Alkali metal cell based on a tee glass tube, method of preparation and filling, and angular rate sensor

Abstract

The application discloses an alkali metal cell based on a three-way glass tube, which comprises a three-way glass tube, a first optical fiber collimator and a second optical fiber collimator, the three-way glass tube is provided with a first channel, a second channel and a third channel which are connected, the first channel and the second channel are in a straight-through structure, and the third channel is in a non-straight-through structure with the first channel and the second channel; the first optical fiber collimator and the second optical fiber collimator are respectively sealed in the first channel and the second channel of the three-way glass tube, and the first optical fiber collimator and the second optical fiber collimator are aligned with each other; the third channel of the three-way glass tube is sealed, and the three-way glass tube is filled with at least alkali metal atoms and inert gas. The alkali metal cell has the advantages of small volume, simple preparation and the like. The application discloses a preparation and filling method of the alkali metal cell and an angular rate sensor based on the alkali metal cell.

Description

TECHNICAL FIELD

[0001] The present application relates to angular rate sensing technology, in particular to an alkali metal cell, a preparation and filling method and an angular rate sensor. BACKGROUND

[0002] Navigation is one of the key technologies for providing position, velocity and attitude information in the fields of sea, land, air and space. Among them, inertial navigation does not need to receive any external information, can realize the full autonomous navigation of the carrier or device, has the advantages of all-weather, strong anti-interference ability, good concealment, complete navigation information and high data update rate, and is the most important means of motion information acquisition. As the core sensitive device of the inertial navigation system, the gyroscope determines the overall performance of the inertial navigation system.

[0003] With the development of quantum control technology, the development of atomic gyroscope based on atomic spin for inertial measurement is promoted. The traditional atomic spin gyroscope has problems such as large volume of alkali metal cell, complex preparation, and the pump light path and the detection light path are spatially separated, and the atomic polarization and gyroscope effect detection in the cell are realized by using spatial light path, which also directly leads to the problems of system instability and low efficiency. SUMMARY

[0004] In order to solve the above problems of the prior art, the present application provides an alkali metal cell based on a three-way glass tube, which has the advantages of small volume and simple preparation.

[0005] The present application provides a preparation and filling method of the above alkali metal cell and an angular rate sensor based on the above alkali metal cell.

[0006] The technical problem to be solved by the present application is solved by the following technical scheme:

[0007] An alkali metal cell based on a three-way glass tube, comprising a three-way glass tube, a first optical fiber collimator and a second optical fiber collimator, the three-way glass tube has a first channel, a second channel and a third channel connected in communication, the first channel and the second channel are in a straight-through structure, and the third channel is in a non-straight-through structure with the first channel and the second channel; the first optical fiber collimator and the second optical fiber collimator are respectively sealed in the first channel and the second channel of the three-way glass tube, and the first optical fiber collimator and the second optical fiber collimator are aligned with each other; the third channel of the three-way glass tube is sealed, and the three-way glass tube is at least filled with alkali metal atoms and inert gas.

[0008] Further, the three-way glass tube is further filled with at least one of buffer gas and quenching gas.

[0009] A preparation and filling method of an alkali metal cell, comprising the following steps:

[0010] Step 100: providing a three-way glass tube having a first channel, a second channel and a third channel in communication, the first channel and the second channel being in straight-through structure, the third channel being in non-straight-through structure with the first channel and the second channel;

[0011] Step 200: providing a first optical fiber collimator and a second optical fiber collimator, and sealing the first optical fiber collimator and the second optical fiber collimator in the first channel and the second channel of the three-way glass tube, respectively;

[0012] Step 300: filling at least alkali metal atoms and inert gas into the three-way glass tube through the third channel;

[0013] Step 400: sealing the third channel of the three-way glass tube.

[0014] Further, in step 300, at least one of buffer gas and quenching gas is also filled into the three-way glass tube through the third channel.

[0015] Further, a preparation and filling system is used to fill at least alkali metal atoms and inert gas into the three-way glass tube through the third channel; the preparation and filling system comprises a vacuum pump, an alkali metal container, an alkali metal heater, a first gas bottle and a connecting pipeline, the vacuum pump is connected to the connecting pipeline through a gas extraction pipeline, the alkali metal container is connected to the connecting pipeline through an alkali metal pipeline, the first gas bottle is connected to the connecting pipeline through a first gas outlet pipeline, the connecting pipeline is connected to the third channel of the three-way glass tube; the first gas bottle is filled with the inert gas, the alkali metal container contains an alkali metal releasing agent, and the alkali metal heater is used to heat the alkali metal releasing agent in the alkali metal container.

[0016] Further, in step 300, the preparation and filling system is used to fill at least alkali metal atoms and inert gas into the three-way glass tube through the third channel as follows:

[0017] Step 310: using the vacuum pump to perform vacuum extraction on the three-way glass tube through the gas extraction pipeline and the connecting pipeline, so that the vacuum degree of the three-way glass tube reaches a preset value;

[0018] Step 320: using the first gas bottle to fill the inert gas into the three-way glass tube through the first gas outlet pipeline and the connecting pipeline;

[0019] Step 330: heating the alkali metal releasing agent in the alkali metal container by the alkali metal heater, so that the alkali metal releasing agent releases alkali metal atoms, and the alkali metal atoms are filled into the three-way glass tube through the alkali metal pipeline and the connecting pipeline.

[0020] Further, the preparation and filling system further comprises at least one of a second gas cylinder and a third gas cylinder, the second gas cylinder is connected with the connecting pipeline through a second gas outlet pipeline, and the third gas cylinder is connected with the connecting pipeline through a third gas outlet pipeline; the second gas cylinder is filled with buffer gas, and the third gas cylinder is filled with quenching gas.

[0021] Further, in step 320, the second gas cylinder is used to fill the buffer gas into the three-way glass tube through the second gas outlet pipeline and the connecting pipeline, and the third gas cylinder is used to fill the quenching gas into the three-way glass tube through the second gas outlet pipeline and the connecting pipeline.

[0022] An angular rate sensor comprises a pump light source, a first 45° inclined fiber grating, a birefringent chirped fiber grating, a probe light source, a second 45° inclined fiber grating, a fiber coupler, the alkali metal cell, a fiber filter, a polarization analyzer and a magnetic field generator, the pump light source is connected to a first incident end of the fiber coupler through the first 45° inclined fiber grating and the birefringent chirped fiber grating in sequence, the probe light source is connected to a second incident end of the fiber coupler through the second 45° inclined fiber grating, a first fiber collimator of the alkali metal cell is connected to an exit end of the fiber coupler, and the polarization analyzer is connected to a second fiber collimator of the alkali metal cell through the fiber filter; a polarization direction of the first 45° inclined grating is parallel to a long axis or a short axis of the birefringent chirped fiber grating, and the magnetic field generator is arranged outside the alkali metal cell.

[0023] Further, the angular rate sensor further comprises a non-magnetic heating box and a magnetic shielding box, the non-magnetic heating box is arranged outside the alkali metal cell, and the magnetic shielding box is arranged outside the magnetic field generator.

[0024] The alkali metal cell has the following beneficial effects: the alkali metal cell takes the three-way glass tube as a carrier, is formed by filling the alkali metal atoms and inert gas into the three-way glass tube, and is provided with the first fiber collimator and the second fiber collimator in the first channel and the second channel at opposite ends of the three-way glass tube for the incidence and emission of light beams in the three-way glass tube and alignment, so that the gas cell is miniaturized, high airtightness, high surface shape precision and good inner wall state of the gas cell are ensured, and the release and filling of the alkali metal atoms and inert gas in a vacuum environment are relatively easy. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Structure diagram of alkali metal cell provided by the present application.

[0026] Figure 2 Step block diagram of step 300 in the preparation and filling method of alkali metal cell provided by the present application.

[0027] Figure 3 Step block diagram of step 300 in the preparation and filling method of alkali metal cell provided by the present application.

[0028] Figure 4 Structure principle diagram of the preparation and filling system of alkali metal cell provided by the present application.

[0029] Figure 5 Structure principle diagram of the angular rate gyroscope provided by the present application.

[0030] Figure 6 Structure principle diagram of the pump light path in the angular rate gyroscope provided by the present application. DETAILED DESCRIPTION

[0031] The present application will be described in detail below with reference to the drawings and embodiments, and the examples of the embodiments are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0032] In the description of the present application, it should be understood that the terms “length”, “width”, “upper”, “lower”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”, “outer” and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying 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.

[0033] In addition, the terms “first”, “second”, “third” are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features referred to. 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 “multiple” is two or more, unless otherwise specifically limited.

[0034] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," and "setting," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0035] Example 1

[0036] like Figure 1 As shown, an alkali metal gas chamber based on a three-way glass tube 710 includes a three-way glass tube 710, a first optical fiber collimator 720, and a second optical fiber collimator 730. The three-way glass tube 710 has a first channel 711, a second channel 712, and a third channel 713 that are connected. The first channel 711 and the second channel 712 are in a straight-through structure, while the third channel 713 is not in a straight-through structure with respect to the first channel 711 and the second channel 712. The first optical fiber collimator 720 and the second optical fiber collimator 730 are respectively sealed within the first channel 711 and the second channel 712 of the three-way glass tube 710, and the first optical fiber collimator 720 and the second optical fiber collimator 730 are aligned with each other. The third channel 713 of the three-way glass tube 710 is sealed. The three-way glass tube 710 is filled with at least alkali metal atoms 740 and an inert gas 750.

[0037] The alkali metal gas chamber of the present invention uses the three-way glass tube 710 as a carrier and is formed by filling the three-way glass tube 710 with alkali metal atoms 740 and inert gas 750. The first fiber collimator 720 and the second fiber collimator 730 are respectively arranged in the first channel 711 and the second channel 712 at opposite ends of the three-way glass tube 710 for the entry and exit and alignment of the light beam in the three-way glass tube 710. While realizing the miniaturization of the gas chamber, it can ensure high airtightness, high surface accuracy and good inner wall condition of the gas chamber, and make it easier to release and fill the alkali metal atoms 740 and inert gas 750 in a vacuum environment.

[0038] In this embodiment, the third channel 713 is perpendicular to the first channel 711 and the second channel 712; the first fiber collimator 720 and the second fiber collimator 730 are respectively fixed in the first channel 711 and the second channel 712 of the three-way glass tube 710 by vacuum sealing glue, and respectively seal the first channel 711 and the second channel 712 to increase the air tightness; the third channel 713 of the three-way glass tube 710 is closed by melting after the filling of the alkali metal atoms 740 and the noble gas 750 to achieve a sealed arrangement.

[0039] The first fiber collimator 720 and the second fiber collimator 730 include a self-focusing lens part and a pigtail part, the diameter of the self-focusing lens part is equivalent to the inner diameter of the first channel 711 and the second channel 712 of the three-way glass tube 710, so that the first fiber collimator 720 and the second fiber collimator 730 can be aligned with each other after being inserted into the first channel 711 and the second channel 712 of the three-way glass tube 710 through the self-focusing lens part, without the need for other devices to achieve alignment.

[0040] In use, the first fiber collimator 720 is used for the incidence of pump light and probe light, the second fiber collimator 730 is used for the emission of pump light and probe light, and the first fiber collimator 720 and the second fiber collimator 730 are aligned with each other. The pump light is circularly polarized light, and the probe light is linearly polarized light. The pump light excites the electron spin polarization of the alkali metal atoms 740 in the three-way glass tube 710, and the alkali metal atoms 740 cause the nuclear spin polarization of the noble gas 750 through the spin exchange collision mechanism. Under a static magnetic field, the nuclear spin polarized noble gas 750 will precess around the static magnetic field, and the precession frequency is related to the static magnetic field. When the angular rate sensor rotates around the static magnetic field with the carrier, the precession frequency of the nuclear spin of the noble gas 750 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 further cause the polarization state of the probe light to change. By analyzing the change of the polarization state of the probe light, the angular rate of the angular rate sensor can be calculated.

[0041] Preferably, the three-way glass tube 710 is also filled with at least one of a buffer gas 760 (noble gas without nuclear spin) and a quenching gas 770 (diatomic molecule).

[0042] The buffer gas 760 is used to collide with the alkali metal atoms 740 to reduce the collision between the alkali metal atoms 740 and the wall of the three-way glass tube 710, thereby reducing the depolarization rate of the alkali metal atoms 740 and reducing the photon energy required for the polarization of the alkali metal atoms 740, thus increasing the polarizability of the alkali metal atoms 740. The quenching gas 770 is used to absorb the resonant photons spontaneously emitted when the alkali metal atoms 740 recover from the excited state to the ground state, so as to avoid the resonant photons causing other alkali metal atoms 740 to jump back from the ground state to the excited state and cause depolarization, thereby reducing the depolarization rate of the alkali metal atoms 740.

[0043] The alkali metal atom 740 may be, but is not limited to, cesium (Cs) or rubidium (Rb) atoms, and the inert gas 750 may be, but is not limited to, xenon, neon, or helium. 3 The buffer gas 760 may be, but is not limited to, helium (He), etc. 4 The quenching gas 770 may be, but is not limited to, nitrogen.

[0044] Example 2

[0045] like Figure 2 As shown, a method for preparing and filling an alkali metal gas chamber is provided for preparing and filling the alkali metal gas chamber described in Example 1; the preparation and filling method includes the following steps:

[0046] Step 100: Provide a three-way glass tube 710, the three-way glass tube 710 having a first channel 711, a second channel 712 and a third channel 713 that are connected, the first channel 711 and the second channel 712 having a straight-through structure, and the third channel 713 having a non-straight-through structure with the first channel 711 and the second channel 712.

[0047] In step 100, the third channel 713 is perpendicular to the first channel 711 and the second channel 712.

[0048] Step 200: Provide a first fiber optic collimator 720 and a second fiber optic collimator 730, and seal the first fiber optic collimator 720 and the second fiber optic collimator 730 in the first channel 711 and the second channel 712 of the three-way glass tube 710, respectively.

[0049] In step 200, the first fiber collimator 720 and the second fiber collimator 730 are respectively bonded and fixed to the first channel 711 and the second channel 712 of the three-way glass tube 710 by vacuum sealant, and the first channel 711 and the second channel 712 are sealed respectively.

[0050] Step 300: At least alkali metal atoms 740 and inert gas 750 are filled into the three-way glass tube 710 through the third channel 713.

[0051] In this step 300, a preparation and filling system is used to fill at least alkali metal atoms 740 and inert gas 750 into the three-way glass tube 710 through the third channel 713. As shown in Figure 4 the preparation and filling system includes a vacuum pump 13, an alkali metal container 14, an alkali metal heater 15, a first gas bottle 16 and a connecting pipeline 19, the vacuum pump 13 is connected with the connecting pipeline 19 through a suction pipeline 20, the alkali metal container 14 is connected with the connecting pipeline 19 through an alkali metal pipeline 21, the first gas bottle 16 is connected with the connecting pipeline 19 through a first gas outlet pipeline 22, and the connecting pipeline 19 is connected with the third channel 713 of the three-way glass tube 710; the first gas bottle 16 is filled with the inert gas 750, the alkali metal container 14 contains an alkali metal releasing agent 25, and the alkali metal heater 15 is used to heat the alkali metal releasing agent 25 in the alkali metal container 14.

[0052] In this embodiment, the connecting pipeline 19 is fixed in the third channel 713 of the three-way glass tube 710 by vacuum sealing adhesive bonding to increase the air tightness of the connection.

[0053] Preferably, in step 300, at least one of buffer gas 760 and quenching gas 770 is also filled into the three-way glass tube 710 through the third channel 713. The preparation and filling system further includes at least one of a second gas bottle 17 and a third gas bottle 18, the second gas bottle 17 is connected with the connecting pipeline 19 through a second gas outlet pipeline 23, and the third gas bottle 18 is connected with the connecting pipeline 19 through a third gas outlet pipeline 24; the second gas bottle 17 is filled with buffer gas 760, and the third gas bottle 18 is filled with quenching gas 770.

[0054] In step 300, as shown in Figure 3 the preparation and filling system is used to fill at least alkali metal atoms 740 and inert gas 750 into the three-way glass tube 710 through the third channel 713. As shown in

[0055] Step 310: The vacuum pump 13 is used to vacuumize the three-way glass tube 710 through the suction pipeline 20 and the connecting pipeline 19, so that the vacuum degree of the three-way glass tube 710 reaches a preset value.

[0056] In this step 310, the vacuum gauge 25 and the stop valve 26 are arranged in the exhaust pipeline 20. First, the stop valve 26 is closed to disconnect the exhaust pipeline 20 from the inside of the connecting pipeline 19, then the vacuum pump 13 is started to begin vacuumizing, and then the stop valve 26 is opened to connect the exhaust pipeline 20 to the inside of the connecting pipeline 19. The vacuum pump 13 vacuumizes the three-way glass tube 710 through the exhaust pipeline 20 and the connecting pipeline 19. During vacuumizing, the vacuum degree in the exhaust pipeline 20 is monitored by the vacuum gauge 25. When the vacuum degree reaches the preset value, the stop valve 26 is first closed to disconnect the exhaust pipeline 20 from the inside of the connecting pipeline 19, and then the vacuum pump 13 is turned off to stop vacuumizing.

[0057] Step 320: The first gas cylinder 16 is used to fill the inert gas 750 into the three-way glass tube 710 through the first gas outlet pipeline 22 and the connecting pipeline 19.

[0058] In this step 320, the first gas outlet valve 28 is arranged in the first gas outlet pipeline 22. First, the first gas outlet valve 28 is closed to disconnect the first gas outlet pipeline 22 from the inside of the connecting pipeline 19, then the first gas cylinder 16 is opened to begin filling, and then the first gas outlet valve 28 is opened to connect the first gas outlet pipeline 22 to the inside of the connecting pipeline 19. The inert gas 750 naturally diffuses into the three-way glass tube 710 along the first gas outlet pipeline 22 and the connecting pipeline 19. When the three-way glass tube 710 is filled with the inert gas 750, the first gas outlet valve 28 is first closed to disconnect the first gas outlet pipeline 22 from the inside of the connecting pipeline 19, and then the first gas cylinder 16 is turned off to stop filling.

[0059] Preferably, at the same time, the second gas cylinder 17 is used to fill the buffer gas 760 into the three-way glass tube 710 through the second gas outlet pipeline 23 and the connecting pipeline 19, and the third gas cylinder 18 is used to fill the quenching gas 770 into the three-way glass tube 710 through the second gas outlet pipeline 23 and the connecting pipeline 19.

[0060] The second gas outlet pipeline 23 and the third gas outlet pipeline 24 are respectively provided with a second gas outlet valve 29 and a third gas outlet valve 30. The second gas outlet valve 29 and the third gas outlet valve 30 are closed first to disconnect the second gas outlet pipeline 23 and the third gas outlet pipeline 24 from the connecting pipeline 19. Then the second gas cylinder 17 and the third gas cylinder 18 are opened to fill gas. Then the second gas outlet valve 29 and the third gas outlet valve 30 are opened to connect the second gas outlet pipeline 23 and the third gas outlet pipeline 24 to the connecting pipeline 19. The buffer gas 760 diffuses along the second gas outlet pipeline 23 and the connecting pipeline 19, and the quenching gas 770 diffuses along the third gas outlet pipeline 24 and the connecting pipeline 19 into the three-way glass tube 710. When the three-way glass tube 710 is filled with the buffer gas 760 and the quenching gas 770, the second gas outlet valve 29 and the third gas outlet valve 30 are closed first to disconnect the second gas outlet pipeline 23 and the third gas outlet pipeline 24 from the connecting pipeline 19. Then the second gas cylinder 17 and the third gas cylinder 18 are turned off to stop filling gas.

[0061] Most preferably, the first gas outlet pipeline 22, the second gas outlet pipeline 23 and the third gas outlet pipeline 24 are respectively provided with a first gas flow meter 31, a second gas flow meter 32 and a third gas flow meter 33 to control the gas flow of the inert gas 750, the buffer gas 760 and the quenching gas 770 respectively during filling. The flow rates of the first gas flow meter 31, the second gas flow meter 32 and the third gas flow meter 33 are set to control the mixing ratio of the inert gas 750, the buffer gas 760 and the quenching gas 770.

[0062] Step 330: The alkali metal heater 15 is used to heat the alkali metal releasing agent 25 in the alkali metal container 14 to release alkali metal atoms 740, which are filled into the three-way glass tube 710 through the alkali metal pipeline 21 and the connecting pipeline 19.

[0063] In this step 330, the alkali metal valve 27 in the alkali metal pipeline 21 is closed first to disconnect the alkali metal pipeline 21 from the inside of the connecting pipeline 19, and then the alkali metal heater 15 is used to heat the alkali metal releasing agent 25 in the alkali metal container 14 to make the temperature of the alkali metal releasing agent 25 reach its gasification temperature, so that the alkali metal releasing agent 25 is gasified to release the alkali metal atoms 740, and then the alkali metal valve 27 is opened to connect the alkali metal pipeline 21 with the inside of the connecting pipeline 19, so that the alkali metal atoms 740 diffuse naturally along the alkali metal pipeline 21 and the connecting pipeline 19 into the three-way glass tube 710, when the three-way glass tube 710 is filled with the alkali metal atoms 740, the alkali metal valve 27 is closed first to disconnect the alkali metal pipeline 21 from the inside of the connecting pipeline 19, and then the alkali metal heater 15 is turned off or removed to stop heating the alkali metal releasing agent 25 in the alkali metal container 14.

[0064] Step 400: The third passage 713 of the three-way glass tube 710 is sealed.

[0065] In this step 400, the hydrogen-oxygen flame torch 34 is used to heat the position below the third passage 713 connected with the connecting pipeline 19 of the preparation and filling system, so that the third passage 713 is melted at the heated position, and then slowly stretched or rotated, so that the diameter of the third passage 713 at the melted position is gradually reduced by the slow stretching or rotating process, so that the third passage 713 is disconnected at the melted position and sealed to achieve sealing arrangement, or the third passage 713 is clamped and sealed at the melted position and then disconnected.

[0066] Example Three

[0067] As Figure 5 and 6As shown, an angular rate sensor comprises a pump light source 1, a first 45° tilted fiber grating 2, a birefringent chirped fiber grating 3, a probe light source 4, a second 45° tilted fiber grating 5, a fiber coupler 6, the alkali vapor cell 7 described in embodiment one, a fiber filter 8, a polarization analyzer 9 and a magnetic field generator 10, the pump light source 1 is connected to the first incident end of the fiber coupler 6 through the first 45° tilted fiber grating 2 and the birefringent chirped fiber grating 3 in sequence, the probe light source 4 is connected to the second incident end of the fiber coupler 6 through the second 45° tilted fiber grating 5, the first fiber collimator 720 of the alkali vapor cell 7 is connected to the exit end of the fiber coupler 6, and the polarization analyzer 9 is connected to the second fiber collimator 730 of the alkali vapor cell 7 through the fiber filter 8; the polarization direction of the first 45° tilted grating is parallel to the long axis or short axis of the birefringent chirped fiber grating 3, and the magnetic field generator 10 is arranged outside the alkali vapor cell 7.

[0068] The angular rate sensor of the present application adopts the first 45° tilted fiber grating 2 and the birefringent chirped fiber grating 3 as the pump light path at the front end, adopts the second 45° tilted fiber grating 5 as the probe light path, and mixes the pump light and the probe light through the fiber coupler 6 and then couples them into the alkali vapor cell 7, and adopts the fiber filter 8 as the light exit path at the rear end to filter the pump light emitted by the alkali vapor cell 7, and only provides the probe light emitted by the alkali vapor cell 7 to the polarization analyzer 9 for demodulation, and the pump light path, the probe light path and the light exit path are all integrated on the fiber, which greatly improves the integration of the angular rate sensor, realizes the miniaturization of the angular rate sensor, and the fiber has the advantages of strong anti-electromagnetic interference ability, acid and alkali corrosion resistance, electrical insulation, high measurement precision, high reliability, long service life and the like, and has greater competitive advantage in strong electromagnetic interference and other harsh environments.

[0069] The pump light source 1 is used to emit pump light, which is converted into circularly polarized light after passing through the first 45° tilted fiber grating 2 and the birefringent chirped spiral fiber grating 3 in turn, and then is incident into the alkali metal cell 7 to cause the electron spin polarization of the alkali metal atoms 740 and the nuclear spin polarization of the noble gas 750; the probe light source 4 is used to emit probe light, which is converted into linearly polarized light after passing through the second 45° tilted fiber grating 5, and then is incident into the alkali metal cell 7 to be modulated by the noble gas 750 of the nuclear spin polarized noble gas 750; the fiber coupler 6 is used to mix the pump light and the probe light and then couple them into the alkali metal cell 7; the fiber filter 8 is used to filter out the pump light in the mixed light emitted by the alkali metal cell 7, and only keep the probe light in the mixed light; the polarization analyzer 9 is used to collect and process the probe light emitted by the alkali metal cell 7 to obtain the polarization state of the probe light and calculate the angular rate of the angular rate sensor; the magnetic field generator 10 is used to provide static magnetic fields in X, Y and Z directions for the alkali metal cell 7 to make the nuclear spin polarized noble gas 750 precess around the static magnetic field at the Larmor frequency.

[0070] The optical frequency of the pump light is the same as the natural frequency of the alkali metal atoms 740, so that the pump light can resonate with the alkali metal atoms 740 to cause the electron spin polarization of the alkali metal atoms 740. The optical frequency of the probe light is far away from the natural frequency of the alkali metal atoms 740 as much as possible, so as not to affect the electron spin polarization of the alkali metal atoms 740.

[0071] The grating writing plane of the first 45° tilted fiber grating 2 is arranged at an angle of 45° with the fiber axis, which can almost completely leak the p-polarized light in the pump light to the outside of the fiber, and almost completely keep the s-polarized light in the pump light to be transmitted in the fiber, thereby converting the pump light into linearly polarized light; the birefringent chirped spiral fiber grating 3 is based on the birefringence effect, and the chirped spiral structure can cause different degrees of phase delay of the linearly polarized light. When the polarization direction of the first 45° tilted fiber grating 2 is parallel to the long axis or the short axis of the grating of the birefringent chirped spiral fiber grating 3, the birefringent chirped spiral fiber grating 3 can cause different degrees of phase delay of the linearly polarized light output by the first 45° tilted fiber grating 2, and the linearly polarized light with different phase delays is mixed to finally form circularly polarized light.

[0072] The polarization direction of the first 45°-inclined fiber grating 2 can be parallel to the long axis of the birefringent chirped spiral fiber grating 3 or parallel to the short axis of the birefringent chirped spiral fiber grating 3, and there is no substantial difference in performance and function in converting linearly polarized light into circularly polarized light.

[0073] The grating period of the birefringent chirped spiral fiber grating 3 gradually decreases along the light transmission direction, and the minimum grating period of the birefringent chirped spiral fiber grating 3 is not less than the grating period of the first 45°-inclined fiber grating 2, so as to achieve good circular polarization conversion effect.

[0074] The first 45°-inclined fiber grating 2, the second 45°-inclined fiber grating 5 and the birefringent chirped spiral fiber grating 3 can be made of single-mode fiber, and in order to maintain the polarization state of the probe light and the pump light during transmission, the first 45°-inclined fiber grating 2, the second 45°-inclined fiber grating 5 and the birefringent chirped spiral fiber grating 3 can also be made of polarization-maintaining fiber in the embodiment.

[0075] Considering that it is difficult to make a 45°-inclined fiber grating by using polarization-maintaining fiber, and the birefringent chirped spiral fiber grating 3 needs large birefringence and polarization maintaining capability, preferably, the first 45°-inclined fiber grating 2 and the second 45°-inclined fiber grating 5 are made of single-mode fiber, and the birefringent chirped spiral fiber grating 3 is made of polarization-maintaining fiber.

[0076] Most preferably, the birefringent chirped spiral fiber grating 3 is made of an elliptical core fiber, so that the birefringent chirped spiral fiber grating 3 forms an elliptical core chirped spiral fiber grating. The elliptical core fiber is a special polarization-maintaining fiber, and its core cross section is elliptical instead of the traditional circular shape. The elliptical core structure can give the elliptical core fiber large birefringence and polarization maintaining capability.

[0077] The grating period of the birefringent chirped spiral fiber grating 3 gradually decreases along the light transmission direction, and the minimum grating period of the birefringent chirped spiral fiber grating 3 is not less than the grating period of the first 45°-inclined fiber grating 2, so as to achieve good circular polarization conversion effect.

[0078] The angular rate sensor further comprises a non-magnetic heating box 11 and a magnetic shielding box 12. The non-magnetic heating box 11 is arranged outside the alkali metal cell 7 to increase the number density of the alkali metal atoms 740 and improve the detection accuracy of the angular rate. The magnetic shielding box 12 is arranged outside the magnetic field generator 10 to isolate external magnetic fields and reduce the disturbance of external magnetic fields on spin polarization.

[0079] Finally, it should be noted that the above examples are intended to illustrate the technical solutions of the embodiments of the present application but not to limit them, and although the embodiments of the present application 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 present application can still be modified or equivalently replaced, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An angular rate sensor, characterized in that, The device includes a pump source, a first 45° tilted fiber grating, a birefringent chirped spiral fiber grating, a probe source, a second 45° tilted fiber grating, a fiber coupler, an alkali metal gas chamber, a fiber filter, a polarization analyzer, and a magnetic field generator. The alkali metal gas chamber includes a three-way glass tube, a first fiber collimator, and a second fiber collimator. The three-way glass tube has a first channel, a second channel, and a third channel that are connected. The first channel and the second channel are connected in a straight-through structure, while the third channel is not connected to the first channel and the second channel. The first fiber collimator and the second fiber collimator are respectively sealed in the first channel and the second channel of the three-way glass tube, and the first fiber collimator and the second fiber collimator are aligned with each other; the third channel of the three-way glass tube is sealed, and the three-way glass tube is filled with at least alkali metal atoms and inert gas; The pump light source is connected to the first incident end of the fiber coupler via the first 45° tilted fiber grating and the birefringent chirped spiral fiber grating in sequence. The detection light source is connected to the second incident end of the fiber coupler via the second 45° tilted fiber grating. The first fiber collimator of the alkali metal gas cell is connected to the output end of the fiber coupler. The polarization analyzer is connected to the second fiber collimator of the alkali metal gas cell via the fiber filter. The polarization direction of the first 45° tilted fiber grating is parallel to the major axis or minor axis of the birefringent chirped spiral fiber grating. The magnetic field generator is located outside the alkali metal gas cell. The first 45° tilted fiber grating and the birefringent chirped spiral fiber grating are used to convert the pump light emitted by the pump source into circularly polarized light; The second 45° tilted fiber grating is used to convert the probe light emitted by the probe light source into linearly polarized light; The fiber optic coupler is used to mix the pump light and the probe light and couple them into the alkali metal gas chamber; The fiber optic filter is used to filter out the pump light in the mixed light emitted from the alkali metal gas cell, while retaining only the probe light in the mixed light for demodulation by the polarization analyzer.

2. The angular rate sensor according to claim 1, characterized in that, The three-way glass tube is also filled with at least one of a buffer gas and a quenching gas.

3. The angular rate sensor according to claim 1, characterized in that, The angular rate sensor also includes a non-magnetic heating box and a magnetic shielding box. The non-magnetic heating box is located outside the alkali metal gas chamber, and the magnetic shielding box is located outside the magnetic field generator.

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