A method for detecting light polarization effect of a SERF atomic spin gyroscope

Abstract

The application relates to a light polarization effect detection method of a SERF atomic spin gyroscope. 3 The atomic spin system of He, 2, the pumping light path is turned on, polarization operation is carried out on the two kinds of gases in the atomic gas chamber, the transmission of the electron angular momentum to the nuclear spin angular momentum is realized; 3, the detection light path is turned on, and the light signal is detected; 4, a single pulse disturbance of an alternating magnetic field is applied in the y direction, the K atom is deflected at a small angle, the Larmor precession is generated, the K and 3 The strong coupling effect of He atoms, the precession frequency of the K atoms under different main magnetic fields is linearly fitted, the slope value of the linear fitting is used to calculate the electron spin polarization rate, the intercept value when the applied main magnetic field value is 0 is used to calculate the equivalent magnetic field generated by the nuclear spin, and the direct and indirect polarization effects of the pumping light on the two kinds of atoms are detected by the slope and the intercept value. The effects of the two kinds of atoms polarized directly and indirectly by light are presented in the form of linear numerical fitting.

Description

Technical Field

[0001] This invention belongs to the field of inertial measurement technology, and specifically relates to a method for detecting the optical polarization effect of a SERF atomic spin gyroscope. Background Technology

[0002] Research on atomic spin gyroscopes has a long history, dating back to 1973 when Happer et al. discovered that when the atomic density is sufficiently high and the external magnetic field around the atoms is sufficiently low, causing the spin exchange relaxation rate between atoms to exceed the Larmor frequency at which atomic energy levels split, the spin exchange relaxation broadening disappears, reaching a state without spin exchange relaxation. This phenomenon can be explained by the principle of "kinetic narrowing." In 2005, researchers at Princeton University completed the first generation of a novel atomic spin gyroscope based on the SERF principle. Its gyroscope sensor consists of a 25mm diameter spherical gas chamber containing alkali metal atoms (K), inert gases (3He and N2), etc. In 2009, the research group developed a second-generation SERF atomic spin gyroscope research platform, adding new designs such as a mechanical vibration isolation platform, a high-vacuum environment, and low-noise magnetic shielding to improve the long-term stability of the gyroscope. The French Aerospace Lab (ONERA) began developing SERF atomic spin gyroscopes based on Rb-129Xe in 2013. A research group at Honeywell conducted research on chip-scale SERF atomic spin gyroscopes, designing the corresponding structures and fabrication methods.

[0003] Beijing University of Aeronautics and Astronautics pioneered SERF gyroscope research in China in 2008, constructing a SERF gyroscope using a Cs-129Xe atomic source and experimentally verifying the gyroscopic effect in 2012. Subsequently, to improve gyroscope accuracy, a hybrid pumping method using K-Rb-21Ne atomic sources was selected for further research, resulting in the development of a gyroscope prototype. In 2016, China achieved the first-ever ground velocity measurement using a SERF gyroscope. In addition, Southeast University, Beijing Aerospace Control Instrument Research Institute, and the 707 Research Institute of China Shipbuilding Industry Corporation have also conducted related research on SERF gyroscopes.

[0004] The SERF atomic spin gyroscope combines the electron spin of alkali metal atoms with the nuclear spin of inert gases. Its principle is as follows: Figure 1As shown, angular motion is measured by manipulating the electron spins of alkali metal atoms to operate in the SERF state. SERF atomic spin gyroscopes require both electron and nuclear spins to have macroscopic polarization. Through spin-exchange optical pumping technology, the pump laser easily interacts with the electron spins of alkali metal atoms, transferring photon angular momentum to the electron spin, thus polarizing the electron spin and giving it macroscopic direction. Furthermore, by using the electron spins of alkali metal atoms to polarize the nuclear spins of the inert gas, photons polarize the electron spins, transferring angular momentum to the nuclear spins, ultimately achieving hyperpolarization of the nuclear spins. Throughout the polarization process, polarizability is an important parameter for evaluating the effect of optically polarized atoms and is also one of the key factors affecting the dynamic range of the SERF atomic spin gyroscope.

[0005] Currently, no effective method for testing optical polarizability has been found in the existing technology. Summary of the Invention

[0006] This invention addresses the shortcomings of existing technologies by proposing a method for detecting the optical polarization effect of a SERF atomic spin gyroscope.

[0007] The above-mentioned objective of this invention is achieved through the following technical solution:

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

[0009] Step 1: Select the experimental apparatus for testing. The experimental apparatus adopts a K-based method. 3 He's atomic spin system consists of the following main components: a pump optical path, a probe optical path, a magnetic shielding cylinder, a three-dimensional compensation coil, an atomic gas cell, and a heating and insulation system. The atomic gas cell is a spherical glass gas cell. The pump optical path includes a seed light source and a TA amplifier to polarize the two atomic gases in the atomic gas cell. The probe optical path includes a linearly polarized light source, a beam splitter after passing through the gas cell, and a dual-path differential optical detector. The three-dimensional compensation coil surrounds the atomic gas cell 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 probe light direction, and the y-direction is the sensitive axis direction.

[0010] Step 2, based on the K- selected in Step 1 3 He's atomic spin system opens the pump optical path and polarizes the two gases in the atomic chamber, thus realizing the transfer of electron angular momentum to nuclear spin angular momentum.

[0011] Step 3: Based on the K- selected in Step 1 3 He's atomic spin system activates the optical detection path to detect optical signals.

[0012] Step 4: Apply a single-pulse perturbation of an alternating magnetic field in the y-direction to cause the K atoms to deflect at a small angle, generating Larmor precession, and maintaining K and 3 The strong coupling effect of He atoms was used to linearly fit the precession frequency of K atoms under different main magnetic fields. The slope value of the linear fit was used to calculate the electron spin polarizability. The intercept value when the applied main magnetic field value is 0 was used to calculate the equivalent magnetic field generated by the nuclear spin. The slope and intercept values ​​were used to detect the direct and indirect polarization effects of pump light on the two types of atoms.

[0013] Furthermore, in step 1, the atomic gas chamber is filled with N2 vapor.

[0014] Furthermore, in step 2, a circularly polarized pump seed light source is used to output a light beam with a diameter of about 5 mm and a wavelength of 770 nm, which is the first resonant wavelength of the K atom. After the light beam passes through a TA amplifier, the optical power is adjusted to more than 200 mW. The amplified light beam is then injected into the atomic gas cell along the z-direction. After a 12-hour polarization process, the transfer of electron angular momentum to nuclear spin angular momentum is achieved.

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

[0016] Furthermore, in step 4, the linear fitting formula for 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 γ = γ of the alkali metal atoms. 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 atom nucleus; the value of Q depends on the polarization state of the ensemble, ranging from Q=6 in ultra-low polarization to Q=4 in saturation polarization; Q is related to the electron spin polarizability P. e The expression is:

[0019]

[0020] Using the slope k in relation to the slowing factor Q and the electronic spin polarization P e Solve the problem;

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

[0022]

[0023] Wherein, κ0 is due to the electron wavefunction of the K atom and 3 The spin exchange enhancement factor generated by the overlap of He atomic nuclei is constant at a fixed temperature; the magnetization density M = μn corresponds to a polarized sample with magnetic moment μ0 and atomic density n; the combined equivalent magnetic field resulting from 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 Let λ be the magnetization density of the K atom, and λ be the intrinsic coefficient of the magnetic moment. and They are respectively 3 Polarizability of He and K atoms;

[0026] The value of the combined equivalent magnetic field is equivalent to... 3 The equivalent magnetic field of He on the K atom is expressed by the intercept b and the gyromagnetic ratio γ of the K atom. e The ratio determines B n Size, 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 this invention are as follows:

[0028] 1. The method for detecting the optical polarization effect of the SERF atomic spin gyroscope designed in this invention utilizes 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. This causes the electron spins of alkali metal gas atoms to deflect slightly away from the upper state of the Bloch sphere, simultaneously exciting Larmor precession. The precession frequency of the corresponding alkali metal gas atoms is measured without disturbing the inert gas atoms. By linearly fitting the frequency values ​​under different longitudinal main magnetic fields, the electron gyromagnetic ratio of the alkali metal gas atoms is calibrated using the fitting slope, thus determining the accurate electron spin polarizability and judging the effect of light on the polarization of alkali metal atoms. The equivalent magnetic field generated by the inert gas atoms is calibrated using the fitting intercept, determining the indirect polarization effect of the alkali metal gas atoms on the inert gas atoms.

[0029] 2. The single-pulse magnetic field perturbation method for measuring electron spin polarization and nuclear spin equivalent magnetic field designed in this invention can achieve intuitive detection of the polarization effect of the pump optical system on the atomic gas cell in a SERF atomic spin gyroscope while maintaining strong coupling between alkali metal gas atoms and inert gas atoms. It presents the effects of direct and indirect polarization of atoms by light using linear numerical fitting. The working principle is clear, the structure is simple, and the testing efficiency is high. It can provide an important evaluation method and reference for the optical parameter effect of SERF atomic spin gyroscopes. Attached Figure Description

[0030] Figure 1 This is a basic schematic diagram of the SERF atomic spin gyroscope; 1a shows the working state of the SERF atomic spin gyroscope when it is stationary, and 1b shows the working state of the SERF atomic spin gyroscope when it is rotating.

[0031] Figure 2 Based on K- 3 A schematic diagram of He's SERF atomic spin gyroscope device;

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

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

[0034] The structure of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that these embodiments are descriptive and not limiting.

[0035] Figure 1This is a basic schematic diagram of the SERF atomic spin gyroscope. Applying an external magnetic field B causes Larmor precession of the atomic spins, with a frequency ω: ω = γ|B|, where the gyromagnetic ratio γ can be used as a conversion factor between frequency and field strength. Atoms are polarized by optical pumping, transferring photon angular momentum from a circularly polarized beam tuned to the atomic resonance frequency to the collection of atoms. A linearly polarized beam propagating in a direction orthogonal to the pump beam is used to detect atomic polarization. When the probe beam passes through alkali metal vapor, its polarization plane rotates along that direction at an angle proportional to the spin component. The SERF atomic spin gyroscope utilizes the strong coupling between the nuclear spin of inert gas atoms and the electron spin of alkali metal atoms under specific conditions. The nuclear spin of the inert gas atoms can automatically track and compensate for changes in the external magnetic field, thus isolating the influence of the external magnetic field B on the electron spin axis of the alkali metal atoms. Ultimately, angular motion measurements can be performed, such as... Figure 1 As shown, when the carrier rotates, the electron spins of the alkali metal atoms remain fixed on their axes. The detection laser is fixed to the carrier and rotates with it. The angle between the laser and the electron spins reflects the carrier's rotation relative to inertial space.

[0036] Based on the basic working principle of the SERF atomic spin gyroscope, this invention proposes a method for detecting the optical polarization effect of the SERF atomic spin gyroscope. The pump light transfers the photon angular momentum to the electron angular momentum of alkali metal gas atoms, achieving macroscopic polarization of the electron spins in the alkali metal atoms. The polarization effect of the alkali metal gas atoms can be evaluated using the electron spin polarizability. Simultaneously, the electron spins of the alkali metal atoms can polarize the nuclear spins of the inert gas, achieving macroscopic polarization of the nuclear spins. During this process, the two types of atoms collide and strongly couple. At the same time, the inert gas atoms generate an equivalent magnetic field on the alkali metal gas atoms. The value of the equivalent magnetic field reflects the magnitude of the nuclear spin polarizability; therefore, the polarization effect of the inert gas atoms can be evaluated using 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 cell, the electron spin polarizability and the magnitude of the equivalent magnetic field can be measured, thereby determining the direct and indirect polarization effect of the pump light system on the atomic gas cell.

[0037] The technical solution adopted in this invention is as follows:

[0038] A method for detecting the optical polarization effect of a SERF atomic spin gyroscope, the invention of which includes the following steps:

[0039] Step 1: Select the experimental apparatus for testing. The experimental apparatus adopts a K-based method. 3He's atomic spin system comprises a pump optical path, a probe optical path, a magnetic shielding cylinder 4, a three-dimensional compensation coil 5, an atomic gas cell 7, and a heating and insulation system 6. The atomic gas cell is a spherical glass cell with a diameter of 1 cm. The pump optical path, used to polarize the atomic gas cell, includes a seed light source 1 and a TA amplifier 2. The probe optical path includes a linearly polarized light source 3, a beam splitter 8 after passing through the gas cell, and a dual-path differential optical detector. The dual-path differential optical detector includes a mirror 9, a photoelectric balance detector 10, and an oscilloscope 11. The three-dimensional compensation coil provides alternating magnetic fields of different frequencies and magnitudes to the atomic gas cell in three dimensions. Applying a small-angle pulsed magnetic field in the y-direction allows for the measurement of electron spin polarization and the equivalent magnetic field generated by nuclear spin, thereby detecting the photopolarization effect.

[0040] In the preparation of the atomic gas cell, any non-uniform region within the cell will generate first-order and higher-order gradients in the magnetic field. Consequently, electron spins will precess at different rates within the decoherent magnetic field gradient. The largest source of non-uniformity in the cell is the pull-off stem during cell fabrication. This effect is mitigated by plugging the pull-off stem with a drop of potassium metal. K vapor is used as the alkali metal atomic gas. 3 He vapor, as an inert gas, has a density much greater than K vapor. On one hand, it can act as a high-pressure inert buffer gas to fill the atomic gas cell, suppressing the diffusion of K vapor and preventing the alkali metal spins from immediately depolarizing after colliding with the glass wall of the gas cell. 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 axis-fixing effect of the electron spin of alkali metal atoms, thus achieving a gyroscopic effect. At the same time, sufficient N2 vapor is filled into the atomic gas chamber to quench the electrons in the excited state in the K atom vapor. Without interfering with the spin orientation, the orbital angular momentum of the K atom is eliminated by exciting the rotational state of N2, causing it to return to the ground state.

[0041] The atomic gas chamber is fixed to the corresponding mounting structure. A schematic diagram of the device is shown below. Figure 2 As shown, a three-dimensional compensation coil surrounds the atomic gas cell, generating an alternating pulsed magnetic field with adjustable frequency and amplitude. The z-direction is the main magnetic field direction, the x-direction is the probe light direction, and the y-direction is the sensitive axis direction. The longitudinal direction z corresponds to the main magnetic field, determining the precession frequency of the atomic spin, which is generally a stable DC value. The transverse direction x corresponds to the probe light direction, and the transverse direction y corresponds to the gyroscope's sensitive axis direction. By applying the frequency and magnitude of a single-pulse magnetic field in the y-direction, the deflection angle of the alkali metal atom's electron spin quantum state can be adjusted. In this invention, spin precession targeting only the alkali metal atom gas is achieved while maintaining the strong coupling effect between the alkali metal gas atoms and the inert gas atoms.

[0042] Step 2, based on the K- selected in Step 13 He's atomic spin system opens the pump optical path and polarizes the two gases in the atomic gas chamber, realizing the transfer of electron 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 with a diameter of about 5 mm and a wavelength of 770 nm, which is the first resonant wavelength of the K atom. After the light beam passes through a TA amplifier, the optical power is adjusted to more than 200 mW, and the power-amplified light beam is injected into the atomic gas cell along the z-direction.

[0044] After a 12-hour polarization process, the pump optical path gradually generates direct and indirect polarization on the two types of atoms using circularly polarized light. This process gradually pumps the electrons of the alkali metal atoms from the ground state 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 atoms and the electron spin of the alkali metal atoms undergo exchange collisions and strong coupling, realizing the transfer of electron angular momentum to nuclear spin angular momentum.

[0045] Step 3: Based on the K- selected in Step 1 3 The atomic spin system of He is used to activate the detection optical path for optical signal detection. In this embodiment of the invention, the diameter of the output spot of the linearly polarized probe light is about 5 mm, and the wavelength is selected to ensure the strongest optical signal while being far from the resonant wavelength of the K atom. The probe light is injected into the atomic gas cell along the x-direction. Due to the Faraday rotation effect generated after the atomic vapor is pumped and polarized, the polarization plane of the linearly polarized probe light rotates after passing through the atomic gas cell. After being split by a 1:1 beam splitter, the light is incident on the photoelectric balanced detector with equal intensity to achieve optical signal detection.

[0046] Step 4: Detect the optical polarization effect.

[0047] By altering the magnitude of the main magnetic field of the three-dimensional compensation coil and applying a single-pulse perturbation of the alternating magnetic field in the y-direction, the atoms are deflected away from the upper state of the Bloch sphere. The deflection angle is controlled by changing the frequency and amplitude of the magnetic field pulse. Since the gyromagnetic ratio of K atoms is much greater than... 3 He atoms, therefore, require a smaller magnetic field value to deflect the quantum state of K atoms. By controlling the frequency and amplitude of the magnetic field pulse in the y direction, the K atoms can be deflected at a small angle, thereby generating precession. The precession frequency of the corresponding main magnetic field can be detected. At this time, the quantum state of He atoms in the bloch sphere remains unchanged, that is, the strong coupling state of the two atoms is maintained.

[0048] Linear fitting was performed on the precession frequencies of K atoms under different main magnetic fields, 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 γ = γ of the alkali metal atoms. 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 atom nucleus. For K atoms, the value of Q depends on the polarization state of the ensemble, ranging from ultra-low polarization (P... e =0) Q=6 to saturation polarization (P = 0) e =1) Q=4. The slowing factor Q and the electronic spin polarizability P e The expression is:

[0051]

[0052] Therefore, the slope k can be used to describe the slowing factor Q and the electronic spin polarization P. e The solution is then performed. Furthermore, the intercept b represents the frequency component when the applied main magnetic field value is 0, at which point the atomic gas cell is only affected by the equivalent magnetic field generated by the coupling between alkali metal atoms and inert gas atoms.

[0053]

[0054] Where κ0 is due to the electron wavefunction of the K atom and 3 The spin exchange enhancement factor resulting from the overlap of He atomic nuclei is constant at a fixed temperature, κ0. The magnetization density M = μn corresponds to a polarized sample with a magnetic moment of μ0 and an atomic density of n. Although... 3 The magnetic moment of He is much smaller than that of K, but because 3 He vapor has a high atomic density n and a magnetization density M. n The magnetization density M of K atoms e Much larger. The combined equivalent magnetic field of their interaction is

[0055]

[0056] The value of the combined equivalent magnetic field is approximately equal to 3 The equivalent magnetic field of He on K atoms, due to 3 He's nuclear spin polarization Due to the influence of various relaxation mechanisms, it cannot be solved directly. Therefore, the intercept b and the gyromagnetic ratio γ of the K atom can be used. e The ratio determines B n Size, thus affecting 3 The polarizability of He is used to determine the K atom pair. 3 Detection of He polarization effect.

[0057] In this embodiment of the invention, after the pump power stabilizes at 200mW and is polarized for 12 hours, a single-pulse perturbation with an alternating magnetic field is applied in the y-direction, and the measurement results are as follows. Figure 3 As shown. The slope value k = 7.0393 Hz / nT represents the gyromagnetic ratio γ = γ of the alkali metal atom. e / Q(γ e =28Hz / nT), calculated to be Q≈4, at which point the electronic spin polarizability P of the alkali metal atom K is... e The value ≈1 proves that the pump at this optical power produces complete polarization of the K atom. The intercept value b = -556.93 Hz corresponds to the K atom experiencing [polarization] in a zero magnetic field environment. 3 The equivalent magnetic field exerted by He atoms on it is B. n = -79.56nT, and by Can be mapped to inert gases 3 Nuclear spin polarization of He atoms The strength of K atoms is used to realize the K atom pair 3 Polarization detection of He atoms.

[0058] To conduct a comparative experiment when the photopolarized atomic interaction is weak, the pump power was stabilized at 20 mW by adjusting the TA and polarized for 12 hours. A single-pulse magnetic field was applied in the y-direction, and measurements were performed as described above. The results are as follows. Figure 3 As shown, Q≈5.3 is obtained, at which point the electronic spin polarizability P of the alkali metal atom K is... e ≈0.46, proving that the pump at this optical power does not produce complete polarization of the K atom, while the corresponding 3 The equivalent magnetic field of He atoms is also relatively small, that of B. n = -16.17nT, proving that the low-power pump pair 3 The indirect polarization effect of He atoms is also relatively weak. In summary, the slope and intercept of the linear fit can be used to reflect the effect of the pump light on K atoms and... 3 The direct and indirect polarization effects of He atoms enabled the measurement of the optical polarization of a SERF atom spin gyroscope using a small-angle single-pulse magnetic field perturbation in the y-direction.

[0059] Although embodiments and drawings of the present invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations 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 optical polarization effect of a SERF atomic spin gyroscope, characterized in that: Includes the following steps: Step 1: Select the experimental apparatus for testing. The experimental apparatus adopts a K-based method. 3 He's atomic spin system consists of the following main components: a pump optical path, a probe optical path, a magnetic shielding cylinder, a three-dimensional compensation coil, an atomic gas cell, and a heating and insulation system. The atomic gas cell is a spherical glass gas cell. The pump optical path includes a seed light source and a TA amplifier to polarize the two atomic gases in the atomic gas cell. The probe optical path includes a linearly polarized light source, a beam splitter after passing through the gas cell, and a dual-path differential optical detector. The three-dimensional compensation coil surrounds the atomic gas cell 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 probe light direction, and the y-direction is the sensitive axis direction. Step 2, based on the K- selected in Step 1 3 He's atomic spin system opens the pump optical path and polarizes the two gases in the atomic gas chamber, realizing the transfer of electron angular momentum to nuclear spin angular momentum. Step 3: Based on the K- selected in Step 1 3 He's atomic spin system activates the optical detection path to detect optical signals; Step 4: Apply a single-pulse perturbation of an alternating magnetic field in the y-direction to cause the K atoms to deflect at a small angle, generating Larmor precession, and maintaining K and 3 The strong coupling effect of He atoms was used to linearly fit the precession frequency of K atoms under different main magnetic fields. The slope value of the linear fit was used to calculate the electron spin polarizability. The intercept value when the applied main magnetic field value is 0 was used to calculate the equivalent magnetic field generated by the nuclear spin. The slope and intercept values ​​were used to detect the direct and indirect polarization effects of pump light on the two types of atoms.

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

3. The method for detecting the optical polarization effect of a 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 light beam with a diameter of about 5 mm and a wavelength of 770 nm, which is the first resonant wavelength of the K atom. After the light beam passes through a TA amplifier, the optical power is adjusted to more than 200 mW. The amplified light beam is then injected into the atomic gas cell 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 optical polarization effect of a SERF atomic spin gyroscope according to claim 1, characterized in that: In step 3, the diameter of the light spot output by the linearly polarized detection light source is 5 mm and the wavelength is 766 nm.

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

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