, and the magnetic field gain units 30 are configured to provide a bias magnetic field for the magnetic sensing unit 20 and amplify magnetic induction intensity of an external magnetic field to be measured. The fluorescence signal output by the magnetic sensing unit 20 carries information such as the frequency and magnetic induction intensity of the external magnetic field to be measured.
In the embodiment of the present disclosure, the excitation light focused by the lens 120 is irradiated onto the magnetic sensing unit 20 to generate a fluorescence signal. Wherein, the magnetic sensitive unit 20 is a diamond with NV color center (nitrogen-hole defect), the diamond sample can be in any crystal orientation, and the NV color center is composed of the nitrogen defect and the adjacent hole. The NV color center unpaired electron constitutes a spin triplet-singlet system whose triplet ground state 3 E and the first excited state 3 The energy difference between A is 1.945eV, corresponding to a zero phonon line of 637 nm. Therefore, when a beam of excitation light with energy greater than or equal to 1.945eV is used for exciting the NV color center, electrons of the NV color center are excited to an excited state, and then the electrons are excited back to a ground state with a great probability, so that fluorescence photons are emitted to form fluorescence. When the electron spin is in excited state m s At an energy level of + -1, the electron will have a greater probability of relaxing to m of the ground state through a singlet state s No photons are emitted at the 0 level. In the absence of an external magnetic field, the process of radiation transition keeps the spin state unchanged, in the presence of a transverse magnetic field, the spin states are overlapped, the spin states have higher probability of returning to the ground state through non-radiation transition, and the fluorescence intensity is reduced, so that the magnitude of the external magnetic field can be quantitatively measured through the magnitude of the fluorescence reduction, and for the case that the external magnetic field is along the diamond crystal direction, the change of the fluorescence along with the external magnetic field is shown in fig. 2. It is known that the relative fluorescence intensity decreases as the intensity of the external magnetic field increases.
Preferably, a surface treatment structure may be added to the magnetically sensitive unit 20 by a plating process, and the surface treatment structure may be a metal film, such as a gold film, a silver film, an aluminum film, and the like, and may further be combined with a protective film of silicon monoxide, magnesium fluoride, silicon dioxide, aluminum oxide, and the like to further protect the stability of the surface treatment structure.
The magnetic field gain unit 30 is formed in a specific shape, such as a trapezoidal shape, a cylindrical shape, a long bar shape, etc., and is made of a material having a high magnetic permeability, which is one or more of iron, cobalt, nickel, and ferrite. The magnetically susceptible unit 20 is located in the center of a plurality of oppositely disposed magnetic field gain units 30. When the magnetic field is in the magnetic field, the magnetic field at the magnetic sensitive unit is larger than the magnetic field when the gain unit is not present, the gain coefficient is G, and different amplification factors can be obtained by adjusting the direction (i.e. the included angle θ) of the magnetic field gain unit 30 and the ambient magnetic field, as shown in fig. 3, so that the amplification of the external magnetic field to be measured and the provision of a required proper bias field for the solid spin system can be realized. Fig. 3b is an enlarged view of a portion a in fig. 3 a.
And the detection unit 40 is configured to detect the fluorescent signal and another part of the excitation light, and perform digital conversion on the signal to obtain a digital signal, where the digital signal carries information of the external magnetic field to be detected, and the information at least includes information such as frequency of the external magnetic field to be detected and magnetic induction intensity. Wherein another part of the light sources provides background field information of the excitation light in the detection unit 40 for correcting the influence due to the variation of the intensity of the excitation light in the magnetic field measurement.
In this embodiment, the detection unit 40 includes a light detection subunit 410 and a data acquisition subunit 420. The light detection subunit 410 includes a first photodetector 411 and a second photodetector 412, where the first photodetector 411 is configured to detect the fluorescent signal and output a first electrical signal, and the second photodetector 412 is configured to detect another part of the light sources and output a second electrical signal. And the data acquisition subunit 420 is configured to acquire the first electrical signal and the second electrical signal and perform digital conversion processing to obtain a digital signal with a magnetic signal.
Specifically, the first and second photo detectors 411 and 412 include one or more of photodiodes, filtering units, and amplifying units of at least two channels. The data collecting subunit 420 includes one or more of an analog-to-digital converter, an auxiliary component, and a main control core unit, wherein the main control core unit is used for further processing (such as magnetic field correction, noise reduction, signal conversion, etc.), transmission, storage control, etc. of data, and the analog-to-digital converter can be combined with the auxiliary component to collect the electrical signal output by the optical detecting subunit 410 and perform digital conversion processing on the electrical signal. For example, the first light detector 411 and the second light detector 412 are photodiodes, wherein the photodiodes are in a photovoltaic mode, and can directly convert the fluorescence signal into an electrical signal without external energy. Due to the low power consumed by the photodiode, when detecting high-frequency high-light-intensity signals, the bias voltage can be provided by the small solar panel. The data acquisition subunit 420 is a low power consumption data acquisition card, and the energy required by the data acquisition card is provided by a small-sized solar cell panel/wind generator in watt level.
According to an embodiment of the present disclosure, the magnetic field gain unit 30 may further include a magnet subunit for providing an additional bias magnetic field to the magneto-sensitive unit 20 when the ambient magnetic field is insufficient to provide a suitable bias field for the sensor to operate and optimize.
In this embodiment, a magnetic field modulation method is adopted to modulate the external magnetic field to be measured to a high frequency, so as to avoid low-frequency noise of the system, specifically, a plurality of coils are arranged on the magnetic field gain unit 30 to generate a periodic magnetic field superimposed on the external magnetic field to be measured, so as to modulate the external magnetic field to be measured to a high frequency. If the driver can generate 1 KHz-1 MHz sine wave or square wave signal to drive the coil on the magnetic field gain unit 30 to generate an artificial magnetic field with specific frequency, at this time, when the external magnetic field to be measured changes, the external magnetic field to be measured can be mixed with the artificial magnetic field, and the extraction of the external magnetic field information can be completed through the phase-locked amplifier and other demodulation devices.
Compared with other types of diamond magnetometer probes, the solid-state spin magnetic sensor provided by the embodiment has the advantages of high integration level, high stability, low cost and the like.
It should be noted that the above-mentioned component structures are only exemplary, and do not represent that the component structures cannot be replaced in other practical applications, and do not constitute a limitation on the solid-state spin magnetic sensor structure provided by the present disclosure. In addition, the high frequency ranges of the embodiments of the disclosure are all 1KHz to 1 MHz.
Fig. 4 schematically illustrates a structural schematic of a solid state spin magnetic sensor according to another embodiment of the present disclosure.
As shown in fig. 4, the solid-state spin magnetic sensor differs from the solid-state spin magnetic sensor provided in the previous embodiment in that:
in the present embodiment, the optical unit 10 includes: a light source subunit comprising a combination of a current source 110 'and a light emitting diode 120' or a combination of a current source and a laser diode, the light source subunit being for generating excitation light. The light detection subunit 410 'includes a filter 411' and a photodiode 412 ', and the data acquisition subunit 420' is an analog-to-digital converter. The sensor further comprises a current source control unit 50, the current source control unit 50 being adapted to control an operating parameter of the current source 110', such as the frequency of the generated current or a sine wave signal or a square wave signal.
Specifically, the magnetic sensing unit 20 is a diamond containing a nitrogen-vacancy color center, and is disposed at the center of a plurality of magnetic field gain units 30 (i.e., concentrators) designed by a special structure (such as a trapezoid, a cylinder, a strip, etc.), and the crystal orientation of the magnetic sensing unit 20 is disposed along the symmetry axis of the magnetic field gain units 30, when the main axis of the NV color center is not parallel to the external magnetic field, the change of the external magnetic field will cause the lateral field sensed by the NV color center to change, and the lateral field will change the intensity of the fluorescent signal generated by the excited NV color center. It should be noted that there are 4 principal axes of NV colour centers in a diamond, so any external magnetic field will contribute transverse magnetic field components to several of these principal axes. The magnetic field gain unit 30 amplifies an external magnetic field and then acts on the magnetic sensitive unit 20 by adjusting an included angle (see fig. 3a) between the axial direction of the magnetic field gain unit 30 and a geomagnetic field or an additional magnet subunit to provide a bias field with a specific size for the magnetic sensitive unit 20, so that the magnetic sensitive unit 20 can be provided with the bias field only by using the geomagnetic field, and the NV color center in the magnetic sensitive unit reaches an energy level non-crossing state.
In this embodiment, taking the light source subunit formed by the combination of the current source 110 'and the light emitting diode 120' as an example, the light source subunit adopts an excitation light modulation method to modulate the external magnetic field to be measured to a high frequency, so as to avoid the low-frequency noise of the system, specifically: the light source is amplitude modulated by the optical unit 10, and high frequency excitation light is output to excite the solid state spins of the magneto-sensitive unit 20. As shown in fig. 4, the current source 110 ' generates a 1KHz to 1MHz sine wave or square wave current to the light emitting diode 120 ' (or laser diode), and drives the light emitting diode 120 ' to emit a green laser with a specific wavelength in a wave band of 510 to 550nm onto the magnetic sensitive unit 20, so that the NV color center electrons in the magnetic sensitive unit 20 are spin-transitioned to an excited state, and a fluorescent signal is emitted in a process of being deexcited. After a magnetic field to be measured is applied, under the control of laser, the magnetic sensing unit 20 emits a fluorescent signal containing information of the magnetic field to be measured, the fluorescent signal irradiates the photodiode 412 ' through the optical filter 411 ' and is converted into an electric signal, and the electric signal is collected by the data collecting subunit 420 ' through a cable, so that one-time magnetic signal measurement is completed.
The embodiment has low power consumption, so that the power can be supplied by an upper computer or a battery, and compared with other types of diamond magnetometers and the embodiment, the power-saving diamond magnetometer has the advantages of low power consumption, all-weather operation and high sensitivity. In addition, the collected digital signals carrying the information of the external magnetic field to be detected can be further processed by an upper computer, for example, the digital signals are converted into magnetic field signals by using conversion coefficients calibrated in a laboratory, so that the visual information of the external magnetic field to be detected is obtained.
In this embodiment, the magnetic field gain unit 30 may further include a magnet subunit for providing an additional bias magnetic field to the magneto-sensitive unit 20 when the ambient magnetic field is not sufficient to provide a suitable bias field for the sensor to operate and optimize.
In yet another embodiment of the present disclosure, the optical unit is comprised of a driver and an LD/LED that generates an outgoing optical signal to excite the magnetically susceptible unit. Preferably, the direction in which the diamond sample is clamped by the magnetic field gain unit is a crystal direction, and the magnitude of the bias field provided to the magnetic sensitive unit is about 1024 gauss. The detection unit is a photodiode and converts the fluorescent signal generated by the magnetic sensitive unit into an electric signal. The embodiment on one hand adopts the concentrator to avoid the noise introduced by an extra large bias field, and can use a weak bias field or a geomagnetic field to provide a required bias field; and on the other hand, the NV color center is in an energy level non-crossing state, and high-sensitivity magnetic field measurement is realized. Under the condition that a bias field is kept unchanged, a fluorescence signal generated by exciting a magnetic sensitive unit by an optical unit emergent light signal consisting of a driver and an LD/LED changes along with the change of a magnetic field to be measured, and the fluorescence signal related to the external magnetic field to be measured is converted into an electric signal by a detection unit to realize the measurement of the external magnetic field to be measured.
In some other practical embodiments, the solid state spin magnetic sensor further comprises: a microwave subsystem, connected to the magneto-sensitive unit 20, for providing a microwave signal in order to further improve the sensitivity of the sensor.
It should be noted that the above definitions of the components and the preferred design method of the solid-state spin magnetic sensor are not limited to those shown in the above embodiments, and those skilled in the art can apply them to the solid-state spin magnetic sensor with higher frequency and higher wavelength band by equivalent replacement or structural modification.
FIG. 5 schematically illustrates a flow chart of a magnetic field measurement method of an embodiment of the present disclosure, the method steps employing a solid state spin magnetic sensor as shown in FIG. 1 or FIG. 4.
As shown in fig. 5, the magnetic field measuring method includes:
s501, excitation light is generated by an optical unit.
The excitation light is generated by the optical unit through an artificial or natural green light waveband low-cost light source and used for realizing the excitation of the solid spin of the magnetic sensitive unit, and the intensity of the emitted fluorescence changes along with the change of an external magnetic field due to the energy level structure characteristics of the solid spin, so that the measurement of the external magnetic field to be measured is realized.
And S502, converting part of the excitation light into a fluorescence signal through the magnetic sensitive unit.
The excitation light generated in step S501 causes the spin of electrons in the magnetic sensitive cell to transit between the ground state and the excited state, and emits a fluorescent signal whose intensity is related to the spin population of the system. And the magnetic sensitive unit is arranged in an external magnetic field to be measured, and the bias field and the exciting light intensity are kept unchanged. Preferably, the magnitude of the bias field applied to the solid state spins of the magneto-sensitive cells is between 200-700 gauss or around 1024 gauss.
And S503, converting the fluorescence signal and the other part of the exciting light into electric signals through the detection unit, and performing digital conversion processing to obtain digital signals, wherein the digital signals carry information of the external magnetic field to be detected.
The sensor structure for measuring the magnetic field by the solid-state spin magnetic sensor used in this embodiment is shown in fig. 1 or fig. 4, and details thereof are not repeated here.
The solid-state spin magnetic sensor provided by the embodiment of the disclosure has the following characteristics: 1) the novel composite all-optical magnetic measurement scheme and the magnetic sensor with high sensitivity, high integration and low power consumption under the all-optical condition are realized by combining the magnetic flux gathering method based on the magnetic sensitive optical characteristic of solid state spinning; 2) the solid spin can be positioned on a ground state energy level crossing-free working point (GSLAC) without using a strong bias field (electromagnet and the like) through the amplification of the bias field of magnetic flux collection, so that the application difficulty caused by manually applying the strong bias field is avoided; 3) by utilizing ambient light, such as sunlight and similar artificial illumination light, a power consumption-free sensor which completely depends on environmental energy can be realized; 4) and the sensitivity and the anti-interference capability of the sensor are improved by a method of exciting light modulation or magnetic field modulation.
While the present disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive, and fig. 1 or 4 show schematic structural views of solid state spin magnetic sensors according to embodiments of the present disclosure, in which certain components may be replaced with other components having the same or similar functions or experimental principle device structures may be more simplified or complicated in practical applications, and this embodiment does not constitute a limitation of the solid state spin magnetic sensors.
Those skilled in the art will appreciate that various combinations and/or combinations of features recited in the various embodiments and/or claims of the disclosure can be made to the extent not expressly recited in the disclosure. In particular, various combinations and/or combinations of the features recited in the various embodiments and/or claims of the present disclosure may be made without departing from the spirit or teaching of the present disclosure. All such combinations and/or associations are within the scope of the present disclosure.
While the disclosure has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure as defined by the appended claims and their equivalents. Accordingly, the scope of the present disclosure should not be limited to the above-described embodiments, but should be defined not only by the appended claims, but also by equivalents thereof.
Claims (10)
1. A solid state spin magnetic sensor, comprising:
an optical unit (10) for providing excitation light;
a magnetically sensitive unit (20) for converting part of the excitation light into a fluorescent signal; the magnetic sensitive unit (20) is arranged between at least two oppositely arranged magnetic field gain units (30), and the magnetic field gain units (30) are used for providing bias magnetic fields for the magnetic sensitive unit (20) and amplifying the magnetic induction intensity of an external magnetic field to be detected;
and the detection unit (40) is used for detecting the fluorescent signal and the other part of the exciting light and carrying out digital conversion processing on the signal to obtain a digital signal, and the digital signal carries the information of the external magnetic field to be detected.
2. The solid-state spin magnetic sensor of claim 1, wherein an excitation light modulation method or a magnetic field modulation method is used to modulate the external magnetic field to be measured to a high frequency, specifically:
the exciting light is subjected to amplitude modulation through the optical unit (10), and high-frequency exciting light is output to excite the solid-state spin of the magnetic sensitive unit (20); or
And a plurality of coils are arranged on the magnetic field gain unit (30) to generate a periodic magnetic field superposed on the external magnetic field to be measured so as to modulate the external magnetic field to be measured to high frequency.
3. The solid state spin magnetic sensor of claim 1, wherein the magnetically susceptible unit (20) is diamond containing nitrogen-hole defects, and the outer surface of the magnetically susceptible unit (20) is provided with a surface treatment structure formed of a metal film.
4. The solid state spin magnetic sensor of claim 1, wherein the magnetic field gain cell (30) is constructed of a high permeability material that is one or more of iron, cobalt, nickel, and ferrite.
5. The solid state spin magnetic sensor of claim 1, wherein the magnetic field gain cell (30) further comprises a magnet subunit for providing an additional bias magnetic field for the magnetically sensitive cell (20).
6. The solid state spin magnetic sensor of claim 1, wherein the optical unit (10) comprises one or more of a light collecting subunit or a light source subunit; wherein the content of the first and second substances,
the light collecting subunit comprises one or more of a lens, a paraboloid condenser, a light filter, a concave mirror and a plane mirror, and is used for filtering and focusing natural light sources to obtain exciting light;
the light source subunit comprises a current source and a light emitting diode or a current source and a laser diode, and is used for generating exciting light.
7. The solid state spin magnetic sensor of claim 1, wherein the detection unit (40) comprises a light detection subunit and a data acquisition subunit; wherein, the first and the second end of the pipe are connected with each other,
the optical detection subunit comprises a first photoelectric detector and a second photoelectric detector, wherein the first photoelectric detector is used for detecting the fluorescence signal and outputting a first electric signal, and the second photoelectric detector is used for detecting the other part of the excitation light and outputting a second electric signal;
and the data acquisition subunit is used for acquiring the first electric signal and the second electric signal and performing digital conversion processing to obtain a digital signal with a magnetic signal.
8. The solid state spin magnetic sensor of claim 7,
the first photoelectric detector and the second photoelectric detector comprise one or more of photodiodes, filtering units and amplifying units of at least two channels;
the data acquisition subunit comprises one or more of an analog-to-digital converter, an auxiliary element and a main control core unit.
9. A solid state spin magnetic sensor according to claim 1, further comprising:
a microwave subsystem connected to the magnetically susceptible unit (20) for providing a microwave signal.
10. A magnetic field measurement method based on the solid-state spin magnetic sensor according to any one of claims 1 to 9, comprising:
generating excitation light using an optical unit;
converting part of the excitation light into a fluorescent signal through a magnetic sensitive unit;
and converting the fluorescence signal and the other part of the exciting light into electric signals through a detection unit, and performing digital conversion processing to obtain digital signals, wherein the digital signals carry information of the external magnetic field to be detected.
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