Portable Optical Reference Cavity and Ultra-Stable Cavity Device

Abstract

The present disclosure provides a movable optical reference cavity and an ultra-stable cavity device. The movable optical reference cavity is made of single-crystalline silicon to form a cavity body, and a light passing hole is formed in the cavity body. The axial direction of the light passing hole is parallel to the <111> crystal orientation of the single-crystalline silicon, and the cavity body is configured as a cylindrical structure, and the axis of the cavity body coincides with the axis of the light passing hole. The ultra-stable cavity device includes an optical reference cavity and a support frame. The support frame is sleeved outside the reference cavity and is configured to apply a pressure in the direction of the centroid of the cavity body to each support point to limit the position of the reference cavity; at the same time, the support points make the change in the length of the optical reference cavity insensitive to the vibration acceleration, so that the cavity length stability of the optical reference cavity can be maintained in a vibration environment.

Description

Technical Field

[0001] The present disclosure relates to the field of optical reference cavities, and more particularly, to a portable optical reference cavity and an ultra-stable cavity device. Background Art

[0002] The commonly used method for preparing ultra-stable lasers is to stabilize the laser frequency at the resonant frequency of the optical reference cavity in the ultra-stable cavity. Therefore, the optical reference cavity is a core device for preparing ultra-stable lasers.

[0003] The optical reference cavity body is mostly made of ultra-low thermal expansion glass (ULE) or single crystal silicon. Among them, the reported portable cavity bodies all use ULE materials. The stability limit of ultra-stable lasers depends on the thermal noise level of the optical reference cavity. The lower the operating temperature, the lower its thermal noise limit. Compared with ultra-low thermal expansion glass, the single crystal silicon cavity that can work at low temperatures has a better thermal noise level. However, due to the anisotropic characteristics of single crystals, its design difficulty is greater than that of ultra-low thermal expansion glass materials. And in order to reduce the influence of the vibration environment on the laser stability, the optical reference cavity must have a very low vibration sensitivity. Therefore, the shape and support method of the optical reference cavity in the ultra-stable cavity also need to be designed accordingly to provide an optical reference cavity with better frequency stability and portability. Summary of the Invention

[0004] To solve at least one of the above and other technical problems in the prior art, the present disclosure provides a portable optical reference cavity and an ultra-stable cavity device. The cavity body is made of single crystal silicon material, and light passing holes, air vent holes and support points are arranged according to the crystal orientation of the single crystal silicon, so that the optical reference cavity has better vibration sensitivity on the premise of having a better thermal noise level.

[0005] One aspect of the embodiments of the present disclosure provides a portable optical reference cavity, including a cavity body made of single crystal silicon material. A light passing hole is formed in the cavity body, and the axial direction of the light passing hole is parallel to the <111> crystal orientation of the single crystal silicon. And the cavity body is configured as a cylindrical structure, and the axis of the cavity body coincides with the axis of the light passing hole.

[0006] According to an embodiment of the present disclosure, both axial ends of the cavity body are respectively configured as connection parts suitable for being assembled with a support frame. The connection parts are configured as frustum-shaped structures, and the extending direction of the axis of the frustum-shaped structure coincides with the axis of the light passing hole.

[0007] According to an embodiment of the present disclosure, three support points are evenly spaced along the circumferential direction on the slope surface of the frustum-shaped structure of the connection part.

[0008] According to an embodiment of the present disclosure, the support points provided on the two connection parts are symmetric with respect to the radial direction of the cavity body.

[0009] According to an embodiment of the present disclosure, it further includes a vent hole, which is configured to extend in a direction orthogonal to the light passing hole and penetrate through the radial two ends of the cavity. The axis of the vent hole is parallel to the 01-1 crystal orientation of the single crystal silicon and passes through the centroid of the cavity.

[0010] According to an embodiment of the present disclosure, it further includes two cavity mirrors, the two cavity mirrors are parallel to each other, and are symmetrically arranged at the axial two ends of the light passing hole along a direction orthogonal to the axis of the light passing hole.

[0011] According to an embodiment of the present disclosure, the two cavity mirrors are mounted on the cavity by optical cementing.

[0012] Another aspect of the embodiments of the present disclosure provides an ultra-stable cavity device, including: an optical reference cavity; and a support frame, sleeved outside the reference cavity and configured to apply a pressure in the direction of the centroid of the cavity to each support point to limit the position of the reference cavity.

[0013] According to an embodiment of the present disclosure, the support frame includes: two first annular members, each of the first annular members is sleeved outside the connecting portion of the cavity; and two groups of support members, the first ends of the three support members in each group are mounted on the first annular member, and the second ends of each support member opposite to the first ends extend from the first annular member and abut against a support point of the connecting portion to apply a pressure extending from the support point in the direction of the centroid of the cavity, so that the position of the reference cavity relative to the support frame is limited and the optical reference cavity has low vibration sensitivity.

[0014] According to an embodiment of the present disclosure, three groove-shaped portions are evenly spaced along the circumferential direction on the inner surface of each first annular member, and internal threads are provided on the groove walls of the groove-shaped portions; the support member includes a bolt, the first end of the bolt is engaged with the internal thread, and the second end of the bolt extends from the groove-shaped portion and abuts against the support point.

[0015] For the portable optical reference cavity and ultra-stable cavity device provided by the present disclosure, the cavity made of single crystal silicon material has a better thermal noise level compared with the ultra-low thermal expansion rate glass material and is more suitable for working at low temperature. The cavity is configured as a cylindrical structure, the axis of the cylindrical structure and the axis of the through hole coincide and are parallel to the 111 crystal orientation of the single crystal silicon, and while meeting the requirements of the geometric symmetry of the cavity, it can achieve a vibration sensitivity similar to that of the optical reference cavity made of the known ultra-low thermal expansion rate glass material to meet the portable requirements of the optical reference cavity. Description of the Drawings

[0016] Figure 1Is a perspective view of an optical reference cavity according to an exemplary embodiment of the present disclosure;

[0017] Figure 2 Is Figure 1 A perspective view of the light passing hole and the ventilation hole part of the illustrated exemplary embodiment; and

[0018] Figure 3 Is a perspective view of an ultra-stable cavity device according to an exemplary embodiment of the present disclosure.

[0019] In the above-mentioned drawings, the meanings of the reference numerals are specifically as follows:

[0020] 1. Optical reference cavity;

[0021] 11. Cavity;

[0022] 111. Connecting part;

[0023] 112. Light passing hole;

[0024] 113. Ventilation hole;

[0025] 114. Support point;

[0026] 12. Mirror;

[0027] 2. Support frame;

[0028] 21. First annular member;

[0029] 211. Groove part; and

[0030] 22. Second annular member. Detailed implementation manners

[0031] To make the objectives, technical solutions and advantages of the present invention more clear and understandable, the following further describes the present invention in detail with reference to specific embodiments and the accompanying drawings.

[0032] The terms used herein are merely 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.

[0033] All terms used herein, including technical and scientific terms, have the meanings commonly understood by those skilled 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.

[0034] In the case of using expressions such as "at least one of A, B, and C, etc.", generally, it should be interpreted according to the meaning that those skilled in the art usually understand this expression. 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 the case of using expressions such as "at least one of A, B, or C, etc.", generally, it should be interpreted according to the meaning that those skilled in the art usually understand this expression. 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.

[0035] Figure 1 is a perspective view of an optical reference cavity according to a schematic embodiment of the present disclosure. Figure 2 is Figure 1 a perspective view of the light-passing hole and the ventilation hole part of the shown schematic embodiment.

[0036] The present disclosure provides an optical reference cavity 1, as Figure 1 and Figure 2 shown, including a cavity 11 made of single-crystalline silicon material. A light-passing hole 112 is formed in the cavity 11. The axial direction of the light-passing hole 112 is parallel to the 111 crystal orientation of the single-crystalline silicon. And the cavity 11 is configured to be a cylindrical structure, and the axis of the cavity 11 coincides with the axis of the light-passing hole 112.

[0037] In a schematic embodiment, the light-passing hole 112 is configured to penetrate along the axial direction of the cavity 11 (such as Figure 1 the up and down directions shown), so that the cavity 11 has better geometric symmetry.

[0038] In a schematic embodiment, the cavity 11 is made of a single piece of single-crystalline silicon. This can reduce the influence caused by the crystal orientation deviation of different single-crystalline silicon.

[0039] Since the thermal noise of the optical reference cavity 1 is mainly caused by the atomic and molecular Brownian motion of the cavity body 11, the cavity mirrors 12 and the coatings of the cavity mirrors 12, the level of thermal noise is proportional to the operating temperature of the optical reference cavity 1. The lower the operating temperature, the lower the corresponding thermal noise. In such an embodiment, the cavity body 11 made of single-crystalline silicon has multiple ideal low-temperature operating points (including but not limited to around 124K, 17K, and 4K (K represents Kelvin)) compared to ultra-low thermal expansion glass (ULE). This can significantly reduce the thermal noise level of the optical reference cavity 1. Moreover, by setting the extending direction of the light passing hole 112 to be parallel to the (111) crystal orientation of the single-crystalline silicon, the optical reference cavity 1 can still have a lower thermal noise level even when operating at the same temperature as the optical reference cavities 1 made of ultra-low thermal expansion glass (ULE) and fused quartz. In this way, the optical reference cavity 1 can achieve a vibration sensitivity of the order of 1E-16 at an operating temperature of 124K and a vibration sensitivity of the order of 2E-17 at an operating temperature of 4K. If the operating temperature is below 4K, since the thermal noise level is lower, the vibration sensitivity of the optical reference cavity 1 can be further improved.

[0040] According to an embodiment of the present disclosure, as Figure 1 and Figure 2 shown, both axial ends of the cavity body 11 are respectively configured as connection parts 111 adapted to be assembled with the support frame 2. The connection part 111 is configured as a frustum-shaped structure, and the extending direction of the axis of the frustum-shaped structure coincides with the axis of the light passing hole 112.

[0041] According to an embodiment of the present disclosure, as Figure 1 and Figure 2 shown, three support points 114 are evenly spaced along the circumferential direction on the slope surface of the frustum-shaped structure of the connection part 111.

[0042] According to an embodiment of the present disclosure, as Figure 1 and Figure 2 shown, the support points 114 provided on the two connection parts 111 are symmetric with respect to the radial direction of the cavity body 11.

[0043] In a schematic embodiment, the included angle formed by the lines connecting the three support points 114 to the centroid of the cavity body 11 is configured to be 120° when projected along the axial direction of the cavity body 11.

[0044] In such an embodiment, both the shape of the cavity body 11 and the positions of the support points 114 set according to the crystal orientation of the single-crystalline silicon have geometric symmetry. Thus, the cavity length of the cavity body 11 (characterized as, for example, Figure 2The first-order relationship between the change in the distance (the distance between the upper end face and the lower end of the cavity 11 shown) and the vibration acceleration automatically becomes zero, minimizing the change in the cavity length caused by the deformation of the cavity 11 under acceleration. At the same time, the design of the six support points 114 takes into account the linear displacement and rotational fixation requirements of the cavity 11, enabling the optical reference cavity 1 made of single-crystalline silicon material to be portable; reducing the change in the cavity length caused by the extrusion of the optical cavity due to the relative deformation and displacement between the cavity 11 and the support, thereby ensuring that the change in the cavity length is insensitive to vibration, so that the cavity 11 can be fixed to other mechanisms through the support frame 2, which is beneficial to further reducing the influence of external vibration on the optical reference cavity 1.

[0045] In a schematic embodiment, the connection line between the midpoint of the slope surface of the frustum-shaped structure formed by the connecting portion 111 and the centroid of the cavity 11 is perpendicular to the extending direction of the slope surface, so as to further improve the geometric symmetry of the cavity 11.

[0046] According to an embodiment of the present disclosure, as Figure 1 and Figure 2 shown, it further includes a vent hole 113, which is configured to extend in a direction orthogonal to the light passing hole 112 and penetrate through the radial two ends of the cavity 11, and the axis of the vent hole 113 is parallel to the (01-1) crystal orientation of the single-crystalline silicon and passes through the centroid of the cavity 11.

[0047] In such an implementation, the vent hole 113 is suitable for conducting the light passing hole 112 to the external environment, so that the optical reference cavity 1 can be applicable to a vacuum environment.

[0048] According to an embodiment of the present disclosure, as Figure 1 and Figure 2 shown, it further includes two cavity mirrors 12, the two cavity mirrors 12 are parallel to each other, and are symmetrically arranged at the axial two ends of the light passing hole 112 along a direction orthogonal to the axis of the light passing hole 112.

[0049] According to an embodiment of the present disclosure, as Figure 1 and Figure 2 shown, the two cavity mirrors 12 are mounted on the cavity 11 by means of optical cement.

[0050] In a schematic embodiment, the diameter of the cavity mirror 12 is larger than the diameter of the light passing hole 112.

[0051] Specifically, the two cavity mirrors 12 are respectively fixed and covered at one end of the axis of the light passing hole 112 by means of optical cement (such as Figure 2 the upper end and the lower end shown).

[0052] Furthermore, the centers of the two cavity mirrors 12 are both treated by depositing a high-reflectivity thin film.

[0053] It should be noted here that the coating is not a key point of protection of the present disclosure, and any materials and / or methods that can be used in the art to coat the endoscope 12 can be selected and applied, and will not be specifically elaborated.

[0054] In such an embodiment, an optical resonator is defined between the two endoscopes 12 and the light transmission holes 112 for a specific frequency laser to pass through.

[0055] Figure 3 It is a three-dimensional view of an ultra-stable cavity device according to an exemplary embodiment of the present disclosure.

[0056] The present disclosure also provides an ultra-stable cavity device, including: an optical reference cavity 1; and a support frame 2 sleeved outside the reference cavity and configured to apply a pressure in the direction of the centroid of the cavity 11 to each support point 114 to limit the position of the reference cavity and make the optical reference cavity have low vibration sensitivity.

[0057] According to an embodiment of the present disclosure, as Figure 3 shown, the support frame 2 includes: two first annular members 21, each first annular member 21 sleeved outside the connecting portion 111 of the cavity 11; and two groups of support members, the first ends of the three support members in each group are installed on the first annular member 21, and the second ends of each support member opposite to the first ends extend out of the first annular member 21 and abut against a support point 114 of the connecting portion 111 to apply a pressure extending from the support point 114 in the direction of the centroid of the cavity 11, so as to limit the position of the reference cavity relative to the support frame 2.

[0058] According to an embodiment of the present disclosure, as Figure 3 shown, three groove-shaped portions 211 are uniformly spaced along the circumferential direction on the inner surface of each first annular member 21, and internal threads are provided on the groove walls of the groove-shaped portions 211; the support member includes a bolt (not shown in the figure), the first end of the bolt is engaged with the internal thread, and the second end of the bolt extends out of the groove-shaped portion 211 and abuts against the support point 114.

[0059] In a schematic embodiment, the ultra-stable cavity device further includes a second annular member 22 sleeved in the middle of the cavity 11 (the circular column structure between the two connecting portions 111), and the axial two ends of the second annular member 22 respectively abut against the ends of the opposite first annular members 21.

[0060] In such an embodiment, it extends out from the inner surface of the first annular member 21 through the cooperation of the bolt and the first annular member 21 to abut against the support point 114 provided on the optical reference cavity 1, so as to apply a pre-tightening force to the cavity 11, so that the cavity 11 is connected to the support frame 2, and then fixed to other mechanisms through the support frame 2 to achieve the portability of the optical reference cavity 1. Based on the ultra-stable cavity device of the above-mentioned exemplary embodiment, through the simulation of finite element analysis software, it can be obtained that the vibration sensitivity reaches the order of E-12 / g under ideal conditions, so as to reach the vibration sensitivity of the optical reference cavity 1 made of the existing ultra-low thermal expansion rate glass (ULE) material. Moreover, the thermal noise level can be greatly reduced at low operating temperatures, and it is expected to optimize the ultra-stable laser stability limit from about 3E-16 to the level of 2E-17 (operating temperature of 4K), which is beneficial to solving the stability limitation problem of the current portable optical clock.

[0061] Those skilled in the art can understand that the features recited in the various embodiments and / or claims of the present invention can be combined or combined in several ways, even if such combinations or combinations are not explicitly recited in the present invention. In particular, without departing from the spirit and teachings of the present invention, the features recited in the various embodiments and / or claims of the present invention can be combined and combined in several ways. All such combinations and / or combinations fall within the scope of the present invention.

[0062] In the specific embodiments described above, the purpose, technical solutions and beneficial effects of the present invention have been further described in detail. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A relocatable optical reference cavity, characterized in that, It includes a cavity (11) made of single-crystalline silicon material. A light passing hole (112) is formed in the cavity (11). The axial direction of the light passing hole (112) is parallel to the 111 crystal orientation of the single-crystalline silicon. And the cavity (11) is configured as a cylindrical structure, and the axis of the cavity (11) coincides with the axis of the light passing hole (112); It further includes a ventilation hole (113), which is configured to extend in a direction orthogonal to the light passing hole (112) and penetrate through the radial two ends of the cavity (11). The axis of the ventilation hole (113) is parallel to the 01-1 crystal orientation of the single-crystalline silicon and passes through the centroid of the cavity (11); The two axial ends of the cavity (11) are respectively configured as connection parts (111) suitable for being assembled with a support frame (2). The connection part (111) is configured as a frustum-shaped structure. The extending direction of the axis of the frustum-shaped structure coincides with the axis of the light passing hole (112). Three support points (114) are evenly spaced along the circumferential direction on the slope surface of the frustum-shaped structure of the connection part (111). The included angle of the connecting lines formed by the three support points (114) to the centroid of the cavity (11) is configured to be 120° when projected along the axial direction of the cavity (11).

2. The reference cavity according to claim 1, wherein The support points (114) provided on the two connection parts (111) are symmetrical along the radial direction of the cavity (11).

3. The reference cavity according to any one of claims 1 or 2, characterized in that, It further includes two cavity mirrors (12). The two cavity mirrors (12) are parallel to each other and are symmetrically arranged at the two axial ends of the light passing hole (112) along a direction orthogonal to the axis of the light passing hole (112).

4. The reference cavity according to claim 3, characterized in that, The two cavity mirrors (12) are installed on the cavity (11) by means of optical cementing.

5. A super-stable cavity device, characterized in that, It includes: The optical reference cavity according to any one of claims 1 to 4; And A support frame (2), sleeved outside the reference cavity and configured to apply a pressure towards the centroid direction of the cavity (11) to each support point (114), so as to limit the position of the reference cavity and make the optical reference cavity have low vibration sensitivity.

6. The ultra-stable cavity device according to claim 5, characterized in that, The support frame (2) includes: Two first annular members (21), each of the first annular members (21) is sleeved outside the connection part (111) of the cavity (11); and Two groups of support members. The first ends of the three support members in each group are installed on the first annular member (21). The second ends of each support member, which are opposite to the first ends, extend out from the first annular member (21) and abut against a support point (114) of the connection part (111), so as to apply a pressure extending from the support point (114) towards the centroid direction of the cavity (11), so as to limit the position of the reference cavity relative to the support frame (2).

7. The ultra-stable cavity device according to claim 6, wherein, Three groove-shaped parts (211) are evenly spaced along the circumferential direction on the inner surface of each first annular member (21). Internal threads are provided on the groove walls of the groove-shaped parts (211); The support member includes a bolt, a first end of the bolt is engaged with the internal thread, and a second end of the bolt extends out of the groove portion (211) and abuts against the support point (114).

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