CN208723068U - A multiple resonant cavity based on multiple metal composite nano-dielectric pillars - Google Patents

Abstract

The utility model discloses a kind of multiple resonant cavities based on multiple metal composite nano dielectric posts, belong to electromagnetic technology field.The multiple resonant cavity of the utility model is made of three layers of 18 metal composite nano dielectric posts altogether, and 6 metal composite nano dielectric posts of first layer press rectangular arranged, each 6 of second and third layer are evenly distributed in respectively on inside and outside two circles；The structure constitutes 9 cavitys of 4 kinds of difference in size.The multiple resonant cavity of the utility model passes through the gap between dielectric posts, by external excitation resonance, the resonance plasma wave of incidence wave excitation simultaneously forms six kinds of entirely different resonance mechanism by 9 cavitys of 4 kinds of different sizes in different frequency, the plasma wave for exciting resonance to the incidence wave of different frequency is realized by the size of the material and thickness and the relative dielectric constant of innermost layer dielectric core that change metal coating, realizes the diversified multiple cavity resonator structure of different frequency.

Description

A multiple resonant cavity based on multiple metal composite nano-dielectric pillars

technical field

The utility model belongs to the field of electromagnetic technology, in particular to an electromagnetic resonance cavity, and more particularly to a multiple resonance cavity based on a plurality of metal composite nanometer dielectric columns.

Background technique

The resonant cavity of ordinary electromagnetic waves must be fed in the cavity to effectively resonate, and when the size and shape of the ordinary electromagnetic resonant cavity are determined, the resonant mode can only be determined low-frequency and high-frequency resonant modes, and the general electromagnetic resonant cavity can only resonate effectively. The geometric size of , determines the resonant frequency.

With the rapid development of nanotechnology, nano-metal materials are different from pure dielectric nano-pillar materials. They not only have the excellent properties of nano-materials, but also integrate the unique characteristics of metals, so they show unique properties in the fields of physics and chemistry. The impact of the application of nano-metal materials in basic research in various fields is remarkable. In particular, precious metals such as gold and silver can be used for the coating layer and have good optical properties. In addition, some metal nanomaterials are sensitive to temperature, light, sound and gas, and nanometer metal materials can be used to prepare sensors that meet different performance requirements. In the field of nanophotonics, surface plasmon optics has gradually highlighted its advantages. Metal surface plasmon is a unique surface electromagnetic wave, which is essentially formed by the interaction of incident light and free electrons inside the metal. Surface plasmon is generated at the interface surface of metal and medium. Surface plasmon is a photon-electron coupled state formed by the interaction between photons and free electrons on the metal surface. This coupled state makes the surface plasmon localized field enhanced.

SUMMARY OF THE INVENTION

Aiming at the above-mentioned shortcomings and deficiencies of traditional electromagnetic resonators, the purpose of the present invention is to provide a multi-resonator structure composed of three-layer metal composite nano-dielectric columns, which has unique optical characteristics and resonant modes.

In order to solve the above-mentioned problems, the technical scheme adopted by the present utility model is as follows:

A multiple resonant cavity based on a plurality of metal composite nano-dielectric columns, comprising 18 metal composite nano-dielectric columns respectively arranged in an inner layer area, a middle layer area and an outer layer area, the inner layer area, the middle layer area and the outer layer area. The center points of the regions are coincident; 6 metal composite nano-media columns in the 18 metal composite nano-media columns are arranged in a rectangle in the inner layer region, and the other 6 metal composite nano-media columns in the 18 metal composite nano-media columns are arranged in a rectangle. The dielectric columns are uniformly arranged in a circle in the middle layer area, the remaining 6 metal composite nanometer dielectric columns in the 18 metal composite nanometer dielectric columns are uniformly arranged in a circle in the outer layer area, and the metal composite nanometer medium columns in the middle layer area are uniformly arranged in a circle. The dielectric pillars and the metal composite nano dielectric pillars in the outer layer area are staggered one by one; the 18 metal composite nano dielectric pillars are not in contact with each other, and four shapes are formed between the 18 metal composite nano dielectric pillars 9 different cavities.

Further, the 18 metal composite nano dielectric columns include inner layer dielectric column I, inner layer dielectric column II, middle layer dielectric column and outer layer dielectric column; the inner layer area is rectangular, and the inner layer dielectric column I has 4, which are respectively arranged on the four vertices of the inner layer area, there are 2 of the inner layer dielectric columns II, which are respectively arranged on the midpoints of the two long sides of the inner layer area, and the inner layer The outer diameter of the dielectric column I is larger than that of the inner layer dielectric column II; the middle layer area is circular, and there are 6 middle layer dielectric columns, which are evenly distributed on the boundary of the middle layer area; the outer layer area is circular There are six outer layer dielectric columns, which are evenly distributed on the boundary of the outer layer region.

Further, the radius of the middle layer region is 208.75nm, the radius of the outer layer region is 257nm, the radius of the inner layer dielectric column I is 60nm, the center of the inner layer dielectric column I and the inner layer The distance between the center points of the region is 120.8 nm, the radius of the inner layer dielectric column II is 43.9 nm, the radius of the middle layer dielectric column is 60 nm, and the radius of the outer layer dielectric column is 67.5 nm.

Further, the thickness of the metal coating of the metal composite nano-dielectric column is 14-30 nm.

Further, the material of the metal coating of the metal composite nano-media column is gold or silver.

Furthermore, the relative permittivity of the innermost dielectric core of the metal composite nano-dielectric column ranges from 3.9 to 11.5.

Further, the material of the innermost dielectric core of the metal composite nano dielectric column is silicon or silicon dioxide.

Further, the relative magnetic permeability of the metal composite nano-media pillars is 1.

Further, the metal composite nano-media column is placed in an air environment.

Compared with the prior art, the beneficial effects of the present utility model are:

(1) Compared with the common electromagnetic resonator, the plasmon wave resonator composed of the metal composite nano-dielectric pillars of the present invention can pass through the gaps between the dielectric pillars to excite resonance from the outside.

(2) Compared with the single resonance mode of the traditional electromagnetic resonance cavity, the resonance cavity structure of the present invention can realize the diversified resonance mechanism for the incident electromagnetic waves of various frequencies, and the plasma waves excited by different frequencies are formed in different cavities. Different forms of resonance.

(3) The geometric size of the electromagnetic resonance cavity of the common resonance cavity determines the resonance frequency, and the metal composite nano-dielectric column of the present utility model can effectively change the resonance frequency of the plasma wave by changing the thickness of the metal layer, and the plasma wave The resonance space is not only the geometric space enclosed by the metal, but also includes the interface part of the space.

(4) The resonant cavity structure of the present invention can excite resonant plasma waves for incident waves of different frequencies by changing the materials of the innermost dielectric core and the outer metal coating.

Description of drawings

1 is a schematic diagram of multiple regions and multiple metal composite nano-dielectric pillars of the multiple resonant cavity of the present invention;

In the figure: 1, inner layer dielectric column I; 2, inner layer dielectric column II; 3, middle layer dielectric column; 4, outer layer dielectric column.

2 is a schematic diagram of the arrangement of the three-layer metal composite nano-dielectric column of the present invention;

In the figure: 101, the first inner layer dielectric column I; 102, the second inner layer dielectric column I; 103, the third inner layer dielectric column I; 104, the fourth inner layer dielectric column I; 201, the first inner layer dielectric Column II; 202, the second inner layer dielectric column II; 301, the first intermediate layer dielectric column; 302, the second intermediate layer dielectric column; 303, the third intermediate layer dielectric column; 304; the fourth intermediate layer dielectric column; 305, the fifth intermediate layer Dielectric column; 306, the sixth medium layer medium column; 401, the first outer layer medium column; 402, the second outer layer medium column; 403, the third outer layer medium column; 404, the fourth outer layer medium column; 405, the first Five outer layer dielectric columns; 406, sixth outer layer dielectric columns.

FIG. 3 is a schematic diagram of the absorption cross-section of an external plane wave with an incident angle of 0°, and all three-layer metal composite nano-dielectric columns are 18 nm thick silver coatings.

Fig. 4 is the near magnetic field distribution diagram of six peaks of absorption cross section in Fig. 3;

Among them, a is the incident frequency f(a)=9.261×10 ¹³ Hz, b is the incident frequency f(b)=1.347×10 ¹⁴ Hz, c is the incident frequency f(c)=1.563×10 ¹⁴ Hz, and d is the incident frequency The frequency f(d)=1.682×10 ¹⁴ Hz, e is the incident frequency f(e)=1.779×10 ¹⁴ Hz, and f is the plasmon resonance mode when the incident frequency f(f)=2.152×10 ¹⁴ Hz.

5 is a schematic diagram of the absorption cross-section of the three-layer metal composite nano-dielectric column obtained by changing the thickness (14 nm, 18 nm, 30 nm) of the metal-coated silver.

Figure 6 is a near-field image corresponding to six peaks when the thickness of the metal layer is 30 nm;

Among them, a is the magnetic field distribution at the incident frequency f(a)=0.9583×10 ¹⁴ Hz corresponding to the first peak, and b is the magnetic field distribution at the incident frequency f(b)=1.422×10 ¹⁴ Hz corresponding to the second peak , c is the magnetic field distribution diagram corresponding to the incident frequency of the third peak at f(c)=1.706×10 ¹⁴ Hz, d is the magnetic field distribution diagram corresponding to the incident frequency f(d)=1.851×10 ¹⁴ Hz of the fourth peak, e is the magnetic field distribution at the incident frequency f(e)=1.983×10 ¹⁴ Hz corresponding to the fifth peak, and f is the magnetic field distribution at the incident frequency f(f)=2.381×10 ¹⁴ Hz corresponding to the sixth peak.

FIG. 7 is an absorption cross-sectional view obtained when the innermost core dielectric material is silicon and silicon dioxide, respectively.

8 is an absorption cross-sectional view obtained when the metal coating materials are gold and silver, respectively.

Detailed ways

The present utility model will be further described below with reference to specific embodiments.

As shown in Figures 1-8, the multiple resonant cavity based on a plurality of metal composite nano-dielectric columns includes 18 metal composite nano-dielectric columns. The inner layer dielectric column I1, the inner layer dielectric column II2, the middle layer dielectric column 3 and the outer layer dielectric column 4 are respectively arranged on the boundary of the inner layer area, the middle layer area and the outer layer area. The area and the outer area are circular, and the center points of the inner area, the middle area and the outer area coincide.

Among them: the first inner layer dielectric column I101, the second inner layer dielectric column I102, the third inner layer dielectric column I103 and the fourth inner layer dielectric column I104 are located on the four vertices of the inner layer area; the first inner layer dielectric column II201 and the second inner layer dielectric column II 202 are respectively located at the midpoints of the two long sides of the inner layer region. The first middle layer dielectric column 301 , the second middle layer dielectric column 302 , the third middle layer dielectric column 303 , the fourth middle layer dielectric column 304 , the fifth middle layer dielectric column 305 and the sixth middle layer dielectric column 306 are uniformly distributed on the boundary of the middle layer region. The first outer dielectric column 401 , the second outer dielectric column 402 , the third outer dielectric column 403 , the fourth outer dielectric column 404 , the fifth outer dielectric column 405 and the sixth outer dielectric column 406 are evenly distributed in the outer layer. on the boundary of the layer region. The middle-layer dielectric columns 3 and the outer-layer dielectric columns 4 are staggered one by one. The connection line between the center of the inner layer dielectric column I1 and the center point of the inner layer area and the connection line between the centers of the two inner layer dielectric columns II2 are at 60° or 120°. The second middle layer dielectric column 302 and the fifth middle layer dielectric The line connecting the center of the column 305 is perpendicular to the line connecting the centers of the first inner layer dielectric column II 201 and the second inner layer dielectric column II 202; the third outer layer dielectric column 403, the sixth outer layer dielectric column 406 and the first inner layer The dielectric column II 201 and the second inner layer dielectric column II 202 are located on the same straight line.

The 18 nanometer dielectric pillars are not in contact with each other but have gaps, and 9 cavities of different sizes are formed between them, including: two large cavities on the left and right (the first middle-layer dielectric pillar 301, the sixth outer Between the layer dielectric column 406, the sixth intermediate layer dielectric column 306, the fourth inner layer dielectric column I104, the first inner layer dielectric column II201, and the first inner layer dielectric column I101; the second inner layer dielectric column I102, the second inner layer between the dielectric column II 202, the third inner layer dielectric column I103, the fourth middle layer dielectric column 304, the third outer layer dielectric column 403, and the third middle layer dielectric column 303), and a cavity in the central area (the first inner layer dielectric column I101 , between the second inner layer dielectric column I102, the third inner layer dielectric column I103 and the fourth inner layer dielectric column I104, the first inner layer dielectric column II201, and the second inner layer dielectric column II202), the upper and lower two small triangles are empty Cavity (between the first inner layer dielectric column I101, the second inner layer dielectric column I102, and the second middle layer dielectric column 302; between the third inner layer dielectric column I103, the fourth inner layer dielectric column I104, and the fifth middle layer dielectric column 305 between) and the outermost four small cavities (between the first inner layer dielectric column I101, the first middle layer dielectric column 301, the first outer layer dielectric column 401, and the second middle layer dielectric column 302; the second middle layer dielectric column 302 , between the second outer dielectric column 402, the third intermediate dielectric column 303, and the second inner dielectric column I102; the third inner dielectric column I103, the fourth intermediate dielectric column 304, the fourth outer dielectric column 404, the Between five middle-layer dielectric columns 305; between the fourth inner-layer dielectric column I104, the fifth middle-layer dielectric column 305, the fifth outer-layer dielectric column 405, and the sixth middle-layer dielectric column 306).

The relative dielectric constant of the innermost dielectric core of the metal composite nano-dielectric column is 3.9 to 11.5, silicon or silicon dioxide can be used, the thickness of the metal coating is 14 nm to 30 nm, and the gold or silver coating can be used. Magnetic permeability μ=1. The relative permittivity of metal coatings can be calculated using the Drude-Lorentz dispersion model, the specific formula is:

Among them, ω is the angular frequency of light, ε _∞ is the relative permittivity when ω→∞; ω _p is the plasma frequency; Δ is the weight of the Lorentz term; Γ _L is the vibration spectrum width; Ω _L is the strength of the Lorentz harmonic oscillator; The subscript L denotes the Lorentz model; i is the imaginary unit.

Among them, the relevant parameters of silver are as follows: ω is the angular frequency of the incident light, ε _∞ = 2.4046, ω _P = 2π×2214.6×10 ¹² Hz, Δ=1.6604, Γ _L = 2π×620.7×10 ¹² Hz, Ω _L = 2π×1330.1×10 ¹² Hz, i is the imaginary unit, γ=4.8×2π×10 ¹² Hz; the relevant parameters of gold are as follows: ω is the angular frequency of light, ε _∞ =4.0903, ω _P =2π×2170.7×10 ¹² Hz, Δ=4.9603, Γ _L = 2π×849.1×10 ¹² Hz, Ω _L = 2π×1006.4×10 ¹² Hz, i is an imaginary unit, γ=17.4×2π×10 ¹² Hz.

The selected frequency of the above resonator is 5.0×10 ¹³ Hz～2.5×10 ¹⁴ Hz. The electromagnetic wave is incident from the left boundary (including but not limited to plane waves), and the incident angle θ=0° (the angle of the incident wave can be any value, not limited to 0° , in the calculation, for the sake of convenience, the incident angle of 0° is taken), see Figure 2 for details (the arrow is the incident plane wave). For the metal composite nano-dielectric column with coating, the whole area is divided into three areas, area 1 is the free space area outside the three-layer metal composite nano-dielectric column, area 2 is the metal coating area, and area 3 is the inner core area of the dielectric column . Taking the xoy coordinate system as the global coordinate system, assuming that a TE plane wave is incident, Assumed angle of incidence According to the characteristics of cylindrical scattering, the incident wave H _z is written in the form of cylindrical wave Assuming that (ρ _j , φ _j ) represent the local coordinate system of the j-order metal composite nanodielectric pillars, (Φ ₀ , Φ _M , Φ _D ) and (Ψ ₀ and Ψ _M ) are defined as the incident cylindrical waves in the respective regions and scattered waves, where Φ represents the Bessel function and Ψ represents the Hankel function. From Maxwell's equation, Graf addition theorem and boundary conditions, it can be deduced that the outer free space ρ _j >r ₁ , the middle metal layer r ₂ <ρ _j <r ₁ , the magnetic field component at the innermost dielectric core ρ _j <r ₂ | The expression for Hz| is:

in, is the amplitude coefficient of the incident wave represented by the cylindrical Fourier series expansion, where is the angle of incidence; the left and right parts of equations (3) to (4) represent the incident wave and the scattered wave respectively, namely (Φ ₀ , Φ _M , Φ _D ) represent the inward propagating wave, (Ψ ₀ and Ψ _M ) represents the outward scattered wave, and the specific expression is as follows:

where J _m is a Bessel function of order m, is a Hankel function of the first kind of order m;

In Equation (5), G _j represents the mutual conversion of different coordinate systems, and the subscript j represents the transformation of the scattering field of other cylinders to the j object, which is in a j-order scattering field, G _i and D _j are the same; Equation (5) σ _q,j and α _q in are the transformation factors of the addition theorem, and the expressions are as follows:

A _p = -T ⁽¹⁾ k _p (p=2,3,...,N) (12)

D _j =[e ^in(j-1)θ δ _nn′ ] (14)

Among them, Λ _p , A _p , k _p are all transformation factors obtained using the Graf addition theorem, I is an identity matrix, δ _m is the Kronecker function, k ₀ is the wavenumber of free space, is the wavenumber of the metal layer, is the wavenumber of the medium core, and b is the amplitude vector of the incident wave; based on the local coordinate system (ρ, φ), the following coordinate transformation between cylindrical coordinates and plane coordinates is performed:

ζ _p = π/2-(p-1)θ/2 (15)

d _p = 2Rsin[(p-1)θ/2] (16)

In equations (2) to (5), T ⁽¹⁾ , T ⁽²⁾ , T ⁽³⁾ and T ⁽⁴⁾ are the transformation matrices of the fields in the two regions, representing the addition theorem of transformation matrices, and all is a diagonal matrix, the expression is as follows:

T ⁽¹⁾ = R _fm + F _fm · R _md · (IR _mf · R _md ) ^-1 · F _mf (18)

T ⁽²⁾ = (IR _mf · R _md ) ^-1 · F _mf (19)

T ⁽³⁾ = R _md · (IR _mf · R _md ) ^-1 · F _mf (20)

T ⁽⁴⁾ = F _dm · (IR _mf · R _md ) ^-1 · F _mf (21)

where R _ij and F _ij (i, j=f, m, d) are diagonal matrices representing the reflected and transmitted cylindrical waves from the “j” area to the “i” area, and the indices f, m, d represent the free Space, metal layer, and dielectric core; R _fm and F _fm represent the reflection and transmission matrices from the metal layer interface to the free space, R _md represent the reflection matrix from the dielectric core to the metal interface, R _mf and F _mf represent the reflection matrix from the outer layer The reflection and transmission matrices of the free space to the intermediate metal layer interface.

In order to quantitatively study the optical properties of the metal-coated nano-cylindrical structures, the far-field properties of the metal composite nano-cylindrical structures were explored by numerical analysis of the absorption cross-section σ _abs and the scattering cross-section σ _sca .

In order to model multiple metal composite nanodielectric pillar structures, a local coordinate system will be used (i=1,2....) The formulas expressing the scattered field are converted into the global coordinate system The scattered field formula is expressed in . Taking two metal composite nanopillars as an example, using the transformation matrix β ₀₁ , β ₀₂ , the local coordinate system Ψ _0,1 in and Converting Ψ _0,2 in Ψ 0 to Ψ ₀ , the expression formula of the external scattered field can be obtained:

in:

β ₀₁ (m,n)=(-1) ^mn J _mn (k ₀ d/2) (24)

β ₀₂ (m,n)=J _mn (k ₀ d/2) (25)

in Represents the scattering amplitude coefficients of two metal composite nanocylindrical structures.

The scattering and absorption cross sections of the two metal composite nanocylindrical structures can be deduced, and the specific expressions are as follows:

In the formula, The (m, n)th element of the scattering amplitude coefficient A in formula (27), P _n represents the amplitude coefficient of the incident plane wave.

Example 1

1 and 2, in this embodiment, the radius of the middle layer region is 208.75nm, the radius of the outer layer region is 257nm; the radius of the inner layer dielectric column I1 is 60nm, the distance between the center of the circle and the center point of the inner layer region The radius of the inner layer dielectric column II2 is 43.9 nm; the radius of the middle layer dielectric column 3 is 60 nm; the radius of the outer layer dielectric column 4 is 67.5 nm.

The metal composite nano-dielectric column of the multi-resonant cavity in this embodiment is coated with silver, and the inner layer dielectric core has an ordinary silicon medium with a relative permittivity of 10 and a relative magnetic permeability of 1.

According to the size of the nanopillars, the electromagnetic wave with a frequency of 5.0× ¹⁰¹³ Hz～2.5× ¹⁰¹⁴ Hz is selected to be incident from the left boundary, and the incident angle θ=0°. The σ ^abs (absorptive cross section of the three-layer metal composite nano-dielectric column is obtained by numerical solution) ), from the schematic diagram of the absorption cross-section shown in Figure 3, it can be clearly seen that there are 6 peaks, the peaks represent that the energy of the incident electromagnetic wave will cause the resonance of the plasma wave, resulting in coupling absorption, resulting in the reduction of the reflected wave energy. Absorption peaks appear on the cross section. According to the 6 peaks, the distribution of the near magnetic field _Hz corresponding to the 6 resonance peaks is shown in Fig. 4. It can be clearly seen that the 6 resonance peaks correspond to 6 different resonance modes.

The first resonance mode is shown in Fig. 4(a), and the incident frequency is 9.261×10 ¹³ Hz. At this frequency, the magnetic field is mainly distributed in the first inner layer dielectric column I101, the second inner layer dielectric column I102, the third inner layer dielectric column I103, the fourth inner layer dielectric column I104, the first inner layer dielectric column II201 and the second inner layer dielectric column I104. The central area surrounded by the inner layer dielectric column II 202 forms a strong resonance.

The second resonance mode is shown in Fig. 4(b), and the incident frequency is 1.347×10 ¹⁴ Hz. The excited plasma waves are generated in the first intermediate layer dielectric column 301, the sixth outer layer dielectric column 406, the sixth intermediate layer dielectric column 306, the fourth inner layer dielectric column I104, the first inner layer dielectric column II 201 and the first inner layer dielectric column I101. and the second inner layer dielectric column I102, the second inner layer dielectric column II 202, the third inner layer dielectric column I103, the fourth middle layer dielectric column 304, the third outer layer dielectric column 403 and the third middle layer dielectric column 303 are respectively surrounded by Strong resonances are formed in the two larger cavities on the left and right. In the two resonant cavities, the resonant plasma waves have opposite phases.

The third resonance mode is shown in Fig. 4(c), and the incident frequency is 1.563×10 ¹⁴ Hz. At this frequency, the plasma is concentrated in the first inner layer dielectric column I101, the second inner layer dielectric column I102, the second middle layer dielectric column 302 and the third inner layer dielectric column except for the same area as in FIG. 4(b). I103, the fourth inner layer dielectric column I104 and the fifth middle layer dielectric column 305 are respectively surrounded by two small triangle areas, and the resonant plasma wave has the same phase in the left and right resonant cavities, and the upper and lower cavities have the same phase, and The phase of the plasma wave is opposite to that of the left and right cavities.

The fourth resonance mode is shown in Fig. 4(d), and the incident frequency is 1.682×10 ¹⁴ Hz. The plasma is mainly concentrated in the central cavity (same as Fig. 4(a)) and the first inner layer dielectric column I101, the first middle layer dielectric column 301, the first outer layer dielectric column 401 and the second middle layer dielectric column 302, the second Intermediate dielectric column 302, second outer dielectric column 402, third intermediate dielectric column 303, second inner dielectric column I102, third inner dielectric column I103, fourth intermediate dielectric column 304, fourth outer dielectric column 404 and the fifth middle-layer dielectric column 305, the fourth inner-layer dielectric column I104, the fifth middle-layer dielectric column 305, the fifth outer-layer dielectric column 405 and the sixth middle-layer dielectric column 306 are respectively enclosed in the outermost four small cavities. , and the phase of the resonant plasma wave in the central region is opposite to the phase of the plasma wave in the outer four small cavity regions.

The fifth resonance mode is shown in Fig. 4(e), and the incident frequency is 1.779×10 ¹⁴ Hz. At this time, the plasma wave only formed resonance in the outermost four small cavities, and the plasma waves in the left and right small cavities were opposite in phase.

The sixth resonance mode is shown in Fig. 4(f) with an incident frequency of 2.152×10 ¹⁴ Hz. At this time, the frequency of the incident wave is relatively high, resulting in strong resonant plasma waves in the outermost four small cavities, the upper and lower two triangular cavities, and the central area. The resonant regions are in opposite phase.

Example 2

The arrangement and parameters of the three-layer metal composite nano-dielectric column in this example are basically the same as those in Example 1, and the difference lies in the thickness of the metal coating.

The thickness of the silver coating is taken as 14nm, 18nm and 30nm respectively, and the selected frequency is from 5×10 ¹³ Hz to 2.5×10 ¹⁴ Hz plane wave is incident from the left boundary, and the incident angle θ=0°, and the three thicknesses shown in Figure 5 are obtained. Corresponding absorption cross-sectional diagrams, the thickness of the silver layer is 14 nm with solid lines, the thickness of 18 nm is shown with dotted lines, and the thickness of 30 nm is shown with dotted lines. It can be seen that as the thickness of the metal layer increases, the excitation frequency of the absorption cross section (ACS) resonance peak will increase, and the peak displayed on the absorption cross section will shift to the right, and the higher the frequency, the more obvious the right shift of the peak. Figure 6 shows the near-field images corresponding to the six peaks when the thickness of the metal layer is 30 nm. It can be seen from Figure 6 that although the thickness of the metal layer changes, the geometry of the cavity structure enclosed by the metal composite nano-cylinders does not change, so the The six resonance peaks correspond to the same six plasmonic wave resonance modes, which are consistent with Fig. 4, but the corresponding frequencies are higher. It can also be known that the plasmonic wave resonance excited by the incident electromagnetic wave in the multilayer composite dielectric column cavity is similar to Unlike general electromagnetic wave resonance, there is no fixed resonance mode or frequency.

Example 3

The arrangement and parameters of the three-layer metal composite nano-media columns in this embodiment are basically the same as those in Embodiment 1, and the difference lies in the material of the innermost core medium.

Using silicon with a relative permittivity of 11.5 and silicon dioxide with a relative permittivity of 3.9, respectively, the absorption cross-sectional view of the three-layer metal composite nano-dielectric column shown in Figure 7 is obtained, in which silicon is represented by a solid line, and silicon dioxide is Dotted line indicates. It can be seen from Figure 7 that since the geometrical structures of the multiple metal nanocomposite pillars are the same, the number and structure of the cavities formed in the nanometer dielectric pillars are also the same. Although the dielectric constants of the inner layer materials of the dielectric pillars are different, there are still corresponding The six absorption peaks of , indicating that the change of the dielectric constant of the dielectric column does not change the resonance law of the plasma wave in the composite structure. But at the same time, it can be seen that when the relative permittivity decreases, the resonance peak formed by the excited plasma wave obviously shifts to the right. The higher the incident frequency of the resonance peak generated by the plasma wave formed on the surface, the different plasma resonances can be obtained by changing the material of the innermost core medium.

Example 4

The arrangement and parameters of the three-layer metal composite nano-dielectric column in this example are basically the same as those in Example 1, and the difference lies in the material of the outer metal coating.

Two different coatings of silver and gold with a thickness of 18 nm are respectively used, both of which are described by the Drude-Lorentz dispersion model, and the specific calculation is determined by the formula (1). At this time, the absorption cross-section of the corresponding gold and silver-coated composite nano-dielectric pillars (see Figure 8) can be analyzed, and it can be found that under the same thickness of 18 nm, the electromagnetic absorption cross-section of silver is significantly larger than that of gold. Especially in the high-frequency component, the absorption cross section of gold is significantly reduced, and the resonance frequency of high-frequency plasma disappears, that is to say, the excitation intensity of gold in the composite nano-column cavity is weakened at high frequency, and no obvious Resonance, indicating that silver is more sensitive to high-frequency electromagnetic wave induction than gold. At the same time, it can be seen that the resonance frequency of the plasmon wave formed by the gold nanocomposite pillars is slightly lower than that of silver in the same mode, relative to silver.

Claims (9)

1. a multiple resonant cavity based on a plurality of metal composite nano-dielectric columns, is characterized in that, comprises 18 metal composite nano-dielectric columns respectively arranged in the inner layer region, the middle layer region and the outer layer region, the inner layer region , the center points of the middle layer area and the outer layer area are coincident; 6 metal composite nanometer dielectric pillars of the 18 metal composite nanometer dielectric pillars are arranged in a rectangle in the inner layer area, and 6 of the 18 metal composite nanometer dielectric pillars are arranged in a rectangle. The other 6 metal composite nano dielectric columns are uniformly arranged in a circle in the middle layer area, and the remaining 6 metal composite nano dielectric columns among the 18 metal composite nano dielectric columns are uniformly arranged in a circle in the outer layer area, and the middle layer The metal composite nanomedia dielectric pillars in the region and the metal composite nanomedia dielectric pillars in the outer region are arranged in a staggered manner; the 18 metal composite nano dielectric pillars do not contact each other, and the 18 metal composite nano dielectric pillars are not in contact with each other. Nine cavities with four different shapes are formed between them. 2 . The multiple resonant cavity according to claim 1 , wherein the 18 metal composite nano-dielectric pillars comprise inner-layer dielectric pillars I (1), inner-layer dielectric pillars II (2), and middle-layer dielectric pillars (3 . 3 . ) and an outer layer dielectric column (4); the inner layer region is rectangular, and there are four inner layer dielectric columns I (1), which are respectively arranged on the four vertices of the inner layer region. There are two dielectric columns II (2), which are respectively arranged at the midpoints of the two long sides of the inner layer region, and the outer diameter of the inner layer dielectric column I (1) is larger than that of the inner layer dielectric column II ( 2); the middle layer area is circular, and there are 6 middle layer dielectric columns (3), which are evenly distributed on the boundary of the middle layer area; the outer layer area is circular, and the outer layer dielectric columns ( 4) There are 6, which are evenly distributed on the boundary of the outer layer area. 3. The multiple resonant cavity according to claim 2, wherein the radius of the middle layer region is 208.75nm, the radius of the outer layer region is 257nm, and the radius of the inner layer dielectric column I(1) is 60 nm, the distance between the center of the inner layer dielectric column I (1) and the center point of the inner layer region is 120.8 nm, the radius of the inner layer dielectric column II (2) is 43.9 nm, and the middle layer dielectric column is 43.9 nm. The radius of (3) is 60 nm, and the radius of the outer layer dielectric column (4) is 67.5 nm. 4 . The multiple resonant cavity according to claim 1 or 3 , wherein the thickness of the metal coating of the metal composite nano-dielectric column is 14-30 nm. 5 . 5 . The multiple resonant cavity according to claim 1 or 3 , wherein the metal coating of the metal composite nano-dielectric column is made of gold or silver. 6 . 6 . The multiple resonant cavity according to claim 1 or 3 , wherein the relative permittivity of the innermost dielectric core of the metal composite nano-dielectric column ranges from 3.9 to 11.5. 7 . 7 . The multiple resonant cavity according to claim 1 or 3 , wherein the material of the innermost dielectric core of the metal composite nano-dielectric column is silicon or silicon dioxide. 8 . 8 . The multiple resonant cavity according to claim 1 or 3 , wherein the relative magnetic permeability of the metal composite nano-dielectric column is 1. 9 . 9 . The multiple resonant cavity according to claim 1 or 3 , wherein the metal composite nano-dielectric column is placed in an air environment. 10 .