Optical fiber bubble chamber alkali cell, method of making and filling, and angular rate sensor

Abstract

The application discloses a kind of optical fiber bubble cavity alkali metal cell, comprising: transmission optical fiber, with first end face, second end face and between the first end face and second end face spherical bubble cavity;At least fill in the spherical bubble cavity sealed with alkali metal atom and inert gas.The optical fiber bubble cavity alkali metal cell can guarantee high airtightness, high surface shape precision and good air chamber inner wall state, while it is relatively easy to realize in vacuum cavity to complete air chamber inside alkali metal atom, inert gas, buffer gas and quenching gas release and filling;Using optical fiber bubble cavity can solve high-purity alkali metal atom quantitative filling, inert gas, buffer gas and quenching gas accurate control, structure airtightness and other problems.The application discloses the preparation and filling method of the above-mentioned optical fiber bubble cavity alkali metal cell, and the angular rate sensor comprising the above-mentioned optical fiber bubble cavity alkali metal cell.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of angular rate sensors, in particular to a fiber bubble cavity alkali metal cell, a preparation and filling method and an angular rate sensor. BACKGROUND

[0002] Atomic spin gyroscope is a kind of gyroscope based on atomic spin polarization effect, which can realize high-precision detection compared with traditional relay gyroscopes, laser gyroscopes and optical gyroscopes, and has shown great development potential and application value in military and civilian fields such as inertial navigation, attitude control and scientific research.

[0003] The alkali metal cell is a sensitive element for carrying atomic spins and is a core component of the atomic spin gyroscope. The commonly used alkali metal cells on the market are mostly closed transparent glass chambers manufactured by glass precision fusion process and chip-level chambers bonded by glass-silicon-glass three layers. However, such chambers have many problems such as difficulty in coating inner wall film, discoloration of alkali metal cell due to intensified reaction between alkali metal atoms and glass inner wall, and increased magnetic field gradient caused by integrated heating coil. SUMMARY

[0004] In order to solve the above problems of the prior art, the present application provides a fiber bubble cavity alkali metal cell, which can ensure high airtightness, high surface shape precision and good inner wall state of the chamber, and can easily realize the release and filling of alkali metal atoms, inert gas, buffer gas and quenching gas in the chamber in the vacuum cavity. The use of the fiber bubble cavity can solve the problems of quantitative filling of high-purity alkali metal atoms, accurate control of inert gas, buffer gas and quenching gas, and structural airtightness, which can further improve the performance of the alkali metal cell and promote the development of angular rate sensors in the direction of small size, long life, high performance, miniaturization and integration.

[0005] The present application provides a preparation and filling method of the above-mentioned fiber bubble cavity alkali metal cell, and an angular rate sensor comprising the above-mentioned fiber bubble cavity alkali metal cell.

[0006] The technical problems to be solved by the present application are solved by the following technical solutions:

[0007] A fiber bubble cavity alkali metal cell, comprising:

[0008] A transmission optical fiber having a first end face, a second end face and a spherical bubble cavity between the first end face and the second end face;

[0009] The spherical bubble cavity is at least filled with alkali metal atoms and inert gas.

[0010] Further, the transmission optical fiber comprises a first optical fiber and a second optical fiber, a first half-spherical hole is formed on one side end face of the first optical fiber, and a second half-spherical hole is formed on one side end face of the second optical fiber; the first half-spherical hole and the second half-spherical hole are oppositely fused to form the spherical bubble cavity.

[0011] Further, the first optical fiber comprises a first fiber core and a first cladding layer, the first cladding layer is wrapped around the outer peripheral sidewall of the first fiber core, the second optical fiber comprises a second fiber core and a second cladding layer, the second cladding layer is wrapped around the outer peripheral sidewall of the second fiber core; wherein the first fiber core is aligned with the second fiber core, and the second cladding layer is aligned with the second cladding layer.

[0012] Further, the diameter of the spherical bubble cavity is at least greater than the diameter of the first fiber core and the second fiber core, and the center of the spherical bubble cavity is on the central axis of the first optical fiber and the second optical fiber.

[0013] Further, at least one of buffer gas and quenching gas is filled and sealed in the spherical bubble cavity.

[0014] A preparation and filling method of an optical fiber bubble cavity alkali metal gas cell, comprising the following steps:

[0015] Step 100: respectively manufacturing a first optical fiber with a first half-spherical hole on one side end face and a second optical fiber with a second half-spherical hole on one side end face;

[0016] Step 200: under vacuum environment, aligning the first half-spherical hole of the first optical fiber with the second half-spherical hole of the second optical fiber, and filling at least alkali metal atoms and inert gas in the first half-spherical hole and the second half-spherical hole, and then oppositely fusing the first half-spherical hole and the second half-spherical hole to form the spherical bubble cavity.

[0017] Further, in step 100, the steps of manufacturing the first optical fiber with the first half-spherical hole on one side end face or manufacturing the second optical fiber with the second half-spherical hole on one side end face are as follows:

[0018] Step 110: forming a micro-cavity at the center of a section of optical fiber by using femtosecond laser;

[0019] Step 120: heating the micro-cavity in the section of optical fiber, locally softening the section of optical fiber near the micro-cavity, and expanding and enlarging the micro-cavity to form the spherical bubble cavity;

[0020] Step 130: cutting the spherical bubble cavity to make the section of optical fiber into the first optical fiber with the first half-spherical hole or the second optical fiber with the second half-spherical hole.

[0021] Further, in step 200, the first half-spherical hole of the first optical fiber and the second half-spherical hole of the second optical fiber are aligned with each other in a vacuum environment, and at least alkali metal atoms and inert gas are filled in the first half-spherical hole and the second half-spherical hole, and then the first half-spherical hole and the second half-spherical hole are fused to form the spherical bubble cavity. The steps are as follows:

[0022] Step 210: placing the first optical fiber, the second optical fiber, and the alkali metal element in a sealed chamber, wherein the first half-spherical hole and the second half-spherical hole are opposite to each other;

[0023] Step 220: vacuumizing the sealed chamber to form a vacuum environment in the sealed chamber;

[0024] Step 230: exciting the alkali metal element to vaporize and overflow alkali metal atoms, and at the same time, inert gas is introduced into the sealed chamber;

[0025] Step 240: after the first half-spherical hole and the second half-spherical hole are filled with the alkali metal atoms and the inert gas, the relative position between the first optical fiber and the second optical fiber is adjusted to align the first half-spherical hole and the second half-spherical hole with each other and abut to form the spherical bubble cavity;

[0026] Step 250: fusing and fixing the first half-spherical hole and the second half-spherical hole to seal the alkali metal atoms and the inert gas in the spherical bubble cavity.

[0027] Further, in step 230, at least one of buffer gas and quenching gas is introduced into the vacuum environment at the same time.

[0028] An angular rate sensor includes the above-mentioned optical fiber bubble cavity alkali metal cell magnetic shielding box, non-magnetic heating box, magnetic field generator, pump laser, optical fiber circular polarizer, probe laser, optical fiber linear polarizer, optical fiber coupler, optical fiber filter, and polarization analyzer. The magnetic shielding box is arranged outside the optical fiber bubble cavity alkali metal cell. The non-magnetic heating box and the magnetic field generator are arranged between the optical fiber bubble cavity alkali metal cell and the magnetic shielding box. The optical fiber circular polarizer is connected between the pump laser and the optical fiber coupler. The optical fiber linear polarizer is connected between the probe laser and the optical fiber coupler. The optical fiber coupler is connected with the first end surface of the optical fiber bubble cavity alkali metal cell. The optical fiber filter is connected with the second end surface of the optical fiber bubble cavity alkali metal cell. The polarization analyzer is connected with the optical fiber filter.

[0029] The alkali metal cell with a fiber bubble cavity has the following advantages: the fiber bubble cavity alkali metal cell provided by the application takes a spherical bubble cavity inside a transmission fiber as a carrier, and by filling the spherical bubble cavity with alkali metal atoms and inert gas, high air tightness, high surface shape precision and good inner wall state of the cell can be ensured, and the release and filling of the alkali metal atoms and the inert gas in a vacuum environment can be easily realized; the spherical bubble cavity can solve the problems of quantitative filling of high-purity alkali metal atoms, accurate control of the inert gas and structural air tightness, and can further improve the performance of the alkali metal cell, and thus promote the development of the angular rate sensor in the direction of small size, long service life, high performance, miniaturization and integration. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 A structure schematic diagram of the fiber bubble cavity alkali metal cell provided by the application is shown.

[0031] Figure 2 A decomposition structure schematic diagram of the transmission fiber in the fiber bubble cavity alkali metal cell provided by the application is shown.

[0032] Figure 3 A step block diagram of the preparation and filling method provided by the application is shown.

[0033] Figure 4 A sub-step block diagram of step 100 in the preparation and filling method provided by the application is shown.

[0034] Figure 5 A sub-step block diagram of step 200 in the preparation and filling method provided by the application is shown.

[0035] Figure 6 A structure schematic diagram of the micro-cavity in the preparation and filling method provided by the application is shown.

[0036] Figure 7 A structure schematic diagram of the micro-cavity after expansion in the preparation and filling method provided by the application is shown.

[0037] Figure 8 A structure schematic diagram of the preparation and filling system provided by the application is shown.

[0038] Figure 9 A structure schematic diagram of the angular rate sensor provided by the application is shown. DETAILED DESCRIPTION

[0039] The application will be described in detail below with reference to the accompanying drawings and examples, wherein the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout the drawings. The examples described below by reference to the drawings are exemplary and are intended to explain the application, and cannot be understood as a limitation of the application.

[0040] In the description of the present application, it is to be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0041] In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second", "third" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0042] In the present application, unless otherwise specifically defined and limited, the terms "mounting", "connection", "connection", "fixing", "setting" and the like should be broadly understood, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can also be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0043] Embodiment one

[0044] As shown in Figure 1 A fiber bubble cavity alkali metal cell, comprising:

[0045] The transmission optical fiber 100 has a first end face, a second end face, and a spherical bubble cavity 101 between the first end face and the second end face;

[0046] The spherical bubble cavity 101 is filled with at least sealed alkali metal atoms 200 and inert gas 300.

[0047] The fiber bubble cavity alkali metal cell of the application takes the spherical bubble cavity 101 inside the transmission fiber 100 as a carrier, and is formed by filling the alkali metal atoms 200 and inert gas 300 into the spherical bubble cavity 101, which can ensure high airtightness, high surface shape accuracy and good gas chamber inner wall state, and is relatively easy to realize the release and filling of the alkali metal atoms 200 and inert gas 300 in a vacuum environment; the spherical bubble cavity 101 can solve the problems of quantitative filling of high-purity alkali metal atoms 200, accurate control of the inert gas 300, structural airtightness and the like, and can further improve the performance of the alkali metal cell, thereby promoting the development of the angular rate sensor in the direction of small size, long service life, high performance, miniaturization and integration.

[0048] In use, the pump light and the probe light are coupled into the transmission fiber 100 from the first end face, the pump light is circularly polarized light, and the probe light is linearly polarized light. The pump light excites the alkali metal atoms 200 in the spherical bubble cavity 101 to be electron spin polarized, and the alkali metal atoms 200 cause the nuclear spin polarization of the inert gas 300 through a spin exchange collision mechanism. Under a static magnetic field, the inert gas 300 with nuclear spin polarization rotates around the static magnetic field to do Larmor precession, and the precession frequency is related to the static magnetic field. When the angular rate sensor rotates around the static magnetic field together with the carrier, the precession frequency of the nuclear spin of the inert gas 300 will drift, and the drift amount is the angular rate of the angular rate sensor. The drift of the precession frequency will cause the polarization plane of the probe light to rotate, and by detecting the rotation speed of the polarization plane of the probe light, the drift amount of the precession frequency can be calculated, and then the angular rate of the angular rate sensor can be calculated.

[0049] As shown in Figure 2 The transmission fiber 100 includes a first optical fiber 110 and a second optical fiber 120. A first hemispherical hole 102 is formed on one side end face of the first optical fiber 110, and a second hemispherical hole 103 is formed on one side end face of the second optical fiber 120. The first hemispherical hole 102 and the second hemispherical hole 103 are fused to form the spherical bubble cavity 101.

[0050] The first optical fiber 110 includes a first fiber core 111 and a first cladding 112, and the first cladding 112 surrounds the outer peripheral sidewall of the first fiber core 111. The second optical fiber 120 includes a second fiber core 121 and a second cladding 122, and the second cladding 122 surrounds the outer peripheral sidewall of the second fiber core 121. The first fiber core 111 is aligned with the second fiber core 121, and the second cladding 122 is aligned with the second cladding 122, so that the light beam transmitted in the first fiber core 111 can be incident into the second fiber core 121 for continuous transmission after passing through the spherical bubble cavity 101.

[0051] The diameter of the spherical bubble cavity 101 is at least larger than the diameter of the first and second cores 111 and 121, and preferably, the diameter of the spherical bubble cavity 101 is slightly larger than the outer diameter of the first and second cladding layers 112 and 122, and the center of the spherical bubble cavity 101 is on the central axis of the first and second optical fibers 110 and 120.

[0052] The spherical bubble cavity 101 is also filled with at least one of a buffer gas 400 (inert gas 300 without nuclear spin) and a quenching gas 500 (diatomic molecule).

[0053] The buffer gas 400 is used to collide with the alkali metal atoms 200 to reduce the collision of the alkali metal atoms 200 with the cavity wall of the spherical bubble cavity 101, reduce the depolarization rate of the alkali metal atoms 200, and reduce the photon energy required for the polarization of the alkali metal atoms 200, thereby increasing the polarization rate of the alkali metal atoms 200; the quenching gas 500 is used to absorb the resonance photons spontaneously emitted by the alkali metal atoms 200 when they recover from the excited state to the ground state, so as to avoid the resonance photons causing other alkali metal atoms 200 to retransition from the ground state to the excited state and causing depolarization, thereby reducing the depolarization rate of the alkali metal atoms 200.

[0054] The alkali metal atoms 200 can be but are not limited to cesium atoms (Cs) or rubidium atoms (Rb), and the inert gas 300 can be but is not limited to xenon, neon or helium (He), and the buffer gas 400 can be but is not limited to helium (He), and the quenching gas 500 can be but is not limited to nitrogen. 3 4

[0055] Embodiment Two

[0056] A preparation and filling method of an optical fiber bubble cavity alkali metal cell, for preparing and filling the optical fiber bubble cavity alkali metal cell of embodiment one; as shown in the figure, the preparation and filling method comprises the following steps: Figure 3

[0057] Step 100: respectively manufacturing a first optical fiber 110 with a first hemispherical hole 102 on one side end face, and a second optical fiber 120 with a second hemispherical hole 103 on one side end face.

[0058] ​​​In this step 100, the diameter of the first semi-spherical hole 102 is at least larger than the core diameter of the first optical fiber 110, and preferably, the diameter of the first semi-spherical hole 102 is slightly larger than the cladding outer diameter of the first optical fiber 110, and the center of the first semi-spherical hole 102 is on the central axis of the first optical fiber 110. Similarly, the diameter of the second semi-spherical hole 103 is at least larger than the core diameter of the second optical fiber 120, and preferably, the diameter of the second semi-spherical hole 103 is slightly larger than the cladding outer diameter of the second optical fiber 120, and the center of the second semi-spherical hole 103 is on the central axis of the second optical fiber 120. The size of the first semi-spherical hole 102 is completely consistent with the size of the second semi-spherical hole 103, so that the two can be relatively combined into the spherical bubble cavity 101.

[0059] Specifically, as shown in FIG. 1, in this step 100, the first optical fiber 110 with the first semi-spherical hole 102 on one side end face is made, or the second optical fiber 120 with the second semi-spherical hole 103 on one side end face is made, as follows: Figure 4

[0060] Step 110: As shown in FIG. 2, a femtosecond laser is used to form a micro-cavity 101' at the center of a section of optical fiber 100'. Figure 6

[0061] In this step 110, the femtosecond laser is a non-thermal effect processing technology based on the interaction of nonlinear effects and transparent media such as optical fibers, and can pass through the transparent medium on the transmission path and only act on the transparent medium at the focal point. It acts on the center of the section of optical fiber 100' to produce a local high concentration of plasma group at the center of the section of optical fiber 100', so that the density at the center instantaneously increases, the medium densifies and produces an expanding micro-explosion, and the micro-explosion leaves the micro-cavity 101' at the center. The micro-cavity 101' is located in the core of the section of optical fiber 100'.

[0062] Step 120: As shown in FIG. 3, the micro-cavity 101' in the section of optical fiber 100' is heated to locally soften the section of optical fiber 100' near the micro-cavity 101', and the micro-cavity 101' is expanded and enlarged to form the spherical bubble cavity 101. Figure 7

[0063] In this step 120, the micro-cavity 101' is filled with gas formed by local vaporization of the optical fiber material, and when heated, the gas in the micro-cavity 101' expands due to heating, and at the same time, the local optical fiber near the micro-cavity 101' is also heated and softened, and the expanding gas can expand the size of the micro-cavity 101' to form the spherical bubble cavity 101. ​​​

[0064] Specifically, the segment of optical fiber 100' can be placed in a fiber fusion machine, and the micro-cavity 101' of the segment of optical fiber 100' is discharged and heated by a discharge system for fusing optical fibers in the fiber fusion machine. During heating, the micro-cavity 101' can be heated by multiple discharges, gradually increasing the discharge power and adjusting the discharge position, so that the micro-cavity 101' is gradually expanded to a spherical bubble cavity 101 of the required roundness and size by multiple heating, while a weak stress and coaxial rotation function are applied to the segment of optical fiber 100', so that the micro-cavity 101' is uniformly heated.

[0065] The micro-cavity 101' should at least be expanded to the cladding of the segment of optical fiber 100', that is, the diameter of the spherical bubble cavity 101 should be at least greater than the core diameter of the segment of optical fiber 100', and preferably, the diameter of the spherical bubble cavity 101 can be slightly greater than the outer diameter of the cladding of the segment of optical fiber 100'.

[0066] Step 130: cutting the spherical bubble cavity 101 to form the first optical fiber 110 with the first half-spherical hole 102 or the second optical fiber 120 with the second half-spherical hole 103.

[0067] In this step 130, the spherical bubble cavity 101 is cut by a femtosecond laser to avoid the influence of heat effect on the size, roundness, etc. of the spherical bubble cavity 101 during cutting. If the lengths of the optical fibers on both sides of the spherical bubble cavity 101 are sufficient, the two segments of optical fibers with half-spherical holes formed after cutting can be used as the first optical fiber 110 and the second optical fiber 120, respectively. If the length of the optical fiber on one side of the spherical bubble cavity 101 is insufficient, the optical fiber on the other side with a half-spherical hole formed after cutting is used as the first optical fiber 110, and then steps 110-130 are repeated to make another segment of optical fiber 100' with a half-spherical hole as the second optical fiber 120.

[0068] Step 200: aligning the first half-spherical hole 102 of the first optical fiber 110 with the second half-spherical hole 103 of the second optical fiber 120 in a vacuum environment, filling at least alkali metal atoms 200 and inert gas 300 into the first half-spherical hole 102 and the second half-spherical hole 103, and then fusing the first half-spherical hole 102 and the second half-spherical hole 103 to form the spherical bubble cavity 101.

[0069] In this step 200, a self-built preparation and filling system is used to align, inflate and seal the first optical fiber 110 and the second optical fiber 120. For example, the first optical fiber 110 and the second optical fiber 120 are placed in a vacuum environment, and then the first half-spherical hole 102 of the first optical fiber 110 and the second half-spherical hole 103 of the second optical fiber 120 are aligned. Figure 8As shown, the preparation and filling system includes a sealed chamber 1, a welding device 2, a first displacement platform 3, a second displacement platform 4, a vaporization device 5, an alkali metal element 6, a vacuum device 7, a first gas cylinder 9 filled with inert gas 300, and a host computer 8. The welding device 2, the first displacement platform 3, the second displacement platform 4, the vaporization device 5, and the alkali metal element 6 are all located inside the sealed chamber 1, while the vacuum device 7, the first gas cylinder 9, and the host computer 8 are all located outside the sealed chamber 1. The vacuum device 7 and the first gas cylinder 9 are connected to the sealed chamber 1, and the host computer 8 is connected to control the welding device 2, the first displacement platform 3, the second displacement platform 4, and the vaporization device 5.

[0070] The vacuum pumping device 7 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 300 into the sealed chamber 1; the vaporization device 5 is used to vaporize the alkali metal element 6 to form alkali metal atoms 200; the first displacement platform 3 and the second displacement platform 4 are used to drive the first optical fiber 110 and the second optical fiber 120 to move respectively; the fusion splicing device 2 is used to fusion splice the first hemispherical hole 102 and the second hemispherical hole 103.

[0071] Preferably, the preparation and filling system further includes at least one of a second gas cylinder 10 filled with buffer gas 400 and a third gas cylinder 11 filled with quenching gas 500, wherein both the second gas cylinder 10 and the third gas cylinder 11 are located outside the sealed chamber 1 and communicate with the sealed chamber 1. The second gas cylinder 10 is used to introduce the buffer gas 400 into the sealed chamber 1, and the third gas cylinder 11 is used to introduce the quenching gas 500 into the sealed chamber 1.

[0072] In this embodiment, the welding device 2 is a carbon dioxide laser device, the first displacement platform 3 and the second displacement platform 4 are both triaxial displacement platforms, and the vaporization device 5 is an ultraviolet laser device.

[0073] Specifically, such as Figure 5 As shown, in step 200, the first hemispherical aperture 102 of the first optical fiber 110 and the second hemispherical aperture 103 of the second optical fiber 120 are aligned with each other, and at least alkali metal atoms 200 and inert gas 300 are filled into the first hemispherical aperture 102 and the second hemispherical aperture 103. Then, the first hemispherical aperture 102 and the second hemispherical aperture 103 are fused together to form the spherical bubble cavity 101 as follows:

[0074] Step 210: Place the first optical fiber 110, the second optical fiber 120, and the alkali metal element 6 in the sealed chamber 1, wherein the first hemispherical hole 102 and the second hemispherical hole 103 are opposite each other.

[0075] In this step 210, the first optical fiber 110 and the second optical fiber 120 are respectively placed on the first displacement platform 3 and the second displacement platform 4 in the sealed chamber 1, so that the first half-spherical hole 102 and the second half-spherical hole 103 are opposite. Preferably, the alkali metal element 6 is placed below the gap between the first half-spherical hole 102 and the second half-spherical hole 103, so that the alkali metal atoms 200 overflowing from the alkali metal element 6 can quickly pass through the gap between the first half-spherical hole 102 and the second half-spherical hole 103 into the first half-spherical hole 102 and the second half-spherical hole 103.

[0076] Step 220: vacuumize the sealed chamber 1 to form a vacuum environment in the sealed chamber 1.

[0077] In this step 220, the vacuumizing device 7 is started to pump the sealed chamber 1, and the pumping is stopped when the sealed chamber 1 reaches the required vacuum degree.

[0078] Step 230: excite the alkali metal element 6 to make the alkali metal element 6 overflow the alkali metal atoms 200, and simultaneously introduce inert gas 300 into the sealed chamber 1.

[0079] In this step 230, a high-power ultraviolet laser is used to emit ultraviolet laser to the alkali metal element 6 to increase the temperature of the alkali metal element 6, so that the alkali metal element 6 overflows the alkali metal atoms 200. The alkali metal atoms 200 are mixed in the sealed chamber 1 or in the first half-spherical hole 102 and the second half-spherical hole 103. By controlling the amount of inert gas 300 introduced and the irradiation time of the ultraviolet laser, the mixing ratio between the alkali metal element 6 and the inert gas 300 can be adjusted.

[0080] In this step 230, at least one of the buffer gas 400 and the quenching gas 500 can also be introduced into the vacuum environment at the same time. By controlling the amount of buffer gas 400 and quenching gas 500 introduced, the mixing ratio between the alkali metal element 6, inert gas 300, buffer gas 400 and quenching gas 500 can be adjusted.

[0081] Step 240: after the first half-spherical hole 102 and the second half-spherical hole 103 are filled with the alkali metal atoms 200 and the inert gas 300, the relative position between the first optical fiber 110 and the second optical fiber 120 is adjusted, so that the first half-spherical hole 102 and the second half-spherical hole 103 are aligned with each other and abutted to form the spherical bubble cavity 101.

[0082] In step 240, the first displacement device and the second displacement device are used to drive the first optical fiber 110 and the second optical fiber 120 to move, so as to adjust the relative position between the first hemispherical hole 102 and the second hemispherical hole 103, so that the first hemispherical hole 102 and the second hemispherical hole 103 are aligned and abutted together, and the first hemispherical hole 102 and the second hemispherical hole 103 form a fused spherical bubble cavity 101 after abutting.

[0083] Step 250: The first hemispherical hole 102 and the second hemispherical hole 103 are welded and fixed to each other to seal the alkali metal atoms 200 and the inert gas 300 in the spherical bubble cavity 101.

[0084] In step 250, the carbon dioxide laser device emits a high-power carbon dioxide laser at the interface between the first hemispherical hole 102 and the second hemispherical hole 103, causing the interface between the first hemispherical hole 102 and the second hemispherical hole 103 to melt and connect together.

[0085] Example 3

[0086] like Figure 9 As shown, an angular rate sensor includes the fiber optic bubble chamber alkali metal gas chamber 12 described in Embodiment 1, as well as a magnetic shielding box 13, a non-magnetic heating box 14, a magnetic field generator 15, a pump laser 16, a fiber circular polarizer 17, a probe laser 18, a fiber line polarizer 19, a fiber coupler 20, a fiber filter 21, and a polarization analyzer 22. The magnetic shielding box 13 is disposed outside the fiber optic bubble chamber alkali metal gas chamber 12, and the non-magnetic heating box 14 and the magnetic field generator 15 are disposed inside the fiber optic bubble chamber alkali metal gas chamber 12. Between the metal gas chamber 12 and the magnetic shielding box 13, the fiber circular polarizer 17 is connected between the pump laser 16 and the fiber coupler 20, the fiber line polarizer 19 is connected between the probe laser 18 and the fiber coupler 20, the fiber coupler 20 is connected to the first end face of the fiber bubble cavity alkali metal gas chamber 12, the fiber filter 21 is connected to the second end face of the fiber bubble cavity alkali metal gas chamber 12, and the polarization analyzer 22 is connected to the fiber filter 21.

[0087] The fiber circular polarizer 17 is used to convert the pumping light emitted by the pumping laser 16 into circularly polarized light; the fiber linear polarizer 19 is used to convert the probe light emitted by the probe laser 18 into linearly polarized light; the fiber coupler 20 is used to mix the pumping light and the probe light in a predetermined ratio and then couple them into the transmission fiber 100 of the fiber bubble chamber alkali gas cell 12; the fiber filter 21 is used to filter out the circularly polarized light emitted from the transmission fiber 100 of the fiber bubble chamber alkali gas cell 12; and the polarization analyzer 22 is used to receive the linearly polarized light emitted from the transmission fiber 100 of the fiber bubble chamber alkali gas cell 12 and then analyze the rotation speed of the polarization plane of the linearly polarized light.

[0088] The magnetic shielding box 13 is used to shield the external magnetic field to avoid the disturbance of the external magnetic field to the polarization of the alkali metal atoms 200 and the noble gas 300; the non-magnetic heating box 14 is used to heat the fiber bubble chamber alkali gas cell 12 to increase the number density of the alkali metal atoms 200; and the magnetic field generator 15 is used to provide the fiber bubble chamber alkali gas cell 12 with static magnetic fields in the X-axis, Y-axis and Z-axis directions.

[0089] The optical frequency of the pumping light is the same as the inherent frequency of the alkali metal atoms 200, so that it can resonate with the alkali metal atoms 200 and then cause the electron spin polarization of the alkali metal atoms 200. The optical frequency of the probe light is far away from the inherent frequency of the alkali metal atoms 200 as much as possible to avoid affecting the electron spin polarization of the alkali metal atoms 200.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present application rather than limit them, and although the embodiments of the present application have been 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 present application can still be modified or replaced by equivalents, and these modifications or equivalent replacements should not make the modified technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing and filling an alkali metal gas chamber in an optical fiber bubble cavity, characterized in that, Includes the following steps: Step 100: Fabricate a first optical fiber with a first hemispherical hole on one end face and a second optical fiber with a second hemispherical hole on one end face; Step 200: In a vacuum environment, align the first hemispherical hole of the first optical fiber with the second hemispherical hole of the second optical fiber, and fill the first hemispherical hole and the second hemispherical hole with at least alkali metal atoms and inert gas, and then weld the first hemispherical hole and the second hemispherical hole together to form a spherical bubble cavity. In step 100, the steps for fabricating a first optical fiber with a first hemispherical hole on one end face, or fabricating a second optical fiber with a second hemispherical hole on one end face, are as follows: Step 110: A micro-cavity is formed at the center of a section of optical fiber using a femtosecond laser; Step 120: Heat the micro-cavity in the fiber segment to soften the fiber segment near the micro-cavity and cause the micro-cavity to expand and form a spherical bubble cavity. Step 130: Cut the spherical bubble cavity to form a first optical fiber with the first hemispherical hole or a second optical fiber with the second hemispherical hole; In step 200, under a vacuum environment, the first hemispherical aperture of the first optical fiber and the second hemispherical aperture of the second optical fiber are aligned with each other, and at least alkali metal atoms and inert gas are filled into the first and second hemispherical apertures. Then, the first and second hemispherical apertures are fused together to form the spherical bubble cavity. Step 210: Place the first optical fiber, the second optical fiber, and the alkali metal element in a sealed chamber, wherein the first hemispherical hole and the second hemispherical hole are opposite to each other; Step 220: Evacuate the sealed chamber to create a vacuum environment; Step 230: Excite the alkali metal element to vaporize and release alkali metal atoms, while simultaneously introducing an inert gas into the sealed chamber; Step 240: After the first hemispherical hole and the second hemispherical hole are filled with the alkali metal atoms and inert gas, adjust the relative position between the first optical fiber and the second optical fiber so that the first hemispherical hole and the second hemispherical hole are aligned with each other and abut against each other to form the spherical bubble cavity. Step 250: The first hemispherical hole and the second hemispherical hole are welded and fixed together to seal the alkali metal atoms and inert gas in the spherical bubble cavity.

2. The preparation and filling method according to claim 1, characterized in that, In step 230, at least one of a buffer gas and a quenching gas is simultaneously introduced into the vacuum environment.

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