Method for detecting light polarization effect of SERF atomic spin gyroscope

Abstract

The invention relates to an optical polarization effect detection method of an SERF atomic spin gyroscope, which comprises the following steps: selecting an experimental device for detection, and adopting a K-3He-based atomic spin system, 2, starting a pumping light path, and carrying out polarization operation on two gases in an atomic gas chamber to realize transmission from electronic angular momentum to nuclear spin angular momentum; 3, a detection light path is started, and light signals are detected; and 4, applying monopulse disturbance of an alternating magnetic field in the y direction, enabling K atoms to deflect at a small angle, generating Larmor precession, keeping a strong coupling effect of K and 3He atoms, performing linear fitting on precession frequencies of the K atoms under different main magnetic fields, calculating the electron spin polarizability according to a slope value of the linear fitting, and calculating the electron spin polarizability according to the slope value of the linear fitting. And calculating an equivalent magnetic field generated by nuclear spinning by using an intercept value when an applied main magnetic field value is 0, and detecting direct and indirect polarization effects of the pumping light on the two atoms by using the slope and the intercept value. According to the invention, the effects of light direct polarization atoms and indirect polarization atoms are presented in a linear numerical fitting mode.

Description

Technical Field

[0001] The invention belongs to the technical field of inertial measurement, and in particular relates to a method for detecting the optical polarization effect of a SERF atomic spin gyroscope. Background Art

[0002] The research history of atomic spin gyroscopes is relatively long, dating back to 1973, when Happer et al. found that when the atomic density is large enough and the external magnetic field of the atoms is small enough, so that the spin exchange relaxation rate between atoms exceeds the Larmor frequency of the atomic energy level splitting, the spin exchange relaxation broadening will disappear, that is, it will reach a state without spin exchange relaxation, which can be explained by the principle of "motional narrowing". In 2005, researchers at Princeton University completed the first generation of new atomic spin gyroscopes based on the SERF principle. The gyroscope sensitive meter consists of a spherical gas chamber with a diameter of 25 mm, in which alkali metal atoms K, inert gases 3He and N2 are placed. In 2009, the research team developed the second generation SERF atomic spin gyroscope research platform, adding new designs such as mechanical vibration isolation platform, large vacuum environment, and low-noise magnetic shielding to improve the long-term stability of the gyroscope. ONERA The French Aerospace Lab began to develop SERF atomic spin gyroscopes based on Rb-129Xe in 2013. Honeywell's research team conducted research on chip-level SERF atomic spin gyroscopes and designed the corresponding structure and process implementation methods.

[0003] In 2008, Beijing University of Aeronautics and Astronautics took the lead in conducting SERF gyroscope research, using Cs-129Xe atomic source to build SERF gyroscopes, and experimentally verified the gyro effect in 2012. In order to improve the accuracy of gyroscopes, the K-Rb-21Ne atomic source mixed pumping method was selected for research, and a gyroscope prototype was developed. In 2016, the first SERF gyroscope ground speed measurement in China was achieved. In addition, Southeast University, Beijing Institute of Aerospace Control Instruments, and China Shipbuilding Industry Corporation 707 Institute have also carried out SERF gyroscope-related research.

[0004] The SERF atomic spin gyroscope makes use of the electron spin of alkali metal atoms and the nuclear spin of inert gases. Figure 1As shown, by manipulating the electron spin of alkali metal atoms to work in the SERF state, angular motion is measured. The SERF atomic spin gyroscope requires that both the electron spin and the nuclear spin have a macroscopic polarization direction. Through the spin exchange optical pumping technology, the pumping laser easily interacts with the electron spin of the alkali metal atom, and polarizes the electron spin by transferring the angular momentum of the photon to the electron spin, thereby giving it a macroscopic direction. And with the help of the electron spin of the alkali metal atom, the nuclear spin of the inert gas is polarized, so that the photon polarizes the electron spin, and the angular momentum is transferred to the nuclear spin, and finally the hyperpolarization of the nuclear spin is achieved. In the entire polarization process, the polarizability is an important indicator parameter for evaluating the effect of light polarization of atoms, and it is also one of the key factors affecting the dynamic range of the SERF atomic spin gyroscope.

[0005] At present, no effective method for testing the polarizability of light has been found in the prior art. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention proposes a method for detecting the optical polarization effect of a SERF atomic spin gyroscope.

[0007] The above-mentioned object of the present invention is achieved by the following technical solutions:

[0008] A method for detecting the light polarization effect of a SERF atomic spin gyroscope comprises the following steps:

[0009] Step 1: Select an experimental device for testing. The experimental device adopts a K-based 3 The atomic spin system of He, the main components of the system include: pumping light path part, detection light path part, magnetic shielding tube, three-dimensional compensation coil, atomic gas chamber and heating and insulation system; the atomic gas chamber adopts a spherical glass gas chamber, the pumping light path part includes a seed light source and a TA amplifier, which are used to polarize the two atomic gases in the atomic gas chamber; the detection light path part includes a linearly polarized light source, a beam splitter after passing through the gas chamber and a dual-path differential light detector; the three-dimensional compensation coil surrounds the atomic gas chamber, and is used to generate an alternating pulsed magnetic field with adjustable frequency and amplitude, the z direction is the main magnetic field direction, the x direction is the detection light direction, and the y direction is the sensitive axis direction.

[0010] Step 2: Based on the K- 3 The atomic spin system of He opens the pumping light path and performs polarization operations on the two gases in the atomic gas chamber, thus realizing the transfer of electron angular momentum to nuclear spin angular momentum.

[0011] Step 3: Based on the K- 3 He's atomic spin system opens the detection light path to detect optical signals.

[0012] Step 4: Apply a single pulse disturbance of the alternating magnetic field in the y direction to deflect the K atom by a small angle, generate Larmor precession, and keep K and 3 The strong coupling effect of He atoms is measured. The precession frequency of K atoms under different main magnetic fields is linearly fitted. The slope of the linear fit is used to calculate the electron spin polarization rate. The intercept value when the main magnetic field value is 0 is used to calculate the equivalent magnetic field generated by the nuclear spin. The slope and intercept values ​​are used to detect the direct and indirect polarization effects of the pumping light on the two atoms.

[0013] Moreover, in step 1, the atomic gas chamber is filled with N 2 steam.

[0014] Moreover, in step 2, a circularly polarized pump seed light source is used to output a light beam, the diameter of the light beam is about 5 mm, the wavelength of the light beam is selected at the first resonant wavelength of the K atom 770 nm, and the light power of the light beam is adjusted to more than 200 mW after passing through the TA amplifier. The power-amplified light beam is injected into the atomic gas chamber along the z direction, and after a 12-hour polarization process, the transfer of electronic angular momentum to nuclear spin angular momentum is realized.

[0015] Moreover, in step 3, the spot diameter of the linearly polarized detection light source output is 5 mm and the wavelength is 766 nm.

[0016] Moreover, in step 4, the linear fitting formula of the precession frequency of K atoms under different main magnetic fields is:

[0017] y=kx+b

[0018] Where y represents the frequency value, x represents the magnitude of the main magnetic field, and the slope k is the gyromagnetic ratio of the alkali metal atom γ = γ e / Q,γ e =28Hz / nT is the electron gyromagnetic ratio of alkali metal atoms, which is constant; Q represents the slowing factor, which affects the electron gyromagnetic ratio through the alkali metal nucleus; the value of Q depends on the polarization state of the ensemble, ranging from Q=6 at ultra-low polarization to Q=4 at saturation polarization; Q is related to the electron spin polarization rate P e The expression is:

[0019]

[0020] The slope k is used to determine the slowing factor Q and the electron spin polarization P. e To solve;

[0021] The intercept b is the frequency component when the applied main magnetic field value is 0. At this time, the atomic gas chamber is only affected by the equivalent magnetic field generated by the mutual coupling between the alkali metal atoms and the inert gas atoms:

[0022]

[0023] Among them, κ 0 This is because the electron wave function of the K atom is 3 The spin exchange enhancement factor generated by the overlap of He nuclei, κ at a fixed temperature 0 is a constant; the magnetization density M = μn corresponds to a magnetic moment of μ 0 , a polarized sample with an atomic density of n; the comprehensive equivalent magnetic field of the interaction between alkali metal atoms and inert gas atoms is:

[0024]

[0025] Among them, M n for 3 He atomic magnetization density, M e is the magnetization density of K atom, λ is the intrinsic coefficient of magnetic moment, and They are 3 Polarizability of He and K atoms;

[0026] The value of the comprehensive equivalent magnetic field is equivalent to 3 The equivalent magnetic field of He on K atoms is expressed by the intercept b and the gyromagnetic ratio γ of K atoms. e The ratio of B n Size, yes 3 The polarizability of He is used to determine the K atom pair 3 Detection of He polarization effect.

[0027] The advantages and positive effects of the present invention are:

[0028] 1. The light polarization effect detection method of the SERF atomic spin gyroscope designed by the present invention uses a three-dimensional compensation coil outside the atomic gas chamber to apply a single pulse perturbation of the excitation magnetic field in the y direction to the gas chamber, so that the electron spin of the alkali metal gas atom leaves the upper state of the Bloch sphere and deflects at a small angle, and at the same time stimulates Larmor precession, and the precession frequency value of the corresponding alkali metal gas atom is measured without disturbing the inert gas atoms. By linearly fitting the frequency values ​​under different longitudinal main magnetic fields, the electronic gyromagnetic ratio of the alkali metal gas atoms is calibrated with the fitting slope, and the accurate electron spin polarization rate is determined, thereby judging the effect of light on the polarization of the alkali metal atoms. The equivalent magnetic field generated by the inert gas atoms is calibrated with the fitting intercept to determine the indirect polarization effect of the alkali metal gas atoms on the inert gas atoms.

[0029] 2. The y-direction single-pulse magnetic field perturbation method designed by the present invention for measuring the electron spin polarization rate and the nuclear spin equivalent magnetic field can realize the intuitive detection of the polarization effect of the pumping light system on the atomic gas chamber in the SERF atomic spin gyroscope under the premise of maintaining the strong coupling between the alkali metal gas atoms and the inert gas atoms, and present the effects of the direct and indirect polarization of the two atoms by linear numerical fitting. The working principle is clear, the structure is simple, and the test efficiency is high. It can provide an important evaluation method and reference basis for the optical parameter effect of the SERF atomic spin gyroscope. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the basic principle diagram of the SERF atomic spin gyroscope; 1a is the working state of the SERF atomic spin gyroscope when it remains stationary, and 1b is the working state of the SERF atomic spin gyroscope when it rotates;

[0031] Figure 2 Based on K- 3 Schematic diagram of the setup of He SERF atomic spin gyroscope;

[0032] In the figure: 1. Seed light source; 2. TA amplifier; 3. Linearly polarized light source; 4. Magnetic shielding tube; 5. Three-dimensional compensation coil; 6. Heating and insulation system; 7. Atomic gas chamber; 8. Beam splitter; 9. Reflector; 10. Photoelectric balance detector; 11. Oscilloscope.

[0033] Figure 3 It is the linear fitting result of measuring the precession frequency of K atoms by applying a single pulse magnetic field in the y direction under two optical power conditions of the present invention. DETAILED DESCRIPTION

[0034] The structure of the present invention is further described below with reference to the accompanying drawings and by way of examples. It should be noted that the present examples are descriptive rather than restrictive.

[0035] Figure 1This is the basic schematic diagram of the SERF atomic spin gyroscope. Applying an external magnetic field B can cause the atomic spin to produce Larmor precession with a frequency ω: ω=γ|B|, where the gyro magnetic ratio γ can be used as a conversion factor between frequency and field strength. The atoms are polarized by optical pumping, and the photon angular momentum is transferred from a beam of circularly polarized light tuned to the atomic resonance frequency to a collection of atoms. A linearly polarized light beam propagating in a direction orthogonal to the pump beam is used to detect atomic polarization. When the probe beam passes through the alkali metal vapor, its polarization plane rotates along this direction at an angle proportional to the spin component. The SERF atomic spin gyroscope uses the strong coupling of the nuclear spins of inert gas atoms with the electronic spins of alkali metal atoms under specific conditions. The nuclear spins of inert gas atoms can automatically track and compensate for changes in the external magnetic field, thereby isolating the influence of the external magnetic field B on the fixed axis of the electronic spins of alkali metal atoms, and ultimately can measure angular motion, such as Figure 1 When the carrier rotates, the electron spin of the alkali metal atom keeps a fixed axis, and the detection laser is fixed on the carrier and rotates with the carrier. The angle between the detection laser and the electron spin reflects the rotation of the carrier relative to the inertial space.

[0036] Based on the basic working principle of the above-mentioned SERF atomic spin gyroscope, the present invention proposes a method for detecting the optical polarization effect of the SERF atomic spin gyroscope, wherein the pumping light transfers the photon angular momentum to the electronic angular momentum of the alkali metal gas atoms, thereby realizing the macroscopic polarization direction of the electron spin in the alkali metal atoms, and the polarization effect of the alkali metal gas atoms can be judged by the electron spin polarization rate. At the same time, the electron spin of the alkali metal atom can polarize the nuclear spin of the inert gas, thereby realizing the macroscopic polarization direction of the nuclear spin. During this process, the two atoms collide and strongly couple, and at the same time, the inert gas atoms generate an equivalent magnetic field to the alkali metal gas atoms, and the equivalent magnetic field value can reflect the magnitude of the nuclear spin polarization rate, so the polarization effect of the inert gas atoms can be judged by the equivalent magnetic field generated by the nuclear spin. After applying a single pulse excitation magnetic field perturbation in the y direction to the atomic gas chamber, the electron spin polarization rate and the equivalent magnetic field size can be measured, thereby judging the direct and indirect polarization effects of the pumping light system on the atomic gas chamber.

[0037] The technical solution adopted by the present invention is as follows:

[0038] A method for detecting the light polarization effect of a SERF atomic spin gyroscope comprises the following steps:

[0039] Step 1: Select an experimental device for testing. The experimental device adopts a K-based 3The atomic spin system of He, the main components of the system include: a pumping optical path part, a detection optical path part, a magnetic shielding tube 4, a three-dimensional compensation coil 5, an atomic gas chamber 7 and a heating and insulation system 6. The atomic gas chamber is a spherical glass gas chamber with a diameter of 1 cm. The pumping optical path part used to polarize the atomic gas chamber includes a seed light source 1 and a TA amplifier 2. The detection optical path part includes a linearly polarized light source 3, a beam splitter 8 after passing through the gas chamber, and a dual-path differential light detector, wherein the dual-path differential light detector includes a reflector 9, a photoelectric balance detector 10, and an oscilloscope 11. The three-dimensional compensation coil can provide the atomic gas chamber with alternating magnetic fields of different frequencies and sizes in the three-dimensional direction. Applying a pulsed magnetic field with a small angle in the y direction can measure the equivalent magnetic field generated by the electron spin polarization rate and the nuclear spin, thereby detecting the light polarization effect.

[0040] In the preparation of the atomic gas cell, any non-uniform area in the gas cell will produce first-order and higher-order gradients in the magnetic field, so that the electron spins will precess at different rates in the decoherent magnetic field gradient. The biggest source of non-uniform areas in the gas cell is the pull-off stem during the gas cell production process. This effect is mitigated by blocking the pull-off stem with a drop of metallic potassium. Using K vapor as the alkali metal atomic gas, 3 As an inert gas, He vapor has a much higher density than K vapor. On the one hand, it can be used as a high-pressure inert buffer gas to fill the atomic gas chamber, inhibit the diffusion of K vapor, and prevent the alkali metal spins from being depolarized immediately after colliding with the glass wall of the gas chamber. On the other hand, 3 The nuclear spin of He atoms can automatically track and compensate for changes in the external magnetic field, isolating the influence of the external magnetic field on the fixed axis of the electron spin of alkali metal atoms and achieving a gyro effect. 2 steam to quench the excited electrons in the K atom steam, and to stimulate N 2 The rotation state of the K atom is used to eliminate the orbital angular momentum of the K atom and return it to the ground state.

[0041] Fix the atomic gas chamber on the corresponding mounting structure. The schematic diagram of the device principle is as follows: Figure 2 As shown. The three-dimensional compensation coil surrounds the atomic gas chamber and can generate an alternating pulsed magnetic field with adjustable frequency and amplitude. The z direction is the main magnetic field direction, the x direction is the detection light direction, and the y direction is the sensitive axis direction. The longitudinal direction z corresponds to the main magnetic field, which determines the precession frequency of the atomic spin, which is generally a stable DC value. The transverse direction x corresponds to the direction of the detection light, and the transverse direction y corresponds to the direction of the gyroscope's sensitive axis of rotation. By applying the frequency and magnitude of a single pulse magnetic field in the y direction, the deflection angle of the alkali metal atomic electron spin quantum state can be adjusted. In the present invention, the spin precession of only the alkali metal atomic gas is achieved while maintaining the strong coupling influence of the alkali metal gas atoms and the inert gas atoms.

[0042] Step 2: Based on the K- 3 The atomic spin system of He opens the pumping optical path and performs polarization operation on the two gases in the atomic gas chamber, thus realizing the transfer of electronic angular momentum to nuclear spin angular momentum;

[0043] In this embodiment, a circularly polarized pump seed light source is used to output a light beam, the diameter of the light beam is about 5 mm, the wavelength of the light beam is selected at the first resonant wavelength of the K atom 770 nm, and the optical power of the light beam is adjusted to more than 200 mW after passing through the TA amplifier. The amplified light beam is injected into the atomic gas chamber along the z direction.

[0044] After 12 hours of polarization process, the pumping light path uses circularly polarized light to gradually produce direct and indirect polarization on the two atoms. This process gradually pumps the electrons in the ground state of the alkali metal atoms to the excited state. As the number of electrons accumulates, the angular momentum of the circularly polarized photons is converted into electron angular momentum. The nuclear spin of the inert gas atom and the electron spin of the alkali metal atom produce exchange collisions and strong coupling, realizing the transfer of electron angular momentum to nuclear spin angular momentum.

[0045] Step 3: Based on the K- 3 The atomic spin system of He is turned on the detection light path to detect the optical signal. In the embodiment of the present invention, the diameter of the output spot of the linearly polarized detection light is about 5 mm, and the wavelength is selected to be 766 nm while being far away from the resonant wavelength of the K atom to ensure that the optical signal is the strongest. The detection light is injected into the atomic gas chamber along the x direction. Due to the Faraday rotation effect produced by the atomic vapor after being polarized by the pumping light, the polarization plane of the linearly polarized detection light rotates after passing through the atomic gas chamber, and after being split by a 1:1 beam splitter, the light intensity is incident on the photoelectric balance detector to realize the detection of the optical signal.

[0046] Step 4: Detect the light polarization effect

[0047] By changing the main magnetic field of the three-dimensional compensation coil, a single pulse perturbation of the alternating magnetic field is applied in the y direction to deflect the atoms from the upper state of the Bloch sphere. The frequency and amplitude of the magnetic field pulse are changed to control the deflection angle. 3 He atom, so the magnetic field value required to deflect the quantum state of K atom is smaller, and the frequency and amplitude of the magnetic field pulse in the y direction are controlled to make the K atom deflect at a small angle, thereby producing precession. The precession frequency of the corresponding main magnetic field can be detected. At this time, the quantum state of He atom in Bloch sphere remains unchanged, that is, the strong coupling state of the two atoms is maintained.

[0048] The precession frequency of K atoms under different main magnetic fields is linearly fitted, such as Figure 3 As shown, the linear formula can be obtained:

[0049] y=kx+b.

[0050] Where y represents the frequency value, x represents the magnitude of the main magnetic field, and the slope k represents the gyromagnetic ratio of the alkali metal atom γ = γ e / Q,γ e =28Hz / nT represents the electron gyromagnetic ratio of alkali metal atoms, which is constant; Q represents the slowing factor, which affects the electron gyromagnetic ratio through the alkali metal nucleus. For K atoms, the value of Q depends on the polarization state of the ensemble, ranging from ultra-low polarization (P e =0) of Q = 6 to saturation polarization (P e =1) Q = 4. Slowdown factor Q and electron spin polarization P e The expression is:

[0051]

[0052] Therefore, the slope k can be used to calculate the slowing factor Q and the electron spin polarization rate P e Further, the intercept b represents the frequency component when the applied main magnetic field value is 0, at which time the atomic gas chamber is only affected by the equivalent magnetic field generated by the mutual coupling between the alkali metal atoms and the inert gas atoms:

[0053]

[0054] where κ 0 This is because the electron wave function of the K atom is 3 The spin exchange enhancement factor generated by the overlap of He nuclei, κ at a fixed temperature 0 is a constant. The magnetization density M = μn corresponds to a magnetic moment of μ 0 , a polarized sample with an atomic density of n, although 3 The magnetic moment of He is much smaller than that of K, but due to 3 The high atomic density n of He vapor, its magnetic density M n The magnetic density M of K atoms e The comprehensive equivalent magnetic field of the interaction between the two is

[0055]

[0056] The value of the comprehensive equivalent magnetic field is approximately equal to 3 The equivalent magnetic field of He on K atoms is due to 3 Nuclear spin polarizability of He Due to the influence of various relaxation mechanisms, it is impossible to solve directly. Therefore, the intercept b and the K atomic gyromagnetic ratio γ can be used. e The ratio of B n size, thus 3 The polarizability of He is used to determine the K atom pair3 Detection of He polarization effect.

[0057] In the embodiment of the present invention, after the pumping light power is stabilized at 200mW, the polarization is carried out for 12 hours, and a single pulse disturbance of an alternating magnetic field is applied in the y direction. The measurement results are as follows: Figure 3 The slope value k = 7.0393 Hz / nT represents the gyromagnetic ratio of the alkali metal atom γ = γ e / Q(γ e =28Hz / nT), Q≈4, at which point the electron spin polarization rate P of the alkali metal atom K e ≈1, proving that the pumping at this optical power produces complete polarization on the K atom. The intercept value b = -556.93 Hz, corresponding to the K atom feeling in a 0 magnetic field environment 3 The equivalent magnetic field exerted by the He atom is B n =-79.56nT, and by Can be mapped to noble gases 3 Nuclear spin polarizability of He atoms The strength of K atoms 3 Polarization detection of He atoms.

[0058] In order to conduct a comparative experiment when the effect of light-polarized atoms is weak, the TA is adjusted to stabilize the pumping light power at 20mW and then polarized for 12 hours. A single pulse magnetic field in the y direction is applied and the measurement is performed as described above. The results are as follows: Figure 3 As shown, Q≈5.3 is obtained, at which point the electron spin polarization rate P of the alkali metal atom K is e ≈0.46, which proves that the pumping at this optical power produces incomplete polarization on K atoms, while the corresponding 3 The equivalent magnetic field of He atoms is also small, which is B n =-16.17nT, proving that low power pump light is 3 The indirect polarization effect of He atoms is also weak. In summary, the slope and intercept of the linear fitting can be used to reflect the influence of the pump light on K atoms and 3 The direct and indirect polarization effects of He atoms make it possible to measure the optical polarization of the SERF atomic spin gyroscope by using a small-angle single-pulse magnetic field perturbation in the y direction.

[0059] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A method for detecting the light polarization effect of a SERF atomic spin gyroscope, characterized in that: The steps include: Step 1: Select an experimental device for testing. The experimental device adopts a K-based 3 The atomic spin system of He, the main components of which include: a pumping optical path part, a detection optical path part, a magnetic shielding tube, a three-dimensional compensation coil, an atomic gas chamber and a heating and heat preservation system; the atomic gas chamber adopts a spherical glass gas chamber, the pumping optical path part includes a seed light source and a TA amplifier, which are used to polarize the two atomic gases in the atomic gas chamber; the detection optical path part includes a linearly polarized light source, a beam splitter after passing through the gas chamber, and a dual-path differential optical detector; the three-dimensional compensation coil surrounds the atomic gas chamber, and is used to generate an alternating pulsed magnetic field with adjustable frequency and amplitude, the z direction is the main magnetic field direction, the x direction is the detection light direction, and the y direction is the sensitive axis direction; Step 2: Based on the K- 3 The atomic spin system of He opens the pumping optical path and performs polarization operation on the two gases in the atomic gas chamber, thus realizing the transfer of electronic angular momentum to nuclear spin angular momentum; Step 3: Based on the K- 3 The atomic spin system of He opens the detection optical path to detect the optical signal; Step 4: Apply a single pulse disturbance of the alternating magnetic field in the y direction to deflect the K atom by a small angle, generate Larmor precession, and keep K and 3 The strong coupling effect of He atoms is measured. The precession frequency of K atoms under different main magnetic fields is linearly fitted. The slope of the linear fit is used to calculate the electron spin polarization rate. The intercept value when the main magnetic field value is 0 is used to calculate the equivalent magnetic field generated by the nuclear spin. The slope and intercept values ​​are used to detect the direct and indirect polarization effects of the pumping light on the two atoms.

2. The method for detecting the light polarization effect of the SERF atomic spin gyroscope according to claim 1, characterized in that: In step 1, the atomic gas chamber is filled with N2 vapor.

3. The method for detecting the light polarization effect of the SERF atomic spin gyroscope according to claim 1, characterized in that: In step 2, a circularly polarized pump seed light source is used to output a beam with a diameter of about 5 mm. The wavelength of the beam is selected at the first resonant wavelength of the K atom, 770 nm. After the beam passes through the TA amplifier, the optical power is adjusted to more than 200 mW. The amplified beam is injected into the atomic gas chamber along the z direction. After a 12-hour polarization process, the transfer of electron angular momentum to nuclear spin angular momentum is achieved.

4. The method for detecting the light polarization effect of the SERF atomic spin gyroscope according to claim 1, characterized in that: In step 3, the spot diameter of the linearly polarized detection light source output is 5 mm and the wavelength is 766 nm.

5. The method for detecting the light polarization effect of the SERF atomic spin gyroscope according to claim 1, characterized in that: In step 4, the linear fitting formula of the K atom precession frequency under different main magnetic fields is: y=kx+b Among them, y represents the frequency value, x represents the main magnetic field, and the slope k is the gyromagnetic ratio of the alkali metal atom γ=γ e / Q,γ e =28Hz / nT is the electron gyromagnetic ratio of alkali metal atoms, which is constant; Q represents the slowing factor, which affects the electron gyromagnetic ratio through the alkali metal nucleus; the value of Q depends on the polarization state of the ensemble, ranging from Q=6 at ultra-low polarization to Q=4 at saturation polarization; Q is related to the electron spin polarization rate P e The expression is: The slope k is used to determine the slowing factor Q and the electron spin polarization P. e To solve; The intercept b is the frequency component when the applied main magnetic field value is 0. At this time, the atomic gas chamber is only affected by the equivalent magnetic field generated by the mutual coupling between the alkali metal atoms and the inert gas atoms: Among them, κ0 is due to the electron wave function of K atom and 3 The spin exchange enhancement factor generated by the overlap of He nuclei is constant at a fixed temperature. The magnetization density M = μn corresponds to a polarized sample with a magnetic moment of μ0 and an atomic density of n. The comprehensive equivalent magnetic field of the interaction between alkali metal atoms and inert gas atoms is: Among them, M n for 3 He atomic magnetization density, M e is the magnetization density of K atom, λ is the intrinsic coefficient of magnetic moment, and They are 3 Polarizability of He and K atoms; The value of the comprehensive equivalent magnetic field is equivalent to 3 The equivalent magnetic field of He on K atoms is expressed by the intercept b and the gyromagnetic ratio γ of K atoms. e The ratio of B n Size, yes 3 The polarizability of He is used to determine the K atom pair 3 Detection of He polarization effect.

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