Optical device and method for improving atomic beam cooling effect

Abstract

The invention discloses an optical device and method for improving the atomic beam cooling effect. The optical device comprises an atomic furnace, a flange plate, a bent pipe, a capillary array, a vacuum cavity, a flat-top cooling light shaping light cylinder, a cooling window, a cooling light reflector, a detection light shaping light cylinder, a detection window, a detection light reflector, a fluorescence collecting device and the like. By adopting a flat-topped beam cascade cooling mode, the action range of cooling light is extended while the action uniformity of the cooling light and atoms is improved, and the atomic beam cooling efficiency is enhanced by combining the flexible combination of sectional cooling light power and frequency detuning; a large-flux, narrow-beam-width and high-collimation matter wave interference wave source is provided for development of quantum sensors such as atomic gyroscopes and atomic clocks.

Description

Technical Field

[0001] The present invention relates to the field of laser cooling technology, and in particular to an optical device and method for improving the cooling effect of an atomic beam. Background Art

[0002] With the vigorous development of atomic physics and quantum optics, quantum precision measurement technology, with its superior theoretical measurement accuracy and sensitivity, has shown great development potential and application value in the fields of inertial navigation, time-frequency benchmarks, and gravity measurement. In quantum sensors such as atomic interferometer gyroscopes and atomic clocks, it is first necessary to decelerate atoms through the interaction between lasers and atoms to achieve efficient atomic coherent manipulation. Compared with atomic clusters based on three-dimensional laser cooling, the use of atomic beams as interference wave sources can eliminate measurement dead zones in time, greatly improve the data update rate, and take into account the advantages of high precision and large bandwidth.

[0003] The earliest atomic beam cooling experiment used cooling light with a frequency corresponding to the absorption peak to cool the sodium atom beam. Subsequently, the cooling temperature of the atomic beam can be further reduced by changing the magnetic field, laser frequency sweeping, etc. However, these methods usually use Gaussian beams, and the uniformity of interaction with atoms is poor. The introduction of magneto-optical trap and polarization gradient cooling technology has broken through the Doppler cooling limit of atoms. However, this method reduces the lateral diffusion speed of atoms at the expense of the atomic beam flux, and requires the installation of additional gradient magnetic field coils, which is not conducive to improving the system signal-to-noise ratio and stability. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one purpose of the present invention is to propose an optical device and method for improving the cooling effect of atomic beams, by adopting a cascaded flat-top beam cooling method, while improving the uniformity of the cooling spot, extending the range of action of the cooling light and atoms, and combining the flexible combination of segmented cooling light power and frequency detuning to achieve enhanced atomic beam cooling efficiency, and provide a high-coherence matter wave source for the development of quantum sensors such as atomic gyroscopes and atomic clocks.

[0005] In order to solve the above problems, the present invention provides an optical device for improving the cooling effect of atomic beam: comprising a vacuum tube with a vacuum cavity, one end of the vacuum tube is connected to the atomic furnace via a capillary array, a second flange, a bent pipe and a first flange in sequence, and the other end of the vacuum tube is provided with a vertical cooling light reflector, a horizontal cooling light reflector, a detection light shaping light cylinder, a detection light reflector and a fluorescence collection device;

[0006] The vacuum tube is also provided with a first flat-top cooling light shaping light cylinder, a second flat-top cooling light shaping light cylinder, a third flat-top cooling light shaping light cylinder, a fourth flat-top cooling light shaping light cylinder, a fifth flat-top cooling light shaping light cylinder, a sixth flat-top cooling light shaping light cylinder, a first cooling window, a second cooling window, a third cooling window, a fourth cooling window, a first detection window, a second detection window and a third detection window;

[0007] The atoms in the atomic furnace diffuse into the capillary array along the bent pipe under the action of heating. The atomic furnace and the bent pipe are connected by a first flange, and the other end of the bent pipe is fixed to one end of the vacuum chamber through a second flange. The capillary array is located in the vacuum chamber and is connected to the bent pipe through a thread. Six flat-top cooling light shaping cylinders are installed on the periphery of the vacuum chamber, wherein the first flat-top cooling light shaping cylinder, the second flat-top cooling light shaping cylinder and the third flat-top cooling light shaping cylinder are located in the vertical direction, and the fourth flat-top cooling light shaping cylinder, the fifth flat-top cooling light shaping cylinder and the sixth flat-top cooling light shaping cylinder are located in the horizontal direction.

[0008] Preferably, the first flat-top cooling light shaping light tube outputs a larger frequency detuning of the cooling light than the second flat-top cooling light shaping light tube, and the second flat-top cooling light shaping light tube outputs a larger frequency detuning of the cooling light than the third flat-top cooling light shaping light tube; similarly, the fourth flat-top cooling light shaping light tube outputs a larger frequency detuning of the cooling light than the fifth flat-top cooling light shaping light tube, and the fifth flat-top cooling light shaping light tube outputs a larger frequency detuning of the cooling light than the sixth flat-top cooling light shaping light tube.

[0009] Preferably, the cooling light power output by the first flat-top cooling light shaping light tube is greater than the cooling light power output by the second flat-top cooling light shaping light tube, and the cooling light power output by the second flat-top cooling light shaping light tube is greater than the cooling light power output by the third flat-top cooling light shaping light tube; the cooling light power output by the fourth flat-top cooling light shaping light tube is greater than that output by the fifth flat-top cooling light shaping light tube, and the cooling light power output by the fifth flat-top cooling light shaping light tube is greater than that output by the sixth flat-top cooling light shaping light tube.

[0010] Preferably, the flat-top cooling light shaping tube comprises a cooling fiber adapter plate, a short-focus lens, a first Powell prism, a first cylindrical lens, a second Powell prism, and a second cylindrical lens; the cooling light enters the flat-top cooling light shaping tube via a transmission optical fiber fixed on the cooling fiber adapter plate, the cooling fiber adapter plate is located at the focal length of the short-focus lens, and the cooling light transmitted at a specific divergence angle is collimated under the action of the short-focus lens; the collimated cooling light is incident on the vertex of the first Powell prism, the beam size remains unchanged in the direction parallel to the edge where the vertex is located, and the beam diverges in the direction perpendicular to the edge where the vertex is located; the top of the cylinder of the first cylindrical lens is placed parallel to the vertex edge of the first Powell prism, and the cooling light passes through the first cylindrical lens. , the diameter of the light beam in the direction parallel to the top of the cylinder remains unchanged, and the divergent light beam in the direction perpendicular to the top of the cylinder is collimated, so as to obtain a collimated straight line light spot with a flat-top distribution of light intensity; the second Powell prism is placed at right angles to the top angle edges of the first Powell prism, and the collimated straight line light spot is incident on the top angle of the second Powell prism, and the size of the light beam in the direction parallel to the edge where the top angle is located remains unchanged, and the light beam diverges in the direction perpendicular to the edge where the top angle is located; the top of the cylinder of the second cylindrical lens is placed parallel to the top angle edge of the second Powell prism, and after the cooling light passes through the second cylindrical lens, the size of the light beam in the direction parallel to the top of the cylinder remains unchanged, and the divergent light beam in the direction perpendicular to the top of the cylinder is collimated, so as to obtain a collimated square light spot with a flat-top distribution of light intensity.

[0011] Preferably, the detection light shaping tube includes a detection fiber adapter plate, a collimating lens, a short-focus cylindrical lens, and a long-focus cylindrical lens; the detection light enters the detection light shaping tube via a transmission optical fiber fixed on the detection fiber adapter plate, the detection fiber adapter plate is located at the focal length of the collimating lens, and the detection light transmitted at a specific divergence angle is collimated under the action of the collimating lens; after the collimated detection light enters the short-focus cylindrical lens, the light beam remains collimated in the direction parallel to the top of the cylinder, and the collimated light beam is focused in the direction perpendicular to the top of the cylinder; the top of the cylinder of the long-focus cylindrical lens is placed parallel to the top of the cylinder of the short-focus cylindrical lens, and the distance between the long-focus cylindrical lens and the short-focus cylindrical lens is the sum of the focal lengths of the two, and after the detection light passes through the long-focus focusing lens, the light beam remains collimated in the direction parallel to the top of the cylinder, and the size remains unchanged, and the light beam is collimated in the direction perpendicular to the top of the cylinder, and the size is enlarged to form a long strip of collimated light spot.

[0012] Preferably, the first flat-top cooling light shaping cylinder and the fourth flat-top cooling light shaping cylinder are placed close to the atom emission end face of the capillary array.

[0013] Preferably, both the vertical cooling light reflector and the horizontal cooling light reflector have the function of a cooling light quarter-wave plate, and a high-reflective film of the cooling light wavelength is coated on the lower surface of the reflector, so that the polarization direction of the reflected light is orthogonal to that of the incident light.

[0014] Preferably, the light-transmitting surfaces of the first cooling window, the second cooling window, the third cooling window and the fourth cooling window are all coated with a cooling light wavelength anti-reflection film; the light-transmitting surfaces of the first detection window, the second detection window and the third detection window are all coated with a detection light wavelength anti-reflection film.

[0015] A working method of an optical device for improving the cooling effect of an atomic beam, wherein the light intensity output by a first flat-top cooling light shaping light cylinder, a second flat-top cooling light shaping light cylinder and a third flat-top cooling light shaping light cylinder has a collimated square light spot with a flat-top distribution, passes through a first cooling window and a second cooling window located in the vertical direction of a vacuum chamber in sequence, and then passes through the second cooling window in the opposite direction via a vertical cooling light reflecting mirror to return to the vacuum chamber, thereby forming a cooling light standing wave field in the vertical direction; the light intensity output by a fourth flat-top cooling light shaping light cylinder, a fifth flat-top cooling light shaping light cylinder and a sixth flat-top cooling light shaping light cylinder has a collimated square light spot with a flat-top distribution, passes through a third cooling window and a fourth cooling window located in the horizontal direction of the vacuum chamber in sequence, and then passes through the fourth cooling window in the opposite direction via a horizontal cooling light reflecting mirror to return to the vacuum chamber, thereby forming a cooling light standing wave field in the horizontal direction; the atomic beam ejected from a capillary array , under the action of the two-dimensional standing wave field with gradually decreasing frequency detuning and power composed of cascaded multi-segment flat-top cooling light, the lateral temperature of the atoms is cooled, and the cooled atomic beam moves to the detection light shaping tube at the other end of the vacuum chamber; the long strip collimated light spot output by the detection light shaping tube passes through the first detection window and the second detection window in turn, and then passes through the second detection window in the opposite direction through the detection light reflector to return to the vacuum chamber, forming a detection light standing wave field; the fluorescence collection device is installed in the vertical direction of the detection light transmission, and the detection light interacts with the atomic beam to emit fluorescence, which is collected by the fluorescence collection device through the third detection window; the fluorescence collection device converts the collected light signal into an electrical signal; by adjusting the cooling light power and frequency detuning parameters output by each flat-top cooling light shaping tube, observing the change of the fluorescence detection signal amplitude to the maximum, so as to determine the specific value of the optimal parameter of each cooling light segment.

[0016] The advantages of the present invention compared with the prior art are:

[0017] The present invention discloses an optical device and method for improving the cooling effect of an atomic beam. By adopting a flat-top beam to replace a traditional Gaussian beam to cool the atomic beam, the uniformity of the interaction between the cooling light and atoms is improved, and the cooling efficiency of the atomic beam is enhanced. This provides a matter wave interference source with large flux, narrow beam width, and high collimation for the development of quantum sensors such as atomic gyroscopes and atomic clocks.

[0018] The present invention provides an optical device and method for improving the cooling effect of an atomic beam. The hot atoms are preliminarily collimated by a capillary array. The atomic beam ejected from the capillary array immediately enters a cascaded multi-segment cooling light field. On the one hand, the effective length of the cooling light is extended. On the other hand, the power and frequency detuning of each segment of cooling light can be flexibly combined to further optimize the cooling effect of the atomic beam. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is a structural schematic diagram of the present invention;

[0021] Figure 2 It is a left view of the cooling zone part in the present invention;

[0022] Figure 3 It is a structural schematic diagram of the flat-top cooling light shaping light cylinder in the present invention;

[0023] Figure 4 It is a schematic diagram of the structure of the detection light shaping light cylinder in the present invention.

[0024] In the figure: 1, atomic furnace; 2-1, first flange; 2-2, second flange; 3, elbow; 4, capillary array; 5, vacuum chamber; 6-1, first flat-top cooling light shaping tube; 6-2, second flat-top cooling light shaping tube; 6-3, third flat-top cooling light shaping tube; 6-4, fourth flat-top cooling light shaping tube; 6-5, fifth flat-top cooling light shaping tube; 6-6, sixth flat-top cooling light shaping tube; 7-1, first cooling window; 7-2, second cooling window; 7-3, third cooling window; 7-4, fourth cooling window; 8-1, vertical cooling light reflector; 8-2, horizontal cooling light reflector; 9, detection light shaping tube; 10-1, first detection window; 10-2, second detection window; 10-3, third detection window; 11, detection light reflector; 12, fluorescence collection device;

[0025] 601, cooling optical fiber adapter plate; 602, short focus lens; 603, first Powell prism; 604, first cylindrical lens; 605, second Powell prism; 606, second cylindrical lens;

[0026] 901, detection optical fiber adapter plate; 902, collimating lens; 903, short-focus cylindrical lens; 904, long-focus cylindrical lens. DETAILED DESCRIPTION

[0027] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0028] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0029] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0030] The present invention provides an optical device and method for improving the cooling effect of an atomic beam, such as Figure 1 and Figure 2 As shown, it includes an atomic furnace 1, a first flange 2-1, a bent pipe 3, a second flange 2-2, a capillary array 4, a vacuum chamber 5, a first flat-top cooling light shaping light cylinder 6-1, a second flat-top cooling light shaping light cylinder 6-2, a third flat-top cooling light shaping light cylinder 6-3, a fourth flat-top cooling light shaping light cylinder 6-4, a fifth flat-top cooling light shaping light cylinder 6-5, a sixth flat-top cooling light shaping light cylinder 6-6, a first cooling window 7-1, a second cooling window 7-2, a third cooling window 7-3, a fourth cooling window 7-4, a vertical cooling light reflector 8-1, a horizontal cooling light reflector 8-2, a detection light shaping light cylinder 9, a first detection window 10-1, a second detection window 10-2, a third detection window 10-3, a detection light reflector 11 and a fluorescence collecting device 12.

[0031] Under the action of heating, the rubidium (Rb) atoms in the atomic furnace 1 diffuse along the curved pipe 3 into the capillary array 4. The capillary array 4 is composed of a group of stainless steel capillaries stacked in parallel in a stainless steel tube sleeve with an inner diameter of 3 mm and a length of 20 mm. The inner diameter of the capillary is 100 μm, the outer diameter is 200 μm, and the length is 20 mm. The capillary array 4 can achieve preliminary collimation of the Rb atomic beam. The atomic furnace 1 and the curved pipe 3 are connected by a first flange 2-1, and the other end of the curved pipe 3 is fixed to one end of the vacuum chamber 5 through a second flange 2-2. The capillary array 4 is located in the vacuum chamber 5 and is connected to the curved pipe 3 through a thread. Six flat-top cooling light shaping cylinders are installed on the periphery of the vacuum chamber 5, wherein the first flat-top cooling light shaping cylinder 6-1, the second flat-top cooling light shaping cylinder 6-2 and the third flat-top cooling light shaping cylinder 6-3 are located in the vertical direction, and the fourth flat-top cooling light shaping cylinder 6-4, the fifth flat-top cooling light shaping cylinder 6-5 and the sixth flat-top cooling light shaping cylinder 6-6 are located in the horizontal direction. The first flat-top cooling light shaping cylinder 6-1 and the fourth flat-top cooling light shaping cylinder 6-4 are placed close to the atom exit end face of the capillary array 4, and the spacing between the three flat-top cooling light shaping cylinders in the same direction is as small as possible, so that the Rb atomic beam enters the cooling zone as soon as it is ejected, which can minimize the width of the atomic beam after cooling.

[0032] Figure 3The schematic diagram of the structure of the flat-top cooling light shaping tube includes a cooling fiber adapter plate 601, a short-focus lens 602, a first Powell prism 603, a first cylindrical lens 604, a second Powell prism 605 and a second cylindrical lens 606. The cooling light enters the flat-top cooling light shaping tube via the transmission optical fiber fixed on the cooling fiber adapter plate 601. The focal length of the short-focus lens 602 is 6 mm. The cooling fiber adapter plate 601 is located at the focal length of the short-focus lens 602. The cooling light is collimated under the action of the short-focus lens 602, and the spot diameter is 1 mm. The collimated cooling light is incident on the vertex of the first Powell prism 603, and its vertex angle is 30°. The beam size remains unchanged in the direction parallel to the edge where the vertex angle is located, and the beam diverges in the direction perpendicular to the edge where the vertex angle is located. The top of the cylinder of the first cylindrical lens 604 is placed parallel to the vertex of the first Powell prism 603. After the cooling light passes through the first cylindrical lens 604, the beam size remains unchanged in the direction parallel to the top of the cylinder, and the divergent beam is collimated in the direction perpendicular to the top of the cylinder, obtaining a collimated linear spot with a flat-top distribution of light intensity, with a spot length of 20 mm and a width of 1 mm. The second Powell prism 605 is placed orthogonally to the vertex of the first Powell prism 603, and the collimated linear spot is incident on the vertex of the second Powell prism 603, which has a vertex angle of 30°. The beam size remains unchanged in the direction parallel to the vertex, and the beam diverges in the direction perpendicular to the vertex. The top of the cylinder of the second cylindrical lens 606 is placed parallel to the top angle edge of the second Powell prism 605. After the cooling light passes through the second cylindrical lens 606, the size of the light beam in the direction parallel to the top of the cylinder remains unchanged, and the divergent light beam in the direction perpendicular to the top of the cylinder is collimated to obtain a collimated square light spot with a flat-top distribution of light intensity, and the length and width of the light spot are both 20 mm.

[0033] The flat-top collimated square light spots output by the first flat-top cooling light shaping light tube 6-1, the second flat-top cooling light shaping light tube 6-2 and the third flat-top cooling light shaping light tube 6-3 pass through the first cooling window 7-1 and the second cooling window 7-2 located in the vertical direction of the vacuum chamber 5 in turn, and then pass through the second cooling window 7-2 in the opposite direction via the vertical cooling light reflecting mirror 8-1 to return to the vacuum chamber, forming a cooling light standing wave field in the vertical direction; the collimated square light spots output by the fourth flat-top cooling light shaping light tube 6-4, the fifth flat-top cooling light shaping light tube 6-5 and the sixth flat-top cooling light shaping light tube 6-6 pass through the third cooling window 7-3 and the fourth cooling window 7-4 located in the horizontal direction of the vacuum chamber 5 in turn, and then pass through the fourth cooling window 7-4 in the opposite direction via the horizontal cooling light reflecting mirror 8-2 to return to the vacuum chamber, forming a cooling light standing wave field in the horizontal direction. The light-transmitting surfaces of the first cooling window 7-1, the second cooling window 7-2, the third cooling window 7-3 and the fourth cooling window 7-4 are all coated with 780nm anti-reflection film. The vertical cooling light reflector 8-1 and the horizontal cooling light reflector 8-2 both have the function of a 780nm quarter-wave plate, and a 780nm high-reflection film is coated on the lower surface of the reflector, which can make the polarization direction of the reflected light orthogonal to the polarization direction of the incident light, realizing the polarization gradient cooling effect.

[0034] Due to the Doppler effect in the atomic cooling process, the frequency of the cooling light is 87 Rb atomic D2 line 5 S 1 / 2 F=2→ 5 P 3 / 2 The F'=3 resonant transition has a red detuning, and the Doppler shift decreases as the atomic transverse velocity decreases. Therefore, in order to obtain a better cooling effect, the frequency detuning of the segmented cooling light relative to its resonant transition decreases in sequence, that is, the frequency detuning of the cooling light output by the first flat-top cooling light shaping light tube 6-1 is greater than that of the second flat-top cooling light shaping light tube 6-2, and the frequency detuning of the cooling light output by the second flat-top cooling light shaping light tube 6-2 is greater than that of the third flat-top cooling light shaping light tube 6-3; similarly, the frequency detuning of the cooling light output by the fourth flat-top cooling light shaping light tube 6-4 is greater than that of the fifth flat-top cooling light shaping light tube 6-5, and the frequency detuning of the cooling light output by the fifth flat-top cooling light shaping light tube 6-5 is greater than that of the sixth flat-top cooling light shaping light tube 6-6. In order to further enhance the cooling efficiency, the power of the segmented cooling light is also reduced successively, that is, the cooling light power output by the first flat-top cooling light shaping light tube 6-1 is greater than that of the second flat-top cooling light shaping light tube 6-2, and the cooling light power output by the second flat-top cooling light shaping light tube 6-2 is greater than that of the third flat-top cooling light shaping light tube 6-3; similarly, the cooling light power output by the fourth flat-top cooling light shaping light tube 6-4 is greater than that of the fifth flat-top cooling light shaping light tube 6-5, and the cooling light power output by the fifth flat-top cooling light shaping light tube 6-5 is greater than that of the sixth flat-top cooling light shaping light tube 6-6.

[0035] The atomic beam ejected from the capillary array 4 is cooled in lateral temperature under the action of a two-dimensional standing wave field with gradually decreasing frequency detuning and power composed of cascaded multi-segment flat-top cooling light. The cooled atomic beam moves to the detection light shaping tube 9 located at the other end of the vacuum chamber 5. Figure 4 The schematic diagram of the structure of the detection light shaping tube includes a detection fiber adapter plate 901, a collimating lens 902, a short-focus cylindrical lens 903 and a long-focus cylindrical lens 904. The detection light enters the detection light shaping tube 9 through the transmission optical fiber fixed on the detection fiber adapter plate 901. The focal length of the collimating lens 902 is 16 mm. The detection fiber adapter plate 901 is located at the focal length of the collimating lens 902. The detection light is collimated by the collimating lens 902, and the spot diameter is 4 mm. After the collimated detection light enters the short-focus cylindrical lens 903, the light beam is collimated in the direction parallel to the top of the cylinder, and the collimated light beam is focused in the direction perpendicular to the top of the cylinder. The focal length of the short-focus cylindrical lens 903 is 10 mm. The top of the cylinder of the long-focus cylindrical lens 904 is placed parallel to the top of the cylinder of the short-focus cylindrical lens 903. The focal length of the long-focus cylindrical lens 904 is 50 mm, and the distance between the long-focus cylindrical lens 904 and the short-focus cylindrical lens 905 is 60 mm. After the detection light passes through the telephoto focusing lens 905, the light beam in the direction parallel to the top of the cylinder is collimated, that is, the size is still 4 mm, and the light beam in the direction perpendicular to the top of the cylinder is collimated, and the size is magnified 5 times to 20 mm, forming a long strip collimated light spot. In the atomic detection optical path, a long strip aperture is usually installed in front of the circular light spot output by the detection light collimator. The present invention shapes the detection light into a long strip light spot through an optical shaping method, thereby avoiding the waste of laser power and improving the power density of the detection light.

[0036] The long strip collimated light spot output by the detection light shaping tube 9 passes through the first detection window 10-1 and the second detection window 10-2 in turn, and then passes through the second detection window 10-2 in the opposite direction via the detection light reflector 11 and returns to the vacuum chamber 5, forming a detection light standing wave field. 87 Rb atomic D2 line 5 S 1 / 2 F=2→ 5 P 3 / 2F'=3 transition line resonance. The fluorescence collecting device 12 is installed in the vertical direction of the detection light transmission. The detection light reacts with the atomic beam to emit fluorescence, which is collected by the fluorescence collecting device through the third detection window 10-3. The light-transmitting surfaces of the first detection window 10-1, the second detection window 10-2 and the third detection window 10-3 are all coated with 780nm anti-reflection film. The fluorescence collecting device 12 converts the collected light signal into an electrical signal, and the amplitude of the electrical signal can reflect the flux size of the atomic beam. The frequency detuning of the cooling light output by the first flat-top cooling light shaping tube 6-1 and the fourth flat-top cooling light shaping tube 6-4 is recorded as δf (which can be initially set to the atomic natural line width), and the power is recorded as P (which can be initially set to the saturated light intensity); the frequency detuning of the cooling light output by the second flat-top cooling light shaping tube 6-2 and the fifth flat-top cooling light shaping tube 6-5 is recorded as δf-△f, and the power is recorded as P-△P; the frequency detuning of the cooling light output by the third flat-top cooling light shaping tube 6-3 and the sixth flat-top cooling light shaping tube 6-6 is recorded as δf-△f-△f', and the power is recorded as P-△P-△P'. By adjusting the frequency detuning and power of each cooling light segment and observing the change in the amplitude of the fluorescence detection signal to the maximum, the specific values ​​of the parameters δf, △f, △f', P, △P and △P' can be determined.

[0037] In the present invention, the atomic furnace may also contain cesium (Cs) atoms or ytterbium (Yb) atoms, and the corresponding cooling light and detection light wavelengths will change accordingly, which is not limited in the embodiment of the present invention.

[0038] In the present invention, atomic furnaces can be set at both ends of the vacuum chamber, and a detection zone for the opposing atomic beams can be set immediately after the cooling zone to achieve cooling of the atomic beams moving towards each other at both ends; a selection zone and an interference zone can also be added after the cooling zone to increase corresponding functional windows, and the embodiments of the present invention do not limit this.

[0039] The present invention and its embodiments are described above, and such description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if ordinary technicians in the field are inspired by it, without departing from the purpose of the invention, they can design a structure and embodiment similar to the technical solution without creativity, which should belong to the protection scope of the present invention.

Claims

1. An optical device for improving the cooling effect of an atomic beam, characterized in that: It comprises a vacuum tube with a vacuum cavity, one end of which is connected to the atomic reactor via a capillary array, a second flange, a bent pipe and a first flange in sequence, and the other end of the vacuum tube is provided with a vertical cooling light reflector, a horizontal cooling light reflector, a detection light shaping light cylinder, a detection light reflector and a fluorescence collection device; The vacuum tube is also provided with a first flat-top cooling light shaping light cylinder, a second flat-top cooling light shaping light cylinder, a third flat-top cooling light shaping light cylinder, a fourth flat-top cooling light shaping light cylinder, a fifth flat-top cooling light shaping light cylinder, a sixth flat-top cooling light shaping light cylinder, a first cooling window, a second cooling window, a third cooling window, a fourth cooling window, a first detection window, a second detection window and a third detection window; The atoms in the atomic furnace diffuse into the capillary array along the bent pipe under the action of heating; the atomic furnace and the bent pipe are connected by a first flange, and the other end of the bent pipe is fixed to one end of the vacuum chamber by a second flange; the capillary array is located in the vacuum chamber and is connected to the bent pipe by a thread; six flat-top cooling light shaping cylinders are installed on the periphery of the vacuum chamber, wherein the first flat-top cooling light shaping cylinder, the second flat-top cooling light shaping cylinder and the third flat-top cooling light shaping cylinder are located in the vertical direction, and the fourth flat-top cooling light shaping cylinder, the fifth flat-top cooling light shaping cylinder and the sixth flat-top cooling light shaping cylinder are located in the horizontal direction.

2. An optical device for improving the cooling effect of an atomic beam according to claim 1, characterized in that: The frequency detuning amount of cooling light output by the first flat-top cooling light shaping light tube is larger than that of the second flat-top cooling light shaping light tube, and the frequency detuning amount of cooling light output by the second flat-top cooling light shaping light tube is larger than that of the third flat-top cooling light shaping light tube; Similarly, the cooling light frequency detuning amount output by the fourth flat-top cooling light shaping light tube is larger than that output by the fifth flat-top cooling light shaping light tube, and the cooling light frequency detuning amount output by the fifth flat-top cooling light shaping light tube is larger than that output by the sixth flat-top cooling light shaping light tube.

3. The optical device for improving the cooling effect of an atomic beam according to claim 1, characterized in that: The cooling light power output by the first flat-top cooling light shaping light tube is greater than the cooling light power output by the second flat-top cooling light shaping light tube, and the cooling light power output by the second flat-top cooling light shaping light tube is greater than the cooling light power output by the third flat-top cooling light shaping light tube; the cooling light power output by the fourth flat-top cooling light shaping light tube is greater than that output by the fifth flat-top cooling light shaping light tube, and the cooling light power output by the fifth flat-top cooling light shaping light tube is greater than that output by the sixth flat-top cooling light shaping light tube.

4. The optical device for improving the cooling effect of an atomic beam according to claim 1, characterized in that: The flat-top cooling light shaping tube comprises a cooling optical fiber adapter plate, a short-focus lens, a first Powell prism, a first cylindrical lens, a second Powell prism, and a second cylindrical lens; The cooling light enters the flat-top cooling light shaping tube via a transmission optical fiber fixed on a cooling optical fiber adapter plate. The cooling optical fiber adapter plate is located at the focal length of the short-focus lens. The cooling light transmitted at a specific divergence angle is collimated under the action of the short-focus lens. The collimated cooling light is incident on the vertex angle of the first Powell prism, and the size of the light beam remains unchanged in the direction parallel to the edge where the vertex angle is located, and the light beam diverges in the direction perpendicular to the edge where the vertex angle is located; the top of the cylinder of the first cylindrical lens is placed parallel to the vertex angle edge of the first Powell prism, and after the cooling light passes through the first cylindrical lens, the diameter of the light beam remains unchanged in the direction parallel to the top of the cylinder, and the divergent light beam is collimated in the direction perpendicular to the top of the cylinder, so as to obtain a collimated straight line light spot with a flat-top distribution of light intensity; the second Powell prism is placed orthogonally to the vertex angle edge of the first Powell prism, and the collimated straight line light spot is incident on the vertex angle of the second Powell prism, and the size of the light beam remains unchanged in the direction parallel to the edge where the vertex angle is located, and the light beam diverges in the direction perpendicular to the vertex angle; the top of the cylinder of the second cylindrical lens is placed parallel to the vertex angle edge of the second Powell prism, and after the cooling light passes through the second cylindrical lens, the size of the light beam remains unchanged in the direction parallel to the top of the cylinder, and the divergent light beam is collimated in the direction perpendicular to the top of the cylinder, so as to obtain a collimated square light spot with a flat-top distribution of light intensity.

5. The optical device for improving the cooling effect of an atomic beam according to claim 1, characterized in that: The detection light shaping tube includes a detection optical fiber adapter plate, a collimating lens, a short-focus cylindrical lens, and a long-focus cylindrical lens; The detection light enters the detection light shaping light cylinder through the transmission optical fiber fixed on the detection optical fiber adapter plate. The detection optical fiber adapter plate is located at the focal length of the collimating lens. The detection light transmitted at a specific divergence angle is collimated under the action of the collimating lens. After the collimated detection light enters the short-focus cylindrical lens, the light beam maintains collimated transmission in the direction parallel to the top of the cylinder, and the collimated light beam is focused in the direction perpendicular to the top of the cylinder. The top of the cylinder of the long-focus cylindrical lens is placed parallel to the top of the cylinder of the short-focus cylindrical lens, and the distance between the long-focus cylindrical lens and the short-focus cylindrical lens is the sum of the focal lengths of the two. After the detection light passes through the long-focus focusing lens, the light beam maintains collimated transmission in the direction parallel to the top of the cylinder, and the size remains unchanged. The light beam is collimated in the direction perpendicular to the top of the cylinder, and the size is enlarged to form a long strip of collimated light spot.

6. The optical device for improving the cooling effect of an atomic beam according to claim 1, characterized in that: The first flat-top cooling light shaping cylinder and the fourth flat-top cooling light shaping cylinder are placed close to the atom emission end face of the capillary array.

7. The optical device for improving the cooling effect of an atomic beam according to claim 1, characterized in that: The vertical cooling light reflector and the horizontal cooling light reflector both have the function of a cooling light quarter wave plate, and a high-reflection film of the cooling light wavelength is plated on the lower surface of the reflector, so that the polarization direction of the reflected light is orthogonal to that of the incident light.

8. The optical device for improving the cooling effect of an atomic beam according to claim 1, characterized in that: The light-transmitting surfaces of the first cooling window, the second cooling window, the third cooling window and the fourth cooling window are all coated with a cooling light wavelength anti-reflection film; the light-transmitting surfaces of the first detection window, the second detection window and the third detection window are all coated with a detection light wavelength anti-reflection film.

9. A method for operating an optical device for improving the cooling effect of an atomic beam as claimed in claim 1, characterized in that: The light intensity output by the first flat-top cooling light shaping light cylinder, the second flat-top cooling light shaping light cylinder and the third flat-top cooling light shaping light cylinder has a collimated square light spot with a flat-top distribution, which passes through the first cooling window and the second cooling window located in the vertical direction of the vacuum chamber in sequence, and then passes through the second cooling window in the opposite direction via the vertical cooling light reflecting mirror to return to the vacuum chamber, forming a cooling light standing wave field in the vertical direction; the light intensity output by the fourth flat-top cooling light shaping light cylinder, the fifth flat-top cooling light shaping light cylinder and the sixth flat-top cooling light shaping light cylinder has a collimated square light spot with a flat-top distribution, which passes through the third cooling window and the fourth cooling window located in the horizontal direction of the vacuum chamber in sequence, Then, it passes through the fourth cooling window in the opposite direction through the horizontal cooling light reflector and returns to the vacuum chamber, forming a cooling light standing wave field in the horizontal direction; the atomic beam ejected from the capillary array is cooled in the lateral temperature under the action of the two-dimensional standing wave field with gradually decreasing frequency detuning and power composed of the cascaded multi-segment flat-top cooling light, and the cooled atomic beam moves to the detection light shaping light cylinder at the other end of the vacuum chamber; the long strip collimated light spot output by the detection light shaping light cylinder passes through the first detection window and the second detection window in turn, and then passes through the second detection window in the opposite direction through the detection light reflector and returns to the vacuum chamber, forming a detection light standing wave field; The fluorescence collecting device is installed in the vertical direction of the detection light transmission, and the detection light reacts with the atomic beam to emit fluorescence, which is collected by the fluorescence collecting device through the third detection window; the fluorescence collecting device converts the collected light signal into an electrical signal; By adjusting the cooling light power and frequency detuning parameters output by each flat-top cooling light shaping tube, and observing the change in the amplitude of the fluorescence detection signal to the maximum, the specific values ​​of the optimal parameters of each cooling light segment can be determined.

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