Chip-scale atomic diffraction optical element and preparation method thereof

Abstract

The invention relates to the technical field of micro-nano optics and atomic devices, in particular to a chip-level atomic diffraction optical element and a preparation method thereof. Comprising an SOI wafer, a getter pill chamber, an alkali metal release pill chamber, a diffraction grating, upper cover plate glass and lower cover plate glass, the getter pill chamber, the alkali metal release pill chamber and the diffraction grating are respectively arranged in the getter pill area, the alkali metal release pill area and the diffraction grating area, the getter pill chamber and the alkali metal release pill chamber penetrate through the SOI wafer, the getter pill chamber is communicated with the alkali metal release pill chamber, the alkali metal release pill chamber is communicated with the diffraction microstructure, and the diffraction microstructure is communicated with the diffraction microstructure. Getter pills are sealed in the getter pill chamber, and alkali metal release pills are sealed in the alkali metal release pill chamber. According to the original, atom steam is sealed in an unprocessed diffraction structure, a unique interference spectrum is generated, and wide-bandwidth and high-precision laser frequency offset locking under the condition of no magnetic field is realized.

Description

Technical Field

[0001] This invention relates to the field of micro-nano optics and atomic devices, specifically to a chip-scale atomic diffraction optical element and its fabrication method. Background Technology

[0002] Laser frequency stabilization is a core technology in fields such as precision spectroscopy, quantum information processing, quantum manipulation, and sensing. To achieve long-term laser frequency stability, traditional laser frequency stabilization techniques typically lock the laser to a stable reference frequency, such as the resonant frequency of an optical cavity or the inherent transition lines of atoms / molecules. Optical cavity systems offer excellent short-term stability, are relatively insensitive to frequency changes caused by power fluctuations, and support tunable frequency locking points. However, due to thermo-optical effects, the cavity resonant frequency drifts over time, resulting in poor long-term stability. In contrast, atomic spectroscopy systems, which rely on the inherent fundamental properties of atomic structure, can generate highly stable and precise optical signals. However, traditional devices are bulky and have limited frequency offset tuning capabilities (bandwidth less than 30 GHz).

[0003] Frequency offset locking technology allows the laser frequency to be stabilized at a tunable detuned frequency near the atomic resonance line, which is crucial for applications such as laser cooling, atomic trapping, and Rydberg atomic excitation. Existing frequency offset locking techniques, such as two-color atomic gas cell laser locking (DAVLL), Faraday spectroscopy, and polarization-enhanced absorption spectroscopy, require strong magnetic fields to achieve atomic energy level transitions. This not only increases system complexity but may also interfere with peripheral equipment. Furthermore, their frequency offset tuning capability is limited and they are difficult to miniaturize, failing to meet the integration requirements of chip-scale quantum devices.

[0004] In the field of chip-scale systems, optical frequency references and waveguide-integrated photonic atomic systems based on MEMS atomic gas cells have been reported, achieving ultra-low instabilities. However, MEMS atomic gas cells are often used as spectral absorption cells, with a single function, and cannot directly provide interferometric optical responses for laser frequency offset locking. Therefore, achieving tunability (i.e., frequency offset locking frequency) in a compact platform while maintaining the stability of atomic spectral lines remains a challenge. Therefore, there is an urgent need to develop a novel device that can monolithically integrate atomic media and optical functional structures on a chip, generate high-contrast, broadband interference spectra, and simultaneously achieve wide-bandwidth, tunable, miniaturized, and mass-producible laser frequency offset locking without the need for an external magnetic field. Summary of the Invention

[0005] The purpose of this invention is to propose a chip-scale atomic diffraction optical element and its fabrication method. Compared with traditional frequency offset locking techniques (such as DAVLL and Faraday spectroscopy) that rely on magnetic fields to split atomic energy levels through the Zeeman effect and thus generate frequency offset signals, this invention seals alkali metal atomic vapor in a micro-fabricated diffraction grating structure. Through the coupling mechanism of atomic dispersion and diffraction interference, a broadband interference spectrum with multiple stable points is generated under magnetic field-free conditions, achieving wide bandwidth and high precision laser frequency offset locking under magnetic field-free conditions.

[0006] Therefore, the present invention provides the following technical solution:

[0007] In a first aspect, the present invention provides a chip-level atomic diffraction optical element in an optional embodiment, comprising an SOI wafer, a getter pellet chamber, an alkali metal release pellet chamber, a diffraction grating, an upper cover glass, and a lower cover glass.

[0008] The SOI wafer has a getter pellet region, an alkali metal release pellet region, and a diffraction grating region on its device layer, with the getter pellet region and the diffraction grating region respectively located on both sides of the alkali metal release pellet region.

[0009] The getter pellet chamber, the alkali metal release pellet chamber, and the diffraction grating are respectively disposed in the getter pellet region, the alkali metal release pellet region, and the diffraction grating region, and the getter pellet chamber and the alkali metal release pellet chamber penetrate the SOI wafer. The getter pellet chamber and the alkali metal release pellet chamber are connected through a microchannel, and the alkali metal release pellet chamber is connected to the diffraction grating through a microchannel. The getter pellet chamber is sealed with a getter pellet, and the alkali metal release pellet chamber is sealed with an alkali metal release pellet.

[0010] In this invention, both getter pellets and alkali metal releasing pellets are commonly used pellets in the art. Typically, but not exclusively, the getter pellets are high-porosity (≥40%) active getter alloy pellets formed by vacuum sintering of zirconium and other transition metals. Alkali metal releasing pellets: rubidium atoms (rubidium molybdate (33%), zirconium (56%), aluminum (11%)) or cesium atoms (cesium molybdate (33%), zirconium (56%), aluminum (11%)).

[0011] The upper cover glass and the lower cover glass are bonded to the device layer and silicon substrate layer of the SOI wafer respectively by anodic bonding to form a completely sealed vacuum cavity. The surface of the upper cover glass is coated with an anti-reflection film, and the surface of the lower cover glass is coated with a high-reflection film.

[0012] Preferably, the SOI wafer is a single-crystal silicon wafer with a crystal phase of 100; the device layer thickness of the SOI wafer is 150 μm, the thickness of the intermediate silicon oxide layer is 2 μm, and the thickness of the silicon substrate layer is 1500 μm.

[0013] Preferably, the upper cover glass and the lower cover glass are of type BF33 and have a thickness of 500 μm; the antireflective coating has a thickness of 780 nm and the high reflective coating has a thickness of 780 nm; at a wavelength of 778 nm, the light transmittance of the upper cover glass exceeds 99.7% and the light reflectance of the lower cover glass exceeds 99.9%.

[0014] Preferably, the diffraction grating is a Fresnel diffraction grating; the diameter of the diffraction grating is 2 mm, the focal length is 7 cm, and the diffraction ring spacing is from 40 to 120 μm.

[0015] Preferably, the getter pellet chamber is cylindrical with a diameter of 1 mm and a height of 0.6 mm; and / or, the alkali metal release pellet chamber is cylindrical with a diameter of 1.5 mm and a height of 1 mm.

[0016] Preferably, the anodic bonding process is performed with a vacuum degree of less than 10. -5 The bonding conditions are: mbar, temperature 380℃, bonding pressure 1000N, bonding voltage 1000V, and bonding stops when the bonding current drops below 10% of the peak value.

[0017] Secondly, in an optional embodiment, the present invention provides a method for fabricating the above-mentioned chip-scale atomic diffraction optical element, comprising the following steps:

[0018] S1: After cleaning the SOI wafer, top cover glass, and bottom cover glass, spin-coat the adhesion promoter and photoresist sequentially onto the device layer of the SOI wafer. By exposing with UV light, the patterns of getter pill chambers, alkali metal release pill chambers, diffraction gratings, and microchannels on the photomask are transferred onto the photoresist. After exposure, development and drying are performed. By deep silicon etching, the patterns of getter pill chambers, alkali metal release pill chambers, diffraction gratings, and microchannels on the photoresist are transferred onto the device layer of the SOI wafer, and etching stops at the intermediate silicon oxide layer of the SOI wafer.

[0019] S2: Clean the photoresist on the device layer of the SOI wafer, and spin-coat the adhesion promoter and photoresist sequentially on the silicon substrate layer of the SOI wafer. By UV light exposure, the patterns of getter pill chambers and alkali metal release pill chambers on the mask are transferred to the photoresist. After exposure, development and drying are performed. By deep silicon etching, the patterns of getter pill chambers and alkali metal release pill chambers on the photoresist are transferred to the silicon substrate layer of the SOI wafer, and etching stops at the intermediate silicon oxide layer of the SOI wafer.

[0020] S3: The etched SOI wafer is placed in a buffered hydrofluoric acid solution to remove the intermediate silicon oxide layer in the getter pellet chamber and the alkali metal release pellet chamber. The photoresist on the silicon substrate layer of the SOI wafer is removed, and the SOI wafer is cleaned, dried with nitrogen, and baked. The top cover glass is bonded to the device layer of the SOI wafer by anodic bonding. Then, the alkali metal release pellet and getter pellet are placed in the alkali metal release pellet chamber and getter pellet chamber, respectively. The bottom cover glass is then bonded to the silicon substrate layer of the SOI wafer by anodic bonding to form a sealed vacuum cavity. The bonded SOI wafer is diced to obtain discrete atomic diffraction elements. Finally, the getter is activated at high temperature and the alkali metal is laser-excited.

[0021] Preferably, in step S3, the baking temperature is 110°C and the time is 30 minutes. The cleaning is performed using a mixed solution of concentrated sulfuric acid and hydrogen peroxide, followed by rinsing with deionized water; the concentration of the concentrated sulfuric acid is 98%, and the volume ratio of concentrated sulfuric acid to hydrogen peroxide is 3:1. The high-temperature activation temperature of the getter is 450°C; the wavelength of the laser is 780 nm, the spot size is less than 1 mm, and the power is 1 mW.

[0022] Compared with the prior art, the present invention has one of the following beneficial effects:

[0023] 1. The chip-level atomic diffraction optical element provided by the present invention seals atomic vapor in an unprocessed diffraction structure and generates a unique interference spectrum by utilizing the coupling effect of atomic dispersion and structural diffraction, thereby achieving wide bandwidth and high precision laser frequency offset locking under magnetic field-free conditions.

[0024] 2. This invention uses microfabrication technology to fabricate atomic diffraction optical elements, which are small in size, easy to mass-produce and integrate with other photonic chips, thus facilitating the miniaturization trend of quantum technology.

[0025] 3. This invention generates error signals through the interference effect of atom-photon coupling, which can achieve laser frequency offset locking without a magnetic field, thus avoiding magnetic field interference problems and making the system more compact.

[0026] 4. This invention utilizes the coupling of atomic dispersion and structural interference to generate multiple high-contrast frequency offset locking points within a bandwidth of tens of GHz.

[0027] 5. This invention uses mature MEMS technology, is compatible with wafer-level manufacturing, and has low cost and good consistency.

[0028] 6. This invention allows for flexible control of the spectral response by designing different diffraction structures (such as gratings and Fresnel rings). Attached Figure Description

[0029] The advantages of the above and / or additional aspects of this application will become apparent and readily understood in the description of the embodiments in conjunction with the following drawings, wherein:

[0030] Figure 1 This is a schematic diagram of the structure of the chip-level atomic diffraction optical element in Embodiment 1 of the present invention;

[0031] Figure 2 This is a schematic diagram illustrating the working principle of the chip-level atomic diffraction optical element in Embodiment 1 of the present invention;

[0032] Figure 3 This is the calculated interferogram of the chip-level atomic diffraction optical element in Embodiment 1 of the present invention;

[0033] Figure 4 This is a schematic diagram of the fabrication method of the chip-scale atomic diffraction optical element according to Embodiment 2 of the present invention.

[0034] 1-Getter pellet chamber, 2-Alkali metal release pellet chamber, 3-Fresnel diffraction grating, 4-BF33 glass cover plate, 5-SOI wafer, 6-Reference light, 7-Sample light, 8-Device layer and silicon substrate layer of SOI wafer, 9-Photoresist, 10-Intermediate silicon oxide layer of SOI wafer, 11-Alkali metal source, 12-Getter. Detailed Implementation

[0035] To better understand the above-mentioned objectives, features, and advantages of this application, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other.

[0036] In the following description, many specific details are set forth in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below.

[0037] The technical solution of the present invention will now be described in detail with reference to the embodiments and accompanying drawings.

[0038] Example 1

[0039] See Figure 1 This embodiment provides a chip-level atomic diffraction optical element, including an SOI wafer, a getter pellet chamber, an alkali metal release pellet chamber, a diffraction grating, an upper cover glass, and a lower cover glass;

[0040] The SOI wafer is a single-crystal silicon wafer with a crystal phase of 100. The device layer thickness of the SOI wafer is 150 μm, the thickness of the intermediate silicon oxide layer is 2 μm, and the thickness of the silicon substrate layer is 1500 μm. The top and bottom cover glass are of type BF33 and have a thickness of 500 μm.

[0041] The SOI wafer has a getter pellet region, an alkali metal release pellet region, and a diffraction grating region on its device layer. The getter pellet region and the diffraction grating region are respectively located on both sides of the alkali metal release pellet region.

[0042] A getter pellet chamber, an alkali metal release pellet chamber, and a diffraction grating are respectively disposed in the getter pellet region, the alkali metal release pellet region, and the diffraction grating region. The getter pellet chamber and the alkali metal release pellet chamber penetrate the SOI wafer. The getter pellet chamber and the alkali metal release pellet chamber are connected through a microchannel, and the alkali metal release pellet chamber and the diffraction grating are connected through a microchannel. The getter pellet chamber is sealed with a getter pellet, and the alkali metal release pellet chamber is sealed with an alkali metal release pellet. In this embodiment, the alkali metal release pellet is a rubidium atom (rubidium molybdate 33%, zirconium 56%, aluminum 11%). The getter pellet chamber is cylindrical with a diameter of 1 mm and a height of 0.6 mm, and the alkali metal release pellet chamber is cylindrical with a diameter of 1.5 mm and a height of 1 mm. The diffraction grating is a Fresnel grating structure with a diameter of 2 mm, a focal length of 7 cm, and a diffraction ring spacing of 40-120 μm.

[0043] The top and bottom cover glass are bonded to the device layer and silicon substrate layer of the SOI wafer, respectively, via anodic bonding to form a completely sealed vacuum cavity. The surface of the top cover glass is coated with an antireflective film, and the surface of the bottom cover glass is coated with a high reflective film. The thickness of the antireflective film is 780 nm, and the thickness of the high reflective film is 780 nm. At a wavelength of 778 nm, the light transmittance of the top cover glass exceeds 99.7%, and the light reflectance of the bottom cover glass exceeds 99.9%.

[0044] Example 2

[0045] See Figure 4 This embodiment provides a method for fabricating a chip-scale atomic diffraction optical element as described in Example 1, including the following steps:

[0046] S1: After cleaning the SOI wafer, top cover glass, and bottom cover glass, spin-coat hexamethyldisilazane (HMDS) tackifier and photoresist (AZ 4620) sequentially onto the device layer of the SOI wafer. Cover the photoresist with an upper mask (which has patterns of getter pill chambers, alkali metal release pill chambers, diffraction gratings, and microchannels). Expose the mask with UV light to transfer the patterns of getter pill chambers, alkali metal release pill chambers, diffraction gratings, and microchannels onto the photoresist. After exposure, develop and dry the mask. Then, use deep silicon etching to transfer the patterns of getter pill chambers, alkali metal release pill chambers, diffraction gratings, and microchannels onto the device layer of the SOI wafer. Etch until the intermediate silicon oxide layer of the SOI wafer is reached.

[0047] S2: Clean the photoresist on the device layer of the SOI wafer, and spin-coat the adhesion promoter and photoresist sequentially on the silicon substrate layer of the SOI wafer. Cover the photoresist with a lower mask (the lower mask has patterns of getter pill chambers and alkali metal release pill chambers). Expose with UV light to transfer the patterns of getter pill chambers and alkali metal release pill chambers on the mask onto the photoresist. After exposure, develop and dry. Through deep silicon etching, transfer the patterns of getter pill chambers and alkali metal release pill chambers on the photoresist onto the silicon substrate layer of the SOI wafer, and etch until the intermediate silicon oxide layer of the SOI wafer stops.

[0048] S3: Place the etched SOI wafer in a buffered hydrofluoric acid solution to remove the intermediate silicon oxide layer in the getter pellet chamber and alkali metal release pellet chamber, remove the photoresist from the silicon substrate layer of the SOI wafer, and clean the SOI wafer using a mixed solution of concentrated sulfuric acid and hydrogen peroxide, followed by rinsing with deionized water. The concentration of concentrated sulfuric acid is 98%, and the volume ratio of concentrated sulfuric acid to hydrogen peroxide is 3:1. Dry the SOI wafer with nitrogen gas and bake it on a hot plate at 110°C for 30 minutes. To remove residual moisture, anodic bonding is performed on the device layer of the SOI wafer (anodally bonding the etched silicon wafer to a 4-inch BF33 glass wafer at 380°C. The anodic bonding of the glass and silicon wafers is carried out in a bonding chamber at 380°C under a vacuum of less than 10⁻⁵ mbar. The bonding pressure is 1000 N, and the bonding voltage is maintained at 1000 V until the bonding current drops below 10% of its peak value. A force of 1000 N is applied throughout the bonding process). The process involves bonding a glass cover plate, placing alkali metal release agent pellets and getter pellets into the alkali metal release pellet chamber and getter pellet chamber, respectively, and then anoly bonding another glass cover plate onto a 4-inch BF33 glass wafer at 380°C. The anoly bonding of the glass and silicon wafers is performed in a bonding chamber at 380°C under a vacuum of less than 10⁻⁵ mbar. The bonding pressure is 1000 N, and the bonding voltage is maintained at 1000 V. The bonding process involves applying a force of 1000N to the silicon substrate of the SOI wafer until the bonding current drops below 10% of its peak value, forming a sealed vacuum cavity. The bonded SOI wafer is then diced to obtain discrete atomic diffraction elements. Finally, the atomic diffraction elements are activated with a high temperature (450°C) to activate the getter, and then excited with a laser (780nm wavelength, spot size less than 1mm, power not less than 1mW) to excite the alkali metal.

[0049] Figure 2 This is a schematic diagram of the working principle of the chip-level atomic diffraction optical element in Embodiment 1 of the present invention. The diffraction structure in the ADOE divides the incident laser into two parts: one part is reflected by the silicon surface (reference light 6), and the other part is reflected after passing through rubidium atomic vapor (sample light 7). Due to the dispersion and absorption characteristics of rubidium atoms, the two beams of light produce a phase difference, forming chirped sinusoidal interference fringes in the far field.

[0050] The core principle is as follows: The incident laser beam, after passing through a non-polarized beam splitter (NPBS, 50:50), is perpendicularly incident on the ADOE surface. Part of the laser beam is directly reflected by the silicon structure surface, forming the reference beam (6). The other part of the laser beam passes through the Rb atomic vapor in the diffraction grating region and is reflected by the buried oxide layer of the SOI wafer, forming the sample beam (7). Due to the dispersive properties of the Rb atomic vapor (refractive index varies with frequency), the sample beam experiences a frequency-dependent phase shift during transmission, while the reference beam is only affected by the optical properties of the silicon surface and remains phase-stable. The two beams superimpose in the far field after reflection, forming interference fringes. The periodicity of the fringes is determined by the phase difference: phase difference Δφ = 2πn a ·2L / λ, where n a Let n be the refractive index of the alkali metal atom (positively correlated with atomic density), L be the etching depth (150 μm), and λ be the laser wavelength (780.24 nm). When the laser frequency is scanned, n... a The frequency variation causes a change in Δφ, resulting in a chirped sinusoidal distribution of interference fringes. Near the Rb atomic absorption resonance line, the dispersion effect is significant, and the fringe density increases; further away from the resonance line, the dispersion effect weakens, and the fringe spacing increases, as shown below. Figure 3 As shown, a high-frequency (typically kHz to MHz) small-amplitude sinusoidal modulation is applied to the laser current, and a lock-in amplifier detects the light intensity signal returned from the ADOE. The lock-in amplifier extracts the component with the same modulation frequency and phase correlation. After demodulation, the original spectral fringes are converted into a zero-crossing, dispersive "S"-shaped curve, i.e., the error signal. The generated error signal is input to a PID controller. If the laser frequency deviates from the lock point, the error signal will give a non-zero value. The PID controller generates a correction voltage based on this, which is fed back to the piezoelectric ceramic or current driver of the laser to "pull back" the laser frequency and lock it at the zero-crossing point of the error signal.

[0051] Although this application has been disclosed in detail with reference to the accompanying drawings, it should be understood that these descriptions are merely exemplary and not intended to limit the application of this application. The scope of protection of this application is defined by the appended claims and may include various modifications, alterations, and equivalents of the invention without departing from the scope and spirit of this application.

Claims

1. A chip-scale atomic diffraction optical element, characterized in that, This includes SOI wafers, getter pellet chambers, alkali metal release pellet chambers, diffraction gratings, upper cover glass, and lower cover glass; The SOI wafer has a getter pellet region, an alkali metal release pellet region, and a diffraction grating region on its device layer, with the getter pellet region and the diffraction grating region respectively located on both sides of the alkali metal release pellet region. The getter pellet chamber, the alkali metal release pellet chamber, and the diffraction grating are respectively disposed in the getter pellet region, the alkali metal release pellet region, and the diffraction grating region, and the getter pellet chamber and the alkali metal release pellet chamber penetrate the SOI wafer. The getter pellet chamber and the alkali metal release pellet chamber are connected through a microchannel, and the alkali metal release pellet chamber is connected to the diffraction grating through a microchannel. The getter pellet chamber is sealed with a getter pellet, and the alkali metal release pellet chamber is sealed with an alkali metal release pellet. The upper cover glass and the lower cover glass are bonded to the device layer and silicon substrate layer of the SOI wafer respectively by anodic bonding to form a completely sealed vacuum cavity. The surface of the upper cover glass is coated with an anti-reflection film, and the surface of the lower cover glass is coated with a high-reflection film.

2. The chip-level atomic diffraction optical element according to claim 1, characterized in that, The SOI wafer is a single-crystal silicon wafer with a crystal phase of 100. The SOI wafer has a device layer thickness of 150 μm, an intermediate silicon oxide layer thickness of 2 μm, and a silicon substrate layer thickness of 1500 μm.

3. The chip-level atomic diffraction optical element according to claim 1, characterized in that, The upper and lower cover glass are of model BF33 and have a thickness of 500μm. The thickness of the antireflective coating is 780 nm, and the thickness of the high reflective coating is 780 nm. At a wavelength of 778nm, the light transmittance of the upper cover glass exceeds 99.7%, and the light reflectance of the lower cover glass exceeds 99.9%.

4. The chip-level atomic diffraction optical element according to claim 1, characterized in that, The diffraction grating is a Fresnel diffraction grating; The diffraction grating has a diameter of 2 mm, a focal length of 7 cm, and a diffraction ring spacing of 40-120 μm.

5. The chip-level atomic diffraction optical element according to claim 1, characterized in that, The getter pellet chamber is cylindrical in shape, with a diameter of 1 mm and a height of 0.6 mm; The alkali metal release pellet chamber is cylindrical in shape, with a diameter of 1.5 mm and a height of 1 mm.

6. The chip-level atomic diffraction optical element according to claim 1, characterized in that, The anodic bonding process is as follows: Vacuum degree less than 10 -5 The bonding conditions are: mbar, temperature 380℃, bonding pressure 1000N, bonding voltage 1000V, and bonding stops when the bonding current drops below 10% of the peak value.

7. A method for fabricating a chip-scale atomic diffraction optical element according to any one of claims 1-6, characterized in that, Includes the following steps: S1: After cleaning the SOI wafer, top cover glass, and bottom cover glass, spin-coat the adhesion promoter and photoresist sequentially onto the device layer of the SOI wafer. By exposing with UV light, the patterns of getter pill chambers, alkali metal release pill chambers, diffraction gratings, and microchannels on the photomask are transferred onto the photoresist. After exposure, development and drying are performed. By deep silicon etching, the patterns of getter pill chambers, alkali metal release pill chambers, diffraction gratings, and microchannels on the photoresist are transferred onto the device layer of the SOI wafer, and etching stops at the intermediate silicon oxide layer of the SOI wafer. S2: Clean the photoresist on the device layer of the SOI wafer, and spin-coat the adhesion promoter and photoresist sequentially on the silicon substrate layer of the SOI wafer. By UV light exposure, the patterns of getter pill chambers and alkali metal release pill chambers on the mask are transferred to the photoresist. After exposure, development and drying are performed. By deep silicon etching, the patterns of getter pill chambers and alkali metal release pill chambers on the photoresist are transferred to the silicon substrate layer of the SOI wafer, and etching stops at the intermediate silicon oxide layer of the SOI wafer. S3: The etched SOI wafer is placed in a buffered hydrofluoric acid solution to remove the intermediate silicon oxide layer in the getter pellet chamber and the alkali metal release pellet chamber. The photoresist on the silicon substrate layer of the SOI wafer is removed, and the SOI wafer is cleaned, dried with nitrogen, and baked. The top cover glass is bonded to the device layer of the SOI wafer by anodic bonding. Then, the alkali metal release pellet and getter pellet are placed in the alkali metal release pellet chamber and getter pellet chamber, respectively. The bottom cover glass is then bonded to the silicon substrate layer of the SOI wafer by anodic bonding to form a sealed vacuum cavity. The bonded SOI wafer is diced to obtain discrete atomic diffraction elements. Finally, the getter is activated at high temperature and the alkali metal is laser-excited.

8. The method for fabricating a chip-scale atomic diffraction optical element according to claim 7, characterized in that, In step S3, the baking temperature is 110°C and the baking time is 30 minutes.

9. The method for fabricating a chip-scale atomic diffraction optical element according to claim 7, characterized in that, In step S3, the cleaning is performed using a mixed solution of concentrated sulfuric acid and hydrogen peroxide, followed by rinsing with deionized water. The concentration of the concentrated sulfuric acid is 98%, and the volume ratio of concentrated sulfuric acid to hydrogen peroxide is 3:

1.

10. The method for fabricating a chip-scale atomic diffraction optical element according to claim 7, characterized in that, In step S3, the temperature at which the high-temperature activated getter is 450°C; The laser has a wavelength of 780nm, a spot size of less than 1mm, and a power of 1mW.

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