Terahertz narrow-band band elimination filter based on BIC metasurface

Abstract

The utility model relates to a terahertz narrow-band band elimination filter based on a BIC metasurface, which comprises a plurality of filtering units arranged periodically, and the structural composition of each filtering unit is the same. The filtering unit comprises a substrate, and a first structure, a second structure, a third structure and a fourth structure which are distributed on the substrate along the anticlockwise direction, and the first structure, the second structure, the third structure and the fourth structure are the same in structure composition. According to the BIC metasurface-based narrowband band elimination filter provided by the utility model, the symmetry of the filtering unit structure is changed by introducing periodic disturbance, so that quasi-BIC resonance can be realized, and dot frequency filtering can be realized.

Description

Technical Field

[0001] The utility model relates to the technical field of millimeter wave communication equipment and accessories used therein, and in particular to a terahertz narrowband rejection filter based on a BIC metasurface. Background Art

[0002] Electromagnetic metasurfaces are innovative artificial electromagnetic materials whose unique microstructures enable precise control of electromagnetic wave propagation and radiation. Through carefully designed microscopic units, electromagnetic metasurfaces achieve frequency selectivity, phase regulation, polarization control, and wavefront modulation of electromagnetic waves. This makes electromagnetic metasurfaces promising for broad applications in communications, radar, imaging, and optics. Their compactness and lightweight nature allow for smaller and more portable devices, while also opening up new possibilities for electromagnetic wave control and information transmission. Metasurfaces have become a key branch of metamaterials research and hold enormous potential for engineering applications.

[0003] Metasurface band-stop filters are filters designed using metasurfaces. Their advantages include compact size, high flexibility, excellent performance, versatility, and low manufacturing cost. This makes them widely applicable in electromagnetic wave control, including filtering, tuning, beamforming, and radiation control, bringing new innovations to communications, radar, antennas, and other fields.

[0004] Terahertz (THz) waves are electromagnetic waves between microwaves and infrared, with frequencies ranging from approximately 0.1 to 10 THz. THz waves possess many unique properties, such as strong penetration, non-ionization, transparency to many substances, and distinctive optical and electromagnetic characteristics. These properties have led to a wide range of applications in medical imaging, security monitoring, communications, nondestructive testing, and other fields. The development of THz technology is also gradually expanding and deepening the application of THz waves, bringing new possibilities to scientific research and engineering applications in various fields.

[0005] Bound states in the continuum (BICs) are localized modes in an open system that coexist with continuous radiation waves that can carry away energy. BICs provide a new approach to achieving high-quality factor (Q-factor) resonances, theoretically enabling resonances with infinitely high Q-factors. The concept of BICs was first proposed in quantum mechanics and later generalized to a universal wave phenomenon, which has been experimentally verified in various fields. In 2008, Marinica et al. first introduced the concept of BICs into optics using two parallel dielectric gratings and two parallel dielectric cylinders as examples. In 2011, Plotnik et al. first experimentally observed optical phenomena related to BICs using optical waveguide arrays. Ideal BICs exhibit zero-bandwidth resonances in the spectrum, which can only be achieved in lossless and infinite structures. In practice, ideal BICs are difficult to achieve using metasurfaces due to limitations such as material loss, device size constraints, and processing imperfections. Application requirements are generally met by converting ideal BICs into quasi-BIC modes with finitely high Q-factors. High-Q metasurface resonators based on quasi-BICs have shown excellent performance in biochemical sensing, harmonic enhancement, lasers and other fields.

[0006] In view of the above-mentioned defects, the designers have actively carried out research and innovation in order to create a terahertz narrow-band rejection filter based on BIC metasurface to make it more valuable for industrial use. Utility Model Content

[0007] In order to solve any of the above technical problems, the purpose of the present invention is to provide a terahertz narrow-band rejection filter based on a BIC metasurface.

[0008] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0009] A terahertz narrowband band-stop filter based on a BIC metasurface, comprising a plurality of periodically arranged filter units, each of which has the same structural composition;

[0010] The filter unit includes a substrate and a first structure, a second structure, a third structure, and a fourth structure distributed on the substrate in a counterclockwise direction, and the first structure, the second structure, the third structure, and the fourth structure have the same structural composition;

[0011] Before the disturbance is introduced, the first structure and the third structure are symmetrically distributed along the Y-axis, and the second structure and the fourth structure are symmetrically distributed along the X-axis.

[0012] After the disturbance is introduced, the first structure or the third structure shifts in the Y-axis direction, thereby breaking the structural symmetry.

[0013] As a further improvement of the present invention, the substrate is a polyimide structure, and the first structure, the second structure, the third structure and the fourth structure are all silicon structures.

[0014] As a further improvement of the present invention, the cross section of the substrate is a square.

[0015] As a further improvement of the present invention, the period of the substrate is 100-300 μm, and the thickness of the substrate is 200-500 μm.

[0016] As a further improvement of the present invention, the cross sections of the first structure, the second structure, the third structure and the fourth structure are all elliptical.

[0017] As a further improvement of the present invention, the major axis of the ellipse of the first structure, the second structure, the third structure and the fourth structure is 25-40 μm, and the minor axis of the ellipse of the first structure, the second structure, the third structure and the fourth structure is 15-30 μm.

[0018] As a further improvement of the present invention, the horizontal distances from the centers of the first structure, the second structure, the third structure and the fourth structure to the center of the substrate are all equal, which is 40-100 μm.

[0019] As a further improvement of the present invention, the heights of the first structure, the second structure, the third structure and the fourth structure are all equal, i.e., 100-200 μm.

[0020] By means of the above solution, the present invention has at least the following advantages:

[0021] The utility model proposes a narrow-band rejection filter based on a BIC metasurface. By introducing periodic perturbations, the symmetry of the filter unit structure is changed, thereby achieving quasi-BIC resonance and point-frequency filtering.

[0022] The utility model solves the problems of low quality factor, complex structure and low flexibility in the existing waveguide terahertz filter.

[0023] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and to implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 This is a schematic structural diagram of a filter unit of a terahertz narrow-band rejection filter based on a BIC metasurface in the present invention;

[0026] Figure 2 After the disturbance is introduced Figure 1 A top view of

[0027] Figure 3 This is a schematic diagram of the S parameters of the present invention when the terahertz wave is vertically incident under an asymmetric condition (wherein the electric field is along the y direction).

[0028] The meanings of the reference numerals in the figures are as follows.

[0029] Substrate 1, first structure 2, second structure 3, third structure 4, fourth structure 5. DETAILED DESCRIPTION

[0030] The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0031] In order to enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the utility model for which protection is sought, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0032] Example

[0033] like Figures 1 to 3 As shown,

[0034] A terahertz narrowband band-stop filter based on a BIC metasurface includes a plurality of periodically arranged filter units, each of which has the same structural composition.

[0035] The filter unit includes a substrate 1 and a first structure 2, a second structure 3, a third structure 4 and a fourth structure 5 distributed on the substrate 1 in a counterclockwise direction, and the first structure 2, the second structure 3, the third structure 4 and the fourth structure 5 have the same structural composition.

[0036] The substrate 1 is a polyimide structure, and the first structure 2, the second structure 3, the third structure 4 and the fourth structure 5 are all silicon structures.

[0037] The cross section of the substrate 1 is square, the period of the substrate 1 is 100-300 μm, and the thickness of the substrate 1 is 200-500 μm.

[0038] The cross sections of the first structure 2, the second structure 3, the third structure 4 and the fourth structure 5 are all elliptical, the major axes of the ellipses of the first structure 2, the second structure 3, the third structure 4 and the fourth structure 5 are all 25-40 μm, and the minor axes of the ellipses of the first structure 2, the second structure 3, the third structure 4 and the fourth structure 5 are all 15-30 μm.

[0039] The horizontal distances from the centers of the first structure 2 , the second structure 3 , the third structure 4 and the fourth structure 5 to the center of the substrate 1 are all equal, and are 40-100 μm.

[0040] The heights of the first structure 2 , the second structure 3 , the third structure 4 and the fourth structure 5 are all equal, and are 100-200 μm.

[0041] Before the disturbance is introduced, the first structure 2 and the third structure 4 are symmetrically distributed along the Y-axis, and the second structure 3 and the fourth structure 5 are symmetrically distributed along the X-axis.

[0042] After the disturbance is introduced, the first structure 2 or the third structure 4 is offset in the Y-axis direction, thereby breaking the structural symmetry, as shown in FIG. Figure 2 shown.

[0043] By introducing symmetry perturbations to achieve quasi-BIC, resonance with high quality factor is stimulated, and narrowband filtering functions such as Figure 3 shown.

[0044] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implying the number of technical features indicated. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0045] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections, direct connections, indirect connections through an intermediate medium, and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A terahertz narrowband rejection filter based on a BIC metasurface, characterized by: It comprises a plurality of periodically arranged filter units, each of which has the same structural composition; The filtering unit comprises a substrate (1) and a first structure (2), a second structure (3), a third structure (4) and a fourth structure (5) distributed on the substrate (1) in a counterclockwise direction, and the first structure (2), the second structure (3), the third structure (4) and the fourth structure (5) are all of the same structural composition; Before the disturbance is introduced, the first structure (2) and the third structure (4) are symmetrically distributed based on the Y-axis direction, and the second structure (3) and the fourth structure (5) are symmetrically distributed based on the X-axis direction; After the disturbance is introduced, the first structure (2) or the third structure (4) is offset in the Y-axis direction, thereby breaking the structural symmetry.

2. The terahertz narrowband rejection filter based on the BIC metasurface according to claim 1, characterized in that: The substrate (1) is a polyimide structure, and the first structure (2), the second structure (3), the third structure (4) and the fourth structure (5) are all silicon structures.

3. The terahertz narrowband rejection filter based on the BIC metasurface according to claim 1, characterized in that: The cross section of the substrate (1) is square.

4. The terahertz narrowband rejection filter based on a BIC metasurface according to claim 1, characterized in that: The period of the substrate (1) is 100-300 μm, and the thickness of the substrate (1) is 200-500 μm.

5. The terahertz narrowband rejection filter based on the BIC metasurface according to claim 1, characterized in that: The cross sections of the first structure (2), the second structure (3), the third structure (4) and the fourth structure (5) are all elliptical.

6. The terahertz narrow-band rejection filter based on a BIC metasurface according to claim 5, characterized in that: The major axis of the ellipse of the first structure (2), the second structure (3), the third structure (4) and the fourth structure (5) is 25-40 μm, and the minor axis of the ellipse of the first structure (2), the second structure (3), the third structure (4) and the fourth structure (5) is 15-30 μm.

7. The terahertz narrowband rejection filter based on a BIC metasurface according to claim 1, characterized in that: The horizontal distances from the centers of the first structure (2), the second structure (3), the third structure (4) and the fourth structure (5) to the center of the substrate (1) are all equal, and are 40-100 μm.

8. The terahertz narrowband rejection filter based on a BIC metasurface according to claim 1, characterized in that: The heights of the first structure (2), the second structure (3), the third structure (4) and the fourth structure (5) are all equal, and are 100-200 μm.

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