Single-fiber coupling type double-beam miniaturized high-sensitivity atom magnetometer device

Abstract

According to the single-fiber coupling type double-beam miniaturized high-sensitivity atom magnetometer device, pumping laser and detection laser are orthogonally coupled into a single polarization maintaining fiber through a polarization beam splitter, and miniaturization of a light source light path is achieved. Besides, the polarization maintaining optical fiber and the polarization beam splitter are adopted to combine and decouple the light beams, so that the problems that the miniaturization difficulty of the magnetometer probe is increased due to light guide of multiple collimating heads and extra noise is introduced by multiple optical fibers are avoided, and high sensitivity is realized in a small detection volume; and a great promotion effect is achieved in related detection application of high-density multi-atom magnetometer array type heart and brain magnetism.

Description

Technical Field

[0001] The present invention relates to the technical field of atomic magnetometers, and in particular to a single fiber-coupled dual-beam miniaturized high-sensitivity atomic magnetometer device, which orthogonally couples a pump laser and a detection laser into a single polarization-maintaining optical fiber through a polarization beam splitter to achieve miniaturization of the light source optical path. The method of combining and decoupling light beams using a polarization-maintaining optical fiber and a polarization beam splitter avoids the difficulty of miniaturizing the magnetometer probe due to multiple collimating heads and the introduction of additional noise by multiple optical fibers, and achieves high sensitivity in a small detection volume, which plays a great role in promoting the related detection applications of high-density multi-atom magnetometer array-type heart and brain magnetism. Background Art

[0002] Quantum sensing measurement equipment has brought progress in the fields of positioning, navigation, remote sensing, biomedicine, materials science, and basic physics, and has promoted the development of business and the application of science and technology with its detection accuracy and excellent sensitivity that surpass traditional classical sensors. Among them, the spin-exchange relaxation-free (SERF) atomic magnetometer achieves full suppression of spin exchange relaxation under high atomic density and low ambient magnetic field conditions, thereby greatly improving the sensitivity of magnetic field measurement. At present, SERF atomic magnetometers have been widely used in geomagnetic measurement, medical imaging and other fields.

[0003] Generally, single-beam atomic magnetometers are more popular in MCG (magnetocardiography) and MEG (magnetoencephalography) due to their more compact design, easier operation, and smaller integrated package. However, dual-beam magnetometers have many advantages, such as higher sensitivity and no need for magnetic field modulation. Dual-beam atomic magnetometers avoid the multi-channel crosstalk problem caused by magnetic field modulation in single-beam configurations and improve the positioning and calibration accuracy of array applications. All new atomic magnetometer sensitivity records are achieved by dual-beam magnetometers with pump-probe configurations. Therefore, the development of miniature dual-beam atomic magnetometers with pump-probe configurations may further improve the performance of MEG and MCG. In addition, power and wavelength optimization are easier to achieve. Based on this, the present invention proposes a high-sensitivity all-optical atomic magnetometer device based on miniaturization of single-fiber coupled dual-beam. Summary of the invention

[0004] The technical problem to be solved by the present invention is: to overcome the shortcomings of the prior art, to provide a single fiber-coupled dual-beam miniaturized high-sensitivity atomic magnetometer device, to orthogonally couple the pump laser and the detection laser into a single polarization-maintaining optical fiber through a polarization beam splitter, and to achieve miniaturization of the light source optical path. In addition, the method of combining and decoupling the light beams using polarization-maintaining optical fiber and a polarization beam splitter avoids the difficulty of miniaturizing the magnetometer probe due to the multi-collimation head light guide and the introduction of additional noise by multiple optical fibers, to achieve high sensitivity in a small detection volume, and to play a great role in promoting the related detection applications of high-density multi-atom magnetometer array-type heart and brain magnetism.

[0005] The technical solution of the present invention is as follows:

[0006] A single-fiber coupled dual-beam miniaturized high-sensitivity atomic magnetometer device is characterized in that it includes a third polarization-maintaining optical fiber, one end of which is connected to the photosynthesis system through a third optical fiber bracket and the other end is connected to the optical decoupling system through a collimator. The photosynthesis system combines the detection light and the pump light into a combined light beam, and the polarization direction of the detection light in the combined light beam is perpendicular to the polarization direction of the pump light and is orthogonally coupled into the third polarization-maintaining optical fiber. The optical decoupling system decouples the combined light beam into a detection light beam and a pump light beam, and the decoupled detection light and pump light pass through the alkali metal gas chamber in an orthogonal manner.

[0007] The detection light comes from a detection laser, which is an external cavity diode laser ECDL, and emits a D2 line detection beam. The pump light comes from a pump laser, which is a distributed feedback laser DFB, and emits a D1 line pump beam.

[0008] The detection laser is connected to the second input side of the first polarization beam splitter prism through the second polarization-maintaining fiber, the second fiber holder, the second λ / 2 wave plate and the first plane reflector in sequence; the pumping laser is connected to the first input side of the first polarization beam splitter prism through the first polarization-maintaining fiber, the first fiber holder and the first λ / 2 wave plate in sequence; the output side of the first polarization beam splitter prism that combines the pump light from the first input side with the detection light from the second input side is connected to the third polarization-maintaining fiber through the third plane reflector, the second plane reflector, the third λ / 2 wave plate, the first λ / 4 wave plate and the third fiber holder in sequence.

[0009] The input side of the second polarization beam splitter prism in the optical decoupling system is connected to the collimator, the transmission side of the second polarization beam splitter prism is connected to the first photodetector via the second λ / 4 wave plate and the alkali metal gas chamber in sequence, the reflection side of the second polarization beam splitter prism is connected to the input side of the third polarization beam splitter prism via the first right-angle reflector, the second right-angle reflector, the alkali metal gas chamber and the fourth λ / 2 wave plate in sequence, the transmission side of the third polarization beam splitter prism is connected to the first input end of the differential processor via the second photodetector, the reflection side of the third polarization beam splitter prism is connected to the second input end of the differential processor via the third photodetector, and the output end of the differential processor is connected to the data acquisition system.

[0010] The alkali metal gas chamber is located in a ceramic oven, the ceramic oven is located in a three-axis magnetic field coil, and the three-axis magnetic field coil is located in a magnetic shielding barrel.

[0011] The alkali metal gas chamber has a side length of 4 mm and is equipped with an enrichment 87 Rb atomic droplet; 700 Torr 4 He and 50 Torr N2 gas are placed in a quasi-static state with a shielding factor of at least 10 5 The five-layer μ metal shield.

[0012] The sensitivity is in the fT range.

[0013] Include the following expressions:

[0014]

[0015] θ∝P x Im[V(vv D2 )]=K y B y +C,

[0016]

[0017] Where Px is the electron spin polarization along the x direction; P0 is the intermediate quantity, ΔB is the intermediate quantity; B is the magnetic field, B y is the y-axis magnetic field, B x is the x-axis magnetic field, B z is the z-axis magnetic field, R op is the pump rate, Γpr is the absorption rate of photons from the probe light, T2 is the transverse relaxation time, g s is the electron spin factor, μ B is the gyromagnetic ratio, s is the polarization vector of the photon along the propagation direction, θ is the optical rotation angle; Im represents the imaginary part, V(vv D2 ) is the absorption line shape of the D2 line with respect to the optical frequency ν, ν D2 is the resonant frequency of the D2 transition; K yis the scaling factor and C is the scaling factor.

[0018] The advantages of the present invention compared with the prior art are:

[0019] (1) A single polarization-maintaining fiber pump-probe solution is adopted, and the pump beam and the probe beam share the optical axis, further simplifying the difficulty of miniaturization.

[0020] (2) By using an all-optical single polarization-maintaining fiber pump-probe OPM array, the crosstalk effect of magnetically modulated single-beam OPMs when they are too close to each other can be avoided, enabling potential high-resolution MEG recordings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of a single fiber-coupled dual-beam miniaturized high-sensitivity atomic magnetometer device according to the present invention. Figure 1 Included Figure 1 (a) Figure 1 (b) and Figure 1 (c). Figure 1 (a) is a schematic diagram of the photosynthetic beam system structure. Figure 1 (b) is a schematic diagram of the light path in polarization-maintaining optical fiber. Figure 1 (c) is a schematic diagram of the optical decoupling system structure. Figure 1 The invention comprises a light beam combining system and a light decoupling system. In the light beam combining system, the detection light (the light emitted by the detection laser 1, ECDL-external cavity diode laser) and the pump light (the light emitted by the pump laser 11, DFB-distributed feedback laser) are coupled to the third polarization-maintaining optical fiber 10 (single polarization-maintaining PM optical fiber) through the first polarization beam splitter prism 15, the first λ / 2 wave plate 14, the second λ / 2 wave plate 4, the first plane reflector 5, the third plane reflector 16, the second plane reflector 6, the third λ / 2 wave plate 7 and the first λ / 4 wave plate 8 to complete the light beam combining. In the light decoupling system, the combined light beam emitted from the optical fiber collimator (collimation head 19) is decoupled by the second polarization beam splitter prism 20. The single fiber coupled type dual beam miniaturized high-sensitivity all-optical atomic magnetometer operates in the SERF state, that is, it satisfies the extremely weak magnetic environment with high alkali metal atomic number density and close to zero. A method of combining and decoupling light beams using polarization-maintaining optical fiber and a polarization beam splitter can achieve high sensitivity in a small detection volume. The sensitivity of the single-fiber-coupled dual-beam miniaturized high-sensitivity all-optical atomic magnetometer device is in the fT order.

[0022] The reference numerals are as follows: 1-detection laser; 2-second polarization-maintaining fiber; 3-second fiber holder; 4-second λ / 2 wave plate; 5-first plane reflector; 6-second plane reflector; 7-third λ / 2 wave plate; 8-first λ / 4 wave plate; 9-third fiber holder; 10-third polarization-maintaining fiber; 11-pumping laser; 12-first polarization-maintaining fiber; 13-first fiber holder; 14-first λ / 2 wave plate; 15-first polarization splitter; 16-third plane reflector; 17-pumping laser Polarization direction; 18-detection light polarization direction; 19-collimator; 20-second polarization splitter prism; 21-first right-angle reflector; 22-second right-angle reflector; 23-ceramic oven; 24-first photodetector; 25-alkali metal gas chamber; 26-second λ / 4 wave plate; 27-fourth λ / 2 wave plate; 28-combined prism; 29-second photodetector; 30-third photodetector; 31-differential processor; 32-data acquisition system; 33-three-axis magnetic field coil; 34-magnetic shielding barrel. DETAILED DESCRIPTION

[0023] Below is the attached figure ( Figure 1 ) and Examples illustrate the present invention.

[0024] Figure 1 This is a schematic diagram of the structure of a single fiber-coupled dual-beam miniaturized high-sensitivity atomic magnetometer device according to the present invention. Figure 1 As shown, a single-fiber coupled dual-beam miniaturized high-sensitivity atomic magnetometer device includes a third polarization-maintaining optical fiber 10 connected to a photosynthesis system through a third optical fiber bracket 9 at one end and connected to a light decoupling system through a collimator 19 at the other end. The photosynthesis system combines detection light and pump light into a combined light beam, in which the polarization direction of the detection light (i.e., the detection light polarization direction 18) and the polarization direction of the pump light (i.e., the pump light polarization direction 17) are perpendicular to each other and are orthogonally coupled into the third polarization-maintaining optical fiber 10. The light decoupling system decouples the combined light beam into a detection light beam and a pump light beam, and the decoupled detection light and pump light pass through the alkali metal gas chamber 25 in an orthogonal manner.

[0025] The detection light comes from the detection laser 1, which is an external cavity diode laser ECDL. The detection laser 1 emits a D2 line detection beam. The pump light comes from the pump laser 11, which is a distributed feedback laser DFB, and emits a D1 line pump beam. The detection laser 1 is connected to the second input side of the first polarization beam splitter prism 15 through the second polarization-maintaining fiber 2, the second fiber bracket 3, the second λ / 2 wave plate 4 and the first plane reflector 5 in sequence. The pump laser 11 is connected to the first input side of the first polarization beam splitter prism 15 through the first polarization-maintaining fiber 12, the first fiber bracket 13 and the first λ / 2 wave plate 14 in sequence. The output side of the first polarization beam splitter prism 15, which combines the pump light from the first input side with the detection light from the second input side, is connected to the third polarization-maintaining fiber 10 through the third plane reflector 16, the second plane reflector 6, the third λ / 2 wave plate 7, the first λ / 4 wave plate 8 and the third fiber bracket 9 in sequence.

[0026] The input side of the second polarization beam splitter prism 20 in the optical decoupling system is connected to the collimator 19, the transmission side of the second polarization beam splitter prism 20 is connected to the first photodetector 24 through the second λ / 4 wave plate 26 and the alkali metal gas chamber 25 in sequence, the reflection side of the second polarization beam splitter prism 20 is connected to the input side of the combination prism 28 through the first right-angle reflector 21, the second right-angle reflector 22, the alkali metal gas chamber 25 and the fourth λ / 2 wave plate 27 in sequence, the transmission side of the combination prism 28 is connected to the first input end of the differential processor 31 through the second photodetector 29, the reflection side of the combination prism 28 is connected to the second input end of the differential processor 31 through the third photodetector 30, and the output end of the differential processor 31 is connected to the data acquisition system 32.

[0027] The alkali metal gas chamber 25 is located in the ceramic oven 23, the ceramic oven 23 is located in the three-axis magnetic field coil 33, and the three-axis magnetic field coil 33 is located in the magnetic shielding barrel 34. The alkali metal gas chamber 25 has a side length of 4 mm and is filled with enriched 87 Rb atomic droplet; 700 Torr 4 He and 50 Torr N2 gas are placed in a quasi-static state with a shielding factor of at least 10 5 The five-layer μ metal shield.

[0028] The sensitivity is in the fT range.

[0029] Include the following expressions:

[0030]

[0031] θ∝P x Im[V(vv D2 )]=Ky B y +C,

[0032]

[0033] Where Px is the electron spin polarization along the x direction; P0 is the intermediate quantity, ΔB is the intermediate quantity; B is the magnetic field, B y is the y-axis magnetic field, B x is the x-axis magnetic field, B z is the z-axis magnetic field, R op is the pump rate, Γpr is the absorption rate of photons from the probe light, T2 is the transverse relaxation time, g s is the electron spin factor, μ B is the gyromagnetic ratio, s is the polarization vector of the photon along the propagation direction, θ is the optical rotation angle; Im represents the imaginary part, V(vv D2 ) is the absorption line shape of the D2 line with respect to the optical frequency ν, ν D2 is the resonant frequency of the D2 transition; K y is the scaling factor and C is the scaling factor.

[0034] The present invention relates to a high-sensitivity all-optical atomic magnetometer device based on a single fiber-coupled dual-beam miniaturization. The pump laser and the detection laser are orthogonally coupled into a single polarization-maintaining optical fiber through a polarization beam splitter to achieve miniaturization of the light source optical path. The method of combining and decoupling the light beams using polarization-maintaining optical fiber and a polarization beam splitter avoids the difficulty of miniaturizing the magnetometer probe due to multiple collimating heads and the introduction of additional noise by multiple optical fibers, and achieves high sensitivity in a small detection volume, which plays a great role in promoting the related detection applications of high-density multi-atom magnetometer array-type heart and brain magnetism.

[0035] A high-sensitivity all-optical atomic magnetometer device based on a single fiber-coupled dual-beam miniaturization, characterized in that it includes a photosynthesis system and an optical decoupling system. In the photosynthesis system, the pump light and the probe light are coupled to a single polarization-maintaining (PM) optical fiber through a polarization beam splitter, a λ / 2 wave plate, and a λ / 4 wave plate to complete the beam combining. In the optical decoupling system, the combined beam emitted from the fiber collimator is decoupled by a polarization splitter. The single fiber-coupled dual-beam miniaturization high-sensitivity all-optical atomic magnetometer operates in a SERF state, that is, it satisfies an extremely weak magnetic environment with a high alkali metal atomic number density close to zero. The method of combining and decoupling the light beams using a polarization-maintaining optical fiber and a polarization beam splitter achieves high sensitivity in a small detection volume. The sensitivity of the single fiber-coupled dual-beam miniaturization high-sensitivity all-optical atomic magnetometer device is in the order of fT.

[0036] Furthermore, in the presence of high buffer gas pressure, the diffusion motion of atoms is greatly suppressed and the wall collision rate can be reduced. In this case, the diffusion term can be ignored. The steady-state solution of the output signal of the all-optical SERF atomic magnetometer can be obtained,

[0037]

[0038] in,

[0039] θ∝P x Im[V(vv D2 )]=K y B y +C

[0040] where V(ν) is the absorption line shape of the D2 line with respect to the optical frequency ν, ν D2 is the resonant frequency of the D2 transition. The proportionality factor K y and C is expressed as:

[0041] and

[0042] Furthermore, the alkali metal gas chamber has a side length of 4 mm and is equipped with an enrichment 87 Rb atomic droplet; 700 Torr 4 He and 50 Torr N2 gas are placed in a quasi-static state with a shielding factor of at least 10 5 In order to achieve high 87 The gas cell was heated to 418 K and the temperature was controlled using a closed-loop system. Three pairs of orthogonal Helmholtz coils were installed in the center of the interaction region to provide a uniform magnetic field.

[0043] Furthermore, the D1 line pump beam (795 nm) and the D2 line detection beam (780 nm) are respectively generated by a distributed feedback laser (DFB) with a linewidth of 500 MHz and an external cavity diode laser (ECDL) with a linewidth of 10 kHz.

[0044] The two D1 line pump light beams (795nm) and D2 line detection light beams (780nm) are overlapped through the first polarization beam splitter (PBS), and then sequentially pass through the first plane reflector, the second plane reflector, the third λ / 2 wave plate and the first λ / 4 wave plate of the optical device, and then are coupled into the third polarization-maintaining optical fiber through the third optical fiber holder. The detection light s component and the pump light s component correspond to the fast axis and the slow axis of the polarization-maintaining optical fiber (PMF) respectively. After passing through the PMF, the two light beams are collimated by a collimator and decoupled using a second polarization beam splitter, and then pass through the alkali metal gas chamber in an orthogonal manner.

[0045] Furthermore, the two beams are overlapped by a polarization beam splitter (PBS) and then coupled to a single polarization-maintaining fiber through an optical device, corresponding to the fast axis and slow axis of the polarization-maintaining fiber (PMF), respectively. After passing through the PMF, the two beams are collimated by a collimator and decoupled using a PBS, and then pass through the gas chamber in an orthogonal manner.

[0046] Furthermore, the second λ / 4 wave plate tunes the D1 line beam to circular polarization to generate spin polarization in the alkali metal gas cell. The alkali atoms in the alkali metal gas cell are pumped by the circularly polarized pump light of the D1 line, and the light intensity of the circularly polarized light is detected by the PD to perform three-axis magnetic compensation.

[0047] The linearly polarized light beam is mainly the detection light s component after decoupling by the second polarization beam splitter prism. Due to the imperfect device measurement, it carries part of the pump light s component. The detection of spin polarization is to detect the Faraday rotation of the D2 light beam by a balanced detector, and the linear polarization detection light is detected. The linear polarization is analyzed by a balanced detector, which is composed of a second photodetector, a third photodetector, and a fourth λ / 2 wave plate. The signal from the balanced detector is amplified by a first transimpedance amplifier. After the signal is amplified, the signal then enters the data acquisition system for synchronous demodulation.

[0048] The data acquisition system extracts useful signals from noise by comparing phases with reference signals, and significantly improves the sensitivity and selectivity of signals. The lock-in amplifier in the data acquisition system is used to synchronously demodulate and process the signals.

[0049] The pump laser and the detection laser are orthogonally coupled into a single polarization-maintaining optical fiber through a polarization beam splitter to achieve miniaturization of the light source optical path.

[0050] Furthermore, the linearly polarized light beam is used to detect spin polarization, and a balanced detector is used to detect the Faraday rotation of the D2 light beam, and the linearly polarized detection light is used for detection.

[0051] Further, the detected signal is amplified using a photodiode amplifier and then analyzed using a data acquisition system.

[0052] refer to Figure 1As shown, a high-sensitivity all-optical atomic magnetometer device based on a single fiber-coupled dual-beam miniaturization, a photosynthesis system and an optical decoupling system. In the photosynthesis system, the pump light emitted by the laser 11 and the detection light emitted by the laser 1 are coupled to a single polarization-maintaining (PM) optical fiber 10 through a λ / 2 wave plate 4, a λ / 2 wave plate 14, a polarization beam splitter 15, a reflector 5, a reflector 6, a reflector 16 and a λ / 4 wave plate 8 to complete the beam combining. In the optical decoupling system, the combined beam emitted from the fiber collimator 19 is decoupled by a polarization splitter 20. The single fiber-coupled dual-beam miniaturization high-sensitivity all-optical atomic magnetometer operates in a SERF state, that is, an extremely weak magnetic environment with a high alkali metal atomic density close to zero. A method of combining and decoupling light beams using polarization-maintaining optical fiber and a polarization beam splitter can achieve high sensitivity in a small detection volume. The sensitivity of the single-fiber-coupled dual-beam miniaturized high-sensitivity all-optical atomic magnetometer device is in the fT order.

[0053] The steady-state solution of the output signal of the all-optical SERF atomic magnetometer,

[0054]

[0055] in,

[0056] θ∝P x Im[V(vv D2 )]=K y B y +C

[0057] where V(ν) is the absorption line shape of the D2 line with respect to the optical frequency ν, ν D2 is the resonant frequency of the D2 transition. The proportionality factor K y and C is expressed as:

[0058] and

[0059] The alkali metal gas chamber 23 has a side length of 4 mm and is filled with enriched 87 Rb atomic droplet; 700 Torr 4 He and 50 Torr N2 gas are placed in a quasi-static state with a shielding factor of at least 10 5 In order to achieve high 87 Rb atomic density, the alkali metal gas chamber 23 is heated to 418K using a ceramic oven 22, and the temperature is controlled using a closed loop system. A triaxial magnetic field coil 33 is installed at the center of the interaction region to provide a uniform magnetic field.

[0060] The D1 line pump beam (795 nm) and the D2 line probe beam (780 nm) are generated by a distributed feedback laser (DFB) with a line width of 500 MHz and an external cavity diode laser (ECDL) with a line width of 10 kHz, respectively.

[0061] The two D1 line pump beams (795nm) and D2 line detection beams (780nm) are overlapped by the first polarization beam splitter (PBS) 15, and then sequentially pass through the first plane reflector 16, the second plane reflector 6, the third λ / 2 wave plate 7 and the first λ / 4 wave plate 8 of the optical device, and then are coupled into the third polarization-maintaining optical fiber 10 through the third optical fiber holder 9. After passing through the PMF 10, the two beams are collimated by the collimator 19 and decoupled using the second polarization beam splitter 20, and then pass through the alkali metal gas chamber 25 in an orthogonal manner.

[0062] The second λ / 4 wave plate 26 adjusts the D1 line light beam emitted from the collimator 19 to circular polarization to generate spin polarization in the alkali metal gas cell 25. The alkali atoms in the alkali metal gas cell 25 are pumped by the circularly polarized pump light of the D1 line, and the light intensity of the circularly polarized light is detected by the first photodetector 24 to perform three-axis magnetic compensation.

[0063] The linearly polarized light beam is mainly decoupled from the detection light by the second polarization beam splitter prism 20. The detection of spin polarization is performed by detecting the Faraday rotation of the D2 light beam through a balanced detector, and the linear polarization detection light is detected. The linear polarization is analyzed by a balanced detector, which is composed of a second photodetector 30, a third photodetector 29, and a fourth λ / 2 wave plate 27. The signal from the balanced detector is synchronously demodulated by entering the data acquisition system 32.

[0064] The data acquisition system 32 extracts the useful signal from the noise by comparing the phase with the reference signal, and significantly improves the sensitivity and selectivity of the signal. The lock-in amplifier in the data acquisition system 32 is used to synchronously demodulate and process the signal.

[0065] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in the field. It is pointed out here that the above description helps those skilled in the art to understand the invention, but does not limit the protection scope of the invention. Any equivalent replacement, modification and / or simplification of the above description without departing from the essence of the invention falls within the protection scope of the invention.

Claims

1. A single fiber-coupled dual-beam miniaturized high-sensitivity atomic magnetometer device, characterized in that: The invention comprises a third polarization-maintaining optical fiber, one end of which is connected to the optical beam combining system through a third optical fiber bracket and the other end of which is connected to the optical decoupling system through a collimator. The optical beam combining system combines the detection light and the pump light into a combined light beam, the polarization direction of the detection light in the combined light beam is perpendicular to the polarization direction of the pump light and they are orthogonally coupled into the third polarization-maintaining optical fiber. The optical decoupling system decouples the combined light beam into a detection light beam and a pump light beam, and the decoupled detection light and pump light pass through the alkali metal gas chamber in an orthogonal manner.

2. The single fiber coupled dual beam miniaturized high sensitivity atomic magnetometer device according to claim 1, characterized in that: The detection light comes from a detection laser, which is an external cavity diode laser ECDL, and emits a D2 line detection beam. The pump light comes from a pump laser, which is a distributed feedback laser DFB, and emits a D1 line pump beam.

3. The single fiber coupled dual beam miniaturized high sensitivity atomic magnetometer device according to claim 2, characterized in that: The detection laser is connected to the second input side of the first polarization beam splitter prism through the second polarization-maintaining fiber, the second fiber holder, the second λ / 2 wave plate and the first plane reflector in sequence; the pumping laser is connected to the first input side of the first polarization beam splitter prism through the first polarization-maintaining fiber, the first fiber holder and the first λ / 2 wave plate in sequence; the output side of the first polarization beam splitter prism that combines the pump light from the first input side with the detection light from the second input side is connected to the third polarization-maintaining fiber through the third plane reflector, the second plane reflector, the third λ / 2 wave plate, the first λ / 4 wave plate and the third fiber holder in sequence.

4. The single fiber coupled dual beam miniaturized high sensitivity atomic magnetometer device according to claim 1, characterized in that: The input side of the second polarization beam splitter prism in the optical decoupling system is connected to the collimator, the transmission side of the second polarization beam splitter prism is connected to the first photodetector via the second λ / 4 wave plate and the alkali metal gas chamber in sequence, the reflection side of the second polarization beam splitter prism is connected to the input side of the third polarization beam splitter prism via the first right-angle reflector, the second right-angle reflector, the alkali metal gas chamber and the fourth λ / 2 wave plate in sequence, the transmission side of the third polarization beam splitter prism is connected to the first input end of the differential processor via the second photodetector, the reflection side of the third polarization beam splitter prism is connected to the second input end of the differential processor via the third photodetector, and the output end of the differential processor is connected to the data acquisition system.

5. The single fiber coupled dual beam miniaturized high sensitivity atomic magnetometer device according to claim 1, characterized in that: The alkali metal gas chamber is located in a ceramic oven, the ceramic oven is located in a three-axis magnetic field coil, and the three-axis magnetic field coil is located in a magnetic shielding barrel.

6. The single fiber coupled dual beam miniaturized high sensitivity atomic magnetometer device according to claim 1, characterized in that: The alkali metal gas chamber has a side length of 4 mm and is equipped with an enrichment 87 Rb atomic droplet; 700 Torr 4 He and 50 Torr N2 gas are placed in a quasi-static state with a shielding factor of at least 10 5 The five-layer μ metal shield.

7. The single fiber coupled dual beam miniaturized high sensitivity atomic magnetometer device according to claim 1, characterized in that: The sensitivity is in the fT range.

8. The single fiber coupled dual beam miniaturized high sensitivity atomic magnetometer device according to claim 1, characterized in that: Include the following expressions: θ∝P x Im[V(v-v D2 )]=K y B y +C, Where Px is the electron spin polarization along the x direction; P0 is the intermediate quantity, ΔB is the intermediate quantity; B is the magnetic field, B y is the y-axis magnetic field, B x is the x-axis magnetic field, B z is the z-axis magnetic field, R op is the pump rate, Γpr is the absorption rate of photons from the probe light, T2 is the transverse relaxation time, g s is the electron spin factor, μ B is the gyromagnetic ratio, s is the polarization vector of the photon along the propagation direction, θ is the optical rotation angle; Im represents the imaginary part, V(vv D2 ) is the absorption line shape of the D2 line with respect to the optical frequency ν, ν D2 is the resonant frequency of the D2 transition; K y is the scaling factor and C is the scaling factor.

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