An in-situ suppression device and method for optical coupling of an atomic magnetometer

Abstract

This invention discloses an in-situ suppression device and method for optical coupling of an atomic magnetometer. The method includes: S1, deploying the in-situ suppression device for optical coupling of the atomic magnetometer; S2, performing magnetic field modulation in the y-axis direction; S3, adjusting the DC current value of the precision current source until the first harmonic component is eliminated; S4, performing magnetic field modulation in the x-axis direction; S5, adjusting the DC current value of the precision current source until the first harmonic component is eliminated; S6, repeating S2 to S5 three times to obtain three sets of DC magnetic field compensation values, and calculating a. x and a y Step 7, according to a x and a y By using a reflector to adjust the propagation direction of the pump light, optical coupling caused by the non-orthogonality of the pump and detection lights can be suppressed. The solution described in this invention can measure and suppress optical coupling in atomic magnetometers caused by poor orthogonality and polarization of the pump and detection lights due to installation process and beam quality, thereby reducing measurement errors in the sensitive direction of the atomic magnetometer and improving magnetic field measurement sensitivity.

Description

Technical Field

[0001] This invention belongs to the field of magnetically sensitive atomic sensor technology, and particularly relates to an in-situ suppression device and method for optical coupling of an atomic magnetometer. Background Art

[0002] In the field of space remote sensing, atomic magnetometers possess extremely high sensitivity for magnetic field measurement and can be used for magnetic anomaly detection, geomagnetic exploration, deep space exploration, and planetary soil magnetic analysis, showing broad development prospects. Atomic magnetometers typically employ a two-beam configuration with orthogonal circularly polarized pump light and linearly polarized detection light. The pump light is used to polarize the alkali metal atoms within the sensitive core of the atomic magnetometer, aligning their spins. When an external magnetic field is present, the spin polarization direction deviates from its original direction. The detection light detects this spin deflection, thereby obtaining magnetic field information.

[0003] During the deployment and installation of an atomic magnetometer, poor orthogonality and polarization can occur due to installation techniques and beam quality, resulting in optical coupling. This mainly includes the non-orthogonal projection component of the pump light onto the detection light direction, and the pump effect caused by the ellipticity of the detection light. These optical couplings cause measurement errors in the sensitive direction of the atomic magnetometer, reducing its sensitivity, and necessitate in-situ suppression. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide an in-situ suppression scheme for optical coupling of an atomic magnetometer. By reducing the non-orthogonal projection component of the pump light in the direction of the detection light and the pump effect caused by the ellipticity of the detection light, the optical coupling caused by poor orthogonality and polarization due to the installation process and beam quality is suppressed, thereby improving the measurement sensitivity and accuracy of the atomic magnetometer.

[0005] To address the aforementioned technical problems, this invention discloses an in-situ suppression device for optical coupling of an atomic magnetometer, comprising: a magnetic shielding device and an atomic magnetometer; the atomic magnetometer comprises: a three-dimensional coil, an atomic magnetometer sensitive core, a precision current source, an oscilloscope, a photodetector, a pump light source, a detection light source, a reflector, and a polarizer;

[0006] A precision current source, an oscilloscope, a pump light source, and a detection light source are located outside the magnetic shielding device; the pump light source is located along the z-axis of the magnetic shielding device, and the detection light source is located along the x-axis of the magnetic shielding device; the oscilloscope is connected to the precision current source and the photodetector respectively; the precision current source is connected to the three-dimensional coil.

[0007] The three-dimensional coil, the sensitive core of the atomic magnetometer, the photodetector, the reflector, and the polarizer are arranged inside the magnetic shielding device. The three-dimensional coil is located at the center of the magnetic shielding device; the sensitive core of the atomic magnetometer is located at the center of the three-dimensional coil; the reflector is arranged in the z-axis direction of the magnetic shielding device, between the pump light source and the sensitive core of the atomic magnetometer; the polarizer is arranged in the x-axis direction of the magnetic shielding device, between the detection light source and the sensitive core of the atomic magnetometer; and the photodetector is arranged in the x-axis direction of the magnetic shielding device, on the side of the sensitive core of the atomic magnetometer away from the polarizer.

[0008] In the aforementioned in-situ suppression device for optical coupling of the atomic magnetometer

[0009] The magnetic shielding device is used to suppress the influence of external magnetic field disturbances on the working performance of the atomic magnetometer. In conjunction with the three-dimensional coil driven by a precision current source, it provides the sensitive core of the atomic magnetometer with the weak magnetic field environment required for the atomic magnetometer to maintain a spin-free exchange relaxation state.

[0010] A precision current source is used to generate three control currents to drive a three-dimensional coil to actively apply uniform magnetic fields with known amplitude and frequency in the x, y and z axes to actively compensate for the DC magnetic field.

[0011] Pump light source, used to provide pump light in the z-axis direction;

[0012] A reflector is used to adjust the direction of propagation of the pump light;

[0013] A detection light source is used to provide detection light in the x-axis direction;

[0014] Polarizers are used to adjust the ellipticity of the detection light.

[0015] The atomic magnetometer's sensitive core is used for highly sensitive measurement of the magnetic field components in the three orthogonal directions of x, y, and z. The sensitive core is made of an alkali metal atom gas cell containing alkali metal atoms. The alkali metal atoms are pumped and polarized along the z-axis, and their spin angular momentum is detected by a detection light along the x-axis.

[0016] A photodetector is used to convert the received detection light into an output signal from an atomic magnetometer and output it to an oscilloscope.

[0017] An oscilloscope is used to perform waveform or spectrum analysis on the received output signal from an atomic magnetometer.

[0018] In the aforementioned in-situ suppression device for optical coupling of the atomic magnetometer, the output signal of the atomic magnetometer is proportional to the component of the spin angular momentum of the alkali metal atom in the sensitive core of the atomic magnetometer in the x-axis direction.

[0019] In the above-mentioned in-situ suppression device for optical coupling of atomic magnetometer, the magnetic shielding device is made of magnetic shielding material, and after demagnetization treatment, the residual magnetism at the center is ≤5nT.

[0020] In the aforementioned in-situ suppression device for optical coupling of the atomic magnetometer, the three-dimensional coil includes: an x-axis uniform field coil, a y-axis uniform field coil, and a z-axis uniform field coil; wherein the x-axis uniform field coil, the y-axis uniform field coil, and the z-axis uniform field coil are respectively connected to a precision current source.

[0021] Accordingly, the present invention also discloses an in-situ suppression method for optical coupling of an atomic magnetometer based on the above-mentioned device, comprising:

[0022] Step 1: Deploy the in-situ suppression device for optical coupling of the atomic magnetometer;

[0023] Step 2, perform magnetic field modulation in the y-axis direction: use a precision current source to drive the three-dimensional coil to apply a low-frequency AC magnetic field in the y-axis direction, while maintaining a DC magnetic field in the x-axis and z-axis directions; measure the atomic magnetometer output signal A in the current state using a photodetector, and output the atomic magnetometer output signal A to an oscilloscope for waveform or spectrum analysis;

[0024] Step 3: Adjust the DC current value of the precision current source to drive the three-dimensional coil to actively compensate for the DC magnetic field. Observe the output signal A of the atomic magnetometer when the magnetic field is modulated in the y-axis direction until the first harmonic component in the output signal A of the atomic magnetometer in the oscilloscope is eliminated.

[0025] Step 4, perform magnetic field modulation in the x-axis direction: use a precision current source to drive the three-dimensional coil to apply a low-frequency AC magnetic field in the x-axis direction, while maintaining a DC magnetic field in the y-axis and z-axis directions; measure the atomic magnetometer output signal B in the current state using a photodetector, and output the atomic magnetometer output signal B to an oscilloscope for waveform or spectrum analysis;

[0026] Step 5: Adjust the DC current value of the precision current source to drive the three-dimensional coil to actively compensate for the DC magnetic field. Observe the output signal B of the atomic magnetometer when the magnetic field is modulated in the x-axis direction until the first harmonic component in the output signal B of the atomic magnetometer in the oscilloscope is eliminated.

[0027] Step 6: Repeat steps 2-5 three times to obtain three sets of DC magnetic field compensation values; based on the three sets of DC magnetic field compensation values, calculate the pump light components 'a' in the x-axis and y-axis directions. x and a y ;

[0028] Step 7, calculate a x and a y By using a mirror to adjust the propagation direction of the pump light, optical coupling caused by the non-orthogonality of the pump light and the detection light can be suppressed.

[0029] In the above method, the low-frequency AC magnetic field applied in the y-axis direction in step 2 has the same amplitude and frequency as the low-frequency AC magnetic field applied in the x-axis direction in step 4; wherein, the amplitude of the low-frequency AC magnetic field is <5nT, and the corresponding dimensionless parameter is β. m The frequency ω of the low-frequency alternating magnetic field is less than 5 Hz.

[0030] In the above method, in step 2, the dimensionless parameters corresponding to the DC magnetic fields in the x-axis and z-axis directions are β, respectively. x0 and β z0 Considering the DC magnetic field along the y-axis, β during modulation y =β y0 +β m sin(ωt); where β y β represents the dimensionless parameter corresponding to the resultant magnetic field in the y-axis direction. y0 denoted by dimensionless parameter corresponding to the DC magnetic field in the y-axis direction, and t represents the modulation time.

[0031] In the above method, in step 4, the dimensionless parameters corresponding to the DC magnetic fields in the y-axis and z-axis directions are β, respectively. y0 and β z0 Considering the DC magnetic field along the x-axis, β during modulation x =β x0 +β m sin(ωt); where β x β represents the dimensionless parameter corresponding to the resultant magnetic field in the x-axis direction. x0 The dimensionless parameter represents the DC magnetic field in the x-axis direction, and t represents the modulation time.

[0032] In the above method, steps 2 to 5 are repeated three times to obtain three sets of DC magnetic field compensation values; based on the three sets of DC magnetic field compensation values, the components 'a' of the pump light in the x-axis and y-axis directions are calculated. x and a y ,include:

[0033] During the repetition of steps 2-5 three times, a set of DC magnetic field compensation values ​​in three directions is obtained in each repetition, and the corresponding dimensionless parameters are as follows: and In each repetition, a set of DC magnetic field compensation values ​​in three directions can be obtained to eliminate the first harmonic component;

[0034] and satisfy:

[0035]

[0036] To simplify the calculations, in steps 3 and 5, when adjusting the DC current value of the precision current source to drive the three-dimensional coil to actively compensate for the DC magnetic field, the parameters of the precision current source are set so that... Then we have:

[0037]

[0038] Where, ΔB x0 express and The difference, ΔB y0 express and The difference.

[0039] The present invention has the following advantages:

[0040] (1) This invention discloses an in-situ suppression scheme for optical coupling of an atomic magnetometer, which can measure and suppress the optical coupling caused by poor orthogonality and polarization of pump and detection light in the atomic magnetometer due to installation process and beam quality, thereby reducing the measurement error in the sensitive direction of the atomic magnetometer and improving the magnetic field measurement sensitivity.

[0041] (2) This invention discloses an in-situ suppression scheme for optical coupling of an atomic magnetometer. All the components required in the implementation of the scheme are the components of the atomic magnetometer itself, without the need to add additional components. This can achieve in-situ suppression of optical coupling and is conducive to miniaturization applications.

[0042] (3) This invention discloses an in-situ suppression scheme for optical coupling of an atomic magnetometer. Although the atomic magnetometer needs to work in a spin-free exchange relaxation state, its devices and configurations are applicable to a variety of atomic magnetometers. After optical suppression, the magnetometer parameters can be adjusted in-situ to switch to other working states. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the structure of an in-situ suppression device for optical coupling of an atomic magnetometer according to an embodiment of the present invention;

[0044] Figure 2 This is a flowchart of an in-situ suppression method for optical coupling of an atomic magnetometer according to an embodiment of the present invention. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments disclosed in the present invention will be described in further detail below with reference to the accompanying drawings.

[0046] Reference Figure 1In this embodiment, the in-situ optical coupling suppression device for the atomic magnetometer includes: a magnetic shielding device 1 and an atomic magnetometer; further, the atomic magnetometer includes: a three-dimensional coil 2, an atomic magnetometer sensitive core 3, a precision current source 4, an oscilloscope 5, a photodetector 6, a pump light source 7, a detection light source 8, a reflector 9, and a polarizer 10. The precision current source 4, oscilloscope 5, pump light source 7, and detection light source 8 are disposed outside the magnetic shielding device 1; the pump light source 7 is disposed in the z-axis direction of the magnetic shielding device 1, and the detection light source 8 is disposed in the x-axis direction of the magnetic shielding device 1; the oscilloscope 5 is connected to the precision current source 4 and the photodetector 6 respectively; the precision current source 4 is connected to the three-dimensional coil 2. The three-dimensional coil 2, the atomic magnetometer sensitive core 3, the photodetector 6, the reflector 9, and the polarizer 10 are arranged inside the magnetic shielding device 1; the three-dimensional coil 2 is located at the center of the magnetic shielding device 1; the atomic magnetometer sensitive core 3 is located at the center of the three-dimensional coil 2; the reflector 9 is arranged in the z-axis direction of the magnetic shielding device 1, between the pump light source 7 and the atomic magnetometer sensitive core 3; the polarizer 10 is arranged in the x-axis direction of the magnetic shielding device 1, between the detection light source 8 and the atomic magnetometer sensitive core 3; the photodetector 6 is arranged in the x-axis direction of the magnetic shielding device 1, on the side of the atomic magnetometer sensitive core 3 away from the polarizer 10.

[0047] In this embodiment, the magnetic shielding device 1 is used to suppress the influence of external magnetic field disturbances on the working performance of the atomic magnetometer. It works in conjunction with the three-dimensional coil 2 driven by the precision current source 4 to provide the sensitive core 3 of the atomic magnetometer with the weak magnetic field environment required for the atomic magnetometer to maintain a spin-free exchange relaxation state. The precision current source 4 generates three control currents to drive the three-dimensional coil 2 to actively apply uniform magnetic fields of known amplitude and frequency in the x, y, and z axes to actively compensate for the DC magnetic field. The pump light source 7 provides pump light 71 in the z-axis direction. The reflector 9 adjusts the propagation direction of the pump light 71. The detection light source 8 provides detection light 81 in the x-axis direction. The polarizer 10 adjusts the ellipticity of the detection light 81. The atomic magnetometer's sensitive core 3 is used for highly sensitive measurement of the magnetic field components in the three orthogonal directions of x, y, and z. The sensitive core 3 is made of an alkali metal atom gas chamber containing alkali metal atoms. These alkali metal atoms are polarized by a pump light 71 along the z-axis and their spin angular momentum is detected by a detection light 81 along the x-axis. A photodetector 6 converts the received detection light 81 into an atomic magnetometer output signal and outputs it to an oscilloscope 5. The oscilloscope 5 is used for waveform or spectrum analysis of the received atomic magnetometer output signal.

[0048] In this embodiment, the output signal of the atomic magnetometer is proportional to the component of the spin angular momentum of the alkali metal atoms in the sensitive core 3 of the atomic magnetometer along the x-axis. The magnetic shielding device 1 is made of magnetic shielding material, and after demagnetization treatment, the residual magnetism at the center is ≤5nT. The three-dimensional coil 2 mainly includes: an x-axis uniform field coil, a y-axis uniform field coil, and a z-axis uniform field coil; the x-axis uniform field coil, the y-axis uniform field coil, and the z-axis uniform field coil are respectively connected to the precision current source 4.

[0049] In this embodiment, based on the above-mentioned in-situ suppression device for optical coupling of atomic magnetometer, the present invention also discloses an in-situ suppression method for optical coupling of atomic magnetometer.

[0050] like Figure 2 As shown, the in-situ suppression method for optical coupling of the atomic magnetometer includes:

[0051] Step 1: Deploy the in-situ suppression device for optical coupling of the atomic magnetometer.

[0052] In this embodiment, the in-situ suppression device for optical coupling of the atomic magnetometer can be referred to the description in the above embodiment, and will not be repeated here.

[0053] With the sensitive core 3 of the atomic magnetometer as the origin, the detection light is positioned along the x-axis, and the atomic magnetometer is maintained in a spin-free relaxation state through active and passive magnetic compensation. During operation, the output signal of the atomic magnetometer is proportional to the atomic spin angular momentum component along the x-axis where the detection light is located. The evolution of the atomic spin angular momentum within the atomic magnetometer is as follows:

[0054]

[0055] Where S represents the spin angular momentum vector of the atomic spin ensemble, B represents the magnetic field vector, and γ represents the gyromagnetic ratio of the atomic ensemble, γ = γ e / Q(P), where Q(P) represents the slowing factor, γ e γ represents the gyromagnetic ratio of electrons. e ≈2π×28Hz / nT, Q(P) and γ e All are considered constants; R represents the pump vector, used to characterize the laser pump effect. The components of R in the x, y, and z axes are respectively represented by R... x R y and R z Indicated; Δω represents the magnetic resonance linewidth, Δω=R tot / Q(P), R tot This represents the total relaxation rate of atomic spin.

[0056] The steady-state response S0 of the atomic ensemble spin angular momentum is mainly determined by the static magnetic field B0 and the pump vector R. Considering the static or slowly varying magnetic field response, we set the dimensionless magnetic field parameter β = γ. eB / R tot Simplify the calculation, β x β y and β z Let β be the components of β in the x, y, and z axes.

[0057] Ideally, the pump beam should be positioned along the z-axis. However, considering factors such as installation errors, poor detection beam quality, and ellipticity, the actual pump beam is primarily along the z-axis, but it has projection components in the x and y-axis directions. This results in an equivalent small-angle pump component in the detection beam direction, with corresponding angles α. x and a y Then: sina x ≈a x sina y ≈a y cosa x ≈1, cosa y ≈1, that is, the pumping vector is R = R z [a x ,a y ,1] T The steady-state response in the direction of the detected light is actually:

[0058]

[0059] Among them, S 0z This represents the initial angular momentum in the z-axis direction of the steady-state response under no magnetic field conditions, which includes the response error term of optical coupling. It is necessary to eliminate a x and a y Suppress optical coupling.

[0060] Step 2, perform magnetic field modulation in the y-axis direction: use a precision current source 4 to drive the three-dimensional coil 2 to apply a low-frequency AC magnetic field (amplitude < 5nT, corresponding to the dimensionless parameter β) in the y-axis direction. m (Frequency ω < 5Hz), a DC magnetic field is maintained in the x-axis and z-axis directions, and the corresponding dimensionless parameters are β and β, respectively. x0 and β z0 Considering the DC magnetic field along the y-axis, β during modulation... y =β y0 +β m sin(ωt), β y β represents the dimensionless parameter corresponding to the resultant magnetic field in the y-axis direction. y0 The dimensionless parameter representing the DC magnetic field along the y-axis is denoted by t, which represents the modulation time. The atomic magnetometer output signal A in the current state is measured by photodetector 6, and then output to oscilloscope 5 for waveform or spectrum analysis.

[0061] In this embodiment, the output signal A of the atomic magnetometer is proportional to the steady-state response of the detection light direction, and the steady-state response is as follows:

[0062] S x ≈S 0z [β y0 +β x0 β z0 +a x (1+β x0 2 )+a y (-β z0 +β x0 β y0 )

[0063] +β m (1+a y β x0 sin(ωt)]

[0064] Step 3: Adjust the DC current value of the precision current source 4 to drive the three-dimensional coil 2 to actively compensate for the DC magnetic field. Observe the output signal A of the atomic magnetometer when the magnetic field is modulated in the y-axis direction until the first harmonic component in the output signal A of the atomic magnetometer in the oscilloscope 5 is eliminated.

[0065] Step 4, perform magnetic field modulation in the x-axis direction: use a precision current source 4 to drive the three-dimensional coil 2 to apply a low-frequency AC magnetic field (amplitude < 5nT, corresponding to the dimensionless parameter β) in the x-axis direction. m (Frequency ω < 5Hz), a DC magnetic field is maintained in the y-axis and z-axis directions, and the corresponding dimensionless parameters are β and β, respectively. y0 and β z0 Considering the DC magnetic field along the x-axis, β during modulation... x =β x0 +β m sin(ωt), β x β represents the dimensionless parameter corresponding to the resultant magnetic field in the x-axis direction. x0 This represents the dimensionless parameter corresponding to the DC magnetic field along the x-axis. The atomic magnetometer output signal B in the current state is measured by photodetector 6, and then output to oscilloscope 5 for waveform or spectrum analysis.

[0066] In this embodiment, the low-frequency AC magnetic field applied in the x-axis direction in this step is the same as the low-frequency AC magnetic field applied in the y-axis direction in step 2. The atomic magnetometer output signal B is proportional to the steady-state response in the direction of the detection light, and the steady-state response at this time is:

[0067] S x ≈S 0z [β y0 +β x0 βz0 +a x (1+β x0 2 +β m 2 / 2)+a y (-β z0 +β x0 β y0 )

[0068] +(β z0 +2a x β x0 +a y β y0 )β m sin(ωt)

[0069] -a x β m 2 / 2cos(2ωt)]

[0070] As can be seen from the above equation, during the magnetic field modulation process along the x-axis, the second harmonic component of the atomic magnetometer output signal contains a small angular component α. x Information can be obtained by using an oscilloscope to perform waveform or frequency domain analysis on the output signal of the atomic magnetometer, which allows observation of the second harmonic component.

[0071] Step 5: Adjust the DC current value of the precision current source 4 to drive the three-dimensional coil 2 to actively compensate for the DC magnetic field. Observe the output signal B of the atomic magnetometer when the magnetic field is modulated in the x-axis direction until the first harmonic component in the output signal B of the atomic magnetometer in the oscilloscope 5 is eliminated.

[0072] Step 6: Repeat steps 2-5 three times to obtain three sets of DC magnetic field compensation values; based on the three sets of DC magnetic field compensation values, calculate the pump light components 'a' in the x-axis and y-axis directions. x and a y .

[0073] In this embodiment, due to the dimensionless parameter β corresponding to the DC magnetic field (static magnetic field) x0 β y0 β z0 It includes remanence and a compensated DC magnetic field in the x, y, and z axes, respectively. The existence of the compensated DC magnetic field can make β z0 +2a x β x0 +a y β y0 =0, meaning the first harmonic component in the output signal of the atomic magnetometer is zero, and the DC compensation magnetic field values ​​in the three directions are not unique.

[0074] During the repetition of steps 2-5 three times, a set of DC magnetic field compensation values ​​in three directions is obtained in each repetition (all of which can eliminate the first harmonic component). The corresponding dimensionless parameters are as follows: and

[0075] and satisfy:

[0076]

[0077] To simplify the calculation, in steps 2 and 4, when adjusting the DC current value of the precision current source 4 to drive the three-dimensional coil 2 to actively compensate for the DC magnetic field, the parameters of the precision current source 4 are set so that... Then we have:

[0078]

[0079] Where, ΔB x0 express and The difference, ΔB y0 express and The difference.

[0080] At this point, although the magnitudes of the remanent magnetism in the x, y, and z axes are unknown, the magnitude difference ΔB can be compensated by using a known precision current source to adjust the magnetic field. x0 ΔB y0 , Therefore, a can be calculated. x and a y .

[0081] Step 7, calculate a x and a y The direction of propagation of the pump light 7 is adjusted by using the reflector 9, thereby suppressing the optical coupling caused by the non-orthogonality of the pump light and the detection light.

[0082] In this embodiment, due to a x The polarization of the detection light is influenced by both the projection component of the pump light onto the direction of the detection light and the ellipticity of the detection light. Then, a polarizer is used to adjust the polarization of the detection light until the difference 'a' between the DC terms modulated in the x-axis and y-axis directions is reached. x β m 2 / 2 is zero (this difference is equal to the second harmonic amplitude of the response signal). At this point, the steady-state response signal no longer contains a second harmonic component, thus suppressing the optical coupling of the atomic magnetometer. That is, after suppressing optical coupling, the DC components of the steady-state response output signal should be the same when modulated in the x-axis and y-axis directions respectively. Using the method described above, optical coupling in a pump-detection orthogonal configuration of a dual-beam atomic magnetometer can be conveniently and in situ suppressed.

[0083] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

[0084] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. An in-situ suppression device for optical coupling of an atomic magnetometer, characterized in that, include: Magnetic shielding device (1) and atomic magnetometer; The atomic magnetometer includes: a three-dimensional coil (2), an atomic magnetometer sensitive core (3), a precision current source (4), an oscilloscope (5), a photodetector (6), a pump light source (7), a detection light source (8), a reflector (9), and a polarizer (10); A precision current source (4), an oscilloscope (5), a pump light source (7), and a detection light source (8) are arranged outside the magnetic shielding device (1); the pump light source (7) is arranged in the z-axis direction of the magnetic shielding device (1), and the detection light source (8) is arranged in the x-axis direction of the magnetic shielding device (1); the oscilloscope (5) is connected to the precision current source (4) and the photodetector (6) respectively; the precision current source (4) is connected to the three-dimensional coil (2); A three-dimensional coil (2), an atomic magnetometer sensitive core (3), a photodetector (6), a reflector (9), and a polarizer (10) are arranged inside a magnetic shielding device (1). The three-dimensional coil (2) is located at the center of the magnetic shielding device (1); the atomic magnetometer sensitive core (3) is located at the center of the three-dimensional coil (2); the reflector (9) is arranged in the z-axis direction of the magnetic shielding device (1), between the pump light source (7) and the atomic magnetometer sensitive core (3); the polarizer (10) is arranged in the x-axis direction of the magnetic shielding device (1), between the detection light source (8) and the atomic magnetometer sensitive core (3); and the photodetector (6) is arranged in the x-axis direction of the magnetic shielding device (1), on the side of the atomic magnetometer sensitive core (3) away from the polarizer (10).

2. The in-situ suppression device for optical coupling of an atomic magnetometer according to claim 1, characterized in that, The magnetic shielding device (1) is used to suppress the influence of external magnetic field disturbance on the working performance of the atomic magnetometer. It works in conjunction with the three-dimensional coil (2) driven by the precision current source (4) to provide the sensitive core (3) of the atomic magnetometer with the weak magnetic field environment required for the atomic magnetometer to maintain a spin-free exchange relaxation state. A precision current source (4) is used to generate three control currents to drive the three-dimensional coil (2) to actively apply uniform magnetic fields with known amplitude and frequency in the three directions of x-axis, y-axis and z-axis to actively compensate for the DC magnetic field. A pump light source (7) is used to provide pump light (71) in the z-axis direction; A reflector (9) is used to adjust the propagation direction of the pump light (71); A detection light source (8) is used to provide detection light (81) in the x-axis direction; Polarizer (10) is used to adjust the ellipticity of the detection light (81); The atomic magnetometer sensitive core (3) is used to measure the magnetic field components in the three orthogonal directions of x, y and z with high sensitivity; wherein, the atomic magnetometer sensitive core (3) is made of alkali metal atom gas chamber, which contains alkali metal atoms; the alkali metal atoms are polarized by pump light (71) along the z-axis and their spin angular momentum is detected by detection light (81) along the x-axis; A photodetector (6) is used to convert the received detection light (81) into an atomic magnetometer output signal and output it to an oscilloscope (5); An oscilloscope (5) is used to perform waveform or spectrum analysis on the received atomic magnetometer output signal.

3. The in-situ suppression device for optical coupling of an atomic magnetometer according to claim 2, characterized in that, The output signal of the atomic magnetometer is proportional to the component of the spin angular momentum of the alkali metal atom in the x-axis direction within the sensitive core (3) of the atomic magnetometer.

4. The in-situ suppression device for optical coupling of an atomic magnetometer according to claim 1, characterized in that, The magnetic shielding device (1) is made of magnetic shielding material, and after demagnetization treatment, the residual magnetism at the center is ≤5nT.

5. The in-situ suppression device for optical coupling of an atomic magnetometer according to claim 1, characterized in that, The three-dimensional coil (2) includes: an x-axis uniform field coil, a y-axis uniform field coil and a z-axis uniform field coil; wherein the x-axis uniform field coil, the y-axis uniform field coil and the z-axis uniform field coil are respectively connected to a precision current source (4).

6. A method for in-situ suppression of optical coupling in an atomic magnetometer based on the device described in claim 1, characterized in that, include: Step 1: Deploy the in-situ suppression device for optical coupling of the atomic magnetometer; Step 2, perform magnetic field modulation in the y-axis direction: use a precision current source (4) to drive the three-dimensional coil (2) to apply a low-frequency AC magnetic field in the y-axis direction, while maintaining a DC magnetic field in the x-axis and z-axis directions; measure the atomic magnetometer output signal A in the current state through a photodetector (6), and output the atomic magnetometer output signal A to an oscilloscope (5) for waveform or spectrum analysis; Step 3: Adjust the DC current value of the precision current source (4) to drive the three-dimensional coil (2) to actively compensate the DC magnetic field, and observe the output signal A of the atomic magnetometer when the magnetic field is modulated in the y-axis direction until the first harmonic component in the output signal A of the atomic magnetometer in the oscilloscope (5) is eliminated; Step 4, perform magnetic field modulation in the x-axis direction: use a precision current source (4) to drive the three-dimensional coil (2) to apply a low-frequency AC magnetic field in the x-axis direction, while maintaining a DC magnetic field in the y-axis and z-axis directions; measure the atomic magnetometer output signal B in the current state through a photodetector (6), and output the atomic magnetometer output signal B to an oscilloscope (5) for waveform or spectrum analysis; Step 5: Adjust the DC current value of the precision current source (4) to drive the three-dimensional coil (2) to actively compensate the DC magnetic field, and observe the output signal B of the atomic magnetometer when the magnetic field is modulated in the x-axis direction until the first harmonic component in the output signal B of the atomic magnetometer in the oscilloscope (5) is eliminated. Step 6: Repeat steps 2-5 three times to obtain three sets of DC magnetic field compensation values; based on the three sets of DC magnetic field compensation values, calculate the pump light components 'a' in the x-axis and y-axis directions. x and a y ; Step 7, calculate a x and a y The direction of the pump light (7) is adjusted by using a mirror (9) to suppress the optical coupling caused by the non-orthogonality of the pump light and the detection light.

7. The method according to claim 6, characterized in that, The low-frequency AC magnetic field applied in the y-axis direction in step 2 has the same amplitude and frequency as the low-frequency AC magnetic field applied in the x-axis direction in step 4; wherein, the amplitude of the low-frequency AC magnetic field is <5nT, and the corresponding dimensionless parameter is β. m The frequency ω of the low-frequency alternating magnetic field is less than 5 Hz.

8. The method according to claim 7, characterized in that, In step 2, the dimensionless parameters corresponding to the DC magnetic fields in the x-axis and z-axis directions are β and β, respectively. x0 and β z0 Considering the DC magnetic field along the y-axis, β during modulation y =β y0 +β m sin(ωt); where β y β represents the dimensionless parameter corresponding to the resultant magnetic field in the y-axis direction. y0 denoted by dimensionless parameter corresponding to the DC magnetic field in the y-axis direction, and t represents the modulation time.

9. The method according to claim 8, characterized in that, In step 4, the dimensionless parameters corresponding to the DC magnetic fields in the y-axis and z-axis directions are β and β, respectively. y0 and β z0 Considering the DC magnetic field along the x-axis, β during modulation x =β x0 +β m sin(ωt); where β x β represents the dimensionless parameter corresponding to the resultant magnetic field in the x-axis direction. x0 The dimensionless parameter represents the DC magnetic field in the x-axis direction, and t represents the modulation time.

10. The method according to claim 9, characterized in that, Repeat steps 2-5 three times to obtain three sets of DC magnetic field compensation values; based on the three sets of DC magnetic field compensation values, calculate the components 'a' of the pump light in the x-axis and y-axis directions. x and a y ,include: During the repetition of steps 2-5 three times, a set of DC magnetic field compensation values ​​in three directions is obtained in each repetition, and the corresponding dimensionless parameters are as follows: and In each repetition, a set of DC magnetic field compensation values ​​in three directions can be obtained to eliminate the first harmonic component; and satisfy: To simplify the calculation, in steps 3 and 5, when adjusting the DC current value of the precision current source (4) to drive the three-dimensional coil (2) to actively compensate for the DC magnetic field, the parameters of the precision current source (4) are set so that... Then we have: Where, ΔB x0 express and The difference, ΔB y0 express and The difference.

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