CN108732748A - Mostly band Meta Materials absorber design method based on enhancing high order resonance mould absorptivity - Google Patents

Abstract

The mostly band Meta Materials absorber design method based on enhancing high order resonance mould absorptivity that the invention discloses a kind of, is related to Meta Materials field.Mostly band Meta Materials absorber design method based on enhancing high order resonance mould absorptivity is applied in the Meta Materials absorber, and the Meta Materials absorber top layer includes a periodic micro structure, and the periodic micro structure is at least made of a pair of of basic structural unit；Reduce the spacing of at least a pair of of basic structural unit in the periodic micro structure of the Meta Materials absorber top layer.The present invention forms near-field coupling to achieve the purpose that improve the absorptivity of the high-order Plasmon Resonance pattern of the basic structural unit by reducing the spacing of at least a pair of of basic structural unit.

Description

Design method of multi-band metamaterial absorber based on enhanced high-order resonant mode absorptivity

technical field

The invention relates to the field of metamaterials, in particular to a method for designing a multi-band metamaterial absorber based on enhanced high-order resonant mode absorption rate.

Background technique

Metamaterials have special properties not found in nature, which can usually be manipulated by changing the nanostructure rather than the chemical composition. As a new type of metamaterial, the perfect absorber of metamaterials has been widely used in thermal radiators, biosensing, microbolometers and infrared detection in recent years because it can achieve an absorption rate of more than 90% in certain spectral ranges. application has attracted great attention. The structure of metamaterial absorbers usually studied is a three-layer sandwich structure of metal-dielectric-metal. The bottom is a metal film, the middle layer is a dielectric film, and the top is a periodic metal oscillator. The incident electromagnetic wave can cause the collective oscillation of electrons in the periodic metal oscillator, which is to excite the surface plasmon resonance mode. However, for metamaterial absorbers based on plasmon resonance in a sandwich structure, a vibrator usually has only one absorption band, and this absorption band comes from the fundamental mode. The single band problem greatly limits the application of metamaterial absorbers.

In order to solve the single-band problem, people usually combine oscillators of different sizes, and each size of oscillator can form an absorption band, so that multiple bands can be obtained through the combination of oscillators. This method of oscillator combination only utilizes the fundamental mode, so when there are many absorption bands, the corresponding periodic unit structure will be very complicated. In fact, in addition to the fundamental mode, the vibrator can also excite high-order resonance modes, but the absorption rate of the high-order resonance modes is very low, so the method of combining vibrators cannot use high-order modes.

Contents of the invention

In view of the above problems, a multi-band metamaterial absorber design method based on enhancing the high-order resonant mode absorptivity is provided, which aims to improve the high-order plasmon resonance mode absorptivity to design a multi-band absorber.

A method for designing a multi-band metamaterial absorber based on enhanced high-order resonant mode absorptivity, the top layer of the metamaterial absorber includes a periodic microstructure, and the periodic microstructure is at least composed of a pair of basic structural units;

reducing the distance between at least one pair of basic structural units in the periodic microstructure of the top layer of the metamaterial absorber.

Preferably, the distance between at least one pair of basic structural units after shrinking is between 5nm and 80nm.

Preferably, the metamaterial absorber includes:

The metal base layer, the dielectric film is deposited on the metal base layer, and the periodic microstructure is etched on the surface of the dielectric film.

Preferably, the periodic microstructure consists of a pair of basic structural units.

Preferably, the pair of basic structural units includes a rectangular ring and a circular ring, the circular ring is located in the rectangular ring, and the center of the circular ring coincides with the center of the rectangular ring.

Preferably, the metal base layer is made of silver film, the dielectric film is made of zinc sulfide film, and the periodic microstructure is made of silver material, or

The metal base layer is made of aluminum film, the dielectric film is made of zinc sulfide film, and the periodic microstructure is made of aluminum.

Preferably, the rectangular ring is a square ring;

The height of the metal base layer is 200nm;

The height of the dielectric film is 80nm, the length is 1000nm, and the width is 1000nm;

The ring height of the basic structural unit is 200nm, the inner diameter is 250nm, and the outer diameter is 460nm;

The height of the square ring is 200nm, the inner diameter is 600nm, and the outer diameter is 740nm;

The distance between the circular ring and the square ring is 70nm.

Preferably, the rectangular ring is a square ring;

The height of the metal base layer is 200nm;

The height of the dielectric film is 80nm, the length is 1000nm, and the width is 1000nm;

The ring height of the basic structural unit is 200nm, the inner diameter is 250nm, and the outer diameter is 460nm;

The height of the square ring is 200nm, the inner diameter is 560nm, and the outer diameter is 700nm;

The distance between the circular ring and the square ring is 50nm.

Preferably, the rectangular ring is a square ring;

The height of the metal base layer is 200nm;

The height of the dielectric film is 80nm, the length is 1000nm, and the width is 1000nm;

The ring height of the basic structural unit is 200nm, the inner diameter is 250nm, and the outer diameter is 460nm;

The height of the square ring is 200nm, the inner diameter is 520nm, and the outer diameter is 660nm;

The distance between the circular ring and the square ring is 30nm.

Preferably, the rectangular ring is a square ring;

The height of the metal base layer is 200nm;

The height of the dielectric film is 80nm, the length is 1000nm, and the width is 1000nm;

The ring height of the basic structural unit is 200nm, the inner diameter is 250nm, and the outer diameter is 460nm;

The height of the square ring is 200nm, the inner diameter is 480nm, and the outer diameter is 620nm;

The distance between the circular ring and the square ring is 10nm.

The beneficial effect of above-mentioned technical scheme:

In the technical solution, the near-field coupling is formed by reducing the distance between at least one pair of basic structural units, so as to achieve the purpose of improving the absorption rate of the high-order plasmon resonance mode of the basic structural unit.

Description of drawings

Fig. 1 is a perspective view of an embodiment of a metamaterial absorber of the present invention;

Figure 2 is a top view of the metamaterial absorber;

Fig. 3 is a schematic diagram of the enhancement of the absorption rate of the high-order plasmon resonance mode of the first embodiment when the distance between the circular ring and the square ring is reduced;

Figure 4 (a-d) is the electric field intensity distribution diagram of the high-order plasmon resonance mode of the first embodiment when the distance between the circular ring and the square ring is reduced in the present invention;

Fig. 5 is a graph of the absorption rate of the high-order plasmon resonance mode of the first embodiment;

Fig. 6 is a schematic diagram of the enhancement of the absorption rate of the high-order plasmon resonance mode of the second embodiment when the distance between the circular ring and the square ring is reduced;

Fig. 7 (a-d) is the electric field intensity distribution diagram of the high-order plasmon resonance mode of the second embodiment when the distance between the circular ring and the square ring is reduced in the present invention;

FIG. 8 is a graph of the absorption rate of the high-order plasmon resonance mode of the second embodiment.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

It should be noted that, in the case of no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but not as a limitation of the present invention.

As shown in Figure 1-2, a multi-band metamaterial absorber design method based on enhanced high-order resonance mode absorption rate, the top layer of the metamaterial absorber includes a periodic microstructure, and the periodic microstructure is at least composed of Composed of a pair of basic structural units;

reducing the distance between at least one pair of basic structural units in the periodic microstructure of the top layer of the metamaterial absorber.

Further, the distance between at least one pair of basic structural units after shrinking is between 5nm and 80nm. The basic structural unit is the metal vibrator.

In this embodiment, a strong near-field coupling is formed by reducing the distance between at least one pair of basic structural units so as to achieve the purpose of increasing the absorption rate of the high-order plasmon resonance mode of the basic structural units. Each basic structural unit corresponds to an absorption band of the base film. When the distance between a pair of basic structural units is reduced, a strong near-field coupling will be formed between the basic structural units, which can enhance the absorption rate of the high-order plasmon resonance mode , forming an additional higher-order absorption band. The higher-order absorption bands and the fundamental mode absorption bands together constitute the perfect absorber of multi-band metamaterials.

Preferably, the metamaterial absorber includes:

The metal base layer, the dielectric film is deposited on the metal base layer, and the periodic microstructure is etched on the surface of the dielectric film.

Preferably, the periodic microstructure consists of a pair of basic structural units.

As a first embodiment, the pair of basic structural units may be, but not limited to, a rectangular ring and a circular ring. When the basic structural unit includes a rectangular ring and a circular ring, the circular ring is located at the Inside, the center of the circular ring coincides with the center of the rectangular ring.

Further, the metal base layer is made of silver (Ag) film, the dielectric film is made of zinc sulfide (ZnS) film, and the periodic microstructure is made of silver (Ag).

Case 1: The rectangular ring is a square ring;

The height T3 _of the metal base layer is 200nm;

_The height T2 of the dielectric film is 80nm, the length P is 1000nm, and the width P is 1000nm;

_The ring height T1 _of the basic structural unit is 200nm, the inner diameter L1 is 250nm, and the outer diameter L2 is 460nm _;

The height of the square ring is 200nm, the inner diameter L3 is 600nm, the outer diameter L4 is 740nm, and the width W ₌ (L4 _- L3)/ _{2 =} 70nm;

The distance D between the circular ring and the square ring is (L ₃ -L ₂ )/2=70nm.

Case 2: The rectangular ring is a square ring;

The height T3 _of the metal base layer is 200nm;

_The height T2 of the dielectric film is 80nm, the length P of the dielectric film is 1000nm, and the width P is 1000nm;

_The ring height T1 _of the basic structural unit is 200nm, the inner diameter L1 is 250nm, and the outer diameter L2 is 460nm _;

The height of the square ring is 200nm, the inner diameter L3 is 560nm, the outer diameter L4 is 700nm, and the width W ₌ (L4 _- L3)/ _{2 =} 70nm;

The distance D between the circular ring and the square ring is (L ₃ -L ₂ )/2=50nm.

Case 3: The rectangular ring is a square ring;

The height T3 _of the metal base layer is 200nm;

_The height T2 of the dielectric film is 80nm, the length P of the dielectric film is 1000nm, and the width P is 1000nm;

_The ring height T1 _of the basic structural unit is 200nm, the inner diameter L1 is 250nm, and the outer diameter L2 is 460nm _;

The height of the square ring is 200nm, the inner diameter L3 is 520nm, the outer diameter L4 is 660nm, and the width W ₌ (L4 _- L3)/ _{2 =} 70nm;

The distance D between the circular ring and the square ring is (L ₃ -L ₂ )/2=30nm.

Case 4: The rectangular ring is a square ring;

The height T3 _of the metal base layer is 200nm;

_The height T2 of the dielectric film is 80nm, the length P of the dielectric film is 1000nm, and the width P is 1000nm;

The basic structural unit ring T1 has _a height of 200nm, an inner diameter L1 _of 250nm, and an outer diameter L2 of 460nm _;

The height of the square ring is 200nm, the inner diameter L3 is 480nm, the outer diameter L4 is 620nm, and the width W ₌ (L4 _- L3)/ _{2 =} 70nm;

The distance D between the circular ring and the square ring is (L ₃ −L ₂ )/2=10 nm.

Based on the above situations 1-4, that is, when the distance D between the ring and the square ring is reduced from 70nm to 50nm, 30nm, and 10nm, the spectral absorptivity of the metamaterial absorber is shown in Figure 3, and the electric field z direction of the absorption peak f3 The distribution of is shown in Fig. 4(ad). The absorption peak f ₁ corresponds to the fundamental plasmon resonance mode of the square ring, and f ₂ corresponds to the fundamental plasmon resonance mode of the ring, that is, the fundamental mode. The absorption peak f ₃ corresponds to the higher-order plasmon resonance mode of the square ring, that is, the higher-order mode. When the distance between the square ring and the ring is shortened, a strong near-field coupling is formed between the square ring and the ring, resulting in an increase in the maximum value of the electric field intensity in the z direction of the high-order plasmon resonance mode from 5.6 to 10, 16, 21, and the absorption of higher-order plasmon resonance modes also increased from 17.6% to 37.4%, 67.7%, and 95.3%.

In summary, as shown in Figure 5, when the distance between the square ring oscillator and the circular ring oscillator is reduced from 110nm to 80nm, the absorption rate of the high-order mode basically does not change at the beginning. When shrinking to 5nm, the absorptivity increases sharply with the shrinking pitch. In this embodiment, the method of in-field coupling of oscillators is used to increase the absorption rate of the high-order plasmon resonance mode from 17.6% to 95.3%, realizing the purpose of using three absorption bands generated by two oscillators.

As shown in Fig. 1-Fig. 2, as a second embodiment, the metal base layer can adopt aluminum (Al) film layer, the dielectric thin film adopts zinc sulfide (ZnS) thin film, and the periodic microstructure adopts aluminum (Al) material.

Case 1: The rectangular ring is a square ring;

The height T3 _of the metal base layer is 200nm;

_The height T2 of the dielectric film is 80nm, the length P is 1000nm, and the width P is 1000nm;

_The ring height T1 _of the basic structural unit is 200nm, the inner diameter L1 is 250nm, and the outer diameter L2 is 460nm _;

The height of the square ring is 200nm, the inner diameter L3 is 600nm, the outer diameter L4 is 740nm, and the width W ₌ (L4 _- L3)/ _{2 =} 70nm;

The distance D between the circular ring and the square ring is (L ₃ -L ₂ )/2=70nm.

Case 2: The rectangular ring is a square ring;

The height T3 _of the metal base layer is 200nm;

_The height T2 of the dielectric film is 80nm, the length P of the dielectric film is 1000nm, and the width P is 1000nm;

_The ring height T1 _of the basic structural unit is 200nm, the inner diameter L1 is 250nm, and the outer diameter L2 is 460nm _;

The height of the square ring is 200nm, the inner diameter L3 is 560nm, the outer diameter L4 is 700nm, and the width W ₌ (L4 _- L3)/ _{2 =} 70nm;

The distance D between the circular ring and the square ring is (L ₃ -L ₂ )/2=50nm.

Case 3: The rectangular ring is a square ring;

The height T3 _of the metal base layer is 200nm;

_The height T2 of the dielectric film is 80nm, the length P of the dielectric film is 1000nm, and the width P is 1000nm;

_The ring height T1 _of the basic structural unit is 200nm, the inner diameter L1 is 250nm, and the outer diameter L2 is 460nm _;

The height of the square ring is 200nm, the inner diameter L3 is 520nm, the outer diameter L4 is 660nm, and the width W ₌ (L4 _- L3)/ _{2 =} 70nm;

The distance D between the circular ring and the square ring is (L ₃ -L ₂ )/2=30nm.

Case 4: The rectangular ring is a square ring;

The height T3 _of the metal base layer is 200nm;

_The height T2 of the dielectric film is 80nm, the length P of the dielectric film is 1000nm, and the width P is 1000nm;

The basic structural unit ring T1 has _a height of 200nm, an inner diameter L1 _of 250nm, and an outer diameter L2 of 460nm _;

The height of the square ring is 200nm, the inner diameter L3 is 480nm, the outer diameter L4 is 620nm, and the width W ₌ (L4 _- L3)/ _{2 =} 70nm;

The distance D between the circular ring and the square ring is (L ₃ −L ₂ )/2=10 nm.

For the above cases 1-4, that is, when the distance D between the ring and the square ring is reduced from 70nm to 50nm, 30nm, and 10nm, the spectral absorptivity of the metamaterial absorber is shown in Figure 6, and the electric field z direction of the absorption peak f ₃ The distribution of is shown in Fig. 7(ad). _The absorption peaks f1 and _f2 correspond to the fundamental plasmon resonance modes of the square ring and the ring, that is, the fundamental mode, respectively. The absorption peak _f3 corresponds to the higher-order plasmon resonance mode of the square ring. When the distance between the square ring and the ring is shortened, a strong near-field coupling is formed between the square ring and the ring, resulting in the maximum value of the electric field intensity in the z direction of the high-order plasmon resonance mode increasing from 3.3 to 6.5, 10.3 to 14.3, while the absorption of higher-order plasmon resonance modes was also successfully increased from 14% to 33%, and from 60% to 89%. Therefore, in this embodiment, the method of coupling the vibrator into the field is used to successfully increase the absorption rate of the high-order plasmon resonance mode from 14% to 89%, and successfully utilize the three absorption bands realized by two vibrators.

As shown in Figure 8, when the distance between the square ring oscillator and the circular ring oscillator is reduced from 110nm to 80nm, the absorption rate of the high-order mode basically does not change at the beginning. When the distance between the square ring oscillator and the circular ring oscillator is reduced from 80nm to 5nm, The absorptivity increases sharply with the shrinking of the spacing.

Further, for example and not limitation, the dielectric film may be but not limited to silicon dioxide (SiO2), silicon (Si), aluminum oxide (Al2O3), zinc sulfide (ZnS) and the like.

The metal base layer can be, but is not limited to, gold, silver, aluminum, copper, and the like.

Periodic microstructures can be, but are not limited to, gold, silver, aluminum, copper, and the like.

The paired metal oscillators in the top periodic microstructure can be but not limited to concentric square rings and circular rings.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the implementation and protection scope of the present invention. For those skilled in the art, they should be able to realize that all equivalents made by using the description and illustrations of the present invention The solutions obtained by replacement and obvious changes shall all be included in the protection scope of the present invention.

Claims (10)

1. A method for enhancing high-order resonance mode absorptivity to design multi-band metamaterial absorbers, the metamaterial absorber top layer includes a periodic microstructure, and the periodic microstructure is at least made up of a pair of basic structural units; It is characterized by: reducing the distance between at least one pair of basic structural units in the periodic microstructure of the top layer of the metamaterial absorber. 2. The method for designing a multi-band metamaterial absorber for enhancing high-order resonance mode absorptivity according to claim 1, wherein the distance between at least one pair of basic structural units is between 5nm and 80nm after shrinking. 3. the method for designing multi-band metamaterial absorbers according to claim 1, wherein the metamaterial absorbers comprise: The metal base layer, the dielectric film is deposited on the metal base layer, and the periodic microstructure is etched on the surface of the dielectric film. 4. The method for designing a multi-band metamaterial absorber for enhancing high-order resonance mode absorptivity according to claim 1 or 3, wherein the periodic microstructure is composed of a pair of basic structural units. 5. the method for designing multi-band metamaterial absorbers with enhanced high-order resonance mode absorptivity according to claim 4, is characterized in that, the pair of basic structural units comprises a rectangular ring and a circular ring, and the circular ring Located in the rectangular ring, the center of the circular ring coincides with the center of the rectangular ring. 6. the method for designing multi-band metamaterial absorbers according to the enhanced high-order resonance mode absorptivity according to claim 5, is characterized in that, described metal base layer adopts silver film layer, and described dielectric thin film adopts zinc sulfide thin film, so The periodic microstructure is made of silver material, or The metal base layer is made of aluminum film, the dielectric film is made of zinc sulfide film, and the periodic microstructure is made of aluminum. 7. the method for designing multi-band metamaterial absorbers according to claim 6, wherein the rectangular ring is a square ring; The length of the dielectric film is 1000nm, and the width is 1000nm; The ring height of the basic structural unit is 200nm, the inner diameter is 250nm, and the outer diameter is 460nm; The height of the square ring is 200nm, the inner diameter is 600nm, and the outer diameter is 740nm; The distance between the circular ring and the square ring is 70nm. 8. The method for designing multi-band metamaterial absorbers according to claim 6, wherein the rectangular ring is a square ring; The height of the metal base layer is 200nm; The height of the dielectric film is 80nm, the length is 1000nm, and the width is 1000nm; The ring height of the basic structural unit is 200nm, the inner diameter is 250nm, and the outer diameter is 460nm; The height of the square ring is 200nm, the inner diameter is 560nm, and the outer diameter is 700nm; The distance between the circular ring and the square ring is 50nm. 9. The method for designing multi-band metamaterial absorbers according to claim 6, wherein the rectangular ring is a square ring; The height of the metal base layer is 200nm; The height of the dielectric film is 80nm, the length is 1000nm, and the width is 1000nm; The ring height of the basic structural unit is 200nm, the inner diameter is 250nm, and the outer diameter is 460nm; The height of the square ring is 200nm, the inner diameter is 520nm, and the outer diameter is 660nm; The distance between the circular ring and the square ring is 30nm. 10. The method for designing multi-band metamaterial absorbers according to claim 6, wherein the rectangular ring is a square ring; The height of the metal base layer is 200nm; The height of the dielectric film is 80nm, the length is 1000nm, and the width is 1000nm; The ring height of the basic structural unit is 200nm, the inner diameter is 250nm, and the outer diameter is 460nm; The height of the square ring is 200nm, the inner diameter is 480nm, and the outer diameter is 620nm; The distance between the circular ring and the square ring is 10nm.