High-Q-value polarization-regulated planar dielectric metamaterial

Abstract

The invention relates to the technical field of metamaterials, in particular to a high-Q-value polarization regulation plane medium metamaterial. The embodiment of the invention provides a high-Q-value polarization-regulated planar dielectric metamaterial, which comprises a plurality of cylinders, the plurality of cylinders are arranged along two orthogonal directions in a plane to form an array structure formed by the plurality of cylinders, the plurality of cylinders comprise a plurality of first cylinders and a plurality of second cylinders, the diameters of the first cylinders and the diameters of the second cylinders are different, and the first cylinders and the second cylinders are different from each other. The column bodies are the same in type and are first column bodies or second column bodies in one direction of the orthogonal arrangement, and the first column bodies and the second column bodies are alternately arranged in the other direction of the orthogonal arrangement. The embodiment of the invention provides a high-Q-value polarization regulation plane medium metamaterial which can regulate the intrinsic polarization state in the neighborhood of an infinite high-Q-value BIC on the premise that the BIC stably exists.

Description

Technical Field

[0001] This invention relates to the field of metamaterials technology, and in particular to a planar dielectric metamaterial with high Q-value polarization modulation. Background Technology

[0002] Bound states (BICs) in the optical continuum are a special type of optical nonradiative mode that can ideally trap light, perfectly localizing it even when its frequencies lie within the radiative continuum. Theoretically, they possess an infinitely high Q-factor. Metamaterials with periodic structures are the primary platform for realizing and observing BICs. Furthermore, BICs possess certain topological properties, which allow manipulation of the intrinsic polarization state distribution of the structure by adjusting parameters such as the size and material composition of the metamaterial structural units. These intrinsic polarization states can be considered as excitable quasi-BICs originating from BICs, exhibiting extremely high Q-factors and strong localized fields, making them promising for applications in high-Q polarization manipulation, sensors, and lasers.

[0003] Typically, a symmetry-protected circularly polarized state (BIC) can be easily achieved when a periodic structure maintains mirror or in-plane inversion symmetry. However, the general method for modulating intrinsic polarization states requires breaking the mirror or in-plane inversion symmetry of the structure. This symmetry breaking leads to the disappearance of the symmetry-protected BIC, which in turn limits the Q-value of the modulated polarization state, making it insufficient to meet the performance requirements of high-power sensors, lasers, and other optical devices. In particular, the modulation of intrinsic circularly polarized states has broad application prospects in high-Q chiral excitation and chiral recognition.

[0004] Therefore, to address the above shortcomings, it is necessary to provide a structure that can achieve high-Q intrinsic polarization control to solve these deficiencies. Summary of the Invention

[0005] This invention provides a planar dielectric metamaterial with high Q-value polarization control, which can control the intrinsic polarization state in the neighborhood of an infinitely high Q-value BIC while ensuring the stable existence of BIC.

[0006] This invention provides a planar dielectric metamaterial with high Q-value polarization control, comprising multiple pillars arranged in two orthogonal directions within a plane to form an array structure. The multiple pillars include multiple first pillars and multiple second pillars, the first pillars and the second pillars having different diameters. Along one orthogonal direction, the pillars are of the same type, either first pillars or second pillars. Along the other orthogonal direction, the first pillars and the second pillars are alternately arranged.

[0007] In one possible design, the midpoints of the axial segments of all the columns lie in the same plane, making the metamaterial symmetrical about this plane along its thickness direction.

[0008] In one possible design, the metamaterial is designed by adjusting the polarization direction by adjusting the thickness of the column.

[0009] In one possible design, the column is made of silicon.

[0010] In one possible design, the silicon has a refractive index of 3.5.

[0011] In one possible design, the distance between the centers of the columns is equal along two orthogonal directions.

[0012] In one possible design, the radius of the first column... The radius of the second column ,in, a The distance between the centers of the cylinders is along two orthogonal directions.

[0013] In one possible design, a The wavelength range is 300~700nm.

[0014] Compared with the prior art, the present invention has at least the following beneficial effects: The metamaterial structure provided in this application, while maintaining the in-plane inversion symmetry (the structure remains unchanged after rotating 180° in the plane) and mirror symmetry (mirror symmetry with the center of all cylinders as the plane of symmetry), allows the BIC (Body Integral Capacitor) supported by the structure to remain stable by adjusting the thickness parameters. Furthermore, the polarization state in the neighborhood of the BIC can be tunably controlled to cover linearly polarized states to circularly polarized states, and the Q value of the obtained circularly polarized state can theoretically reach as high as 10. 5 This has significant application value in enhancing photomatter interaction, chiral response, and improving the performance of optical devices. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the metamaterial structure designed in this invention; Figure 2 This invention relates to the distribution of intrinsic polarization states corresponding to the adjusted structural thickness parameters. The positions of the numbers +1 and -1 indicate the presence of BIC, with a topological charge number of +1 or -1. The positions of the yellow and blue dots indicate the presence of right-handed and left-handed circular polarization states, respectively.

[0017] Figure 3 It involves adjusting the structural thickness parameters to determine the Q-value distribution of the circularly polarized state. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] In the description of the embodiments of the present invention, unless otherwise expressly specified and limited, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; unless otherwise specified or stated, the term "multiple" refers to two or more; the terms "connected," "fixed," etc., should be interpreted broadly. For example, "connected" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0020] In this specification, it should be understood that the directional terms such as "upper" and "lower" used in the description of the embodiments of the present invention are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of the present invention. Furthermore, in the context, it should also be understood that when it is mentioned that one element is connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected to the other element "upper" or "lower" through an intermediate element.

[0021] like Figure 1 As shown, this embodiment of the invention provides a planar dielectric metamaterial with high Q-value polarization control, comprising multiple pillars arranged in two orthogonal directions in a plane to form an array structure. The multiple pillars include multiple first pillars and multiple second pillars, the diameters of the first pillars and the second pillars being different. In one orthogonal direction, the pillars are of the same type, either first pillars or second pillars. In the other orthogonal direction, the first pillars and the second pillars are alternately arranged.

[0022] The metamaterial structure provided in this application, while maintaining the in-plane inversion symmetry (the structure remains unchanged after rotating 180° in the plane) and mirror symmetry (mirror symmetry with the center of all cylinders as the plane of symmetry), allows the BIC (Body Integral Capacitor) supported by the structure to remain stable by adjusting the thickness parameters. Furthermore, the polarization state in the neighborhood of the BIC can be tunably controlled to cover linearly polarized states to circularly polarized states, and the Q value of the obtained circularly polarized state can theoretically reach as high as 10. 5 This has significant application value in enhancing photomatter interaction, chiral response, and improving the performance of optical devices.

[0023] In some embodiments of the invention, the midpoints of the axial segments of all the columns are located in the same plane, such that the metamaterial is symmetrical about this plane along the thickness direction.

[0024] In some embodiments of the present invention, the design method of the metamaterial is to adjust the polarization direction by adjusting the thickness of the column.

[0025] When adjusting polarization, the thickness of all pillars is adjusted synchronously so that the thickness of all pillars is equal before and after adjustment.

[0026] The verification process for adjusting polarization by adjusting only the thickness is as follows: Once the dimensions, material parameters, and element arrangement of each component within a structural unit are determined, the intrinsic polarization state of the structure can be controlled by adjusting the thickness parameters. For example, in... and The direction is periodic. Limited thickness in direction and with mirror surface For a symmetric planar structure, when considering a non-degenerate energy band, time-coupled mode theory can be used to describe the in-plane wave vector. resonance Dynamics: in, It is the complex amplitude of resonance. It is the resonant frequency. It is the radiation attenuation rate caused by resonance. and The superscripts represent the complex amplitudes of the incident and emitted waves, respectively. and Subscripts represent the top and bottom of the planar structure, respectively. and They are respectively polarization and Polarization. And , This is the scattering matrix. Here, we assume there is no gain or loss in the system, and consider the modes corresponding to frequencies below the first diffraction order. and It includes the coupling coefficients from the resonance to the four input and output channels: , .matrix It is the direct scattering matrix, which is approximately the scattering matrix of a uniform dielectric plate: here, and These are the transmission coefficient and reflection coefficient of the planar structure, respectively.

[0027] Because this structure has a mirror surface Symmetry, for a thickness of For a single-layer structure, only the eigenmodes radiating upwards need to be analyzed. In this case, the incident wave in the upper half-space is zero ( When the thickness of the structure increases to At that time, relative to the original thickness The incident field in the lower half-space is equivalent to the reflected wave from the bottom of the thickened structure after the downward radiation is reflected. Therefore, the following expression can be obtained: Here, This is due to radiation increasing the thickness. The additional phase generated by internal round-trip propagation. Furthermore, the structure... Symmetry requires that the distribution of the resonance field be in The direction is either an even function or an odd function, therefore the coupling coefficient needs to satisfy... When using a transverse electric field Determine and ( When the phase of ) is , for TE-like and TM-like resonances, we have respectively and Regarding the TE-like bands studied in this chapter, we have Therefore, the following relationship can be derived: Subsequently, substituting this formula into the second equation of the time-coupled mode theory formula, we further obtain the upward radiation amplitude of the structure as follows: in, Therefore, the upward-radiating amplitude is The projection on the plane is: here, It is upward radiation and The angle between the axes, This corresponds to the wave vector radiated upwards. As shown in the formula, the far-field polarization state in momentum space is determined by the interference between radiated waves caused by changes in the structure's thickness. Therefore, the far-field polarization state in momentum space can be manipulated by adjusting the thickness of this single-layer dielectric material structure.

[0028] In some embodiments of the present invention, the material used to prepare the column includes silicon.

[0029] In some embodiments of the present invention, the refractive index of the silicon is 3.5.

[0030] In some embodiments of the present invention, the distance between the centers of the columns is equal along two orthogonal directions.

[0031] In some embodiments of the present invention, the radius of the first column is... The radius of the second column ,in, a The distance between the centers of the cylinders is along two orthogonal directions.

[0032] In some embodiments of the present invention a The wavelength range is 300~700nm.

[0033] The Q value of the polarization state regulated by this scheme is increased by nearly two orders of magnitude, which has broad application prospects in improving the performance of optical devices such as high-power sensors and lasers.

[0034] Figure 2 The figure shows the distribution of intrinsic polarization states under different structural thickness parameters. +1 and -1 in the figure represent the topological charge number of the BIC at that location, respectively, while the yellow and blue dots indicate the presence of right-handed and left-handed circular polarization states, respectively. It can be observed that, while maintaining structural symmetry, when the BIC is stable, the polarization states in its neighborhood cover the range from linear to circular polarization.

[0035] Figure 3 The paper illustrates the distribution relationship between the Q value of the supported BIC neighborhood exhibiting a circularly polarized state and the structural thickness parameter of the structure designed using this invention. The results show that the Q value of the regulated circularly polarized state can reach 10. 5 This demonstrates that the planar dielectric metamaterial designed in this invention can achieve high Q-value polarization control.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A planar dielectric metamaterial with high Q-value polarization modulation, characterized in that, It includes multiple columns arranged in two orthogonal directions in a plane to form an array structure. The multiple columns include multiple first columns and multiple second columns. The diameters of the first columns and the second columns are different. In one orthogonal direction, the columns are of the same type, either first columns or second columns. In the other orthogonal direction, the first columns and the second columns are alternately arranged.

2. The planar dielectric metamaterial with high Q-value polarization modulation according to claim 1, characterized in that, The midpoints of the axial segments of all the columns lie in the same plane, making the metamaterial symmetrical about this plane along the thickness direction.

3. The planar dielectric metamaterial with high Q-value polarization modulation according to claim 1, characterized in that, The design method of the metamaterial is to adjust the polarization direction by adjusting the thickness of the column.

4. The planar dielectric metamaterial with high Q-value polarization modulation according to claim 1, characterized in that, The column is made of silicon.

5. The planar dielectric metamaterial with high Q-value polarization modulation according to claim 4, characterized in that, The silicon has a refractive index of 3.

5.

6. The planar dielectric metamaterial with high Q-value polarization modulation according to claim 1, characterized in that, The distance between the centers of the columns is equal along two orthogonal directions.

7. The planar dielectric metamaterial with high Q-value polarization modulation according to claim 6, characterized in that, The radius of the first column The radius of the second column ,in, a The distance between the centers of the cylinders is along two orthogonal directions.

8. The planar dielectric metamaterial with high Q-value polarization modulation according to claim 7, characterized in that, a The wavelength range is 300~700nm.

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