Optical frequency standard device based on cold and hot atom combination system

Abstract

The invention relates to the technical field of atomic frequency standards, in particular to an optical frequency standard device based on a cold and hot atom combination system, and the device is characterized in that emergent laser of a laser enters a laser beam splitter after being modulated by an electro-optical modulator, and is divided into two laser beams; the first laser beam enters the hot atom optical path structure to generate two-photon transition, and generates a first feedback signal through the first modulation-demodulation structure; the second beam of laser enters the cold atom optical path structure to generate two-photon transition, and generates a second feedback signal through the second modulation-demodulation structure; and the first feedback signal and the second feedback signal are synthesized through an adder, and the synthesized feedback signal is fed back to a frequency feedback port of the laser, so that the locking of the laser frequency is realized. According to the invention, the laser provided by one laser is utilized, the advantages of high short-term frequency stability of the hot atom optical frequency standard and good long-term frequency stability of the cold atom optical frequency standard are combined, and the high-performance optical frequency standard with high frequency stability at different time scales can be obtained.

Description

Technical Field

[0001] The present application relates to the technical field of atomic frequency standards, and in particular to an optical frequency standard device based on a cold and hot atom combination system. Background Art

[0002] High-precision time measurement has important applications in navigation and positioning, deep space exploration, communication networks, basic physics, gravitational wave detection, and other fields. Optical atomic clocks based on optical band transitions have an operating frequency (about 10 14 GHz) is about 5 orders of magnitude higher than the microwave frequency (about 109GHz) and has higher frequency stability. It is an important direction for the development of future time-frequency measurement methods.

[0003] The optical frequency standard technology based on two-photon transition has the advantages of high measurement sensitivity, good long-term stability, and high integration. It is a competitive method for realizing miniaturized optical frequency standards.

[0004] From the perspective of atomic temperature, two-photon transition optical frequency standards can be divided into hot atom two-photon optical frequency standards and cold atom two-photon optical frequency standards. Although the former has higher short-term sensitivity, its long-term stability is greatly affected by factors such as collisions between atoms. Although the latter is relatively less affected by collisions between atoms, there is "dead time" in the atomic cooling process, which cannot effectively suppress high-frequency frequency fluctuations. Summary of the invention

[0005] The present application provides an optical frequency standard device based on a hot and cold atom combination system, which effectively combines a hot atom optical frequency standard and a cold atom optical frequency standard together using a set of optical frequency standard devices.

[0006] In order to achieve the above-mentioned purpose, the present application provides an optical frequency standard device based on a combination system of hot and cold atoms, including a laser, an electro-optical modulator, a laser beam splitter, a hot atom optical path structure, a cold atom optical path structure, a first modulation and demodulation structure, a second modulation and demodulation structure and an adder, wherein: the output laser of the laser enters the laser beam splitter after being modulated by the electro-optical modulator and is divided into two laser beams; the first laser beam enters the hot atom optical path structure to undergo a two-photon transition, and generates a first feedback signal through the first modulation and demodulation structure; the second laser beam enters the cold atom optical path structure to undergo a two-photon transition, and generates a second feedback signal through the second modulation and demodulation structure; the first feedback signal and the second feedback signal are synthesized by an adder, and the synthesized feedback signal is fed back to the frequency feedback port of the laser to achieve locking of the laser frequency, thereby obtaining a high-performance optical frequency standard.

[0007] Furthermore, the thermal atom optical path structure includes a first collimator, a first polarization passivator, a first lens, a thermal atom gas chamber, a second lens and a first reflector, wherein: the first laser beam is sequentially expanded and collimated by the first collimator, polarization passivated by the first polarization passivator, focused by the first lens, and the focused laser enters the thermal atom gas chamber; the laser focal position coincides with the center position of the thermal atom gas chamber; the laser emitted from the thermal atom gas chamber is collimated by the second lens and irradiated on the first reflector; the laser reflected by the first reflector returns along the original incident path.

[0008] Furthermore, the first modulation and demodulation structure includes a third lens, a first filter, a first multiplier tube, a first phase-locked amplifier, a first PID feedback circuit and a high-pass filter, wherein: after being irradiated by the first laser beam, the hot atomic gas chamber emits fluorescence; the fluorescence is collected in turn through the third lens, the stray light is filtered out through the first filter, and the signal is converted through the first multiplier tube to convert the fluorescence signal into a first current signal; the first current signal is demodulated by the first phase-locked amplifier to obtain a first error signal; the first error signal enters the first PID feedback circuit to form a first feedback signal; the first feedback signal enters the adder after filtering out the low-frequency signal through the high-pass filter.

[0009] Furthermore, the hot atomic gas chamber includes a first atomic gas chamber, a first magnetic shielding structure and a temperature control device, wherein: the interior of the first atomic gas chamber is filled with hot atoms; the first atomic gas chamber is arranged at the center of the first magnetic shielding structure; the first magnetic shielding structure is arranged inside the temperature control device; a laser light hole is arranged at the center of the front end face and the rear end face of the first magnetic shielding structure and the temperature control device, and a fluorescent light hole is arranged on the side wall thereof.

[0010] Furthermore, the cold atom optical path structure includes a second collimator, a second polarization passivator, a fourth lens, a cold atom gas chamber, a fifth lens and a second reflector, wherein: the second laser beam is sequentially expanded and collimated by the second collimator, polarization passivated by the second polarization passivator, and focused by the fourth lens, and the focused laser enters the cold atom gas chamber; the laser focal position coincides with the center position of the cold atom gas chamber; the laser emitted from the cold atom gas chamber is collimated by the fifth lens and irradiated on the second reflector; the laser reflected by the second reflector returns along the original incident path.

[0011] Furthermore, the second modulation and demodulation structure includes a sixth lens, a second filter, a second multiplier tube, a second phase-locked amplifier, a second PID feedback circuit and a low-pass filter, wherein: after being irradiated by the second laser beam, the cold atomic gas chamber emits fluorescence; the fluorescence is collected in turn through the sixth lens, the stray light is filtered out through the second filter, the signal is converted through the second multiplier tube, and the fluorescence signal is converted into a second current signal; the second current signal is demodulated by the second phase-locked amplifier to obtain a second error signal; the second error signal enters the second PID feedback circuit to form a second feedback signal; the second feedback signal enters the adder after filtering out the high-frequency signal through the low-pass filter.

[0012] Furthermore, the cold atomic gas chamber includes a second atomic gas chamber and a second magnetic shielding structure, wherein: a cold atomic cluster is arranged at the center position inside the second atomic gas chamber; the cold atomic cluster is obtained by means of a magneto-optical trap; the second atomic gas chamber is arranged at the center of the second magnetic shielding structure; a laser light hole is arranged at the center of the front end face and the rear end face of the second magnetic shielding structure, and a fluorescent light hole is arranged on its side wall.

[0013] Furthermore, the second phase-locked amplifier will also output a modulation signal of a fixed frequency, and the modulation signal acts on the electro-optic modulator to achieve modulation of the laser frequency.

[0014] The optical frequency standard device based on the cold and hot atom combination system provided by the present application has the following beneficial effects:

[0015] The present application utilizes laser light provided by a laser to simultaneously interact with hot atoms in a hot atom gas chamber and cold atom clusters in a cold atom gas chamber, thereby combining the advantages of high short-term frequency stability of a hot atom optical frequency standard and good long-term frequency stability of a cold atom optical frequency standard, which is conducive to obtaining a high-performance optical frequency standard with high frequency stability on different time scales. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings constituting a part of this application are used to provide a further understanding of this application, so that other features, purposes and advantages of this application become more obvious. The schematic embodiment drawings and their descriptions of this application are used to explain this application and do not constitute an improper limitation on this application. In the drawings:

[0017] Figure 1 is a schematic diagram of an optical frequency standard device based on a cold and hot atom combination system provided according to an embodiment of the present application;

[0018] Figure 2 is a schematic diagram of a hot atomic gas chamber provided according to an embodiment of the present application;

[0019] Figure 3 is a schematic diagram of a cold atomic gas chamber provided according to an embodiment of the present application;

[0020] Figure 4 It is a schematic diagram of the operation process of the cold atom frequency standard module in the optical frequency standard device based on the cold and hot atom combination system provided in an embodiment of the present application;

[0021] In the figure: 1-laser, 2-electro-optic modulator, 3-laser beam splitter, 41-first collimator, 42-second collimator, 51-first polarization passivator, 52-second polarization passivator, 61-first lens, 62-fourth lens, 71-hot atom gas chamber, 72-cold atom gas chamber, 81-second lens, 82-fifth lens, 91-first reflector, 92-second reflector, 101-third lens, 102-sixth lens, 111-first filter, 112- 2-second optical filter, 121-first multiplier tube, 122-second multiplier tube, 131-first phase-locked amplifier, 132-second phase-locked amplifier, 141-first PID feedback circuit, 142-second PID feedback circuit, 151-high-pass filter, 152-low-pass filter, 16-adder, 171-first atomic gas chamber, 172-second atomic gas chamber, 181-first magnetic shielding structure, 182-second magnetic shielding structure, 191-temperature control device. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0023] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0024] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0025] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to specific circumstances.

[0026] In addition, the term "plurality" shall mean two or more.

[0027] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0028] like Figure 1 As shown, the present application provides an optical frequency standard device based on a hot and cold atom combination system, comprising a laser 1, an electro-optical modulator 2, a laser beam splitter 3, a hot atom optical path structure, a cold atom optical path structure, a first modulation and demodulation structure, a second modulation and demodulation structure and an adder 16, wherein: the outgoing laser of the laser 1 is modulated by the electro-optical modulator 2 and enters the laser beam splitter 3 to be divided into two laser beams; the first laser beam enters the hot atom optical path structure to undergo a two-photon transition, and generates a first feedback signal through the first modulation and demodulation structure; the second laser beam enters the cold atom optical path structure to undergo a two-photon transition, and generates a second feedback signal through the second modulation and demodulation structure; the first feedback signal and the second feedback signal are synthesized by the adder 16, and the synthesized feedback signal is fed back to the frequency feedback port of the laser 1 to achieve locking of the laser frequency, thereby obtaining a high-performance optical frequency standard.

[0029] Specifically, the optical frequency standard device based on the hot and cold atom combination system provided in the embodiment of the present application realizes the hot atom optical frequency standard and the cold atom optical frequency standard in a set of optical frequency standard devices at the same time and performs effective combination. It not only gives full play to the advantage of the high short-term stability of the hot atom two-photon optical frequency standard, but also combines the good long-term stability of the cold atom, thereby finally obtaining a higher frequency stability index.

[0030] More specifically, in the embodiment of the present application, the laser 1 provides a 778nm laser, which is first phase-modulated by the electro-optical modulator 2, and the modulated laser is divided into two parts by a laser beam splitter; wherein, the first laser beam enters the hot atom optical path structure, a two-photon transition occurs, and a first feedback signal is generated by a first modulation and demodulation structure. The low-frequency signal of the first feedback signal may drift over time, affecting the long-term stability of the optical frequency standard, and the low-frequency part of the signal is filtered out by a high-pass filter 151; the second laser beam enters the cold atom optical path structure, a two-photon transition occurs, and a second feedback signal is generated by a second modulation and demodulation structure. The second feedback signal cannot provide a high-frequency error signal, affecting the short-term stability of the optical frequency standard, and the high-frequency part of the signal is filtered out by a low-pass filter 152; the first feedback signal and the second feedback signal after filtering are synthesized by an adder 16, and the synthesized feedback signal is fed back to the frequency feedback port of the laser 1 to achieve laser frequency locking, and finally obtain a high-performance optical frequency standard.

[0031] Furthermore, the thermal atom optical path structure includes a first collimator 41, a first polarization passivator 51, a first lens 61, a thermal atom gas chamber 71, a second lens 81 and a first reflector 91, wherein: the first laser beam is sequentially expanded and collimated by the first collimator 41, polarization passivated by the first polarization passivator 51, and focused by the first lens 61, and the focused laser enters the thermal atom gas chamber 71; the laser focal position coincides with the center position of the thermal atom gas chamber 71; the laser emitted from the thermal atom gas chamber 71 is collimated by the second lens 81 and irradiated on the first reflector 91; the laser reflected by the first reflector 91 returns along the original incident path.

[0032] Furthermore, the first modulation and demodulation structure includes a third lens 101, a first filter 111, a first multiplier tube 121, a first phase-locked amplifier 131, a first PID feedback circuit 141 and a high-pass filter 151, wherein: after being irradiated by the first laser beam, the hot atomic gas chamber 71 emits fluorescence; the fluorescence is collected in turn through the third lens 101, the stray light is filtered out through the first filter 111, and the signal is converted through the first multiplier tube 121 to convert the fluorescence signal into a first current signal; the first current signal is demodulated by the first phase-locked amplifier 131 to obtain a first error signal; the first error signal enters the first PID feedback circuit 141 to form a first feedback signal; the first feedback signal enters the adder 16 after filtering out the low-frequency signal through the high-pass filter 151.

[0033] Further, such as Figure 2As shown, the hot atom gas chamber 71 includes a first atom gas chamber 171, a first magnetic shielding structure 181 and a temperature control device 191, wherein: the first atom gas chamber 171 is filled with hot atoms; the first atom gas chamber 171 is arranged at the center of the first magnetic shielding structure 181; the first magnetic shielding structure 181 is arranged inside the temperature control device 191; laser light holes are arranged at the center of the front and rear faces of the first magnetic shielding structure 181 and the temperature control device 191, and fluorescent light holes are arranged on the side walls. The first magnetic shielding structure 181 is used to shield the influence of the background magnetic field on the stability of the optical frequency standard; the temperature control device 191 is used to heat the temperature of the first atom gas chamber 171 and maintain the temperature in the first atom gas chamber 171 stable; during operation, the temperature of the first atom gas chamber 171 is maintained at about 100°C.

[0034] Furthermore, the cold atom optical path structure includes a second collimator 42, a second polarization passivator 52, a fourth lens 62, a cold atom gas chamber 72, a fifth lens 82 and a second reflector 92, wherein: the second laser beam is sequentially expanded and collimated by the second collimator 42, polarization passivated by the second polarization passivator 52, focused by the fourth lens 62, and the focused laser enters the cold atom gas chamber 72; the laser focal position coincides with the center position of the cold atom gas chamber 72; the laser emitted from the cold atom gas chamber 72 is collimated by the fifth lens 82 and irradiated on the second reflector 92; the laser reflected by the second reflector 92 returns along the original incident path.

[0035] Furthermore, the second modulation and demodulation structure includes a sixth lens 102, a second filter 112, a second multiplier tube 122, a second phase-locked amplifier 132, a second PID feedback circuit 142 and a low-pass filter 152, wherein: after being irradiated by the second laser beam, the cold atomic gas chamber 72 emits fluorescence; the fluorescence is collected in turn through the sixth lens 102, stray light is filtered out through the second filter 112, and signal conversion is performed through the second multiplier tube 122 to convert the fluorescence signal into a second current signal; the second current signal is demodulated by the second phase-locked amplifier 132 to obtain a second error signal; the second error signal enters the second PID feedback circuit 142 to form a second feedback signal; the second feedback signal enters the adder 16 after filtering out the high-frequency signal through the low-pass filter 152.

[0036] Further, such as Figure 3 As shown, the cold atomic gas chamber 72 includes a second atomic gas chamber 172 and a second magnetic shielding structure 182, wherein: a cold atomic group is arranged at the center of the second atomic gas chamber 172; the cold atomic group is obtained by a magneto-optical trap, the atomic temperature is less than 100 microkelvin, and the number of atoms is greater than 10 5; The second atomic gas cell 172 is disposed at the center of the second magnetic shielding structure 182; laser light passing holes are provided at the centers of the front end face and the rear end face of the second magnetic shielding structure 182, and fluorescence light passing holes are provided on its side wall. The second magnetic shielding structure 182 is used to shield the influence of the background magnetic field on the stability of the optical frequency standard. After shielding, the magnitude of the background magnetic field in the environment where the second atomic gas cell 172 is located is usually about mGs.

[0037] Furthermore, the second lock-in amplifier 132 also outputs a modulation signal with a fixed frequency, and this modulation signal acts on the electro-optic modulator 2 to achieve modulation of the laser frequency.

[0038] Specifically, taking 87 Rb atoms as an example, the working process of the optical frequency standard device based on the cold and hot atom combined system provided by the embodiments of the present application will be introduced in more detail:

[0039] The laser 1 provides the laser necessary for two-photon transition of atoms. The laser frequency is near the resonance frequency of the atomic |5 2 S 12 , F = 2 to |5 2 D 52 , F¢ = 4> transition, about 385.284 THz, and the laser power is about 50 mW; the electro-optic modulator 2 is connected to the laser 1 through an optical fiber and is used to modulate the laser emitted by the laser 1. This modulation signal is from the second lock-in amplifier 132, the modulation frequency is 100 kHz, and the modulation signal amplitude is 1 V; the modulated laser is transmitted through the optical fiber to the laser beam splitter 3, and the laser beam splitter 3 divides the laser into two parts, and the powers are about 25 mW respectively;

[0040] The first beam of laser is transmitted through the optical fiber to the first laser collimator to expand and collimate the laser. The spot diameter of the laser is about 1 mm; the first polarization purifier purifies the polarization of the collimated laser to achieve a high laser extinction ratio; the first beam of laser is focused by the first lens 61. The focal length of the first lens 61 is 100 mm, and the laser focus position coincides with the center position of the hot atomic gas cell 71; the laser is then collimated by the second lens 81 (the focal length is also 100 mm) and reflected by the first mirror 91; the first mirror 91 has the function of adjusting the two-dimensional direction of the laser, and by adjusting the first mirror 91, the laser can be made to return along the original incident path;

[0041] The atoms in the hot atomic gas cell 71 are under the action of the forward laser and the reflected laser of the first beam of laser. The atoms simultaneously absorb the photons in the two beams of laser and complete the transition from the ground state |5 2 S 12 , F = 2 to the excited state 5 2 D 52 ​,F￠=4>; then the atom transitions from |5 2 D 52 >state spontaneously radiates to |6 2 P 32 > state, then from |6 2 P 32 The spontaneous radiation of the state reaches |5 2 S 12 > state, and emits 420nm fluorescence;

[0042] The third lens 101 (with a focal length of 50 mm) is used to collect the fluorescence emitted by the atoms in the hot atomic gas chamber 71. The first filter 111 has a light transmission center wavelength of 420 nm and is used to filter out stray light in the fluorescence. The fluorescence signal is converted into a first current signal through the first multiplier tube 121.

[0043] The first phase-locked amplifier 131 demodulates the first current signal, and the demodulated signal is consistent with the modulation signal of the electro-optical modulator 2 at 100kHz. The first error signal can be obtained by changing the phase of the demodulated signal, and the first feedback signal is obtained through the first PID feedback circuit 141; the first feedback signal is the feedback signal of the thermal atomic frequency standard part.

[0044] The second laser beam is transmitted to the second laser collimator through the optical fiber to expand and collimate the laser beam, and the laser spot diameter is about 1mm; the second polarization purifier purifies the polarization of the collimated laser beam to achieve a higher laser extinction ratio; the second laser beam is focused by the fourth lens 62, the focal length of the fourth lens 62 is 100mm, and the laser focal position coincides with the center position of the cold atomic gas chamber 72; the laser beam is then collimated by the fifth lens 82 (the focal length is also 100mm), and the laser beam is reflected by the second reflector 92; the second reflector 92 has the function of adjusting the two-dimensional direction of the laser beam, and the laser beam can be returned along the original incident path by adjusting the second reflector 92;

[0045] The cold atom group in the cold atom gas chamber 72 undergoes transition under the action of the forward laser and the reflected laser of the second laser beam, and its energy level change is the same as the change of the hot atom energy level in the hot atom gas chamber 71, which will not be described in detail.

[0046] The sixth lens 102 (with a focal length of 50 mm) is used to collect the fluorescence emitted by the atoms in the cold atom gas chamber 72. The second filter 112 has a light transmission center wavelength of 420 nm and is used to filter out stray light in the fluorescence. The fluorescence signal is converted into a second current signal through the second multiplier tube 122.

[0047] The second lock-in amplifier 132 demodulates the second current signal. The demodulated signal is consistent with the modulation signal of the electro-optical modulator 2 at 100kHz. The second error signal can be obtained by changing the phase of the demodulated signal, and the second feedback signal is obtained through the second PID feedback circuit 142. The second feedback signal is the feedback signal of the cold atomic frequency standard part.

[0048] The high-pass filter 151 filters out the low-frequency signal in the first feedback signal, and the low-pass filter 152 filters out the high-frequency signal in the second feedback signal. The filtered signals are added by the adder 16 and then fed back to the frequency feedback port of the laser 1 to lock the laser frequency and ultimately realize a high-performance optical frequency standard with both high short-term stability and high long-term stability.

[0049] More specifically, the hot atom frequency standard part works continuously during the measurement process, and the first feedback signal generated by the first PID feedback circuit 141 is always fed back to the laser 1; while the cold atom frequency standard part needs time t to prepare cold atoms during operation, and within the time period t′ of generating the optical frequency standard signal, the cold atom preparation process ends and the second feedback signal generated by the second PID feedback circuit 142 is fed back to the laser 1. Figure 4 As shown, the start time of measurement of the optical frequency standard device of the cold and hot atom combination system is recorded as t 0 , then at t 0 ~t 0 +t time period, the cold atom preparation process starts, the first PID feedback circuit 141 is turned on, and the second PID feedback circuit 142 is turned off, then at t 0 +t~t 0 During the time period of +t+t′, the cold atom preparation process is turned off, the first PID feedback circuit 141 is turned on, and the second PID feedback circuit 142 is turned on; then the above process is repeated, that is, at t 0 +t+t′~t 0 In the time period of +2t+t′, the cold atom preparation process starts, the first PID feedback circuit 141 is turned on, and the second PID feedback circuit 142 is turned off; at t 0 +2t+t′~t 0 During the time period of +2t+2t′, the cold atom preparation process is turned off, the first PID feedback circuit 141 is turned on, and the second PID feedback circuit 142 is turned on.

[0050] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An optical frequency standard device based on a cold and hot atom combination system, characterized in that: The invention comprises a laser, an electro-optic modulator, a laser beam splitter, a hot atom optical path structure, a cold atom optical path structure, a first modulation and demodulation structure, a second modulation and demodulation structure and an adder, wherein: The outgoing laser of the laser enters the laser beam splitter after being modulated by the electro-optic modulator and is divided into two laser beams; A first laser beam enters the hot atom optical path structure to generate a two-photon transition, and generates a first feedback signal through the first modulation and demodulation structure; The second laser beam enters the cold atom optical path structure to generate a two-photon transition, and generates a second feedback signal through the second modulation and demodulation structure; The first feedback signal and the second feedback signal are synthesized by the adder, and the synthesized feedback signal is fed back to the frequency feedback port of the laser to achieve locking of the laser frequency, thereby obtaining a high-performance optical frequency standard.

2. The optical frequency standard device based on the cold and hot atom combination system according to claim 1 is characterized in that: The thermal atom optical path structure comprises a first collimator, a first polarization passivator, a first lens, a thermal atom gas chamber, a second lens and a first reflector, wherein: The first laser beam is sequentially expanded and collimated by the first collimator, polarization-passivated by the first polarization passivator, and focused by the first lens, and the focused laser beam enters the hot atomic gas chamber; The laser focus position coincides with the center position of the hot atom gas chamber; The laser emitted from the hot atom gas cell is collimated by the second lens and irradiated onto the first reflector; The laser light reflected by the first reflector returns along the original incident path.

3. The optical frequency standard device based on the cold and hot atom combination system according to claim 2 is characterized in that: The first modulation and demodulation structure includes a third lens, a first filter, a first multiplier tube, a first lock-in amplifier, a first PID feedback circuit and a high-pass filter, wherein: After being irradiated by the first laser beam, the hot atomic gas cell emits fluorescence; The fluorescence is collected in sequence through the third lens, the stray light is filtered out through the first filter, and the signal is converted through the first multiplier tube to convert the fluorescence signal into a first current signal; The first current signal is demodulated by the first lock-in amplifier to obtain a first error signal; The first error signal enters the first PID feedback circuit to form a first feedback signal; The first feedback signal enters the adder after the low-frequency signal is filtered out by the high-pass filter.

4. The optical frequency standard device based on the cold and hot atom combination system according to claim 3 is characterized in that: The hot atomic gas chamber comprises a first atomic gas chamber, a first magnetic shielding structure and a temperature control device, wherein: The first atomic gas chamber is filled with hot atoms; The first atomic gas chamber is disposed at the center of the first magnetic shielding structure; The first magnetic shielding structure is disposed inside the temperature control device; Laser light holes are arranged at the centers of the front and rear faces of the first magnetic shielding structure and the temperature control device, and fluorescent light holes are arranged on the side walls thereof.

5. The optical frequency standard device based on the cold and hot atom combination system according to claim 4 is characterized in that: The cold atom optical path structure includes a second collimator, a second polarization passivator, a fourth lens, a cold atom gas chamber, a fifth lens and a second reflector, wherein: The second laser beam is sequentially expanded and collimated by the second collimator, polarization-passivated by the second polarization passivator, and focused by the fourth lens, and the focused laser beam enters the cold atom gas chamber; The laser focus position coincides with the center position of the cold atom gas chamber; The laser emitted from the cold atomic gas cell is collimated by the fifth lens and irradiated onto the second reflector; The laser light reflected by the second reflector returns along the original incident path.

6. The optical frequency standard device based on the cold and hot atom combination system according to claim 5, characterized in that: The second modulation and demodulation structure includes a sixth lens, a second filter, a second multiplier tube, a second lock-in amplifier, a second PID feedback circuit and a low-pass filter, wherein: After being irradiated by the second laser beam, the cold atomic gas cell emits fluorescence; The fluorescence is collected in sequence through the sixth lens, the stray light is filtered out through the second filter, and the signal is converted through the second multiplier tube to convert the fluorescence signal into a second current signal; The second current signal is demodulated by the second lock-in amplifier to obtain a second error signal; The second error signal enters the second PID feedback circuit to form a second feedback signal; The second feedback signal enters the adder after the high-frequency signal is filtered out by the low-pass filter.

7. The optical frequency standard device based on the cold and hot atom combination system according to claim 6 is characterized in that: The cold atomic gas chamber comprises a second atomic gas chamber and a second magnetic shielding structure, wherein: A cold atomic group is arranged at the center of the second atomic gas chamber; Cold atomic clusters are obtained by means of magneto-optical traps; The second atomic gas chamber is disposed at the center of the second magnetic shielding structure; Laser light-through holes are arranged at the centers of the front and rear surfaces of the second magnetic shielding structure, and fluorescent light-through holes are arranged on the side walls thereof.

8. The optical frequency standard device based on the cold and hot atom combination system according to claim 7, characterized in that: The second lock-in amplifier also outputs a modulation signal of a fixed frequency, and the modulation signal acts on the electro-optical modulator to modulate the laser frequency.

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