A device for the regulation of electromagnetic waves

Abstract

The application relates to a kind of electromagnetic wave regulating device, belong to the technical field of electromagnetic wave.The regulating device includes several racemic arrays;Racemic array includes a left-handed array and a right-handed array;Left-handed array includes two left-handed metal spirals, and right-handed array includes two right-handed metal spirals, four metal spirals are arranged into square matrix, and adjacent metal spirals are opposite in chirality;Four metal spirals are the same except chirality in remaining structure.The application can regulate any one or more of polarization, amplitude and phase of electromagnetic wave by rotating metal spiral in racemic array, and can be quantitatively regulated according to specific analytical description.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic wave technology, and in particular to an electromagnetic wave control device. Background Technology

[0002] Electromagnetic waves have wide applications in many fields such as communication and imaging. With the development of science and technology, the flexible and efficient control of the amplitude, phase, and polarization of electromagnetic waves has always been an important research direction. In the field of optics, geometric phase refers to the additional phase increment that light gains in its final state compared to its initial state after evolving along a closed loop on a Poincaré sphere. This is called the Phachanathan-Berry (PB) phase, and its magnitude is equal to half the solid angle corresponding to the loop area. Phase control can be easily achieved by rotating optical elements. Based on the principle of PB phase, devices such as plane lenses, vortex beams, and holographic imaging have been constructed.

[0003] Existing techniques for controlling the polarization, amplitude, and phase of electromagnetic waves using the PB phase principle have two main drawbacks: First, they lack flexibility in electromagnetic wave control. Second, they have strict polarization requirements. Regarding the first drawback—the lack of flexibility in electromagnetic wave control—current unit structures using the PB phase primarily focus on phase control. By rotating the unit structure, phase control of transmitted or reflected electromagnetic waves can be achieved, but amplitude and polarization control cannot be realized. This imposes many limitations in practical applications. For example, tasks requiring simultaneous amplitude and phase control, such as generating Airy beams, cannot be achieved using only PB phase control unit structures, and effective polarization control is also impossible, thus failing to meet the needs of communication applications such as polarization multiplexing. For unit structures capable of simultaneous amplitude and phase control, most methods combine PB phase elements to transmit or detour the phase. By constructing a complex array and altering the structural dimensions or rotation angle, amplitude and phase control of electromagnetic waves are achieved. However, the electric field coupling and control methods of such complex structures are quite complex, preventing arbitrary control of electromagnetic wave amplitude and phase with analytical rules. Furthermore, the computational burden due to structural parameter searches during design is substantial, hindering its widespread application in complex scenarios. Moreover, current PB phase elements offer limited flexibility in electromagnetic wave control, lacking the ability to achieve full-degree-of-freedom control of electromagnetic wave amplitude, phase, and polarization using a single structure. Regarding the second drawback: Current unit structures for electromagnetic wave manipulation using the PB phase method are mainly designed for circularly polarized electromagnetic waves. The PB phase pattern manifests in the polarization states of cross-circularly polarized transmitted electromagnetic waves or co-circularly polarized reflected electromagnetic waves. However, despin arrays can manipulate electromagnetic waves by changing the rotation angles of the two chiral helical structures, thereby controlling the polarization evolution paths of the two elliptical eigenstates. This allows for the manipulation of the polarization, amplitude, and phase of linearly polarized electromagnetic waves using a PB phase-based design, which is beyond the capabilities of existing technologies. Therefore, effectively addressing these issues has become a pressing problem for the industry. Summary of the Invention

[0004] Based on the above analysis, the present invention aims to provide an electromagnetic wave control device to solve the problems of low flexibility in existing electromagnetic wave control and strong polarization requirements.

[0005] On one hand, embodiments of the present invention provide an electromagnetic wave modulation device, comprising:

[0006] The control device includes several despin arrays;

[0007] The despin array includes a left-handed array and a right-handed array;

[0008] The left-handed array includes two left-handed metal spirals, the right-handed array includes two right-handed metal spirals, and the four metal spirals are arranged in a square array with adjacent metal spirals having opposite chirality; the four metal spirals are identical in structure except for chirality.

[0009] Further improvements to the aforementioned control device also include:

[0010] The metal spiral has n spiral cycles in the axial direction, where the value of n is at least 2.

[0011] Based on further improvements to the aforementioned control device, when an electromagnetic wave is incident on the control device, the phase, polarization, and amplitude of the reflected electromagnetic wave can be adjusted by rotating the de-rotation array.

[0012] Based on further improvements to the aforementioned control device, both the left-handed and right-handed arrays in the despin array reflect electromagnetic waves with the same chirality as their array chirality, and transmit electromagnetic waves with the opposite chirality to their array chirality; the eigenstates of the reflected electromagnetic waves of the despin array are two elliptic polarization states, and the polarization tilt angle and ellipticity of the elliptic polarization states can be controlled by rotating the despin array.

[0013] The beneficial effects of the above-mentioned further improvement scheme are: both the despin array and electromagnetic waves have chirality. When their chirality is the same, electromagnetic waves will be reflected; when their chirality is opposite, electromagnetic waves will be transmitted.

[0014] Based on further improvements to the aforementioned control device, the spatial orientation angle and / or phase delay of the fast and slow axes of the despin array can be adjusted by rotating the left-handed and right-handed metal spirals in the despin array.

[0015] The beneficial effects of the above-mentioned further improvement scheme are: the despin array is equivalent to a birefringent element with adjustable fast and slow axes, and rotating the left-handed and right-handed metal spirals in the despin array is equivalent to changing the spatial orientation angle and phase delay of the fast and slow axes corresponding to the linear birefringent element.

[0016] Based on further improvements to the aforementioned control device, the spatial orientation angles and / or phase delays of the fast and slow axes of the despin array are adjusted through the following steps, where the spatial orientation angles of the fast and slow axes are determined by β, and the phase delays are determined by α:

[0017] α=(θ R -θ L ) / 2

[0018] β=(θ R +θ L ) / 2

[0019] In the above formula, the symbol θ RThe symbol θ represents the rotation angle of a right-handed metal helix. L This indicates the rotation angle of a left-handed metal helix.

[0020] The beneficial effects of the above-mentioned further improvement scheme are: it establishes the relationship between the rotation angle of the right-handed metal spiral and the rotation angle of the left-handed metal spiral and the fast axis and slow axis, and the fast axis and slow axis are related to the polarization, amplitude and phase of the reflected electromagnetic wave, thus establishing the relationship between the rotation angle of the right-handed metal spiral and the rotation angle of the left-handed metal spiral and the reflected electromagnetic wave.

[0021] Based on further improvements to the aforementioned control device, one or more of the phase, polarization, and amplitude of the electromagnetic wave can be controlled in the following manner:

[0022] The Jones matrix of the despin array under the online polarization basis vectors can be expressed as:

[0023]

[0024] φ xx = -2arctan[tan(ψ+α)tanχ]

[0025] φ yy = 2arctan[cot(ψ+α)tanχ]

[0026]

[0027] In the above formula, the symbol The Jones matrix representing the despin array, denoted by R(β), represents the rotation matrix, denoted by φ. xx and φ yy The symbol ψ represents the phase of the linear polarization basis vector in the x and y directions, the symbol ψ represents the polarization tilt angle of the intrinsic elliptic state, and the symbol χ represents the ellipticity of the intrinsic elliptic state.

[0028] By adjusting the rotation angles of the left-handed and right-handed metal helices to change the values ​​of α and β, electromagnetic waves with different phases, polarization states, and amplitudes can be obtained through the aforementioned Jones matrix.

[0029] The beneficial effect of the above-mentioned further improvement scheme is that: the incident electromagnetic wave passing through the despin array is equivalent to multiplying the incident electromagnetic wave's matrix by the Jones matrix of the despin array under the linear polarization basis. When determining the desired phase, polarization, and amplitude of the reflected electromagnetic wave, the desired phase, polarization, and amplitude can be substituted into the Jones matrix to derive the symbols α and β, and then obtain the symbol θ. R The rotation angle and sign θ of a right-handed metal helix L The rotation angle of a left-handed metal helix.

[0030] Based on further improvements to the aforementioned control device, within any despin array of a control device, when any left-handed metal spiral is rotated, the remaining left-handed metal spirals in the array rotate synchronously; when any right-handed metal spiral is rotated, the remaining right-handed metal spirals in the array rotate synchronously.

[0031] The beneficial effect of the above-mentioned further improvement scheme is that, regardless of how many despin arrays are in the control device, the metal spirals with the same chirality in the control device rotate synchronously, thereby obtaining consistent reflected electromagnetic waves.

[0032] Based on further improvements to the aforementioned control device, by changing the structural parameters of the metal spiral in the despin array, the frequency band of the electromagnetic wave adapted to the despin array can be changed accordingly.

[0033] The beneficial effects of the above-mentioned further improvement scheme are: by changing the helical radius, diameter, pitch of the metal helix in the despin array and the lattice constant of the despin array, it can be applied to other bands such as terahertz band, infrared band and optical band.

[0034] On the other hand, the present invention also provides a vortex beam generator, which includes m despin arrays arranged in a square array, wherein no despin array is provided in the central region of the square array; the despin array includes a left-handed array and a right-handed array; the left-handed array includes two left-handed metal spirals, the right-handed array includes two right-handed metal spirals, and the four metal spirals are arranged in a square array, with adjacent metal spirals having opposite chirality; the four metal spirals are identical in structure except for chirality.

[0035] The beneficial effect of the above scheme is that by rotating the metal spiral structure in the despin array of the square array, arbitrary phase control can be achieved, thereby enabling the vortex beam generator using the above despin array to have high control accuracy.

[0036] On the other hand, the present invention also provides a dual-focusing cylindrical lens, the dual-focusing cylindrical lens comprising k derotation arrays arranged in a square array, the derotation array comprising one left-handed array and one right-handed array; the left-handed array comprising two left-handed metal spirals, the right-handed array comprising two right-handed metal spirals, the four metal spirals arranged in a square array, adjacent metal spirals having opposite chirality; the four metal spirals are identical in structure except for chirality; wherein, the value of k satisfies the following condition: capable of depicting the amplitude and phase distribution of the dual-focusing cylindrical lens.

[0037] The beneficial effect of the above scheme is that, based on the theoretically preset amplitude and phase distribution, the specific parameters of α and β of the despin array are calculated, and then the preset amplitude and phase distribution can be accurately achieved by rotating the metal spiral structure in the despin array.

[0038] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0039] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0040] Figure 1(a) is a schematic diagram of the three-dimensional structure of the despin array;

[0041] Figure 1(b) is a schematic diagram of the despin array from the top view.

[0042] Figure 2(a) is a schematic diagram of the three-dimensional structure of the metal spiral;

[0043] Figure 2(b) shows the results of the array circular polarization reflection spectrum;

[0044] Figure 3(a) shows the intrinsic basis loss of reflection spectrum;

[0045] Figure 3(b) shows the polarization tilt angles of the eigenstates of reflected waves from different chiral arrays;

[0046] Figure 3(c) shows the polarization ellipticity of the eigenstates of reflected waves from different chiral subarrays;

[0047] Figure 3(d) shows the reflection phase diagrams of eigenstates of different chiral subarrays;

[0048] Figure 4(a) shows the linearly polarized electromagnetic wave reflection spectrum when the subarray is not rotated;

[0049] Figure 4(b) shows the reflection spectrum of a linearly polarized electromagnetic wave as α changes when β is fixed at 0°.

[0050] Figure 4(c) shows the reflection phase diagram of a linearly polarized electromagnetic wave as a function of α when β is fixed at 0°.

[0051] Figure 4(d) shows the reflection variation of a linearly polarized electromagnetic wave as α changes when β is fixed at 0°.

[0052] Figure 4(e) shows the polarization evolution path of different polarization states represented by the Poincaré sphere;

[0053] Figure 4(f) shows the phase difference of co-polarized reflection of linearly polarized electromagnetic waves as α changes when β is fixed at 0°.

[0054] Figure 5(a) is a schematic diagram of a vortex beam generator array;

[0055] Figure 5(b) shows a physical diagram of the vortex beam generator array;

[0056] Figure 5(c) shows the simulation results of the electric field distribution of the vortex beam;

[0057] Figure 5(d) shows the simulation results of the vortex beam phase distribution;

[0058] Figure 5(e) shows the experimental results of the electric field distribution of the vortex beam;

[0059] Figure 5(f) shows the experimental results of the vortex beam phase distribution;

[0060] Figure 6(a) shows the incident polarization conversion reflection spectrum of x-polarized electromagnetic wave obtained by simulation and experiment when α is 0° and β is 45°;

[0061] Figure 6(b) shows the incident polarization conversion reflection spectrum of y-polarized electromagnetic waves obtained by simulation and experiment when α is 0° and β is 45°;

[0062] Figure 6(c) shows the incident polarization conversion reflection spectrum of x-polarized electromagnetic waves obtained by simulation and experiment when α is 0° and β is 22.5°.

[0063] Figure 6(d) shows the incident polarization conversion reflection spectrum of y-polarized electromagnetic waves obtained from simulation and experiment when α is 0° and β is 22.5°.

[0064] Figure 7(a) shows the incident polarization conversion reflection spectrum of x-polarized electromagnetic wave obtained by simulation and experiment when α is 45° and β is 45°;

[0065] Figure 7(b) shows the incident polarization conversion reflection spectrum of y-polarized electromagnetic waves obtained by simulation and experiment when α is 45° and β is 45°.

[0066] Figure 7(c) shows the theoretical distribution of ψ' as a function of α and β when a right-hand circularly polarized electromagnetic wave is incident.

[0067] Figure 7(d) shows the theoretical distribution of χ' as a function of α and β when a right-hand circularly polarized electromagnetic wave is incident.

[0068] Figure 7(e) shows the reflection spectrum of the right-hand circularly polarized electromagnetic wave incident when α and β are 12° and 15°, respectively, obtained by simulation and experiment.

[0069] Figure 7(f) shows the reflection spectrum of the incident left-hand circularly polarized electromagnetic wave obtained by simulation and experiment when α and β are 12° and 15°, respectively.

[0070] Figure 8(a) shows the reflection spectrum of the electromagnetic wave whose amplitude changes from x-polarized to y-polarized when α is 0° as a function of β.

[0071] Figure 8(b) shows the variation of amplitude and phase of the x-polarized to y-polarized electromagnetic wave with β when α is 0°.

[0072] Figure 8(c) shows the variation of the co-polarization reflection amplitude of the x-polarized electromagnetic wave with α and β, which is obtained from theoretical calculations when ψ = 0° and χ = 22.5°.

[0073] Figure 8(d) shows the variation of the co-polarization reflection phase of the x-polarized electromagnetic wave with α and β, obtained by theoretical calculation when ψ = 0° and χ = 22.5°.

[0074] Figure 9(a) shows the normalized amplitude distribution (realization) and sample sampling point (block) distribution of the dual-focusing cylindrical lens;

[0075] Figure 9(b) shows the normalized phase distribution (realization) and sample sampling point (block) distribution of the dual-focusing cylindrical lens;

[0076] Figure 9(c) shows the electric field distribution at 14.4 GHz obtained from simulation calculations;

[0077] Figure 9(d) shows the electric field distribution at the focal position (dashed line) obtained from the simulation. Detailed Implementation

[0078] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0079] A specific embodiment of the present invention discloses an electromagnetic wave control device, the control device comprising a plurality of despin arrays;

[0080] The despin array includes a left-handed array and a right-handed array;

[0081] The left-handed array includes two left-handed metal spirals, the right-handed array includes two right-handed metal spirals, and the four metal spirals are arranged in a square array with adjacent metal spirals having opposite chirality; the four metal spirals are identical in structure except for chirality.

[0082] As shown in Figure 1(a).

[0083] In practice, for despin arrays containing both chiral structures, the orthogonality of left- and right-hand circularly polarized electromagnetic waves allows for independent PB phase modulation of electromagnetic waves with different chiral polarizations. This can be used for applications such as polarization-tunable holographic imaging. The despin array in this application offers wide-ranging and flexible applications for electromagnetic wave modulation, including terahertz and infrared bands.

[0084] In a despin array, the PB phase associated with the elliptical eigenpolarity state can be used to control the polarization, amplitude, and phase of electromagnetic waves. The two reflected elliptical eigenpolarity states are controlled by metal screws of different chiralities, enabling independent polarization path evolution and PB phase accumulation. This effect is similar to that of a linear birefringent element. The direction and phase delay of the fast and slow axes of the despin array can be controlled by the metal screws of the despin array. This property allows for phase modulation, polarization conversion, and complex amplitude modulation of reflected electromagnetic waves.

[0085] Figures 1(a) and 1(b) illustrate a racemic array structure composed of two sets of metal helices with opposite chirality, arranged diagonally according to their chirality. Except for chirality, the metal helices share the same structural and material properties. In a preferred embodiment, the racemic array has a lattice constant 2d = 20 mm, a helical radius a = 3 mm, a helix diameter δ = 0.6 mm, and a pitch p = 4 mm. Each helical structure has three cycles along its axial direction. The rotation angle of the metal helix is ​​defined as the angle of rotation of the starting point around the axis of the metal helix. The rotation angles of the left-handed and right-handed metal helices are defined as θ. L and θ R The left-handed and right-handed chirality of a metal helix is ​​represented by L and R, respectively.

[0086] As shown in Figure 2(a), the metal spiral in the racemic array can be decomposed into a left-handed array and a right-handed array. The lattice constant of the left-handed array or the right-handed array is... Taking a right-handed helical unit structure as an example, the simulation results are shown in Figure 2(b), where RCP represents right-handed circular polarization, LCP represents left-handed circular polarization, and the subscripts from left to right represent the polarization of the reflected wave and the polarization of the incident wave, respectively. The metal helix can only transmit electromagnetic waves with opposite chirality (i.e., left-handed circularly polarized electromagnetic waves), while electromagnetic waves with the same chirality as the metal helix (i.e., right-handed circularly polarized electromagnetic waves) are reflected. From the array circularly polarized reflection spectrum in Figure 2(b), it can be concluded that a certain amount of right-handed circularly polarized electromagnetic waves are converted into left-handed circularly polarized electromagnetic waves. This is due to the symmetry breaking caused by the finite length of the metal helix. It can also be understood that for this finite-length metal helix structure, the intrinsic polarization of its reflected waves is not two purely circularly polarized states.

[0087] Compared with the prior art, the despin array in the electromagnetic wave control device provided in this embodiment has a wide range of control capabilities and a simple control method, which has a great advantage over the current pure phase control of circularly polarized electromagnetic waves.

[0088] Analysis revealed that the intrinsic polarization of the reflected wave from a finite-length metal spiral is a pair of orthogonal elliptic polarization states. These two elliptic polarization states, defined as A and B, can be represented on a Poincaré sphere as (2ψ) R ,2χ R ) and (2(ψ) R +90°), -2χ R Taking a right-handed metallic helix as an example, the reflection spectrum lost by the eigenstate at a rotation angle of 0° is shown in Figure 3(a). Analysis of the transmission spectrum of the eigenstates of the right-handed metallic helix subarray reveals that at 14.4 GHz, for the right-handed elliptic state A, almost all is reflected and the polarization state remains unchanged, while for the elliptic state B, it is completely transmitted without reflection. The polarization tilt angle ψ of its elliptic polarization state is calculated. R and ellipticity χ R Each as Figure 3(b) and 3(c) As shown in the block diagram, the analysis results, taking a right-handed metallic helical subarray as an example, show that for a left-handed metallic helical subarray, due to the mirror symmetry of its structure with the right-handed array, its reflection spectrum under the elliptical eigenstate polarization basis vectors is mirror symmetric with that of the right-handed subarray. The eigenstate of the left-handed metallic helical subarray is defined as A when the structural rotation angle is 0°. * (2ψ L ,2χ L ) and B * (2(ψ L +90), -2χ L Its polarization tilt angle ψ L and χ L As shown by the dots in Figures 3(b) and (c), the values ​​of states A and (c) are equal in magnitude but opposite in sign, proving that the two states are mirror-symmetric along the xoz plane. State A can be seen in Figure 3(d). * The reflection phase is the same as that of state A, which also proves the mirror symmetry relationship between the two states. The eigenstates are uniquely related to the principal symmetry of the helical structure; therefore, when the metal helical structure rotates, the polarization tilt angle of the eigenstates will change by the same value. For example, if the metal helical structure in a right-handed subarray rotates by θ°, the coordinates of its eigenstates on the Poincaré sphere will change accordingly to (2(ψ)). R +θ),2χ R ) and (2(ψ) R +θ+90°),-2χ R The ellipticity and reflection spectrum remain unchanged under the new eigenvalues.

[0089] Two arrays with different chiralities reflect electromagnetic waves in elliptical polarization states that share the same chirality. A derotating array, possessing both chiralities, can achieve total internal reflection of both elliptical polarization states simultaneously. The rotation angles of the left-handed and right-handed metal helices in the derotating array are defined as θ. L and θ R The coordinates of the two elliptic states on the Poincaré sphere are respectively represented as E R (2(ψ+θ R ),2χ) and E R (-2(ψ-θ L ),-2χ).

[0090] In one embodiment, the metal spiral has n spiral cycles in the axial direction, where n is at least 2. In one embodiment, three spiral cycles are used as an example, and the processing of the remaining spiral cycles is the same as that of three spiral cycles.

[0091] In one embodiment, when an electromagnetic wave is incident on the control device, the polarization, amplitude, and phase of the reflected electromagnetic wave are adjusted by rotating the despin array. Both the left-hand and right-hand spiral arrays in the despin array reflect electromagnetic waves with the same chirality as their array chirality and transmit electromagnetic waves with the opposite chirality. The eigenstates of the reflected electromagnetic wave from the despin array are two elliptical polarization states, and the azimuth and ellipticity of these elliptical polarization states are adjusted by rotating the despin array. The spatial orientation angle and / or phase delay of the fast and slow axes of the despin array are adjusted by rotating the left-hand and right-hand spiral metal helices in the despin array.

[0092] In practice, within any derotation array of a control device, when any left-handed metal spiral is rotated, the remaining left-handed metal spirals in the array rotate synchronously; when any right-handed metal spiral is rotated, the remaining right-handed metal spirals in the array rotate synchronously.

[0093] Specifically, the spatial orientation angles and / or phase delays of the fast and slow axes of the despin array are adjusted through the following steps, where the directions of the fast and slow axes are determined by β, and the phase delay is determined by α:

[0094] α=(θ R -θ L ) / 2

[0095] β=(θ R +θ L ) / 2

[0096] The spatial orientation angle in the above formula is denoted by θ. R The symbol θ represents the rotation angle of a right-handed metal helix. L This indicates the rotation angle of a left-handed metal helix.

[0097] Specifically, the phase, polarization, and complex amplitude of electromagnetic waves are controlled in the following ways:

[0098] The Jones matrix of the despin array under the online polarization basis vectors can be expressed as:

[0099]

[0100] φ xx =-2arctan[tan(ψ+α)tanχ] (2)

[0101] φ yy =2arctan[cot(ψ+α)tanχ] (3)

[0102]

[0103] In the above formula, the symbol The Jones matrix representing the despin array, denoted by R(β), represents the rotation matrix, denoted by φ. xx and φ yy The symbol ψ represents the phase of the linear polarization basis vector in the x and y directions, the symbol ψ represents the polarization tilt angle of the intrinsic elliptic state, and the symbol χ represents the ellipticity of the intrinsic elliptic state.

[0104] By adjusting the rotation angles of the left-handed and right-handed metal helices to change the values ​​of α and β, electromagnetic waves with different phases, polarization states, and amplitudes can be obtained through the aforementioned Jones matrix.

[0105] From formula (1), it can be deduced that the reflection characteristics of the despin array are similar to those of a linear birefringent element, and the directions and phases of its fast and slow axes can be achieved by rotating a metal spiral. Specifically, the directions of the fast and slow axes are determined by β, and the phase delay is determined by α. When the range of α is from -90° to 90°, according to formulas (2) and (3), the reflection phase φ xx and φ yy The phase difference between the fast and slow axes can be continuously adjusted from 0° to 360°, meaning the phase difference can be controlled by α. In particular, when ψ+α equals 0, the phase difference between the fast and slow axes can always be 180°, and this characteristic can be used to achieve polarization control.

[0106] The following verification is demonstrated by showing the reflection spectrum of the despin array. As shown in Figure 4(a), when the left and right helical metal spiral structures in the despin array are not rotating, the despin array reflects x- and y-polarized incident electromagnetic waves in the same polarization at 14.4 GHz, and no repolarization component is generated. When β is fixed at 0°, during the rotation of α from -90° to 90°, the amplitude of the same polarization reflection of x- and y-polarized incident electromagnetic waves remains at 1, and the cross-polarization is 0, as shown in Figure 4(b). The reflection phase φ xx and φ yy There is a 360° range of variation, as shown in Figure 4(c). To more clearly represent the phase change, the phase variation with α is represented by the phase difference in Figure 4(d), with x-polarized incident and α and β as 0° phase values ​​as reference values. According to formulas (2) and (3), for the two ellipticized reflection states at 14.4 GHz, the polarization tilt angle ψ≈0° and ellipticity χ≈22.5° are calculated. These two elliptic states are related to the A and A of the left and right spinner arrays. * The states differ slightly, mainly due to the coupling between structures formed by subarrays of different chirality after despinning. At ψ = 0° and χ = 22.5°, φ... xx and φ yy The reflection phase is shown by solid and dashed lines in Figure 4(d), and its variation relationship matches the simulation calculation very well. Considering that β is 0° in this case, i.e., θ... L and θ R If the magnitudes are equal and the signs are opposite, then these two elliptic reflection states at 14.4 GHz can be represented as E R (2α,2χ) and E L (-2α, -2χ), and for the incident polarization state, since its propagation direction is opposite to that of the reflected elliptic polarization state, its polarization state is represented in the incident coordinate system as (-2α, -2χ). and For example, an incident x-polarized electromagnetic wave can be represented as having the same amplitude and phase. and The polarization evolution paths of the two elliptic polarization states of the incident electromagnetic wave with the x-polarization are as follows: and The path evolution accumulates a geometric phase, which manifests as the phase change of the x-polarized electromagnetic wave with respect to α. Due to their different polarization evolution paths, the phase changes of x-polarized and y-polarized incident electromagnetic waves with respect to α are different, as shown in Figure 4(e). Figure 4(f) illustrates the phase difference between x-polarized and y-polarized co-polarized reflections, Δφ = φ yy -φ xxThis can cover the range of [-180°, -90°] and [90°, -180°), meaning that the polarization state of the reflected wave can be continuously controlled for this despin array, not just limited to the performance of half-wave or quarter-wave plates. Furthermore, by changing β, the directions of the fast and slow axes can be altered, allowing the invention to flexibly control the polarization, amplitude, and phase of the reflected electromagnetic wave. The following examples demonstrate the flexible control capability of this invention over electromagnetic waves.

[0107] In one embodiment, phase modulation of reflected electromagnetic waves is achieved using a despin array. The despin array is analogous to a linear birefringent element and allows arbitrary adjustment of the fast and slow axes phase. By rotating the metal spirals, the phase of linearly polarized electromagnetic waves can be arbitrarily controlled. A vortex beam generator was designed using this despin array, as shown in Figures 5(a) and 5(b). The vortex beam generator includes m despin arrays arranged in a square array, with no despin arrays in the central region of the square array. Each despin array includes one left-handed spiral array and one right-handed spiral array. The left-handed spiral array includes two left-handed metal spirals, and the right-handed spiral array includes two right-handed metal spirals. The four metal spirals are arranged in a square array, with adjacent spirals exhibiting opposite chirality. The four metal spirals are identical in structure except for their chirality.

[0108] It should be noted that the central region mentioned above can be the location of the center element of a square array, or the location of multiple elements at the center. For example, when the square array formed by the vortex beam generator is a 3×3 square array, the central region can be the location of the center element. No despin array is set in the central region, so for a 3×3 square array, the vortex beam generator is ultimately composed of 8 despin arrays.

[0109] The central region can also be the location of multiple array elements at the center. For example, when a 5×5 square array vortex beam generator is formed, the position corresponding to the 3×3 square array at the center is the central region. No despin array is set in the central region, and the final vortex beam generator is composed of 16 despin arrays.

[0110] The beam reflected by the vortex beam generator has The spiral phase wavefront in the form of, where Let α be the azimuth angle, which is the angle between the despin array and the positive x-axis, and l be the beam topological charge. As shown in Figure 4(d), the full-range reflection phase modulation of x- and y-polarized electromagnetic waves can be achieved by changing α. Let β be fixed at 0° for each despin array unit structure, and determine α according to formula (2) so that each unit structure satisfies Relationship, The azimuth angle for each unit structure.

[0111] In one embodiment, Figures 5(a) and 5(b) show a schematic diagram and experimental setup of an x-polarized vortex beam generator with a topological charge of 1. This generator requires only 8 despin array units, forming a 3×3 square array, with no design at the center. Simulation and experimental results are shown in Figures 5(c)-(f). Figures 5(c) and 5(e) represent the electric field intensity distribution of the vortex beam obtained from simulation and experiment, respectively, while Figures 5(d) and 5(f) are the phase diagrams obtained from simulation and experiment. The electric field is located at a distance of 100 mm from the structure. The simulation and experimental results of the vortex beam generator are in good agreement. According to formula (1), the despin array can control the direction of the fast and slow axes by changing β, which means that the phase of any linearly polarized electromagnetic wave can be controlled. In addition, when the phase difference between the fast axis and the slow axis is kept at 180°, the control capability of this despin array can be equivalent to a reflective half-wave plate, which can reflect circularly polarized electromagnetic waves without changing the polarization. The phase control of the circularly polarized electromagnetic waves can be achieved by changing the β-controlled geometric phase.

[0112] In one embodiment, polarization control of reflected electromagnetic waves is achieved through a despin array. Since the despin array can adjust the directions of the fast and slow axes, as well as the phase delay of the fast and slow axes, polarization control can be achieved by adjusting the phase difference between the fast and slow axes. Taking the polarization direction control of linearly polarized electromagnetic waves as an example, when α and β are both 0°, the despin array can be analogous to a reflective half-wave plate, because the directions of its fast and slow axes can be rotated by changing β, thus reflecting the incident linearly polarized electromagnetic wave into an arbitrary polarization direction. This can be verified experimentally. The sample consists of a 30×30 despin array as the control device, where α is set to 0°, and β is set to 45° and 22.5° respectively. The experimental and simulation results are shown in Figure 6. When β is 45° and 22.5°, the polarization directions of the x- and y-polarized incident electromagnetic waves are rotated by 90° and 45° respectively. By altering the phase delay between the fast and slow axes, the despin array can introduce additional phase differences of [-180°, -90°] and [90°, -180°] (as shown in Figure 4). This property enables the conversion of linear polarization to circular polarization, equivalent to a reflective quarter-wave plate. With α and β both set to 45°, and x- and y-polarized electromagnetic waves incident, the reflected waves are converted into left-handed and right-handed circularly polarized electromagnetic waves, respectively. Simulation and experimental results are shown in Figures 7(a) and (b).

[0113] In one embodiment, based on the adjustable phase difference and direction of the fast and slow axes, many polarization conversion functions can also be realized. Taking the incident right-hand circularly polarized electromagnetic wave as an example, its reflection Jones matrix can be expressed as formula (4).

[0114]

[0115] From formula (4), it can be concluded that the ellipticity of the polarization state is determined by the phase difference Δφ, which is determined by α in formulas (2) and (3) and the ellipticity. The polarization tilt angle is determined by the parameter β. The theoretical calculation of the relationship between the polarization tilt angle ψ' and ellipticity χ' of the reflected wave polarization state under the incident right-hand circularly polarized electromagnetic wave and α and β is shown in Figures 7(c) and (d). The polarization tilt angle ψ' can be arbitrarily adjusted by β over the entire range, and the ellipticity χ' is adjusted by α within the range of [0°, 45°]. Therefore, by adjusting α and β, the right-hand circularly polarized electromagnetic wave can be reflected into any right-hand elliptic polarization or linear polarization state. The left-hand circularly polarized wave is the opposite and can be reflected into any left-hand elliptic polarization or linear polarization state. Taking parameters α and β as 12° and 15° respectively as examples, right-hand circularly polarized electromagnetic waves will be reflected into polarization states with polarization tilt angles and ellipticity of 60° and 22.865° respectively, denoted as elliptic state γ. Left-hand circularly polarized electromagnetic waves will be reflected into polarization states with polarization tilt angles and ellipticity of 150° and -22.865° respectively, denoted as elliptic state γ'. Simulation and experimental results are shown in Figures 7(e) and (f).

[0116] In one embodiment, the complex amplitude modulation of the reflected electromagnetic wave is achieved through a despin array. When the fast and slow axes of the despin array satisfy a 180° phase difference, the despin array can be equivalent to a reflective half-wave plate, and the Jones matrix of equation (1) can be written as follows:

[0117]

[0118] For electromagnetic waves incident with x and y polarization, the cross-polarization reflection coefficient is sin(2β), which allows for amplitude modulation from 0 to 1 and binary modulation of the phase at 0° or 180°. Figure 8(a) shows the calculated amplitude of the x-polarized electromagnetic wave converted to y-polarized electromagnetic waves as β is 0°, 15°, 30°, and 45°, while Figure 8(b) shows the amplitude and phase changes of the x-polarized electromagnetic wave incident to y-polarized electromagnetic waves as β changes, with α being 0°.

[0119] Besides achieving full-range amplitude control and binary phase control by changing β, the reflection characteristics of the despin array can also be controlled by changing α and β to regulate the complex amplitude. According to formula (1), for the co-polarized reflection of an x-polarized electromagnetic wave, the reflection coefficient can be expressed as:

[0120]

[0121] According to formula (6), by adjusting α and β, the amplitude and phase of the reflection coefficient can be arbitrarily adjusted in the full range. The results of theoretical analysis and simulation calculation when ψ = 0° and χ = 22.5° are shown in Figure 8 (c)-8 (d).

[0122] In one embodiment, the complex amplitude control capability of the proposed despin array is verified by designing a bifocal metasurface. This embodiment provides a bifocal cylindrical lens comprising k despin arrays arranged in a square array. Each despin array includes one left-handed array and one right-handed array. The left-handed array comprises two left-handed metal spirals, and the right-handed array comprises two right-handed metal spirals. The four metal spirals are arranged in a square array, with adjacent spirals exhibiting opposite chirality. The four metal spirals are identical in structure except for chirality. The value of k satisfies the condition that it can depict the amplitude and phase distribution trend of the bifocal cylindrical lens.

[0123] In another specific embodiment, a 31×31 array was constructed based on the amplitude and phase distribution of the dual-focusing cylindrical lens, and the amplitude and phase distribution formula is as follows:

[0124]

[0125] Where f1=f2=540mm, x1=-75mm, x2=75mm, and λ0 is the wavelength of free space at 14.4GHz, the designed amplitude and phase distribution along the x-direction are shown in Figures 9(a) and (b). The solid line is calculated by formula (7), and the square represents discrete sampling points. The number of sampling points is k, and the interval period is 20mm. According to the required amplitude and phase distribution, combined with formula (6), the specific parameters of α and β of the despin array unit at the corresponding position in the x-direction can be obtained. The same parameters are applied to each row in the y-direction. The simulation calculation results are shown in Figure 9(c). According to the electric field distribution diagram, the double-focusing effect is consistent with the theoretical analysis. The theoretical focusing position is represented by a dashed line. The specific electric field value of the dashed line is shown in Figure 9(d). It can be seen that the electric field intensity at the preset focal position is significantly enhanced, and the double-focusing effect is consistent with the theoretical analysis.

[0126] This invention designs a control device comprising a despin array, a vortex beam generator, and a dual-focusing cylindrical lens, demonstrating its ability to control electromagnetic waves based on the PB phase. The despin array reflects electromagnetic waves in elliptical polarized eigenstates, and its control capability can be equivalent to a unit with linear birefringence. By rotating the metal spiral structures of different chirality within the despin array, the azimuth angle and phase difference of the fast and slow axes can be equivalently controlled, thereby achieving control over the amplitude, phase, and polarization of the electromagnetic waves. This invention provides flexible control over electromagnetic waves; simply rotating the metal spirals allows for flexible control over the phase, polarization, and complex amplitude. The technical solution of this application can be used to design complex optical field control devices with broad control capabilities and excellent control effects. By changing the dimensions of the metal spirals in the despin array, it can also be applied to other frequency bands.

[0127] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.

[0128] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in one or more blocks of the flowchart illustrations and / or one or more blocks of the block diagrams.

[0129] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means that implement the functions specified in one or more flowcharts and / or one or more block diagrams.

[0130] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, such that the instructions, which execute on the computer or other programmable apparatus, provide steps for implementing the functions specified in one or more flowcharts and / or one or more block diagrams.

[0131] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A device for controlling electromagnetic waves, characterized in that, include: The control device includes several despin arrays; The despin array includes a left-handed array and a right-handed array; The left-handed array includes two left-handed metal spirals, and the right-handed array includes two right-handed metal spirals. The two left-handed metal spirals and the two right-handed metal spirals are arranged in a square array, and adjacent metal spirals have opposite chirality. The four metal spirals are identical in structure except for chirality. When an electromagnetic wave is incident on the control device, the phase, polarization, and amplitude of the reflected electromagnetic wave can be adjusted by rotating the derotation array. The spatial orientation angle and / or phase delay of the fast and slow axes of the despin array are adjusted by rotating the left-handed and right-handed metal spirals in the despin array. The spatial orientation angles and / or phase delays of the fast and slow axes of the despin array are adjusted as follows: the spatial orientation angles of the fast and slow axes are determined by... The phase delay is determined by Decide: ； ； The symbols in the above formula The symbol represents the rotation angle of a right-handed metal helix. Indicates the rotation angle of a left-handed metal helix; The phase, polarization, and amplitude of an electromagnetic wave can be modulated by the following steps: The Jones matrix of the despin array under the online polarization basis is expressed as: ； ； ； ； In the above formula, the symbol The Jones matrix representing a despin array, symbol Represents a rotation matrix, symbol and The phase of the linearly polarized basis vector in the x and y directions is represented by the symbol. The polarization tilt angle of the intrinsic elliptic state is represented by the symbol. The ellipticity of the intrinsic ellipticity; By adjusting the rotation angle of the left-handed and right-handed metal spirals, the... and The value is then used to obtain electromagnetic waves with different phases, polarization states, and amplitudes through the aforementioned Jones matrix.

2. The electromagnetic wave control device according to claim 1, characterized in that, Also includes: The metal spiral has n spiral cycles in the axial direction, where the value of n is at least 2.

3. The electromagnetic wave control device according to claim 1, characterized in that, Both the left-handed and right-handed arrays in the despin array reflect electromagnetic waves with the same chirality as the array chirality, and transmit electromagnetic waves with the opposite chirality to the array chirality. The eigenstates of the reflected electromagnetic waves from the despin array are two elliptic polarization states, and the polarization tilt and ellipticity of the elliptic polarization states can be controlled by rotating the despin array.

4. The electromagnetic wave control device according to claim 1, characterized in that, Within any de-rotation array of a control device, when any left-handed metal spiral is rotated, the remaining left-handed metal spirals in the array rotate synchronously; when any right-handed metal spiral is rotated, the remaining right-handed metal spirals in the array rotate synchronously.

5. The electromagnetic wave control device according to claim 1, characterized in that, Also includes: By changing the structural parameters of the metal spirals in the despin array, the frequency band of the electromagnetic waves adapted to the despin array can be changed accordingly.

6. A vortex beam generator, characterized in that, The vortex beam generator includes m despin arrays arranged in a square array, with no despin arrays in the central region of the square array; each despin array includes one left-handed array and one right-handed array; the left-handed array includes two left-handed metal spirals, and the right-handed array includes two right-handed metal spirals, which are arranged in a square array with adjacent spirals having opposite chirality; the four metal spirals are identical in structure except for their chirality.

7. A bifocal lens, characterized in that, The dual-focusing cylindrical lens comprises k derotation arrays arranged in a square array. Each derotation array includes one left-handed array and one right-handed array. The left-handed array includes two left-handed metal spirals, and the right-handed array includes two right-handed metal spirals. The two left-handed and two right-handed metal spirals are arranged in a square array, with adjacent metal spirals exhibiting opposite chirality. The four metal spirals are identical in structure except for their chirality. The value of k satisfies the following condition: it can depict the amplitude and phase distribution trend of the dual-focusing cylindrical lens.

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