A three-axis serf atomic magnetometer based on multi-pass reflection of pump light

Abstract

A three-axis SERF atomic magnetometer based on multi-pass reflection of pump light, which uses a mirror to change the propagation direction of pump light multiple times, realizes four times of pump light passing through an alkali metal cell, the pump light contains three-axis magnetic field information, and realizes high-sensitivity measurement of three-axis magnetic field by modulation and demodulation technology, the scheme is simple in structure, easy to miniaturize and integrate, and overcomes the difficulty of high-sensitivity simultaneous measurement of three-axis magnetic field in the classical single-beam and pump-detection double-beam SERF atomic magnetometer, and the three-axis SERF atomic magnetometer is characterized in that it comprises an alkali metal cell with a square cross section, the square cross section is perpendicular to the y-axis, the first diagonal vertex connecting line is parallel to the z-axis, the second diagonal vertex connecting line is parallel to the x-axis, the left upper edge is a pump light incident side, the right upper edge is attached with a first mirror, the right lower edge is attached with a second mirror, and the left lower edge is attached with a third mirror, and the pump light forms first to fourth pass pump light in sequence after being incident on the left upper edge along the z-axis.

Description

Technical Field

[0001] This invention belongs to the technical field of spin-exchange relaxation-free (SERF) atomic magnetometers, specifically relating to a triaxial SERF atomic magnetometer based on multi-path reflection of pump light. Background Technology

[0002] Atomic magnetometers based on the SERF effect have achieved ultra-high sensitivity in magnetic field measurement, reaching 0.16 fT / Hz. 1 / 2 The sensitivity of magnetic field measurements is constantly being improved, pushing the limits towards the aT level. Benefiting from the high sensitivity, ease of miniaturization and integration, and room-temperature operation of the SERF atomic magnetometer, it has broad application prospects in cutting-edge science, geomagnetic science, and life sciences.

[0003] Polarized alkali metal atoms are generally highly sensitive to magnetic fields perpendicular to the pump light. Therefore, classic single-beam and pump-detection dual-beam SERF atomic magnetometers typically only have high sensitivity for measuring magnetic fields in one or two axes, making it difficult to measure the magnetic field along the pump axis with high sensitivity. However, simultaneously measuring the triaxial magnetic field of the magnetic source is beneficial for more accurate analysis of the source and obtaining more valuable information about it. Current methods for measuring triaxial magnetic fields include those using multiple gas cells, multiple pump lights, and multiple detection lights, but these all suffer from drawbacks such as complex optical paths and increased components, which hinder miniaturization and limit the application of triaxial SERF atomic magnetometers.

[0004] Based on the above problems, this invention proposes a triaxial SERF atomic magnetometer based on pump light multipath reflection. Summary of the Invention

[0005] The technical problem to be solved by this invention is to overcome the shortcomings of the prior art and propose a triaxial SERF atomic magnetometer based on pump light multi-path reflection. By using a mirror to change the propagation direction of the pump light multiple times, the pump light passes through the alkali metal gas cell four times. The pump light contains triaxial magnetic field information. Through modulation and demodulation technology, a single pump light can be used to simultaneously measure the triaxial magnetic field with high sensitivity. This scheme has a simple structure, is easy to miniaturize and integrate, and also overcomes the difficulty of achieving high-sensitivity simultaneous measurement of triaxial magnetic fields in classic single-beam and pump-detection dual-beam SERF atomic magnetometers.

[0006] The technical solution of the present invention is as follows:

[0007] A triaxial SERF atomic magnetometer based on pump light multipath reflection is characterized by comprising an alkali metal gas cell with a square cross-section. The square cross-section is perpendicular to the y-axis, the line connecting the first opposite vertices of the square cross-section is parallel to the z-axis, the line connecting the second opposite vertices of the square cross-section is parallel to the x-axis, the upper left side of the square cross-section is the pump light incident side, a first reflecting mirror is attached to the upper right side of the square cross-section, a second reflecting mirror is attached to the lower right side of the square cross-section, and a third reflecting mirror is attached to the lower left side of the square cross-section. The pump light is incident along the z-axis on the upper left side and then... The alkali metal gas chamber generates a first-stage pump light that reaches the upper right first reflector. The first reflector reflects the first-stage pump light along the x-axis into a second-stage pump light that reaches the lower right second reflector. The second reflector reflects the second-stage pump light along the z-axis into a third-stage pump light that reaches the lower left third reflector. The third reflector reflects the third-stage pump light along the x-axis into a fourth-stage pump light that reaches the upper left pump light incident side. The fourth-stage pump light exits from the upper left along the x-axis and is connected to the data acquisition unit via a photodetector, a transimpedance amplifier, and a lock-in amplifier.

[0008] The alkali metal gas chamber is located inside the oven, the oven is located inside the triaxial magnetic coil, the triaxial magnetic coil is located inside the magnetic shielding barrel, and the triaxial magnetic coil is connected to the signal generator.

[0009] The pump light comes from a laser, which is connected to the upper left pump light incident side in sequence through a polarization-maintaining fiber, a collimator, a polarizer, and a quarter-wave plate.

[0010] The laser is a distributed Bragg reflector, a distributed feedback laser, or a vertical cavity surface-emitting laser.

[0011] The oven is made of aluminum nitride or boron nitride. A heating film is attached to the surface of the oven. The heating film is made of double-plane copper wires arranged in an orderly manner. A platinum resistance thermometer is attached to the oven.

[0012] Including the following expressions:

[0013]

[0014] Where P all It is the total spin polarization. It is the spin polarization in the first stroke of the pump light along the z-axis. It is the spin polarization in the second path of the pump light along the x-axis. It is the spin polarization in the third stroke pump light along the z-axis. It is the spin polarization in the fourth path of the pump light along the x-axis.

[0015] Including the following expressions:

[0016]

[0017] in J0 is the optical pumping rate of the first path pump light along the z-axis, J1 is the zeroth-order Bessel function, and γ is the first-order Bessel function. e It is the electron gyromagnetic ratio, B x0 It is the remanence along the x-axis. It is the x-axis modulation frequency, and t is time. B is the relaxation rate in the pump light during the first stroke along the z-axis. y0 It is y-axis remanence. It is the y-axis modulation frequency;

[0018] It is the optical pumping rate of the pump light along the second path of the x-axis. B is the relaxation rate in the second stroke of the pump light along the x-axis. z0 It is z-axis remanence. It is the z-axis modulation frequency;

[0019] It is the optical pumping rate of the pump light along the third path of the z-axis. It is the relaxation rate in the pump light along the third stroke of the z-axis;

[0020] It is the optical pumping rate of the pump light along the fourth path of the x-axis. It is the relaxation rate in the pump light along the fourth path along the x-axis.

[0021] The technical effects of this invention are as follows: This invention provides a triaxial SERF atomic magnetometer based on multi-path reflection of pump light. It uses a reflector to repeatedly change the propagation direction of the pump light, enabling the pump light to pass through the alkali metal gas cell four times. This pump light contains triaxial magnetic field information. Through modulation and demodulation technology, a single pump light can simultaneously and with high sensitivity measure the triaxial magnetic field. This scheme has a simple structure, is easy to miniaturize and integrate, and overcomes the difficulty of achieving simultaneous and high-sensitivity measurement of triaxial magnetic fields in classic single-beam and pump-detection dual-beam SERF atomic magnetometers. The invention is characterized by an alkali metal gas cell with a square cross-section, the square cross-section being perpendicular to the y-axis, the line connecting the first diagonal vertices parallel to the z-axis, the line connecting the second diagonal vertices parallel to the x-axis, the upper left side being the pump light incident side, the upper right side having a first reflector attached, the lower right side having a second reflector attached, and the lower left side having a third reflector attached. The pump light, after incident along the z-axis on the upper left side, sequentially forms the first to fourth paths of pump light.

[0022] The advantages of this invention compared to the prior art are:

[0023] 1. The triaxial SERF atomic magnetometer based on pump light multi-path reflection described in this invention can achieve high-sensitivity simultaneous measurement of triaxial magnetic fields by using a single pump light beam and an alkali metal gas cell. Compared with schemes using multiple gas cells, multiple pump lights, and multiple detection lights, the proposed scheme has a simple optical path and hardware structure, which is beneficial for the miniaturization of the triaxial SERF atomic magnetometer.

[0024] 2. The triaxial SERF atomic magnetometer based on multi-path reflection of pump light described in this invention first involves a single pump light being guided into the magnetometer's optical path by a polarization-maintaining fiber. Then, the pump light is incident at a 45° angle along the first light-passing surface of the alkali metal cell. Next, the pump light is reflected by three plane mirrors, achieving four sequential passes through the same alkali metal cell, with each pair of pump light passing perpendicular to the others. Based on this rational design, a single pump light beam can achieve highly sensitive simultaneous measurement of triaxial magnetic fields, overcoming the limitations of classic single-beam atomic magnetometers and pump-detection dual-beam atomic magnetometers in achieving highly sensitive measurement of the magnetic field along the pump axis.

[0025] 3. The triaxial SERF atomic magnetometer based on pump light multi-path reflection described in this invention enables a single pump light to pass through the same alkali metal gas cell four times, increasing the interaction distance between the light and atoms (increasing the optical path), which can improve the intensity and sensitivity of the triaxial magnetic field response signal. Attached Figure Description

[0026] Figure 1 A schematic diagram of a three-axis SERF atomic magnetometer based on pump light multi-path reflection is provided for implementing this invention.

[0027] Figure 2 yes Figure 1 A schematic diagram of the polarization state of alkali metal atoms in a medium alkali metal gas chamber during operation. Figure 2 The solid circles with arrows represent alkali metal atoms, while the hollow circles represent buffer and quenching gases, such as nitrogen (N2).

[0028] Figure 3 yes Figure 1 Schematic diagram of the structure of the medium alkali metal gas chamber.

[0029] The reference numerals in the attached figures are explained as follows: 1 - Laser (e.g., DBR, Distributed Bragg Reflector; DFB, Distributed Feedback Laser; VCSEL, Vertical Cavity Surface Emitting) Laser (Vertical-Cavity Surface-Emitting Laser); 2-Polarization-Maintaining Fiber; 3-Collider; 4-Polarizer; 5-1 / 4 Waveplate; 6-Pump Beam; 7-Alkali Metal Cell; 8-First Reflector; 9-Second Reflector; 10-Third Reflector; 11-Photodetector; 12-Transimpedance Amplifier; 13-Lock-in Amplifier; 14-Data Acquisition Unit; 15-Signal Generator; 16-Triaxial Magnetic Coil; 17-Magnetic Shielding Barrel; 61-First Pump Beam; 62-Second Pump Beam; 63-Third Pump Beam; 64-Fourth Pump Beam; 71-First Light-Passing Surface of Alkali Metal Cell; 72-Second Light-Passing Surface of Alkali Metal Cell; 73-Third Light-Passing Surface of Alkali Metal Cell; 74-Fourth Light-Passing Surface of Alkali Metal Cell; 75-Gas Handle. Detailed Implementation

[0030] The following is in conjunction with the attached diagram ( Figures 1-3 The invention will be described in the following sections and examples.

[0031] Figure 1 A schematic diagram of a three-axis SERF atomic magnetometer based on pump light multi-path reflection is provided for implementing this invention. Figure 2 yes Figure 1 A schematic diagram of the polarization state of alkali metal atoms in a medium alkali metal gas chamber during operation. Figure 2 The solid circles with arrows represent alkali metal atoms, while the hollow circles represent buffer and quenching gases, such as nitrogen (N2). Figure 3 yes Figure 1 Schematic diagram of the medium-alkali metal gas chamber structure. (Reference) Figures 1 to 3As shown, a triaxial SERF atomic magnetometer based on pump light multi-path reflection includes an alkali metal gas cell 7 with a square cross-section. The square cross-section is perpendicular to the y-axis, the line connecting the first opposite vertices of the square cross-section is parallel to the z-axis, and the line connecting the second opposite vertices of the square cross-section is parallel to the x-axis. The upper left side of the square cross-section is the pump light incident side. A first reflector 8 is attached to the upper right side of the square cross-section, a second reflector 9 is attached to the lower right side of the square cross-section, and a third reflector 10 is attached to the lower left side of the square cross-section. The pump light 6 is incident along the z-axis on the upper left side and then forms a reflection within the alkali metal gas cell 7, reaching the upper right side. The first pump light 61 of the first reflector 8 is reflected along the x-axis to form the second pump light 62 of the second reflector 9 at the lower right. The second reflector 9 reflects the second pump light 62 along the z-axis to form the third pump light 63 of the third reflector 10 at the lower left. The third reflector 10 reflects the third pump light 63 along the x-axis to form the fourth pump light 64 of the pump light incident side at the upper left. The fourth pump light 64 exits from the upper left side along the x-axis and is connected to the data acquisition unit 14 in sequence through the photodetector 11, the transimpedance amplifier 12, and the lock-in amplifier 13.

[0032] The alkali metal gas chamber 7 is located inside an oven, which is located inside a triaxial magnetic coil 16. The triaxial magnetic coil 16 is located inside a magnetic shielding barrel 17, and is connected to a signal generator 15. The pump light 6 originates from a laser 1, which is connected to the upper left pump light incident side via a polarization-maintaining fiber 2, a collimator 3, a polarizer 4, and a quarter-wave plate 5. The laser 1 is a distributed Bragg reflector, a distributed feedback laser, or a vertical-cavity surface-emitting laser. The oven is made of aluminum nitride or boron nitride material, and a heating film is attached to the surface of the oven. The heating film is composed of orderly arranged biplane copper wires, and a platinum resistance thermometer is attached to the oven.

[0033] Including the following expressions:

[0034]

[0035] Where P all It is the total spin polarization. It is the spin polarization in the first stroke of the pump light along the z-axis. It is the spin polarization in the second path of the pump light along the x-axis. It is the spin polarization in the third stroke pump light along the z-axis. It is the spin polarization in the fourth path of the pump light along the x-axis.

[0036] Including the following expressions:

[0037]

[0038] in J0 is the optical pumping rate of the first path pump light along the z-axis, J1 is the zeroth-order Bessel function, and γ is the first-order Bessel function. e It is the electron gyromagnetic ratio, B x0 It is the remanence along the x-axis. It is the x-axis modulation frequency, and t is time. B is the relaxation rate in the pump light during the first stroke along the z-axis. y0 It is y-axis remanence. It is the y-axis modulation frequency;

[0039] It is the optical pumping rate of the pump light along the second path of the x-axis. B is the relaxation rate in the second stroke of the pump light along the x-axis. z0 It is z-axis remanence. It is the z-axis modulation frequency;

[0040] It is the optical pumping rate of the pump light along the third path of the z-axis. It is the relaxation rate in the pump light along the third stroke of the z-axis;

[0041] It is the optical pumping rate of the pump light along the fourth path of the x-axis. It is the relaxation rate in the pump light along the fourth path along the x-axis.

[0042] This invention relates to a triaxial SERF atomic magnetometer based on multi-path reflection. First, a single pump light is guided into the magnetometer's optical path by a polarization-maintaining fiber. Then, the pump light is incident at a 45° angle along the first light-transmitting surface of the alkali metal cell. Next, the pump light is reflected sequentially by three plane mirrors, achieving four passes through the same alkali metal cell, with each pair of pump lights passing perpendicular to the others. Based on this rational design, a single pump light beam can achieve highly sensitive simultaneous measurement of triaxial magnetic fields, overcoming the limitations of classic single-beam atomic magnetometers and pump-detection dual-beam atomic magnetometers in achieving high sensitivity in measuring the magnetic field along the pump axis. Furthermore, this scheme is simple in structure, easy to miniaturize and integrate, and beneficial for the application of array-type triaxial SERF atomic magnetometers. In addition, the single pump light passing through the same alkali metal cell four times increases the interaction distance between the light and atoms, improving the intensity and sensitivity of the triaxial magnetic field response signal.

[0043] Example 1

[0044] In this embodiment, a triaxial SERF atomic magnetometer structure based on pump light multipath reflection is shown below. Figure 1 As shown. Figure 2 This indicates the polarization state of alkali metal atoms in the alkali metal chamber of the aforementioned triaxial SERF atomic magnetometer based on pump light multipath reflection during operation.

[0045] A triaxial SERF atomic magnetometer based on pump light multipath reflection includes an alkali metal gas cell assembly, an optical path assembly, a signal detection assembly, an active magnetic compensation assembly, and a passive magnetic compensation assembly. The alkali metal gas cell assembly includes an alkali metal gas cell 7, an oven, a heating film, and a platinum resistance thermometer. The alkali metal gas cell 7 is composed of a gas cell body made of aluminosilicate glass and a gas handle 75. The gas cell body contains a small droplet of alkali metal atoms (potassium, rubidium, or cesium) and a buffer gas and a quenching gas, nitrogen (N2). The alkali metal atoms are the core sensitive atoms of the magnetometer, used to sense changes in the external magnetic field; the buffer gas and quenching gas, nitrogen (N2), are used to suppress electron spin depolarization and increase relaxation time. The gas handle 75 is a hollow cylinder with a micropore for the passage of alkali metal atoms, buffer gas, and quenching gas. The oven is made of weakly magnetic aluminum nitride or boron nitride material, which provides thermal insulation between the alkali metal chamber 7 and the environment, increasing the temperature stability and uniformity of the alkali metal chamber. The heating film is composed of orderly arranged double-plane copper wires and is attached to two sides of the oven. The heating film is driven by a high-frequency (hundreds of kHz) current signal, heating the alkali metal chamber 7 to a preset temperature. A platinum resistance thermometer is also attached to the oven for real-time temperature monitoring. The detected temperature is then used for real-time temperature control via a program to maintain the temperature inside the chamber within ±0.03℃ of the preset temperature, enhancing the system's temperature stability.

[0046] The optical path assembly includes a laser 1, a polarization-maintaining fiber 2, a collimator 3, a polarizer 4, a quarter-wave plate 5, a first reflecting mirror 8, a second reflecting mirror 9, a third reflecting mirror 10, a first pump light 61, a second pump light 62, a third pump light 63, and a fourth pump light 64. The laser 1 is a DBR / DFB / VCSEL laser, etc., providing a light source for the magnetometer. The wavelength of the laser 1 is the D1 line of alkali metal atoms. The polarization-maintaining fiber 2 guides the light generated by the laser 1 into the magnetic shielding barrel 17. The collimator 3 collimates the light guided by the polarization-maintaining fiber 2. The light collimated by the collimator 3 becomes linearly polarized light after passing through the polarizer 4. The quarter-wave plate 5 converts the linearly polarized light into circularly polarized pump light 6. The circularly polarized pump light 6, after first passing along the z-axis through the first light-transmitting surface 71 of the alkali metal gas chamber 7, becomes the first pump light 61. The first pump light 61, after passing through the second light-transmitting surface 72 of the alkali metal gas chamber 7, passes through the first reflector 8 and then passes through the alkali metal gas chamber 7 a second time along the x-axis, becoming the second pump light 62. The second pump light 62, after passing through the third light-transmitting surface 73 of the alkali metal gas chamber 7, passes through the second reflector 9 and then passes through the alkali metal gas chamber 7 a third time along the z-axis, becoming the third pump light 63. The third pump light 63, after passing through the fourth light-transmitting surface 74 of the alkali metal gas chamber 7, passes through the third reflector 10 and then passes through the alkali metal gas chamber 7 a fourth time along the x-axis, becoming the fourth pump light 64. The first reflector 8, the second reflector 9, and the third reflector 10 are planar reflectors. The first reflector 8 is parallel to the second light-transmitting surface 72 of the alkali metal gas chamber 7; the second reflector 9 is parallel to the third light-transmitting surface 73 of the alkali metal gas chamber 7; and the third reflector 10 is parallel to the fourth light-transmitting surface 74 of the alkali metal gas chamber 7. The first pump light 61 is not incident perpendicularly to the first light-transmitting surface 71 of the alkali metal gas chamber 7, but rather at a 45° angle relative to the first light-transmitting surface 71. Similarly, the second pump light 62 is not incident perpendicularly to the second light-transmitting surface 72 of the alkali metal gas chamber 7, but rather at a 45° angle relative to the second light-transmitting surface 72. Likewise, the third pump light 63 is not incident perpendicularly to the third light-transmitting surface 73 of the alkali metal gas chamber 7, but rather at a 45° angle relative to the third light-transmitting surface 73.

[0047] Based on the response of alkali metal atoms to external magnetic fields using spin polarization, the first pump light 61 propagating along the z-axis can measure the magnetic fields along the x-axis and y-axis with high sensitivity; the second pump light 62 propagating along the x-axis can measure the magnetic fields along the y-axis and z-axis with high sensitivity; the third pump light 63 propagating along the z-axis can measure the magnetic fields along the x-axis and y-axis with high sensitivity; and the fourth pump light 64 propagating along the x-axis can measure the magnetic fields along the y-axis and z-axis with high sensitivity. Specifically, when the pump axis is along the z-axis, the evolution of atomic spin polarization dynamics can be described by the Bloch equation:

[0048]

[0049] Where P is the electronic spin polarizability of the alkali metal atom; q(P) is the nuclear slowing factor, ranging from 4 to 6; γ e =2π×28Hz / nT is the gyromagnetic ratio of the exposed electrons; B is the total magnetic field; R op s is the optical pumping rate caused by the pump light; s is the circular polarization vector of the pump light photon; R is a unit quantity along the z-axis. rel The relaxation rate is excluding the pump rate.

[0050] When a modulation field B is applied simultaneously along three axes:

[0051]

[0052] The spin polarization in the first pump light 61 along the z-axis can be approximated as:

[0053]

[0054] Similarly, the spin polarization of the second pump light 62 along the x-axis, the third pump light 63 along the z-axis, and the fourth pump light 64 along the x-axis can be approximately solved as follows:

[0055]

[0056] A single pump light contains the spin polarization information of the above four processes, that is, the total spin polarization information is... Therefore, highly sensitive synchronous measurement of the triaxial magnetic field can be achieved by detecting the pump light passing through the alkali metal gas chamber 7 for the fourth time.

[0057] The signal detection assembly includes a photodetector 11, a transimpedance amplifier 12, a lock-in amplifier 13, and a data acquisition unit 14.

[0058] The photodetector 11 is used to detect the pump light that has passed through the alkali metal gas cell 7 for the fourth time and convert the optical signal into a current signal. The transimpedance amplifier 12 is connected to the photodetector 11 and is used to amplify the current signal into a voltage signal. The lock-in amplifier 13 is used to extract the triaxial magnetic field response signal from the voltage signal output by the transimpedance amplifier 12, realizing simultaneous measurement of the triaxial magnetic field. The data acquisition unit 14 is connected to the lock-in amplifier 13 and is used to acquire the demodulated signal from the lock-in amplifier.

[0059] The active and passive magnetic compensation components include a signal generator 15, a triaxial magnetic coil 16, and a magnetic shielding barrel 17.

[0060] The magnetic shielding barrel 17 consists of four layers of μ-metal and one layer of aluminum alloy cylinder, used for actively shielding the ambient magnetic field. The triaxial magnetic coil 16 is fixed to a structure supported by PEEK material (polyetheretherketone resin) and placed at the center of the magnetic shielding barrel 17. It is used to generate the DC magnetic field, modulation magnetic field, and calibration magnetic field required by the triaxial magnetometer. The DC magnetic field is used to compensate for the residual magnetic field of the triaxial magnetometer, the modulation magnetic field is used to enable the magnetometer to operate in modulation mode, and the calibration magnetic field is used to self-calibrate the magnetometer to ensure the accuracy of the measured magnetic field. The DC and AC signals generated by the signal generator 15 are used to drive the triaxial magnetic coil 16.

[0061] Example 2

[0062] refer to Figure 3 An alkali metal gas cell 7 based on pump light multipath reflection of a triaxial SERF atomic magnetometer includes a gas cell body and a gas handle 75. The gas cell body is a cube. The gas handle 75 is connected to one face of the cube, and the four light-transmitting surfaces, namely the first light-transmitting surface 71, the second light-transmitting surface 72, the third light-transmitting surface 73, and the fourth light-transmitting surface 74, are all perpendicular to the face of the cube to which the gas handle 75 is connected.

[0063] Contents not described in detail in this specification are prior art known to those skilled in the art. It is hereby indicated that the above description is intended to help those skilled in the art understand this invention, but does not limit the scope of protection of this invention. Any equivalent substitutions, modifications, improvements, and / or simplifications of the above descriptions that do not depart from the essential content of this invention fall within the scope of protection of this invention.

Claims

1. A triaxial SERF atomic magnetometer based on pump light multi-path reflection, characterized in that, The device includes an alkali metal gas cell with a square cross-section. The square cross-section is perpendicular to the y-axis, the line connecting the first opposite vertices of the square cross-section is parallel to the z-axis, and the line connecting the second opposite vertices of the square cross-section is parallel to the x-axis. The upper left side of the square cross-section is the pump light incident side. A first reflecting mirror is attached to the upper right side of the square cross-section, a second reflecting mirror is attached to the lower right side, and a third reflecting mirror is attached to the lower left side. The pump light, after incident along the z-axis on the upper left side, forms a beam within the alkali metal gas cell that reaches the upper right side. The first reflector reflects the first pump light along the x-axis into a second pump light that reaches the lower right second reflector. The second reflector reflects the second pump light along the z-axis into a third pump light that reaches the lower left third reflector. The third reflector reflects the third pump light along the x-axis into a fourth pump light that reaches the upper left pump light incident side. The fourth pump light exits from the upper left side along the x-axis and passes sequentially through a photodetector, a transimpedance amplifier, and a lock-in amplifier to connect to the data acquisition unit.

2. The triaxial SERF atomic magnetometer based on pump light multi-path reflection according to claim 1, characterized in that, The alkali metal gas chamber is located inside the oven, the oven is located inside the triaxial magnetic coil, the triaxial magnetic coil is located inside the magnetic shielding barrel, and the triaxial magnetic coil is connected to the signal generator.

3. The triaxial SERF atomic magnetometer based on pump light multi-path reflection according to claim 1, characterized in that, The pump light comes from a laser, which is connected to the upper left pump light incident side in sequence through a polarization-maintaining fiber, a collimator, a polarizer, and a quarter-wave plate.

4. The triaxial SERF atomic magnetometer based on pump light multi-path reflection according to claim 3, characterized in that, The laser is a distributed Bragg reflector, a distributed feedback laser, or a vertical cavity surface-emitting laser.

5. The triaxial SERF atomic magnetometer based on pump light multi-path reflection according to claim 2, characterized in that, The oven is made of aluminum nitride or boron nitride. A heating film is attached to the surface of the oven. The heating film is made of double-plane copper wires arranged in an orderly manner. A platinum resistance thermometer is attached to the oven.

6. The triaxial SERF atomic magnetometer based on pump light multi-path reflection according to claim 1, characterized in that, Including the following expressions: Where P all It is the total spin polarization. It is the spin polarization in the first stroke of the pump light along the z-axis. It is the spin polarization in the second path of the pump light along the x-axis. It is the spin polarization in the third stroke pump light along the z-axis. It is the spin polarization in the fourth path of the pump light along the x-axis.

7. The triaxial SERF atomic magnetometer based on pump light multi-path reflection according to claim 6, characterized in that, Including the following expressions: in J0 is the optical pumping rate of the first path pump light along the z-axis, J1 is the zeroth-order Bessel function, and γ is the first-order Bessel function. e It is the electron gyromagnetic ratio, B x0 It is the remanence along the x-axis. It is the x-axis modulation frequency, and t is time. B is the relaxation rate in the pump light during the first stroke along the z-axis. y0 It is y-axis remanence. It is the y-axis modulation frequency; It is the optical pumping rate of the pump light along the second path of the x-axis. B is the relaxation rate in the second stroke of the pump light along the x-axis. z0 It is z-axis remanence. It is the z-axis modulation frequency; It is the optical pumping rate of the pump light along the third path of the z-axis. It is the relaxation rate in the pump light along the third stroke of the z-axis; It is the optical pumping rate of the pump light along the fourth path of the x-axis. It is the relaxation rate in the pump light along the fourth path along the x-axis.

Images