A terahertz continuous metasurface device based on magnetic surface plasmons and application thereof

Abstract

A kind of terahertz continuous metasurface device based on magnetic surface plasmon and its application, the device with electric opaque layer, dielectric layer, magnetized semiconductor layer from top to bottom sequentially horizontal superposition unidirectional waveguide as substrate, the thickness of electric opaque layer is modulated by continuous function model, and is formed in waveguide by introducing metal sheet array.This application also relates to the application of the device in generating airy beam.This application supports terahertz unidirectional transmission based on magnetic surface plasmon.This application can realize phase control by adjusting the height of metal sheet, and can realize continuous amplitude control by continuously modulating the thickness of radiation layer through continuous function model.Compared with super-structured surface relying on discrete structure, this application can reduce energy loss and wavefront distortion, and improve beam control precision and stability.Relying on the above characteristics, this application generates one-dimensional finite airy beam with self-acceleration, no diffraction and self-healing characteristics.

Description

Technical Field

[0001] This invention relates to the field of terahertz technology and metasurfaces, specifically to a terahertz continuous metasurface device based on magnetic surface plasmons and its application in generating Airy beams. Background Technology

[0002] Surface plasmon polaritons (SPPs) are mixed electron-photon excited states at the metal-dielectric interface that can propagate like waves. SPPs can overcome the diffraction limit, confining electromagnetic fields to a range much smaller than the wavelength, achieving so-called subwavelength confinement. However, the plasma frequency of metals is typically in the ultraviolet band, so SPPs on metal surfaces are only suitable for the visible light band. Using semiconductors, or plasma materials, visible light SPP manipulation technology can be directly analogous to the terahertz band. Crucially, semiconductors are also rotatable electromagnetic materials; under the influence of an external magnetic field, the time-reversal symmetry of the system is broken, supporting non-reciprocal SPPs, i.e., so-called unidirectional surface magnetic-plasmons (USMPs). USMP-based unidirectional electromagnetic modes not only have simple configurations but also easily achieve broadband bandwidth, making them highly suitable for miniaturization.

[0003] Airy beams, as a typical non-diffractive beam, possess unique propagation characteristics. Compared to conventional Gaussian beams, Airy beams not only maintain a stable transverse intensity distribution during propagation in free space but also exhibit self-acceleration and self-healing properties. That is, the main lobe of the beam can propagate along a predetermined curved trajectory and automatically recover its original shape after encountering partial obstruction or interference. These characteristics make Airy beams highly promising for applications in optical manipulation, particle trapping, imaging, optical communication, and terahertz wave modulation.

[0004] Currently, most common Airy beam generation methods rely on discrete optical or electromagnetic structures, such as phase gratings, spatial light modulators, phase plates, or discrete antenna arrays. Although these methods can achieve an approximate structure of an Airy beam, they generally suffer from the following shortcomings: First, amplitude and phase modulation often require separate devices, leading to high system complexity and cumbersome manufacturing processes; second, discrete structures introduce significant energy loss and waveform distortion, making it difficult to obtain high-fidelity Airy beams; third, the robustness and stability of the beam decrease significantly in the presence of backscattering or defects in traditional waveguides, which is detrimental to high-precision applications.

[0005] Furthermore, most current research on Airy beams focuses on the optical band (visible light, near-infrared) and the microwave band. Traditional methods for generating Airy beams (such as spatial light modulators, phase gratings, and optical holography) are difficult to implement directly in the terahertz band due to the lack of efficient phase modulators and integrated structures.

[0006] Compared to optical and microwave sources, terahertz sources have lower power and insufficient device fabrication precision, which limits the exploration of Airy beams in this frequency band.

[0007] Chinese patent application CN117423996A discloses a "leaking metasurface and method based on unidirectional electromagnetic modes," which is a unidirectional transmission waveguide structure based on magnetic surface plasma realized in the microwave band. Its radiation depends on periodic openings in the waveguide structure, and its modulation is discrete. Furthermore, the described leaky metasurface can only adjust the phase, not the amplitude. Therefore, it cannot achieve the energy distribution required for Airy beams.

[0008] Chinese patent application CN119864622B discloses a "terahertz three-dimensional unidirectional transmission waveguide based on magnetic surface plasma". Although this unidirectional transmission waveguide can achieve terahertz unidirectional transmission, its dispersion curve cannot cross the optical cone line, especially the electromagnetic mode wave vector supported by the waveguide. k ≠0, does not support lateral radiation.

[0009] Therefore, there is an urgent need for a terahertz continuous metasurface that can take into account robustness, continuous amplitude modulation, and easy integration, in order to overcome the shortcomings of existing technologies and open up new avenues for the research of terahertz controllable optical field modulation. Summary of the Invention

[0010] This invention aims to overcome the shortcomings of existing technologies and provide a terahertz continuous metasurface device based on magnetic surface plasma and its application in generating Airy beams.

[0011] The first aspect of this invention provides a terahertz continuous metasurface device based on magnetic surface plasmons for generating a one-dimensional finite Airy beam with self-acceleration, diffraction-free and self-healing properties. The invention not only achieves phase modulation by adjusting the height of the metal sheet, but also reduces energy loss and distortion through a continuous function model, simplifies the device design and manufacturing process, and expands the application prospects of magnetic surface plasmons in the field of terahertz controllable optical field modulation.

[0012] A terahertz continuous metasurface device based on magnetic surface plasmons is used to generate a one-dimensional finite Airy beam with self-acceleration, diffraction-free, and self-healing properties. An electrically opaque layer, a dielectric layer, and a magnetized semiconductor layer, extending along the direction of unidirectional waveguide propagation, are horizontally stacked sequentially from top to bottom to form the substrate of the unidirectional waveguide. The direction of unidirectional waveguide propagation is defined as the X-direction, the direction perpendicular to the X-direction on the horizontal plane is defined as the Y-direction, and the direction perpendicular to the horizontal plane is defined as the Z-direction. The electrically opaque layer, dielectric layer, and magnetized semiconductor layer are homogeneous in the Y-direction.

[0013] The magnetized semiconductor is a gyroelectric material. Under the action of a static magnetic field, its relative permittivity is converted into a tensor form, which endows the waveguide with non-reciprocal properties, thereby supporting terahertz unidirectional transmission based on magnetic surface plasma.

[0014] The electrically opaque layer serves as a radiation layer. Its bottom surface is flat, and its upper surface exhibits a continuous function model along the X direction. Its thickness is modulated by the continuous function model. The continuous function model is based on the functional relationship between the radiation layer thickness and radiation loss. The radiation layer thickness distribution is determined by combining the target energy distribution characteristics of a one-dimensional finite Airy beam. Then, the continuous thickness modulation function of the radiation layer is obtained by fitting, thereby realizing the continuous control of the amplitude of the radiated electromagnetic wave.

[0015] It also includes a metal sheet array composed of several metal sheets perpendicular to the X direction aligned with each other. The metal sheets pass through the electrically opaque layer and the dielectric layer sequentially from the baseline to the magnetized semiconductor layer. The X-direction position of the metal sheets corresponds to the zero point of the target energy distribution function. The total height of the metal sheets is adapted to the phase modulation of the waveguide mode.

[0016] The upper surface of the electrically opaque layer is the radiating surface.

[0017] Furthermore, the magnetized semiconductor in a static magnetic field Under its influence, its relative permittivity is transformed into a tensor form, thereby endowing the waveguide with non-reciprocal properties and enabling terahertz unidirectional transmission based on magnetic surface plasmons. Its relative permittivity tensor is... ,in , , ;in The plasma angular frequency of the magnetized semiconductor. The electron cyclotron frequency is determined by the applied static magnetic field. Decide, The relative permittivity of the magnetized semiconductor at high frequencies, and the plasma frequency of the magnetized semiconductor. .

[0018] Furthermore, the dispersion curve of the unidirectional waveguide completely spans the optical cone line, supporting the wave vector. k=0, possessing continuous lateral radiation characteristics, the energy of the supported waveguide modes is radiated into free space through an electrically opaque layer (as a radiation layer).

[0019] Preferably, the functional relationship between the thickness of the radiation layer and the radiation loss is as follows: ,in For radiation loss, d The thickness of the radiating layer is given. A and B are parameters determined by the structural characteristics of the magnetized semiconductor, dielectric, and radiating layer.

[0020] Preferably, the continuous thickness modulation function of the radiation layer obtained by fitting is obtained using polynomial fitting, and its form is as follows: .

[0021] Preferably, the target energy distribution of the one-dimensional finite Airy beam has the following form: ,in It is the attenuation factor. The scaling factor in the X direction. , c It is the speed of light.

[0022] Furthermore, the total height of the metal sheet , It is the reference thickness of the radiation layer. For the thickness of the dielectric layer, This represents the height of the metal sheet within the magnetized semiconductor. The reference line is at the same horizontal level as the upper surface of the radiating layer when its reference thickness is reached. The reference thickness of the radiating layer is... Defined as: when radiation loss The thickness of the radiation layer when it approaches zero (or decreases to a negligible level).

[0023] Furthermore, the total height of the metal sheet is adapted to the phase modulation of the waveguide mode by adjusting the height of the metal sheet within the magnetized semiconductor. To determine its total height This enables phase modulation of the waveguide mode, obtaining the desired stepped phase distribution, and replacing traditional phase modulators.

[0024] A second aspect of the present invention provides an Airy beam generation method for terahertz continuous metasurface devices based on magnetic surface plasmons, comprising the following steps:

[0025] Step 1: Construct a unidirectional magnetic surface plasmonic waveguide with continuous lateral radiation characteristics;

[0026] Step 2: Establish the thickness of the radiation layer With radiation loss The functional relationship;

[0027] Step 3: Determine the target energy distribution function of the one-dimensional Airy beam in the lateral radiation region. ;

[0028] Step 4: Optimize the radiation energy distribution using an iterative algorithm to make the radiation energy distribution approximate the target energy distribution, thereby obtaining the radiation energy distribution function. ;

[0029] Step 5: Based on the radiation energy distribution function and the relationship between radiation layer height and radiation loss, obtain the continuous thickness modulation function of the radiation layer. This allows for continuous modulation of the amplitude;

[0030] Step 6: Introduce a metal sheet array in the waveguide, with its position corresponding to the zero point of the target energy distribution function, to obtain the required stepped phase distribution.

[0031] Step 7: Generate Airy beam.

[0032] Preferably, the radiation energy distribution function described in step four With the target energy distribution function A specific relationship needs to be satisfied, defined as: ,in It is a global attenuation factor used to control the total radiated energy of a unidirectional waveguide.

[0033] Preferably, the iterative algorithm in step four employs an error feedback method, updating the radiation energy distribution based on the difference between the actual radiation energy distribution and the target energy distribution until a predetermined error threshold is reached. The iterative formula is as follows: ,in For the iterative learning rate, To prevent small constants from being divided by zero, This represents the distribution of radiant energy.

[0034] Advantages of this invention: This invention not only achieves phase modulation by adjusting the height of the metal sheet, but also achieves continuous amplitude modulation by continuously modulating the thickness of the radiating layer through a continuous function model. This overcomes the limitations of traditional metasurfaces that rely on discrete structures for electromagnetic wave modulation. This hybrid modulation mechanism eliminates the need for an additional phase modulator, significantly improving the device's integration and making the overall structure more compact and easier to miniaturize. Furthermore, thanks to the continuous function model and the immune backscattering characteristics of the unidirectional magnetic surface plasmonic waveguide, the accuracy, stability, and trajectory controllability of Airy beam generation are improved, expanding the application prospects of magnetic surface plasmonic waves in the field of terahertz controllable optical field modulation. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of the terahertz continuous metasurface device of the present invention.

[0036] Figure 2(a) is a dispersion relation diagram of the unidirectional waveguide of the present invention, Figure 2(b) is a schematic diagram of the unidirectional waveguide transmission of the present invention, and Figure 2(c) is a schematic diagram of the unidirectional waveguide transmission of the present invention with obstacles.

[0037] Figure 3 This is a graph showing the relationship between the thickness of the radiation layer and radiation loss in this invention.

[0038] Figure 4 This invention relates to the normalized energy distribution of Airy beams along the X-direction.

[0039] Figure 5 This invention relates to the phase distribution of the Airy beam along the X-direction.

[0040] Figure 6(a) shows the effect of the Airy beam of the present invention, and Figure 6(b) shows the effect of the self-healing of the Airy beam of the present invention. Detailed Implementation

[0041] The embodiments of the present invention will be described in further detail below.

[0042] Example 1

[0043] This embodiment provides a terahertz continuous metasurface device based on magnetic surface plasmons, the specific structure of which is as follows: Figure 1 As shown.

[0044] First, a unidirectional waveguide is constructed by horizontally stacking an electrically opaque layer, a dielectric layer, and a magnetized semiconductor layer, extending along the direction of unidirectional waveguide propagation. The waveguide exhibits continuous lateral radiation characteristics. The waveguide propagation direction is the X-direction, the direction perpendicular to the X-direction on the horizontal plane is the Y-direction, and the direction perpendicular to the horizontal plane is the Z-direction. The electrically opaque layer, dielectric layer, and magnetized semiconductor layer are uniform in the Y-direction.

[0045] The waveguide's magnetized semiconductor layer is made of indium antimonide, the dielectric layer is made of silicon, and the electrically opaque layer is made of gallium arsenide. The indium antimonide magnetized semiconductor material operates in a static magnetic field. Under the influence of this process, its dielectric constant is transformed into a tensor form, endowing the waveguide with non-reciprocal properties, enabling terahertz unidirectional transmission based on magnetic surface plasmons, as shown in Figure 2(b). Its relative dielectric tensor is... ,in , , ;in The plasma angular frequency of the magnetized semiconductor. The electron cyclotron frequency is determined by the applied static magnetic field. Decide, The relative permittivity of the magnetized semiconductor at high frequencies, and the plasma frequency of the magnetized semiconductor. The high-frequency relative permittivity of the electrically opaque layer material, gallium arsenide. Plasma angular frequency .

[0046] The dispersion curve of the constructed unidirectional waveguide can completely span the optical cone, supporting wave vector propagation. k =0, possessing continuous lateral radiation characteristics, the energy of the supported waveguide modes can be directly radiated into free space through the electrically opaque layer (as a radiation layer). Furthermore, by adjusting the silicon layer thickness... To adjust the wave vector k To support continuous lateral radiation, the wave vector must be satisfied. k= 0, at this time The dispersion relation of the unidirectional waveguide under these parameters is shown in Figure 2(a). k= At 0, the operating frequency is 2.30THz.

[0047] The electrically opaque layer serves as the radiation layer. Its bottom surface is flat, and its upper surface exhibits a continuous function model along the X-direction. The upper surface of the electrically opaque layer is the radiation surface.

[0048] Furthermore, the relationship between the thickness of the radiation layer and the radiation loss was obtained: ,in For radiation loss, d The thickness of the radiating layer is given by A and B. A and B are parameters determined by the structural characteristics of the magnetized semiconductor, dielectric, and radiating layer. In this embodiment, A = 1.42 and B = 0.024 (both are normalized dimensionless parameters). The functional relationship is as follows: Figure 3 As shown.

[0049] Furthermore, the target energy distribution function of the Airy beam along the X-direction is determined, such as... Figure 4 As shown. In this embodiment, for a one-dimensional finite-energy Airy beam, it can be: ,in =0.08 is the attenuation factor. The scaling factor in the X direction. , c It is the speed of light.

[0050] Furthermore, the reference thickness of the radiation layer is set as... At this time, radiation loss Approaching zero (or decreasing to a negligible level). In this embodiment, we selected the coordinate range [-20]. 4 ] represents the modulation interval of the radiation layer, and sets when At that time, the thickness of the radiation layer is the reference thickness. In addition, the non-modulation region [4] ,12 The thickness of the radiation layer is set to the reference thickness. .

[0051] Furthermore, based on the functional relationship between the radiation layer thickness and radiation loss, and combined with the target energy distribution characteristics of a one-dimensional finite Airy beam, the radiation layer thickness distribution is determined. Then, a continuous thickness modulation function of the radiation layer is obtained through fitting, achieving continuous control of the amplitude of the radiated electromagnetic wave. In this embodiment, to precisely control the relationship between the radiation layer thickness and the x-axis coordinate, within the modulation interval, the continuous thickness modulation function... A seven-segment polynomial fitting model was employed, which fits the target energy distribution function to each segment. The thickness modulation function is fitted to the interval between adjacent zeros corresponding to each peak to ensure that the thickness distribution function within each interval matches the corresponding energy distribution characteristics. Following the order from the main peak to the secondary peak, the fitted continuous thickness modulation function is:

[0052] The specific parameters are shown in Table 1. The actual radiation energy distribution is as follows: Figure 4 As shown.

[0053] Furthermore, a metal sheet array is formed by aligning several metal sheets perpendicular to the X-direction. These metal sheets sequentially pass through an electrically opaque layer and a dielectric layer, extending from a baseline to a magnetized semiconductor layer. The X-direction positions of the metal sheets correspond to the zero points of the target energy distribution function. The total height of the metal sheets is adapted to the phase modulation of the waveguide mode. In this embodiment, the target energy distribution function has seven zero points to the left of the main peak, therefore only six metal sheets are needed. Further, the height of the metal sheets within the magnetized semiconductor layer can be adjusted... To determine its total height This enables phase modulation of the waveguide mode, obtaining the desired stepped phase distribution, as shown in the figure. Figure 5 As shown, the total height of the metal sheet is from the main peak to the secondary peak. The distribution is shown in Table 2. The width of the metal sheet in the X direction is... This can reduce the impact of abrupt phase changes on the overall phase distribution.

[0054] Example 2

[0055] An application of the terahertz continuous metasurface device based on magnetic surface plasmons as described in Example 1, specifically a method for generating an Airy beam, includes the following steps:

[0056] Step 1: Construct a unidirectional magnetic surface plasma waveguide with continuous lateral radiation characteristics as described in Example 1.

[0057] Step 2: Establish the radiation layer thickness as described in Example 1 With radiation loss The functional relationship, , where A=1.42 and B=0.024 (both are normalized dimensionless parameters).

[0058] Step 3: Determine the target energy distribution function of the one-dimensional Airy beam in the lateral radiation region as described in Example 1: ,in =0.08, .

[0059] Step 4: Optimize the radiation energy distribution using an iterative algorithm to make the radiation energy distribution approximate the target energy distribution, thereby obtaining the radiation energy distribution function. ;

[0060] Based on the functional relationship between radiation layer thickness and radiation loss, and combined with the target energy distribution characteristics, the initial radiation layer thickness distribution is determined, and then the initial radiation energy distribution is calculated based on the initial thickness distribution. In this embodiment, to eliminate the influence of absolute energy values, the focus is on comparing the distribution shape. The initial radiation energy distribution and the target energy distribution are normalized, and the radiation energy distribution is updated based on the difference in the normalized energy distribution until the shape of the radiation energy distribution approximates the target energy distribution. The correlation coefficient between the two normalized distribution sequences is then calculated. R When the value is greater than 0.999, the iteration stops. The optimized normalized radiation energy distribution and the target energy distribution are as follows: Figure 4 As shown. The radiation energy distribution function is... With the target energy distribution function They satisfy a specific relationship, specifically: ,in This is the global attenuation factor, used to control the total radiated energy of the unidirectional waveguide. The iterative formula is defined as: ,in For the iterative learning rate, To prevent small constants from being divided by zero, For the distribution of radiant energy, all distributions are normalized.

[0061] Step 5: Based on the radiation energy distribution function and the relationship between radiation layer height and radiation loss, obtain the continuous thickness modulation function of the radiation layer. This achieves continuous amplitude modulation. The fitted continuous thickness modulation function is as described in Example 1, and has the following form:

[0062] The parameters are shown in Table 1.

[0063] Step Six: Introduce a metal sheet array as described in Example 1 into the waveguide, positioned to correspond to the zero of the target energy distribution function. Adjust the height of the metal sheets within the magnetized semiconductor. To determine its total height Obtain the desired stepped phase distribution.

[0064] Step 7: Generate the Airy beam. The effect of the Airy beam generated based on this embodiment is shown in Figure 6(a).

[0065] Table 1

[0066]

[0067] Table 2

[0068]

[0069] This invention supports unidirectional terahertz transmission based on magnetic surface plasmons. It not only achieves phase modulation by adjusting the height of the metal sheet but also achieves continuous amplitude modulation by continuously modulating the thickness of the radiating layer using a continuous function model. Compared to metasurfaces that rely on discrete structures, this invention reduces energy loss and wavefront distortion, improving beam modulation accuracy and stability. Based on these characteristics, this invention designs and generates a one-dimensional finite Airy beam with self-acceleration, diffraction-free, and self-healing properties, expanding the application prospects of magnetic surface plasmons in the field of terahertz controllable optical field modulation.

[0070] Example 3

[0071] This embodiment, based on Embodiment 1 of the present invention, adds a circular obstacle with a radius r=50 in the propagation path of the Airy beam. In this embodiment, the Airy beam generated based on Embodiment 1 of the present invention has self-healing properties, and its verification effect is shown in Figure 6(b). The Airy beam is reconstructed after passing through the obstacle and restores its original distribution characteristics, which fully proves that it has significant self-healing properties.

[0072] Example 4

[0073] The unidirectional magnetic surface plasmonic waveguide in Embodiment 1 of this invention is immune to backscattering caused by defects (or bending). In this embodiment, a circular obstacle with a radius r = 5 is added to the waveguide of Embodiment 1. The transmission effect is shown in Figure 2(c). The electromagnetic wave bypassed the obstacle and did not produce backscattering, which proves that the waveguide structure is immune to scattering caused by defects. This is due to its non-reciprocal unidirectional transmission characteristics.

[0074] The embodiments described are merely preferred embodiments of the present invention and are more general in nature. They are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A terahertz continuous metasurface device based on magnetic surface plasmons for generating a one-dimensional finite Airy beam with self-acceleration, diffraction-free, and self-healing properties, characterized in that: An electrically opaque layer, a dielectric layer, and a magnetized semiconductor layer, extending along the direction of unidirectional waveguide propagation, are horizontally stacked sequentially from top to bottom to form the substrate of the unidirectional waveguide. The direction of unidirectional waveguide propagation is defined as the X direction, the direction perpendicular to the X direction on the horizontal plane is defined as the Y direction, and the direction perpendicular to the horizontal plane is defined as the Z direction. The electrically opaque layer, dielectric layer, and magnetized semiconductor layer are uniform in the Y direction. The magnetized semiconductor is a gyroelectric material. Under the action of a static magnetic field, its relative permittivity is converted into a tensor form, which endows the waveguide with non-reciprocal properties, thereby supporting terahertz unidirectional transmission based on magnetic surface plasma. The electrically opaque layer serves as a radiation layer. Its bottom surface is flat, and its upper surface exhibits a continuous function model along the X direction. Its thickness is modulated by the continuous function model. The continuous function model is based on the functional relationship between the radiation layer thickness and radiation loss. The radiation layer thickness distribution is determined by combining the target energy distribution characteristics of a one-dimensional finite Airy beam. Then, the continuous thickness modulation function of the radiation layer is obtained by fitting, thereby realizing the continuous control of the amplitude of the radiated electromagnetic wave. It also includes a metal sheet array composed of several metal sheets perpendicular to the X direction aligned with each other. The metal sheets pass through the electrically opaque layer and the dielectric layer sequentially from the baseline to the magnetized semiconductor layer. The X-direction position of the metal sheets corresponds to the zero point of the target energy distribution function. The total height of the metal sheets is adapted to the phase modulation of the waveguide mode. The upper surface of the electrically opaque layer is the radiating surface.

2. The terahertz continuous metasurface device based on magnetic surface plasmons according to claim 1, characterized in that, The magnetized semiconductor in a static magnetic field Under its influence, the relative permittivity is transformed into a tensor form, endowing the unidirectional waveguide with non-reciprocal properties, thereby supporting terahertz unidirectional transmission based on magnetic surface plasmons. The relative permittivity tensor has the following form. ,in , , ;in The plasma angular frequency of the magnetized semiconductor. The electron cyclotron frequency is determined by the applied static magnetic field. Decide, The relative permittivity of the magnetized semiconductor at high frequencies, and the plasma frequency of the magnetized semiconductor. .

3. A terahertz continuous metasurface device based on magnetic surface plasmons according to claim 1, characterized in that, The dispersion curve of the unidirectional waveguide completely spans the optical cone, supporting the wave vector. k =0, possessing continuous lateral radiation characteristics, the energy of the supported waveguide modes is radiated into free space through the electrically opaque layer.

4. A terahertz continuous metasurface device based on magnetic surface plasmons according to claim 1, characterized in that, The functional relationship between the thickness of the radiation layer and the radiation loss is as follows: ,in For radiation loss, d The thickness of the radiating layer is denoted by A and B, which are parameters determined by the structural characteristics of the magnetized semiconductor, dielectric, and radiating layer.

5. A terahertz continuous metasurface device based on magnetic surface plasmons according to claim 4, characterized in that, The fitting process yields a continuous thickness modulation function for the radiation layer, which is obtained using polynomial fitting and takes the following form: .

6. A terahertz continuous metasurface device based on magnetic surface plasmons according to claim 1, characterized in that, The target energy distribution of the one-dimensional finite Airy beam has the following form: ,in It is the attenuation factor. The scaling factor in the X direction. , c It is the speed of light.

7. A terahertz continuous metasurface device based on magnetic surface plasmons according to claim 1, characterized in that, The total height of the metal sheet , It is the reference thickness of the radiation layer. For the thickness of the dielectric layer, The height of the metal sheet in the magnetized semiconductor is such that the baseline and the upper surface of the radiating layer are at the same horizontal height when the radiating layer has the reference thickness. The reference thickness of the radiation layer Defined as: when radiation loss The thickness of the radiation layer when it approaches zero; The total height of the metal sheet is adapted to the phase modulation of the waveguide mode by adjusting the metal sheet. To determine its total height This enables phase modulation of the waveguide mode, obtaining the desired stepped phase distribution, and replacing traditional phase modulators.

8. An Airy beam generation method, using a terahertz continuous metasurface device based on magnetic surface plasmons as described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Construct a unidirectional magnetic surface plasmonic waveguide with continuous lateral radiation characteristics; Step 2: Establish the thickness of the radiation layer With radiation loss The functional relationship; Step 3: Determine the target energy distribution function of the one-dimensional Airy beam in the lateral radiation region. ; Step 4: Optimize the radiation energy distribution using an iterative algorithm to make the radiation energy distribution approximate the target energy distribution, thereby obtaining the radiation energy distribution function. ; Step 5: Based on the radiation energy distribution function and the relationship between radiation layer height and radiation loss, obtain the continuous thickness modulation function of the radiation layer. This allows for continuous modulation of the amplitude; Step 6: Introduce a metal sheet array in the waveguide, with its position corresponding to the zero point of the target energy distribution function, to obtain the required stepped phase distribution; Step 7: Generate Airy beam.

9. The method according to claim 8, characterized in that, The radiation energy distribution function described in step four With the target energy distribution function A specific relationship needs to be satisfied, defined as: ,in It is a global attenuation factor used to control the total radiated energy of a unidirectional waveguide.

10. The method according to claim 8, characterized in that, The iterative algorithm described in step four employs an error feedback method, updating the radiation energy distribution based on the difference between the actual radiation energy distribution and the target energy distribution until a predetermined error threshold is reached. The iterative formula is as follows: ,in For the iterative learning rate, To prevent small constants from being divided by zero, This represents the distribution of radiant energy.

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