A chip atomic vector magnetometer based on topological surface emitting laser

Abstract

The present invention discloses a chip atomic vector magnetometer based on a topological surface emitting laser, which is characterized by comprising a topological PCSEL, a beam shaping unit, a polarizer, a quarter wave plate, a voltage-controlled laser polarization rotator, an atomic gas chamber, a Wollaston prism, a dual-channel photodetector, a filter module, a laser frequency stabilization unit, a precession signal modulation and demodulation module, a laser polarization and Larmor magnetic field direction adjustment module, a two-dimensional Larmor magnetic field coil, a servo feedback module, a direct digital frequency synthesis module, and a high-stability crystal oscillator. The present invention uses a topological laser for a chip atomic vector magnetometer, innovatively realizes magnetic vector parameter measurement that is more immune to temperature fluctuations and has better performance to the external magnetic field, and can simultaneously measure the complete information of the vector magnetic field, which can be used in the fields of material defect detection, mineral oil and gas exploration, and underwater magnetic target positioning.

Description

Technical Field

[0001] The invention belongs to the field of quantum magnetic detection, and in particular relates to a chip atomic vector magnetometer based on a topological body surface emitting laser. Background Art

[0002] The precise measurement of magnetic vector field, as an important means to study the properties of magnets and analyze the form of matter, plays an important role in practical applications, such as the measurement of biological magnetic field, the study of topography, the detection of material defects, the exploration of mineral oil and gas, the positioning of underwater magnetic targets, etc. At present, the types of magnetometers that have been widely used and have relatively mature technology include fluxgate magnetometers, nuclear precession magnetometers, optically pumped scalar magnetometers and superconducting magnetometers, etc. However, these magnetometers are all scalar magnetometers and cannot obtain all the information of the magnetic field; measuring and obtaining all the information of the magnetic field has become an inevitable trend in the development of atomic magnetometers. The magnetometer provided by the present invention can not only measure the modulus of the magnetic field, but also measure the direction of the magnetic field to obtain complete information of the magnetic field.

[0003] Photonic Crystal Surface Emitting Laser (PCSEL) can control the evolution of topological charge to construct a topological protection mechanism, which can keep the lasing mode unchanged under the continuous change of structure and material parameters, thereby greatly improving the mode selectivity and stability of PCSEL and achieving robust single-mode lasing under process errors and environmental disturbances. In particular, the high-performance topological bulk surface emitting laser, which has a diameter of only a few microns, has good vertical emission directionality, narrow line width, and single-mode lasing characteristics. Topological bulk PCSEL has the characteristics of high power, surface emission and stable single-mode operation, and can achieve full spectrum, large area, extremely low divergence angle, and high-power laser output. It is a new type of laser with great potential. It can be used to overcome the shortcomings of traditional semiconductor lasers such as large divergence angle, poor monochromaticity, and low brightness. It has important application prospects in the fields of atomic clocks, quantum precision measurement, lidar, space communications, sensing and laser processing.

[0004] Traditional chip-type optically pumped atomic magnetometers usually use vertical cavity surface emitting lasers (VCSEL) and distributed feedback lasers (DFB), and conventional atomic magnetometers rely on the magnetic resonance principle of the outermost electron magnetic moment to obtain the magnetic field modulus, and cannot obtain the direction information of the magnetic field to be measured. In order to solve the above problems, the present invention proposes a chip atomic vector magnetometer based on topological surface emitting lasers, which overcomes the problem that existing magnetometers are difficult to measure the direction of the magnetic field, and uses the topological surface emitting laser as the laser source, so that the volume occupied by the laser is greatly reduced, and the chipization of the overall system is realized. Summary of the invention

[0005] In view of the problems existing in the prior art, the object of the present invention is to provide a chip atomic vector magnetometer based on topological surface emitting laser.

[0006] The present invention uses a topological surface-emitting laser to replace the traditional light source. Its diameter is only a few microns, and it has good vertical emission directionality, narrow line width, and single-mode lasing characteristics. It also has the characteristics of high power, surface emission, and stable single-mode operation, and can achieve full spectrum, large area, extremely low divergence angle, and high-power laser output.

[0007] At the same time, in order to overcome the problem that the existing magnetometer cannot measure the direction of the magnetic field, the present invention obtains the influence of the precession of the magnetic moment in the magnetic field to be measured on the laser energy and polarization direction, and provides a method for measuring the vector magnetic field using an atomic gas chamber. The magnetometer can not only measure the magnetic field modulus, but also measure the direction of the magnetic field, thereby obtaining complete magnetic field information.

[0008] The technical solution of this program is as follows:

[0009] The chip atomic vector magnetometer based on topological surface emitting laser includes: a topological PCSEL 1, a beam shaping unit (including a focusing lens 2 and a collimating lens 3), a polarizer 4, a quarter-wave plate 5, a voltage-controlled laser polarization rotator 6, an atomic gas chamber 7, a Wollaston prism 8, a dual-channel photodetector 9, a photocurrent amplifier 10, a filter module 11, a laser frequency stabilization unit (including a DC signal modulation and demodulation module 12, a DC signal servo feedback module 13, and a voltage-controlled voltage source 14), a precession signal demodulation module 15, a laser polarization and Larmor magnetic field direction adjustment module 16, a two-dimensional Larmor magnetic field coil 17, a servo feedback module 18, a direct digital frequency synthesis module 19, a high-stability crystal oscillator 20, a topological PCSEL thermal insulation control device 21, and an atomic gas chamber thermal insulation control device 22.

[0010] The topological state PCSEL1 (reference patent document with publication number CN113805462A) is used as a light source to emit laser light that can be used to excite the transition of the sensing medium in the atomic gas chamber 7;

[0011] The focusing lens 2 and the collimating lens 3 are used to collimate and shape the light emitted by the topological state PCSEL1 into parallel light;

[0012] The polarizer 4 is used to change the polarization state of the laser into linear polarized light incident on the quarter wave plate 5;

[0013] The quarter wave plate 5 is used to convert incident linearly polarized light into circularly polarized light;

[0014] The voltage-controlled laser polarization rotator 6 is used to generate and control the polarization direction of circularly polarized light;

[0015] The atomic gas chamber 7 is filled with high-purity sensing atoms (such as cesium, rubidium, potassium, sodium, helium, etc.) for generating magnetic resonance after being excited by the incident light beam and sensing the magnetic field to be measured. At the same time, the gas chamber needs to be treated with anti-relaxation (such as filling with appropriate buffer gas, or coating the inner surface of the gas chamber with high molecular materials such as paraffin wax);

[0016] The Wollaston prism 8 decomposes the circularly polarized light into two components with mutually perpendicular polarization directions;

[0017] The dual-channel photoelectric detector 9 converts the optical signals of two mutually perpendicular polarization direction components into electrical signals respectively;

[0018] The photocurrent amplifier 10 appropriately amplifies the photocurrent output by the photodetector 9;

[0019] The filter module 11 will separate the DC signal and the high-frequency signal from the amplified electrical signal;

[0020] The DC signal modulation and demodulation module 12 modulates and demodulates the DC signal output from the filter module 11;

[0021] The DC signal servo feedback module 13 appropriately amplifies and filters the demodulated signal and then feeds it back to the voltage-controlled voltage source 14;

[0022] The voltage-controlled voltage source 14 provides working current for the topological state PCSEL1 and controls the laser frequency;

[0023] The precession signal demodulation module 15 demodulates the high frequency signal output from the filter module 11;

[0024] The laser polarization and Larmor magnetic field direction adjustment module 16 synchronously adjusts the laser polarization direction and the Larmor magnetic field direction, and keeps the two parallel, and outputs an electrical signal containing Larmor magnetic field direction information;

[0025] The two-dimensional Larmor magnetic field coil 17 is used to generate a Larmor magnetic field that excites magnetic moment precession and has an adjustable polarization direction;

[0026] The servo feedback module 18 appropriately amplifies and filters the optical power current second harmonic signal output by the precession signal demodulation module 15 to control the direct digital frequency synthesis module 19;

[0027] The direct digital frequency synthesis module 19 outputs an alternating current signal to the two-dimensional Larmor magnetic field coil 17 to control the Larmor precession frequency of the atoms in the magnetic field to be measured; and outputs an electrical signal containing the Larmor precession frequency;

[0028] The highly stable crystal oscillator 20 provides a standard frequency reference for the direct digital frequency synthesis module 19;

[0029] The topological PCSEL insulation and temperature control device 21 and the atomic gas chamber insulation and temperature control device 22 insulate and control the working environment of the topological PCSEL and the atomic gas chamber 7, making their operation more stable and reducing the impact of external temperature fluctuations on the chip magnetometer.

[0030] The specific adjustment method of the chip atomic vector magnetometer based on the topological surface emitting laser of the present invention is:

[0031] The topological state PCSEL1 outputs a laser whose frequency is locked to the transition spectrum of the sensing atom under the control of the voltage-controlled voltage source 14, and is converted into a parallel laser beam with controllable polarization direction through the focusing lens 2, the collimating lens 3, the polarizer 4, the quarter-wave plate 5, and the voltage-controlled laser polarization rotator 6, and is incident on the magnetic atomic gas chamber 7. The transmitted light beam of the gas chamber is incident on the dual-channel photodetector 9 through the Wollaston prism 8 for photoelectric conversion, and the output photocurrent is appropriately amplified by the photocurrent amplifier 10; the DC signal and the high-frequency signal in the photocurrent are separated by the filter module 11, wherein the DC component is used to control the laser frequency, and the high-frequency component is used for magnetic field measurement.

[0032] The DC signal modulation and demodulation module 12 modulates and demodulates the DC signal, and controls the DC signal servo feedback module 13, and finally feeds back to the voltage-controlled voltage source 14 to achieve the laser frequency stabilization of PCSEL1.

[0033] The precession signal demodulation module 15 demodulates the high-frequency signal, which contains the second harmonic information of the precession of the light polarization direction, and can be used to obtain a direction angle of the magnetic field to be measured. At the same time, the first harmonic of the optical power current is used to control the laser polarization and the Larmor magnetic field direction adjustment module 16 to obtain another direction angle information of the magnetic field to be measured. The second harmonic of the optical power current is controlled by the servo feedback module 18 and the direct digital frequency synthesis module 19 to control the frequency of the Larmor signal in the two-dimensional Larmor magnetic field coil 17 to obtain the modulus of the magnetic field to be measured.

[0034] The high stability crystal oscillator 20 provides a standard frequency reference for the direct digital frequency synthesis module. The temperature insulation and control device 21 and the atomic gas chamber temperature insulation and control device 22 insulate and control the working environment of the topological body PCSEL1 and the atomic gas chamber 7 to make their work more stable and reduce the impact of external temperature fluctuations on the chip magnetometer.

[0035] The present invention has the following beneficial effects:

[0036] The present invention provides a chip atomic vector magnetometer based on topological body surface emitting laser, which uses topological body surface emitting laser to replace traditional light source, and has excellent characteristics such as small size, vertical emission, narrow line width, high power, surface emission, single-mode lasing, etc., and can achieve full spectrum, large area, extremely low divergence angle, high power laser output, and has important application prospects in the field of chip atomic vector magnetometer. At the same time, the invented atomic vector magnetometer can simultaneously measure the complete information of the vector magnetic field, and can be used in the fields of material defect detection, mineral oil and gas exploration, underwater magnetic target positioning, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A chip-based atomic vector magnetometer based on topological surface-emitting lasers.

[0038] Figure numerals: 1-topological PCSEL, 2-focusing lens, 3-collimating lens, 4-polarizer, 5-quarter wave plate, 6-voltage-controlled laser polarization rotator, 7-atomic gas chamber, 8-Wollaston prism, 9-dual-channel photodetector, 10-photocurrent amplifier, 11-filter module, 12-DC signal modulation and demodulation module, 13-DC signal servo feedback module, 14-voltage-controlled voltage source, 15-precession signal demodulation module, 16-laser polarization and Larmor magnetic field direction adjustment module, 17-two-dimensional Larmor magnetic field coil, 18-servo feedback module, 19-direct digital frequency synthesis module, 20-high-stability crystal oscillator, 21-topological PCSEL thermal insulation control device, 22-atomic gas chamber thermal insulation control device. DETAILED DESCRIPTION

[0039] The present invention is further described in detail below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention but not to limit the scope of the present invention.

[0040] like Figure 1 As shown, the schematic diagram of the chip atomic vector magnetometer based on the topological surface emitting laser of the present invention includes: a topological PCSEL 1, a focusing lens 2, a collimating lens 3, a polarizer 4, a quarter wave plate 5, a voltage-controlled laser polarization rotator 6, an atomic gas chamber 7, a Wollaston prism 8, a dual-channel photodetector 9, a photocurrent amplifier 10, a filter module 11, a DC signal modulation and demodulation module 12, a DC signal servo feedback module 13, a voltage-controlled voltage source 14, a precession signal demodulation module 15, a laser polarization and Larmor magnetic field direction adjustment module 16, a two-dimensional Larmor magnetic field coil 17, a servo feedback module 18, a direct digital frequency synthesis module 19, a high-stability crystal oscillator 20, a topological PCSEL thermal insulation control device 21, and an atomic gas chamber thermal insulation control device 22.

[0041] The assembly relationship between the various components is as follows: the atomic gas chamber 7 is placed in the magnetic field to be measured, and the topological body PCSEL1 emits a laser that resonates with the atomic transition, which passes through the focusing lens 2, the collimating lens 3, the polarizer 4, the quarter-wave plate 5, the voltage-controlled laser polarization rotator 6, the atomic gas chamber 7, the Wollaston prism 8, the dual-channel photodetector 9, the photocurrent amplifier 10, and the filter module 11 to separate the DC component and the AC component in the photocurrent, wherein the DC component passes through the DC signal modulation and demodulation module 12, the DC signal servo feedback module 13, and the voltage-controlled voltage source 14 in turn, and is input into the topological body PCSEL1; wherein the AC component outputs a magnetic field direction angle through the precession signal demodulation module 15, and obtains a direction angle information of the magnetic field through the laser polarization and Larmor magnetic field direction adjustment module 16, and controls the frequency of the Larmor signal in the two-dimensional Larmor magnetic field coil 1 through the servo feedback module 18 and the direct digital frequency synthesis module 19 to obtain the modulus of the magnetic field to be measured.

[0042] The high stability crystal oscillator 20 provides a frequency reference for the direct digital frequency synthesis module 19. The temperature insulation and control device 21 and the atomic gas chamber temperature insulation and control device 22 insulate and control the working environment of the PCSEL and the atomic gas chamber 7 to make their operation more stable and reduce the influence of external temperature fluctuations on the chip magnetometer.

[0043] The working process and principle are as follows:

[0044] The topological state PCSEL1 emits a modulated light beam for exciting atomic transitions in the gas chamber 7, which is collimated and shaped into parallel light by lens 2 and collimating lens 3, becomes circularly polarized light by polarizer 4 and quarter wave plate 5, and changes the polarization direction of the laser by voltage-controlled laser polarization rotator 6, and is incident on the magnetic atomic gas chamber 7. The transmitted light beam of the atomic gas chamber is incident on the dual-channel photodetector 9 through Wollaston prism 8, and the output photocurrent is appropriately amplified by photocurrent amplifier 10; the DC component and high-frequency component in the photocurrent are separated by filter module 11. The DC signal modulation and demodulation module 12 modulates and demodulates the DC component, and controls the DC signal servo feedback module 13, which is fed back to the voltage-controlled voltage source 14 to lock the frequency of PCSEL1 to the atomic transition spectrum. The precession signal demodulation module 15 demodulates the AC component, which contains the second harmonic information of the precession of the light polarization direction, so as to obtain a direction angle of the magnetic field to be measured. At the same time, the first harmonic of the optical power current is used to control the laser polarization and the Larmor magnetic field direction adjustment module 16 to obtain another direction angle information of the magnetic field to be measured. The second harmonic of the optical power current is controlled by the servo feedback module 18 and the direct digital frequency synthesis module 19 to control the frequency of the Larmor signal in the two-dimensional Larmor magnetic field coil 17 to obtain the modulus of the magnetic field to be measured.

[0045] Although the specific embodiments of the present invention are disclosed for the purpose of illustration, the purpose is to help understand the content of the present invention and implement it accordingly, those skilled in the art will understand that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the present invention should not be limited to the content disclosed in the best embodiment, and the scope of the present invention is subject to the scope defined in the claims.

Claims

1. A chip atomic vector magnetometer based on topological surface emitting laser, characterized in that: It includes a topological PCSEL (1), a beam shaping unit, a polarizer (4), a quarter wave plate (5), a voltage-controlled laser polarization rotator (6), an atomic gas chamber (7), a Wollaston prism (8), a dual-channel photodetector (9), a filter module (11), a laser frequency stabilization unit, a precession signal demodulation module (15), a laser polarization and Larmor magnetic field direction adjustment module (16), a two-dimensional Larmor magnetic field coil (17), a servo feedback module (18), a direct digital frequency synthesis module (19), and a high-stability crystal oscillator (20); The topological PCSEL (1) is used to emit laser light that excites the transition of the sensing medium in the atomic gas chamber (7); The laser light output by the topological PCSEL (1) is shaped into parallel light by the beam shaping unit and is incident on the polarizer (4); The polarizer (4) is used to change the polarization state of the incident laser light into linear polarized light incident on the quarter wave plate (5); The quarter wave plate (5) is used to convert incident linear polarized light into circular polarized light and then incident on the voltage-controlled laser polarization rotator (6); The voltage-controlled laser polarization rotator (6) is used to control the polarization direction of the circularly polarized light and to inject the regulated circularly polarized laser light into the atomic gas chamber (7); The atomic gas chamber (7) is filled with a sensing medium for generating magnetic resonance after being excited by an incident light beam and sensing a magnetic field to be measured; The Wollaston prism (8) is used to decompose the laser light output by the atomic gas chamber (7) into two optical signals with polarization directions perpendicular to each other; The dual-channel photoelectric detector (9) is used to convert two optical signals with mutually perpendicular polarization directions into electrical signals respectively; The filter module (11) separates a direct current signal and a high-frequency signal from the electrical signal; The laser frequency stabilization unit is used to generate a laser frequency stabilization control signal according to the DC signal output by the filter module (11) and send it to the topological PCSEL (1); The precession signal demodulation module (15) is used to demodulate the high-frequency signal output by the filter module (11); The laser polarization and Larmor magnetic field direction adjustment module (16) is used to obtain the Larmor magnetic field direction based on the demodulation signal output by the precession signal demodulation module (15) to control the voltage-controlled laser polarization rotator (6) to adjust the polarization direction of the circularly polarized light, so that the polarization direction of the circularly polarized light remains parallel to the Larmor magnetic field direction; The high-stability crystal oscillator (20) is used to provide a frequency reference for the direct digital frequency synthesis module (19); The servo feedback module (18) is used to amplify and filter the current second harmonic signal output by the precession signal demodulation module (15) and then send it to the direct digital frequency synthesis module (19); The direct digital frequency synthesis module (19) is used to synthesize the received current second harmonic signal with the frequency reference to obtain an alternating current signal and send it to the two-dimensional Larmor magnetic field coil (17); The two-dimensional Larmor magnetic field coil (17) is used to output a Larmor magnetic field with adjustable polarization direction to control the Larmor precession frequency of the sensing medium in the atomic gas chamber (7) in the magnetic field to be measured, based on the electrical signal containing Larmor magnetic field direction information output by the laser polarization and Larmor magnetic field direction adjustment module (16) and the electrical signal containing Larmor precession frequency output by the direct digital frequency synthesis module (19).

2. The chip atomic vector magnetometer according to claim 1, characterized in that: The beam shaping unit comprises a focusing lens (2) and a collimating lens (3) which are arranged in sequence along the incident direction of the beam.

3. The chip atomic vector magnetometer according to claim 1 or 2, characterized in that: The laser frequency stabilization unit comprises a DC signal modulation and demodulation module (12), a DC signal servo feedback module (13), and a voltage-controlled voltage source (14); the DC signal modulation and demodulation module (12) modulates and demodulates the DC signal output by the filter module (11); the DC signal servo feedback module (13) is used to amplify and filter the signal output by the DC signal modulation and demodulation module (12), and then feed it back to the voltage-controlled voltage source (14); the voltage-controlled voltage source (14) is used to provide working current for the topological PCSEL (1) and generate a laser frequency stabilization control signal to control the laser frequency.

4. The chip atomic vector magnetometer according to claim 1 or 2, characterized in that: The sensing medium is cesium, rubidium, potassium, sodium or helium.

5. The chip atomic vector magnetometer according to claim 1 or 2, characterized in that: The electrical signal output by the dual-channel photoelectric detector (9) is amplified by a photocurrent amplifier (10) and then input into the filter module (11).

6. The chip atomic vector magnetometer according to claim 1 or 2, characterized in that: It also comprises a topological PCSEL heat preservation control device (21) for heat preservation and temperature control of the working environment of the topological PCSEL (1).

7. The chip atomic vector magnetometer according to claim 1 or 2, characterized in that: It also comprises an atomic gas chamber heat preservation control device (22) for heat preservation and temperature control of the working environment of the atomic gas chamber (7).

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