A cesium beam atomic clock based on double laser pumping of a faraday laser

Abstract

The application discloses a double-laser pumped cesium beam atomic clock based on a Faraday laser, which comprises a first Faraday laser, a second Faraday laser, a cesium oven, a microwave cavity, a fluorescence collector, a cesium clock locking circuit and a microwave signal source. 2 S 1 / 2 (F=4)→6 2 P 3 / 2 (F’=5) is locked on the cesium atom 6 2 S 1 / 2 (F=3)→6 2 P 3 / 2 (F’=2) is obtained after frequency shifting, and is used as the 3-3' pi polarized second pumping light; under the action of the two pumping lights, the atoms are uniformly distributed in seven sub-energy levels of the ground state F=3 when pumped by single light, and are converted into mainly gathering on the ground state F=3, m F =0 sub-energy level, the signal-to-noise ratio of the clock signal is greatly improved, and excellent frequency stability is obtained after the cesium clock is locked.

Description

Technical Field

[0001] This invention belongs to the field of quantum frequency standards, specifically relating to a dual-laser pumped cesium beam atomic clock based on a Faraday laser. Background Technology

[0002] Atomic clocks have significant application value in both basic research and practical fields. Due to their remarkably superior performance, optical atomic clocks have been extensively and deeply studied in recent years, with the best-performing optical clocks currently achieving system uncertainties on the order of E-19. However, cesium beam atomic microwave clocks possess more mature integration capabilities and remain irreplaceable as the standard for defining the second. Traditional cesium beam clocks employ two atomic preparation methods: optical pumping and magnetic state selection. The former uses laser pumping to prepare atoms into a single hyperfine level of the ground state, while the latter selects atoms into a single hyperfine level by applying a gradient magnetic field to the preparation region. The optical pumping scheme offers higher beam intensity and pump efficiency compared to the magnetic state selection scheme, thus allowing for more efficient use of atoms. However, after single-laser pumping, atoms are distributed across various sub-levels of the ground state, resulting in insufficient atom utilization. Using two optical pumps holds promise for focusing all atoms into one ground state m. F The pump is applied to the zero sublevel, thus effectively increasing the signal strength. Previous experiments have observed the pump effect, but the signal-to-noise ratio did not increase with the increase of amplitude; instead, it decreased. Summary of the Invention

[0003] To improve the signal-to-noise ratio and frequency stability of traditional laser-pumped cesium beam atomic clocks, this invention proposes a dual-laser-pumped cesium beam atomic clock using a Faraday laser as the light source, which pumps atoms to the ground state F = 3,m. F On a single magnetic level where 0 = 0, improve the signal-to-noise ratio of the clock signal and the frequency stability after locking.

[0004] This invention employs a Faraday laser stabilized by modulation-transfer spectrum technology as the light source. Dual-laser pumping is achieved by precisely controlling the polarization of two pump lasers, accumulating atoms on a single magnetic sublevel. Because the Faraday laser has a narrower linewidth and lower frequency noise compared to a laser diode, it can significantly improve the signal-to-noise ratio of the clock signal, thereby enhancing the stability of the cesium clock.

[0005] Based on the above ideas, this invention provides a miniature cesium beam atomic clock using dual Faraday laser pumping, employing the following technical solution:

[0006] A dual-laser-pumped cesium beam atomic clock based on a Faraday laser, characterized in that it comprises a first Faraday laser 1001, a second Faraday laser 1002, a cesium furnace 1020, a microwave cavity 1021, a fluorescence collector 1005, a cesium clock locking circuit 1022, and a microwave signal source 1023; wherein,

[0007] The first Faraday laser 1001 is used to lock the output laser frequency at the cyclic transition line 6 of cesium atoms. 2 S 1 / 2 (F=4)→6 2 P 3 / 2 (F'=5) and split into two beams by a beam splitter unit. One beam is used as the probe light, and the other beam is obtained as the first pump light after frequency shifting and polarization adjustment, which is used to pump cesium atoms to the ground state F=3.

[0008] The second Faraday laser 1002 is used to lock the output laser frequency at the cesium atom cyclic transition line 6. 2 S 1 / 2 (F=3)→6 2 P 3 / 2 (F'=2), and after frequency shifting and polarization adjustment, a second pump light is obtained, which is used to pump cesium atoms to the ground state F=3, m F At the magnetic level where 0 = 0;

[0009] The cesium furnace 1020 is used to generate cesium atoms and input them into the microwave cavity 1021; wherein, under the action of the first pump light, the cesium atoms output from the cesium furnace 1020 are pumped from the ground state F=4 to the ground state F=3 energy level; and under the action of the second pump light, atoms of other magnetic sublevels on the ground state F=3 energy level are prepared to the ground state F=3,m F At the magnetic level where 0 = 0;

[0010] The microwave signal source 1023 is used to generate microwaves with a frequency corresponding to the clock transition frequency and inject them into the microwave cavity 1021. Cesium atoms in the microwave cavity 1021 undergo transitions under the action of microwaves, transitioning from the ground state F=3 to the ground state F=4. Under the action of the probe light, the atoms in the ground state F=4 are excited to the upper energy level F=5'.

[0011] The fluorescence collector 1005 is used to detect the fluorescent photons generated when the upper energy level F=5' falls to the ground state F=4, thereby obtaining the clock transition spectral line signal;

[0012] The cesium clock locking circuit 1022 is used to lock the frequency of the microwave at the clock transition frequency.

[0013] Furthermore, as one option, the first pump light has a frequency corresponding to 6. 2 S 1 / 2 (F=4)→6 2 P 3 / 2 (F'=4) A laser with a transition frequency and polarization state of σ polarization; the second pump light has a frequency corresponding to 6. 2 S 1 / 2(F=3)→6 2 P 3 / 2 (F'=3) A laser with a transition frequency and a polarization state of π.

[0014] As an alternative solution, the first pump light has a frequency corresponding to 6. 2 S 1 / 2 (F=4)→6 2 P 3 / 2 (F'=3) A laser with a transition frequency and polarization state of σ polarization, and the second pump light has a frequency corresponding to 6. 2 S 1 / 2 (F=3)→6 2 P 3 / 2 (F'=3) A laser with a transition frequency and a polarization state of π.

[0015] Furthermore, taking Scheme 1 as an example, the laser output from the first Faraday laser 1001 is split into two beams after passing through the first half-wave plate 1003 and the first polarizing beam splitter 1004. The transmitted light serves as the probe light, and the reflected light is incident on the first acousto-optic modulator 1007 after being narrowed by the first lens 1006 for frequency shifting. Then, it is collimated by the second lens 1008 and output. The zero-order light and +1-order diffracted light output after collimation by the second lens 1008 are blocked by the first shield 1009. The light after frequency shifting by the first acousto-optic modulator 1007 is reflected by the first mirror 1010 and then adjusted into σ light by the second half-wave plate 1011 before entering the pump region through the beam combiner 1019.

[0016] Furthermore, the laser output from the second Faraday laser 1002 is sequentially incident on the second acousto-optic modulator 1014 via the second reflecting mirror 1012 and the third lens 1013, and then output via the fourth lens 1015. The zero-order light and the -1st order diffracted light output from the fourth lens 1015 are blocked by the second shielding object 1016. The light after frequency shifting by the second acousto-optic modulator 1014 is adjusted into π light by the third half-wave plate 1017 and then sequentially passes through the third reflecting mirror 1018 and the beam combiner 1019 to coincide with the first pump light and enter the pump region.

[0017] Furthermore, a coil is wound on the microwave cavity 1021 to generate a magnetic field that eliminates energy level degeneracy, and the microwave cavity 1021 is magnetically shielded using a double layer of permalloy.

[0018] Furthermore, a three-dimensional helium-Möller coil is added to the pump region to shield the ambient magnetic field of the pump region and to control the quantization axis of the polarization of the first pump light and the second pump light.

[0019] As an alternative, a six-stage magnetic field can be set up in the pumping zone to focus the selected atoms, thereby improving the utilization rate of the atoms.

[0020] As an alternative, the first Faraday laser 1001 is used to lock the output laser frequency at the cyclic transition line 6 of cesium atoms. 2 S 1 / 2 (F=3)→6 2 P 3 / 2 The laser beam is split into two beams at (F'=2), one of which serves as the probe beam, and the other, after frequency shifting and polarization adjustment, becomes the first pump beam, used to pump cesium atoms to the ground state F=4; the second Faraday laser 1002 is used to lock the output laser frequency at the cesium atom cyclic transition line 6. 2 S 1 / 2 (F=4)→6 2 P 3 / 2 (F'=5), and after frequency shifting and polarization adjustment, a second pump light is obtained, which is used to pump cesium atoms to the ground state F=4, m F The cesium furnace 1020 is used to generate cesium atoms and input them into the microwave cavity 1021; wherein, under the action of the first pump light, the cesium atoms output from the cesium furnace 1020 are pumped from the ground state F=3 to the ground state F=4 energy level; and under the action of the second pump light, atoms from other magnetic sub-levels on the ground state F=4 energy level are prepared to the ground state F=4,m F The microwave signal source 1023 is used to generate microwaves with a frequency corresponding to the clock transition frequency and inject them into the microwave cavity 1021. Cesium atoms in the microwave cavity 1021 undergo transitions under the action of microwaves, transitioning from the ground state F=4 to the ground state F=3. Under the action of the probe light, the atoms in the ground state F=3 are excited to the upper energy level F=2'. The fluorescence collector 1005 is used to detect the fluorescent photons generated when falling from the upper energy level F=2' to the ground state F=3, thereby obtaining the clock transition spectral line signal. The cesium clock locking circuit 1022 is used to lock the frequency of the microwaves to the clock transition frequency.

[0021] Furthermore, as a third option, the first pump light has a frequency corresponding to 6. 2 S 1 / 2 (F=3)→6 2 P 3 / 2 (F'=4) A laser with a transition frequency and polarization state of π; the second pump light has a frequency corresponding to 6. 2 S 1 / 2 (F=4)→6 2 P 3 / 2 (F'=4) A laser with a transition frequency and a polarization state of π; the probe light has a frequency corresponding to 6. 2 S 1 / 2 (F=3)→6 2 P 3 / 2 (F'=2) Transition frequency.

[0022] As a fourth option, the first pump light has a frequency corresponding to 6. 2 S 1 / 2 (F=3)→6 2 P 3 / 2 (F'=3) A laser with a transition frequency and polarization state of σ polarization, and the second pump light has a frequency corresponding to 6. 2 S 1 / 2 (F=4)→6 2 P 3 / 2 (F'=4) A laser with a transition frequency and a polarization state of π; the probe light has a frequency corresponding to 6. 2 S 1 / 2 (F=3)→6 2 P 3 / 2 (F'=2) Transition frequency.

[0023] As a fifth option, the first pump light has a frequency corresponding to 6. 2 S 1 / 2 (F=3)→6 2 P 3 / 2 (F'=4) A laser with a transition frequency and polarization state of σ polarization, and the second pump light has a frequency corresponding to 6. 2 S 1 / 2 (F=4)→6 2 P 3 / 2 (F'=4) A laser with a transition frequency and a polarization state of π; the probe light has a frequency corresponding to 6. 2 S 1 / 2 (F=3)→6 2 P 3 / 2 (F'=2) Transition frequency.

[0024] The dual Faraday laser-pumped cesium beam atomic clock of the present invention includes an optical system and a circuit system. The optical system mainly includes two Faraday laser sources for generating pump and probe light, namely a first Faraday laser 1001 and a second Faraday laser 1002; a cesium furnace 1020 for generating cesium atoms; a microwave cavity 1021 providing the microwave-atom interaction region; and a fluorescence collector 1005 for signal detection. The circuit system mainly includes a cesium clock locking circuit 1022 and a microwave signal source 1023.

[0025] Taking Scheme 1 as an example, the first Faraday laser 1001 uses modulation transfer spectrum frequency stabilization technology to lock the output laser frequency at the cyclic transition line 6 of cesium atoms. 2 S 1 / 2 (F=4)→6 2 P 3 / 2The electron beam (F'=5) is split into two beams. One beam serves as the probe beam, interacting with atoms in the detector region of the cesium beam tube to excite atoms in the F=4 state after microwave interaction, generating a fluorescence signal, which is collected and detected by the fluorescence collector 1005. The other beam, after being frequency-shifted by an acousto-optic modulator to -251.1MHz, serves as the first pump beam, with a frequency corresponding to 6. 2 S 1 / 2 (F=4)→6 2 P 3 / 2 The (F'=4) transition adjusts its polarization state to σ polarization, which is used to pump cesium atoms to the ground state F=3; the second Faraday laser 1002 also uses modulation transfer spectrum stabilization technology to lock the output laser frequency at the cesium atom cyclic transition line 6. 2 S 1 / 2 (F=3)→6 2 P 3 / 2 On (F'=2), an acousto-optic modulator is used to shift the frequency by 151.2MHz as the second pump light, whose frequency corresponds to 6. 2 S 1 / 2 (F=3)→6 2 P 3 / 2 The (F'=3) transition adjusts its polarization state to π polarization, which is used to pump cesium atoms to the ground state F=3, m F At the magnetic level where =0.

[0026] After cesium atoms are collimated and ejected from a heated cesium furnace 1020, they are excited to the F'=4 state by the first pump light with σ polarization during the 4-4' transition. After spontaneous emission decay to the ground states F=3 and F=4, the atoms in the F=4 state are repeatedly excited by the first pump light. After multiple cycles, almost all atoms are pumped to the ground state F=3 energy level, achieving the initial preparation of the atomic state. At this point, the atoms are uniformly distributed across seven magnetic sublevels: F=3, mF=-3, ..., 3.

[0027] Furthermore, since the π-polarized light undergoing the 3-3' transition is a forbidden transition, i.e., F = 3, m F =0→F'=3,m F Since the transition probability between magnetic sublevels with energy level = 0 is 0, under the action of the second pump light, atoms in the other six magnetic sublevels are pumped out, and atoms are prepared to the ground state F = 3 to the maximum extent. F At the magnetic level where =0.

[0028] The microwave signal source 1023 generates a frequency of 9.192 GHz (corresponding to the clock transition frequency, i.e., F = 3m). F =0→F=4,m FMicrowaves (F=0) are injected into microwave cavity 1021. Atoms undergo transitions under the influence of the microwaves, transitioning from the ground state F=3 to F=4. Under the action of the probe light for the 4-5' transition, the F=4 atom is excited to the upper energy level F=5'. Upon falling back to the ground state F=4, it decays, producing fluorescent photons, which are collected and detected by fluorescence collector 1005, thus obtaining the clock transition spectral signal. Under the action of cesium clock locking circuit 1022, the frequency of the microwave signal is locked to the clock transition frequency.

[0029] Furthermore, other alternative dual-light pump laser frequency schemes exist, such as using 4→3'σ and 3→3'π as pumps and 4→5' as detectors; 3→4'π and 4→4'π as pumps and 3→2' as detectors; 3→3'σ and 4→4'π as pumps and 3→2' as detectors; and 3→4'σ and 4→4'π as pumps and 3→2' as detectors, etc. All of these utilize forbidden transitions of 3→3'π and 4→4'π to prepare atoms at a single ground-state magnetic level.

[0030] Furthermore, in order to detect F=3,m F =0→F=4,m F A clock signal of 0 generates a weak magnetic field (i.e., C field) in a coil wound around a microwave cavity to eliminate the degeneracy of energy levels.

[0031] Furthermore, in order to overcome the influence of Zeeman frequency shift caused by magnetic field fluctuations on stability, a double-layer permalloy is used to magnetically shield the microwave cavity.

[0032] Furthermore, in order to shield the ambient magnetic field of the pump region and simultaneously generate a quantized axis to regulate the polarization of the two pump beams, a three-dimensional helium-Möhler coil is added to the pump region for precise magnetic field control.

[0033] Furthermore, to further improve the utilization rate of atoms, a six-stage magnetic focusing scheme can be used in the pump region to focus the atoms and enhance the signal strength. By setting up a six-stage magnet in the pump region, the selected atoms are further focused, thereby improving the utilization rate of atoms.

[0034] Compared with existing technologies, the positive effects of the dual Faraday laser-pumped cesium beam atomic clock proposed in this invention are as follows:

[0035] Traditional laser-pumped cesium beam atomic clocks use a laser beam as the pump light to pump atoms to a hyperfine level of the cesium atom's ground state, which serves as the clock transition signal. FOnly a portion of atoms (15%) are in the =0 sub-level, thus the utilization rate of atoms remains limited. The dual-Faraday laser-pumped cesium beam atomic clock has two significant advantages: firstly, by setting a precisely adjusted three-dimensional magnetic field in the pump region, two laser beams of different frequencies with specific polarizations can be used as pump light, ideally allowing atoms to be completely prepared to the ground state m. F At the 0 sublevel, the atomic utilization rate is increased from 15% in the traditional optical pump scheme to a theoretically over 90%, resulting in a larger clock transition signal amplitude. Secondly, a narrow-linewidth, high-frequency-stability Faraday laser is used as the light source, which has lower frequency noise compared to traditional laser tubes and DFB / DBR lasers, solving the problem of poor signal-to-noise ratio in traditional dual-optical pump schemes. This achieves, for the first time, a dual-laser pumped cesium beam clock with high signal-to-noise ratio and high frequency stability. In summary, the dual-Faraday laser pumped cesium beam atomic clock has a higher signal-to-noise ratio, thus enabling better frequency stability. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of a dual Faraday laser-pumped cesium beam atomic clock.

[0037] Among them, 1001-first Faraday laser; 1002-second Faraday laser; 1003-first half-wave plate; 1004-polarizing beam splitter; 1005-fluorescence collector; 1006-first lens; 1007-first acousto-optic modulator; 1008-second lens; 1009-first obstruction; 1010-first reflector; 1011-second half-wave plate; 1012-second reflector; 1013-third lens; 1014-second acousto-optic modulator; 1015-fourth lens; 1016-second obstruction; 1017-third half-wave plate; 1018-third reflector; 1019-beam combiner; 1020-cesium furnace; 1021-microwave cavity; 1022-cesium clock locking circuit; 1023-microwave signal source.

[0038] Figure 2 This is a diagram of the relevant energy level structure of a dual Faraday laser-pumped cesium beam atomic clock. Detailed Implementation

[0039] The following examples are used to explain the technical solutions of the present invention in a non-limiting manner.

[0040] The structure of a dual Faraday laser-pumped cesium beam atomic clock is as follows: Figure 1 As shown, it mainly includes two laser sources for generating pump and probe light: the first Faraday laser 1001 is locked to cesium atoms using modulation-transfer spectrum stabilization technology. 2 S 1 / 2 (F=4)→6 2 P 3 / 2(F'=5) serves as the probe light and the first pump light obtained after frequency shifting; the second Faraday laser 1002 also employs modulation transfer spectrum stabilization technology to lock onto cesium atoms 6. 2 S 1 / 2 (F=3)→6 2 P 3 / 2 (F'=2) is used as the second pump light after frequency shifting. The specific optical path structure is as follows:

[0041] After frequency stabilization by the first Faraday laser 1001, the light is split into two beams by the first half-wave plate 1003 and the first polarizing beam splitter 1004. The transmitted light serves as the probe light, detecting atoms in the ground state F=4 energy level, and the resulting fluorescence signal is detected by the fluorescence collector 1005. The reflected light is then focused by the first lens 1006 and fed into the first acousto-optic modulator 1007, where it is shifted to -251.1MHz (-1st order diffraction light). After collimation by the second lens 1008, the light is output. The zeroth order and +1st order diffraction light are blocked by the first shield 1009. The frequency of the shifted light corresponds to the 4-4' transition of the cesium atom (i.e., 6-4'). 2 S 1 / 2 (F=4)→6 2 P 3 / 2 The first pump light (F'=4) is reflected by the first mirror 1010 and then enters the pump region through the combiner 1019. The polarization state of the first pump light is adjusted to σ light by the second half-wave plate 1011. After the second Faraday laser 1002 is frequency stabilized, it is reflected by the second mirror 1012 and then frequency-shifted by 151.2MHz (+1st order diffraction light) by the combination of the third lens 1013, the second acousto-optic modulator 1014, and the fourth lens 1015, and then output as the second pump light. The zeroth order light and the -1st order diffraction light are blocked by the second shield 1016. After being reflected by the third mirror 1018 and the combiner 1019, the second pump light coincides with the first pump light and enters the pump region. Its polarization state is adjusted to π light by the third half-wave plate 1017.

[0042] After being collimated and ejected from a heated cesium furnace (1020), cesium atoms accumulate to their ground state F = 3,m under the influence of a first pump beam with σ polarization and a second pump beam with π polarization. F At the sub-energy level of F=0. A microwave signal source 1023 generates microwaves with a frequency of 9.192 GHz, which are injected into the microwave cavity 1021. Under the influence of the microwaves, atoms undergo transitions from the ground state F=3 to F=4. Under the action of the probe light of the 4-5' transition, the atoms are excited to the upper energy level, decay to produce fluorescent photons, and are detected by the fluorescence collector 1005, thus obtaining the clock transition spectral signal. Under the action of the cesium clock locking circuit 1022, the frequency of the microwave signal is locked to the clock transition frequency.

[0043] Furthermore, in order to detect F=3,mF =0→F=4,m F A clock signal equal to 0 generates a C-field in a coil wound around a microwave cavity to eliminate the degeneracy of energy levels;

[0044] Furthermore, in order to overcome the influence of Zeeman frequency shift caused by magnetic field fluctuations on stability, the microwave cavity is magnetically shielded.

[0045] Furthermore, in order to shield the ambient magnetic field of the pump region and generate a quantization axis that regulates the polarization of the pump light, a three-dimensional helium-Möller coil is added to the pump region for magnetic field control.

[0046] Furthermore, in order to further improve the utilization rate of atoms, a six-stage magnetic focusing scheme can be used to focus atoms and enhance signal strength.

[0047] Under the influence of two pump beams, atoms are uniformly distributed in the ground state F=3 when pumped by a single beam. F The seven sub-levels of F = -3...3 are transformed into a state where the energy is mainly concentrated in the ground state F = 3, m F At the 0 sublevel, the signal-to-noise ratio of the clock signal is greatly improved, resulting in excellent frequency stability after cesium clock locking.

[0048] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Without departing from the spirit and scope of the appended claims, those skilled in the art can modify or make equivalent substitutions to the technical solutions of the present invention. Therefore, the present invention should not be limited to the content disclosed in the embodiments, and the specific scope of protection is determined by the scope defined in the claims.

Claims

1. A dual-laser-pumped cesium beam atomic clock based on a Faraday laser, characterized in that, It includes a first Faraday laser (1001), a second Faraday laser (1002), a cesium furnace (1020), a microwave cavity (1021), a fluorescence collector (1005), a cesium clock locking circuit (1022), and a microwave signal source (1023); among which, The first Faraday laser (1001) is used to lock the output laser frequency at the cyclic transition line 6 of the cesium atom. 2 S 1 / 2 ( F =4)→6 2 P 3 / 2 ( F’ =5), and then split into two beams by a beam splitter. One beam is used as the probe beam, and the other beam, after frequency shifting and polarization adjustment, becomes the first pump beam, which is used to pump cesium atoms to the ground state. F =3 on; The second Faraday laser (1002) is used to lock the output laser frequency at the cesium atom cyclic transition line 6. 2 S 1 / 2 ( F =3)→6 2 P 3 / 2 ( F’ =2), and after frequency shifting and polarization adjustment, a second pump light is obtained, which is used to pump cesium atoms to the ground state. F =3,m F At the magnetic sublevel where =0; The cesium furnace (1020) is used to generate cesium atoms and input them into the microwave cavity (1021); wherein, the cesium atoms output from the cesium furnace (1020) are in their ground state under the action of the first pump light. F Atoms with a =4 are pumped to the ground state. F =3 energy level; and under the action of the second pump light, the ground state F Atoms in other magnetic sublevels at level 3 are prepared to the ground state. F =3, m F At the magnetic sublevel where =0; The microwave signal source (1023) is used to generate microwaves with a frequency corresponding to the clock transition frequency and inject them into the microwave cavity (1021). Cesium atoms in the microwave cavity (1021) undergo transitions under the action of microwaves, moving from the ground state. F =3 transitions to the ground state F =4, and under the action of the probe light, the ground state... F Atoms with a density of 4 are excited to the upper energy level. F =5'; The fluorescence collector (1005) is used to detect fluorescence from the upper energy level. F =5' falls to the ground state F The fluorescent photons generated when =4 are used to obtain the clock transition spectral line signal; The cesium clock locking circuit (1022) is used to lock the frequency of the microwave at the clock transition frequency; The first pump light corresponds to a frequency of 6. 2 S 1 / 2 ( F =4)→6 2 P 3 / 2 ( F’ =4) A laser with a transition frequency and polarization state of σ polarization, and the second pump light has a frequency corresponding to 6. 2 S 1 / 2 ( F =3)→6 2 P 3 / 2 ( F’ =3) A laser with a transition frequency and polarization state of π; or the first pump light has a frequency corresponding to 6 2 S 1 / 2 ( F =4)→6 2 P 3 / 2 ( F’ =3) A laser with a transition frequency and polarization state of σ polarization, and the second pump light has a frequency corresponding to 6. 2 S 1 / 2 ( F =3)→6 2 P 3 / 2 ( F’ =3) Lasers with transition frequency and polarization state of π polarization.

2. The dual-laser pumped cesium beam atomic clock according to claim 1, characterized in that, The laser output from the first Faraday laser (1001) is split into two beams after passing through the first half-wave plate (1003) and the first polarizing beam splitter (1004). The transmitted light is used as the probe light, and the reflected light is compressed by the first lens (1006) and then incident on the first acousto-optic modulator (1007) for frequency shifting. After being collimated by the second lens (1008), it is output. The zero-order light and +1-order diffracted light output by the second lens (1008) are blocked by the first shield (1009). The light after frequency shifting by the first acousto-optic modulator (1007) is reflected by the first mirror (1010) and then adjusted by the second half-wave plate (1011) into σ light, which enters the pump region through the beam combiner (1019).

3. The dual-laser pumped cesium beam atomic clock according to claim 1, characterized in that, The laser output from the second Faraday laser (1002) is incident on the second acousto-optic modulator (1014) through the second mirror (1012) and the third lens (1013) in sequence. After frequency shifting, it is output through the fourth lens (1015). The zero-order light and -1-order diffracted light output from the fourth lens (1015) are blocked by the second shield (1016). The light after frequency shifting by the second acousto-optic modulator (1014) is adjusted to π light by the third half-wave plate (1017) and then passes through the third mirror 1018 and the beam combiner (1019) in sequence to coincide with the first pump light and enter the pump region.

4. The dual-laser pumped cesium beam atomic clock according to claim 1, characterized in that, A six-level magnetic field is set in the pumping zone to focus the atoms after the selection state; a coil is wound on the microwave cavity (1021) to generate a magnetic field to eliminate energy level degeneracy, and a double layer of permalloy is used to magnetically shield the microwave cavity (1021).

5. The dual-laser pumped cesium beam atomic clock according to claim 1, characterized in that, A three-dimensional helium-Möhler coil is added to the pump region to shield the ambient magnetic field of the pump region and to control the quantization axis of the polarization of the first pump light and the second pump light.

6. A dual-laser-pumped cesium beam atomic clock based on a Faraday laser, characterized in that, It includes a first Faraday laser (1001), a second Faraday laser (1002), a cesium furnace (1020), a microwave cavity (1021), a fluorescence collector (1005), a cesium clock locking circuit (1022), and a microwave signal source (1023); among which, The first Faraday laser (1001) is used to lock the output laser frequency at the cyclic transition line 6 of the cesium atom. 2 S 1 / 2 ( F =3)→6 2 P 3 / 2 ( F’ =2), and then split into two beams by a beam splitter. One beam is used as the probe beam, and the other beam, after frequency shifting and polarization adjustment, becomes the first pump beam, which is used to pump cesium atoms to the ground state. F =4 above; The second Faraday laser (1002) is used to lock the output laser frequency at the cesium atom cyclic transition line 6. 2 S 1 / 2 ( F =4)→6 2 P 3 / 2 ( F’ =5), and after frequency shifting and polarization adjustment, a second pump light is obtained, which is used to pump cesium atoms to the ground state. F =4,m F At the magnetic sublevel where =0; The cesium furnace (1020) is used to generate cesium atoms and input them into the microwave cavity (1021); wherein, the cesium atoms output from the cesium furnace (1020) are in their ground state under the action of the first pump light. F Atoms with a value of 3 are pumped to the ground state. F =4 energy level; and under the action of the second pump light, the ground state F Atoms in other magnetic sublevels at level 4 are prepared to the ground state. F =4, m F At the magnetic sublevel where =0; The microwave signal source (1023) is used to generate microwaves with a frequency corresponding to the clock transition frequency and inject them into the microwave cavity (1021). Cesium atoms in the microwave cavity (1021) undergo transitions under the action of microwaves, moving from the ground state. F =4 transitions to the ground state F =3, and under the action of the probe light, the ground state... F Atoms with a value of 3 are excited to the upper energy level. F =2'; The fluorescence collector (1005) is used to detect fluorescence from the upper energy level. F =2' Falls to the ground state F The fluorescent photons generated when =3 are used to obtain the clock transition spectral line signal; The cesium clock locking circuit (1022) is used to lock the frequency of the microwave at the clock transition frequency; The first pump light corresponds to a frequency of 6. 2 S 1 / 2 ( F =3)→6 2 P 3 / 2 ( F’ =4) A laser with a transition frequency and polarization state of π; the second pump light has a frequency corresponding to 6 2 S 1 / 2 ( F =4)→6 2 P 3 / 2 ( F’ =4) A laser with a transition frequency and a polarization state of π; the probe light has a frequency corresponding to 6 2 S 1 / 2 ( F =3)→6 2 P 3 / 2 ( F’ =2) Transition frequency; Or the first pump light corresponds to a frequency of 6. 2 S 1 / 2 ( F =3)→6 2 P 3 / 2 ( F’ =3) A laser with a transition frequency and polarization state of σ polarization, and the second pump light has a frequency corresponding to 6. 2 S 1 / 2 ( F =4)→6 2 P 3 / 2 ( F’ =4) A laser with a transition frequency and a polarization state of π; the probe light has a frequency corresponding to 6 2 S 1 / 2 ( F =3)→6 2 P 3 / 2 ( F’ =2) Transition frequency; Or the first pump light corresponds to a frequency of 6. 2 S 1 / 2 ( F =3)→6 2 P 3 / 2 ( F’ =4) A laser with a transition frequency and polarization state of σ polarization, and the second pump light has a frequency corresponding to 6. 2 S 1 / 2 ( F =4)→6 2 P 3 / 2 ( F’ =4) A laser with a transition frequency and a polarization state of π; the probe light has a frequency corresponding to 6 2 S 1 / 2 ( F =3)→6 2 P 3 / 2 ( F’ =2) Transition frequency.

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