SERF inertial measurement device based on optical cavity detection

Abstract

According to the SERF inertial measurement device based on optical cavity detection, an optical cavity is integrated in an alkali metal gas chamber, so that the effective operating distance of detection laser and atoms in a small volume is increased, the intensity of a system output signal is enhanced, the signal-to-noise ratio of an SERF inertial measurement device signal is improved, and the SERF inertial measurement device has important significance in improving the sensitivity of the SERF inertial measurement device; the device is characterized in that the device comprises an alkali metal gas chamber, a multi-pass reflection light cavity structure is arranged in the alkali metal gas chamber, and the multi-pass reflection light cavity structure comprises a first light cavity reflector located on the incident side of detection light and a second light cavity reflector located on the emergent side of the detection light; the detection light input interface of the first light cavity reflector guides detection light from the outside of the alkali metal gas chamber to the reflecting surface of the second light cavity reflector, and the detection light is reflected back and forth on the two reflecting surfaces to form multi-pass reflection and then is emitted out of the alkali metal gas chamber from the detection light output interface of the second light cavity reflector.

Description

Technical Field

[0001] The present invention relates to the technical field of atomic spin inertial measurement, and in particular to a SERF inertial measurement device based on optical cavity detection. By integrating an optical cavity in an alkali metal gas chamber, the effective action distance between a detection laser and an atom in a small volume is increased, the system output signal strength is enhanced, and the signal-to-noise ratio of a SERF inertial measurement device signal is improved, which is of great significance for improving the sensitivity of the SERF inertial measurement device. Background Art

[0002] The atomic spin inertial measurement device based on the spin-exchange-relaxation-free (SERF) effect amplifies the signal through the interaction between alkali metal atoms and inert gas atoms to achieve SERF inertial measurement. It is one of the development directions of the next generation of ultra-high precision inertial measurement technology and is aimed at new physics research beyond the standard model. Its sensitivity fundamentally determines the limit drift of inertial devices and the detection limit of the system.

[0003] The sensitivity of the SERF inertial measurement device is determined by the signal-to-noise ratio of the detection signal. As a light detection system, the SERF inertial measurement device increases the distance between light and atoms to increase the detection signal strength, which is one of the key technologies to improve the system signal-to-noise ratio. Without changing other system parameters, increasing the optical path of the detection light in the alkali metal chamber can effectively increase the intensity of the system output optical rotation signal and increase the detection sensitivity of the SERF inertial measurement device.

[0004] At present, there is a method to increase the optical path of the detection light by placing external reflectors next to the alkali metal gas chamber. However, since the reflectors are placed on both sides of the alkali metal gas chamber, the detection light will pass through the gas chamber multiple times during the reflection process, which will result in the actual effective action distance of the detection light with the atoms not being significantly improved during the multiple reflections. In addition, the birefringence caused by the gas chamber glass will affect the polarization of the detection light, reducing the accuracy of the system detection signal. In addition, the current method of realizing multi-path reflection of the detection light in the SERF inertial measurement device is to add two plane reflectors in the detection light path. This method cannot achieve a large number of reflections in the small volume of the alkali metal gas chamber, and has limited ability to improve the sensitivity of the SERF inertial measurement device. Summary of the invention

[0005] The problem solved by the present invention is: multiple reflections of detection light in a small volume are realized by integrating an optical cavity in an alkali metal gas chamber, thereby increasing the effective action distance between the detection light and atoms in the alkali metal gas chamber, increasing the signal-to-noise ratio of a SERF inertial measurement device signal, and building a SERF inertial measurement device based on optical cavity detection.

[0006] The technical solution of the present invention is as follows:

[0007] A SERF inertial measurement device based on optical cavity detection includes an alkali metal gas chamber, characterized in that a multi-pass reflection optical cavity structure is arranged inside the alkali metal gas chamber, the multi-pass reflection optical cavity structure includes a first optical cavity reflector located at the incident side of the detection light and a second optical cavity reflector located at the exit side of the detection light, the detection light input interface of the first optical cavity reflector guides the detection light from outside the alkali metal gas chamber to the reflection surface of the second optical cavity reflector, the detection light is reflected back and forth on the two reflection surfaces to form multi-pass reflection, and then is emitted from the detection light output interface of the second optical cavity reflector outside the alkali metal gas chamber.

[0008] The optical cavity reflector is a spherical mirror, a cylindrical mirror or a plane mirror, the side of the optical cavity reflector has a positioning plane, and the detection light input interface and the detection light output interface are both light holes.

[0009] The multi-pass reflection optical cavity structure comprises a silicon wafer bottom surface bonded to an alkali metal gas chamber bottom surface by anodic bonding, and the first optical cavity reflector and the second optical cavity reflector are both fixed to the silicon wafer bottom surface by anodic bonding.

[0010] The alkali metal gas chamber is located in the non-magnetic heating module, the non-magnetic heating module is located in the three-axis compensation coil, the three-axis compensation coil is located in the zinc-manganese ferrite, and the zinc-manganese ferrite is located in the Permalloy magnetic shielding barrel.

[0011] The detection light incident side of the alkali metal gas chamber is connected to the detection laser through the third reflector, the second reflector, the second 1 / 4 wave plate, the photoelastic modulator, the detection polarizer, the second aperture, the third lens, the second lens and the fourth Glan Taylor prism in sequence, and the detection light emitting side of the alkali metal gas chamber is connected to the host computer through the fourth reflector, the fifth reflector, the fourth lens, the detection polarizer, the second photodetector and the phase-locked amplifier module in sequence.

[0012] The signal received by the host computer is:

[0013]

[0014] Among them, S is the output signal of the system, K 1 is the magnification of the optical rotation signal by the system, θ is the optical rotation angle, n is the atomic number density in the gas chamber, c is the speed of light, r e is the electron radius, f D1 is a constant that characterizes the oscillator strength, l is the effective interaction length between the detection light and the atom, v is the detection laser frequency, and v 0 is the center frequency of the absorbed laser, Γ is the pressure broadening of the D1 line of the alkali metal atom, is the longitudinal polarizability of the electron, is the transverse relaxation rate of electrons, γe is the electron gyromagnetic ratio, L z is the optical frequency shift, γ n is the gyromagnetic ratio of the nucleus, Ω y Enter the angular velocity for the system.

[0015] The pumping light incident side of the alkali metal gas chamber is connected to the pumping laser through the first reflector, the first 1 / 4 wave plate, the first aperture, the third Glan Taylor prism, the second 1 / 2 wave plate, the second Glan Taylor prism, the liquid crystal phase retarder, the first Glan Taylor prism, the first 1 / 2 wave plate and the first lens in sequence, and the liquid crystal phase retarder is connected to the third Glan Taylor prism through the optical power stabilization module and the first photodetector in sequence.

[0016] The technical effects of the present invention are as follows: a SERF inertial measurement device based on optical cavity detection of the present invention improves the effective action distance between the detection laser and the atom in a small volume by integrating an optical cavity in an alkali metal gas chamber, enhances the intensity of the system output signal, and improves the signal-to-noise ratio of the SERF inertial measurement device signal, which is of great significance for improving the sensitivity of the SERF inertial measurement device.

[0017] The advantages of the present invention compared with the prior art are:

[0018] (1) The multi-pass reflection optical cavity is integrated into the alkali metal gas chamber so that the propagation path of the detection light is all inside the gas chamber, which reduces the influence of the detection light passing through the gas chamber on the polarization of the detection light and increases the actual effective action distance between the detection light and the atom.

[0019] (2) By designing the parameters of the optical cavity integrated in the alkali metal gas chamber, it is possible to achieve more reflection times within the small volume of the gas chamber, thereby improving the sensitivity limit that the system can achieve and having important significance for the integration and miniaturization of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The structure diagram of a SERF inertial measurement device based on optical cavity detection is implemented in the present invention. SERF is spin-exchange relaxation-free.

[0021] Figure 2 yes Figure 1 Schematic diagram of the alkali metal gas cell structure with an optical cavity.

[0022] Figure 3 yes Figure 1 Schematic diagram of the structure of the optical cavity reflector in the alkali metal gas chamber.

[0023] The reference numerals are as follows: A1-pumping laser; A2-first lens; A3-first 1 / 2 wave plate; A4-first Glan Taylor prism; A5-liquid crystal phase retarder; A6-second Glan Taylor prism; A7-second 1 / 2 wave plate; A8-third Glan Taylor prism; A9-first aperture; A10-first 1 / 4 wave plate; A11-first reflector; A12-first photodetector; A13-optical power stabilization module; B1-detection laser; B2-fourth Glan Taylor prism; B3-second lens; B4-third lens; B5-second aperture; B6-detection polarizer; B7-photoelastic modulator; B8-second 1 / 4 wave plate; B9-second reflector; B10-third reflector; B11-first cavity reflector; B12-second cavity reflector; B13-alkali metal gas chamber; B14-fourth reflector; B15-fifth reflector; B16-fourth lens; B17-detection analyzer; B18-second photodetector; B19-phase-locked amplifier module; B20-host computer; B21-bottom of silicon wafer; B22-gas chamber glass; B23-light hole; B24-positioning plane; B25-high reflective dielectric film; C1-non-magnetic heating module; C2-three-axis compensation coil; C3-vacuum chamber; C4-zinc-manganese ferrite; C5-Permalloy magnetic shielding barrel. DETAILED DESCRIPTION

[0024] Below is the attached figure ( Figure 1-Figure 3 ) and Examples illustrate the present invention.

[0025] Figure 1 It is a structural schematic diagram of a SERF inertial measurement device based on optical cavity detection according to the present invention. Figure 2 yes Figure 1 Schematic diagram of the alkali metal gas cell structure with an optical cavity. Figure 3 yes Figure 1 Schematic diagram of the structure of the optical cavity reflector in the alkali metal gas chamber. Figures 1 to 3 As shown, a SERF inertial measurement device based on optical cavity detection includes an alkali metal gas chamber B13, in which a multi-pass reflection optical cavity structure is arranged, and the multi-pass reflection optical cavity structure includes a first optical cavity reflector B11 located at the incident side of the detection light and a second optical cavity reflector B12 located at the emitting side of the detection light, the detection light input interface of the first optical cavity reflector B11 guides the detection light from outside the alkali metal gas chamber B13 to the reflection surface of the second optical cavity reflector B12, and the detection light is reflected back and forth on the two reflection surfaces to form multi-pass reflection, and then emitted from the detection light output interface of the second optical cavity reflector B12 to the outside of the alkali metal gas chamber B13.

[0026] The optical cavity reflector is a spherical mirror, a cylindrical mirror or a plane mirror, the side of the optical cavity reflector has a positioning plane B24, the detection light input interface and the detection light output interface are both light holes B23, and the optical cavity reflector adopts a high-reflection dielectric film B25 for reflection. The multi-pass reflection optical cavity structure includes a silicon wafer bottom surface B21 bonded to the bottom surface of the alkali metal gas chamber B13 by an anodic bonding method, and the first optical cavity reflector B11 and the second optical cavity reflector B12 are both fixed on the silicon wafer bottom surface B21 by an anodic bonding method.

[0027] The alkali metal gas chamber B13 is located in the non-magnetic heating module C1, the non-magnetic heating module C1 is located in the three-axis compensation coil C2, the three-axis compensation coil C2 is located in the zinc-manganese ferrite C4, and the zinc-manganese ferrite C4 is located in the permalloy magnetic shielding barrel C5. The detection light incident side of the alkali metal gas chamber B13 is connected to the detection laser B1 through the third reflector B10, the second reflector B9, the second 1 / 4 wave plate B8, the photoelastic modulator B7, the detection polarizer B6, the second aperture B5, the third lens B4, the second lens B3 and the fourth Glan Taylor prism B2 in sequence, and the detection light exit side of the alkali metal gas chamber B13 is connected to the host computer B20 through the fourth reflector B14, the fifth reflector B15, the fourth lens B16, the detection polarizer B17, the second photodetector B18 and the phase-locked amplifier module B19 in sequence.

[0028] The signal received by the host computer B20 is:

[0029]

[0030] Among them, S is the output signal of the system, K 1 is the magnification of the optical rotation signal by the system, θ is the optical rotation angle, n is the atomic number density in the gas chamber, c is the speed of light, r e is the electron radius, f D1 is a constant that characterizes the oscillator strength, l is the effective interaction length between the detection light and the atom, ν is the detection laser frequency, and ν 0 is the center frequency of the absorbed laser, Γ is the pressure broadening of the D1 line of the alkali metal atom, is the longitudinal polarizability of the electron, is the transverse relaxation rate of electrons, γ e is the electron gyromagnetic ratio, L z is the optical frequency shift, γ n is the gyromagnetic ratio of the nucleus, Ω y Enter the angular velocity for the system.

[0031] The pumping light incident side of the alkali metal gas chamber B13 is connected to the pumping laser A1 through the first reflector A11, the first 1 / 4 wave plate A10, the first aperture A9, the third Glan Taylor prism A8, the second 1 / 2 wave plate A7, the second Glan Taylor prism A6, the liquid crystal phase retarder A5, the first Glan Taylor prism A4, the first 1 / 2 wave plate A3 and the first lens A2 in sequence, and the liquid crystal phase retarder A5 is connected to the third Glan Taylor prism A8 through the optical power stabilization module A13 and the first photodetector A12 in sequence.

[0032] refer to Figure 1 , Figure 2 , Figure 3 As shown, a SERF inertial measurement device based on optical cavity detection includes an alkali metal gas chamber B13, wherein the alkali metal gas chamber B13 has a multi-pass reflection optical cavity, a detection light incident side and a detection light exit side, wherein the detection light incident side is connected to a third reflector B10, and the detection light exit side is connected to a fourth reflector B14, and the multi-pass optical cavity receives the incident detection light, reflects it multiple times inside the alkali metal gas chamber B13, and then emits it and passes through the detection light exit side to reach the fourth reflector B14.

[0033] The multi-pass reflection optical cavity is bonded inside the alkali metal gas chamber, and includes a first optical cavity reflection mirror B11 and a second optical cavity reflection mirror B12. The first optical cavity reflection mirror B11 and the second optical cavity reflection mirror B12 can be spherical mirrors, cylindrical mirrors or plane mirrors. The detection light is emitted after being reflected multiple times between the first optical cavity reflection mirror B11 and the second optical cavity reflection mirror B12.

[0034] The third reflector B10 is connected to the detection laser B1 through the second reflector B9, the second 1 / 4 wave plate B8, the photoelastic modulator B7, the detection polarizer B6, the second aperture B5, the third lens B4, the second lens B3, and the fourth Glan Taylor prism B2 in sequence. The fourth reflector B14 is connected to the input end of the phase-locked amplifier module B19 through the fifth reflector B15, the fourth lens B16, the detection polarizer B17, and the second photodetector B18 in sequence. The output end of the phase-locked amplifier module B19 is connected to the host computer B20. The heating magnetic shielding system of the alkali metal gas chamber B13 includes a magnetic heating module C1, a three-axis compensation coil C2, a vacuum chamber C3, a zinc-manganese ferrite C4, and a permalloy magnetic shielding barrel C5 in sequence.

[0035] The signal received by the host computer is:

[0036]

[0037] Among them, S is the output signal of the system, K 1 is the amplification factor of the optical rotation signal of the system, n is the atomic number density in the gas chamber, c is the speed of light, r eis the electron radius, f D1 is a constant that characterizes the oscillator strength, l is the effective interaction length between the detection light and the atom, v is the detection laser frequency, and v 0 is the center frequency of the absorbed laser, Γ is the pressure broadening of the D1 line of the alkali metal atom, is the longitudinal polarizability of the electron, is the transverse relaxation rate of electrons, γ e is the electron gyromagnetic ratio, L z is the optical frequency shift, γ n is the gyromagnetic ratio of the nucleus, Ω y Input the angular velocity into the system. We can get S∝l, so increasing the optical path can significantly increase the signal strength.

[0038] The system signal-to-noise ratio formula is:

[0039]

[0040] Among them, S signal is the signal of the system, S noise is the noise of the system. Therefore, when the system noise remains unchanged, increasing the signal strength can improve the signal-to-noise ratio.

[0041] The detection laser is incident on the alkali metal gas chamber B13, and after being reflected back and forth multiple times between the first optical cavity reflector B11 and the second optical cavity reflector B12 in the alkali metal gas chamber, it is incident on the fourth reflector B14 and the subsequent optical path, thereby achieving multiple reflections in the small volume of the alkali metal gas chamber. By adjusting the type of optical cavity reflectors, the number of optical cavity reflectors, the distance between the first optical cavity reflector B11 and the second optical cavity reflector B12, the relative position between the first optical cavity reflector B11 and the second optical cavity reflector B12, and the position and angle of the detection light incident on the alkali metal gas chamber B13, hundreds of reflections can be achieved in the small volume of the alkali metal gas chamber, which can significantly improve the intensity of the system output signal.

[0042] The first optical cavity reflector B11 and the second optical cavity reflector B12 are firstly strictly fixed on the silicon wafer B21 of the alkali metal gas chamber by means of anodic bonding. Specifically, the first optical cavity reflector B11 and the second optical cavity reflector B12 are installed on the silicon wafer B21 by means of a special mold which can determine the relative positions of the two. Under high temperature, high voltage and a certain pressure, an irreversible bonding reaction occurs at the connection between the reflector glass and the silicon wafer to form a strong silicon-oxygen bond, which firmly fixes the reflector on the silicon wafer B21. The silicon wafer B21 is then still fixed together with the gas chamber glass B22 by means of anodic bonding, so that the optical cavity is integrated inside the alkali metal gas chamber B13.

[0043] The first optical cavity reflector B11 and the second optical cavity reflector B12 are both cylinders with a positioning plane B24 and a light hole B23. The positioning plane B24 facilitates the determination of the relative rotation angle of the two optical cavity reflectors during bonding. The detection light enters from the light hole B23 of the first optical cavity reflector B11, and is emitted from the light hole B23 of the second optical cavity reflector B12 after multiple reflections. The number of reflections of the detection light in the optical cavity is determined by the design parameters of the type, relative rotation angle, distance, focal length, incident position and incident angle of the detection light of the two optical cavity reflectors. The position of the positioning plane B24 is determined by the design parameter of the relative rotation angle of the two optical cavity reflectors, and the position of the light hole B23 is determined by the design parameter of the incident position of the detection light.

[0044] The surfaces of the first optical cavity reflector B11 and the second optical cavity reflector B12 are coated with a high-temperature resistant high-reflective dielectric film B25 to ensure the reflection quality of the detection light. The first optical cavity reflector and the second optical cavity reflector can be spherical mirrors, cylindrical mirrors or plane mirrors. The type of the optical cavity reflector determines the reflection mode and the upper limit of the reflection times of the detection light in the optical cavity.

[0045] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in the field. It is pointed out here that the above description helps those skilled in the art to understand the invention, but does not limit the protection scope of the invention. Any equivalent replacement, modification and / or simplification of the above description without departing from the essence of the invention falls within the protection scope of the invention.

Claims

1. A SERF inertial measurement device based on optical cavity detection, comprising an alkali metal gas chamber, characterized in that: A multi-pass reflection optical cavity structure is arranged inside the alkali metal gas chamber, and the multi-pass reflection optical cavity structure comprises a first optical cavity reflector located at the incident side of the detection light and a second optical cavity reflector located at the emitting side of the detection light, the detection light input interface of the first optical cavity reflector guides the detection light from outside the alkali metal gas chamber to the reflection surface of the second optical cavity reflector, and the detection light is reflected back and forth on the two reflection surfaces to form multi-pass reflection, and then emitted from the detection light output interface of the second optical cavity reflector outside the alkali metal gas chamber.

2. The SERF inertial measurement device based on optical cavity detection according to claim 1, characterized in that: The optical cavity reflector is a spherical mirror, a cylindrical mirror or a plane mirror, the side of the optical cavity reflector has a positioning plane, and the detection light input interface and the detection light output interface are both light holes.

3. The SERF inertial measurement device based on optical cavity detection according to claim 1, characterized in that: The multi-pass reflection optical cavity structure comprises a silicon wafer bottom surface bonded to an alkali metal gas chamber bottom surface by anodic bonding, and the first optical cavity reflector and the second optical cavity reflector are both fixed to the silicon wafer bottom surface by anodic bonding.

4. The SERF inertial measurement device based on optical cavity detection according to claim 1, characterized in that: The alkali metal gas chamber is located in the non-magnetic heating module, the non-magnetic heating module is located in the three-axis compensation coil, the three-axis compensation coil is located in the zinc-manganese ferrite, and the zinc-manganese ferrite is located in the Permalloy magnetic shielding barrel.

5. The SERF inertial measurement device based on optical cavity detection according to claim 1, characterized in that: The detection light incident side of the alkali metal gas chamber is connected to the detection laser through the third reflector, the second reflector, the second 1 / 4 wave plate, the photoelastic modulator, the detection polarizer, the second aperture, the third lens, the second lens and the fourth Glan Taylor prism in sequence, and the detection light emitting side of the alkali metal gas chamber is connected to the host computer through the fourth reflector, the fifth reflector, the fourth lens, the detection polarizer, the second photodetector and the phase-locked amplifier module in sequence.

6. The SERF inertial measurement device based on optical cavity detection according to claim 5, characterized in that: The signal received by the host computer is: Among them, S is the output signal of the system, K1 is the amplification factor of the system for the optical rotation signal, θ is the optical rotation angle, n is the atomic number density in the gas chamber, c is the speed of light, r e is the electron radius, f D1 is a constant that characterizes the oscillator strength, l is the effective interaction length between the detection light and the atom, v is the detection laser frequency, ν0 is the center frequency of the absorption laser, Γ is the pressure broadening of the D1 line of the alkali metal atom, is the longitudinal polarizability of the electron, is the transverse relaxation rate of electrons, γ n is the electron gyromagnetic ratio, L z is the optical frequency shift, γ n is the gyromagnetic ratio of the nucleus, Ω y Enter the angular velocity for the system.

7. The SERF inertial measurement device based on optical cavity detection according to claim 1, characterized in that: The pumping light incident side of the alkali metal gas chamber is connected to the pumping laser through the first reflector, the first 1 / 4 wave plate, the first aperture, the third Glan Taylor prism, the second 1 / 2 wave plate, the second Glan Taylor prism, the liquid crystal phase retarder, the first Glan Taylor prism, the first 1 / 2 wave plate and the first lens in sequence, and the liquid crystal phase retarder is connected to the third Glan Taylor prism through the optical power stabilization module and the first photodetector in sequence.

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