Alternating magnetic field sensitive detection device and method based on resonant cavity-magnetor coupling system sideband regulation and control

Abstract

The invention relates to an alternating magnetic field sensitive detection device and method based on resonant cavity-magnetic vibrator coupling system sideband regulation and control. The device comprises a microwave source, a superconducting resonant cavity, a YIG small ball, a filter, two signal amplifiers, a rectifier diode, a permanent magnet and a signal reading system. According to the invention, signal amplification of an alternating magnetic field is realized through the resonant cavity-magnetic vibrator coupling system; sensitive detection of the alternating magnetic field is achieved, and the detection sensitivity reaches pT / Hz. A coupling system formed by a resonant cavity and a magnetic material is utilized to develop a weak magnetic field sensitive detection device and method which can be operated at liquid nitrogen temperature or room temperature and have irrelevant sensitivity and size.

Description

Technical Field

[0001] The invention relates to an alternating magnetic field sensitive detection device and method based on sideband regulation of a resonant cavity-magnon coupling system, belonging to the technical field of magnetic field detection. Background Art

[0002] At present, magnetometers for detecting weak magnetic fields have been widely used, from condensed matter experiments, gravitational wave detection to nuclear magnetic resonance signal detection, paleomagnetic research, non-destructive testing and underwater object detection. Mature magnetometers include fluxgate magnetometers, superconducting quantum interferometers, diamond color center magnetometers and atomic magnetometers. These magnetometers are limited by their working principles and are suitable for different scenarios.

[0003] At present, the most sensitive magnetic field detectors are atomic magnetometers developed based on the spin exchange relaxation-free (SERF) state of alkali metal atomic vapor and low-temperature superconducting quantum interference devices (SQUIDs) developed based on Josephson junctions. Their detection sensitivity can reach below fT / √Hz, so they play an important role in ultra-high precision magnetic field measurements. The SERF state is a special state of alkali metal atomic vapor. It refers to a magnetic resonance with extremely low line width formed in alkali metal atomic vapor when the spin exchange rate between alkali metal atoms is much larger than the Larmor precession frequency. There are two core parameters that determine the detection sensitivity of the SERF magnetometer: one is that the resonance line width of the SERF state is only 200Hz, and the other is that the rate of change of the SERF state frequency with the external magnetic field is 28GHz / T. The former reflects the limit resolution of the SERF state in the spectrum, while the latter reflects the response of the SERF state to changes in the external magnetic field. One is determined by the intrinsic properties of the SERF state, and the other is determined by the electron charge-to-mass ratio, and both are difficult to be further optimized. SQUIDs require cryogenic operation, while SERF magnetometers do not, and their sensitivity is related to their size. Summary of the invention

[0004] In view of the current status of sensitive magnetic detection technology, the present invention uses a coupling system composed of a resonant cavity and a magnetic material to develop a weak magnetic field sensitive detection device and method that can operate at liquid nitrogen temperature or room temperature and has sensitivity independent of size.

[0005] The main technical problems solved by the present invention include: first, realizing signal amplification of the alternating magnetic field through the resonant cavity-magnon coupling system; second, realizing sensitive detection of the alternating magnetic field, and the detection sensitivity reaches pT / √Hz.

[0006] Terminology explanation:

[0007] HackRFOne, a handheld microwave receiving and transmitting device with spectrum analysis capabilities, is mostly used by radio enthusiasts.

[0008] The technical solution of the present invention is:

[0009] An alternating magnetic field sensitive detection device based on sideband regulation of a resonant cavity-magnon coupling system, comprising:

[0010] Microwave source, superconducting resonant cavity, YIG sphere, filter, two signal amplifiers, rectifier diodes, permanent magnet and signal readout system;

[0011] The resonant cavity-magnon coupling system includes a superconducting resonant cavity and a YIG ball, and the YIG ball is placed in the center of the superconducting resonant cavity; the microwave source generates monochromatic microwaves to drive the superconducting resonant cavity and the YIG ball, and after being modulated by the alternating magnetic field to be measured, the output signal passes through a filter, two signal amplifiers, a rectifier diode, and is finally measured by a voltmeter;

[0012] The superconducting resonant cavity converts the magnitude of the alternating magnetic field into the intensity of the sideband signal through coupling with the magnetic material;

[0013] Magnetic vibrators, or YIG balls, are used to sense alternating magnetic fields. When the alternating magnetic field acts on the YIG balls, the microwave-driven resonant cavity-magnetic vibrator coupling system generates sideband signals through coupling. By measuring the intensity of the sideband signals, the magnitude of the alternating magnetic field can be deduced.

[0014] The filter filters out microwaves other than the signal to be measured and transmits monochromatic microwaves;

[0015] The signal amplifier amplifies the output signal to improve the signal-to-noise ratio;

[0016] The rectifier diode rectifies the output signal, and the voltage signal measured by the voltmeter reflects the size of the alternating magnetic field;

[0017] The permanent magnet provides a bias magnetic field to the YIG ball, causing the YIG ball to precess at a certain frequency.

[0018] The signal readout system is used to detect the strength of the sideband signal.

[0019] Preferably, according to the present invention, the superconducting resonant cavity is any one of a microstrip line resonator (Stripline Resonator), a split ring resonator (Split Ring Resonator), a dielectric resonator (Dielectric Resonator), and a microwave resonant cavity (Microwave Cavity).

[0020] Preferably according to the present invention, the magnetic material is any one of yttrium iron garnet, iron oxide, permalloy and cobalt zirconium alloy; the magnetic material generates ferromagnetic resonance under microwave driving.

[0021] More preferably, the bias magnetic field is any one of a neodymium iron boron magnet, a ferrite magnet, and an electromagnetic coil.

[0022] Preferably according to the present invention, the signal readout system is any one of a vector network analyzer, a signal analyzer, a HackRFOne, an oscilloscope, and a nanovoltmeter.

[0023] According to the preferred embodiment of the present invention, the signal amplifier is a low noise high electron mobility transistor (HEMTs), and the gain G 1 and gain G 2 All are 0-25dB;

[0024] Further preferably, the gain G 1 and gain G 2 Both are 25dB.

[0025] A method for sensitively detecting an alternating magnetic field based on sideband regulation of a resonant cavity-magnon coupling system is implemented by the above-mentioned device for sensitively detecting an alternating magnetic field, comprising:

[0026] A magnon, i.e. a YIG ball, is inserted into a superconducting resonant cavity to form a resonant cavity-magnon coupling system. A microwave source generates monochromatic microwaves to drive the resonant cavity-magnon coupling system. The microwaves radiated by the resonant cavity-magnon coupling system are filtered by a filter, and then amplified by two signal amplifiers. After being rectified by a rectifier diode, the voltage signal measured by a voltmeter reflects the size of the alternating magnetic field.

[0027] Preferably, according to the present invention, a yttrium iron garnet (YIG) sphere is placed in the center of the yttrium barium copper oxide superconducting resonant cavity to form a resonant cavity-magnon coupling system; the bias magnetic field adjusts the Larmor frequency of electrons in the yttrium iron garnet (YIG) sphere to the cavity mode frequency, and couples the magnon mode with the resonant cavity mode;

[0028] Further preferably, when the magnetic oscillator is coupled with the resonant cavity, the cavity mode is split into two hybrid modes;

[0029] The permanent magnet provides an external magnetic field B. When an alternating magnetic field b provided by an alternating signal and parallel to the external magnetic field B is added 1 , and when the driving microwave applies a monochromatic microwave to any of the two mixed modes, the frequency is ω b The alternating magnetic field b 1 Will produce a pair ω i Frequency modulation, i = 1, 2, at frequency ω i +nω b Sidebands are generated at 1 +nω b =ω 2For weak magnetic fields, only the sideband corresponding to n = 1 has a significant amplitude, and for frequency ω b =2g 21 The detection of alternating magnetic fields is more sensitive. The filter then filters out microwaves other than the signal to be measured. After amplification and rectification, the intensity of the sideband signal is positively correlated with the size of the alternating magnetic field. The voltage signal measured by the voltmeter reflects the size of the alternating magnetic field.

[0030] The beneficial effects of the present invention are:

[0031] 1. Ultra-high sensitivity: The present invention realizes the amplification of weak alternating magnetic field signals. Through the resonant cavity-magneton coupling system and the suppression of other sideband signals by the filter, the magnetometer realizes sensitive detection of alternating magnetic fields with a detection sensitivity of 5pT / √Hz.

[0032] 2. Low cost: The superconducting resonant cavity, filter, signal amplifier, and magnetic material used in the present invention are all mature commercial products and do not require additional research and development.

[0033] 3. Easy integration: The superconducting resonant cavity and filter used in the present invention can be planar microwave devices. These planar structures can be reduced to micrometer size using micro-nano processing technology. In addition, since the sensitivity of the device does not depend on its size, a smaller PMHS can be designed.

[0034] 4. Simple structure: The present invention does not require a complex optical path, and the detection signal can be read out electrically. In addition, the present invention can work at (normal temperature) without the need for additional heating or cooling devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a structural schematic diagram of a magnetic field sensitive detection device based on a superconducting resonant cavity-magnon coupling system of the present invention;

[0036] Figure 2 Schematic diagram of the transmission of the resonant cavity-magnon coupling system and the filter changing with frequency;

[0037] Figure 3 Schematic diagram of signal spectrum under alternating magnetic fields of different sizes;

[0038] Figure 4 Schematic diagram of the change of alternating magnetic field with different voltage signals. DETAILED DESCRIPTION

[0039] The present invention will be further defined below in conjunction with the accompanying drawings and embodiments, but is not limited thereto.

[0040] Example 1

[0041] A sensitive detection device for alternating magnetic fields based on sideband regulation of a resonant cavity-magnon coupling system, such as Figure 1 As shown, including:

[0042] Microwave source, superconducting resonant cavity, YIG sphere, filter, two signal amplifiers, rectifier diodes, permanent magnet and signal readout system;

[0043] The resonant cavity-magnon coupling system includes a superconducting resonant cavity and a YIG ball, which is placed at the center of the superconducting resonant cavity. Since both generate radiated microwaves, the YIG ball and the superconducting resonant cavity interact with each other. At this time, the system will have two eigenmodes, and their frequencies will show anti-crossing curves as the magnetic field changes.

[0044] The microwave source generates monochromatic microwaves to drive the superconducting resonant cavity and the YIG ball. After being modulated by the alternating magnetic field to be measured, the output signal passes through a filter, two signal amplifiers, a rectifier diode, and is finally measured by a voltmeter.

[0045] The superconducting resonant cavity converts the magnitude of the alternating magnetic field into the strength of the sideband signal through coupling with the magnetic material; it plays the role of information conversion in the entire measuring device;

[0046] Magnetic vibrators, or YIG balls, are used to sense alternating magnetic fields. When the alternating magnetic field acts on the YIG balls, the microwave-driven resonant cavity-magnetic vibrator coupling system generates sideband signals through coupling. By measuring the intensity of the sideband signals, the magnitude of the alternating magnetic field can be deduced.

[0047] The filter filters out microwaves other than the signal to be measured and transmits monochromatic microwaves;

[0048] The signal amplifier amplifies the output signal to improve the signal-to-noise ratio; the signal reflected from the cavity is filtered and amplified before being read out. The filter removes the residual drive signal to avoid amplifier saturation.

[0049] The rectifier diode rectifies the output signal, and the voltage signal measured by the voltmeter reflects the size of the alternating magnetic field;

[0050] The permanent magnet provides a stable bias magnetic field to the YIG ball, causing the YIG ball to precess at a specific frequency;

[0051] The signal readout system is used to detect the strength of the sideband signal.

[0052] The magnetic field sensitive detection device of the present invention utilizes a resonant cavity-magnon coupling system, based on phase modulation of the resonant cavity-magnon resonance excited by an alternating magnetic field, and can measure weak magnetic fields by detecting the output sideband signal intensity.

[0053] Example 2

[0054] The difference between the device for sensitive detection of alternating magnetic fields based on sideband regulation of a resonant cavity-magnon coupling system described in Example 1 is that:

[0055] The superconducting resonant cavity is any one of a microstrip line resonator (Stripline Resonator), a split ring resonator (Split Ring Resonator), a dielectric resonator (Dielectric Resonator), and a microwave resonant cavity (Microwave Cavity).

[0056] The magnetic material is any one of yttrium iron garnet, iron oxide, permalloy, and cobalt zirconium alloy; the magnetic material generates ferromagnetic resonance under microwave driving.

[0057] The bias magnetic field is any one of a neodymium iron boron magnet, a ferrite magnet, and an electromagnetic coil.

[0058] The signal readout system is any one of a vector network analyzer, a signal analyzer, HackRFOne, an oscilloscope, and a nanovoltmeter.

[0059] The signal amplifier is a low-noise high electron mobility transistor (HEMTs) with a gain of G 1 and gain G 2 All are 0-25dB;

[0060] Gain G 1 and gain G 2 Both are 25dB.

[0061] Figure 2 Schematic diagram of the transmission of the cavity magneton coupling system and the filter changing with frequency; the driving signal passes through the coupling system, and due to the modulation of the alternating magnetic field parallel to the external magnetic field, 2 The sideband signal is obtained at the point. Then it passes through the cylindrical resonant cavity as a filter, and its transmission is as follows Figure 2 As shown in the blue part of (a), Figure 2 In (b), the horizontal axis is the frequency of the alternating magnetic field, and the vertical axis is the voltage signal. Figure 2 (a) shows the variation of the transmission voltage of the resonant cavity magnetic oscillator coupling system with frequency, and the variation of the transmission voltage of the filter with frequency. Figure 2 (b) shows the size of the fixed alternating magnetic field, and the detection voltage changes with the frequency of the alternating magnetic field.

[0062] In ω 2 There is a cavity mode at ω 1 There is no mode, the signal to be measured can be 2The microwaves outside the range are filtered out. Then the output signal is amplified by two low noise amplifiers with an amplification factor of 25dB to improve the signal-to-noise ratio. Finally, it is rectified by a diode and measured by a voltmeter. Figure 2 The voltage signal shown in (b) reflects the magnitude of the alternating magnetic field.

[0063] The embodiment detects the 200 MHz alternating magnetic field component, such as Figure 3 As shown, alternating magnetic fields of 283nT, 502nT, 913nT and 1607T are detected respectively. Figure 3 (a) is a schematic diagram of an alternating magnetic field of 283nT. Figure 3 (b) is a schematic diagram of an alternating magnetic field of 502nT. Figure 3 (c) is a schematic diagram of an alternating magnetic field of 913nT. Figure 3 (d) is a schematic diagram of the alternating magnetic field of 1607T.

[0064] Figure 4 Schematic diagram of the change of alternating magnetic field with different voltage signals.

[0065] Example 3

[0066] A method for sensitively detecting an alternating magnetic field based on sideband regulation of a resonant cavity-magnon coupling system is implemented by the device for sensitively detecting an alternating magnetic field described in Embodiment 1 or 2, comprising:

[0067] A magnon, i.e. a YIG ball, is inserted into a superconducting resonant cavity to form a resonant cavity-magnon coupling system. A microwave source generates monochromatic microwaves to drive the resonant cavity-magnon coupling system. The microwaves radiated by the resonant cavity-magnon coupling system are filtered by a filter, and then amplified by two signal amplifiers. After being rectified by a rectifier diode, the voltage signal measured by a voltmeter reflects the size of the alternating magnetic field.

[0068] A yttrium iron garnet (YIG) sphere is placed in the center of the YBCO superconducting resonant cavity to form a resonant cavity-magnon coupling system; YIG has an extremely high electron spin density, which has reached 2×10 at room temperature. 28 spin / m 3 , with a linewidth as narrow as 1MHz. The bias magnetic field tunes the Larmor frequency of electrons in the YIG sphere to the cavity mode frequency and couples the magnon mode to the resonant cavity mode;

[0069] When magnons couple to the resonant cavity, the cavity mode splits into two hybrid modes; the resulting system can be described by quasiparticles of hole magnon polaritons (CMPs), whose dispersion relation is an anti-cross curve.

[0070] The permanent magnet provides an external magnetic field B. When an alternating magnetic field b provided by an alternating signal and parallel to the external magnetic field B is added 1 , and driven microwave in any of the two mixed modes (such as frequency ω i ) when a monochromatic microwave is applied to the b The alternating magnetic field b 1 Will produce a pair ω i Frequency modulation, i = 1, 2, at frequency ω i +nω b sidebands are generated at ω; however, since the resonant cavity-magnon system has only two modes, only 1 +nω b =ω 2 For weak magnetic fields, only the sideband corresponding to n = 1 has a significant amplitude, and for frequency ω b =2g 21 The detection of the alternating magnetic field is more sensitive. Then the filter filters out the microwaves outside the signal to be tested, amplifies and rectifies, and finally uses the positive correlation between the strength of the sideband signal and the size of the alternating magnetic field to measure the voltage signal through the voltmeter to reflect the size of the alternating magnetic field. 2 The power at the point is used to obtain the measured value of the alternating magnetic field. The relationship between the measured voltage U and the magnitude of the alternating magnetic field B is U = 0.058·B-13.3.

Claims

1. A sensitive detection device for alternating magnetic fields based on sideband regulation of a resonant cavity-magnon coupling system, characterized in that: include: Microwave source, superconducting resonant cavity, YIG sphere, filter, two signal amplifiers, rectifier diodes, permanent magnet and signal readout system; The resonant cavity-magnon coupling system includes a superconducting resonant cavity and a YIG ball, and the YIG ball is placed in the center of the superconducting resonant cavity; the microwave source generates monochromatic microwaves to drive the superconducting resonant cavity and the YIG ball, and after being modulated by the alternating magnetic field to be measured, the output signal passes through a filter, two signal amplifiers, a rectifier diode, and is finally measured by a voltmeter; The superconducting resonant cavity converts the magnitude of the alternating magnetic field into the intensity of the sideband signal through coupling with the magnetic material; Magnetic vibrators, or YIG balls, are used to sense alternating magnetic fields. When the alternating magnetic field acts on the YIG balls, the microwave-driven resonant cavity-magnetic vibrator coupling system generates sideband signals through coupling. By measuring the intensity of the sideband signals, the magnitude of the alternating magnetic field can be deduced. The filter filters out microwaves other than the signal to be measured and transmits monochromatic microwaves; The signal amplifier amplifies the output signal to improve the signal-to-noise ratio; The rectifier diode rectifies the output signal, and the voltage signal measured by the voltmeter reflects the size of the alternating magnetic field; The permanent magnet provides a bias magnetic field to the YIG ball, causing the YIG ball to precess at a certain frequency. The signal readout system is used to detect the strength of the sideband signal.

2. According to claim 1, the alternating magnetic field sensitive detection device based on the sideband regulation of the resonant cavity-magnon coupling system is characterized in that: The superconducting resonant cavity is any one of a microstrip line resonator, an open ring resonator, a dielectric resonator, and a microwave resonant cavity.

3. According to claim 1, the alternating magnetic field sensitive detection device based on the sideband regulation of the resonant cavity-magnon coupling system is characterized in that: The magnetic material is any one of yttrium iron garnet, iron oxide, Permalloy, and cobalt zirconium alloy; the magnetic material generates ferromagnetic resonance under microwave driving.

4. The device for sensitive detection of alternating magnetic fields based on sideband regulation of a resonant cavity-magnon coupling system according to claim 1, characterized in that: The bias magnetic field is any one of a neodymium iron boron magnet, a ferrite magnet, and an electromagnetic coil.

5. The device for sensitive detection of alternating magnetic fields based on sideband regulation of a resonant cavity-magnon coupling system according to claim 1, characterized in that: The signal readout system is any one of a vector network analyzer, a signal analyzer, HackRFOne, an oscilloscope, and a nanovoltmeter.

6. The device for sensitive detection of alternating magnetic fields based on sideband regulation of a resonant cavity-magnon coupling system according to claim 1, characterized in that: The signal amplifier is a low noise high electron mobility transistor, and the gain G1 and gain G2 are both 0-25dB.

7. The device for sensitive detection of alternating magnetic fields based on sideband regulation of a resonant cavity-magnon coupling system according to claim 1, characterized in that: The gain G1 and the gain G2 are both 25dB.

8. A method for sensitive detection of alternating magnetic fields based on sideband regulation of a resonant cavity-magnon coupling system, implemented by the alternating magnetic field sensitive detection device according to any one of claims 1 to 7, characterized in that: include: A magnon, i.e. a YIG ball, is inserted into a superconducting resonant cavity to form a resonant cavity-magnon coupling system. A microwave source generates monochromatic microwaves to drive the resonant cavity-magnon coupling system. The microwaves radiated by the resonant cavity-magnon coupling system are filtered by a filter, and then amplified by two signal amplifiers. After being rectified by a rectifier diode, the voltage signal measured by a voltmeter reflects the size of the alternating magnetic field.

9. The method for sensitive detection of alternating magnetic fields based on sideband regulation of a resonant cavity-magnon coupling system according to claim 8, characterized in that: A yttrium iron garnet (YIG) sphere is placed at the center of a yttrium barium copper oxide superconducting resonant cavity to form a resonant cavity-magnon coupling system; a bias magnetic field adjusts the Larmor frequency of electrons in the yttrium iron garnet (YIG) sphere to the cavity mode frequency and couples the magnon mode with the resonant cavity mode.

10. According to claim 8 or 9, a sensitive detection method of alternating magnetic field based on sideband regulation of a resonant cavity-magnon coupling system, when the magnon couples with the resonant cavity, the cavity mode splits into two mixed modes; The permanent magnet provides an external magnetic field B. When an alternating magnetic field b1 provided by an alternating signal and parallel to the external magnetic field B is added, and the driving microwave applies a monochromatic microwave to any of the two hybrid modes, the frequency is ω. b The alternating magnetic field b1 will produce an i Frequency modulation, i = 1, 2, at frequency ω i +nω b Sidebands are generated at b =ω2, the sidebands appear, and the other sidebands are suppressed; for weak magnetic fields, only the sideband component corresponding to n=1 has a significant amplitude, and for frequency ω b =2g 21 The detection of alternating magnetic fields is more sensitive. The filter then filters out microwaves other than the signal to be measured. After amplification and rectification, the intensity of the sideband signal is positively correlated with the size of the alternating magnetic field. The voltage signal measured by the voltmeter reflects the size of the alternating magnetic field.

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