Optical super-surface based circulating light path atomic cell structure

Abstract

The application discloses a kind of circulating light path atomic cell structures based on optical super surface, including atomic cell, atomic cell includes cell wall and chamber, chamber is vacuum environment, and chamber is filled with alkali metal atom vapor;The first optical super surface structure and the second optical super surface structure with the same structure are symmetrically arranged on the two sides of the chamber;Atomic cell is provided with probe light input interface and coupled light input interface respectively on two sides;The inside of cell wall is provided with probe light path;Probe light input interface is coaxially arranged with chamber;The application provides an integrated atomic cell structure, reduces the number of optical devices of electric field measurement system, reduces the influence of environmental factors on measurement, improves the portability and practicality of the measurement based on Rydberg atom electric field.The application does not depend on optical platform and does not contain metal element, and the measured electric field will not be distorted, which can be directly used as an electric field measurement probe in the measured electric field.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of atomic gas cell, in particular to a circulating light path atomic gas cell structure based on optical super surface. BACKGROUND

[0002] With the maturity of laser technology and the development of precise manipulation of atomic quantum states by laser, the AC Stark shift generated by the electric field is currently detected by using the electromagnetically induced transparency (EIT) based on Rydberg atoms, so as to realize the precise measurement of the electric field. The main components in the experiment of electric field measurement based on Rydberg atoms are: a vacuum alkali metal atomic gas cell and a laser. The vacuum alkali metal atomic gas cell is generally a transparent quartz glass chamber, and alkali metal atoms and inert buffer gas are filled in the chamber. The laser outputs two lasers with different wavelengths, which are called probe light and coupling light respectively. The two lasers are transmitted in an optical fiber, collimated by a gradient refractive index lens, and then enter the atomic gas cell for opposite transmission. The probe light and the coupling light excite the alkali atoms to the Rydberg state, so that the two excitation channels produce destructive interference. The EIT spectrum of the Rydberg atom is realized by the two-photon excitation mode, and the required strong coupling light power is usually in the order of tens of milliwatts. If the coupling light power cannot meet the requirements, the obtained EIT signal intensity will be low, the signal linewidth will be increased, and the measurement precision of the electric field will be reduced. In order to obtain better EIT signal effect, a circulating light path of the coupling light can be built to enhance the utilization rate of the coupling light, increase the coupling light power in the alkali atomic gas cell, and realize the enhancement of the EIT signal.

[0003] The required strong coupling light power is usually in the order of tens of milliwatts. If the coupling light power cannot meet the requirements, the obtained EIT signal intensity will be low, the signal linewidth will be increased, and the measurement precision of the electric field will be reduced. In order to obtain better EIT signal effect, a circulating light path of the coupling light can be built to enhance the utilization rate of the coupling light, increase the coupling light power in the alkali atomic gas cell, and realize the enhancement of the EIT signal.

[0004] At present, the coupling light circulating light path scheme separates the coupling light by using a dichroic mirror, and combines the unused outgoing coupling light with the incident coupling light by using a polarization beam splitter through a full reflection mirror. The optical instrument requires high precision, and is also highly dependent on the optical platform. In the precise measurement of the electric field based on Rydberg atoms, a large number of optical elements are required, and each element is separate. The optical path is complex, the optical path precision is high, the space occupation is large, and the adjustment is complex, which greatly limits the use environment. If the coupling light circulating light path is additionally built on this basis, the adverse effects will be further expanded. At the same time, some metal devices on the optical platform will also have a certain impact on the measurement of the measured electric field. SUMMARY

[0005] In view of the above shortcomings of the prior art, the present application provides a circulating light path atomic gas cell structure based on optical super surface, which has small space occupation and high stability, and will not cause distortion of the measured electric field.

[0006] To achieve the above-mentioned application purposes, the technical scheme adopted by the present application is:

[0007] Provided is a circulating light path atomic cell structure based on an optical super surface, comprising an atomic cell, the atomic cell comprising a cell wall and a chamber, the chamber being a vacuum environment, and the chamber being filled with alkali metal atom vapor; a first optical super surface structure and a second optical super surface structure with the same structure are symmetrically arranged on two sides of the chamber;

[0008] A detection light input interface and a coupling light input interface are arranged on the two sides of the atomic cell respectively; the inside of the cell wall is provided with a detection light path;

[0009] The detection light input interface is coaxially arranged with the chamber; the detection light path comprises: the detection light enters the cell wall through the detection light input interface, and is emitted out of the atomic cell after sequentially passing through the first optical super surface structure, the alkali metal atom vapor and the second optical super surface structure; and the detection light is vertically incident on the first optical super surface structure and the second optical super surface structure;

[0010] The coupling circulating light path structure is embedded in the cell wall; the coupling light enters the coupling circulating light path through the coupling light input interface, and the coupling light input interface is arranged to be inclined to the detection light, and the coupling light is obliquely incident on the second optical super surface structure, and the coupling light is refracted under the action of the super material unit of the second optical super surface structure, and the angle between the incident angle of the coupling light and the detection light is the same as the refraction angle of the coupling light; the coupling light becomes residual coupling light after being absorbed by the alkali metal atom vapor, and the residual coupling light is also refracted when being emitted out of the first optical super surface structure, and the residual coupling light is combined with the coupling light newly entering the cell wall under the action of the coupling circulating light path structure, to form a coupling light circulating light path.

[0011] Further, the detection light input interface comprises a detection light fiber interface and a first gradient lens; the coupling light input interface comprises a coupling light fiber interface and a second gradient lens; and the first gradient lens and the second gradient lens are embedded in the cell wall.

[0012] Further, the coupling circulating light path structure comprises a polarization beam splitter, a half-wave plate and a plurality of dielectric film mirrors; the polarization beam splitter and the half-wave plate are embedded in the cell wall;

[0013] The coupling light enters the cell wall through the coupling light input interface, and sequentially passes through the polarization beam splitter, the second optical super surface structure, the alkali metal atom vapor and the first optical super surface structure; the coupling light becomes residual coupling light after being absorbed by the alkali metal atom vapor, and the residual coupling light is vertically incident on the half-wave plate under the action of the plurality of film mirrors when being emitted out of the first optical super surface structure; the residual coupling light is incident on the polarization beam splitter perpendicularly to the incident angle of the coupling light after passing through the half-wave plate; and the polarization beam splitter is used to combine the residual coupling light with the coupling light to enter the coupling circulating light path.

[0014] Further, the medium film mirror has two, including a first mirror and a second mirror; the remaining coupling light is sequentially reflected by the first mirror and the second mirror and then is emitted to the half-wave plate; the first mirror is located at one side of the atomic cell where the probe light input interface is located; and the second mirror is located at one side of the atomic cell where the probe light input interface or the coupling light input interface is located.

[0015] Further, the side wall where the second mirror is located is obliquely arranged between the side wall where the probe light input interface is located, and the oblique angle is ; wherein, is the incident angle of the remaining coupling light into the second mirror; is the incident angle of the coupling light into the second optical super surface structure; and the second mirror and the second optical super surface structure are located on the same perpendicular line of the probe light;

[0016] The distance between the coupling light input interface and the probe light is ; wherein, f is the length of the second optical super surface structure along the direction of the probe light from the outer wall of the atomic cell;

[0017] The distance between the first mirror and the probe light is ; wherein, a is the length of the probe light fiber interface from the first optical super surface structure;

[0018] The length of the side wall where the probe light input interface is located from the side wall where the second mirror is located is ;

[0019] The length of the side wall where the second mirror is located in the atomic cell is ; wherein, d is the length of the chamber in the direction of the probe light.

[0020] Further, the incident angle of the remaining coupling light into the second mirror is .

[0021] Further, the medium film mirror includes a substrate material, and a plurality of reflective film groups are arranged on the substrate material; each reflective film group includes a SiO2 film and a Nb2O5 film; one side of the SiO2 film is connected with the Nb2O5 film, and the other side of the SiO2 film is connected with the substrate material or the Nb2O5 film of the adjacent reflective film group.

[0022] Further, the number of layers of the reflective film group p is in the range of [5, 9].

[0023] Further, the thickness of the SiO2 film is 88.59 nm, and the thickness of the Nb2O5 film is 54.94 nm; and the optical thickness of the SiO2 film and the Nb2O5 film is . For coupling the wavelength of light.

[0024] The beneficial effects of the present application are:

[0025] 1. The present application provides an integrated atomic cell structure, which reduces the number of optical devices of the electric field measurement system, reduces the influence of environmental factors on the measurement, and improves the portability and practicality of the electric field measurement based on Rydberg atoms.

[0026] 2. The atomic cell structure designed in the present application does not depend on an optical platform and does not contain metal elements, and will not distort the electric field to be measured, and can be directly placed into the electric field to be measured as an electric field measurement probe.

[0027] 3. The present application integrates and optimizes the circulating light path, uses the cell material as the propagation medium of the coupling light circulating light path, which not only can increase the EIT signal and reduce the power requirement of the laser, but also avoids adding other discrete optical elements. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 It is an internal structure schematic diagram of the embodiment 1 of the present application.

[0029] Figure 2 It is an internal structure schematic diagram of the embodiment 2 of the present application.

[0030] Figure 3 It is a structure schematic diagram of the dielectric film mirror.

[0031] 1, atomic cell, 101, cell wall, 102, chamber; 2, first optical super surface structure; 3, second optical super surface structure; 4, probe light input interface; 401, probe light fiber interface; 402, first gradient lens; 5, coupling light input interface; 501, coupling light fiber interface; 502, second gradient lens; 6, polarization beam splitter; 7, half-wave plate; 8, first mirror; 9, second mirror; 10, substrate material; 11, reflective film group; 111, SiO2 film; 112, Nb2O5 film; 12, probe light; 13, coupling light; 14, residual coupling light; 15, photodetector. DETAILED DESCRIPTION

[0032] The specific embodiments of the present application are described below to facilitate those skilled in the art to understand the present application, but it should be clear that the present application is not limited to the scope of the specific embodiments, and for those skilled in the art, it is obvious that various changes are within the spirit and scope of the present application defined and determined by the appended claims, and all the inventions utilizing the concept of the present application are within the scope of protection.

[0033] Embodiment 1

[0034] AsFigure 1 As shown in the figure, a circulating light path atomic cell structure based on an optical super surface includes an atomic cell 1, the atomic cell 1 includes a cell wall 101 and a chamber 102, the chamber 102 is a vacuum environment, and the chamber 102 is filled with alkali metal atom vapor; The first optical super surface structure 2 and the second optical super surface structure 3 with the same structure are symmetrically arranged on both sides of the chamber 102;

[0035] The probe light 12 and the coupling light 13 usually adopt lasers with different wavelengths, and the embodiment adopts 852nm wavelength probe light 12 and 509nm wavelength coupling light 13;

[0036] The optical super surface structure is prior art, and the optical super surface structure is a new structure based on the generalized Snell's law, composed of super material structure units, and the electromagnetic optical beam is controlled by controlling the wavefront phase, amplitude and polarization.

[0037] The generalized Snell's law is:

[0038] wherein, n i is the incident medium refractive index, n t is the exit medium refractive index, dφ / dx is the abrupt phase introduced by the super surface, k is a constant, θ i is the incident angle, θ t is the refraction angle, λ is the wavelength.

[0039] When the 852nm wavelength probe light 12 is vertically incident on the optical super surface structure, that is, θ i =0, if is satisfied, then other arbitrary wavelengths, that is, the 509nm wavelength coupling light 13 in the embodiment will be refracted when passing through the optical super surface. Therefore, the super surface will not have a refraction angle for the vertically incident probe light 12, but will have an angle deflection phenomenon for the vertically incident coupling light 13. Thus, it can be used in the present application to realize the coupling circulating light path.

[0040] The atomic cell 1 is respectively provided with a probe light input interface 4 and a coupling light input interface 5 on both sides; The inside of the cell wall 101 is provided with a probe light path;

[0041] ​The probe light input interface 4 is coaxially arranged with the chamber 102; the probe light path comprises: the probe light 12 is emitted into the chamber wall 101 through the probe light input interface 4, sequentially passes through the first optical super surface structure 2, the alkali metal atom vapor and the second optical super surface structure 3, and is emitted out of the atomic chamber 1 to be received by the photodetector 15; and the probe light 12 is vertically emitted to the first optical super surface structure 2 and the second optical super surface structure 3;

[0042] The chamber wall 101 is embedded with a coupling circulating light path structure; the coupling light 13 enters the coupling circulating light path through the coupling light input interface 5, and the coupling light input interface 5 is arranged to be inclined to the probe light 12, the coupling light 13 is obliquely emitted to the second optical super surface structure 3, and the coupling light 13 is refracted under the action of the super material unit of the second optical super surface structure 3, and the angle between the incident angle of the coupling light 13 and the probe light 12 is the same as the refraction angle of the coupling light 13; the coupling light 13 becomes the residual coupling light 14 after being absorbed by the alkali metal atom vapor, the residual coupling light 14 is emitted out of the first optical super surface structure 2 and also refracted, and the residual coupling light 14 is combined with the coupling light 13 newly entering the chamber wall 101 under the action of the coupling circulating light path structure, to form the coupling light 13 circulating light path.

[0043] The probe light input interface 4 comprises a probe light fiber interface 401 and a first gradient lens 402; the coupling light input interface 5 comprises a coupling light fiber interface 501 and a second gradient lens 502; and the first gradient lens 402 and the second gradient lens 502 are embedded in the chamber wall 101.

[0044] The coupling circulating light path structure comprises a polarization beam splitter 6, a half-wave plate 7 and a plurality of dielectric film mirrors; the polarization beam splitter 6 and the half-wave plate 7 are embedded in the chamber wall 101;

[0045] The coupling light 13 is emitted into the chamber wall 101 through the coupling light input interface 5, sequentially passes through the polarization beam splitter 6, the second optical super surface structure 3, the alkali metal atom vapor and the first optical super surface structure 2, becomes the residual coupling light 14 after being absorbed by the alkali metal atom vapor, is emitted out of the first optical super surface structure 2, and is vertically emitted to the half-wave plate 7 under the action of the plurality of film mirrors; the residual coupling light 14 is emitted to the polarization beam splitter 6 perpendicularly to the incident angle of the coupling light 13 after passing through the half-wave plate 7; the polarization beam splitter 6 is used for combining the residual coupling light 14 and the coupling light 13 to enter the coupling circulating light path.

[0046] The medium film mirror has two, including a first mirror 8 and a second mirror 9; the remaining coupling light 14 is sequentially reflected by the first mirror 8 and the second mirror 9 and then is emitted to the half-wave plate 7; the first mirror 8 is located on the side of the atomic chamber 1 where the probe light input interface 4 is located; the second mirror 9 is located on the side of the atomic chamber 1 where the probe light input interface 4 or the coupling light input interface 5 is located. In the embodiment, as shown in the figure, Figure 1 the probe light input interface 4 is located on the left side of the atomic chamber 1, and the coupling light input interface 5 is located on the right side of the atomic chamber 1; the first mirror 8 is also located on the left side of the atomic chamber 1; the second mirror 9 is located on the lower side of the atomic chamber 1, and in other embodiments of the application, the second mirror 9 can also be located on the upper side, the front side and the rear side of the atomic chamber 1.

[0047] As shown in the figure, Figure 3 the medium film mirror includes a substrate material 10, and a plurality of layers of reflective film groups 11 are covered on the substrate material 10; the reflective film group includes a SiO2 film 111 and a Nb2O5 film 112; one side of the SiO2 film 111 is connected with the Nb2O5 film 112, and the other side of the SiO2 film 111 is connected with the substrate material 10 or the Nb2O5 film 112 of the adjacent reflective film group 11. In the embodiment, the number of layers p of the reflective film group 11 is 5, and in other embodiments of the application, p can also be 6, 7, 8 or 9.

[0048] The thickness of the SiO2 film 111 is 88.59 nm, and the thickness of the Nb2O5 film 112 is 54.94 nm; and the optical thicknesses of the SiO2 film 111 and the Nb2O5 film 112 are both ; the wavelength of the coupling light 13.

[0049] Embodiment 2

[0050] The difference between the embodiment and the embodiment 1 is that the side wall where the second mirror 9 is located is obliquely arranged with the side wall where the probe light input interface 4 is located, that is, in the embodiment, the lower side wall of the atomic chamber 1 is obliquely arranged with the left side wall of the atomic chamber 1, and the oblique angle is ; wherein, is the incident angle of the remaining coupling light 14 entering the second mirror 9; is the incident angle of the coupling light 13 entering the second optical super surface structure 3; is set according to the adopted optical super surface structure; and the second mirror 9 and the second optical super surface structure 3 are located on the same perpendicular line of the probe light 12;

[0051] The distance between the coupling light input interface 5 and the probe light 12 is ; wherein, fL2 is the length of the second optical metasurface structure 3 along the direction of the probe light 12 from the outer wall of the atomic cell 1;

[0052] L1 is the distance between the first mirror 8 and the probe light 12 ; wherein, a L4 is the length of the probe light fiber interface 401 from the first optical metasurface structure 2;

[0053] L3 is the length of the probe light input interface 4 along the side wall from the side wall where the second mirror 9 is located ;

[0054] L5 is the length of the side wall of the atomic cell 1 where the second mirror 9 is located ; wherein, d L6 is the length of the chamber 102 in the direction of the probe light 12.

[0055] L7 is the incident angle of the remaining coupled light 14 into the second mirror 9 .

Claims

1. A circulating optical path atomic gas cell structure based on an optical metasurface, comprising an atomic gas cell (1), the atomic gas cell (1) comprising a cell wall (101) and a cavity (102), wherein the cavity (102) is a vacuum environment and is filled with alkali metal atomic vapor; characterized in that, The chamber (102) is symmetrically provided with a first optical metasurface structure (2) and a second optical metasurface structure (3) having the same structure on both sides. The atomic gas chamber (1) is provided with a probe light input interface (4) and a coupling light input interface (5) on both sides respectively; a probe light path is provided inside the gas chamber wall (101); The probe light input interface (4) is coaxially arranged with the chamber (102); the probe light path includes: the probe light (12) enters the gas chamber wall (101) through the probe light input interface (4), passes through the first optical metasurface structure (2), the alkali metal atomic vapor and the second optical metasurface structure (3) in sequence and then exits the atomic gas chamber (1); and the probe light (12) is perpendicular to the first optical metasurface structure (2) and the second optical metasurface structure (3); The gas chamber wall (101) is embedded with a coupling loop optical path structure; the coupling light (13) enters the coupling loop optical path through the coupling light input interface (5), and the coupling light input interface (5) makes the incident angle of the coupling light (13) tilted with the probe light (12). The coupling light (13) is tilted towards the second optical metasurface structure (3), and under the action of the metamaterial unit of the second optical metasurface structure (3), it is refracted, and the angle between the incident angle of the coupling light (13) and the probe light (12) is the same as the refraction angle of the coupling light (13); after the coupling light (13) is absorbed by the alkali metal atom vapor, it becomes the residual coupling light (14). The residual coupling light (14) is emitted from the first optical metasurface structure (2) and is also refracted. Under the action of the coupling loop optical path structure, the residual coupling light (14) is combined with the newly entered coupling light (13) in the gas chamber wall (101) to form the coupling light (13) loop optical path; The coupled circular optical path structure includes a polarizing beam splitter (6), a half-wave plate (7), and several dielectric film reflectors; the polarizing beam splitter (6) and the half-wave plate (7) are both embedded in the gas chamber wall (101); The coupled light (13) enters the gas chamber wall (101) through the coupled light input interface (5), and passes through the polarizing beam splitter (6), the second optical metasurface structure (3), the alkali metal atom vapor and the first optical metasurface structure (2) in sequence. After being absorbed by the alkali metal atom vapor, the coupled light (13) becomes the residual coupled light (14). The residual coupled light (14) is emitted from the first optical metasurface structure (2) and is perpendicularly incident on the half-wave plate (7) under the action of several film mirrors. After passing through the half-wave plate (7), the residual coupled light (14) is perpendicular to the incident angle of the coupled light (13) and is incident on the polarizing beam splitter (6). The polarizing beam splitter (6) is used to combine the residual coupled light (14) and the coupled light (13) into the coupled loop optical path. There are two dielectric film reflectors, including a first reflector (8) and a second reflector (9); the remaining coupled light (14) passes through the first reflector (8) and the second reflector (9) in sequence and then shines on the half-wave plate (7); the first reflector (8) is located on the side of the atomic gas cell (1) where the probe light input interface (4) is located; the second reflector (9) is located on the side of the atomic gas cell (1) where the probe light input interface (4) or the coupled light input interface (5) is not located; The sidewall where the second reflector (9) is located is inclined relative to the sidewall where the probe light input interface (4) is located, and the inclination angle is . ;in, The incident angle of the remaining coupled light (14) into the second reflecting mirror (9); The incident angle of the coupling light (13) into the second optical metasurface structure (3); and the second reflector (9) and the second optical metasurface structure (3) are located on the same probe light (12) perpendicular line; The distance between the coupled optical input interface (5) and the probe light (12) is... ;in, f The distance from the outer wall of the atomic gas chamber (1) along the direction of the probe light (12) to the second optical metasurface structure (3); The distance between the first reflector (8) and the probe light (12) ;in, a To detect the length of the optical fiber interface (401) from the first optical metasurface structure (2); The distance from the probe light input interface (4) to the sidewall where the second reflector (9) is located along the direction of its location is: ; The length of the side wall of the atomic gas chamber (1) where the second reflecting mirror (9) is located ;in, d The length of the chamber (102) in the direction of the probe light (12) is given.

2. The cyclic optical path atomic gas cell structure based on optical metasurfaces according to claim 1, characterized in that, The probe light input interface (4) includes a probe light fiber optic interface (401) and a first cascade lens (402); the coupling light input interface (5) includes a coupling light fiber optic interface (501) and a second cascade lens (502); and the first cascade lens (402) and the second cascade lens (502) are both embedded in the gas chamber wall (101).

3. The cyclic optical path atomic gas cell structure based on optical metasurfaces according to claim 1, characterized in that, The incident angle of the remaining coupled light (14) into the second reflecting mirror (9) .

4. The cyclic optical path atomic gas cell structure based on optical metasurfaces according to claim 1, characterized in that, The dielectric film reflector includes a substrate material (10) on which a plurality of reflective film groups (11) are coated. The reflective film groups include a SiO2 thin film (111) and a Nb2O5 thin film (112). One side of the SiO2 thin film (111) is connected to the Nb2O5 thin film (112), and the other side of the SiO2 thin film (111) is connected to the substrate material (10) or the Nb2O5 thin film (112) of the adjacent reflective film group (11).

5. The cyclic optical path atomic gas cell structure based on optical metasurface according to claim 4, characterized in that, The number of layers of the reflective film group (11) is p∈[5,9].

6. The cyclic optical path atomic gas cell structure based on optical metasurface according to claim 4, characterized in that, The SiO2 thin film (111) has a thickness of 88.59 nm, and the Nb2O5 thin film (112) has a thickness of 54.94 nm; and the optical thicknesses of both the SiO2 thin film (111) and the Nb2O5 thin film (112) are... ; The wavelength of the coupled light (13) is given.

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