A method for suppressing angular velocity coupling noise based on pulse polarization

Abstract

A pulsed polarization-based method for suppressing angular velocity coupling noise involves applying pulsed pump light and measuring the electron spin decay oscillation signal after the pump light is turned off. The decoupling phase of the angular velocity measurement is calibrated using the Earth's rotational angular velocity as the standard angular velocity input. The angular velocity input information is then derived from the decay oscillation signal amplitude. This method facilitates angular velocity decoupling measurements of the coupled spin ensemble of alkali metal electron spins and inert gas nuclear spins. The method is rational, simple to perform, and applicable to conditions such as longitudinal optical frequency shifts introduced by the pump light and interactions between coupled spin ensembles. It can suppress angular velocity coupling noise and provides a foundation for the development of high-precision atomic spin inertial measurement devices.

Description

Technical Field

[0001] The present invention relates to the technical field of atomic spin inertial measurement, and in particular to a method for suppressing angular velocity coupling noise based on pulse polarization, which can solve the angular velocity measurement coupling problem and provide a basis for the development of high-precision atomic spin inertial measurement devices. Background Art

[0002] Suppressing angular velocity coupling noise is essential for achieving high-precision atomic spin inertial measurement. Based on an experimental configuration consisting of a single pump beam and a single detection beam, an atomic spin inertial measurement device operating at the nuclear spin self-compensation point is theoretically only sensitive to angular velocity inputs perpendicular to both the pump and detection beams. However, due to factors such as the longitudinal optical frequency shift of the pump beam, the device is also sensitive to angular velocity inputs in the detection direction, generating angular velocity coupling noise.

[0003] Currently, methods such as K-Rb optical frequency shift cancellation, magnetic field compensation, and two-beam laser cancellation are used to eliminate the optical frequency shift introduced by the pump light. However, the cancellation accuracy is dependent on the evaluation criteria, and the cancellation schemes are difficult to implement. Furthermore, magnetic field modulation is used to suppress coupling noise. However, operating at a specific decoupling point affects the self-compensation performance of the inertial measurement unit. Furthermore, magnetic field manipulation can cause relaxation of the coupled atomic ensemble, affecting the angular velocity measurement scale factor. Currently, coupling noise suppression is limited and may result in reduced sensitivity and limited self-compensation performance. Summary of the Invention

[0004] In view of the defects or deficiencies in the prior art, the present invention provides an angular velocity coupling noise suppression method based on pulse polarization, which can solve the angular velocity measurement coupling problem and provide a basis for the development of high-precision atomic spin inertial measurement devices.

[0005] The technical solutions of the present invention are as follows:

[0006] A method for suppressing angular velocity coupling noise based on pulse polarization, characterized by comprising the following steps:

[0007] Step 1: Design a pulse polarization control cycle based on the electron spin precession frequency for an atomic spin inertial measurement device;

[0008] Step 2: The polarization axis, i.e., the z-axis, of the atomic spin inertial measurement device is perpendicular to the horizontal plane of the laboratory. The direction of the detection light, i.e., the x-axis, is initially oriented north, and the y-axis is perpendicular to both the detection light and the polarized light. The x-axis and y-axis of the atomic spin inertial measurement device are rotated 15° around an axis perpendicular to the ground using a single-axis turntable.

[0009] Step 3: Collect the electron spin decay oscillation signal after the pump light is turned off for 30 seconds;

[0010] Step 4: Determine whether the rotation has reached 360°. If not, return to step 2. If yes, proceed to step 5.

[0011] Step 5, extracting the decay oscillation data of the precession frequency stable stage;

[0012] Step 6: Adjust the coefficient of the decay oscillation term of the fitting phase analysis to obtain the sin term fitting coefficient and the cos term fitting coefficient;

[0013] Step 7: Determine whether the angular velocity is decoupled, that is, the sin fitting coefficient is only related to the x-axis angular velocity Ω x The cosine term fitting coefficient is only related to the y-axis angular velocity Ω y If not, go back to step 6, if yes, go to step 8;

[0014] Step 8: calibrate the angular velocity measurement decoupling phase, and obtain angular velocity input information from the amplitude of the decaying oscillation signal to perform angular velocity measurement.

[0015] Step 1 includes designing the pulse control cycle to measure the complete electron spin decay oscillation signal in the detection phase when the pump light is turned off. 1250s -1 When the electron spin resonance frequency f is 200 Hz, it is necessary to measure at least 5 cycles of the decaying oscillation signal, that is, 25 ms, to ensure that the measured signal contains the signal in the stable frequency stage of the oscillation.

[0016] The loop process from step 2 to step 4 includes taking both the x-axis and the y-axis as the transverse sensitive axis, rotating the transverse sensitive axis once in order to utilize the projection of the earth's rotation angular velocity on the ground where the parallel device is located as Ω x Input signal and Ω y The input signal is in the form of cosine Ω during one rotation. x and Ω in sin form y Perform pulse polarization angular velocity measurement signal calibration.

[0017] The precession frequency stabilization stage in step 5 is the stage where the electron longitudinal polarization rate decreases to below 0.1. At this time, the corresponding precession frequency changes relatively slowly, and the alkali metal electron spin evolution process is approximately a linear evolution process. According to the analysis of the dynamic evolution process of the coupled spin ensemble during the pulse polarization process, the theoretical expression of the measured signal in this stage is:

[0018]

[0019] in, is the electron spin polarization in the direction detected by atomic spin inertial measurement, is the electron spin transverse relaxation rate in the stable stage of decay oscillation, is the longitudinal relaxation rate of the electron spin in the stable stage of decay oscillation, i.e., the z-axis direction, t is the time of decay oscillation signal, Q is the slowing factor, k is the scale factor of the system's response to angular velocity, Ω x is the x-axis angular velocity input, Ω y is the y-axis angular velocity input, γ e is the electron spin gyromagnetic ratio, B z is the applied z-axis bias magnetic field, is the z-axis nuclear spin equivalent magnetic field, is the angular velocity measurement decoupling phase, is the electron spin steady-state polarizability when the pump light is turned on, k d is the longitudinal attenuation coefficient, and C is the constant term.

[0020] Step 6 includes the following fitting formula:

[0021]

[0022] in, is the electron spin polarization in the direction detected by atomic spin inertial measurement, is the electron spin transverse relaxation rate in the stable stage of decay oscillation, t is the time of decay oscillation signal, Q is the slowing factor, is the electron spin longitudinal relaxation rate in the stable stage of decay oscillation, i.e., the z-axis direction, f is the electron spin decay oscillation frequency in the stable stage of decay oscillation, A and B are the fitting coefficients of the sin term and cos term in the decay oscillation signal, respectively. is the fitting phase, D is the longitudinal attenuation coefficient, and C is the constant term.

[0023] The technical effects of the present invention are as follows: A pulsed polarization-based angular velocity coupling noise suppression method is provided. By applying pulsed pump light and measuring the electron decay oscillation signal after the pump light is turned off, the angular velocity measurement decoupling phase is calibrated using the Earth's rotational angular velocity as a standard angular velocity input. The angular velocity input information is obtained from the decay oscillation signal amplitude, facilitating angular velocity decoupling measurement of the alkali metal electron spin-inert gas nuclear spin coupled spin ensemble. The method is rational, simple to perform, and applicable to conditions such as longitudinal optical frequency shift introduced by the pump light and interaction between coupled spin ensembles. It can suppress angular velocity coupling noise and provides a foundation for the development of high-precision atomic spin inertial measurement devices.

[0024] The advantages of the present invention over the prior art are: (1) The present invention utilizes pulsed polarization to achieve angular velocity coupling noise suppression. Compared to the prior art, the angular velocity coupling noise suppression effect is not dependent on the accuracy of eliminating the longitudinal optical frequency shift. At the same time, the atomic spin inertial measurement remains in a nuclear spin self-compensation state, ensuring the active magnetic compensation capability of the atomic spin inertial measurement. (2) The present invention is rational and the experimental operation is simple, providing a foundation for the development of high-precision atomic spin inertial measurement devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a flow chart of implementing a method for suppressing angular velocity coupling noise based on pulse polarization according to the present invention. Figure 1 The method includes step 1, designing the pulse control period; step 2, rotating the device 15° around the rotation axis; step 3, collecting the attenuated oscillation signal after turning off the pump light for 30 seconds; step 4, judging whether the rotation has reached 360°, if not, returning to step 2, if yes, entering step 5; step 5, extracting the attenuated oscillation term data in the precession frequency stabilization stage; step 6, adjusting the fitting phase to analyze the attenuated oscillation term coefficient; step 7, judging whether the angular velocity is decoupled, if not, returning to step 6, if yes, entering step 8; step 8, obtaining the angular velocity measurement result. DETAILED DESCRIPTION

[0026] Below is the attached figure ( Figure 1 ) and Examples illustrate the present invention.

[0027] Figure 1 This is a flow chart of a method for suppressing angular velocity coupling noise based on pulse polarization according to the present invention. Figure 1 As shown, a method for suppressing angular velocity coupling noise based on pulse polarization includes the following steps: step 1, designing a pulse polarization manipulation cycle for an atomic spin inertial measurement device based on the electron spin precession frequency; step 2, making the polarization axis, i.e., the z-axis, in the atomic spin inertial measurement device perpendicular to the horizontal plane of the laboratory, the detection light direction, i.e., the x-axis direction, the initial direction of the x-axis points to the north, and the y-axis direction is perpendicular to both the detection light and the polarized light (the y-axis is the sensitive axis in the continuous polarization mode, and both the x-axis and the y-axis are sensitive axes in the pulse polarization mode), and using a single-axis turntable to make the atomic spin inertial measurement device perpendicular to the horizontal plane of the laboratory The x-axis and y-axis in the spin inertial measurement device rotate 15° around the axis of rotation perpendicular to the ground; Step 3, collect the electron spin decay oscillation signal after turning off the pump light for 30 seconds; Step 4, determine whether the rotation has reached 360°, if not, return to Step 2, if yes, go to Step 5; Step 5, extract the decay oscillation term data in the precession frequency stabilization stage; Step 6, adjust the fitting phase to analyze the decay oscillation term coefficient, and obtain the sin term fitting coefficient and cos term fitting coefficient; Step 7, determine whether the angular velocity is decoupled, that is, the sin term fitting coefficient is only related to the x-axis angular velocity Ω xThe cosine term fitting coefficient is only related to the y-axis angular velocity Ω y If no, return to step 6, if yes, go to step 8; Step 8, calibrate the angular velocity measurement decoupling phase, and obtain angular velocity input information from the attenuated oscillation signal amplitude to perform angular velocity measurement.

[0028] Step 1 includes designing the pulse control cycle to measure the complete electron spin decay oscillation signal in the detection phase when the pump light is turned off. 1250s -1 When the electron spin resonance frequency f is 200 Hz, it is necessary to measure at least 5 cycles of the decaying oscillation signal, i.e., 25 ms, to ensure that the measured signal contains the signal of the oscillation stable frequency phase. The loop process from step 2 to step 4 includes using both the x-axis and the y-axis as the transverse sensitive axis. The transverse sensitive axis is rotated once in order to use the projection of the earth's rotational angular velocity on the ground where the parallel device is located as Ω. x Input signal and Ω y The input signal is in the form of cosine Ω during one rotation. x and Ω in sin form y Perform pulse polarization angular velocity measurement signal calibration.

[0029] The precession frequency stabilization stage in step 5 is the stage where the electron longitudinal polarization rate decreases to below 0.1. At this time, the corresponding precession frequency changes relatively slowly, and the alkali metal electron spin evolution process is approximately a linear evolution process. According to the analysis of the dynamic evolution process of the coupled spin ensemble during the pulse polarization process, the theoretical expression of the measured signal in this stage is:

[0030]

[0031] in, is the electron spin polarization in the direction detected by atomic spin inertial measurement, is the electron spin transverse relaxation rate in the stable stage of decay oscillation, is the longitudinal relaxation rate of the electron spin in the stable stage of decay oscillation, i.e., the z-axis direction, t is the time of decay oscillation signal, Q is the slowing factor, k is the scale factor of the system's response to angular velocity, Ω x is the x-axis angular velocity input, Ω y is the y-axis angular velocity input, γ e is the electron spin gyromagnetic ratio, B z is the applied z-axis bias magnetic field, is the z-axis nuclear spin equivalent magnetic field, is the angular velocity measurement decoupling phase, is the electron spin steady-state polarizability when the pump light is turned on, k dis the longitudinal attenuation coefficient, and C is the constant term.

[0032] Step 6 includes the following fitting formula:

[0033]

[0034] in, is the electron spin polarization in the direction detected by atomic spin inertial measurement, is the electron spin transverse relaxation rate in the stable stage of decay oscillation, t is the time of decay oscillation signal, Q is the slowing factor, is the electron spin longitudinal relaxation rate in the stable stage of decay oscillation, i.e., the z-axis direction, f is the electron spin decay oscillation frequency in the stable stage of decay oscillation, A and B are the fitting coefficients of the sin term and cos term in the decay oscillation signal, respectively. is the fitting phase, D is the longitudinal attenuation coefficient, and C is the constant term.

[0035] The present invention relates to the field of atomic spin inertial measurement devices, and in particular to a method for suppressing angular velocity coupling noise based on pulse polarization. The angular velocity coupling noise suppression method is reasonable, simple to operate, can solve the angular velocity measurement coupling problem, and provides a basis for the development of high-precision atomic spin inertial measurement devices.

[0036] A method for suppressing angular velocity coupling noise based on pulse polarization, characterized by comprising the following steps:

[0037] Step (1): Design the pulse polarization control period based on the electron spin precession frequency.

[0038] Step (2): Make the polarization axis z of the atomic spin inertial measurement device perpendicular to the horizontal plane of the laboratory, detect the initial direction of the x-axis pointing to the north, use a single-axis turntable to rotate the device's transverse sensitive axes x and y 360° around the axis perpendicular to the ground, and measure and collect data every 15°.

[0039] Step (3): Measure the decaying oscillation signal after turning off the pump light for 30 seconds at each angle.

[0040] Step (4): Extract the decay oscillation data during the stable phase of the precession frequency.

[0041] Step (5): Use the formula to fit the amplitude of the oscillation term and adjust the fitting phase until the sin term is only equal to the angular velocity Ω of the detection light, i.e. the x-axis. x The cosine fitting coefficients are only related to the angular velocity Ω in the direction perpendicular to the detection and pumping directions, i.e., the y-axis. y Related.

[0042] Step (6): Angular velocity measurement is performed based on the set fitting phase.

[0043] The design of the pulse polarization control cycle based on the electron spin precession frequency in step (1) refers to designing the pulse control cycle to achieve the complete electron spin decay oscillation signal measured in the detection stage. About 1250s -1 When the electron spin resonance frequency f is about 200 Hz, it is necessary to measure at least 5 cycles of the decaying oscillation signal, that is, 25 ms, to ensure that the measured signal contains the signal in the stable frequency stage of the oscillation.

[0044] In step (2), the polarization axis is the propagation direction of the pumping light, and the transverse sensitive axis is the propagation direction of the detection light and the direction perpendicular to both the pumping light and the detection light; rotating the sensitive axis of the device once is intended to use the projection of the earth's rotation angular velocity on the ground parallel to the device as the angular velocity Ω of the x-axis. x and the angular velocity of the y-axis Ω y Input signal, if the initial detection direction is the x-axis pointing to the north, measure the angular velocity of the x-axis Ω during the turntable's rotation. x In cosine form, the angular velocity of the y-axis Ω y It is in the form of sin, which is used to calibrate the pulse polarization angular velocity measurement signal.

[0045] The precession frequency stabilization stage in step (4) is the stage where the electron longitudinal polarization rate drops below 0.1. At this time, the corresponding precession frequency changes relatively slowly, and the alkali metal electron spin evolution process can be approximated as a linear evolution process. Based on the analysis of the dynamic evolution process of the coupled spin ensemble during the pulse polarization process, the theoretical expression of the measured signal in this stage is:

[0046]

[0047] in, is the electron spin polarization in the direction detected by atomic spin inertial measurement, is the electron spin transverse (x and y directions) relaxation rate in the stable stage of decay oscillation, is the longitudinal (z-direction) relaxation rate of the electron spin in the stable stage of decay oscillation, t is the time of decay oscillation signal, Q is the slowing factor, k is the scale factor of the system response to angular velocity, and the scale factor is related to system parameters such as the pumping rate, longitudinal optical frequency shift, and pulse duty cycle in the stage of pump light on. x is the angular velocity input of the detection light, i.e. the x-axis, Ω y is the angular velocity input in the direction perpendicular to the detection and pumping direction, i.e., the y-axis, γ e is the electron spin gyromagnetic ratio, B z is the applied z-axis bias magnetic field, is the z-axis nuclear spin equivalent magnetic field, is the angular velocity measurement decoupling phase, is the electron spin steady-state polarizability when the pump light is turned on, k d is the longitudinal attenuation coefficient, which is related to the input quantity and the nuclear spin equivalent magnetic field, and C is a constant term.

[0048] The fitting formula in step (5) is as follows:

[0049]

[0050] in, is the electron spin polarization in the direction detected by atomic spin inertial measurement, is the electron spin transverse relaxation rate in the stable stage of decay oscillation, t is the time of decay oscillation signal, Q is the slowing factor, is the electron spin longitudinal relaxation rate in the stable stage of decay oscillation, i.e., the z-axis direction, f is the electron spin decay oscillation frequency in the stable stage of decay oscillation, A and B are the fitting coefficients of the sin term and cos term in the decay oscillation signal, respectively. is the fitting phase, D is the longitudinal attenuation coefficient, and C is the constant term.

[0051] Any content not described in detail in this specification is prior art known to those skilled in the art. It should be noted that the above description is intended to help those skilled in the art understand the present invention, but does not limit the scope of protection of the present invention. Any equivalent substitution, modification, improvement, and / or simplification of the above description that does not depart from the essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for suppressing angular velocity coupling noise based on pulse polarization, characterized in that: The following steps are involved: Step 1: Design a pulse polarization control cycle based on the electron spin precession frequency for an atomic spin inertial measurement device; Step 2: The polarization axis, i.e., the z-axis, of the atomic spin inertial measurement device is perpendicular to the horizontal plane of the laboratory. The direction of the detection light, i.e., the x-axis, is initially oriented north, and the y-axis is perpendicular to both the detection light and the polarized light. The x-axis and y-axis of the atomic spin inertial measurement device are rotated 15° around an axis perpendicular to the ground using a single-axis turntable. Step 3: Collect the electron spin decay oscillation signal after the pump light is turned off for 30 seconds; Step 4: Determine whether the rotation has reached 360°. If not, return to step 2. If yes, proceed to step 5. Step 5, extracting the decay oscillation data of the precession frequency stable stage; Step 6: Adjust the coefficient of the decay oscillation term of the fitting phase analysis to obtain the sin term fitting coefficient and the cos term fitting coefficient; Step 7: Determine whether the angular velocity is decoupled, that is, the sin fitting coefficient is only related to the x-axis angular velocity Ω x The cosine term fitting coefficient is only related to the y-axis angular velocity Ω y If not, go back to step 6, if yes, go to step 8; Step 8: calibrate the angular velocity measurement decoupling phase, and obtain angular velocity input information from the amplitude of the decaying oscillation signal to perform angular velocity measurement; Step 6 includes the following fitting formula: in, is the electron spin polarization in the direction detected by atomic spin inertial measurement, is the electron spin transverse relaxation rate in the stable stage of decay oscillation, t is the time of decay oscillation signal, Q is the slowing factor, is the electron spin longitudinal relaxation rate in the stable stage of decay oscillation, i.e., the z-axis direction, f is the electron spin decay oscillation frequency in the stable stage of decay oscillation, A and B are the fitting coefficients of the sin term and cos term in the decay oscillation signal, respectively. is the fitting phase, D is the longitudinal attenuation coefficient, and C is the constant term.

2. The angular velocity coupling noise suppression method based on pulse polarization according to claim 1, characterized in that: Step 1 includes designing the pulse control cycle to measure the complete electron spin decay oscillation signal in the detection phase when the pump light is turned off. 1250s -1 When the electron spin resonance frequency f is 200 Hz, it is necessary to measure at least 5 cycles of the decaying oscillation signal, that is, 25 ms, to ensure that the measured signal contains the signal in the stable frequency stage of the oscillation.

3. The method for suppressing angular velocity coupling noise based on pulse polarization according to claim 1, characterized in that: The loop process from step 2 to step 4 includes taking both the x-axis and the y-axis as the transverse sensitive axis, rotating the transverse sensitive axis once in order to utilize the projection of the earth's rotation angular velocity on the ground where the parallel device is located as Ω x Input signal and Ω y The input signal is in the form of cosine Ω during one rotation. x and Ω in sin form y Perform pulse polarization angular velocity measurement signal calibration.

4. The method for suppressing angular velocity coupling noise based on pulse polarization according to claim 1, characterized in that: The precession frequency stabilization stage in step 5 is the stage where the electron longitudinal polarization rate decreases to below 0.

1. At this time, the corresponding precession frequency changes relatively slowly, and the alkali metal electron spin evolution process is approximately a linear evolution process. According to the analysis of the dynamic evolution process of the coupled spin ensemble during the pulse polarization process, the theoretical expression of the measured signal in this stage is: in, is the electron spin polarization in the direction detected by atomic spin inertial measurement, is the electron spin transverse relaxation rate in the stable stage of decay oscillation, is the longitudinal relaxation rate of the electron spin in the stable stage of decay oscillation, i.e., the z-axis direction, t is the time of decay oscillation signal, Q is the slowing factor, k is the scale factor of the system's response to angular velocity, Ω x is the x-axis angular velocity input, Ω y is the y-axis angular velocity input, γ e is the electron spin gyromagnetic ratio, B z is the applied z-axis bias magnetic field, is the z-axis nuclear spin equivalent magnetic field, is the angular velocity measurement decoupling phase, is the electron spin steady-state polarizability when the pump light is turned on, k d is the longitudinal attenuation coefficient, and C is the constant term.

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