Superradiation pulse system

Abstract

The invention provides a superradiation pulse system, and belongs to the technical field of superradiation and pulse sources. The system comprises: a support layer; the zero-refractive-index metamaterial comprises a plurality of metal columns which are fixed on the supporting layer and are periodically arranged at intervals, and is used for realizing a zero-refractive-index environment aiming at the radiation frequency of the super-radiation pulse system; the plurality of dipole transmitting antennas are distributed in corresponding gaps in the zero-refractive-index metamaterial, are used as transmitting sources of superradiation, and are used for exciting a radiation field of superradiation in a superradiation pulse system to generate superradiation pulse signals; and the output end is used for outputting the super-radiation pulse signal with loss as low as possible. According to the invention, the super radiation with the emissivity increasing by multiple times in the quantum theory can be realized in the frequency band range from microwave to terahertz, and the limitation of the traditional super radiation on the equipment size smaller than one wavelength is liberated by the zero-refractive-index environment, so that the expansion of the super radiation not limited by linearity becomes possible.

Description

Technical Field

[0001] The present invention relates to the technical field of superradiance and pulse sources, and in particular to a superradiance pulse system based on a zero-refractive-index metamaterial. Background Art

[0002] Superradiance refers to the phenomenon that N identical atoms couple with each other to produce cooperative radiation, resulting in an N-fold increase in the emission rate. In contrast to incoherent radiation, a superradiant system will produce a pulse of light with a shorter half-wave width, whose peak intensity is proportional to the square of the number of emitters N, but the overall energy remains unchanged. Existing studies have explored the theory behind dipole-dipole interactions between superradiant atoms and observed superradiance in various artificial particle systems, such as ultracold nitrogen and quantum bits. However, these studies have placed strict requirements on the superradiance conditions, namely that all atoms should be within one wavelength, which greatly limits the scale of superradiant systems.

[0003] The spatial limitation of superradiance can be lifted by extending superradiance in a medium with a dielectric constant ε near zero (ENZ). By embedding multiple quantum emitters in an ENZ medium that describes a uniform distribution of spatial phase, the emitted photons can interact with each quantum emitter, thereby extending the spatial region of superradiance from one wavelength to a region much larger than one wavelength. Based on this principle, existing studies have proposed structures to achieve extended superradiance based on ENZ plasma channels, indium tin oxide films near the plasma frequency, and waveguides with cutoff wavelengths. However, the inherent ohmic loss of these metallic ENZ systems limits the superradiance power. In order to alleviate the ohmic loss, the prior art has proposed extended superradiance based on diamond ENZ metamaterials containing vacancy centers. However, this diamond ENZ metamaterial at visible light wavelengths still faces challenges in material purity and defect control, stress and strain management, and size and uniformity control. In addition, the emission wavelengths of all these quantum optical superradiance systems are limited by the energy levels of quantum emitters such as atoms, ions, and artificial atoms. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0005] To this end, the purpose of the present invention is to provide a superradiant pulse system based on zero-refractive-index metamaterials, which can realize superradiance in quantum theory with an emissivity increased by multiples of the source number in the microwave to terahertz frequency range. The zero-refractive-index environment frees traditional superradiance from the limitation of device size being less than one wavelength, thereby making it possible to extend superradiance without linear limitation.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions.

[0007] The present invention provides a superradiant pulse system, comprising:

[0008] Support layer;

[0009] A zero-refractive-index metamaterial, comprising a plurality of metal pillars fixed on the support layer and arranged at periodic intervals, for realizing a zero-refractive-index environment for the radiation frequency of the superradiant pulse system;

[0010] A plurality of dipole transmitting antennas are distributed in corresponding gaps in the zero-refractive-index metamaterial, serving as superradiance emission sources, to excite the superradiance radiation field of the superradiance pulse system to generate superradiance pulse signals;

[0011] The output end is used to output the super-radiant pulse signal with the lowest possible loss.

[0012] In some embodiments, the metal pillars in the zero-refractive-index metamaterial are made of the same material, and the electrical conductivity of the selected metal material should satisfy the requirement that the zero-refractive-index metamaterial can achieve zero refractive index within a set frequency band.

[0013] In some embodiments, the material of each metal column in the zero-refractive-index metamaterial is aluminum, gold, or copper to achieve a zero-refractive-index environment in the microwave frequency band.

[0014] In some embodiments, the cross-sectional shape of each metal pillar in the zero-refractive-index metamaterial has C4 symmetry.

[0015] In some embodiments, the refractive index of the interstitial medium between two adjacent metals in the zero-refractive-index metamaterial should satisfy the requirement that the zero-refractive-index metamaterial can reach zero refractive index within a set frequency band.

[0016] In some embodiments, the interstitial medium between two adjacent metals in the zero-refractive-index metamaterial is selected from air, foam or Teflon to achieve a zero-refractive-index environment in the microwave frequency band.

[0017] In some embodiments, the material of the support layer should have a refractive index equal to or close to that of the void medium in the zero-refractive-index metamaterial, and a plurality of holes are provided on the support layer for fixing the ends of each metal column in the zero-refractive-index metamaterial and embedding the dipole transmitting antenna.

[0018] In some embodiments, the center frequency of the dipole transmitting antenna is close to or equal to the characteristic frequency of the zero-refractive index metamaterial, so as to generate a superradiant pulse signal having a radiation frequency equal to the characteristic frequency of the zero-refractive index metamaterial.

[0019] In some embodiments, the output end uses an output antenna or an output waveguide;

[0020] The output antenna is a single dipole receiving antenna, and its end is embedded in the support layer;

[0021] The output waveguide is a single output waveguide, and the support layer, the zero-refractive-index metamaterial, and the dipole transmitting antenna are packaged by using a packaging structure, and a hole connected to the output waveguide is opened on the packaging structure.

[0022] In some embodiments, by adjusting the conductivity and structural characteristics of the metal pillars in the zero-refractive-index-exceeding material and the refractive index of the void medium, and selecting the dipole transmitting antenna whose center frequency is equal to or close to the characteristic frequency of the zero-refractive-index-exceeding material, a superradiant pulse system with a radiation frequency range from microwaves to terahertz is realized.

[0023] Compared with the prior art, the characteristics and beneficial effects of the present invention are:

[0024] The present invention discloses a superradiant pulse system based on a zero-refractive index metamaterial, and a high-peak power superradiant pulse source based on a periodic aluminum column low-loss zero-refractive index medium. The present invention achieves a zero-refractive index environment at a certain microwave frequency by adjusting the radius and periodicity of the metal column in the metamaterial, and can achieve a special environment in which the equivalent radiation wavelength is infinite in the material. In this environment, by using multiple dipole transmitting antennas as radiation sources, extended superradiance that is not limited by the size of the device and the energy level of the quantum emitter can be achieved. After packaging this structure, a high-power microwave superradiant pulse system can be formed, which has multiple incoherent antenna transmitting sources as input and an output peak power that increases as the square of the number of radiation sources.

[0025] The advantages of the present application will be given in part in the following description, and in part will become apparent from the following description, or will be understood through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a stereoscopic diagram of a superradiant pulse system provided by an embodiment of the present invention, and the supporting layer in the system is not shown in the diagram.

[0027] Figure 2 It is a top view of a superradiant pulse system provided by an embodiment of the present invention.

[0028] Figure 3 This is a comparison diagram of the changes in superradiance and general radiation intensity over time generated by a superradiance pulse system provided by an embodiment of the present invention.

[0029] Figure 4 The present invention provides a quantitative result of the effectiveness test of a super-radiant pulse system in simulation and experiment.

[0030] In the figure:

[0031] 1. Zero refractive index metamaterial, 2. Dipole transmitting antenna, 3. Output end, 4. Support layer.

[0032] Specific implementation method

[0033] In order to make the purpose, technical solution and advantages of the present invention more clear, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other arbitrarily without conflict.

[0034] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from the description. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0035] The following is a further description of specific examples of the present invention with reference to the accompanying drawings: Example

[0036] See also Figure 1 , Figure 2 , a superradiant pulse system provided by an embodiment of the present invention is used to generate a superradiant pulse signal in a microwave frequency band, the system comprising:

[0037] Support layer 4;

[0038] The zero-refractive-index metamaterial 1 comprises a plurality of metal pillars fixed on a support layer 4 and arranged at periodic intervals, and is used to realize a zero-refractive-index environment for the radiation frequency of the superradiant pulse system;

[0039] A plurality of dipole transmitting antennas 2 are distributed in corresponding gaps in the zero-refractive-index metamaterial 1, and serve as superradiance emission sources to excite the superradiance radiation field of the present superradiance pulse system, thereby generating superradiance pulse signals in the microwave frequency band;

[0040] The output terminal 3 is used to output a superradiant pulse signal with the lowest possible loss.

[0041] In some embodiments, the material of the support layer 4 should have a refractive index equal to or close to that of the void medium in the zero-refractive-index metamaterial 1. In a specific embodiment of the present invention, an acrylic plate is selected as the support layer 4. The support layer 4 is provided with a plurality of holes for fixing the ends of the metal columns in the zero-refractive-index metamaterial 1 and embedding the dipole transmitting antenna 2.

[0042] In some embodiments, the material of each metal column in the zero-refractive index metamaterial 1 is the same, and the conductivity of the selected metal material should meet the requirement that the zero-refractive index metamaterial 1 can reach zero refractive index within a set frequency band. For example, in order to achieve a zero-refractive index environment in the microwave frequency band of an embodiment of the present invention, aluminum, gold, copper, etc. can be selected as the material of the metal column. The cross-section of each metal column adopts a circular cross-sectional shape or other cross-sectional shapes with C4 symmetry. The gap medium between two adjacent metal columns should select a medium with a refractive index within a suitable range, so that the zero-refractive index metamaterial 1 reaches zero refractive index within a set frequency band. For example, in order to achieve a zero-refractive index environment in the microwave frequency band of an embodiment of the present invention, the gap medium between two adjacent metal columns can be air, foam, or Teflon, etc.

[0043] Furthermore, by controlling the radius and spatial period of the metal column in the zero-refractive-index metamaterial 1, the equivalent refractive index of the metamaterial is equal to or close to zero within a certain microwave bandwidth, and the characteristic frequency of the zero-refractive-index metamaterial 1 (i.e., the frequency at which the equivalent refractive index is zero) corresponds to the center frequency of the dipole transmitting antenna 2. By adjusting the radius and spatial period of the metal column in the metamaterial, the characteristic frequency of the metamaterial can be tuned, thereby changing the frequency of the dipole transmitting antenna 2 and achieving microwave super-radiation over a larger range. It should be noted that when regulating the zero-refractive-index metamaterial 1, the height change of the metal column is not considered. Since the height has no obvious effect on the characteristic frequency of the metamaterial, the height of the metal column is generally set to a fixed amount that is much larger than the radius and spatial period of the metal column.

[0044] In some embodiments, the number of dipole transmitting antennas 2 contained in the present superradiant pulse system is N, and the N dipole transmitting antennas 2 are all commercial dipole transmitting antennas, and the center frequency of each dipole transmitting antenna 2 should be close to or equal to the characteristic frequency of the zero-refractive index metamaterial 1, so as to generate a superradiant pulse signal with a radiation frequency equal to the characteristic frequency of the zero-refractive index metamaterial 1. The value of N can be selected according to the size of the zero-refractive index metamaterial 1. In order to achieve a superradiant pulse with the highest possible peak power, the number of dielectric gaps filled with the zero-refractive index metamaterial 1 should be taken as the standard. It should be noted that when placing the dipole transmitting antenna 2 in the gap of the zero-refractive index metamaterial 1, it is necessary to avoid physical contact between the dipole transmitting antenna 2 and the metal column in the zero-refractive index metamaterial 1 to cause a short circuit.

[0045] In some embodiments, the output terminal 3 may be an output antenna or an output waveguide. Furthermore, in order to make the output energy more concentrated, a dipole receiving antenna or an output waveguide should be used as the output terminal 3. If a dipole receiving antenna is selected as the output terminal 3, it can be directly placed in the corresponding gap of the zero-refractive-index metamaterial 1, and a hole for embedding and fixing the dipole receiving antenna should be reserved in the support layer 4; if a waveguide is selected as the output terminal 3, it is necessary to first Figure 1 The structure shown is encapsulated with metal on all sides, and then a hole is opened on one side of the metal encapsulation (the shape of the hole matches the cross-sectional shape of the waveguide used, such as a rectangular hole) and then connected to a standardized waveguide (such as a rectangular waveguide) corresponding to the pulse frequency of the superradiant pulse system.

[0046] The effectiveness of the embodiment of the present invention is verified below. First, a simulation analysis is performed on the super-radiant pulse system of the present embodiment, and then an actual experimental test is performed, which are described as follows:

[0047] 1. Simulation analysis

[0048] The embodiment of the present invention uses the electromagnetic simulation software FDTD to complete the simulation analysis before the experiment. First, a zero-refractive index metamaterial 1 is constructed in FDTD, which is composed of a periodic metal column array structure, and air is used as the gap material. Then a dipole transmitting antenna 2 is embedded in the gap of the zero-refractive index metamaterial 1. With the help of FDTD software, the phase characteristics of the field of the entire structure along the height direction of the metal column under different dipole antenna emission wavelengths can be analyzed. If it can be observed that the phase characteristics do not change with the spatial position near a certain emission wavelength, it proves that a zero-refractive index environment has been achieved. This is because in a zero-refractive index environment, the equivalent radiation wavelength of the electromagnetic wave is infinite, so the phase presents the characteristics of being both positive and negative. The emission wavelength at this time is the characteristic wavelength, and the corresponding frequency is the characteristic frequency of the zero-refractive index metamaterial 1. After determining the characteristic frequency, the time curve of the structural radiation field intensity after embedding N (N>1) dipole transmitting antennas 2 in the structure can be compared. See. Figure 3In theory, the radiation field intensity time curve b of a single dipole antenna is an exponential decay field with a pulse width of τ, and superradiance achieves superradiance by exciting the dipole-dipole interaction between multiple dipole transmitting antennas 2. Compared with the radiation field intensity time curve b of a single dipole antenna, the peak field intensity of the radiation field intensity time curve a of the superradiance pulse system of the embodiment of the present invention is enhanced by N times, and the pulse width is reduced to τ / N. Therefore, in the simulation software, if it can be observed that the peak value of the radiation field intensity time curve at the characteristic frequency is higher than that at the non-characteristic frequency, and the decay is faster, the occurrence of the superradiance phenomenon can be qualitatively proved. Then further quantitative analysis is performed to explore the quantitative relationship between the peak power of the superradiance pulse system and the number of transmitting sources N. In the simulation experiment, a dipole receiving antenna is used as the output terminal 3, the position of the dipole receiving antenna can be fixed, and then a gradually increasing number of dipole transmitting antennas 2 are placed around the dipole receiving antenna on a circle with a fixed radius. By comparing the power changes of the dipole receiving antennas in the case of different numbers of dipole transmitting antennas 2, quantitative measurement can be completed.

[0049] After numerical simulation, the dimension information of the zero-refractive-index metamaterial 1 finally adopted in the embodiment of the present invention is as follows: the radius of the metal column r=2 mm, the periodicity a=20 mm, the column height l=200 mm, and the number of metal columns is 11×11=121, thereby realizing a zero-refractive-index environment with a characteristic frequency of 5.3 GHz-5.4 GHz within a space range of 0.25×0.25×0.2 cubic meters. The dipole transmitting antenna 2 used in the embodiment of the present invention is a commercially purchased 1 / 4 wavelength dipole antenna with a center frequency of 5 GHz and a bandwidth range of about 1 GHz, which basically meets the requirements of the present invention. The embodiment of the present invention selects a dipole receiving antenna as the output terminal 3. Compared with the output waveguide, the dipole receiving antenna has the characteristics of being light and easy to move, and is more suitable for the needs of the effectiveness verification experiment.

[0050] 2. Actual experimental test

[0051] Using the superradiant pulse system determined by the above-mentioned simulation molecules, the effectiveness of the superradiant quantitative results can be explored through a vector network analyzer in actual experiments. Specifically, the output of port 1 of the vector network analyzer is connected to the power divider and then to 8 identical dipole transmitting antennas 2, so as to keep the radiation characteristics of the 8 dipole transmitting antennas 2 the same, and then the dipole transmitting antennas 2 are placed one by one in the gaps of the zero-refractive index metamaterial 1, so that the number of dipole transmitting antennas 2 in the zero-refractive index structure 1 increases from 1 to 8. In this process, it is necessary to keep the distance from the 8 dipole transmitting antennas 2 to the output terminal 3 the same, so as to ensure that the field strength of the radiation field of each dipole transmitting antenna 2 after attenuation when reaching the output terminal 3 is the same, avoiding the interference of the radiation field strength attenuation characteristics with distance on the quantitative measurement. Port 2 of the vector network analyzer is connected to the dipole receiving antenna located at the center of this superradiant pulse system, and the dipole receiving antenna serves as the output terminal 3 to complete the measurement of the superradiant pulse signal. By recording the S21 parameter (the parameter is the ratio of the 2-port input power to the 1-port output power) of the vector network analyzer and performing certain data processing, the quantitative results of the peak power of the radiation field of the superradiant pulse system can be obtained. Figure 4 This is a set of quantitative results obtained by testing the effectiveness of the microwave superradiant pulse system of the embodiment of the present invention, where the horizontal axis is the number of dipole transmitting antennas 2, and the vertical axis is the normalized peak power. The normalized peak power of the ideal superradiant pulse system should be in a square relationship with the number of dipole transmitting antennas 2. The dotted line in the figure is the theoretical square relationship curve. The figure shows that the simulation results (triangle marks) and the experimental results (square marks) are both distributed near the theoretical square relationship curve, thereby verifying the effectiveness of the embodiment of the present invention.

[0052] It should be added that the frequency band of the superradiant pulse generated by the superradiant pulse system of the present invention can be adjusted by changing the conductivity, radius, length and periodicity of the metal column array and the refractive index of the void medium, thereby constructing a zero refractive index environment with a characteristic frequency ranging from microwave to terahertz. At the same time, by selecting a dipole transmitting antenna 2 whose center frequency is equal to or close to the characteristic frequency. Therefore, the present invention can be extended from a microwave frequency band embodiment to a terahertz superradiant pulse system.

[0053] It can be understood that the superradiant pulse system provided by the present invention controls the radius and spatial period of the zero-refractive-index metamaterial so that its equivalent refractive index is equal to or close to zero within a certain microwave bandwidth, and the characteristic frequency of the system (i.e., the frequency with an equivalent refractive index of zero) corresponds to the center frequency of the dipole transmitting antenna. By adjusting the radius and spatial period of the metamaterial, its characteristic frequency can be tuned, so that the frequency of the pulse emission source can be changed to achieve superradiance over a larger range. In view of the size restriction that all atoms of superradiance should be within one wavelength, the present invention introduces a zero-refractive-index environment to achieve an equivalent refractive index of zero, that is, the equivalent radiation wavelength is infinite, thereby expanding the linearity of the superradiant system; in view of the fact that the emission wavelength of superradiance is limited by the energy levels of quantum emitters such as atoms, ions and artificial atoms, a dipole antenna is innovatively used instead of a quantum emitter as a radiation source, thereby expanding the emission wavelength range of the superradiant system. The superradiant pulse system of the present invention has the characteristics of expandable peak power, expandable radiation wavelength, and stable and easy packaging.

[0054] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A superradiant pulse system, characterized in that: include: Support layer; A zero-refractive-index metamaterial, comprising a plurality of metal pillars fixed on the support layer and arranged at periodic intervals, for realizing a zero-refractive-index environment for the radiation frequency of the superradiant pulse system; A plurality of dipole transmitting antennas are distributed in corresponding gaps in the zero-refractive-index metamaterial, serving as superradiance emission sources, to excite the superradiance radiation field of the superradiance pulse system to generate superradiance pulse signals; The output end is used to output the super-radiant pulse signal with the lowest possible loss.

2. The superradiant pulse system according to claim 1, characterized in that: The metal pillars in the zero-refractive-index metamaterial are made of the same material, and the electrical conductivity of the selected metal material should satisfy the requirement that the zero-refractive-index metamaterial can achieve zero refractive index within a set frequency band.

3. The superradiant pulse system according to claim 1, characterized in that: The material of each metal column in the zero-refractive-index metamaterial is aluminum, gold or copper to achieve a zero-refractive-index environment in the microwave frequency band.

4. The superradiant pulse system according to claim 1, characterized in that: The cross-sectional shape of each metal pillar in the zero-refractive-index metamaterial has C4 symmetry.

5. The superradiant pulse system according to claim 1, characterized in that: The refractive index of the interstitial medium between two adjacent metals in the zero-refractive-index metamaterial should satisfy the requirement that the zero-refractive-index metamaterial can reach zero refractive index within a set frequency band.

6. The superradiant pulse system according to claim 1, characterized in that: The gap medium between two adjacent metals in the zero-refractive-index metamaterial is selected from air, foam or Teflon to achieve a zero-refractive-index environment in the microwave frequency band.

7. The superradiant pulse system according to claim 1, characterized in that: The material of the support layer should have a refractive index equal to or close to that of the void medium in the zero-refractive-index metamaterial. The support layer is provided with a plurality of holes for fixing the ends of the metal columns in the zero-refractive-index metamaterial and embedding the dipole transmitting antenna.

8. The superradiant pulse system according to claim 1, characterized in that: The center frequency of the dipole transmitting antenna is close to or equal to the characteristic frequency of the zero-refractive-index metamaterial, so as to generate a superradiant pulse signal with a radiation frequency equal to the characteristic frequency of the zero-refractive-index metamaterial.

9. The superradiant pulse system according to claim 1, characterized in that: The output end adopts an output antenna or an output waveguide; The output antenna is a single dipole receiving antenna, and its end is embedded in the support layer; The output waveguide is a single output waveguide, and the support layer, the zero-refractive-index metamaterial, and the dipole transmitting antenna are packaged by using a packaging structure, and a hole connected to the output waveguide is opened on the packaging structure.

10. The superradiant pulse system according to any one of claims 1 to 9, characterized in that: By adjusting the conductivity and structural characteristics of the metal columns in the zero-refractive-index-exceeding material and the refractive index of the void medium, and selecting the dipole transmitting antenna whose center frequency is equal to or close to the characteristic frequency of the zero-refractive-index-exceeding material, a super-radiant pulse system with a radiation frequency range from microwaves to terahertz is realized.

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