A dielectric-metal bilayer metamaterial high-quality factor electromagnetically induced transparent resonant device

Abstract

This invention discloses a high-quality factor electromagnetically induced transparent resonator device based on a dielectric-metal bilayer metamaterial. The device includes a substrate, dielectric resonator units arranged in a two-dimensional periodic pattern on the upper surface of the substrate, and metal resonator units arranged in a two-dimensional periodic pattern on the lower surface of the substrate. The dielectric and metal resonator units have the same two-dimensional distribution period and arrangement direction. The metal resonator unit is located directly below the dielectric resonator units. The substrate is made of a dielectric material. Each dielectric resonator unit consists of two rectangular dielectric ring pillars with their long sides parallel to each other. The metal resonator unit consists of a rectangular metal strip parallel to the long sides of the two rectangular dielectric ring pillars. This device provides a dielectric-metal bilayer metamaterial-based electromagnetically induced transparent resonator, improving the quality factor of electromagnetically induced transparency and overcoming the shortcomings of existing technologies, such as low quality factors and complex adjustment mechanisms.

Description

Technical Field

[0001] This invention relates to a high-quality factor electromagnetically induced transparent resonant device of a dielectric-metal bilayer metamaterial, belonging to the field of metamaterials technology. Background Technology

[0002] Electromagnetic induction transparency (EIT) is a concept observed in atomic physics, generated by quantum interference. It has since been extended to classical optical systems using plasmonic metamaterials. Metamaterial-based EIT refers to the phenomenon of achieving electromagnetically induced transparency by simulating atomic systems with metamaterials. In recent years, metasurface-based EIT has become a research hotspot in nano-optics due to its ability to generate high quality factor resonances, offering a potential solution to the long-standing problem of metamaterial loss. Metamaterial-based ring dipole responses, due to their novel electromagnetic properties, can generate high quality factor resonances, making them a focus in nanophotonics. High quality factor resonances can be applied to narrowband filters, low-loss slow-light devices, and high-sensitivity optical sensors.

[0003] Currently, there are few reports on achieving electromagnetically induced transparency (EIT) using dielectric-metal bilayer metamaterials. The metal-dielectric bilayer hybrid metamaterial mentioned in patent CN108110396 A generates EIT by coupling an array of dielectric rods with an array of metal strips. To change the resonance quality factor of the dielectric structure while maintaining the resonant wavelength, it is necessary to simultaneously change the basic parameters of the structure, such as length, width, and height, thereby altering the resonance quality factor of the bilayer hybrid metamaterial's EIT. The tuning mechanism is complex. How to design the resonant structure and simplify the tuning mechanism is a problem that researchers need to solve. Summary of the Invention

[0004] The purpose of this invention is to provide a dielectric-metal bilayer metamaterial-like electromagnetically induced transparent resonant device, which improves the quality factor of electromagnetically induced transparency and overcomes the shortcomings of existing technologies, such as low quality factor and complex adjustment mechanism.

[0005] To achieve the above objectives, the technical solution adopted by this invention is: a high-quality factor electromagnetically induced transparent resonant device based on a dielectric-metal bilayer metamaterial, characterized in that it includes a substrate, and dielectric resonant units and metal resonant units, both arranged in a two-dimensional periodic distribution, disposed on the upper and lower surfaces of the substrate. The substrate is made of a dielectric material. The dielectric resonant units and the metal resonant units have the same two-dimensional distribution period and arrangement direction, with the metal resonant units located directly below the dielectric resonant units.

[0006] The dielectric resonator unit consists of two rectangular dielectric ring pillars with their long sides parallel to each other. The metal resonator unit consists of a rectangular metal strip with its long sides parallel to the long sides of the two rectangular dielectric ring pillars.

[0007] Furthermore, the quality factor of the generated electromagnetic induced transparency is related to the spacing g between the two rectangular dielectric cylinders in the short side direction of the dielectric resonator unit; when g increases, the quality factor of the generated electromagnetic induced transparency increases, while the resonant center wavelength remains basically unchanged; when g decreases, the quality factor of the generated electromagnetic induced transparency decreases, while the resonant center wavelength remains basically unchanged.

[0008] Furthermore, the substrate thickness t needs to satisfy 0.08λ < t < 0.95λ, where λ is the resonant center wavelength of the electromagnetic induced transparency-like. When g is fixed, increasing the thickness t can improve the quality factor of the electromagnetic induced transparency.

[0009] Furthermore, the length h of the rectangular metal strip needs to satisfy 0.44λ < h < 0.48λ, where λ is the resonant center wavelength of the electromagnetic induced transparency-like.

[0010] Furthermore, the length b of the rectangular dielectric cylinder needs to satisfy 0.4λ < b < 0.56λ, the width a of the rectangular dielectric cylinder needs to satisfy 0.28λ < a < 0.30λ, and the line width w of the rectangular dielectric cylinder needs to satisfy 0.08λ < w < 0.11λ; the spacing g between the two rectangular dielectric cylinders needs to satisfy 0.023λ < g < 0.08λ, where λ is the resonant center wavelength of the electromagnetic induced transparency-like.

[0011] Compared with the prior art, the present invention has the following advantages:

[0012] Compared with other dielectric-metal bilayer metamaterial electromagnetic induced transparency-like resonant devices, the present invention only needs to change the spacing g between the two rectangular dielectric cylinders in the dielectric resonator unit, without changing the geometric parameters of the structure, to adjust the quality factor of the electromagnetic induced transparency-like. The present invention can also improve the quality factor by appropriately adjusting the thickness t of the intermediate substrate, and the method of improving the quality factor is relatively flexible and convenient.

[0013] The present invention utilizes the dielectric-metal bilayer metamaterial technology, improves the quality factor of the electromagnetic induced transparency-like in the bilayer metamaterial, and the implementation method is relatively flexible and convenient. The present invention provides a flexible and feasible platform for the research of biosensing, nonlinear devices and optical nano-devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic structural diagram (partial) of the present invention;

[0015] Figure 2 is Figure 1 the right view of, in which the dielectric resonator unit 2 and the rectangular metal strip 3 are respectively located on the upper surface and the lower surface of the substrate 1;

[0016] Figure 3 is Figure 1 Top view;

[0017] Figure 4 for Figure 1 The resonant device shown is a transmittance curve of a single-layer dielectric metamaterial, a single-layer metallic metamaterial, and a double-layer hybrid metamaterial in the range of 0.14-0.3THz, obtained from finite element calculations.

[0018] Figure 5 for Figure 1 The curves shown represent the relationship between the resonant quality factor and the distance g between the two rectangular dielectric ring pillars.

[0019] Figure 6 for Figure 1 The curves shown represent the relationship between the resonant device and the resonant quality factor corresponding to different substrate thicknesses t. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the accompanying drawings. Figure 1 , Figure 2 and Figure 3 The structure of a dielectric-metal bilayer metamaterial high-quality factor electromagnetically induced transparent resonator device according to the present invention is shown. For example... Figure 1 and Figure 2 As shown, the dielectric-metal bilayer metamaterial high-quality factor electromagnetically induced transparent resonator includes a substrate 1, dielectric resonator units 2 located on the upper and lower surfaces of the substrate 1, and a rectangular metal strip 3. The substrate is made of a dielectric material. Both the dielectric resonator units 2 and the rectangular metal strip 3 are arranged in a two-dimensional periodic pattern, with the same two-dimensional distribution period and arrangement direction. The metal resonator units are located directly below the dielectric resonator units. Figure 1 As shown, the dielectric resonator unit consists of two rectangular dielectric ring pillars, with the direction of the shorter side of the outer ring pillar defined as the X direction and the direction of the longer side of the outer ring pillar defined as the Y direction. The resonant device of this invention has a period Px along the X direction and a period Py along the Y direction. Figure 1 As shown, a is the width of the rectangular dielectric ring, b is the length of the rectangular dielectric ring, c is the height of the rectangular dielectric ring, d is the width of the rectangular metal strip, e is the height of the rectangular metal strip, and t is the thickness of the substrate. Figure 2 As shown, h is the length of the rectangular metal strip, such as... Figure 3 As shown, w is the thickness of the rectangular dielectric ring, and g is the distance between the two rectangular dielectric rings.

[0021] In the implementation process of the present invention, the resonant frequency I of the dielectric resonant unit is changed by adjusting the width a, length b, and height c of the rectangular dielectric ring column; the resonant frequency II of the metal resonant unit is changed by adjusting the length h and width d of the rectangular metal strip; the resonance generated by the dielectric resonant unit is an annular dipole resonance with a high quality factor. The resonance generated by the metal resonant unit is a dipole resonance with a low quality factor. When the resonant frequency I and the resonant frequency II are close, a high-quality factor electromagnetic induced transparency (EIT) phenomenon is generated. The quality factor of the generated EIT is related to the distance g between the two rectangular dielectric ring columns of the dielectric resonant unit in the short side direction: when g increases, the quality factor of the generated EIT increases, and the resonant center wavelength remains basically unchanged; when g decreases, the quality factor of the generated EIT decreases, and the resonant center wavelength remains basically unchanged.

[0022] In the present invention, the dielectric resonant unit 1 is composed of two rectangular dielectric ring columns symmetrically mirror-imaged, and the substrate thickness t needs to satisfy 0.08λ < t < 0.95λ. When g is fixed, increasing the thickness t can improve the quality factor of the electromagnetic induced transparency. The length h of the rectangular metal strip needs to satisfy 0.44λ < h < 0.48λ; the length b of the rectangular dielectric ring column needs to satisfy 0.4λ < b < 0.56λ, the width a of the rectangular dielectric ring column needs to satisfy 0.28λ < a < 0.30λ, the line width w of the rectangular dielectric ring column needs to satisfy 0.08λ < w < 0.11; the distance g between the two rectangular dielectric ring columns needs to satisfy 0.023λ < g < 0.08λ, where λ is the resonant center wavelength of the electromagnetic induction transparency-like.

[0023] The following takes specific embodiments to illustrate the technical effects of the present invention.

[0024] This embodiment operates near 0.24 THz in the terahertz band. When it works, the electromagnetic wave is incident normally along the Z direction and is linearly polarized light incident, and the polarization direction is along the Y direction. The material of the dielectric resonant unit 1 on the upper surface is silicon with a dielectric constant of 11.9; the material of the substrate 2 is polyethylene terephthalate (PET) with a dielectric constant of 1.5; the material of the rectangular metal strip 3 on the lower surface is aluminum.

[0025] The designed structure of this embodiment has a period length Px along the X direction and a period length Py along the Y direction both of 900 microns each. The width a of the rectangular dielectric ring column is 360 microns, the length b of the rectangular dielectric ring column is 600 microns, the height c of the rectangular dielectric ring column is 100 microns, the thickness w of the rectangular dielectric ring column is 100 microns, the distance g between the two rectangular dielectric ring columns is 60 microns, the width d of the rectangular metal strip 3 is 60 microns, the length h of the rectangular metal strip 3 is 570 microns, the height e of the rectangular metal strip is 2 microns, and the thickness t of the substrate 2 is 1200 microns.

[0026] When the structural dimensions are as described above, the transmittance spectrum of the dielectric-metal bilayer metamaterial electromagnetically induced transparent resonator, calculated using the finite element method in the range of 0.14-0.3 THz, is as follows: Figure 4 As shown in the figure, the short dashed line represents the transmittance curve of a single-layer dielectric resonant unit, which produces a ring couple resonance with a quality factor of 1110 (when g = 90 micrometers, the quality factor can reach up to 1.8 × 10⁻⁶). 8 The long dashed line in the figure represents the electric dipole resonance generated by a single-layer metal resonant unit, with a quality factor of 6.3. The solid line represents the EIT-like curve generated by the dielectric-metal bilayer metamaterial-like electromagnetically induced transparent resonator in this frequency range, with a center frequency of 0.238 THz (wavelength of 1260 micrometers), a resonant amplitude of up to 0.98, and a quality factor of 20971. The quality factor of the resonance is given by the formula Q = f0 / Δf (where f0 is the resonant frequency corresponding to the resonant peak, and Δf is the width of the resonant frequency corresponding to half the maximum amplitude of the resonant peak in the electromagnetically induced transparent window).

[0027] It should be noted that the quality factor of the electromagnetically induced transparency is related to the distance g between the two rectangular dielectric ring pillars in the short side direction of the dielectric resonator unit. Figure 5 This represents the quality factor of EIT for different spacings g between two rectangular dielectric ring pillars when the substrate thickness is 1200 μm. Figure 5 As shown, when g increases, the coupling between the dielectric resonator and the metal resonator increases, resulting in an increase in the quality factor of electromagnetically induced transparency; conversely, when g decreases, the coupling between the dielectric resonator and the metal resonator decreases, resulting in a decrease in the quality factor of electromagnetically induced transparency. In particular, similar to the metal-dielectric bilayer hybrid metamaterial mentioned in the previously introduced CN108110396 A patent, this invention can also adjust the quality factor by adjusting the substrate thickness t. Figure 6 This represents the quality factor of EIT for different substrate thicknesses t. For example... Figure 6 As shown, by fixing g at 100 μm, the quality factor of the resonance can also be improved by increasing the substrate thickness t. This method is also applicable to different g values.

[0028] In addition, the resonant device of the present invention can also be used in optical bands, microwave bands, and other bands.

Claims

1. A dielectric-metal bilayer metamaterial high-quality factor electromagnetically induced transparent resonant device, characterized in that: It includes a substrate, dielectric resonant units that are two-dimensionally periodically distributed on the upper surface of the substrate, and metal resonant units that are two-dimensionally periodically distributed on the lower surface of the substrate. The substrate is made of a dielectric material. The dielectric resonant units and the metal resonant units have the same two-dimensional distribution period and arrangement direction. The metal resonant unit is located directly below the dielectric resonant unit. The dielectric resonant unit is composed of two rectangular dielectric cylinders, the long sides of the two rectangular dielectric cylinders are parallel to each other. The metal resonant unit is composed of a rectangular metal strip, and the rectangular metal strip is parallel to the long sides of the two rectangular dielectric cylinders. The quality factor of the generated electromagnetic induced transparency is related to the spacing g between the two rectangular dielectric cylinders in the short side direction in the dielectric resonant unit. When g increases, the quality factor of the generated electromagnetic induced transparency increases, while the resonant center wavelength remains basically unchanged. When g decreases, the quality factor of the generated electromagnetic induced transparency decreases, while the resonant center wavelength remains basically unchanged.

2. The dielectric-metal bilayer metamaterial high-quality factor electromagnetically induced transparent resonator device according to claim 1, characterized in that... The substrate thickness t needs to satisfy 0.08λ < t < 0.95λ. When g is fixed, increasing the thickness t can improve the quality factor of electromagnetic induced transparency, where λ is the resonant center wavelength of the electromagnetic induced transparency-like.

3. For the dielectric-metal bilayer metamaterial high-quality factor electromagnetic induced transparency-like resonant device according to claim 1, the length h of the rectangular metal strip needs to satisfy 0.44λ < h < 0.48λ, where λ is the resonant center wavelength of the electromagnetic induced transparency-like.

4. The dielectric-metal bilayer metamaterial high-quality factor electromagnetic induction transparent resonator device according to claim 1, characterized in that, In the implementation process, the length b of the rectangular dielectric cylinder needs to satisfy 0.4λ < b < 0.56λ, the width a of the rectangular dielectric cylinder needs to satisfy 0.28λ < a < 0.30λ, and the line width w of the rectangular dielectric cylinder needs to satisfy 0.0λ < w < 0.11λ, where λ is the resonant center wavelength λ of the electromagnetic induced transparency-like.

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