An alkali metal atom polarization system based on holographic light field regulation

Abstract

The application discloses a kind of alkali metal atom polarization systems based on holographic light field regulation, which can realize the modulation of amplitude, phase and polarization of polarized light field simultaneously, increase the light field regulation capacity, and provide the basis for the development of high-precision atomic spin magnetic field measurement device, characterized by, including the holographic signal light path and the holographic reference light path arranged on the pumping light incident side of alkali metal cell, the first charge-coupled device and the second charge-coupled device arranged on the pumping light exit side of alkali metal cell, the holographic signal light is incident to the first charge-coupled device after passing through the alkali metal cell, the holographic reference light is emitted to the second charge-coupled device after crossing with the holographic signal light in the alkali metal cell, and the first charge-coupled device and the second charge-coupled device are respectively connected to the data acquisition and processing system.

Description

Technical Field

[0001] This invention relates to the fields of atomic spin magnetic field measurement and holography, and in particular to an alkali metal atom polarization system based on holographic light field modulation. By modulating the holographic light field, the amplitude, phase and polarization of the atomic polarization light field can be modulated simultaneously, providing a solution for efficient atomic polarization and serving the development of high-precision atomic spin magnetic field measurement devices. Background Technology

[0002] Atomic spin magnetic field measurement devices utilize the atomic spin effect to measure magnetic fields. Their theoretical accuracy limit is only related to quantum noise and fundamental physical constants, demonstrating the potential for ultra-high precision magnetic field measurement. They play a crucial role in fields such as human body magnetic field detection, magnetic anomaly detection, and resource exploration. These spin-based magnetic field measurement devices use alkali metal atoms as sensitive cores, achieving ultra-high precision magnetic field measurement by detecting the spin precession signals of polarized alkali metal atoms. Atomic spin polarization directly affects the final sensitivity and accuracy of the magnetic field measurement. Atomic spin polarization primarily relies on optical pumping technology. Under optical pumping, alkali metal atoms become polarized. Currently, polarization efficiency is mainly improved by optimizing parameters such as pump light quality, atomic ensemble ratio, and atomic density. However, the control methods are limited and difficult to control quickly and accurately. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing technologies by providing an alkali metal atom polarization system based on holographic light field modulation. This system can simultaneously modulate the amplitude, phase, and polarization of the polarization light field, thereby increasing the light field modulation capability and providing a foundation for the development of a high-precision atomic spin magnetic field measurement device.

[0004] The technical solution of the present invention is as follows:

[0005] A polarization system for alkali metal atoms based on holographic light field modulation is characterized by comprising a holographic signal light path and a holographic reference light path disposed on the incident side of the pump light in the alkali metal gas cell, and a first charge-coupled device and a second charge-coupled device disposed on the emitting side of the pump light in the alkali metal gas cell. The holographic signal light passes through the alkali metal gas cell and is incident on the first charge-coupled device. The holographic reference light crosses with the holographic signal light in the alkali metal gas cell and is emitted to the second charge-coupled device. The first charge-coupled device and the second charge-coupled device are respectively connected to a data acquisition and processing system.

[0006] The holographic signal light interferes with the holographic reference light to form a holographic polarized light field, which polarizes the alkali metal atoms.

[0007] The holographic signal light is connected to the transmission side of the polarization beam splitter in sequence through a first quarter-wave plate and an attenuator. The holographic reference light is connected to the reflection side of the polarization beam splitter in sequence through a second quarter-wave plate and a second reflecting mirror. The incident side of the polarization beam splitter is connected to the pump laser in sequence through a second half-wave plate and a spatial light modulator.

[0008] The spatial light modulator is a reflective spatial light modulator, which is connected to the pump laser in sequence through a first reflecting mirror, a polarizer, a first half-wave plate, and a beam expander.

[0009] The spatial light modulator is a transmissive spatial light modulator, which is connected to the pump laser in sequence through a polarizer, a first half-wave plate, and a beam expander.

[0010] The holographic signal light and the holographic reference light cross at an angle θ2 ≤ 5mrad, forming a holographic interference light field that modulates the atomic distribution within the alkali metal chamber.

[0011] The incident angle θ1 of the reflective spatial light modulator is ≤0.1 rad.

[0012] The second half-wave plate adjusts the polarization of the pump light, the polarization beam splitter outputs horizontally polarized holographic signal light and vertically polarized holographic reference light, the attenuator adjusts the intensity of the horizontally polarized holographic signal light, the first quarter-wave plate rotates to form holographic signal light of the desired polarization state and injects it into the alkali metal gas chamber, and the second quarter-wave plate rotates to form holographic reference light of the desired polarization state and injects it into the alkali metal gas chamber.

[0013] The technical effects of this invention are as follows: This invention is an alkali metal atom polarization system based on holographic light field modulation, comprising a pump laser, a beam expander, a first half-wave plate, a polarizer, a first reflector, a spatial light modulator, a second half-wave plate, a polarizing beam splitter, a second reflector, an attenuator, a first quarter-wave plate, a second quarter-wave plate, an alkali metal gas cell, a first charge-coupled device (CCD), a second CCD, and a data acquisition and processing system. The alkali metal gas cell is filled with alkali metal atoms. The phase and intensity distribution of the holographic pump light can be modulated by the spatial light modulator. The polarizing beam splitter divides the pump light into a holographic signal light and a holographic reference light. The polarization characteristics of the holographic signal light and the holographic reference light entering the alkali metal gas cell can be adjusted by rotating the quarter-wave plate. This invention combines holographic light field modulation with atomic light pumping, achieving nonlinear enhancement of atoms within the alkali metal gas cell through the holographic light field, improving the system's pump light field modulation capability, and enabling efficient atomic polarization. This provides a foundation for efficient polarization and precise control of atomic spin magnetic field measurement devices. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of an alkali metal atom polarization system based on holographic light field modulation, which implements the present invention.

[0015] Figure 2 This is another structural schematic diagram of an alkali metal atom polarization system based on holographic light field modulation, which implements the present invention.

[0016] The reference numerals in the attached diagram are explained as follows: 1-Pump laser; 2-Beam expander; 3-First half-wave plate; 4-Polarizer; 5-First reflecting mirror; 6-Spatial light modulator. Figure 1 The middle part is a reflective spatial light modulator. Figure 2 7-Second half-wave plate; 8-Polarizing beam splitter; 9-Second reflecting mirror; 10-Attenuator; 11-First quarter-wave plate; 12-Second quarter-wave plate; 13-Alkali metal gas cell; 14-First charge-coupled device; 15-Second charge-coupled device; 16-Data acquisition and processing system; θ1-Incident angle of incident light of reflective spatial light modulator; θ2-Intersection angle between holographic signal light and holographic reference light. Detailed Implementation

[0017] The following is in conjunction with the attached diagram ( Figures 1-2 The invention will be described in the following sections and examples.

[0018] Figure 1 This is a schematic diagram of the structure of an alkali metal atom polarization system based on holographic light field modulation, which implements the present invention. Figure 2 This is another structural schematic diagram of an alkali metal atom polarization system based on holographic light field modulation, which implements the present invention. (Reference) Figures 1 to 2 As shown, an alkali metal atom polarization system based on holographic light field modulation includes a holographic signal light path and a holographic reference light path arranged on the pump light incident side of an alkali metal gas cell 13, and a first charge-coupled device (CCD) 14 and a second charge-coupled device (CCD) 15 arranged on the pump light emitting side of the alkali metal gas cell 13. The holographic signal light passes through the alkali metal gas cell 13 and is incident on the first CCD 14. The holographic reference light intersects with the holographic signal light in the alkali metal gas cell 13 and is emitted to the second CCD 15. The first CCD 14 and the second CCD 15 are respectively connected to a data acquisition and processing system 16. The holographic signal light and the holographic reference light interfere to form a holographic polarization light field, which polarizes the alkali metal atoms.

[0019] The holographic signal light is sequentially connected to the transmission side of the polarizing beam splitter prism 8 via a first quarter-wave plate 11 and an attenuator 10. The holographic reference light is sequentially connected to the reflection side of the polarizing beam splitter prism 8 via a second quarter-wave plate 12 and a second reflecting mirror 9. The incident side of the polarizing beam splitter prism 8 is sequentially connected to the pump laser 1 via a second half-wave plate 7 and a spatial light modulator 6. The spatial light modulator 6 is a reflective spatial light modulator, which is sequentially connected to the pump laser 1 via a first reflecting mirror 5, a polarizer 4, a first half-wave plate 3, and a beam expander 2. Alternatively, the spatial light modulator 6 can be a transmissive spatial light modulator, which is sequentially connected to the pump laser 1 via a polarizer 4, a first half-wave plate 3, and a beam expander 2.

[0020] The holographic signal light and the holographic reference light cross at an angle θ2 ≤ 5 mrad, forming a holographic interference light field that modulates the atomic distribution within the alkali metal chamber. The incident angle of the incident light from the reflective spatial light modulator is θ1 ≤ 5 degrees. The second half-wave plate 7 adjusts the polarization of the pump light, the polarizing beam splitter 8 outputs horizontally polarized holographic signal light and vertically polarized holographic reference light, the attenuator 10 adjusts the intensity of the horizontally polarized holographic signal light, the first quarter-wave plate 11 rotates to form a holographic signal light of the desired polarization state that is incident into the alkali metal chamber 13, and the second quarter-wave plate 12 rotates to form a vertically polarized holographic reference light of the desired polarization state that is incident into the alkali metal chamber 13.

[0021] This invention discloses an alkali metal atom polarization system based on holographic light field modulation, such as... Figure 1 As shown, it includes a pump laser 1, a beam expander 2, a first half-wave plate 3, a polarizer 4, a first reflector 5, a spatial light modulator 6, a second half-wave plate 7, a polarizing beam splitter 8, a second reflector 9, an attenuator 10, a first quarter-wave plate 11, a second quarter-wave plate 12, an alkali metal gas cell 13, a first charge-coupled device 14, a second charge-coupled device 15, a data acquisition and processing system 16, an incident angle θ1 of the spatial light modulator, and an angle θ2 between the holographic signal light and the holographic reference light entering the gas cell.

[0022] The entire system works as follows:

[0023] The center wavelength of the linearly polarized light output from pump laser 1 corresponds to the center wavelength of the D1 line of alkali metal atoms in the pumped alkali metal gas cell 13. After the linearly polarized light is expanded by beam expander 2, the beam diameter input to alkali metal gas cell 13 is ensured to reach the matching size. The expanded pump light is adjusted by first half-wave plate 3 and matched with polarization of polarizer 4 to ensure that most of the light can pass through polarizer 4. Generally, it is horizontally or vertically polarized light, which is determined by the characteristics of spatial light modulator 6. The pump light passing through polarizer 4 is reflected by first mirror 5 and transmitted to reflective spatial light modulator 6 at a small angle θ1 (θ1 is less than 0.1 rad). After being modulated by spatial light modulator, the pump light is emitted with light carrying the corresponding amplitude and phase distribution. Depending on the modulation requirements, different types of spatial light modulators can be selected, such as amplitude, amplitude and phase, or pure phase type.

[0024] See Figure 2 If a transmissive spatial light modulator is used, the pump light through the polarizer 4 can be directly and perpendicularly incident into the spatial light modulator 6. After being modulated by the spatial light modulator, the pump light is emitted carrying light with corresponding amplitude and phase distribution.

[0025] The polarization of the light can be adjusted by the second half-wave plate 7. A certain proportion of horizontally polarized holographic signal light and vertically polarized holographic reference light are output through the polarizing beam splitter 8. The intensity of the horizontally polarized holographic signal light is adjusted by the attenuator 10. The desired polarization state of the holographic signal light is obtained by rotating the first quarter-wave plate 11 to form a certain angle, and then enters the alkali metal gas chamber 13. The vertically polarized holographic signal light is obtained by passing through the second quarter-wave plate 12 at a certain angle to form the desired polarization state of the holographic reference light, which is then entered into the alkali metal gas chamber 13. The alkali metal atomic medium has nonlinear properties. Due to its polarization properties, it can be used as a polarization holographic material. Therefore, the holographic signal light and the holographic reference light can be of the same polarization or different polarizations, which can be set according to the modulation requirements. The holographic signal light and the holographic reference light intersect at a small angle θ2 (θ2 is less than 5mrad) in the alkali metal gas cell 13 to form a holographic interference light field, which modulates the atomic distribution in the alkali metal gas cell 13. The emitted holographic signal light and holographic reference light are received by the first charge-coupled device 14 and the second charge-coupled device 15, respectively, and transmitted to the data acquisition and processing system 16 for analysis.

[0026] The technical effects of this invention are as follows: This invention provides an alkali metal atom polarization system based on holographic light field modulation. A holographic light field is formed by the interference of holographic signal light and holographic reference light in an alkali metal gas chamber. By modulating the spatial light modulator, the holographic signal light and holographic reference light can carry effective amplitude and phase information. Different amplitude, phase, and polarization distributions of holographic signal light and holographic reference light will form different holographic light fields in the holographic medium and form a certain diffraction. By observing the changes in the light field, the atomic polarization can be effectively controlled.

[0027] The advantages of this invention compared with the prior art are as follows: This invention can not only optimize polarization by optimizing parameters such as pump field quality, atomic ensemble ratio, and atomic density, but also enable more dimensional control of the pump field. Through the formation of a holographic field, this system can simultaneously control the amplitude, phase, and polarization of the pump field, greatly increasing the light field control capability and thus enabling efficient polarization, providing a foundation for the development of a high-precision atomic spin magnetic field measurement device.

[0028] A holographic light field-based alkali metal atom polarization system includes a pump laser 1, a beam expander 2, a first half-wave plate 3, a polarizer 4, a first reflector 5, a spatial light modulator 6, a second half-wave plate 7, a polarizing beam splitter 8, a second reflector 9, an attenuator 10, a first quarter-wave plate 11, a second quarter-wave plate 12, an alkali metal gas cell 13, a first charge-coupled device 14, a second charge-coupled device 15, and a data acquisition and processing system 16. The pump light emitted from the pump laser 1 passes through the beam expander 2, the first half-wave plate 3, the polarizer 4, and the first reflector 5, and then enters the spatial light modulator 6 at a small angle (less than 0.1 rad). After being modulated by the spatial light modulator, the pump light is emitted and passes through the second half-wave plate 7. The pump light is then split into a holographic signal light and a holographic reference light by the polarizing beam splitter 8 before entering the alkali metal gas cell 13.

[0029] The spatial light modulator 6 is a reflective type. If it is a transmissive spatial light modulator, the light emitted from the polarizer 4 can be directly and perpendicularly incident into it. The spatial light modulator 6 can be an amplitude type or a phase type. The light incident into the spatial light modulator carries amplitude or phase distribution information after being modulated by the spatial light modulator.

[0030] The holographic signal light is horizontally polarized light transmitted through the polarization beam splitter 8. The amplitude and intensity of the holographic signal light are controlled by the rotating attenuator 10. The desired polarized light is obtained by rotating the first quarter-wave plate 11 to form different angles and enter the alkali metal gas chamber 13.

[0031] The holographic reference light is vertically polarized light reflected by the polarizing beam splitter 8. It enters the alkali metal gas chamber 13 through the second reflecting mirror 9 and the second quarter-wave plate 12. By rotating the second quarter-wave plate 12, different angles are formed to obtain the desired polarized light entering the alkali metal gas chamber 13.

[0032] The holographic signal light and the holographic reference light enter the alkali metal gas chamber 13 at a small angle, less than or equal to 5 mrad, and intersect to form a holographic polarized light field within the alkali metal gas chamber 13. Through laser pumping, the outermost electron spins of a large number of alkali metal atoms are macroscopically polarized.

[0033] The holographic signal light and holographic reference light are emitted from the alkali metal gas chamber 13 and then enter the first charge-coupled device 14 and the second charge-coupled device 15, respectively. The light signals entering the image sensor of the charge-coupled device are converted into analog current signals and sent to the data acquisition and processing system 16 for processing and analysis.

[0034] The alkali metal gas chamber 13 contains alkali metal atoms and a buffer gas. The alkali metal atoms are the working atoms and have nonlinear characteristics. The buffer gas consists of an inert gas and nitrogen, which are used to suppress bubble wall collision relaxation and reduce radiation capture.

[0035] An alkali metal atom polarization system based on holographic light field modulation is disclosed. The system comprises a pump laser 1, a beam expander 2, a first half-wave plate 3, a polarizer 4, a first reflector 5, a spatial light modulator 6, a second half-wave plate 7, a polarizing beam splitter 8, a second reflector 9, an attenuator 10, a first quarter-wave plate 11, a second quarter-wave plate 12, an alkali metal gas cell 13, a first charge-coupled device 14, a second charge-coupled device 15, and a data acquisition and processing system 16. The pump light emitted by the pump laser is expanded by the beam expander 2 and then polarized by the first half-wave plate 3 and the polarizer 4. After being reflected by the first reflector 5, the polarized light is incident on the spatial light modulator 6 at a small angle. The reflected pump light is split into two paths, a holographic signal light and a holographic reference light, by the second half-wave plate 7 and the polarizing beam splitter 8. The two paths converge in the alkali metal gas cell 13 and then exit. The emitted light field distribution is received by the first charge-coupled device 14 and the second charge-coupled device 15 and transmitted to the data acquisition and processing system 16.

[0036] The matched polarized light is determined by the characteristics of the spatial light modulator 6, and is usually horizontally polarized or vertically polarized.

[0037] The spatial light modulator 6 is a reflective type. If the spatial light modulator is a transmissive type, then the first reflecting mirror 5 is not required for reflection, and the matched polarized light can be directly incident perpendicularly on the spatial light modulator 6.

[0038] The pump light is modulated by the spatial light modulator 6, which writes the phase or amplitude information into the light wave. The pump light output by reflection carries the required phase or amplitude information.

[0039] The alkali metal gas chamber 13 is filled with alkali metal atoms, which are the working atoms and have nonlinear characteristics, making them suitable as holographic materials.

[0040] After the holographic signal light and the holographic reference light converge in the alkali metal gas chamber 13, the interference of the holographic signal light and the holographic reference light forms a holographic polarized light field, which polarizes the alkali metal atoms.

[0041] The first charge-coupled device 14 receives the light field distribution of the holographic signal light after the alkali metal atoms are polarized, and the second photodetector 15 receives the light field distribution of the holographic reference light after the alkali metal atoms are polarized. The data is then processed by the data acquisition and processing system.

[0042] Contents not described in detail in this specification are prior art known to those skilled in the art. It is hereby indicated that the above description is intended to help those skilled in the art understand this invention, but does not limit the scope of protection of this invention. Any equivalent substitutions, modifications, improvements, and / or simplifications of the above descriptions that do not depart from the essential content of this invention fall within the scope of protection of this invention.

Claims

1. A polarization system for alkali metal atoms based on holographic light field modulation, characterized in that, The system includes a holographic signal light path and a holographic reference light path set on the incident side of the pump light in the alkali metal gas cell, and a first charge-coupled device and a second charge-coupled device set on the emitting side of the pump light in the alkali metal gas cell. The holographic signal light passes through the alkali metal gas cell and is incident on the first charge-coupled device. The holographic reference light crosses with the holographic signal light in the alkali metal gas cell and is emitted to the second charge-coupled device. The first charge-coupled device and the second charge-coupled device are respectively connected to a data acquisition and processing system. The holographic signal light is connected to the transmission side of the polarization beam splitter in sequence through a first quarter-wave plate and an attenuator. The holographic reference light is connected to the reflection side of the polarization beam splitter in sequence through a second quarter-wave plate and a second reflecting mirror. The incident side of the polarization beam splitter is connected to the pump laser in sequence through a second half-wave plate and a spatial light modulator. The second half-wave plate adjusts the polarization of the pump light, the polarization beam splitter outputs horizontally polarized holographic signal light and vertically polarized holographic reference light, the attenuator adjusts the intensity of the horizontally polarized holographic signal light, the first quarter-wave plate rotates to form holographic signal light of the desired polarization state and injects it into the alkali metal gas chamber, and the second quarter-wave plate rotates to form vertically polarized holographic reference light of the desired polarization state and injects it into the alkali metal gas chamber.

2. The alkali metal atom polarization system based on holographic light field modulation according to claim 1, characterized in that, The holographic signal light interferes with the holographic reference light to form a holographic polarized light field, which polarizes the alkali metal atoms.

3. The alkali metal atom polarization system based on holographic light field modulation according to claim 1, characterized in that, The spatial light modulator is a reflective spatial light modulator, which is connected to the pump laser in sequence through a first reflecting mirror, a polarizer, a first half-wave plate, and a beam expander.

4. The alkali metal atom polarization system based on holographic light field modulation according to claim 1, characterized in that, The spatial light modulator is a transmissive spatial light modulator, which is connected to the pump laser in sequence through a polarizer, a first half-wave plate, and a beam expander.

5. The alkali metal atom polarization system based on holographic light field modulation according to claim 1, characterized in that, The holographic signal light and the holographic reference light cross at an angle θ2 ≤ 5mrad, forming a holographic interference light field that modulates the atomic distribution within the alkali metal chamber.

6. The alkali metal atom polarization system based on holographic light field modulation according to claim 3, characterized in that, The incident angle θ1 of the reflective spatial light modulator is ≤0.1 rad.

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