Compound atomic interferometer optical system

Abstract

The application discloses a kind of composite atomic interferometer optical path systems, belong to quantum precision measurement technical field.The system is connected with three external cavity semiconductor lasers, respectively generate first laser, second laser and third laser.The first laser is frequency-locked as frequency reference by frequency modulation spectrum, the second laser keeps fixed frequency difference with the first laser, and the third laser keeps fixed frequency difference with the second laser.The system prepares blow-off light, cooling light, probe light, Raman light and Bragg light by AOM frequency shift, and switches the output of Raman light and Bragg light by mechanical shutter.The application integrates Raman and Bragg atomic interference functions, supports two working modes: one is Bragg interference combined with Raman spectrum detection, which improves the interference contrast;The second is Bragg large momentum transfer combined with Raman interference, which improves the measurement sensitivity.The system structure is compact, and the utilization rate of optical device is high, which is beneficial to the miniaturization and mobility of atomic interferometer.

Description

Technical Field

[0001] This invention belongs to the field of quantum precision measurement technology, and specifically relates to an optical path system for a composite atomic interferometer. Background Technology

[0002] In the field of quantum precision measurement, cold atom interferometry has become one of the important methods for high-precision gravity measurement. Gravimeters based on atomic interferometry have the advantages of potential high sensitivity and long-term stable operation, and have broad application prospects in fields such as basic physics research, geophysical exploration, and inertial navigation.

[0003] Currently, atomic interferometers are mainly divided into two categories: Raman atomic interferometers and Bragg atomic interferometers. Raman atomic interferometers achieve coherent manipulation of atomic internal states based on stimulated Raman transitions, possessing high interference contrast and mature detection schemes, and have been widely used in the field of gravity measurement. However, the atomic internal states in Raman atomic interferometers change during the interference process, and fluctuations in the external electromagnetic field can easily interfere with the interference phase, affecting measurement accuracy.

[0004] Bragg-type atomic interferometers utilize Bragg diffraction to coherently manipulate the momentum states of atoms. Atoms maintain the same internal state throughout the interference process, thus naturally suppressing optical frequency shifts and ambient electromagnetic noise. In recent years, researchers have successfully implemented high-sensitivity atomic gravimeters based on Bragg diffraction and conducted fundamental physics research such as Lorentz symmetry testing. However, traditional Bragg interferometers have limitations in detecting the final states of atoms: because the internal states of atoms remain unchanged during Bragg diffraction, it is difficult to effectively distinguish different momentum states using conventional fluorescence detection methods, which limits further improvement in interference fringe contrast.

[0005] To address the detection challenges of Bragg interferometers, current research has proposed a technique for detecting atomic momentum state distributions using Raman spectroscopy. This technique selectively transfers atoms in different momentum states to different internal states via resonant Raman pulses, achieving high-contrast detection of momentum states. Furthermore, large momentum transfer techniques have been extensively studied to improve the sensitivity of atomic interferometers. Researchers have achieved large momentum transfer based on Bragg diffraction and Raman transitions, respectively, and have extended momentum transfer to tens or even hundreds of photon back impulses using methods such as sequential pulses.

[0006] However, existing technologies have the following shortcomings: First, while the aforementioned Bragg interferometry, Raman detection, and high momentum transfer techniques have been reported in principle, existing published literature mainly focuses on theoretical schemes or experimental results, lacking a complete description of specific optical systems capable of simultaneously realizing these functions. Existing patents, such as "A Time-Division Multiplexing Optical Path System for an Atomic Interferometer" (CN116989760A), propose a time-division multiplexing optical path design concept, but its optical path structure differs significantly from this invention and does not involve the combined application of Bragg and Raman beams.

[0007] Second, the optical systems of existing atomic interferometers are typically optimized for a single operating mode (pure Raman or pure Bragg). If switching between different operating modes is required within the same device, the optical path often needs to be reconfigured or optical components replaced, which is detrimental to the integration and miniaturization of the instrument.

[0008] Third, existing optical systems typically use multiple independent lasers to generate lasers with different functions, making the system complex and bulky. Furthermore, the beat frequency locking between multiple lasers is easily affected by external environmental disturbances, which is not conducive to the long-term stable operation of the atomic interferometer.

[0009] Therefore, how to design a compact composite atomic interferometer optical system that can flexibly switch between Bragg and Raman interferometry and supports large momentum transfer is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0010] This invention addresses the aforementioned problems by proposing a composite atomic interferometer optical path system. The concept involves connecting three external cavity semiconductor lasers (ECDLs) as the light source for the optical system. Frequency modulation spectroscopy (FMS) locks the first ECDL1 as the reference laser, outputting a first laser F1. The second ECDL2 determines its frequency by beating ECDL1 and outputs a second laser F2. The third ECDL3 determines its frequency by beating ECDL2 and outputs a third laser F3. Atomically shifted beams (AOMs) to specific frequencies are then used to prepare blown-out light, cooling light, probe light, Raman light, and Bragg light. Finally, a mechanical shutter is used to control the output time of the Raman and Bragg lights, thereby realizing different types of atomic interferometers.

[0011] The optical path system of the composite atomic interferometer of the present invention includes a first optical path and a second optical path; The first optical path collimates the first laser F1 and splits it into a first functional base beam, a first beat frequency beam, a second functional base beam, and a locked beam; The second optical path collimates the second laser F2 and splits it into a second beat frequency beam and a third functional base beam; the third functional base beam and the first functional base beam are combined and then split into a Raman light base beam and a fourth functional base beam. The spectral locking branch performs frequency modulation and spectral stabilization based on the locked beam, and provides feedback to lock the frequency of the first laser F1. The beat frequency monitoring branch combines the first beat frequency beam and the second beat frequency beam and inputs them into a high-speed photoelectric probe to realize beat frequency signal monitoring. The functional optical path receives the fourth functional substrate beam and the second functional substrate beam and generates blow-off light, cooling light and probe light; The Raman light preparation branch receives the Raman substrate beam, generates Raman light, and transmits it to the interference light output end; The Bragg beam preparation branch uses the third laser F3 as input to generate Bragg beams, which are then input to the interference beam output terminal. The interference light output terminal can be switched to output Bragg light or Raman light; The first laser F1 and the second laser F2 maintain a fixed frequency difference, and the third laser F3 and the second laser F2 maintain a fixed frequency difference.

[0012] When combined with an actual atomic interference chamber, the interference light output end is connected to the interference region of the external atomic interferometer chamber; the cooling light is guided to the preparation region of the external atomic interferometer chamber, and the probe light is guided to the probe region of the external atomic interferometer chamber; the blow-off light is guided between the interference region and the probe region.

[0013] Preferably, the first optical path includes a first laser collimator 110. After being collimated by the first laser collimator 110, the first laser passes sequentially through a first Glan Taylor prism 111 and a first half-glass slide 112 before reaching a first polarizing beam splitter 113, where it is split into a first reflected light and a first transmitted light. The first reflected light passes through a second half-glass slide 121 and a first mechanical shutter 124 before being output as a first functional base beam. The first transmitted light passes through a third half-glass slide 114 and enters a second polarizing beam splitter 115, where it is split into a first beat frequency beam and a locked base beam. The first beat frequency beam passes through a fourth half-glass slide 122 in a direction perpendicular to the first transmitted light and enters the beat frequency monitoring branch. The locked base beam exits in the direction of the first transmitted light, passes through a fifth half-glass slide 116, and enters a third polarizing beam splitter 117, where it is split into a locked beam and a second functional base beam. The second functional base beam is emitted in a direction perpendicular to the locking base beam, and passes through the second optical wedge 123 and the second mechanical shutter 137 in sequence to enter the functional optical path; The locked beam is emitted along the direction of the locked substrate beam, passes through the first optical wedge 118, the first composite glass plate 119 and the second laser collimator 120 and enters the fiber electro-optic modulator FEOM; the fiber electro-optic modulator FEOM outputs the locked beam to the spectral locking branch.

[0014] Preferably, the second optical path includes a third laser collimator 140; The third laser collimator 140 collimates the second laser F2 and emits it to the first reflector 139; After being reflected by the first mirror 139, the second laser F2 passes through the first optical isolator 138 and the sixth half-glass slide 137 in sequence before entering the fourth polarization beam splitter 136, splitting into a second beat frequency beam and a third functional substrate beam. The second beat frequency beam is reflected by the second reflector 125 and passes sequentially through the sixth half glass plate 126 and the third optical wedge 127 before entering the beat frequency monitoring branch. The third functional substrate beam passes through the third mechanical shutter 135 and enters the fifth polarization beam splitter 141, where it is combined with the first functional substrate beam. It exits along the direction of the first functional substrate beam, passes through the seventh half-glass slide 142, and arrives at the sixth polarization beam splitter 143, where it is split into a Raman light substrate beam and a fourth functional substrate beam. The Raman light substrate beam exits along the incident direction to the Raman light preparation branch, while the fourth functional substrate beam exits along the direction perpendicular to the incident direction to the functional light path.

[0015] Preferably, the beat frequency monitoring branch includes a seventh polarization beam splitter 128; the first beat frequency beam and the second beat frequency beam enter the seventh polarization beam splitter 128 and are combined, and are emitted along the direction of the second beat frequency beam, passing through the eighth half-glass slide 129, the eighth polarization beam splitter 130, the third focusing lens 131 and the fourth optical wedge 132 in sequence before arriving at the high-speed photoelectric probe 133, thereby realizing beat frequency signal monitoring.

[0016] Preferably, the input of the functional optical path is the fourth functional base beam and the second functional base beam; the fourth functional base beam passes through the first acousto-optic modulator 146 and the eighth half-glass slide 147 in sequence and then enters the ninth polarization beam splitter 148, splitting the beam into a blow-off light base beam and a cooling detection base beam. The blown-off light base beam is emitted in a direction perpendicular to the fourth functional beam. After being reflected by the third reflecting mirror 149, it passes through the fourth mechanical shutter 150, the fifth optical wedge 151, and the second composite glass plate 152 in sequence, and is then output as blown-off light by the fourth laser collimator 153. The cooling probe base beam is emitted along the direction of the fourth functional base beam, passes through the ninth half-glass plate 155 and the sixth optical wedge 156 in sequence, and then enters the ninth polarization beam splitter 157; the second functional base beam passes through the twelfth glass plate 154 and then enters the ninth polarization beam splitter 157, where it is combined with the fourth functional beam and split into a cooling light base beam and a probe light base beam that are perpendicular to each other. The cooling light substrate beam is emitted along the direction of the fourth functional substrate beam, passes sequentially through the fifth mechanical shutter 158, the eleventh and eleventh half glass plate 159, the tenth polarization beam splitter 160, the seventh optical wedge 161 and the third composite glass plate 162, and is collimated by the fifth laser collimator 163 to generate cooling light. The probe light base beam is emitted along the direction of the second functional base beam. After being reflected by the fourth reflector 164, it passes sequentially through the 1 / 2 twelfth glass plate 165, the sixth mechanical shutter 166, the eleventh polarization beam splitter 167, the eighth optical wedge 168, and the fourth composite glass plate 169. Finally, it is collimated by the sixth laser collimator 170 to generate the probe light.

[0017] Preferably, the spectral locking branch includes a seventh laser collimator 101, which collimates and emits the locking beam. The locking beam passes sequentially through the second light blocker 102, the thirteenth half-glass slide 103, the twelfth polarization beam splitter 104, the first focusing lens 105, the second focusing lens 106, the ninth optical wedge 107, the rubidium chamber, and the fourteenth half-glass slide 108 before reaching the fifth reflecting mirror 109 and being reflected in the opposite direction. The reflected locking beam is reflected by the twelfth polarization beam splitter 104 and then enters the first photodiode 206, where it is collected by an external collector. The external collector locks the frequency of the first laser F1 based on the reflected locking beam.

[0018] Preferably, the input to the Raman light preparation branch is a Raman light substrate beam. The Raman light substrate beam passes sequentially through the seventh mechanical shutter 144 and the fourteenth half-glass slide 145 and then enters the thirteenth polarization beam splitter 175. After being reflected by the thirteenth polarization beam splitter 175, it exits at an angle perpendicular to the incident direction and passes sequentially through the tenth optical wedge 176, the second electro-optic modulator 177, the fifteenth half-glass slide 178, and the fourth focusing lens 179. After being reflected by the sixth reflecting mirror 180, it passes sequentially in the opposite direction through the fourth focusing lens 179, the fifteenth half-glass slide 178, the second electro-optic modulator 177, the tenth optical wedge 176, the thirteenth polarization beam splitter 175, the fourteenth polarization beam splitter 174, the eleventh optical wedge 173, and the fifth composite glass slide 172. Finally, it is collimated into Raman light by the eighth laser collimator 171 and output to the interference light output end.

[0019] Preferably, the input to the Bragg beam preparation branch is the third laser F3; the third laser is collimated by the ninth laser collimator 205, reflected by the seventh mirror 204, and emitted at an angle perpendicular to the incident direction. After passing through the sixteenth half glass plate 203, it enters the fifteenth polarization beam splitter 202 and is split into the fifth functional substrate light and the sixth functional substrate light. The fifth functional substrate beam exits along the direction of the third laser incident on the fifteenth polarization beam splitter 202, and after passing through the sixteenth polarization beam splitter 201 and the third acousto-optic modulator 200, it diffracts into the first zeroth order laser and the first first order electro-optic beam. The first zeroth order laser beam is emitted along the incident direction and passes through the central region of the fifth focusing lens 199 before being absorbed by the first baffle 198. The first-stage laser deviates from the direction of the third laser incident on the fifteenth polarization beam splitter 202 and exits sequentially through the off-axis region of the fifth focusing lens 199, the first quarter glass plate 197, and is then reflected by the eighth reflecting mirror 196. It then passes sequentially through the first quarter glass plate 197, the fifth focusing lens 199, and the third acousto-optic modulator 200 in the opposite direction before entering the sixteenth polarization beam splitter 201 and exiting in a direction perpendicular to the fifth functional substrate beam to the seventeenth polarization beam splitter 185. The sixth functional base beam is emitted in a direction perpendicular to the direction of the third laser incident on the fifteenth polarization beam splitter 202. After passing through the seventeenth half glass plate 195, it is reflected by the ninth mirror 194 and emitted at an angle perpendicular to the incident direction. After passing through the eighteenth polarization beam splitter 193 and the fourth acousto-optic modulator 192, it is diffracted into the second zeroth order laser and the second first order electro-optic beam. The second zeroth order laser is emitted along the incident direction, passes through the central region of the sixth focusing lens 191 and is absorbed by the second baffle 190. The second-stage laser beam deviates from the incident direction and passes sequentially through the off-axis region of the sixth focusing lens 191 and the second quarter glass plate 189. After being reflected by the ninth reflecting mirror 188, it passes sequentially through the second quarter glass plate 189, the sixth focusing lens 191, and the fourth acousto-optic modulator 192 in the opposite direction before entering the eighteenth polarization beam splitter 193. It then exits in a direction perpendicular to the sixth functional base beam to the tenth reflecting mirror 187, exits in a direction perpendicular to the incident direction, passes through the eighteenth half glass plate 186, and is then combined with the first-stage laser beam to form the Bragg base beam. After passing through the eighth mechanical shutter 184 and the fifth acousto-optic modulator 183, the Bragg light substrate light is diffracted into a third zeroth-order laser and a third first-order electro-optic light along the incident direction. The third zeroth-order laser is absorbed by the third baffle 182, and the third first-order electro-optic light passes through the tenth laser collimator 181 and is collimated into Bragg light, and then output to the interference output end.

[0020] Preferably, the first laser F1 is generated by an external first external cavity semiconductor laser; the external second external cavity semiconductor laser determines the frequency of the first laser F1 by beating the frequency with the first external cavity semiconductor laser and generates a second laser F2 that maintains a fixed frequency difference with the first laser F1; the external third external cavity semiconductor laser determines the frequency of the second laser F2 by beating the frequency with the second external cavity semiconductor laser and generates a third laser F3 that maintains a fixed frequency difference with the second laser F2.

[0021] The optical path system of the composite atomic interferometer includes two modes of use: one is to use Bragg light to interfere with atoms and use Raman spectroscopy to detect the distribution of momentum states of atoms after interference, thereby improving contrast; the other is to first use Bragg light to apply a large momentum transfer to atoms, and then use Raman light to complete the interference process.

[0022] The specific steps for interfering with atoms using Bragg light and then probing the distribution of momentum states of the atoms after interference using Raman spectroscopy are as follows: A1. Open the first optical path, the second optical path, and the Raman light preparation optical path; the spectral locking branch locks the frequency of the first laser F1 through frequency modulation spectrum.

[0023] A2. The functional optical path generates cooling light, blowing light, and probe light and guides them to the external atomic interference chamber for cooling and initial state preparation of the magneto-optical trap (MOT) of atoms.

[0024] A3. Close the seventh mechanical shutter 144 in the Raman light preparation branch to prevent Raman light output; open the eighth mechanical shutter 184 in the Bragg light preparation branch; after frequency shifting, beam combining and filtering, the third laser F3 is collimated by the tenth laser collimator 181 to generate Bragg light output to the interference light output end.

[0025] A4. A π / 2-π-π / 2 pulse sequence is applied to atoms using Bragg light to achieve atomic interference; the atoms maintain the same internal state throughout the process, avoiding light frequency shift and electromagnetic field noise.

[0026] A5. When an atom enters the detection region, before the atom reaches the first detection window, the seventh mechanical shutter 144 is briefly opened to apply a resonant Raman π pulse and detect one of the interference output states. Before the atom reaches the second detection window, the seventh mechanical shutter 144 is opened again to apply a second resonant Raman π pulse and detect the other interference output state. Through the above two Raman detections, the complete probability distribution of the two output states is obtained.

[0027] A6. Calculate the contrast of the interference fringes based on the detection signal to infer the gravity or phase information.

[0028] The specific steps for applying a large momentum transfer to atoms using Bragg light, followed by using Raman light to complete the interference process, are as follows: B1. Open the first optical path, the second optical path, and the Raman light preparation optical path; the spectral locking branch locks the frequency of the first laser F1 through frequency modulation spectrum.

[0029] B2. The functional optical path generates cooling light, blowing light, and probe light and guides them to the external atomic interference chamber for magneto-optical trap cooling and initial state preparation of atoms.

[0030] B3. Close the seventh mechanical shutter 144; open the eighth mechanical shutter 184; adjust the Bragg light frequency difference through the third acousto-optic modulator 200 and the fourth acousto-optic modulator 192 to apply multiple Bragg diffraction pulses to the atoms, achieving a large momentum transfer. In this process, the atoms gain a large vertical momentum, increasing the interferometer area.

[0031] B4. Close the eighth mechanical shutter 184 and open the seventh mechanical shutter 144; apply a π / 2-π-π / 2 pulse sequence to the atom using Raman light to complete the interference process; at this time, the internal state of the atom changes with the interference phase, which is suitable for high-sensitivity measurement.

[0032] B5. Use traditional fluorescence detection or TOF methods to detect the internal state distribution of atoms; in this case, there is no need to use Raman spectroscopy again, because the internal state has directly encoded the phase information.

[0033] B6. Calculate the interference phase based on the number of atoms in the two internal states, and infer the gravity or inertial information.

[0034] The innovation of this invention lies in: First: The optical paths of traditional Raman interferometers and Bragg interferometers are integrated together, and the output of different lights is controlled by a mechanical shutter; Second: In the Raman photo preparation process, three different types of light—blowing light, cooling light, and probe light—can be prepared using only one AOM (Anatomical Oscillator). Third: Bragg light is prepared by frequency shifting two AOMs and then combining them.

[0035] The beneficial effects of this invention are as follows: First: Using fewer optical components, the integrated optical path is more miniaturized, making it portable; Second: By shifting the frequency of two AOMs and then combining them to prepare Bragg light, other frequency components are eliminated from the optical path, thus reducing phase noise; Third: It can greatly improve the utilization rate of the optical path, making the gravity acceleration information more accurate. Attached Figure Description

[0036] Figure 1This is a diagram of the optical path structure of the composite atomic interferometer optical path system of the present invention. Detailed Implementation

[0037] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0038] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0039] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0040] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," 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, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0041] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0042] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0043] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0044] The structure and function of the present invention will be further described below with reference to the accompanying drawings.

[0045] according to Figure 1 The composite atomic interferometer optical path system of the present invention includes a first optical path and a second optical path; The first optical path collimates the first laser F1 and splits it into a first functional base beam, a first beat frequency beam, a second functional base beam, and a locked beam; The second optical path collimates the second laser F2 and splits it into a second beat frequency beam and a third functional base beam; the third functional base beam and the first functional base beam are combined and then split into a Raman light base beam and a fourth functional base beam. The spectral locking branch performs frequency modulation and spectral stabilization based on the locked beam, and provides feedback to lock the frequency of the first laser F1. The beat frequency monitoring branch combines the first beat frequency beam and the second beat frequency beam and inputs them into a high-speed photoelectric probe to realize beat frequency signal monitoring. The functional optical path receives the fourth functional substrate beam and the second functional substrate beam and generates blow-off light, cooling light and probe light; The Raman light preparation branch receives the Raman substrate beam, generates Raman light, and transmits it to the interference light output end; The Bragg beam preparation branch uses a third laser as input to generate Bragg beams, which are then input to the interference beam output terminal. The interference light output terminal can be switched to output Bragg light or Raman light.

[0046] The first laser F1 is generated by an external first external cavity semiconductor laser; the external second external cavity semiconductor laser determines the frequency of the first laser F1 by beating the first external cavity semiconductor laser and generates a second laser F2 that maintains a fixed frequency difference with the first laser F1; the external third external cavity semiconductor laser determines the frequency of the second laser F2 by beating the second external cavity semiconductor laser and generates a third laser F3 that maintains a fixed frequency difference with the second laser F2.

[0047] When combined with an actual atomic interference chamber, the interference light output end is connected to the interference region of the external atomic interferometer chamber; the cooling light is guided to the preparation region of the external atomic interferometer chamber, and the probe light is guided to the probe region of the external atomic interferometer chamber; the blow-off light is guided between the interference region and the probe region.

[0048] The first optical path includes a first laser collimator 110. After being collimated by the first laser collimator 110, the first laser beam passes sequentially through a first Glan Taylor prism 111 and a first half-glass slide 112 before reaching a first polarization beam splitter 113, where it is split into a first reflected beam and a first transmitted beam. The first reflected beam passes through a second half-glass slide 121 and a first mechanical shutter 124 before being output as a first functional base beam. The first transmitted beam passes through a third half-glass slide 114 and enters a second polarization beam splitter 115, where it is split into a first beat frequency beam and a locked base beam. The first beat frequency beam passes through a fourth half-glass slide 122 in a direction perpendicular to the first transmitted beam and enters the beat frequency monitoring branch. The locked base beam exits in the direction of the first transmitted beam, passes through a fifth half-glass slide 116, and enters a third polarization beam splitter 117, where it is split into a locked beam and a second functional base beam. The second functional base beam is emitted in a direction perpendicular to the locking base beam, and passes through the second optical wedge 123 and the second mechanical shutter 137 in sequence to enter the functional optical path; The locked beam is emitted along the direction of the locked substrate beam, passes through the first optical wedge 118, the first composite glass plate 119 and the second laser collimator 120 and enters the fiber electro-optic modulator FEOM; the fiber electro-optic modulator FEOM outputs the locked beam to the spectral locking branch.

[0049] The second optical path includes a third laser collimator 140; The third laser collimator 140 collimates the second laser F2 and emits it to the first reflector 139; After being reflected by the first mirror 139, the second laser F2 passes through the first optical isolator 138 and the sixth half-glass slide 137 in sequence before entering the fourth polarization beam splitter 136, splitting into a second beat frequency beam and a third functional substrate beam. The second beat frequency beam is reflected by the second reflector 125 and passes sequentially through the sixth half glass plate 126 and the third optical wedge 127 before entering the beat frequency monitoring branch. The third functional substrate beam passes through the third mechanical shutter 135 and enters the fifth polarization beam splitter 141, where it is combined with the first functional substrate beam. It exits along the direction of the first functional substrate beam, passes through the seventh half-glass slide 142, and arrives at the sixth polarization beam splitter 143, where it is split into a Raman light substrate beam and a fourth functional substrate beam. The Raman light substrate beam exits along the incident direction to the Raman light preparation branch, while the fourth functional substrate beam exits along the direction perpendicular to the incident direction to the functional light path.

[0050] The beat frequency monitoring branch includes a seventh polarization beam splitter 128; the first beat frequency beam and the second beat frequency beam enter the seventh polarization beam splitter 128 and are combined, and are emitted along the direction of the second beat frequency beam, passing through the eighth half-glass slide 129, the eighth polarization beam splitter 130, the third focusing lens 131 and the fourth optical wedge 132 in sequence before arriving at the high-speed photoelectric probe 133, thereby realizing beat frequency signal monitoring.

[0051] The input of the functional optical path is the fourth functional base beam and the second functional base beam; the fourth functional base beam passes through the first acousto-optic modulator 146 and the eighth half-glass slide 147 in sequence and then enters the ninth polarization beam splitter 148, splitting the beam into a blow-off light base beam and a cooling detection base beam. The blown-off light base beam is emitted in a direction perpendicular to the fourth functional beam. After being reflected by the third reflecting mirror 149, it passes through the fourth mechanical shutter 150, the fifth optical wedge 151, and the second composite glass plate 152 in sequence, and is then output as blown-off light by the fourth laser collimator 153. The cooling probe base beam is emitted along the direction of the fourth functional base beam, passes through the ninth half-glass plate 155 and the sixth optical wedge 156 in sequence, and then enters the ninth polarization beam splitter 157; the second functional base beam passes through the twelfth glass plate 154 and then enters the ninth polarization beam splitter 157, where it is combined with the fourth functional beam and split into a cooling light base beam and a probe light base beam that are perpendicular to each other. The cooling light substrate beam is emitted along the direction of the fourth functional substrate beam, passes sequentially through the fifth mechanical shutter 158, the eleventh and eleventh half glass plate 159, the tenth polarization beam splitter 160, the seventh optical wedge 161 and the third composite glass plate 162, and is collimated by the fifth laser collimator 163 to generate cooling light. The probe light base beam is emitted along the direction of the second functional base beam. After being reflected by the fourth reflector 164, it passes sequentially through the 1 / 2 twelfth glass plate 165, the sixth mechanical shutter 166, the eleventh polarization beam splitter 167, the eighth optical wedge 168, and the fourth composite glass plate 169. Finally, it is collimated by the sixth laser collimator 170 to generate the probe light.

[0052] The spectral locking branch includes a seventh laser collimator 101, which collimates and emits the locking beam. The locking beam passes sequentially through a second light blocker 102, a thirteenth half-glass slide 103, a twelfth polarization beam splitter 104, a first focusing lens 105, a second focusing lens 106, a ninth optical wedge 107, a rubidium chamber, and a fourteenth half-glass slide 108 before reaching a fifth reflecting mirror 109 and being reflected in the opposite direction. The reflected locking beam is reflected by the twelfth polarization beam splitter 104 and then enters a first photodiode 206, where it is collected by an external collector. The external collector locks the frequency of the first laser F1 based on the reflected locking beam.

[0053] The input to the Raman light preparation branch is a Raman light substrate beam. The Raman light substrate beam passes sequentially through the seventh mechanical shutter 144 and the fourteenth half-glass slide 145 and then enters the thirteenth polarization beam splitter 175. After being reflected by the thirteenth polarization beam splitter 175, it exits at an angle perpendicular to the incident direction and passes sequentially through the tenth optical wedge 176, the second electro-optic modulator 177, the fifteenth half-glass slide 178, and the fourth focusing lens 179. After being reflected by the sixth reflecting mirror 180, it passes sequentially in the opposite direction through the fourth focusing lens 179, the fifteenth half-glass slide 178, the second electro-optic modulator 177, the tenth optical wedge 176, the thirteenth polarization beam splitter 175, the fourteenth polarization beam splitter 174, the eleventh optical wedge 173, and the fifth composite glass slide 172. Finally, it is collimated into Raman light by the eighth laser collimator 171 and output to the interference light output end.

[0054] The input to the Bragg beam preparation branch is the third laser F3; after being collimated by the ninth laser collimator 205, the third laser is reflected by the seventh mirror 204 and exits at an angle perpendicular to the incident direction. After passing through the sixteenth half glass plate 203, it enters the fifteenth polarization beam splitter 202 and is split into the fifth functional substrate light and the sixth functional substrate light. The fifth functional substrate beam exits along the direction of the third laser incident on the fifteenth polarization beam splitter 202, and after passing through the sixteenth polarization beam splitter 201 and the third acousto-optic modulator 200, it diffracts into the first zeroth order laser and the first first order electro-optic beam. The first zeroth order laser beam is emitted along the incident direction and passes through the central region of the fifth focusing lens 199 before being absorbed by the first baffle 198. The first-stage laser deviates from the direction of the third laser incident on the fifteenth polarization beam splitter 202 and exits sequentially through the off-axis region of the fifth focusing lens 199, the first quarter glass plate 197, and is then reflected by the eighth reflecting mirror 196. It then passes sequentially through the first quarter glass plate 197, the fifth focusing lens 199, and the third acousto-optic modulator 200 in the opposite direction before entering the sixteenth polarization beam splitter 201 and exiting in a direction perpendicular to the fifth functional substrate beam to the seventeenth polarization beam splitter 185. The sixth functional base beam is emitted in a direction perpendicular to the direction of the third laser incident on the fifteenth polarization beam splitter 202. After passing through the seventeenth half glass plate 195, it is reflected by the ninth mirror 194 and emitted at an angle perpendicular to the incident direction. After passing through the eighteenth polarization beam splitter 193 and the fourth acousto-optic modulator 192, it is diffracted into the second zeroth order laser and the second first order electro-optic beam. The second zeroth order laser is emitted along the incident direction, passes through the central region of the sixth focusing lens 191 and is absorbed by the second baffle 190. The second-stage laser beam deviates from the incident direction and passes sequentially through the off-axis region of the sixth focusing lens 191 and the second quarter glass plate 189. After being reflected by the ninth reflecting mirror 188, it passes sequentially through the second quarter glass plate 189, the sixth focusing lens 191, and the fourth acousto-optic modulator 192 in the opposite direction before entering the eighteenth polarization beam splitter 193. It then exits in a direction perpendicular to the sixth functional base beam to the tenth reflecting mirror 187, exits in a direction perpendicular to the incident direction, passes through the eighteenth half glass plate 186, and is then combined with the first-stage laser beam to form the Bragg base beam. After passing through the eighth mechanical shutter 184 and the fifth acousto-optic modulator 183, the Bragg light substrate light is diffracted into a third zeroth-order laser and a third first-order electro-optic light along the incident direction. The third zeroth-order laser is absorbed by the third baffle 182, and the third first-order electro-optic light passes through the tenth laser collimator 181 and is collimated into Bragg light, and then output to the interference output end.

[0055] The optical path system of the composite atomic interferometer includes two modes of use: one is to use Bragg light to interfere with atoms and use Raman spectroscopy to detect the distribution of momentum states of atoms after interference, thereby improving contrast; the other is to first use Bragg light to apply a large momentum transfer to atoms, and then use Raman light to complete the interference process.

[0056] The specific steps for interfering with atoms using Bragg light and then probing the distribution of momentum states of the atoms after interference using Raman spectroscopy are as follows: A1. Open the first optical path, the second optical path, and the Raman light preparation optical path; the spectral locking branch locks the frequency of the first laser F1 through frequency modulation spectrum.

[0057] A2. The functional optical path generates cooling light, blowing light, and probe light and guides them to the external atomic interference chamber for cooling and initial state preparation of the magneto-optical trap (MOT) of atoms.

[0058] A3. Close the seventh mechanical shutter 144 in the Raman light preparation branch to prevent Raman light output; open the eighth mechanical shutter 184 in the Bragg light preparation branch; after frequency shifting, beam combining and filtering, the third laser F3 is collimated by the tenth laser collimator 181 to generate Bragg light output to the interference light output end.

[0059] A4. A π / 2-π-π / 2 pulse sequence is applied to atoms using Bragg light to achieve atomic interference; the atoms maintain the same internal state throughout the process, avoiding light frequency shift and electromagnetic field noise.

[0060] A5. When an atom enters the detection region, before the atom reaches the first detection window, the seventh mechanical shutter 144 is briefly opened to apply a resonant Raman π pulse and detect one of the interference output states. Before the atom reaches the second detection window, the seventh mechanical shutter 144 is opened again to apply a second resonant Raman π pulse and detect the other interference output state. Through the above two Raman detections, the complete probability distribution of the two output states is obtained.

[0061] A6. Calculate the contrast of the interference fringes based on the detection signal to infer the gravity or phase information.

[0062] The specific steps for applying a large momentum transfer to atoms using Bragg light, followed by using Raman light to complete the interference process, are as follows: B1. Open the first optical path, the second optical path, and the Raman light preparation optical path; the spectral locking branch locks the frequency of the first laser F1 through frequency modulation spectrum.

[0063] B2. The functional optical path generates cooling light, blowing light, and probe light and guides them to the external atomic interference chamber for magneto-optical trap cooling and initial state preparation of atoms.

[0064] B3. Close the seventh mechanical shutter 144; open the eighth mechanical shutter 184; adjust the Bragg light frequency difference through the third acousto-optic modulator 200 and the fourth acousto-optic modulator 192 to apply multiple Bragg diffraction pulses to the atoms, achieving a large momentum transfer. In this process, the atoms gain a large vertical momentum, increasing the interferometer area.

[0065] B4. Close the eighth mechanical shutter 184 and open the seventh mechanical shutter 144; apply a π / 2-π-π / 2 pulse sequence to the atom using Raman light to complete the interference process; at this time, the internal state of the atom changes with the interference phase, which is suitable for high-sensitivity measurement.

[0066] B5. Use traditional fluorescence detection or TOF methods to detect the internal state distribution of atoms; in this case, there is no need to use Raman spectroscopy again, because the internal state has directly encoded the phase information.

[0067] B6. Calculate the interference phase based on the number of atoms in the two internal states, and infer the gravity or inertial information.

Claims

1. An optical path system for a composite atomic interferometer, characterized in that: It includes a first optical path and a second optical path; The first optical path collimates the first laser F1 and splits it into a first functional base beam, a first beat frequency beam, a second functional base beam, and a locked beam; The second optical path collimates the second laser F2 and splits it into a second beat frequency beam and a third functional base beam; the third functional base beam and the first functional base beam are combined and then split into a Raman light base beam and a fourth functional base beam. The spectral locking branch performs frequency modulation and spectral stabilization based on the locked beam, and provides feedback to lock the frequency of the first laser F1. The beat frequency monitoring branch combines the first beat frequency beam and the second beat frequency beam and inputs them into a high-speed photoelectric probe to realize beat frequency signal monitoring. The functional optical path receives the fourth functional substrate beam and the second functional substrate beam and generates blow-off light, cooling light and probe light; The Raman light preparation branch receives the Raman substrate beam, generates Raman light, and transmits it to the interference light output end; The Bragg beam preparation branch uses the third laser F3 as input to generate Bragg beams, which are then input to the interference beam output terminal; the interference beam output terminal can switch between outputting Bragg beams or Raman beams. The first laser F1 and the second laser F2 maintain a fixed frequency difference, and the third laser F3 and the second laser F2 maintain a fixed frequency difference.

2. The optical path system of a composite atomic interferometer according to claim 1, characterized in that: The first optical path includes a first laser collimator (110). After the first laser is collimated by the first laser collimator (110), it passes through the first Glan Taylor prism (111) and the first half-glass slide (112) in sequence and arrives at the first polarization beam splitter (113), where it is split into a first reflected light and a first transmitted light. The first reflected light passes through the second half-glass slide (121) and the first mechanical shutter (124) and is output as a first functional base beam. The first transmitted light passes through the third half-glass slide (114) and enters the second polarization beam splitter (115), where it is split into a first beat frequency beam and a locked base beam. The first beat frequency beam passes through the fourth half-glass slide (122) in a direction perpendicular to the first transmitted light and enters the beat frequency monitoring branch. The locked base beam exits in the direction of the first transmitted light, passes through the fifth half-glass slide (116) and enters the third polarization beam splitter (117), where it is split into a locked beam and a second functional base beam. The second functional base beam is emitted in a direction perpendicular to the locking base beam, and passes through the second optical wedge (123) and the second mechanical shutter (137) in sequence to enter the functional optical path; The locked beam is emitted along the direction of the locked substrate beam, passes through the first optical wedge (118), the first composite glass plate (119), and the second laser collimator (120) before entering the fiber electro-optic modulator FEOM; the fiber electro-optic modulator FEOM outputs the locked beam to the spectral locked branch.

3. The optical path system of a composite atomic interferometer according to claim 1, characterized in that: The second optical path includes a third laser collimator (140); The third laser collimator (140) collimates the second laser F2 and outputs it to the first reflector (139); After being reflected by the first mirror (139), the second laser F2 passes through the first optical isolator (138) and the sixth half-glass slide (137) in sequence before entering the fourth polarization beam splitter (136), where it is split into the second beat frequency beam and the third functional substrate beam. The second beat frequency beam is reflected by the second reflector (125) and passes through the sixth half-glass slide (126) and the third optical wedge (127) in sequence before entering the beat frequency monitoring branch; The third functional substrate beam passes through the third mechanical shutter (135) and enters the fifth polarization beam splitter (141), where it is combined with the first functional substrate beam. It exits along the direction of the first functional substrate beam, passes through the seventh half-glass slide (142), and arrives at the sixth polarization beam splitter (143), where it is split into a Raman light substrate beam and a fourth functional substrate beam. The Raman light substrate beam exits along the incident direction to the Raman light preparation branch, and the fourth functional substrate beam exits along the direction perpendicular to the incident direction to the functional light path.

4. The optical path system of a composite atomic interferometer according to claim 1, characterized in that: The beat frequency monitoring branch includes a seventh polarization beam splitter (128); the first beat frequency beam and the second beat frequency beam enter the seventh polarization beam splitter (128) and are combined, and are emitted along the direction of the second beat frequency beam, passing through the eighth half glass plate (129), the eighth polarization beam splitter (130), the third focusing lens (131) and the fourth optical wedge (132) in sequence before arriving at the high-speed photoelectric probe (133) to realize beat frequency signal monitoring.

5. The optical path system of a composite atomic interferometer according to claim 1, characterized in that: The input of the functional optical path is the fourth functional base beam and the second functional base beam; the fourth functional base beam passes through the first acousto-optic modulator (146) and the eighth half-glass slide (147) in sequence and then enters the ninth polarization beam splitter (148), splitting into a blow-off light base beam and a cooling detection base beam. The blown-off light base beam is emitted in a direction perpendicular to the fourth functional beam. After being reflected by the third mirror (149), it passes through the fourth mechanical shutter (150), the fifth optical wedge (151), and the second composite glass plate (152) in sequence, and is output as blown-off light through the fourth laser collimator (153). The cooling probe substrate beam is emitted along the direction of the fourth functional substrate beam, passes through the ninth half-glass plate (155) and the sixth optical wedge (156) in sequence, and then enters the ninth polarization beam splitter (157); the second functional substrate beam passes through the twelfth glass plate (154) and then enters the ninth polarization beam splitter (157), where it is combined with the fourth functional beam and split into a cooling light substrate beam and a probe light substrate beam that are perpendicular to each other. The cooling light substrate beam is emitted along the direction of the fourth functional substrate beam, passes sequentially through the fifth mechanical shutter (158), the eleventh and twelfth glass plate (159), the tenth polarization beam splitter (160), the seventh optical wedge (161) and the third composite glass plate (162), and is then collimated by the fifth laser collimator (163) to generate cooling light; The probe light base beam is emitted along the direction of the second functional base beam. After being reflected by the fourth mirror (164), it passes sequentially through the 1 / 2 twelfth glass plate (165), the sixth mechanical shutter (166), the eleventh polarization beam splitter (167), the eighth optical wedge (168), and the fourth composite glass plate (169). Finally, it is collimated by the sixth laser collimator (170) to generate the probe light.

6. The optical path system of a composite atomic interferometer according to claim 1, characterized in that: The spectral locking branch includes a seventh laser collimator (101), which collimates and emits the locking beam. The locking beam passes sequentially through the second light blocker (102), the thirteenth half-glass slide (103), the twelfth polarization beam splitter (104), the first focusing lens (105), the second focusing lens (106), the ninth optical wedge (1070), the rubidium chamber, and the fourteenth half-glass slide (108) before reaching the fifth reflecting mirror (109) and being reflected in the opposite direction. The reflected locking beam is reflected by the twelfth polarization beam splitter (104) and then enters the first photodiode (206) where the optical signal is collected by an external collector. The external collector locks the frequency of the first laser F1 based on the reflected locking beam.

7. The optical path system of a composite atomic interferometer according to claim 1, characterized in that: The input to the Raman light preparation branch is a Raman light substrate beam; the Raman light substrate beam passes sequentially through the seventh mechanical shutter (144) and the fourteenth half-glass slide (145) before entering the thirteenth polarization beam splitter (175). After being reflected by the thirteenth polarization beam splitter (175), it exits at an angle perpendicular to the incident direction and sequentially passes through the tenth optical wedge (176), the second electro-optic modulator (177), the fifteenth half-glass slide (178), and the fourth focusing lens (179). After being reflected by the sixth reflecting mirror (180), the light passes sequentially in the opposite direction through the fourth focusing lens (179), the fifteenth half-glass slide (178), the second electro-optic modulator (177), the tenth optical wedge (176), the thirteenth polarization beam splitter (175), the fourteenth polarization beam splitter (174), the eleventh optical wedge (173), and the fifth composite glass slide (172). It is then collimated into Raman light by the eighth laser collimator (171) and output to the interference light output end.

8. The optical path system of a composite atomic interferometer according to claim 1, characterized in that: The input to the Bragg beam preparation branch is the third laser F3; the third laser is collimated by the ninth laser collimator (205), reflected by the seventh mirror (204), and emitted at an angle perpendicular to the incident direction. After passing through the sixteenth half glass plate (203), it enters the fifteenth polarization beam splitter (202) and is split into the fifth functional substrate light and the sixth functional substrate light. The fifth functional substrate beam exits along the direction of the third laser incident on the fifteenth polarization beam splitter (202), and after passing through the sixteenth polarization beam splitter (201) and the third acousto-optic modulator (200), it diffracts into the first zeroth order laser and the first first order electro-optic beam. The first zeroth order laser beam is emitted along the incident direction and passes through the central region of the fifth focusing lens (199), where it is absorbed by the first baffle (198). The first-stage laser beam deviates from the direction of the third laser beam incident on the fifteenth polarization beam splitter (202) and passes through the off-axis region of the fifth focusing lens (199) and the first quarter glass plate (197) in sequence. After being reflected by the eighth mirror (196), it passes through the first quarter glass plate (197), the fifth focusing lens (199), and the third acousto-optic modulator (200) in the opposite direction in sequence before entering the sixteenth polarization beam splitter (201). It then exits in a direction perpendicular to the beam of the fifth functional substrate to the seventeenth polarization beam splitter (185). The sixth functional base beam is emitted in a direction perpendicular to the direction of the third laser incident on the fifteenth polarization beam splitter (202), passes through the seventeenth half glass plate (195), is reflected by the ninth mirror (194), and is emitted at an angle perpendicular to the incident direction. After passing through the eighteenth polarization beam splitter (193) and the fourth acousto-optic modulator (192), it diffracts into the second zeroth order laser and the second first order electro-optic beam. The second zeroth order laser is emitted along the incident direction, passes through the central region of the sixth focusing lens (191), and is absorbed by the second baffle (190); The second-stage laser beam deviates from the incident direction and passes through the off-axis region of the sixth focusing lens (191) and the second quarter glass plate (189) in sequence. After being reflected by the ninth mirror (188), it passes through the second quarter glass plate (189), the sixth focusing lens (191), and the fourth acousto-optic modulator (192) in the opposite direction before entering the eighteenth polarization beam splitter (193). It exits to the tenth mirror (187) in a direction perpendicular to the sixth functional base beam, exits in a direction perpendicular to the incident direction, passes through the eighteenth half glass plate (186), and is then combined with the first-stage laser beam to form the Bragg base beam. After passing through the eighth mechanical shutter (184) and the fifth acousto-optic modulator (183), the Bragg light substrate light is diffracted into the third zeroth order laser and the third first order electron beam along the incident direction. The third zeroth order laser is absorbed by the third baffle (182), and the third first order electron beam passes through the tenth laser collimator (181) and is collimated into Bragg light, and is output to the interference output end.

9. The optical path system of a composite atomic interferometer according to claim 1, characterized in that: The first laser F1 is generated by an external first external cavity semiconductor laser; the external second external cavity semiconductor laser determines the frequency of the first laser F1 by beating the first external cavity semiconductor laser and generates a second laser F2 that maintains a fixed frequency difference with the first laser F1; the external third external cavity semiconductor laser determines the frequency of the second laser F2 by beating the second external cavity semiconductor laser and generates a third laser F3 that maintains a fixed frequency difference with the second laser F2.

Images