Chip Faraday active optical clock and implementation method thereof

Abstract

The invention discloses a chip Faraday active optical clock and an implementation method thereof. The device comprises a semiconductor laser diode, a substrate wafer and a cover plate wafer, a cavity wafer is arranged on the substrate wafer, a first polarization splitting prism, a second polarization splitting prism, an MEMS alkali metal atom gas chamber and an active optical clock resonant cavity mirror are arranged in the cavity wafer, and the cavity wafer and the cover plate wafer are connected to form a closed cavity; a wide-spectrum fluorescence signal output by the semiconductor laser diode is transmitted and input into the first polarization splitting prism through the substrate wafer to be divided into two beams, and one beam enters the atomic gas chamber for frequency locking; the second polarization splitting prism divides the laser output by the atomic gas chamber into two beams, one beam is output as a chip Faraday active optical clock laser, and the other beam enters an active optical clock resonant cavity mirror; the active optical clock resonant cavity mirror reflects a part of the incident laser back to the diode to realize continuous oscillation of the laser; wherein the chip Faraday active optical clock works in a bad cavity area.

Description

Technical Field

[0001] The present invention belongs to the technical field of atomic clocks and quantum frequency standards, and in particular relates to a chip-based Faraday active optical clock and a method for realizing the same. Background Art

[0002] Active optical clocks, a high-potential laser source or quantum frequency standard that stores coherence in atomic dipoles rather than traditional resonant cavities, have considerable research potential in cavity quantum electrodynamics, new atomic clocks, laser physics, quantum manipulation, etc. With the rise of the concept of active optical clocks, superradiant active optical clock lasers implemented using hot atomic gas chambers, hot atomic beams, mobile magneto-optical traps, mobile optical lattices, etc. have demonstrated their principle advantages, and have been widely verified in theory and experiment in terms of surpassing the Schloss-Townes quantum linewidth limit. However, the active optical clocks implemented by the above methods require complex steps to obtain pump sources and atomic systems. For the cold atom scheme, multiple laser systems are required to complete atomic laser cooling and trapping, and it is difficult to achieve continuous output. For the ultra-narrow linewidth quantum transition scheme, a high-precision resonant cavity is required to achieve optical feedback, which increases the system complexity and resistance to environmental interference. Therefore, active optical clocks need further breakthroughs in terms of practicality, miniaturization, and continuous operation. How to practicalize active optical clocks, which have extremely high potential in terms of linewidth and frequency stability and are expected to become the next generation of new optical clocks, is an urgent problem to be solved.

[0003] In summary, the core issue of the present invention is to find new methods to solve the problems of active optical clocks in terms of practicality, miniaturization, and continuous operation, and to improve the performance of existing passive atomic clocks and expand their scope of application. Summary of the invention

[0004] In order to solve the above problems, the purpose of the present invention is to provide a chip-based Faraday active optical clock and its implementation method. The present invention adopts a chip-based Faraday active optical clock implementation scheme, which can combine high-gain semiconductor media and a micro-atomic filter based on a MEMS atomic gas chamber to achieve bad cavity laser oscillation in an on-chip integrated size, and the gain bandwidth is limited to the atomic Doppler broadening line, that is, equal to the atomic filter transmission spectrum bandwidth. The chip-based structure and specific cavity mirror design can significantly increase the cavity attenuation rate, that is, the cavity mode line width, so that the chip-based Faraday active optical clock works in the bad cavity area, giving full play to the narrow line width and cavity pulling suppression advantages of the active optical clock.

[0005] The present invention can realize a chip-level Faraday active optical clock with a line width far less than the Schawlow-Townes quantum limit line width of a good cavity Faraday laser. By adjusting the atomic number density of the MEMS atomic filter to change the transmission spectrum, it is equivalent to directly adjusting the gain attenuation rate Γ, thereby changing the bad cavity coefficient. By studying the relationship between the cavity pulling suppression coefficient and the ratio of κ and Γ, theoretical analysis and experimental verification of the modified Schawlow-Townes quantum limit line width changes under different cavity pulling suppression levels, the optimal parameters are found to explore the experimentally achievable Faraday active optical clock limit line width. Active optical clocks are an important direction for the future development of atomic clocks and an effective way to achieve sub-natural line width superradiant lasers. The chip-level Faraday active optical clock proposed by the present invention is an important solution to the difficulties of practical, miniaturized, and continuous operation of active optical clocks.

[0006] This solution has four innovations and advantages: ① The gain is separated from the frequency-selective device to reduce the interference of frequency selection on the gain, and the semiconductor gain is large, which makes it easier to achieve laser oscillation; ② By adjusting the temperature to adjust the transmission spectrum bandwidth of the frequency-selective device, the ratio of the gain bandwidth to the cavity mode bandwidth can be continuously adjusted, thereby continuously adjusting the bad cavity coefficient; ③ MEMS integration achieves a smaller volume, which can not only improve the cavity attenuation rate, so that the laser works in the bad cavity area, but also greatly improve the practicality of the system; ④ By adjusting the bad cavity coefficient, the cavity attenuation rate is adjusted to achieve the purpose of adjusting the laser line width. Among them, the bad cavity coefficient = cavity mode line width ÷ gain line width. When the cavity length of the MEMS integrated Faraday laser is determined, that is, the cavity mode line width is determined, then the bad cavity coefficient can be changed by changing the gas chamber temperature to change the gain line width. Different bad cavity coefficients have different cavity pulling suppression effects.

[0007] One object of the present invention is to propose a chip-based Faraday active optical clock, which includes: a semiconductor laser diode, a first polarization splitter prism, a MEMS alkali metal atom gas chamber, a second polarization splitter prism, a first permanent magnet, a second permanent magnet, an active optical clock resonant cavity mirror, a base wafer, a cavity wafer, a cover wafer, a first solder sheet, a second solder sheet, and a getter.

[0008] Among them, the semiconductor laser diode is used as the gain medium of the chip-based Faraday active optical clock, outputting a wide-spectrum fluorescence signal, and the central wavelength is related to the type of atomic transition of the atomic filter, including but not limited to 767nm, 770nm, 780nm, 795nm, 852nm, and 894nm, corresponding to the D2 and D1 transition lines of potassium atoms, rubidium atoms, and cesium atoms, respectively. The quantum well materials of different wavelengths are different, such as GaAs and InGaAs; the semiconductor laser diode is a FP cavity structure, with high reflection on the rear cavity surface and high transmission on the front cavity surface, in order to prevent the generation of intracavity mode;

[0009] The polarization directions of the first polarization beam splitter prism and the second polarization beam splitter prism are perpendicular; the material is K9 glass (optical borosilicate glass);

[0010] The MEMS alkali metal atomic gas cell selects the frequency of the incident fluorescence signal, enabling the transmission output of the above-wavelength laser. The MEMS alkali metal atomic gas cell can be filled with potassium atoms, rubidium atoms, and cesium atoms. Each light-passing hole surface is plated with metal and connected to 4 electrode pins, achieving the effects of heating the gas cell to increase the atomic number density and controlling the temperature. To achieve a better frequency selection bandwidth and transmittance, the gas cell generally needs to be heated to 100 °C; the material is selected as borosilicate glass or silicon, which has high transmittance for light with wavelengths of 767 nm, 770 nm, 780 nm, 795 nm, 852 nm, and 894 nm, corresponding to the D2 and D1 transition lines of potassium atoms, rubidium atoms, and cesium atoms;

[0011] The first permanent magnet and the second permanent magnet are used to generate a uniform magnetic field along the light propagation direction of the gas cell;

[0012] The first polarization beam splitter prism, the second polarization beam splitter prism, the MEMS alkali metal atomic gas cell, the first permanent magnet, and the second permanent magnet together form a Faraday atomic filter, achieving the frequency selection and filtering effect on the broadband fluorescence signal. At the same time, the transmission bandwidth of this Faraday atomic filter directly determines the gain attenuation rate Γ, and the attenuation rate is generally 2π×1 GHz; only the light with the transition frequency near the atomic resonance frequency can achieve the rotation of the polarization direction and be output from the second polarization beam splitter prism;

[0013] The cavity mirror of the active optical clock resonator is used to achieve optical feedback. The reflectivity of this mirror does not need to be very high, thereby increasing the cavity attenuation rate κ. Among them, the mirror reflectivity and the transmittance of the Faraday atomic filter jointly determine κ. By changing the parameters of the Faraday atomic filter and the mirror reflectivity, make κ > Γ, and the laser operates in the bad cavity region; the material is selected as ULE glass (zero-expansion glass, titanium dioxide-silicate glass). In addition to plane mirrors, it can also be made into a corner cube array, and the material is K9 optical glass, thereby enhancing the mechanical robustness of the laser;

[0014] The substrate wafer material is silicon, which is the basic material of semiconductor chips, bears and connects electronic components, is the template for etching and lithography, and provides heat dissipation and mechanical support;

[0015] The cavity wafer material is glass, silicon dioxide, which is the basic material for semiconductor chip manufacturing, provides a physical carrier for chip manufacturing, and can etch out tiny circuit structures;

[0016] The cover wafer material is silicon, which is the basic material of semiconductor chips, bears and connects electronic components, is the template for etching and lithography, and provides heat dissipation and mechanical support;

[0017] The first solder sheet is used to connect the substrate wafer and the cavity wafer;

[0018] The second solder sheet is used to connect the cover wafer and the cavity wafer;

[0019] Getters are used to absorb gases and maintain a vacuum environment;

[0020] Finally, the Faraday active optical clock laser output is achieved under the weak feedback of the active optical clock resonant cavity mirror.

[0021] Another object of the present invention is to provide a method for realizing a chip-based Faraday active optical clock, comprising the following steps:

[0022] 1) The fluorescence output by the semiconductor laser diode is linearly polarized light, which is collimated and transmitted through the substrate wafer to the first polarization beam splitter prism;

[0023] 2) The linearly polarized light is reflected by the first polarization beam splitter prism, and the s light is reflected into the MEMS alkali metal atom gas chamber;

[0024] 3) The polarization direction of the linearly polarized light passing through the MEMS alkali metal atom gas cell will rotate due to the Faraday magneto-optical rotation effect. By designing the length of the atomic gas cell, the gas cell temperature, and the magnetic field strength of the permanent magnet, the polarization direction of the linearly polarized light can be rotated by 90°;

[0025] 4) The linearly polarized light rotated by 90° can pass through the second polarization beam splitter prism whose polarization direction is perpendicular to that of the first polarization beam splitter prism;

[0026] 5) The linearly polarized light output from the second polarization beam splitter prism is incident on the active optical clock resonant cavity mirror, and laser oscillation is realized under the weak feedback of the active optical clock resonant cavity mirror. The Faraday active optical clock laser is reflected and output from the second polarization beam splitter prism and used as a narrow linewidth laser source or a high-performance optical frequency standard, which is applied to the field of quantum precision measurement.

[0027] Advantages of the present invention:

[0028] The present invention proposes for the first time a chip-based Faraday active optical clock, wherein: ① the gain is separated from the frequency selection device to reduce the interference of the frequency selection on the gain, and the semiconductor gain is relatively large, making it easier to achieve laser oscillation; ② the transmission spectrum bandwidth of the frequency selection device is adjusted by adjusting the temperature, and the ratio of the gain bandwidth to the cavity mode bandwidth can be continuously adjusted, thereby continuously adjusting the bad cavity coefficient; ③ the present invention proposes for the first time a scheme to achieve cavity length compression through a MEMS integration scheme, thereby increasing the bad cavity coefficient, and a smaller volume can be achieved through MEMS integration, which can not only increase the cavity attenuation rate and enable the laser to work in the bad cavity area, but also greatly improve the practicality of the system; ④ by adjusting the bad cavity coefficient, the cavity attenuation rate is adjusted to achieve the purpose of adjusting the laser line width.

[0029] By verifying the changes in laser line width under good cavity, bad cavity, and close conditions of good and bad cavity, and verifying the outstanding contribution of cavity pulling suppression effect introduced by bad cavity to laser line width narrowing, a continuous active optical clock superradiant laser source with minimum line width can be realized. The laser line width is 100Hz, which is much smaller than the gain attenuation rate, and the transmission spectrum gain bandwidth is 1GHz, that is, the gain attenuation rate is 10nm=10000pm=4000GHz, which can achieve a laser line width much smaller than the gain attenuation rate of 4×10 10 Times the chip's active optical clock. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of a first embodiment of a chip-based Faraday active optical clock according to the present invention.

[0031] Explanation of the accompanying drawings: 1-semiconductor laser diode, 2-first polarization splitter prism, 3-MEMS alkali metal atom gas chamber, 4-second polarization splitter prism, 5-first permanent magnet, 6-second permanent magnet, 7-active optical clock resonant cavity mirror, 8-substrate wafer, 9-cavity wafer, 10-cover wafer, 11-first solder sheet, 12-second solder sheet, 13-getter. DETAILED DESCRIPTION

[0032] The present invention will be further described below through specific embodiments in conjunction with the accompanying drawings.

[0033] Embodiment 1

[0034] like Figure 1 As shown, a chip-based Faraday active optical clock of this embodiment includes: a semiconductor laser diode 1, a first polarization splitter prism 2, a MEMS alkali metal atom gas chamber 3, a second polarization splitter prism 4, a first permanent magnet 5, a second permanent magnet 6, an active optical clock resonant cavity mirror 7, a base wafer 8, a cavity wafer 9, a cover wafer 10, a first solder sheet 11, a second solder sheet 12, and a getter 13.

[0035] Among them, the semiconductor laser diode 1 is used as the gain medium of the chip-based Faraday active optical clock to output a fluorescence signal, and the central wavelength is related to the type of atomic transition of the atomic filter, including but not limited to 767nm, 770nm, 780nm, 795nm, 852nm, and 894nm, which correspond to the D2 and D1 transition lines of potassium atoms, rubidium atoms, and cesium atoms, respectively. The quantum well materials of different wavelengths are different, such as GaAs and InGaAs; the semiconductor laser diode 1 is a FP cavity structure, with a high reflection on the rear cavity surface and a high transmission on the front cavity surface, in order to prevent the generation of an intracavity mode;

[0036] The polarization directions of the first polarization beam splitter prism 2 and the second polarization beam splitter prism 4 are perpendicular; the material is K9 glass (optical borosilicate glass);

[0037] The MEMS alkali metal atom gas chamber 3 can be filled with potassium atoms, rubidium atoms, and potassium atoms. Each light-through hole surface is plated with metal and connected to 4 electrode pins to achieve the effect of heating the gas chamber to increase the atomic number density and temperature control. In order to achieve a better frequency selection bandwidth and transmittance, the gas chamber generally needs to be heated to 100°C; the material is high borosilicate glass or silicon;

[0038] The first permanent magnet 5 and the second permanent magnet 6 are used to generate a uniform magnetic field along the light propagation direction of the air chamber;

[0039] The first polarization beam splitter prism 2, the second polarization beam splitter prism 4, the MEMS alkali metal atom gas chamber 3, the first permanent magnet 5 and the second permanent magnet 6 together form a Faraday atomic filter, which realizes the frequency-selective filtering effect on the wide-spectrum fluorescence signal. At the same time, the transmission bandwidth of the Faraday atomic filter directly determines the gain attenuation rate Γ, and the attenuation rate is generally 2π×1GHz; only the light with a transition frequency near the atomic resonance frequency can realize the polarization direction rotation and be output from the second polarization beam splitter prism 4;

[0040] The active optical clock resonant cavity mirror 7 is used to realize optical feedback. The reflectivity of the cavity mirror does not need to be very high, thereby increasing the cavity attenuation rate κ, wherein the cavity mirror reflectivity and the transmittance of the Faraday atomic filter jointly determine κ. The Faraday atomic filter and cavity mirror reflectivity parameters are changed to make κ>Γ, and the laser works in the bad cavity area; the material selected is ULE glass (zero expansion glass, titanium dioxide-silicate glass). In addition to the plane mirror, it can also be made into a pyramid array, and the material is K9 optical glass, thereby enhancing the mechanical robustness of the laser;

[0041] The base wafer 8 serves as a supporting structure for the entire chip, providing mechanical stability and thermal stability; the base wafer is usually made of a material with high thermal conductivity and low expansion coefficient to ensure stable operation of the chip in different environments.

[0042] The cavity wafer 9, the substrate wafer 8 and the cover wafer 10 together form a closed chamber; the interior of the cavity wafer 9 can be filled with a specific gas or a vacuum environment to optimize the optical performance.

[0043] The cover wafer 10 is used to seal the cavity and protect the internal components from external pollution and mechanical damage; the cover wafer 10 usually has high transparency to ensure smooth transmission of optical signals;

[0044] The first solder sheet 11 is used to connect the base wafer 8 and the cavity wafer 9; the melting point and material properties of the solder sheet need to match those of the base and the cavity wafer to ensure the reliability and stability of the connection.

[0045] The second solder sheet 12 is used to connect the cover wafer 10 and the cavity wafer 9;

[0046] The getter 13 is used to absorb the gas in the closed chamber and maintain the vacuum environment of the closed chamber, thereby improving the performance and life of the optical element and reducing the interference of the gas on the optical signal;

[0047] Finally, under the optical weak feedback of the active optical clock resonant cavity mirror 7, the Faraday active optical clock laser output is realized.

[0048] A method for implementing a chip-based Faraday active optical clock in this embodiment includes the following steps:

[0049] 1) The fluorescence output by the semiconductor laser diode 1 is linearly polarized light, which is collimated and transmitted through the base wafer 8 to the first polarization beam splitter prism 2;

[0050] 2) The linearly polarized light is reflected by the first polarization beam splitter prism 2, and the s-light is reflected into the MEMS alkali metal atom gas chamber 3;

[0051] 3) The polarization direction of the linearly polarized light passing through the MEMS alkali metal atom gas cell 3 will rotate due to the Faraday magneto-optical rotation effect. By designing the length of the atomic gas cell, the gas cell temperature, and the magnetic field strength of the permanent magnet, the polarization direction of the linearly polarized light can be rotated by 90°;

[0052] 4) The linearly polarized light rotated by 90° can pass through the second polarization beam splitter prism 4 whose polarization direction is perpendicular to the first polarization beam splitter prism 2;

[0053] 5) The linearly polarized light output from the second polarization beam splitter prism 4 is incident on the active optical clock resonant cavity mirror 7, and laser oscillation is realized under the weak feedback of the active optical clock resonant cavity mirror. The Faraday active optical clock laser is reflected and output from the second polarization beam splitter prism 4 and used as a narrow linewidth laser source or a high-performance optical frequency standard, which is applied to the field of quantum precision measurement.

[0054] Finally, it should be noted that the purpose of publishing the embodiments is to help further understand the present invention, but those skilled in the art can understand that various substitutions and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the present invention should not be limited to the contents disclosed in the embodiments, and the scope of protection claimed by the present invention shall be subject to the scope defined in the claims.

Claims

1. A chip-based Faraday active optical clock, characterized in that: The invention comprises a semiconductor laser diode (1), a base wafer (8), and a cover wafer (10); a cavity wafer (9) is arranged on the base wafer (8); a first polarization beam splitter prism (2), a second polarization beam splitter prism (4), a MEMS alkali metal atom gas chamber (3), and an active optical clock resonant cavity mirror (7) are arranged in the cavity wafer (9); the cavity wafer (9) and the cover wafer (10) are connected to form a closed cavity; the polarization directions of the first polarization beam splitter prism (2) and the second polarization beam splitter prism (4) are perpendicular; The semiconductor laser diode (1) is used as a gain medium to output a wide-spectrum fluorescence signal which is transmitted through the base wafer (8) and input into the first polarization beam splitter prism (2); The first polarization beam splitter (2) is used to split the wide-spectrum fluorescence signal into two light beams with different polarization directions, one of which enters the MEMS alkali metal atom gas chamber (3) for frequency locking; The MEMS alkali metal atom gas chamber (3) is used to select the frequency of the incident fluorescent signal so that the target wavelength laser is transmitted and output; The second polarization beam splitter (4) is used to split the target wavelength laser output by the MEMS alkali metal atom gas chamber (3) into two beams, one beam being output as a chip-based Faraday active optical clock laser through the substrate wafer (8) and the other beam being incident on the active optical clock resonant cavity mirror (7); The active optical clock resonant cavity mirror (7) is used to reflect a portion of the incident laser light back to the semiconductor laser diode (1), so as to achieve continuous oscillation and frequency stabilization of the laser light between the semiconductor laser diode (1) and the active optical clock resonant cavity mirror (7); The cavity attenuation rate κ is determined by adjusting the reflectivity of the active optical clock resonant cavity mirror (7) and the transmittance of the MEMS alkali metal atom gas chamber (3), and the gain attenuation rate Γ is changed by adjusting the transmission bandwidth of the MEMS alkali metal atom gas chamber (3) so that κ>Γ, thereby making the laser work in the bad cavity area.

2. The chip-based Faraday active optical clock according to claim 1, characterized in that: The invention also comprises a first permanent magnet (5) and a second permanent magnet (6), wherein the first permanent magnet (5) and the second permanent magnet (6) are used to generate a uniform magnetic field along the light propagation direction in the MEMS alkali metal atom gas chamber (3); the first polarization beam splitter prism (2), the second polarization beam splitter prism (4), the MEMS alkali metal atom gas chamber (3), the first permanent magnet (5) and the second permanent magnet (6) constitute a Faraday atomic filter.

3. The chip-based Faraday active optical clock according to claim 1 or 2, characterized in that: Each light-through hole surface of the MEMS alkali metal atom gas chamber (3) is plated with metal and connected with a plurality of electrode pins, which are used to heat the plated metal to increase the atomic number density and control the temperature of the MEMS alkali metal atom gas chamber (3); the material of the light-through hole surface is high borosilicate glass or silicon.

4. The chip-based Faraday active optical clock according to claim 1, characterized in that: The transmission spectrum of the MEMS alkali metal atom gas chamber (3) is changed by adjusting the atomic number density filled in the MEMS alkali metal atom gas chamber (3), thereby adjusting the gain attenuation rate Γ.

5. The chip-based Faraday active optical clock according to claim 1, characterized in that: It also includes a getter (13), which is used to absorb the gas in the closed cavity to maintain the vacuum environment of the closed cavity.

6. The chip-based Faraday active optical clock according to claim 1, characterized in that: The base wafer (8) is connected to the cavity wafer (9) via a first solder sheet (11); and the cover wafer (10) is connected to the cavity wafer via a second solder sheet (12).

7. The chip-based Faraday active optical clock according to claim 1, characterized in that: The material of the first polarization beam splitter prism (2) and the second polarization beam splitter prism (4) is K9 glass.

8. The chip-based Faraday active optical clock according to claim 1, characterized in that: The atoms filled in the MEMS alkali metal atom gas chamber (3) are potassium atoms, and the central wavelength of the wide-spectrum fluorescence signal corresponds to the D2 and D1 transition lines of the potassium atoms; the atoms filled in the MEMS alkali metal atom gas chamber (3) are rubidium atoms, and the central wavelength of the wide-spectrum fluorescence signal corresponds to the D2 and D1 transition lines of the rubidium atoms; or the atoms filled in the MEMS alkali metal atom gas chamber (3) are cesium atoms, and the central wavelength of the wide-spectrum fluorescence signal corresponds to the D2 and D1 transition lines of the cesium atoms.

9. A method for realizing a chip-based Faraday active optical clock, the steps comprising: 1) A cavity wafer (9) is arranged on a base wafer (8), a first polarization beam splitter prism (2), a second polarization beam splitter prism (4), a MEMS alkali metal atom gas chamber (3), and an active optical clock resonant cavity mirror (7) are arranged in the cavity wafer (9), and the cavity wafer (9) is connected to a cover wafer (10) to form a closed cavity; the polarization directions of the first polarization beam splitter prism (2) and the second polarization beam splitter prism (4) are perpendicular; 2) using a semiconductor laser diode (1) to output a linearly polarized wide-spectrum fluorescence signal, which is collimated and transmitted through a base wafer (8) to be incident on a first polarization beam splitting prism (2); 3) The first polarization beam splitter (2) splits the incident light beam into two light beams with different polarization directions, and reflects one of the light beams into the MEMS alkali metal atom gas chamber (3); 4) The MEMS alkali metal atom gas chamber (3) generates a Faraday magneto-optical rotation effect on the incident light, so that the polarization direction of the incident light is rotated by 90° and then incident on the second polarization beam splitting prism (4); 5) The second polarization beam splitter (4) splits the laser light outputted by the MEMS alkali metal atom gas chamber (3) into two beams, one beam being outputted through the substrate wafer (8) as a chip-based Faraday active optical clock laser, and the other beam being incident on the active optical clock resonant cavity mirror (7); 6) The active optical clock resonant cavity mirror (7) reflects a portion of the incident laser back to the semiconductor laser diode (1), so as to achieve continuous oscillation and frequency stabilization of the laser between the semiconductor laser diode (1) and the active optical clock resonant cavity mirror (7); wherein the cavity attenuation rate κ is determined by adjusting the reflectivity of the active optical clock resonant cavity mirror (7) and the transmittance of the MEMS alkali metal atom gas chamber (3), and the gain attenuation rate Γ is changed by adjusting the transmission bandwidth of the MEMS alkali metal atom gas chamber (3), so that κ>Γ, thereby making the laser work in the bad cavity area.

10. The method according to claim 9, characterized in that A first permanent magnet (5) and a second permanent magnet (6) are provided at both ends of the MEMS alkali metal atom gas chamber (3) for generating a uniform magnetic field along the light propagation direction in the MEMS alkali metal atom gas chamber (3); the first polarization beam splitter prism (2), the second polarization beam splitter prism (4), the MEMS alkali metal atom gas chamber (3), the first permanent magnet (5) and the second permanent magnet (6) form a Faraday atomic filter.

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