A dual-band surface plasmon resonator

Abstract

The invention relates to a meta-material resonant cavity field, and provides an artificial cavity structure realizing local surface plasma resonance in a low frequency band like the microwave. The dual-frequency-band surface plasma resonant cavity can enhance infiltration of electromagnetic wave on the cavity wall through opening grooves having constant cycles on the inner wall of the cavity, wherein the grooves are filled with medium materials and the dielectric constant of the material is even. The grooves of the resonance cavity has two depth modes and are distributed on the circumference direction in a staggered manner, so that the single structure can realize the resonance in multiple frequency-bands and can realize the local surface plasma resonance.

Description

technical field

[0001] The invention relates to a resonant cavity structure, in particular to a resonant cavity based on artificial localized surface plasmon resonance. Background technique

[0002] Localized Surface Plasmon (LSP) refers to a localized electromagnetic wave mode bound on the metal surface, which is caused by the interaction between light and free electrons on the metal surface, and it is confined near the interface between the metal and the medium , can form an enhanced near field. Because the plasma frequency of metal is generally in the ultraviolet band, in the microwave band, electromagnetic waves are difficult to penetrate, and the metal approximately behaves as a perfect electric conductor (Perfect Electric Conductor, PEC). In these cases, metal surfaces cannot excite LSP waves. In recent years, in order to introduce the concept of localized surface plasmons to low frequencies (far infrared, terahertz and microwave millimeter wave frequencies), Profess...

Examples

Embodiment 1

[0017] As shown in Figure 1(a), the basic structure of the resonant cavity is a metal cylinder with a certain thickness that is closed at both ends (both ends are closed with a circular metal plate that matches the cross-sectional area of ​​the metal cylinder). The inner diameter of the cross-section is r, and the inner wall is provided with two kinds of axial grooves uniformly distributed along the circumference. The central angles corresponding to each groove are equal, and the cross-section is fan-shaped. The two axial grooves have different depths R 1 -r (deep groove) and R 2 -r (shallow groove), R 1 >R 2 , R 1 , R 2 represent the radii at the maximum radians of the two grooves respectively. Generally speaking, there is an approximate formula for the asymptotic frequency of the surface plasmon structure, f a =c / (4hn g ), where c is the speed of light, h=R 1 (2)-r is the depth of the groove, n g Represents the refractive index of the material in the trench, from whi...

Embodiment 2

[0019] Taking the resonant cavity shown in Figure 1(a) as an example, the radius r=1.33 mm, and the radius at the maximum radian of the groove is R 1 = 5 mm, R 2 =3.33 mm, different groove depths determine the different resonant frequencies of the structure. The dielectric constant of the filling dielectric material is equal to 25, and the filling of the dielectric material can reduce the resonant frequency of the resonant cavity. According to the equivalent medium theory, the more the number of periods is set, the better the effect, but the increase in the number of grooves will cause inconvenience in processing. Here we make a compromise by periodically distributing N=120 grooves along the circumferential direction, in which deep grooves and shallow grooves are respectively There are 60 of them, and they are staggered and evenly distributed.

[0020] According to the second embodiment, the electromagnetic simulation software can be used to obtain the dispersion curve as sh...

technical field

[0001] The invention relates to a resonant cavity structure, in particular to a resonant cavity based on artificial localized surface plasmon resonance. Background technique

[0002] Localized Surface Plasmon (LSP) refers to a localized electromagnetic wave mode bound on the metal surface, which is caused by the interaction between light and free electrons on the metal surface, and it is confined near the interface between the metal and the medium , can form an enhanced near field. Because the plasma frequency of metal is generally in the ultraviolet band, in the microwave band, electromagnetic waves are difficult to penetrate, and the metal approximately behaves as a perfect electric conductor (Perfect Electric Conductor, PEC). In these cases, metal surfaces cannot excite LSP waves. In recent years, in order to introduce the concept of localized surface plasmons to low frequencies (far infrared, terahertz and microwave millimeter wave frequencies), Profess...

Examples

Embodiment 1

[0017] As shown in Figure 1(a), the basic structure of the resonant cavity is a metal cylinder with a certain thickness that is closed at both ends (both ends are closed with a circular metal plate that matches the cross-sectional area of ​​the metal cylinder). The inner diameter of the cross-section is r, and the inner wall is provided with two kinds of axial grooves uniformly distributed along the circumference. The central angles corresponding to each groove are equal, and the cross-section is fan-shaped. The two axial grooves have different depths R 1 -r (deep groove) and R 2 -r (shallow groove), R 1 >R 2 , R 1 , R 2 represent the radii at the maximum radians of the two grooves respectively. Generally speaking, there is an approximate formula for the asymptotic frequency of the surface plasmon structure, f a =c / (4hn g ), where c is the speed of light, h=R 1 (2)-r is the depth of the groove, n g Represents the refractive index of the material in the trench, from whi...

Embodiment 2

[0019] Taking the resonant cavity shown in Figure 1(a) as an example, the radius r=1.33 mm, and the radius at the maximum radian of the groove is R 1 = 5 mm, R 2 =3.33 mm, different groove depths determine the different resonant frequencies of the structure. The dielectric constant of the filling dielectric material is equal to 25, and the filling of the dielectric material can reduce the resonant frequency of the resonant cavity. According to the equivalent medium theory, the more the number of periods is set, the better the effect, but the increase in the number of grooves will cause inconvenience in processing. Here we make a compromise by periodically distributing N=120 grooves along the circumferential direction, in which deep grooves and shallow grooves are respectively There are 60 of them, and they are staggered and evenly distributed.

[0020] According to the second embodiment, the electromagnetic simulation software can be used to obtain the dispersion curve as sh...

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