Alkali metal air chamber based on optical fiber bubble cavity

Abstract

The utility model discloses an alkali metal air chamber based on an optical fiber bubble cavity, which comprises a first optical fiber, a second optical fiber, a third optical fiber and the optical fiber bubble cavity, and the end faces of one sides of the first optical fiber, the second optical fiber and the third optical fiber are respectively connected to the surface of the optical fiber bubble cavity; wherein the central axis of the second optical fiber coincides with the central axis of the third optical fiber, and the central axis of the first optical fiber is perpendicular to the central axes of the second optical fiber and the third optical fiber; the optical fiber bubble cavity is at least filled with alkali metal atoms and inert gas in a sealed mode. The alkali metal air chamber can ensure high air tightness, high surface shape precision and good inner wall state of the air chamber.

Description

Technical Field

[0001] The utility model relates to an angular rate sensor technology, in particular to an alkali metal gas chamber. Background Art

[0002] As the core sensitive component of the inertial navigation system, the gyroscope directly determines the accuracy of the navigation and guidance system and the ground reconnaissance platform, and is a vital part of the inertial navigation system and the stable platform. At present, the market mainly uses micro-electromechanical gyroscopes, laser gyroscopes and atomic gyroscopes to achieve high-precision autonomous navigation, but they have disadvantages such as high cost, large size, poor anti-electromagnetic interference ability, and are difficult to mass produce. It is also difficult to achieve continuous and reliable navigation in complex environments such as underground and underwater.

[0003] The alkali metal gas chamber is a sensitive element that carries the atomic spin in the atomic gyroscope and is the core component of the atomic gyroscope. Currently, the alkali metal gas chambers commonly used in the market are mostly closed transparent glass chambers manufactured by glass precision welding technology and chip-level gas chambers with glass-silicon-glass three-layer bonding. However, this type of gas chamber has many problems, such as the difficulty of coating the inner wall film layer, the alkali metal gas chamber is prone to discoloration due to the intensified reaction between the alkali metal atoms and the inner wall of the glass, and the integrated heating coil causes an increase in the magnetic field gradient. Utility Model Content

[0004] In order to solve the above-mentioned deficiencies in the prior art, the utility model provides an alkali metal gas chamber, which can ensure high air tightness, high surface accuracy and good gas chamber inner wall state.

[0005] The technical problem to be solved by the utility model is achieved through the following technical solutions:

[0006] An alkali metal gas chamber based on an optical fiber bubble cavity comprises a first optical fiber, a second optical fiber, a third optical fiber and an optical fiber bubble cavity, wherein one side end faces of the first optical fiber, the second optical fiber and the third optical fiber are respectively connected to the surface of the optical fiber bubble cavity; wherein the central axis of the second optical fiber coincides with the central axis of the third optical fiber, and the central axis of the first optical fiber is perpendicular to the central axes of the second optical fiber and the third optical fiber; and the optical fiber bubble cavity is sealed and filled with at least alkali metal atoms and an inert gas.

[0007] Furthermore, a first open air hole is formed on one end face of the first optical fiber, a second open air hole is formed on one end face of the second optical fiber, and a third open air hole is formed on one end face of the third optical fiber. The first open air hole, the second open air hole and the third open air hole are aligned and fused with each other to form the optical fiber bubble cavity.

[0008] Furthermore, the optical fiber bubble cavity is also filled and sealed with at least one of a buffer gas and a quenching gas.

[0009] Furthermore, the first optical fiber is a polarization-maintaining optical fiber, and the second optical fiber and the third optical fiber are single-mode optical fibers.

[0010] The utility model has the following beneficial effects: the alkali metal gas chamber of the utility model uses the optical fiber bubble cavity inside the optical fiber as a carrier, and is formed by filling the optical fiber bubble cavity with the alkali metal atoms and the inert gas, which can ensure high air tightness, high surface accuracy and a good state of the inner wall of the gas chamber, and at the same time it is easier to achieve the release and filling of the alkali metal atoms and the inert gas in a vacuum environment; the optical fiber bubble cavity can be used to solve the problems of quantitative filling of high-purity alkali metal atoms, precise control of the inert gas, structural air tightness, etc., which can further improve the performance of the gas chamber, and further promote the development of angular rate sensors towards small size, long life, high performance, miniaturization and integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a schematic structural diagram of the alkali metal gas chamber provided by the utility model.

[0012] Figure 2 This is a schematic diagram of the exploded structure of the optical fiber bubble cavity in the alkali metal gas chamber provided by the utility model.

[0013] Figure 3 This is a schematic diagram of the structure of the micro-cavity during the preparation of the alkali metal gas chamber provided by the utility model.

[0014] Figure 4 This is a schematic structural diagram of the alkali metal gas chamber provided by the utility model after the micro-gas cavity is expanded during preparation.

[0015] Figure 5 This is a structural schematic diagram of the gas filling system provided by the utility model. DETAILED DESCRIPTION

[0016] The present invention is described in detail below in conjunction with the accompanying drawings and embodiments, examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0017] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0018] In addition, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first", "second", and "third" may explicitly or implicitly include one or more of the features. In the description of the present utility model, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0019] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix", "set" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0020] Embodiment 1

[0021] like Figure 1 As shown, an alkali metal gas chamber based on an optical fiber bubble cavity comprises a first optical fiber 110, a second optical fiber 120, a third optical fiber 130 and an optical fiber bubble cavity 140, wherein one side end faces of the first optical fiber 110, the second optical fiber 120 and the third optical fiber 130 are respectively connected to the surface of the optical fiber bubble cavity 140; wherein the central axis of the second optical fiber 120 coincides with the central axis of the third optical fiber 130, and the central axis of the first optical fiber 110 is perpendicular to the central axes of the second optical fiber 120 and the third optical fiber 130; and the optical fiber bubble cavity 140 is sealed and filled with at least alkali metal atoms 150 and an inert gas 160.

[0022] The alkali metal gas chamber of the utility model uses the optical fiber bubble cavity 140 inside the optical fiber as a carrier, and is formed by filling the optical fiber bubble cavity 140 with the alkali metal atoms 150 and the inert gas 160, which can ensure high air tightness, high surface accuracy and a good state of the inner wall of the gas chamber, and at the same time it is easier to achieve the release and filling of the alkali metal atoms 150 and the inert gas 160 in a vacuum environment; utilizing the optical fiber bubble cavity 140 can solve the problems of quantitative filling of high-purity alkali metal atoms 150, precise control of the inert gas 160, structural air tightness, etc., which can further improve the performance of the gas chamber, and further promote the development of angular rate sensors towards small size, long life, high performance, miniaturization, and integration.

[0023] When in use, the first optical fiber 110 is used for the input of pump light, the second optical fiber 120 is used for the input of detection light, and the third optical fiber 130 is used for the output of detection light. The pump light is circularly polarized light, and the detection light is linearly polarized light. The pump light excites the alkali metal atoms 150 in the optical fiber bubble cavity 140 to generate electronic spin polarization. The alkali metal atoms 150 cause the nuclear spin polarization of the inert gas 160 through the spin exchange collision mechanism. Under the static magnetic field, the inert gas 160 with nuclear spin polarization will perform Larmor precession around the static magnetic field, and the precession frequency is related to the static magnetic field. When the angular velocity sensor rotates around the static magnetic field together with the carrier, the precession frequency of the nuclear spin of the inert gas 160 will drift, and the drift amount is the angular velocity of the angular velocity sensor. The drift of the precession frequency will cause the polarization plane of the detection light to rotate, thereby causing the refractive index of the detection light in the optical fiber bubble cavity 140 to change, and finally causing the light intensity of the detection light to change. The angular velocity of the angular velocity sensor can be inferred by analyzing the light intensity change of the detection light, or directly analyzing the polarization information change of the detection light.

[0024] like Figure 2 As shown, a first open air hole 141 is formed on one end face of the first optical fiber 110, a second open air hole 142 is formed on one end face of the second optical fiber 120, and a third open air hole 143 is formed on one end face of the third optical fiber 130. The first open air hole 141, the second open air hole 142 and the third open air hole 143 are aligned and fused with each other to form the optical fiber bubble cavity 140.

[0025] During preparation, take a section of optical fiber A and Figure 3 As shown in the figure, a femtosecond laser is used to form a micro cavity 144 at the center of the segment of optical fiber A, and the micro cavity 144 is located in the core of the segment of optical fiber A; then, the micro cavity 144 in the segment of optical fiber A is discharged and heated in the optical fiber fusion splicer, so that the segment of optical fiber A is partially softened near the micro cavity 144, and as shown in the figure, Figure 4 As shown, the micro-cavity 144 is expanded to form the optical fiber bubble cavity 140. During heating, the micro-cavity 144 can be heated by multiple discharges and gradually increasing the discharge power and adjusting the discharge position, so that the micro-cavity 144 is gradually expanded to the desired roundness and size through multiple thermal expansions. At the same time, a weak stress and a coaxial rotation function are applied to the section of optical fiber A to make the micro-cavity 144 evenly heated. The micro-cavity 144 should be expanded to at least the cladding of the section of optical fiber A. Then, a femtosecond laser is used to heat the optical fiber bubble cavity of the section of optical fiber A. 140 is cut into open pores to serve as the first optical fiber 110 having the first open pore 141; two sections of optical fiber A are taken to repeat the above steps to respectively form the first optical fiber 110 having the second open pore 142 and the third optical fiber 130 having the third open pore 143; finally, the first open pore 141, the second open pore 142 and the third open pore 143 are filled with the alkali metal atoms 150 and the inert gas 160, and then the first open pore 141, the second open pore 142 and the third open pore 143 are fused and fixed.

[0026] The curvatures of the first open pore 141, the second open pore 142 and the third open pore 143 may be the same or different, mainly when the first optical fiber 110, the second optical fiber 120 and the third optical fiber 130 are combined in a manner that the second optical fiber 120 is parallel to the third optical fiber 130 and the first optical fiber 110 is perpendicular to the second optical fiber 120 and the third optical fiber 130, the first open pore 141, the second open pore 142 and the third open pore 143 can form a complete optical fiber bubble cavity 140. Preferably, the optical fiber bubble cavity 140 is preferably a spherical bubble cavity.

[0027] When filling the gas, a self-built gas filling system is used to perform steps such as alignment, filling and welding of the first optical fiber 110, the second optical fiber 120 and the third optical fiber 130. Figure 5 As shown, the gas filling system includes a sealed chamber 1, a carbon dioxide laser 2, a first displacement platform 3, a second displacement platform 4, a third displacement platform 5, an ultraviolet laser 6, an alkali metal element 7, a vacuum pumping device 8, a first gas cylinder 9 filled with an inert gas 160, and a host computer 12. The carbon dioxide laser 2, the first displacement platform 3, the second displacement platform 4, the third displacement platform 5, the ultraviolet laser 6, and the alkali metal element 7 are all arranged in the sealed chamber 1, and the vacuum pumping device 8, the first gas cylinder 9, and the host computer 12 are all arranged outside the sealed chamber 1; the vacuum pumping device 8 and the first gas cylinder 9 are connected to the sealed chamber 1, and the host computer 12 is connected to control the carbon dioxide laser 2, the first displacement platform 3, the second displacement platform 4, the third displacement platform 5, and the ultraviolet laser 6.

[0028] The vacuum pumping device 8 is used to evacuate the sealed chamber 1 to provide a vacuum environment; the first gas cylinder 9 is used to introduce the inert gas 160 into the sealed chamber 1; the ultraviolet laser 6 is used to vaporize the alkali metal element 7 to form alkali metal atoms 150; the first displacement platform 3, the second displacement platform 4 and the third displacement platform 5 are used to drive the first optical fiber 110, the second optical fiber 120 and the third optical fiber 130 to move respectively; the carbon dioxide laser 2 device is used to fuse the first open pore 141, the second open pore 142 and the third open pore 143.

[0029] Preferably, the gas filling system further comprises at least one of a second gas cylinder 10 filled with a buffer gas 170 and a third gas cylinder 11 filled with a quenching gas 180, wherein the second gas cylinder 10 and the third gas cylinder 11 are both located outside the sealed chamber 1 and connected to the sealed chamber 1. The second gas cylinder 10 is used to pass the buffer gas 170 into the sealed chamber 1, and the third gas cylinder 11 is used to pass the quenching gas 180 into the sealed chamber 1.

[0030] When filling the gas, firstly, the first optical fiber 110, the second optical fiber 120, the third optical fiber 130 and the alkali metal element 7 are placed in the sealed chamber 1, wherein the first open pore 141, the second open pore 142 and the third open pore 143 are arranged relative to each other; then, the ultraviolet laser 6 is used to emit a high-power ultraviolet laser to the alkali metal element 7 to excite the alkali metal to cause the alkali metal to vaporize and overflow, and at the same time, the inert gas 160, the buffer gas 170 and the quenching gas 180 are respectively introduced into the sealed chamber 1 through the first gas cylinder 9, the second gas cylinder 10 and the third gas cylinder 11, so that the sealed chamber 1 is filled with a mixed gas of the alkali metal atoms 150, the inert gas 160, the buffer gas 170 and the quenching gas 180; then, the first displacement platform 3 and the second displacement platform 4 are used to and the third displacement platform 5 to adjust the relative positions among the first optical fiber 110, the second optical fiber 120 and the third optical fiber 130, so that the first open pore 141, the second open pore 142 and the third open pore 143 are aligned with each other and abutted to form an unfused optical fiber bubble cavity 140; finally, the carbon dioxide laser 2 is used to emit a high-power carbon dioxide laser to the abutting surfaces among the first open pore 141, the second open pore 142 and the third open pore 143, so that the abutting surfaces among the first open pore 141, the second open pore 142 and the third open pore 143 are melted and connected together, so as to seal the mixed gas of alkali metal atoms 150, inert gas 160, buffer gas 170 and quenching gas 180 between the first open pore 141, the second open pore 142 and the third open pore 143.

[0031] In this embodiment, the first displacement platform 3, the second displacement platform 4 and the third displacement platform 5 are all three-axis displacement platforms.

[0032] The first optical fiber 110 includes a first core 111 and a first cladding 112, wherein the first cladding 112 surrounds the outer peripheral side wall of the first core 111; the second optical fiber 120 includes a second core 121 and a second cladding 122, wherein the second cladding 122 surrounds the outer peripheral side wall of the second core 121; the third optical fiber 130 includes a third optical fiber core 131 and a third cladding 132, wherein the third cladding 132 surrounds the outer peripheral side wall of the third optical fiber core 131; wherein the second core 121 is aligned with the third optical fiber core 131, and the second cladding 122 is aligned with the third cladding 132, so that the detection light transmitted in the second core 121 can be incident into the third optical fiber core 131 and continue to be transmitted after passing through the optical fiber bubble cavity 140; the third optical fiber core 131 is aligned with the center of the optical fiber bubble cavity 140, so as to improve the polarization uniformity of the detection light to the alkali metal atoms 150 and the inert gas 160.

[0033] The diameter of the optical fiber bubble cavity 140 must be at least larger than the diameters of the first fiber core 111, the second fiber core 121 and the third optical fiber core 131. Preferably, the diameter of the optical fiber bubble cavity 140 may be slightly larger than the outer diameters of the first cladding 112, the second cladding 122 and the third cladding 132, and the center of the optical fiber bubble cavity 140 is at the intersection of the central axes of the second optical fiber 120, the second optical fiber 120 and the third optical fiber 130.

[0034] The first optical fiber 110, the second optical fiber 120 and the third optical fiber 130 can be single-mode optical fibers, the detection light is linearly polarized light, and the pump light is circularly polarized light. In order to maintain the polarization state of the detection light and the pump light during transmission, the first optical fiber 110, the second optical fiber 120 and the third optical fiber 130 can also be polarization-maintaining optical fibers.

[0035] In this embodiment, the first optical fiber 110 is a polarization-maintaining optical fiber, and the second optical fiber 120 and the third optical fiber 130 are single-mode optical fibers.

[0036] The optical fiber bubble cavity 140 is also filled and sealed with at least one of a buffer gas 170 (an inert gas without nuclear spin) and a quenching gas 180 (a diatomic molecule).

[0037] The buffer gas 170 is used to collide with the alkali metal atoms 150 to reduce the collision between the alkali metal atoms 150 and the wall of the optical fiber bubble cavity 140, reduce the depolarization rate of the alkali metal atoms 150, and reduce the photon energy required for the polarization of the alkali metal atoms 150, thereby increasing the polarization rate of the alkali metal atoms 150; the quenching gas 180 is used to absorb the resonant photons spontaneously radiated by the alkali metal atoms 150 when they recover from the excited state to the ground state, thereby preventing the resonant photons from causing other alkali metal atoms 150 to re-transition from the ground state to the excited state and cause depolarization, thereby reducing the depolarization rate of the alkali metal atoms 150.

[0038] The alkali metal atom 150 may be, but is not limited to, cesium atom (Cs) or rubidium atom (Rb), and the inert gas 160 may be, but is not limited to, xenon, neon or helium ( 3 He), etc., the buffer gas 170 may be, but is not limited to, helium ( 4 He), etc., the quenching gas 180 may be but is not limited to nitrogen, etc.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the utility model rather than to limit them. Although the embodiments of the utility model are described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the embodiments of the utility model can still be modified or replaced by equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the scope of the technical solutions of the embodiments of the utility model.

Claims

1. An alkali metal gas chamber based on an optical fiber bubble cavity, characterized in that: It includes a first optical fiber, a second optical fiber, a third optical fiber and an optical fiber bubble cavity, wherein one side end faces of the first optical fiber, the second optical fiber and the third optical fiber are respectively connected to the surface of the optical fiber bubble cavity; wherein the central axis of the second optical fiber coincides with the central axis of the third optical fiber, and the central axis of the first optical fiber is perpendicular to the central axes of the second optical fiber and the third optical fiber; and the optical fiber bubble cavity is sealed and filled with at least alkali metal atoms and an inert gas.

2. The alkali metal gas chamber according to claim 1, characterized in that: A first open air hole is formed on one end face of the first optical fiber, a second open air hole is formed on one end face of the second optical fiber, and a third open air hole is formed on one end face of the third optical fiber. The first open air hole, the second open air hole and the third open air hole are aligned and fused with each other to form the optical fiber bubble cavity.

3. The alkali metal gas chamber according to claim 1, characterized in that: The optical fiber bubble cavity is also filled and sealed with at least one of a buffer gas and a quenching gas.

4. The alkali metal gas chamber according to claim 1, characterized in that: The first optical fiber includes a first core and a first cladding, wherein the first cladding surrounds the outer peripheral side wall of the first core, and the first core is aligned with the center of the optical fiber bubble cavity.

5. The alkali metal gas chamber according to claim 4, characterized in that: The second optical fiber includes a second core and a second cladding, wherein the second cladding surrounds the outer peripheral side wall of the second core; the third optical fiber includes a third optical fiber core and a third cladding, wherein the third cladding surrounds the outer peripheral side wall of the third optical fiber core; wherein the second core is aligned with the third optical fiber core, and the second cladding is aligned with the third cladding.

6. The alkali metal gas chamber according to claim 5, characterized in that: The diameter of the optical fiber bubble cavity is at least larger than the diameters of the first fiber core, the second fiber core and the third fiber core.

7. The alkali metal gas chamber according to claim 5, characterized in that: The diameter of the optical fiber bubble cavity is greater than the outer diameters of the first cladding, the second cladding and the third cladding.

8. The alkali metal gas chamber according to claim 1, characterized in that: The center of the optical fiber bubble cavity is at the intersection of the central axes of the second optical fiber, the third optical fiber and the third optical fiber.

9. The alkali metal gas chamber according to claim 1, characterized in that: The first optical fiber, the second optical fiber and the third optical fiber are single-mode optical fibers or polarization-maintaining optical fibers.

10. The alkali metal gas chamber according to claim 1, characterized in that: The first optical fiber is a polarization-maintaining optical fiber, and the second optical fiber and the third optical fiber are single-mode optical fibers.

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