Multi-channel and transportable optical reference cavity and ultra-stable optical reference cavity system

Abstract

The invention provides a transportable multi-channel optical reference cavity and an ultra-stable optical reference cavity system. The transportable multi-channel optical reference cavity comprises a cavity body made of the same monocrystalline silicon material and a plurality of pairs of cavity mirrors, wherein the cavity body is of a cylindrical structure; the axial direction of the cavity is the [111] crystal orientation of monocrystalline silicon; a plurality of uniformly spaced light through holes are formed in the cavity along the radial direction; the multiple pairs of cavity mirrors are installed on the cavity, the multiple pairs of cavity mirrors are in one-to-one correspondence with the multiple light through holes, each pair of cavity mirrors is parallel to each other and symmetrically arranged at the two axial ends of the corresponding light through hole in the direction orthogonal to the axis of the corresponding light through hole, and a laser transmission channel is formed between each pair of cavity mirrors; wherein the cavity body and the plurality of pairs of cavity mirrors are configured to enable the transportable reference cavity to have a central symmetry structure so as to keep the stability of the mechanical performance and the thermal performance of the cavity body of the whole optical reference cavity.

Description

Technical Field

[0001] The present invention relates to the field of optical reference cavities, and particularly to a multi-channel and portable optical reference cavity and an ultra-stable optical reference cavity system. Background Art

[0002] Optical clocks have higher frequency uncertainty and stability compared to microwave clocks, and thus will become the next-generation time-frequency standard to provide a new detection method for ultra-high-precision basic physical tests. As the frequency locking reference of a laser, an ultra-stable cavity is the core device for preparing ultra-stable lasers and an essential key component for preparing optical clocks at the current technical level. The stability of the ultra-stable cavity directly determines the short-term stability of the optical clock frequency. The core device of the ultra-stable cavity is the optical reference cavity, and the other components mainly include devices such as support vibration isolation, temperature control, and vacuum designed for supporting the optical reference cavity.

[0003] There are two conventional cavity materials for optical reference cavities: ultra-low thermal expansion rate glass (ULE) that works at room temperature, and single-crystalline silicon that works at low temperatures. The stability limit of ultra-stable lasers depends on the thermal noise level of the optical reference cavity. The lower the working temperature, the lower its thermal noise limit. Among the reported ultra-stable laser systems, the laser with the highest stability index is locked on a single-crystalline silicon optical reference cavity with a working temperature of 124K, and its frequency stability is better than 5E-17 per second. There have been many research results on ULE optical reference cavities, while the related technologies of emerging single-crystalline silicon optical reference cavities are gradually being explored and developed.

[0004] To ensure the frequency stability of ultra-stable lasers, the ultra-stable cavity must have very low vibration sensitivity. The vibration sensitivity mainly depends on the shape of the optical reference cavity and the cavity support method. However, the reported single-crystalline silicon ultra-stable cavity support designs are only suitable for use in laboratories and do not consider the handling requirements. In recent years, as an extremely high-precision time-frequency source, optical clocks have a wide range of application scenarios. More and more work requires optical clocks to be used under portable conditions in order to realize the application of optical reference cavities in optical clocks in a wide area. This requires that the optical reference cavity has both low vibration sensitivity and a stable support structure that can withstand a certain amount of vibration without displacement or damage.

[0005] To meet these requirements, several portable optical reference cavity schemes have been proposed, but the cavities in these schemes are all based on ULE materials. Although single-crystalline silicon materials have better thermal noise levels, due to the anisotropic characteristics of single-crystalline silicon materials, it is difficult to meet the portable requirements compared to glass cavities. Summary of the Invention

[0006] In view of this, the present invention provides a multi-channel and portable optical reference cavity and an ultra-stable optical reference cavity system.

[0007] As a first aspect of the present invention, there is provided a multi-channel and portable optical reference cavity, which includes a cavity and multiple pairs of cavity mirrors made of the same single-crystal silicon material:

[0008] The cavity has a cylindrical structure; the axial direction of the cavity is the

[111] crystal orientation of the single-crystal silicon; multiple uniformly spaced light-passing holes are formed in the cavity along the radial direction, the light-passing holes penetrate through both radial ends of the cavity, and the axes of the multiple light-passing holes intersect at the axis of the cavity;

[0009] The multiple pairs of cavity mirrors are mounted on the cavity, and the multiple pairs of cavity mirrors correspond to the multiple light-passing holes one by one. Each pair of cavity mirrors is parallel to each other and is symmetrically arranged at both axial ends of the corresponding light-passing hole in a direction orthogonal to the axis of the corresponding light-passing hole. A laser transmission channel is formed between each pair of cavity mirrors;

[0010] Wherein, the cavity and the multiple pairs of cavity mirrors are configured to make the optical reference cavity have a centrosymmetric structure to maintain the stability of the mechanical properties and thermal properties of the optical reference cavity.

[0011] According to an embodiment of the present invention, a first part and a second part are formed on the side surface of the cavity at intervals. The projection of the first part in a preset direction is a straight line, and the projection of the second part in the preset direction is an arc; the preset direction is a direction orthogonal to the bottom surface of the cavity, and the light-passing holes are formed on a part of the first part, and one cavity mirror is mounted on the mounting surface of each first part.

[0012] According to an embodiment of the present invention, both the number of the first parts and the number of the second parts are six.

[0013] According to an embodiment of the present invention, the cavity mirrors are mounted on the cavity by means of optical cementing.

[0014] According to an embodiment of the present invention, air holes are further formed on the cavity. The air holes have the same axis as the cavity and penetrate through both ends in the axial direction of the cavity.

[0015] According to an embodiment of the present invention, both ends of the cavity are respectively configured to have connecting parts with a frustum-shaped structure, and the axes of the connecting parts coincide with the axis of the cavity.

[0016] According to an embodiment of the present invention, a plurality of support points are uniformly and spacedly arranged along the circumferential direction on the slope surface of the frustum-shaped structure of the connecting part, and the projection of one of the support points in the preset direction is located in the [2 - 1 - 1] crystal orientation of the single-crystal silicon.

[0017] According to an embodiment of the present invention, the cavity mirrors are mounted on the cavity by means of optical cementing.

[0018] As a second aspect of the present invention, there is also provided an ultra-stable optical reference cavity system, which includes:

[0019] The above-mentioned optical reference cavity; and a support frame, sleeved on the outer periphery of the optical reference cavity, and the position of the optical reference cavity is restricted by applying pressure to the support points.

[0020] According to an embodiment of the present invention, the support frame forms a plurality of through holes in the circumferential direction, and the through holes are adapted to allow an external laser signal to pass through the through holes and enter the cavity from the light passing holes.

[0021] According to an embodiment of the present invention, the frequency stability of the optical reference cavity is mainly determined by the thermal noise level and the vibration sensitivity. The thermal noise level is mainly caused by the atomic and molecular Brownian motion of the cavity body, the cavity mirrors and the reflective film plated on the cavity mirrors, and the vibration sensitivity is related to the deformation of the cavity under acceleration.

[0022] According to an embodiment of the present invention, the optical reference cavity made of single-crystalline silicon material can significantly reduce the thermal noise level compared with the ULE optical reference cavity. In addition, since the cavity body has a cylindrical structure, the axial direction of the cavity body is designed along the

[111] crystal direction of the single-crystalline silicon, so that the cavity body shows low sensitivity to vibration acceleration in any direction.

[0023] According to an embodiment of the present invention, the (111) crystal plane of single-crystalline silicon has a higher elastic modulus and stronger anti-deformation ability. The cavity mirror is set to be made of the (111) crystal plane of single-crystalline silicon, and also has a lower thermal noise level and can reduce the mirror surface distortion caused by vibration. The cavity mirror and the cavity body are processed from the same piece of single-crystalline silicon material, which can reduce the influence of the material mechanical properties and thermal properties deviation, avoid the splicing stress and performance mismatch, and thus further reduce the vibration sensitivity.

[0024] The relocatable reference cavity is set to have a centrosymmetric structure, which can make the stress distribution more uniform when the cavity body is subjected to external vibration, and avoid local stress concentration resulting in the deformation of the cavity body. The geometric symmetry of the cavity body makes the first-order relationship between the cavity length change and the vibration acceleration automatically cancel out (that is, the first-order sensitivity approaches zero).

[0025] The single-crystalline silicon optical reference cavity of the embodiment of the present invention simultaneously has a low thermal noise level and a low vibration sensitivity, successfully realizes the portability of the single-crystalline silicon optical reference cavity, and breaks through the bottleneck that the traditional single-crystalline silicon cavity body is difficult to be practically applied due to the anisotropic characteristics. This technical breakthrough enables the optical reference cavity based on single-crystalline silicon to be practically applied to the optical clock system, providing key technical support for improving the frequency stability and measurement accuracy of the optical clock. Description of the Drawings

[0026] Through the following description of the embodiments of the present invention with reference to the accompanying drawings, the above and other objects, features, and advantages of the present invention will become more apparent. In the drawings:

[0027] Figure 1 A perspective view of a multi-channel portable reference cavity provided according to an embodiment of the present invention is shown.

[0028] Figure 2 A perspective view of a multi-channel portable reference cavity provided according to another embodiment of the present invention is shown.

[0029] Figure 3 A perspective view of an ultra-stable optical reference cavity system provided according to an embodiment of the present invention is shown.

[0030] Description of reference numerals:

[0031] 1 Optical reference cavity

[0032] 11 Cavity

[0033] 111 Light passing hole

[0034] 112 First part

[0035] 113 Second part

[0036] 114 Ventilation hole

[0037] 115 Connection part

[0038] 116 Support point

[0039] 12 Cavity mirror

[0040] 2 Support frame

[0041] 21 First adapter ring

[0042] 211 Fixed groove

[0043] 22 Second adapter ring

[0044] 23 Through hole Detailed implementation manners

[0045] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to specific embodiments and the accompanying drawings.

[0046] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "including", "comprising", etc. used herein indicate the presence of the described features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0047] All terms used herein, including technical and scientific terms, have the meanings commonly understood by those of ordinary skill in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0048] In cases where expressions similar to "at least one of A, B, and C, etc." are used, generally, it should be interpreted according to the meaning commonly understood by those of ordinary skill in the art. For example, a "system having at least one of A, B, and C" should include, but not be limited to, a system having only A, only B, only C, having A and B, having A and C, having B and C, and / or having A, B, and C, etc. In cases where expressions similar to "at least one of A, B, or C, etc." are used, generally, it should be interpreted according to the meaning commonly understood by those of ordinary skill in the art. For example, a "system having at least one of A, B, or C" should include, but not be limited to, a system having only A, only B, only C, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.

[0049] It should also be noted that the directional terms mentioned in the embodiments, such as "up", "down", "front", "back", "left", "right", etc., are only references to the directions in the accompanying drawings and are not used to limit the protection scope of the present invention. Throughout the accompanying drawings, the same elements are represented by the same or similar reference numerals. When it may cause confusion in the understanding of the present invention, conventional structures or configurations will be omitted.

[0050] Figure 1 A perspective view of a multi-channel portable reference cavity provided according to an embodiment of the present invention is shown.

[0051] Figure 2 A perspective view of a multi-channel portable reference cavity provided according to another embodiment of the present invention is shown.

[0052] As Figure 1 to Figure 2 shown, the multi-channel portable reference cavity 1 includes: a cavity 11 made of the same single-crystalline silicon material and multiple pairs of cavity mirrors 12.

[0053] The cavity 11 is generally in a cylindrical structure; the axial direction of the cavity 11 is the

[111] crystal direction of the single-crystalline silicon; multiple uniformly spaced light-passing holes 111 are formed in the cavity 11 along the circumferential direction. The light-passing holes 111 penetrate through the radial two ends of the cavity 11, and the axes of the multiple light-passing holes 111 intersect at the axis of the cavity 11. The multiple pairs of cavity mirrors 12 are installed on the cavity 11 and correspond to the multiple light-passing holes one by one. Each pair of cavity mirrors is parallel to each other and is symmetrically arranged at the axial two ends of the corresponding light-passing hole along the direction orthogonal to the axis of the corresponding light-passing hole, and a laser transmission channel is formed between each pair of cavity mirrors 12.

[0054] Among them, the cavity 11 and multiple pairs of cavity mirrors 12 are configured to make the optical reference cavity 1 a centrosymmetric structure to maintain the stability of the mechanical and thermal properties of the optical reference cavity.

[0055] According to an embodiment of the present invention, the frequency stability of the optical reference cavity is mainly determined by the thermal noise level and vibration sensitivity. The thermal noise level is mainly caused by the atomic and molecular Brownian motion of the cavity 11, the cavity mirrors 12, and the reflective film plated on the cavity mirrors 12, and the vibration sensitivity is related to the deformation of the cavity under acceleration.

[0056] According to an embodiment of the present invention, since the thermal noise level of the optical reference cavity 1 is mainly caused by the atomic and molecular Brownian motion of the cavity 11, the cavity mirrors 12, and the reflective film plated on the cavity mirrors 12, the thermal noise level is proportional to the operating temperature of the cavity. The lower the operating temperature, the lower the corresponding thermal noise. The ideal operating temperature of the optical reference cavity made of ULE material (ULE optical reference cavity) is room temperature, while the single-crystalline silicon optical reference cavity has multiple ideal low-temperature operating temperature points, including around 124K, 17K, and 4K. Therefore, compared with the optical reference cavity made of ultra-low thermal expansion rate glass, the optical reference cavity made of single-crystalline silicon material can significantly reduce the thermal noise level relative to the ULE optical reference cavity.

[0057] According to an embodiment of the present invention, the silicon atoms in the

[111] crystal orientation of single-crystalline silicon are closely arranged and have a small thermal vibration amplitude. Since the cavity 11 is generally cylindrical in structure, designing the axial direction of the cavity 11 along the

[111] crystal orientation of single-crystalline silicon can make the elastic modulus and thermal expansion coefficient of the cavity 11 consistent in all directions within the radial plane of the cavity 11, so that the cavity 11 shows low sensitivity to vibration acceleration in any direction.

[0058] According to an embodiment of the present invention, the (111) crystal plane of single-crystalline silicon has a higher elastic modulus and stronger anti-deformation ability. The cavity mirror 12 is made of the (111) crystal plane of single-crystalline silicon, also having a low thermal noise level, which can reduce the mirror surface distortion caused by vibration. The cavity mirror 12 and the cavity are processed from the same single-crystalline silicon material, which can reduce the influence of the deviation of the mechanical and thermal properties of the material, avoid splicing stress and performance mismatch, and thus further reduce the vibration sensitivity.

[0059] Setting the multi-channel optical reference cavity as a centrosymmetric structure can make the stress distribution in the cavity more uniform when the cavity is subjected to external vibration, avoiding local stress concentration and resulting in deformation of the cavity. The geometric symmetry of the cavity makes the first-order relationship between the change in cavity length (i.e., the length of the channel) and vibration acceleration automatically cancel out (i.e., the first-order sensitivity approaches zero).

[0060] The optical reference cavity prepared from single-crystalline silicon material in the embodiments of the present invention has both a low thermal noise level and a low vibration sensitivity, successfully realizing the portability of the optical reference cavity made of single-crystalline silicon, and breaking through the bottleneck that the traditional single-crystalline silicon cavity is difficult to be practically applied due to its anisotropic characteristics. This technological breakthrough enables the optical reference cavity based on single-crystalline silicon material to be practically applied to the optical clock system, providing key technical support for improving the frequency stability and measurement accuracy of the optical clock. The optical reference cavity in the embodiments of the present invention can lock multiple optical clocks simultaneously and serve multiple optical clocks at the same time.

[0061] According to an embodiment of the present invention, the first part 112 and the second part 113 are arranged at intervals on the side surface of the cavity 11. The projection of the first part 112 in the preset direction is a straight line, and the projection of the second part 113 in the preset direction is an arc; the preset direction is the direction orthogonal to the bottom surface of the cavity. A light passing hole is formed on a part of the first part, and a cavity mirror is installed on the installation surface of each first part.

[0062] According to an embodiment of the present invention, the projection of the first part 112 is a straight line, that is, the first part 112 is used to provide a stable support surface, which is convenient for processing and installing the cavity mirror. The projection of the second part 113 is an arc (that is, the second part is a curved surface structure), which can enhance the bending stiffness of the side surface, disperse external stress, and reduce local deformation caused by vibration.

[0063] According to an embodiment of the present invention, the preparation process of the cavity 11 includes: first, a cylindrical initial structure is prepared from single-crystalline silicon material, and the axis of the initial structure is the

[111] crystal orientation of the single-crystalline silicon. Then, six planes are cut on the side surface of the initial structure, and the six planes are the installation surfaces of three pairs of cavity mirrors respectively.

[0064] According to an embodiment of the present invention, the number of the first parts 112 and the number of the second parts 113 are both six, the number of the light passing holes 111 is 3, and the included angle between two adjacent light passing holes is 60°. According to an embodiment of the present invention, if there are too many light passing holes 111, the mechanical strength of the cavity 11 will decrease, and the thermal stress distribution will be uneven in the low-temperature environment, affecting the long-term stability of the cavity 11. When the number of the light passing holes is 3 and the number of the first parts 112 and the number of the second parts 113 are both set to six, the vibration stability of the cavity is the highest.

[0065] According to an embodiment of the present invention, a ventilation hole 114 is further formed on the cavity 11. The ventilation hole 114 has the same axis as the cavity 1 and penetrates through both ends of the cavity 11 in the axial direction. The ventilation hole 114 is suitable for conducting the inside of the cavity 11 to the external environment so that the optical reference cavity 1 can be applicable to the vacuum environment.

[0066] According to an embodiment of the present invention, a reflecting film is plated on the cavity mirror, and the cavity mirror is mounted on the cavity 11 by means of optical cementing. Since the cavity mirror 12 and the cavity 11 are made of the same single-crystalline silicon material, the thermal expansion coefficients are perfectly matched after optical cementing, avoiding the drift of the cavity length (the length of any channel) caused by temperature fluctuations. In addition, the cementing interface is atomically bonded, without the risks of adhesive layer aging, volatilization or delamination, and the service life in a vacuum or low-temperature environment far exceeds that of the adhesive bonding solution. Again, the strength of the bonding interface is close to that of the single-crystalline silicon body, and micro-displacements are not easily generated during handling or vibration, which can ensure the parallelism of the cavity mirror 12.

[0067] According to an embodiment of the present invention, both ends of the cavity 11 are respectively configured to have connecting portions 115 with a frustum-shaped structure, and the axes of the connecting portions coincide with the axis of the cavity. Three support points 116 are evenly and spaced along the circumferential direction of the slope of the frustum-shaped structure of the connecting portion, and the projection of one of the support points 116 in a preset direction is located in the [2-1-1] crystal direction of the single-crystalline silicon. According to an embodiment of the present invention, the frustum-shaped structure is obtained by chamfering both ends of the initial structure. By applying pressure to the support points, the fixation and handling of the multi-channel optical reference cavity 1 can be achieved. By uniformly applying pressure to the cavity 11 through six support points, a statically determinate constraint is formed to offset the deformation of the cavity 11 caused by vibration in any direction, thereby ensuring that the change in the cavity length is insensitive to vibration. Making the projection of one of the support points accurately located in the [2-1-1] crystal direction of the single-crystalline silicon can make the position of the support point the position of the maximum elastic modulus of the single-crystalline silicon material. Utilizing the mechanical properties of this crystal direction to optimize the stress distribution, and evenly and spacedly arranging the three support points along the circumferential direction of the slope of the frustum-shaped structure, the cavity shows low sensitivity to vibration acceleration in any direction.

[0068] As the second aspect of the present invention, a super-stable optical reference cavity system is also provided.

[0069] Figure 3 The perspective view of the multi-channel portable reference cavity provided according to an embodiment of the present invention is shown.

[0070] As Figure 3 shown, the super-stable optical reference cavity system includes: a multi-channel portable reference cavity 1 and a support frame 2. The support frame 2 is sleeved on the outer periphery of the portable reference cavity 1. By applying pressure to the support points 116, the position of the reference cavity is restricted. According to an embodiment of the present invention, the support frame 2 of the multi-channel optical reference cavity can apply a pre-tightening force through support bolts located in six fixed slots to connect the entire cavity with the support frame, and then fix the support frame 2 to other mechanical structures to achieve the portability of the multi-channel optical reference cavity 1. The support frame uniformly applies pressure to the cavity through six support points to form a statically determinate constraint, offsetting the deformation of the cavity caused by vibration in any direction, thereby ensuring that the change in the cavity length is insensitive to vibration.

[0071] According to an embodiment of the present invention, the support frame 2 includes: two first adapter rings 21 and a second adapter ring 22 located in the middle of the two first adapter rings. The two first adapter rings 21 are respectively sleeved on the outer sides of the frustum-shaped structure connecting parts 111 at both ends of the cavity 11, and the second adapter ring 22 is sleeved on the outer side of the structure located between the connecting parts 115. The two first adapter rings 21 are respectively connected to the second adapter ring. The support frame 2 further includes two groups of support members. The first ends of the three support members in each group are installed on the first adapter ring 21. The second ends of each support member, which are opposite to the first ends, extend out from the first annular member 21 and the other ends abut against a support point 114 of the connecting part 111 to apply a pressure extending from the support point 116 towards the centroid direction of the cavity 11, so as to limit the position of the optical reference cavity 1 relative to the support frame 2.

[0072] According to an embodiment of the present invention, as Figure 3 shown, three fixing grooves 211 with internal threads are evenly distributed on the inner circumferential surface of the first adapter ring 21. The support member includes a bolt. One end of the bolt is screwed with the internal thread of the fixing groove 211, and the other end extends out of the fixing groove and contacts the support point 116 on the optical reference cavity 1. By adjusting the screwing depth of the bolt, an accurate pre-tightening force can be applied to the cavity 11, thereby realizing a reliable connection between the cavity 11 and the support frame 2. The support frame 2 can be further fixed to an external mechanism, thereby ensuring that the entire optical reference cavity system has portability.

[0073] According to an embodiment of the present invention, the support frame 2 forms a plurality of through holes 23 along the circumferential direction. The through holes 23 are adapted to allow an external laser signal to pass through and enter the cavity 11 from the light passing hole.

[0074] According to an embodiment of the present invention, when using the support device to carry the optical reference cavity, the vibration sensitivity of the optical reference cavity, that is, the relationship between the cavity length of the optical reference cavity and the vibration acceleration, depends on two factors: First, the deformation of the cavity under acceleration; Second, the deformation of the support frame under acceleration causes extrusion on the cavity, resulting in the deformation of the cavity 11. In this design, due to the geometric symmetry of the cavity and the geometric symmetry of the position and shape of the support points 116, at this time, the first-order relationship between the cavity length change of the cavity 11 and the vibration acceleration is automatically zero, minimizing the cavity length change caused by the deformation of the cavity 11 under acceleration. At the same time, the design of the six support points takes into account the fixed requirements of the linear displacement and rotation of the cavity, reducing the cavity length change caused by the relative deformation and displacement between the support conversion parts and the extrusion on the optical cavity, thereby ensuring that the cavity length change is insensitive to vibration. The cavity can be further fixed to other mechanical structures through the support frame, which can further reduce the influence of external vibration on the optical cavity, ensuring that the cavity can withstand strong vibration without displacement or damage, so that the multi-channel optical reference cavity 1 made of single-crystal silicon can also have portability.

[0075] According to an embodiment of the present invention, for the ultra-stable optical reference cavity system based on the above embodiment, through simulation by finite element analysis software, the vibration sensitivity in the ideal case is at the order of magnitude, which is similar to the designed value of the vibration sensitivity of the ULE material optical reference cavity reported. Moreover, the single-crystal silicon optical reference cavity in this design is not sensitive to the magnitude and direction of gravity, and is applicable to the ground gravity environment and the space microgravity environment.

[0076] The ultra-stable optical reference cavity system provided according to the embodiment of the present invention adopts a unique structure. Among them, while the single-crystal silicon optical reference cavity has a stable support structure, it also ensures a low vibration sensitivity of the order of E-12 / g, so that it can replace the conventional ULE optical reference cavity. At the same time, it can work at low temperature, greatly reducing the thermal noise level, and is expected to optimize the frequency stability limit of the ultra-stable laser from about 3E-16 to the level of 2E-17 (working temperature of 4K), solving the problem of limited frequency stability of the current mobile optical clock. The cavity of the present invention can also provide three optical channels, which can lock multiple optical clocks simultaneously and serve multiple optical clocks at the same time.

[0077] The embodiments of the present invention have been described above. However, these embodiments are only for illustrative purposes and not for limiting the scope of the present invention. Although the embodiments have been described separately above, this does not mean that the measures in each embodiment cannot be used advantageously in combination. The scope of the present invention is defined by the appended claims and their equivalents. Without departing from the scope of the present invention, those skilled in the art can make various substitutions and modifications, and these substitutions and modifications should all fall within the scope of the present invention.

Claims

1. A multi-channel and portable optical reference cavity, characterized in that Comprising: A cavity and multiple pairs of cavity mirrors made of the same single-crystalline silicon material; The cavity, having a cylindrical structure, with the axial direction of the cavity being the [111] crystal orientation of the single-crystalline silicon; the cavity is formed with multiple uniformly spaced light-passing holes along the radial direction, the light-passing holes penetrate through both radial ends of the cavity, and the axes of the multiple light-passing holes intersect at the axis of the cavity; The multiple pairs of cavity mirrors are installed on the cavity, and the multiple pairs of cavity mirrors correspond to the multiple light-passing holes one by one. Each pair of cavity mirrors is parallel to each other and symmetrically arranged at both axial ends of the corresponding light-passing hole along the direction orthogonal to the axis of the corresponding light-passing hole. A laser transmission channel is formed between each pair of cavity mirrors; Wherein, the cavity and the multiple pairs of cavity mirrors are configured to make the optical reference cavity have a centrosymmetric structure to maintain the stability of the mechanical properties and thermal properties of the optical reference cavity.

2. The optical reference cavity according to claim 1, wherein The side surface of the cavity forms a first part and a second part arranged at intervals. The projection of the first part in the preset direction is a straight line, and the projection of the second part in the preset direction is an arc; the preset direction is the direction orthogonal to the bottom surface of the cavity. The light-passing holes are formed on a part of the first part, and one cavity mirror is installed on the installation surface of each first part.

3. The optical reference cavity according to claim 2, wherein Both the number of the first parts and the number of the second parts are six.

4. The optical reference cavity according to claim 1, characterized in that, According to an embodiment of the present invention, the cavity mirrors are installed on the cavity by optical cementing.

5. The optical reference cavity according to claim 1, wherein The cavity is further formed with ventilation holes, and the ventilation holes have the same axis as the cavity and penetrate through both ends of the cavity along the axial direction.

6. The optical reference cavity according to claim 2, wherein Both ends of the cavity are respectively configured to have connecting parts with a frustum-shaped structure, and the axis of the connecting part coincides with the axis of the cavity.

7. The optical reference cavity according to claim 6, wherein The slope of the frustum-shaped structure of the connecting part is provided with multiple support points uniformly and at intervals along the circumferential direction, and the projection of one of the support points in the preset direction is located in the [2 - 1 - 1] crystal orientation of the single-crystalline silicon.

8. The optical reference cavity according to claim 1, characterized in that, The cavity mirrors are installed on the cavity by optical cementing.

9. A super-stable optical reference cavity system, characterized in that, Comprising: The optical reference cavity according to any one of claims 1 to 8; A support frame, sleeved on the outer periphery of the optical reference cavity, and the position of the optical reference cavity is restricted by applying pressure to the support points.

10. The ultra-stable optical reference cavity system according to claim 9, characterized in that, The support frame is formed with multiple through holes along the circumferential direction, and the through holes are adapted to allow an external laser signal to pass through the through holes and enter the cavity from the light-passing holes.

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