A Raman optical state-selective interferometer device for atomic interferometer gyroscope

Abstract

The present invention relates to a Raman light state-selective interferometer device for an atomic interference gyroscope. A polarization beam splitter prism is used to spatially split the Raman interference light, so that the two Raman interference light beams share a Raman interference collimator, thereby reducing the number of collimators. A triangular reflecting prism is used to allow the Raman state-selected light and the Raman interference light to share a polarization beam splitter prism, resulting in a compact structure and space-saving, which can effectively reduce the size of the atomic interference gyroscope device. A large flat reflector with a good surface shape is used to replace a traditional plurality of independent reflectors, thereby solving the problem that the atomic interference gyroscope has a high requirement for the parallelism of the effective wave vectors between the two Raman light beams, which makes the assembly and adjustment difficult.

Description

Technical Field

[0001] The present invention relates to the field of quantum precision measurement technology, and in particular to a Raman light state selection interference device for an atomic interferometer gyroscope. Background Art

[0002] The rapid development of atomic interferometry technologies, such as laser cooling and manipulation, in the field of quantum precision measurement has greatly promoted the development of atomic interferometer gyroscopes based on two-photon stimulated Raman transitions. The basic principle of an atomic interferometer gyroscope is to utilize atomic matter waves for interference. During this interference process, the Coriolis force exerted on the atoms produces a rotational phase shift through the Sagnac effect. Measuring this phase shift enables the measurement of angular velocity. This process typically involves physical processes such as atom preparation, cooling, ejection, state selection, interference, and detection. To improve the measurement sensitivity of atomic gyroscopes, a common experimental approach is to increase the interference cycle time. This method increases the distance between the Raman beams in the interferometer gyroscope, resulting in an excessively large system size. It also places higher demands on the parallelism of the effective wave vectors between the Raman beams, making it difficult to align the effective wave vectors between the Raman beams. Summary of the Invention

[0003] Based on the above description, the present invention provides a Raman light state selection interference device for an atomic interferometer gyroscope to solve the technical problems in the prior art that the atomic interferometer gyroscope device is large in size and the effective wave vectors between Raman lights are difficult to adjust.

[0004] The technical solution of the present invention to solve the above technical problems is as follows:

[0005] A Raman light state selection interference device for an atomic interference gyroscope comprises a Raman state selection light output element, a triangular reflection prism group, a polarization beam splitter prism, a vacuum cavity, a first 1 / 4 wave plate, a plane reflection mirror, a Raman interference light output element and a second 1 / 4 wave plate.

[0006] The Raman selected light output element is used to output Raman selected light with a predetermined polarization direction downward; the triangular reflecting prism group includes three triangular reflecting prisms that reflect in sequence, and the Raman selected light is reflected in sequence by the triangular reflecting prism group, and then completely passes through the polarization beam splitter prism horizontally and is emitted to the vertically arranged vacuum cavity; the first 1 / 4 wave plate and the plane reflecting mirror are arranged on one side of the vacuum cavity, and are used to make the Raman selected light that passes through the vacuum cavity be reflected along the original light path and pass through the vacuum cavity again; the Raman selected light that passes through the vacuum cavity successively can undergo two-photon stimulated Raman transition with the atomic group ejected from the lower end of the vacuum cavity to the center of the Raman selected light beam;

[0007] The Raman interference light output element is used to output linearly polarized Raman interference light with a predetermined polarization direction downward; the linearly polarized Raman interference light is sequentially reflected by the triangular reflection prism group and then incident on the polarization beam splitter prism, and is divided into a first Raman interference light and a second Raman interference light with equal power and perpendicular polarization directions. The first Raman interference light is horizontally emitted toward the vacuum cavity, passes through the first 1 / 4 wave plate, and is reflected by the plane reflection mirror along the original light path and passes through the vacuum cavity again. The first Raman interference light that passes through the vacuum cavity successively can undergo two-photon stimulated Raman transition with the atomic group ejected to the center of the Raman interference light beam; the second Raman interference light is vertically emitted upward toward the fourth triangular reflection prism, passes through the second 1 / 4 wave plate, and is reflected by the plane reflection mirror along the original light path and passes through the vacuum cavity again.

[0008] Compared with the prior art, the technical solution of this application has the following beneficial technical effects:

[0009] 1. By using a polarization beam splitter to spatially split the Raman interference light, the two Raman interference lights share one Raman interference collimator, reducing the number of collimators;

[0010] 2. By using a triangular reflecting prism, the Raman selected light and the Raman interference light share a polarization beam splitter prism, which has a compact structure and saves space, and can effectively reduce the size of the atomic interferometer gyroscope device;

[0011] 3. By using a large flat mirror with a good surface shape to replace the traditional independent multiple mirrors, the problem of the atomic interferometer gyroscope being difficult to assemble and adjust due to the high requirement for the parallelism of the effective wave vector between the two Raman beams.

[0012] On the basis of the above technical solution, the present invention can also be improved as follows.

[0013] Furthermore, the Raman state selected light and the Raman interference light include light of two frequencies, and the frequency difference is equal to the difference between two ground state energy levels of the hyperfine energy levels of alkali metal atoms used in the atomic interference gyroscope.

[0014] Furthermore, the Raman state-selective light output element includes a Raman state-selective collimator and a first 1 / 2 wave plate. The input end of the Raman state-selective collimator is connected to the polarization-maintaining optical fiber, and the first 1 / 2 wave plate is arranged at the output end of the Raman state-selective collimator.

[0015] Furthermore, the Raman interference light output element includes a Raman interference collimator and a second 1 / 2 wave plate, and the second 1 / 2 wave plate is arranged at the output end of the Raman interference collimator.

[0016] Furthermore, the triangular reflecting prism group includes a first triangular reflecting prism, a second triangular reflecting prism, and a third triangular reflecting prism. The output ends of the Raman state selection collimator and the Raman interference collimator are both set corresponding to the reflecting surface of the first triangular reflecting prism. The first triangular reflecting prism and the second triangular reflecting prism are set at the same height and the reflecting surfaces are perpendicular to each other. The third triangular reflecting prism is located above the second triangular reflecting prism.

[0017] Furthermore, the transmission surfaces of the first half wave plate, the second half wave plate, the first quarter wave plate, the second quarter wave plate and the polarization beam splitter prism are all coated with anti-reflection films corresponding to the Raman light wavelength.

[0018] Furthermore, both surfaces of the plane reflector are coated with a high-reflection film corresponding to the Raman light wavelength, the surface accuracy of the reflective surface is less than λ / 10@632.8nm, and the parallelism of the two surfaces is less than 1".

[0019] Furthermore, the first Raman interference light and the second Raman interference light have equal power and orthogonal polarization directions, and their transmission directions in the vacuum cavity have a certain angle with the orthogonal direction of atomic motion to distinguish the same direction and the reverse direction transition spectral lines.

[0020] Furthermore, it also includes a purge light collimator, which is used to output a purge light with only one frequency, and the purge light is reflected by the fifth triangular reflection prism and then horizontally projected to the vacuum chamber, and the setting height of the fifth triangular reflection prism is located between the third triangular reflection prism and the fourth triangular reflection prism.

[0021] Furthermore, the alkali metal atomic wave source used in the device is any one of 133Cs, Rb, K, Na, and Ca. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic structural diagram of a Raman optical state-selective interferometry device for an atomic interferometer gyroscope provided in an embodiment of the present invention;

[0023] Figure 2 for Figure 1 Side view of;

[0024] Figure 3 Schematic diagram of the light path for state selection;

[0025] Figure 4 This is a schematic diagram of the purge light path;

[0026] Figure 5 Schematic diagram of the interference light path in the first stage;

[0027] Figure 6 Schematic diagram of the interference light path in the second stage. DETAILED DESCRIPTION

[0028] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0030] It will be understood that spatial relational terms such as "under", "beneath", "below", "under", "above", "above", etc., may be used herein to describe the relationship of an element or feature shown in the figures to other elements or features. It will be understood that in addition to the orientations shown in the figures, spatial relational terms also include different orientations of the device in use and operation. For example, if the device in the drawings is turned over, the element or feature described as "under the other elements" or "under it" or "below it" will be oriented as "on" the other elements or features. Therefore, the exemplary terms "under" and "under" may include both upper and lower orientations. In addition, the device may also include alternative orientations (e.g., rotated 90° or other orientations), and the spatial descriptors used herein are interpreted accordingly.

[0031] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intermediate element. In the following embodiments, "connection" should be understood as "electrical connection", "communication connection", etc., if the connected circuits, modules, units, etc. can transmit electrical signals or data to each other.

[0032] When used herein, the singular forms "a", "an", and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

[0033] The present application provides a Raman optical state selection interferometer device for an atomic interferometer gyroscope. Figure 1 and Figure 2As shown, where the xy directions are two perpendicular directions on the horizontal plane and the z direction is the vertical direction, the device includes a Raman state selection collimator 1, a first 1 / 2 wave plate 2, a first triangular reflection prism 3, a second triangular reflection prism 4, a third triangular reflection prism 5, a polarization beam splitter prism 6, a vacuum cavity 7, a first 1 / 4 wave plate 8, a plane reflection mirror 9, a purge light collimator 10, a fifth triangular reflection prism 11, a Raman interference collimator 12, a second 1 / 2 wave plate 13, a fourth triangular reflection prism 14, a second 1 / 4 wave plate 15 and an atomic group 16.

[0034] Among them, the Raman selected collimator 1 and the first 1 / 2 wave plate 2 constitute a Raman selected light output element, which is used to output Raman selected light with a predetermined polarization direction downward; specifically, in this embodiment, the alkali metal atom wave source used is 133Cs, the wavelength of the Raman selected light and the interference light is around 852nm, and the diameter of the first 1 / 2 wave plate 2 is 12.8mm.

[0035] like Figure 3 As shown, the Raman selected light transmitted by the polarization-maintaining optical fiber first passes through the Raman selected collimator 1 and is expanded into a collimated light beam with a spot Gaussian diameter of 13.5 mm. The Raman selected light and the Raman interference light recorded subsequently both contain light of two frequencies, and the frequency difference is equal to the difference between the two ground state energy levels of the hyperfine energy levels of alkali metal atoms used in the atomic interferometer gyroscope. In this embodiment, the Raman selected light and the Raman interference light are linearly polarized outputs, which include a pair of lasers with similar wavelengths and a frequency difference of 9.19263 GHz.

[0036] The first triangular reflecting prism 3, the second triangular reflecting prism 4 and the third triangular reflecting prism 5 form three triangular reflecting prism groups that reflect in sequence, which are used to change the transmission direction of Raman selected light. In the present application, the Raman selected light is reflected in sequence by the triangular reflecting prism group and then passes completely through the polarizing beam splitter prism 6 horizontally and is emitted toward the vertically arranged vacuum cavity 7. The size of the polarizing beam splitter prism 6 is 50.8mm×50.8mm×50.8mm.

[0037] The first 1 / 4 wave plate 8 and the plane mirror 9 are arranged on one side of the vacuum cavity 7, and are used to make the Raman selected light passing through the vacuum cavity 7 be reflected along the original light path and pass through the vacuum cavity 7 again, wherein the Raman selected light passing through the vacuum cavity 7 in chronological order can undergo two-photon stimulated Raman transition with the atomic group ejected from the lower end of the vacuum cavity 7 to the center of the Raman selected light beam, thereby completing the preparation of the magnetically insensitive state (mF=0) of the atomic group 16.

[0038] Specifically, the first quarter wave plate 8 has a diameter of 50.8 mm; the plane reflector has a surface shape of λ / 10@632.8 nm, and the parallelism of the two surfaces is less than 1″.

[0039] Combine Figure 4 As shown, the purge light collimator 10 is used to output a purge light with only one frequency. The purge light is reflected by the fifth triangular reflection prism 11 and then horizontally emitted to the vacuum chamber 7. The setting height of the fifth triangular reflection prism 11 is located between the third triangular reflection prism 5 and the fourth triangular reflection prism 14.

[0040] After a predetermined time, the purge light collimator 10 outputs a purge light with a Gaussian diameter of 10.8 mm after collimation and expansion, and the purge light has a frequency of F=4-F'=5; the purge light passes through the fifth triangular reflecting prism 11 and is incident on the vacuum cavity 7, where it interacts with the atomic cluster 16 ejected to the center of the purge light at this moment by a single photon, blowing away the atoms in the magnetically sensitive state (mF≠0), completing the preparation of pure atoms in the magnetically insensitive state (mF=0), i.e., realizing the Raman state selection process.

[0041] The Raman interference collimator 12 and the second 1 / 2 wave plate b13 constitute the Raman interference light output element, which is used to output linearly polarized Raman interference light with a predetermined polarization direction downward.

[0042] The linearly polarized Raman interference light is reflected in sequence by the triangular reflecting prism group and then incident on the polarization splitting prism 6, and is divided into a first Raman interference light p and a second Raman interference light s with equal power and perpendicular polarization directions, wherein the first Raman interference light p is horizontally emitted toward the vacuum cavity 7, passes through the first 1 / 4 wave plate 8, and is reflected by the plane reflecting mirror 9 along the original optical path and passes through the vacuum cavity 7 again. The first Raman interference light p that passes through the vacuum cavity successively can undergo two-photon stimulated Raman transition with the atomic group 16 ejected to the center of the Raman interference beam; the second Raman interference light s is vertically emitted upward toward the fourth triangular reflecting prism 14, passes through the second 1 / 4 wave plate 13, and is reflected by the plane reflecting mirror 9 along the original optical path and passes through the vacuum cavity again.

[0043] In this embodiment, the output ends of the Raman state selection collimator 1 and the Raman interference collimator 12 are both set corresponding to the reflecting surface of the first triangular reflecting prism 3, the first triangular reflecting prism 3 and the second triangular reflecting prism 4 are set at the same height and the reflecting surfaces are perpendicular to each other, and the third triangular reflecting prism 5 is located above the second triangular reflecting prism 2.

[0044] Specifically, after completing the Raman state selection process, combined with Figure 5 and Figure 6As shown, the atomic cluster 16 continues to be thrown upward, and after a certain interval of time t2, the first stage of interference is carried out. At this time, the Raman interference collimator 12 outputs linearly polarized Raman interference light after collimation and expansion, and the Gaussian diameter of the light spot is 35.6 mm. The Raman interference light has the same frequency component as the Raman selected state light; the Raman interference light changes its polarization direction through the second 1 / 2 wave plate 13, and is reflected by the first triangular reflection prism 3, the second triangular reflection prism 4 and the third triangular reflection prism 5 in sequence and then enters the polarization splitter prism 6 to form two beams of Raman interference light with perpendicular polarizations: the first Raman interference light p and the second Raman interference light s. The second 1 / 2 wave plate 13 makes the power of the first Raman interference light p and the second Raman interference light s equal. Specifically, the power of the first Raman interference light p and the second Raman interference light s are equal, and the polarization directions are orthogonal. The transmission direction in the vacuum cavity 7 has a certain angle with the orthogonal direction of the movement of the atomic cluster, which is used to distinguish between the same direction and the reverse direction transition spectral lines.

[0045] The first Raman interference light p is transmitted through the polarization splitter prism 6, passes through the vacuum cavity 7, passes through the first 1 / 4 wave plate 8 and the plane mirror 9, and then passes through the vacuum cavity 7 again, and undergoes a two-photon stimulated Raman transition interaction with the atomic group 16 that is now ejected to the center of the first Raman interference light p beam.

[0046] The second Raman interference light s is reflected by the polarization beam splitter prism 6 to the fourth triangular reflecting prism 14 of 50.8 mm × 50.8 mm, passes through the vacuum cavity 7 after being reflected by the fourth triangular reflecting prism 14, passes through the second 1 / 4 wave plate 13, and then is reflected by the plane reflecting mirror 9 along the original optical path to pass through the vacuum cavity again; after a certain time t3, the Raman interference collimator 12 outputs the linearly polarized Raman interference light after collimation and expansion again, and the above process is repeated. The second Raman interference light s is reflected by the polarization beam splitter prism 6 to the fourth triangular reflecting prism 14, passes through the vacuum cavity 7 after being reflected by the fourth triangular reflecting prism 14, passes through the second 1 / 4 wave plate 13, and then is reflected by the plane reflecting mirror 9 along the original optical path to pass through the vacuum cavity again, and undergoes a two-photon stimulated Raman transition interaction with the atomic group that is now ejected to the center of the Raman interference light beam s.

[0047] The atomic cluster 16 continues to rise, and after reaching the top, the atomic cluster speed is 0, and it falls under the action of gravity. After the first interaction with the s light, after 2 times the t3 time, the first stage of interference is carried out. At this time, the Raman interference collimator 12 outputs the linearly polarized Raman interference light after collimation and expansion again, and repeats the above process. The second Raman interference light s is reflected by the polarization beam splitter prism 6 to the fourth triangular reflection prism d14, and after being reflected by the fourth triangular reflection prism d14, it passes through the vacuum cavity 7, passes through the second 1 / 4 wave plate 15, and is reflected by the plane reflector 9 along the original light path and passes through the vacuum cavity again, and is ejected at this moment. The atomic cluster at the center of the Raman interference s beam undergoes a two-photon stimulated Raman transition, and the atomic cluster 16 continues to fall. After t3 time, the Raman interference collimator 12 outputs the linearly polarized Raman interference light after collimation and expansion again, and repeats the above process. The first Raman interference light p is transmitted through the second 1 / 4 wave plate 15 of the vacuum cavity through the polarization splitter prism 6 and then passes through the vacuum cavity 7 again through the plane mirror 9, and undergoes a two-photon stimulated Raman transition with the atomic cluster 16 that now falls to the center of the Raman interference p beam, so that the two interference paths of the internal state atoms are closed, forming Raman interference.

[0048] Preferably, the transmission surfaces of the first half wave plate 2, the second half wave plate 13, the first quarter wave plate 8, the second quarter wave plate 15 and the polarization beam splitter prism 6 are coated with an antireflection film corresponding to the Raman light wavelength, i.e., an 852 nm film.

[0049] The Raman beam has a certain angle with the orthogonal direction of the atomic group motion in space, ensuring the separation of the opposite and same-direction transition spectral lines. The parallelism of the plane reflector 9 is less than 1", and the surface shape is λ / 10@632nm. Therefore, the effective wave vector direction parallelism of the Raman interference light at different times is less than 5μrad, meeting the high requirement of effective wave vector parallelism between the two spatially separated Raman light beams in the vacuum cavity 7. It can form an interference loop with a certain area and is sensitive to the angular velocity of rotation.

[0050] In the present invention, alkali metal atoms such as Rb, K, Na, and Ca may also be used as atomic sources in the atomic interferometer gyroscope, and the embodiment of the present invention does not impose any limitation on this.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A Raman optical state selection interferometer device for atomic interferometer gyroscope, characterized in that: It includes a Raman state selection light output element, a triangular reflection prism group, a polarization beam splitter prism, a vacuum cavity, a first 1 / 4 wave plate, a plane reflection mirror, a Raman interference light output element and a second 1 / 4 wave plate; The Raman selected light output element is used to output Raman selected light with a predetermined polarization direction downward; the triangular reflecting prism group includes three triangular reflecting prisms that reflect in sequence, and the Raman selected light is reflected in sequence by the triangular reflecting prism group, and then completely passes through the polarization beam splitter prism horizontally and is emitted to the vertically arranged vacuum cavity; the first 1 / 4 wave plate and the plane reflecting mirror are arranged on one side of the vacuum cavity, and are used to make the Raman selected light that passes through the vacuum cavity be reflected along the original light path and pass through the vacuum cavity again; the Raman selected light that passes through the vacuum cavity successively can undergo two-photon stimulated Raman transition with the atomic group ejected from the lower end of the vacuum cavity to the center of the Raman selected light beam; The Raman interference light output element is used to output linearly polarized Raman interference light with a predetermined polarization direction downward; the linearly polarized Raman interference light is sequentially reflected by the triangular reflection prism group and then incident on the polarization beam splitter prism, and is divided into a first Raman interference light and a second Raman interference light with equal power and perpendicular polarization directions. The first Raman interference light is horizontally emitted toward the vacuum cavity, passes through the first 1 / 4 wave plate, and is reflected by the plane reflection mirror along the original light path and passes through the vacuum cavity again. The first Raman interference light that passes through the vacuum cavity successively can undergo two-photon stimulated Raman transition with the atomic group ejected to the center of the Raman interference light beam; the second Raman interference light is vertically emitted upward toward the fourth triangular reflection prism, passes through the second 1 / 4 wave plate, and is reflected by the plane reflection mirror along the original light path and passes through the vacuum cavity again.

2. The Raman optical state selection interferometer device for atomic interferometer gyroscope according to claim 1, characterized in that: The Raman state selected light and the Raman interference light contain light of two frequencies, and the frequency difference is equal to the difference between two ground state energy levels of the hyperfine energy level of the alkali metal atoms used in the atomic interference gyroscope.

3. The Raman optical state selection interferometer device for atomic interferometer gyroscope according to claim 1, characterized in that: The Raman state-selective light output element includes a Raman state-selective collimator and a first 1 / 2 wave plate. The input end of the Raman state-selective collimator is connected to the polarization-maintaining optical fiber, and the first 1 / 2 wave plate is arranged at the output end of the Raman state-selective collimator.

4. The Raman optical state selection interferometer device for atomic interferometer gyroscope according to claim 3, characterized in that: The Raman interference light output element includes a Raman interference collimator and a second 1 / 2 wave plate, and the second 1 / 2 wave plate is arranged at the output end of the Raman interference collimator.

5. The Raman optical state selection interferometer device for atomic interferometer gyroscope according to claim 4, characterized in that: The triangular reflecting prism group includes a first triangular reflecting prism, a second triangular reflecting prism, and a third triangular reflecting prism. The output ends of the Raman state selection collimator and the Raman interference collimator are both set corresponding to the reflecting surface of the first triangular reflecting prism. The first triangular reflecting prism and the second triangular reflecting prism are set at the same height and the reflecting surfaces are perpendicular to each other. The third triangular reflecting prism is located above the second triangular reflecting prism.

6. The Raman optical state selection interferometer device for atomic interferometer gyroscope according to claim 5, characterized in that: The transmission surfaces of the first 1 / 2 wave plate, the second 1 / 2 wave plate, the first 1 / 4 wave plate, the second 1 / 4 wave plate and the polarization beam splitter prism are all coated with anti-reflection films corresponding to the Raman light wavelength.

7. The Raman optical state selection interferometer device for atomic interferometer gyroscope according to claim 5, characterized in that: Both sides of the plane reflector are coated with a high-reflection film corresponding to the Raman light wavelength. The surface accuracy of the reflective surface is less than λ / 10@632.8nm, and the parallelism of the two surfaces is less than 1".

8. The Raman optical state selection interferometer device for atomic interferometer gyroscope according to claim 5, characterized in that: The first Raman interference light and the second Raman interference light have equal power and orthogonal polarization directions. Their transmission directions in the vacuum cavity have a certain angle with the orthogonal direction of atomic motion, which is used to distinguish the same-direction and reverse-direction transition spectral lines.

9. The Raman optical state selection interferometer device for atomic interferometer gyroscope according to claim 4, characterized in that: It also includes a purge light collimator, which is used to output a purge light with only one frequency. The purge light is reflected by a fifth triangular reflection prism and then horizontally emitted to the vacuum chamber. The setting height of the fifth triangular reflection prism is located between the third triangular reflection prism and the fourth triangular reflection prism.

10. The Raman optical state selection interferometer device for atomic interferometer gyroscope according to claim 1, characterized in that: The alkali metal atomic wave source used by the device is any one of 133Cs, Rb, K, Na, and Ca.

Images