A structure for realizing Fano resonance based on edge mode

Abstract

The present invention provides a structure for realizing Fano resonance based on edge modes. The structure for Fano resonance includes a metal layer, in which an input channel, an output channel, and a resonant cavity are formed; the resonant cavity is a symmetric structure and is located at the central position within the metal layer; the resonant cavity is directly coupled to the input channel and the output channel respectively. The input channel communicates with one side of the resonant cavity, the output channel communicates with the other side of the resonant cavity, and the input channel and the output channel are on the same straight line; the input channel and the output channel are filled with air, and the resonant cavity is filled with a refractive material; the incident light of the resonance system can pass through the input channel and excite the edge modes within the resonant cavity, thereby obtaining a Fano line shape. The structure for realizing Fano resonance based on edge modes provided by the present invention further enriches the method for realizing the Fano resonance phenomenon based on the MIM waveguide, simplifies the structural system for realizing the Fano line shape, and can provide new ideas for the miniaturization and integration development of multifunctional micro-nano optical devices.

Description

Technical Field

[0001] The present invention belongs to the technical field of Fano resonance structures, and particularly relates to a structure for realizing Fano resonance based on edge modes. Background Art

[0002] Fano resonance is a special resonance phenomenon, usually generated by the coherent coupling of a local discrete state and a broadband continuous state; different from Lorentz resonance, Fano resonance exhibits a steep and highly asymmetric response spectrum, that is, the response spectrum can rapidly rise from the trough to the peak or fall from the peak to the trough. This characteristic enables the Fano line shape to have a very wide range of applications, which is beneficial to reducing the pumping threshold of surface plasmon modulators, increasing the resolution of surface plasmon wave demultiplexers, and improving the sensitivity of refractive index sensors; researchers have achieved Fano resonance in surface plasmon micro-nano structure systems such as noble metal nanoparticles, metal polymers, hybrid waveguide systems, metamaterial systems, and metal-insulator-metal (MIM) waveguides. The proposed of these structure systems further enriches and expands the applications of the Fano resonance phenomenon; among them, the MIM waveguide system can localize light waves between two layers of metal, having very good light field localization characteristics and a very long propagation distance. Therefore, the research on the Fano resonance phenomenon based on MIM waveguides has received increasing attention; in the prior art, researchers have designed various resonator systems based on MIM waveguides to achieve Fano resonance, such as multi-resonator coupling, metal baffle and resonator coupling, symmetry-breaking systems, etc. However, with the increasing research on the Fano resonance phenomenon based on MIM waveguides, the overall structure of the designed system becomes more and more complex, which undoubtedly brings great challenges to processing and etching.

[0003] Based on the technical problems existing in the above Fano resonance structures, there is no relevant solution; therefore, it is urgent to seek an effective solution to solve the above problems. Summary of the Invention

[0004] The object of the present invention is to propose a new mechanism for realizing the Fano resonance phenomenon based on the MIM waveguide structure system in view of the deficiencies in the above technologies, aiming to solve one of the problems that the existing Fano resonance structures are relatively complex, too large in volume, and inconvenient for processing.

[0005] The present invention provides a structure for realizing Fano resonance based on an edge mode. The structure for Fano resonance includes a metal layer, in which an input channel, an output channel, and a resonant cavity are formed; the resonant cavity is a symmetric structure and is located at the central position within the metal layer; the resonant cavity is directly coupled to the input channel and the output channel respectively. The input channel communicates with one side of the resonant cavity, the output channel communicates with the other side of the resonant cavity, and the input channel and the output channel are located on the same straight line; the input channel and the output channel are filled with air, and the resonant cavity is filled with a refractive material; the incident light of the resonance system can pass through the input channel and excite the edge mode within the resonant cavity, realizing the steep - rising feature in the transmission spectrum of the system, thereby obtaining a Fano line shape.

[0006] Further, the resonant cavity is an X - type resonant cavity, and the X - type resonant cavity is obtained by an N - th interpolation curve equation through given coordinate points; the X - type resonant cavity is symmetric along the Y - direction and the X - direction.

[0007] Further, the X - type resonant cavity is determined by a 16 - th interpolation curve, and the required 17 control - point coordinates are respectively: k is a scale factor.

[0008] Further, the metal layer is a silver - based metal layer; the refractive material is air.

[0009] Further, the dispersion relation of the silver - based metal layer is represented by the Drude model: (ε ∞ , ω p , γ)=(3.7, 9.1eV, 0.018eV), where ε ∞ is the infinite dielectric constant, ω p is the plasma oscillation frequency, and γ is the collision frequency.

[0010] Further, the incident light wave is a transverse magnetic wave (TM0).

[0011] Further, the wavelength range of the incident light is 600nm - 2000nm.

[0012] Further, the widths w of the input channel and the output channel are the same.

[0013] Further, the widths of both the input channel and the output channel are 50nm to 100nm.

[0014] Further, the structure for Fano resonance can be used in micro - nano optical devices.

[0015] The structure for realizing Fano resonance based on edge mode provided by the present invention is based on the ultra-strong optical field localization characteristics of the MIM waveguide. By exciting the edge mode in the X-shaped resonator, the steep rise feature in the transmission spectrum of the system is realized, and a Fano line shape is obtained. The structure for Fano resonance consists of only an X-shaped resonator coupled with the MIM waveguide, which effectively simplifies the structural system for realizing Fano resonance. The method for realizing Fano resonance by exciting the edge mode further expands and enriches the research on the Fano resonance phenomenon, providing new design ideas for the miniaturization and integration development of multifunctional micro-nano optical devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0017] The present invention will be further described below with reference to the drawings:

[0018] Figure 1 It is a schematic diagram of the structure for realizing Fano resonance based on edge mode of the present invention;

[0019] Figure 2 It is the transmission spectrum of the structure simulation test for realizing Fano resonance based on edge mode of the present invention;

[0020] Figure 3 It is the distribution diagram of the normalized magnetic field modulus value when light with a wavelength of λ = 735 nm is incident on the present invention;

[0021] Figure 4 It is the distribution diagram of the normalized magnetic field modulus value when light with a wavelength of λ = 806 nm is incident on the present invention;

[0022] Figure 5 It is the distribution diagram of the normalized magnetic field modulus value when light with a wavelength of λ = 1098 nm is incident on the present invention;

[0023] Figure 6 It is the transmission spectrum of the present invention with different scale factors.

[0024] In the figure: 1 - input channel; 2 - output channel; 3 - resonator; 4 - refractive material; 5 - metal layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0027] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined. "Several" means one or more unless otherwise specifically defined.

[0028] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation on the present invention.

[0029] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] Such as Figure 1As shown in the figure, the present invention provides a structure for realizing Fano resonance based on edge mode. The structure of the Fano resonance includes a metal layer 5, and an input channel 1, an output channel 2 and a resonant cavity 3 are formed in the metal layer 5; wherein, the resonant cavity 3 is a symmetric structure and is located at the central position within the metal layer 5, and the input channel 1, the output channel 2 and the resonant cavity 3 are respectively embedded within the metal layer 5; further, the resonant cavity 3 is directly coupled to the input channel 1 and the output channel 2 respectively. The input channel 1 communicates with one side of the resonant cavity 3, the output channel 2 communicates with the other side of the resonant cavity 3, and the input channel 1 and the output channel 2 are located on the same straight line; further, the input channel 1 and the output channel 2 are filled with air, and the resonant cavity 3 is filled with a refractive material 4. The incident light excites the surface plasmon polaritons of the system through the input channel 1; specifically, the incident light of the resonance system can pass through the input channel 1 and excite the edge mode within the resonant cavity 3, realizing the steep rise feature in the transmission spectrum of the system, thereby obtaining the Fano line shape; the structure for realizing Fano resonance based on edge mode provided by the present invention is based on the ultra-strong optical field localization characteristics of the MIM waveguide. By exciting the edge mode within the X-shaped resonant cavity, the steep rise feature in the transmission spectrum of the system is realized, and the Fano line shape is obtained; the structure of the Fano resonance is only composed of an X-shaped resonant cavity coupled with the MIM waveguide, which effectively simplifies the structural system for realizing Fano resonance, facilitates processing and forming, and the method for realizing Fano resonance by exciting the edge mode further expands and enriches the research on the Fano resonance phenomenon, and can provide new design ideas for the miniaturization and integration development of multifunctional micro-nano optical devices.

[0031] Preferably, in combination with the above solution, as Figure 1 shown, the resonant cavity 3 is an X-shaped resonant cavity, and the X-shaped resonant cavity is obtained by the N-th interpolation curve equation through given coordinate points; the X-shaped resonant cavity is symmetric along the Y direction and the X direction.

[0032] Preferably, in combination with the above solution, as Figure 1 shown, the X-shaped resonant cavity is determined by a 16th-degree interpolation curve, and the required 17 control point coordinates are respectively:

[0033] k is a scaling factor, and k is used to control the size of the X-shaped resonant cavity, thereby adjusting the position of the Fano peak. Specifically, the value range of k is preferably from 1.00 to 1.50, and can be specifically 1.25, 1.34; further, the input channel 1 and the output channel 2 are directly coupled to the X-shaped resonant cavity respectively; further, the internal media of the input channel 1 and the output channel 2 are air, while the internal medium of the X-shaped resonant cavity is air or other refractive index materials.

[0034] Preferably, in combination with the above solution, as Figure 1As shown, the metal layer 5 is a silver metal layer; the refractive material 4 is air or other refractive index materials; further, all the calculation results in the present invention are completed based on the finite element method; in the structural system for realizing Fano resonance based on edge mode provided by the present invention, when the metal layer and the metal-loaded material are gold, similar results are also obtained.

[0035] Preferably, in combination with the above solution, as Figure 1 shown, the dispersion relation of the silver metal layer is represented by the drude model: (ε ∞ , ω p , γ) = (3.7, 9.1eV, 0.018eV), where ε ∞ is the infinite dielectric constant, ω p is the plasma oscillation frequency, and γ is the collision frequency; in the MIM waveguide, only the TM0 wave can excite its surface plasmon polariton effect. Therefore, the incident light wave selects the TM0 wave.

[0036] Preferably, in combination with the above solution, as Figure 1 shown, the wavelength range of the incident light is 600nm to 2000nm, specifically it can be 1200nm, 1650nm; in order to explore whether the structure of this Fano resonance can generate a Fano line shape with asymmetric characteristics; the present application's solution performs simulation calculations on the Figure 1 transmission characteristics of the shown structure, and the obtained transmission spectrum is as Figure 2 shown (at this time k = 1.00 and the refractive index of the medium inside the X-shaped resonator is n = 1.0); it can be seen from this that the system has generated a total of three resonance peaks, P1, λ = 735nm, P2, λ = 806nm, and P3, λ = 1098nm), where the P1 peak is a typical Fano line shape, and its rise from the trough to the peak is only 27nm. This steep rise characteristic will make it have very important applications in high-sensitivity refractive index sensors;

[0037] Further, Figure 3 , Figure 4 and Figure 5 respectively give the normalized magnetic field modulus distribution diagrams of the positions of the three resonance peaks; it can be seen from Figure 3 that the optical field mode is mainly concentrated on the arc edge of the X-shaped resonator, that is, the edge mode of the X-shaped resonator is excited; Figure 4 and Figure 5 respectively correspond to the high-order mode and the fundamental mode of the Lorentz line shape, and their optical field modes are mainly concentrated at the four corners of the X-shaped resonator and between the main channels; through the analysis of the optical field mode distribution, it can be clearly known the influencing factors of each resonance peak, and then the required wavelength can be selected through the optimization design of the parameters.

[0038] As Figure 6As shown, the variation law of the transmission spectrum at different scaling factors was calculated. It can be seen from this that as the scaling factor k increases, all three resonance peaks in the transmission spectrum exhibit a linear redshift. This linear variation law has good guiding significance for the design of specific wavelength selection. In addition, by changing the refractive index of the material inside the X-shaped resonator, a linear redshift law of the resonance peak can also be obtained, enabling the structure of this Fano resonance to be used as a refractive index sensor device with good performance. These characteristics enable the present invention to have a very wide range of applications in multifunctional micro-nano optical devices. In addition, by finely tuning the coordinate points in the y direction of the X-shaped resonator, while still maintaining the overall symmetry of the system with respect to the x and y directions, two Fano peaks can be generated in the transmission spectrum of the system. This design of realizing Fano resonance using only a single symmetric resonator effectively simplifies the micro-nano structure system and facilitates processing and shaping, providing a new idea for the future realization of highly integrated micro-nano optical devices.

[0039] Preferably, in combination with the above solution, as Figure 1 shown, the widths w of the input channel 1 and the output channel 2 are the same; further, the widths of both the input channel 1 and the output channel 2 are from 50 nm to 100 nm, and further, the widths of both the input channel 1 and the output channel 2 are 50 nm, 65 nm, and 78 nm.

[0040] Preferably, in combination with the above solution, as Figure 1 shown, the structure for realizing Fano resonance based on the edge mode provided by the present invention can be used in micro-nano optical devices, thereby reducing the volume of the micro-nano optical devices and enabling an integrated design; the present invention obtains a Fano line shape only by exciting the edge mode of the X-shaped resonator in the MIM waveguide. The technical solution is simple and highly operable, enriching the research methods of Fano resonance based on the MIM waveguide and expanding the application range of using the Fano line shape to realize high-performance micro-nano optical devices.

[0041] Based on the X-shaped resonator in the MIM waveguide, the present invention proposes a structure for realizing Fano resonance by exciting the edge mode of the X-shaped resonator. This structure system is relatively simple and consists of an input channel, an output channel, and an X-shaped resonator embedded in a metal layer. Among them, the X-shaped resonator is directly coupled to the input and output channels respectively, which will effectively reduce the difficulty of device processing and etching. The X-shaped resonator is determined by a 16th-degree interpolation curve through 17 given coordinate points. The proposed system enables a Fano line shape to be obtained only through a single symmetric resonator, which effectively simplifies the structural design for realizing the Fano resonance phenomenon. The method of realizing Fano resonance by exciting the edge mode of the resonator further enriches the research means of the Fano resonance phenomenon. Moreover, by adjusting the scaling factor that generates the X-shaped resonator, the position of the Fano peak can be effectively adjusted.

[0042] The above are only the preferred embodiments of the present invention, and do not impose any formal restrictions on the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make many possible changes and modifications to the technical solution of the present invention by using the above-mentioned technical content, or modify it into equivalent embodiments with equivalent changes. Therefore, all changes, modifications, equivalent changes and modifications made to the above embodiments based on the technology of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of this technical solution.

Claims

1. A structure for realizing Fano resonance based on edge mode, characterized in that, The structure of the Fano resonance includes a metal layer (5), in which an input channel (1), an output channel (2) and a resonant cavity (3) are formed; the resonant cavity (3) is a symmetric structure and is located at the central position within the metal layer (5); the resonant cavity (3) is directly coupled to the input channel (1) and the output channel (2) respectively, the input channel (1) communicates with one side of the resonant cavity (3), the output channel (2) communicates with the other side of the resonant cavity (3), and the input channel (1) and the output channel (2) are located on the same straight line; the input channel (1) and the output channel (2) are filled with air, and the resonant cavity (3) is filled with a refractive material (4); the incident light of the resonance system can pass through the input channel (1) and excite the edge mode within the resonant cavity (3), thereby obtaining a Fano line shape.

2. The structure for realizing Fano resonance based on an edge mode according to claim 1, wherein The resonant cavity (3) is an X-shaped resonant cavity, and the X-shaped resonant cavity is obtained from an Nth-order interpolation curve equation through given coordinate points; The X-shaped resonant cavity is symmetric along the Y direction and the X direction.

3. The structure for implementing Fano resonance based on an edge mode according to claim 2, wherein The X-shaped resonant cavity is determined by a 16th-order interpolation curve, and the required 17 control point coordinates are respectively: The k is a scale factor.

4. The structure for implementing Fano resonance based on edge mode according to claim 1, wherein The metal layer (5) is a silver metal layer; the refractive material (4) is air.

5. The structure for implementing Fano resonance based on an edge mode according to claim 4, wherein The dispersion relation of the silver metal layer is represented by the Drude model: (ε ∞ , ω p , γ) = (3.7, 9.1 eV, 0.018 eV), where ε ∞ is the infinite dielectric constant, ω p is the plasma oscillation frequency, and γ is the collision frequency.

6. The structure for realizing Fano resonance based on an edge mode according to claim 1, wherein, The incident light wave is a transverse magnetic wave (TM0).

7. The structure for realizing Fano resonance based on edge mode according to claim 1, wherein The wavelength range of the incident light is 600 nm to 2000 nm.

8. The structure for realizing Fano resonance based on edge mode according to claim 1, characterized in that, The widths w of the input channel (1) and the output channel (2) are the same.

9. The structure for realizing Fano resonance based on an edge mode according to claim 1, wherein The widths of both the input channel (1) and the output channel (2) are from 50 nm to 100 nm.

10. The structure for implementing Fano resonance based on edge mode according to claim 1, characterized in that, The structure of the Fano resonance can be used in micro-nano optical devices.

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