A super-surface lens-loaded atomic gas chamber probe

Abstract

The present invention belongs to the field of quantum microwave measurement, and specifically relates to an atomic gas chamber probe loaded with a metasurface lens, comprising an atomic gas chamber probe and a metasurface lens for microwave focusing, wherein the atomic gas chamber of the atomic gas chamber probe is placed near the focus of the metasurface lens, and the shape of the focus of the metasurface lens is designed according to the effective action area of ​​the atomic gas chamber probe. Compared with the existing atomic receiving antenna, the beneficial effect of the present invention is to use the metasurface lens to perform microwave focusing, place the atomic gas chamber of the existing atomic gas chamber probe at its focus, and use the large aperture brought by the metasurface lens to focus the plane microwaves in a specific direction to the atomic gas chamber, thereby avoiding clutter interference in directions of no interest, and enhancing its responsive microwave power density, thereby increasing the detection sensitivity of the atomic receiving antenna, and supporting the application of quantum microwave measurement systems in electronic information fields such as radar, communication, electronic countermeasures, and navigation.

Description

Technical Field

[0001] The invention belongs to the field of quantum microwave measurement, and in particular relates to an atomic gas chamber probe loaded with a supersurface lens. Background Art

[0002] Atomic gas chamber probe refers to a receiving antenna made by using the quantum coherence effect of Rydberg atoms and microwaves. The physical size of this atomic gas chamber probe is weakly related to the wavelength of the electromagnetic wave to be measured. It mainly responds to the electric field component of the electromagnetic wave, has extremely high sensitivity, and has the advantages of no disturbance, traceability, and self-calibration. In recent years, this type of atomic receiving antenna technology has developed rapidly and has received widespread attention. It has broad application prospects in the fields of microwave electric field strength measurement and radio frequency receivers.

[0003] A metasurface is an artificial planar electromagnetic structure, usually composed of a series of subwavelength metal units in a periodic or quasi-periodic manner. The phase of the electromagnetic wave can be adjusted by changing the structural dimensions of the metal units. By arranging the metasurface metal units according to the phase distribution of a focusing lens, a metasurface lens can be formed.

[0004] The existing atomic gas chamber probe includes a first optical fiber port 1, a second optical fiber port 2, a third optical fiber port 3, an atomic gas chamber 4, and a dichroic mirror 5 (see Chinese invention patent application: Lin Yi, Mao Ruiqi, Liu Yi, etc. A high-efficiency optical fiber coupled atomic gas chamber probe and its manufacturing method: CN 114325130, publication date: 2022-04-12). Under normal circumstances, this type of atomic receiving antenna is used alone in free space and has a performance close to omnidirectional reception. It cannot effectively suppress the direction of the interference signal wave, nor can it effectively gather the energy in the direction of the signal wave. Therefore, it is necessary to develop an atomic receiving antenna that uses a metasurface lens to focus the beam, increase the microwave receiving aperture, and effectively improve the gain and perform spatial filtering in specific situations. Summary of the invention

[0005] The present invention provides an atomic gas chamber probe loaded with a supersurface lens, which can effectively improve the gain of an atomic receiving antenna and perform spatial domain filtering.

[0006] The technical solution adopted by the present invention is: an atomic gas chamber probe loaded with a metasurface lens, comprising an atomic gas chamber probe (see Chinese invention patent application for details: Lin Yi, Mao Ruiqi, Liu Yi, etc. A high-efficiency fiber-coupled atomic gas chamber probe and its manufacturing method, application number: 202111634554.3, publication date: 2022-04-12) and a metasurface lens for microwave bunching, the atomic gas chamber of the atomic gas chamber probe is placed near the focus of the metasurface lens, and the shape of the focus of the metasurface lens is designed according to the effective action area of ​​the atomic gas chamber probe.

[0007] Furthermore, the metasurface lens includes a dielectric substrate and a plurality of lens units, wherein the shape of the metasurface lens is a cross, lens units are provided on both the front and back sides of the dielectric substrate, the phase shift range generated by the lens units covers 0 to 2π, and the lens units on the front and back sides of the dielectric substrate are arranged in a periodic array according to a grid distribution, and the focal shape formed can fit the effective working area of ​​the atomic antenna.

[0008] Compared with the existing atomic receiving antenna, the beneficial effect of the present invention is to use the metasurface lens for microwave focusing, place the atomic gas chamber of the existing atomic gas chamber probe at its focus, and use the large aperture brought by the metasurface lens to focus the plane microwaves in a specific direction to the atomic gas chamber, avoiding clutter interference in directions of no interest, and enhancing its responsive microwave power density, thereby increasing the detection sensitivity of the atomic receiving antenna and supporting the application of quantum microwave measurement systems in electronic information fields such as radar, communication, electronic countermeasures, and navigation. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic diagram of the overall structure of an atomic gas chamber probe loaded with a super-surface lens provided by the present invention;

[0010] Figure 2 It is a schematic diagram of the structure of a metasurface lens unit provided by the present invention;

[0011] Figure 3 It is a schematic diagram of the overall structure of a metasurface lens provided by the present invention;

[0012] Figure 4 is a phase connection coverage curve achieved by the lens unit structure of the present invention;

[0013] Figure 5 It is a receiving pattern of a specific implementation mode of the present invention. DETAILED DESCRIPTION

[0014] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0015] The present invention provides a super-surface lens-loaded atomic gas chamber probe, such as Figure 1As shown, it includes: an existing atomic gas chamber probe and a metasurface lens 6; the atomic gas chamber probe includes a first port 1, a second port 2, a third port 3, an atomic gas chamber 4, and a dichroic mirror 5, wherein the first port 1 is a detection light input port, the second port 2 is a coupling light input port, and the third port 3 is a detection light output port. The first port 1 and the second port 2 are respectively used to provide a detection laser and a coupling laser for counter-transmission into the atomic gas chamber 4, and the two beams of light have the same polarization direction. The dichroic mirror 5 deflects the coupling light input from the second port 2 by 90° and then enters the atomic gas chamber 4. The detection light input from the first port 1 passes through the atomic gas chamber 4, directly passes through the dichroic mirror 5, and then enters the third port 3 and enters the photodetector. The area where the detection light and the coupling light in the atomic gas chamber probe pass together is the effective working area.

[0016] like Figure 2 As shown, one unit of the metasurface lens 6 includes a dielectric substrate 9, a front lens unit 7 and a back lens unit 8. The front lens unit 7 includes a T-shaped arm horizontal arm 7-1, a T-shaped arm vertical arm 7-2, a square ring 7-3 and a hollow square 7-4. The back lens unit 8 includes four crescents symmetrical about the center. Both the front lens unit 7 and the back lens unit 8 are centrally symmetrical structures, and their geometric centers coincide with the grid intersection points and are respectively placed on the front and back sides of the dielectric substrate 9, as shown in FIG. Figure 2 (a) and (b). The length of the T-arm horizontal arm 7-1 is s1 and the width is t, the length of the T-arm vertical arm 7-2 is s2 and the width is t, the side length of the square ring 7-3 is w1, and the side length of the square ring 7-4 is w2 (when w2=0, it means that there is no hollow 7-4 structure in the lens unit 7). In the four crescents of the reverse lens unit 8 that are symmetrical about the center, the outer radius of each crescent is r1, and the inner radius is r2, and the outer spacing of the two crescents is d1, and the inner spacing is d2.

[0017] Figure 3 A schematic diagram of the overall structure of a metasurface lens provided by the present invention, wherein the overall shape of the metasurface lens is a cross, wherein a pair of positive and negative lens units are placed in each square area in the figure, and the positive lens unit 7 and the negative lens unit 8 work together to shift the phase of the spatial plane electromagnetic wave, and as the geometric structure parameters of the positive lens unit 7 and the negative lens unit 8 change, the amplitude of the electromagnetic wave transmission is the same and the phase can continuously change between 0 and 2π, and the arrangement of the metasurface lens can focus the transmitted electromagnetic wave to a focus of a specific shape, acting on the effective working area of ​​the atomic gas chamber probe.

[0018] Preferably, the phase of the transmitted wave of the lens unit satisfies:

[0019]

[0020] Where λ is the working wavelength, f is the focal length, and fmn is the focus offset, x m and n Discretize the geometric center of each lens element.

[0021] When in use, the area where the detection light and the coupling light act together in the atomic gas chamber 4 is placed at the focus of the metasurface lens 6. When a plane wave is irradiated, the plane wave is converged to the focus through the metasurface lens 6, and its microwave electric field intensity will be enhanced and interact with the Rydberg state atoms in the atomic gas chamber 4. At this time, the transmittance of the atoms in the gas chamber to the detection light will change with the intensity and frequency of the microwave electric field, thereby producing an electromagnetic induced transparency and AT splitting (EIT-AT) effect. The detection light directly passes through the dichroic mirror 5 and is output to the photodetector through the third port 3 of the optical fiber. After photoelectric conversion, an electrical signal containing target information is obtained.

[0022] Example

[0023] The atomic gas chamber probe loaded with a metasurface lens provided in this embodiment is an antenna operating at 10 GHz. The metasurface lens can focus electromagnetic waves on the prepared Rydberg atomic linear effective area, which can better enhance the detection of weak electromagnetic signals.

[0024] The dielectric substrate of the metasurface lens is F4BM, with a relative dielectric constant of 3.65, a loss tangent of 0.0017, and a thickness of 2.9 mm. The lens units are printed on both sides of the dielectric substrate, and the entire lens is a single-layer structure.

[0025] The lens unit includes a front lens unit 7 and a back lens unit 8, and the period of each unit is p. Different geometric patterns are printed on the front and back of the dielectric substrate 9. The structure of the front lens unit 7 includes a T-arm horizontal arm 7-1, a T-arm vertical arm 7-2, a square ring 7-3 and a hollow 7-4.

[0026] The metasurface lens of this embodiment adopts a double-sided printed circuit board, which contains 67 lens units in total. Figure 3 The cross grid arrangement shown in the figure is composed of the unit phase distribution of the metasurface lens is determined by the following formula:

[0027]

[0028] Among them, the working wavelength λ is 30mm, the predetermined focal length is f=120mm, f mn is the focal point offset, in this embodiment -5mm≤f mn ≤5mm, the entire super surface is 160mm long and 130mm wide, and x in the formula m and n The discretization value of the geometric center of each lens unit is in the range of -80mm≤xn ≤80mm, -65mm≤y n ≤65mm, the unit spacing is p. Substituting these parameters into the above formula, the phase distribution of the metasurface lens can be obtained. According to the relationship between the geometric parameters of the front and back units of the metasurface lens and the modulation phase change, the geometric parameters of each lens unit in the metasurface lens and its corresponding phase offset can be obtained, such as Figure 4 As shown, the processing layout of the metasurface lens is finally drawn by programming with MATLAB software, and the metasurface lens can be prepared based on the obtained processing layout. The geometric dimensions of the front unit and the back unit vary according to the required phase of the lens, where p = 14mm, 4mm≤s1≤7mm, 5mm≤s2≤8mm, 0mm≤w1≤7mm, 0mm≤w2≤6mm, 0.5mm≤t≤2mm, 2mm≤r1≤4mm, 2mm≤r2≤6mm, 3mm≤d1≤8mm, 1mm≤d2≤4mm.

[0029] In this embodiment, Figure 3 There are four sizes of lens units in the complete lens shown, namely unit 10, unit 11, unit 12, and unit 13. Their structural parameters are shown in the following table (unit: mm):

[0030] s1 s2 w1 w2 t r1 r2 d1 d2 Unit 10 6.5 5.5 4.5 0 2.1 3.5 3.2 4.3 3.1 Unit 11 6.7 6.4 4.1 0.8 1.5 3.2 2.8 4.9 2.6 Unit 12 6.1 6.7 4.2 3.1 1.3 3.5 2.3 5.3 2.1 Unit 13 6.3 7.4 1.8 1.2 0.9 3.5 2.0 6.8 1.9

[0031] In order to test the performance of the designed and processed atomic antenna loaded with metasurface lens, the receiving performance of the metasurface lens of the above embodiment is firstly tested. The far-field measurement system is used to measure the radiation pattern in a microwave darkroom. Figure 5 As shown, the solid line 14 is the E-plane radiation pattern, and the dotted line 15 is the H-plane radiation pattern. It can be seen that the metasurface lens has good directivity for focusing electromagnetic waves, and the antenna gain can reach 18.75dBi.

[0032] Then, a comparative test was conducted on the electric field receiving performance when only the atomic antenna was used and when the metasurface lens was loaded. The target signal was a uniform plane electromagnetic wave with a radiation intensity of 1 V / m. The polarization direction was consistent with the polarization direction of the laser used to prepare the Rydberg atoms. The electric field strengths obtained using a separate atomic receiving antenna and the present invention were measured at 10 GHz and were 0.98 V / m and 8.1 V / m, respectively. The results show that the present invention can better focus the plane electromagnetic waves onto the atomic gas chamber, thereby responding to weaker electromagnetic signals.

[0033] The above includes the description of the preferred embodiment of the present invention, which is to explain the technical features of the present invention in detail, and is not intended to limit the invention to the specific form described in the embodiment. Other modifications and variations based on the main idea of ​​the present invention are also protected by this patent. The main idea of ​​the present invention is defined by the claims, not by the specific description of the embodiment.

Claims

1. An atomic gas chamber probe loaded with a metasurface lens, characterized in that: The invention comprises an atomic gas chamber probe and a metasurface lens for microwave focusing. The atomic gas chamber of the atomic gas chamber probe is arranged near the focus of the metasurface lens, and the shape of the focus of the metasurface lens is designed according to the effective action area of ​​the atomic gas chamber probe.

2. An atomic gas chamber probe loaded with a metasurface lens according to claim 1, characterized in that: The metasurface lens includes a dielectric substrate and a plurality of lens units, wherein the shape of the metasurface lens is a cross, lens units are arranged on both the front and back sides of the dielectric substrate, the phase shift range generated by the lens units covers 0 to 2π, and the lens units on the front and back sides of the dielectric substrate are arranged in a periodic array according to a grid distribution, and the focal shape formed can fit the effective working area of ​​the atomic antenna.

3. An atomic gas chamber probe loaded with a supersurface lens according to claim 2, characterized in that: The dielectric substrate is F4BM, with a relative dielectric constant of 3.65, a loss tangent of 0.0017, and a thickness of 2.9 mm.

4. An atomic gas chamber probe loaded with a supersurface lens according to claim 2, characterized in that: The phase of the transmitted wave of the lens unit satisfies: Where λ is the operating wavelength, f is the focal length, and f mn is the focus offset, x m and n Discretize the geometric center of each lens element.

5. An atomic gas chamber probe loaded with a supersurface lens according to claim 2, characterized in that: The lens unit comprises a front lens unit (7) and a back lens unit (8); the front lens unit (7) comprises a T-shaped arm horizontal arm (7-1), a T-shaped arm vertical arm (7-2), a square ring (7-3) and a hollow square (7-4); the back lens unit (8) comprises four crescents symmetrical about the center; the front lens unit (7) and the back lens unit (8) are both centrally symmetrical structures, the geometric centers of which coincide with the grid intersection points and are respectively arranged on the front and back sides of the dielectric substrate (9); the length of the T-shaped arm horizontal arm (7-1) is s1 and the width is t; the length of the T-shaped arm vertical arm (7-2) is s2 and the width is t; the side length of the square ring (7-3) is w1 and the side length of the hollow square (7-4) is w2; of the four crescents symmetrical about the center of the back lens unit (8), the outer radius of each crescent is r1 and the inner radius is r2; the outer spacing between the two crescents is d1 and the inner spacing is d2.

6. An atomic gas chamber probe loaded with a supersurface lens according to claim 5, characterized in that: A metasurface lens with 67 lens units, wherein structural parameters of the lens units satisfy p=14mm, 4mm≤s1≤7mm, 5mm≤s2≤8mm, 0mm≤w1≤7mm, 0mm≤w2≤6mm, 0.5mm≤t≤2mm, 2mm≤r1≤4mm, 2mm≤r2≤6mm, 3mm≤d1≤8mm, and 1mm≤d2≤4mm.

7. An atomic gas chamber probe loaded with a supersurface lens according to claim 6, characterized in that: A metasurface lens with 67 lens units, wherein the lens units have four sizes, and the structural parameters thereof are shown in the following table, unit: mm: 。

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