An equivalent artificial surface plasmon based fast-slow wave mode composite waveguide

Abstract

The application discloses a fast-slow wave mode composite waveguide based on equivalent artificial surface plasmons, which comprises a first conducting block and a second conducting block which are stacked and connected seamlessly at the end face edge; the input end face and the output end face of the first conducting block are used as the signal input end and the output end under the fast wave mode respectively; and the input end face and the output end face of the second conducting block are used as the signal input end and the output end under the slow wave mode respectively. The application has small size, low loss, and can support fast wave and slow wave signals simultaneously within a wide band, which is very meaningful for improving signal capacity in communication transmission.

Description

Technical Field

[0001] This invention belongs to the field of waveguide structure technology, specifically relating to a fast and slow wave mode composite waveguide based on equivalent artificial surface plasmons. Background Technology

[0002] Surface plasmon polaritons (SPPs) are nonradiative electromagnetic modes formed by the coupling of free electrons and incident photons on a metal surface, localized between the metal and dielectric interfaces. When an electromagnetic wave is incident, surface electromagnetic wave oscillations are generated at the interface, with the amplitude being strongest at the interface and exhibiting exponential decay within the metal and dielectric after leaving the interface. The high degree of confinement of electromagnetic fields by SPPs can overcome the diffraction limit, achieving subwavelength confinement.

[0003] To achieve SPP phenomena similar to those in the optical band at microwave or terahertz frequencies, Pendry et al. proposed the concept of Spoof Surface Plasmon Polaritons (SSPPs) in 2004. This solved for the first time the problem of SPPs being unable to be generated at microwave and terahertz frequencies. By etching periodic voids into a metal surface, electromagnetic modes similar to those in optical SPPs can propagate on the surface. These modes exhibit subwavelength, localized, near-field enhanced, and novel dispersion characteristics.

[0004] In 2016, Engheta et al. proposed a method to realize various plasma phenomena by utilizing the modal dispersion of electromagnetic waves in a bounded waveguide filled with a positive permittivity medium, and introduced the concept of Effective Surface Plasmon Polaritons (ESPPs). According to the equivalent medium theory, the equivalent permittivity of the medium filling the waveguide can be tuned by changing the operating frequency, the relative permittivity of the filling medium, and the waveguide size. When the equivalent permittivity of the waveguide is opposite in sign when different media are filled, electromagnetic modes similar to optical SPPs can be found at the interface of the media. Unlike artificial surface plasmon polaritons (SSPPs), ESPPs are not generated by periodic metallic structures, thus eliminating the influence of metal loss on signal transmission and reducing the complexity of structural design. Similarly, ESPPs exhibit strong field confinement and field enhancement near asymptotic frequencies. In recent years, various plasma microwave devices based on SSPPs and ESPPs have emerged, but the waveguide structures are functionally limited, and field enhancement performance still needs improvement. Summary of the Invention

[0005] This invention proposes a fast and slow wave mode composite waveguide based on equivalent artificial surface plasmons, realizing multiple waveguide modes. It can simultaneously have both fast and slow wave modes at the same frequency, or transmit fast and slow waves separately, further enhancing field confinement and field enhancement.

[0006] The present invention adopts the following technical solution:

[0007] A fast and slow wave mode composite waveguide based on equivalent artificial surface plasmons includes a first conducting block and a second conducting block stacked together. The end face edges of the first conducting block and the second conducting block are seamlessly fixedly connected. The input end face and the output end face of the first conducting block serve as the signal input end and the signal output end in the fast wave mode, respectively. The input end face and the output end face of the second conducting block serve as the signal input end and the signal output end in the slow wave mode, respectively.

[0008] As a preferred embodiment of the present invention, the first conductive block is a cuboid shell filled with a medium. One side and a pair of opposite sides of the cuboid shell are openings. The opposite sides of the openings serve as the input end face and the output end face of the first conductive block, respectively. One side of the opening is connected to the second conductive block.

[0009] As a preferred embodiment of the present invention, the second conductive block is a cuboid shell filled with a medium. A pair of opposite faces of the cuboid shell are openings, and the opposite faces of the openings serve as the input end face and the output end face of the second conductive block, respectively. The end face of the cuboid shell corresponding to the second conductive block that connects to the first conductive block includes a plurality of metal units arranged sequentially from the extension direction of the second conductive block.

[0010] As a preferred embodiment of the present invention, the metal units in the plurality of metal units have the same structure. Each metal unit includes a first metal block, a first gradient metal strip group, a metal strip group, a second gradient metal strip group, and a second metal block arranged sequentially along the extension direction of the second conductive block. Hollow air grooves are provided between the first metal block and the first gradient metal strip group, between the first gradient metal strip group and the metal strip group, between the metal strip group and the second gradient metal strip group, and between the second gradient metal strip group and the second metal block. The second metal block in each metal unit is connected to the first metal block in the next sequentially arranged metal unit. The end face of the plurality of metal units connected to the first conductive block is on the same plane as the end face of the cuboid shell corresponding to the second conductive block where the plurality of metal units are located.

[0011] As a preferred embodiment of the present invention, the first gradient metal strip group includes metal strips that start at the height of the first metal block and end at the height of the metal strip group, and whose height gradually decreases from the extension direction of the second conductive block based on a preset height difference; hollow air grooves are provided between each metal strip in the first gradient metal strip group, and the hollow air grooves provided between the first metal block and the first gradient metal strip group, between the first gradient metal strip group and the metal strip group, and between each metal strip in the first gradient metal strip group, the height of the hollow air grooves gradually decreases from the extension direction of the second conductive block based on the same preset height difference as in the first gradient metal strip group.

[0012] As a preferred embodiment of the present invention, the metal strip group includes metal strips of the same shape, and hollow air grooves of the same shape are provided between the metal strips. The hollow air grooves provided between the metal strips are of the same shape as the hollow air grooves provided between the first gradient metal strip group and the metal strip group, and between the metal strip group and the second gradient metal strip group.

[0013] As a preferred embodiment of the present invention, the second gradient metal strip group includes metal strips that start at the height of the metal strip group and end at the height of the second metal block, and whose height gradually increases from the extension direction of the second conductive block based on a preset height difference; hollow air grooves are provided between each metal strip in the second gradient metal strip group, and the hollow air grooves provided between the second metal block and the second gradient metal strip group, between the second gradient metal strip group and the metal strip group, and between each metal strip in the second gradient metal strip group, the height of the hollow air grooves gradually increases from the extension direction of the second conductive block based on the same preset height difference as in the second gradient metal strip group.

[0014] As a preferred embodiment of the present invention, the first metal block and the second metal block have the same shape.

[0015] As a preferred embodiment of the present invention, the preset height difference in the first gradient metal strip group is the same as the preset height difference in the second gradient metal strip group.

[0016] As a preferred embodiment of the present invention, the filling medium is a preset dielectric.

[0017] The beneficial effects of this invention are as follows: This invention proposes a fast-slow wave mode composite waveguide based on equivalent artificial surface plasmons. This equivalent artificial surface plasmon waveguide can support efficient transmission of equivalent artificial surface plasmons over a wide bandwidth; furthermore, it can simultaneously support both fast and slow wave modes at the same frequency, and can also transmit fast and slow waves separately, providing a new approach for waveguide structure design in the microwave band. In addition, this equivalent artificial surface plasmon waveguide is characterized by its small size, ease of integration, low loss, and wide applicability. This plasmon waveguide can also be applied to substrate-integrated waveguides, circular waveguides, etc. Furthermore, the transmission bandwidth of this equivalent artificial surface plasmon waveguide can be adjusted by changing the lateral width of the waveguide block and the height of the metal strip on the upper surface of the second conduction block, providing a high degree of design freedom. Attached Figure Description

[0018] Figure 1 This is a structural diagram of the overall model of the composite waveguide with equivalent artificial surface plasmon fast and slow wave modes according to an embodiment of the present invention.

[0019] Figure 2 This is a front view of the equivalent artificial surface plasmon fast and slow wave mode composite waveguide structure in the embodiment;

[0020] Figure 3 This is a side view of the equivalent artificial surface plasmon fast and slow wave mode composite waveguide port structure in the embodiment;

[0021] Figure 4 yes Figure 2 A magnified view of part A in the diagram;

[0022] Figure 5 yes Figure 2 A magnified view of part B in the diagram;

[0023] Figure 6 This is a dispersion curve diagram of the equivalent artificial surface plasmon fast and slow wave mode composite waveguide unit structure in the embodiment;

[0024] Figure 7 This is an S-parameter diagram of the equivalent artificial surface plasmon fast and slow wave mode composite waveguide port 1 feeding to excite the slow wave mode in the embodiment.

[0025] Figure 8 This is an S-parameter diagram of ports 3 and 4 when the slow-wave mode is excited by feeding port 1 of the equivalent artificial surface plasmon fast and slow wave mode composite waveguide in the embodiment.

[0026] Figure 9 This is an S-parameter diagram of ports 3 and 4 when the fast wave mode is excited by feeding port 3 of the equivalent artificial surface plasmon fast and slow wave mode composite waveguide in the embodiment.

[0027] Figure 10This is an example of the S-parameter diagrams of ports 1 and 2 when the fast wave mode is excited by feeding port 3 of the equivalent artificial surface plasmon fast and slow wave mode composite waveguide.

[0028] In the figure, 1-first conductive block, 2-second conductive block, 3-first metal block, 4-first gradient metal strip group, 5-metal strip group, 6-second gradient metal strip group, 7-second metal block, 8-hollow air groove. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings. The following embodiments will enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way.

[0030] The purpose of this invention is to further enhance field confinement and field enhancement. We propose a novel plasma structure, named Effective Poof Surface Plasmon Polaritons (ESSPPs), by combining SSPPs and ESPPs using waveguide dispersion on SSPPs structures. Analysis of the dispersion characteristics of ESSPPs reveals that this structure can simultaneously exhibit two modes at the same frequency: a fast-wave mode and a slow-wave, surface-wave mode. Figure 2 In this context, A represents the SSPPs structure. Figure 3 It is an ESPPs structure; based on ESSPPs, a fast and slow wave mode composite waveguide is proposed, which is of great significance for improving the capacity of communication channels.

[0031] like Figure 1 As shown, a fast and slow wave mode composite waveguide based on equivalent artificial surface plasmons includes a first conducting block 1 and a second conducting block 2 stacked together. The end face edges of the first conducting block 1 and the second conducting block 2 are seamlessly fixedly connected. The input end face and the output end face of the first conducting block 1 serve as the signal input end and the signal output end in the fast wave mode, respectively. The input end face and the output end face of the second conducting block 2 serve as the signal input end and the signal output end in the slow wave mode, respectively.

[0032] The first conductive block 1 is a cuboid shell filled with a medium. One side and a pair of opposite sides of the cuboid shell are openings. The opposite sides of the openings serve as the input end face and the output end face of the first conductive block 1, respectively. One side of the opening is connected to the second conductive block 2.

[0033] The second conductive block 2 is a cuboid shell filled with a medium. A pair of opposite faces of the cuboid shell are openings. The opposite faces of the openings serve as the input end face and the output end face of the second conductive block 2, respectively. The end face of the cuboid shell corresponding to the second conductive block 2 that is connected to the first conductive block 1 includes several metal units arranged sequentially from the extension direction of the second conductive block 2.

[0034] Specifically, the first conducting block 1 and the second conducting block 2 are integrated, and the dielectric is filled using a dielectric-filled waveguide process.

[0035] Furthermore, the individual metal units among the plurality of metal units have the same structure, such as... Figure 1 , Figure 2 As shown, this is a single metal unit structure. The metal unit includes a first metal block 3, a first gradient metal strip group 4, a metal strip group 5, a second gradient metal strip group 6, and a second metal block 7 arranged sequentially along the extension direction of the second conductive block 2. Hollow air grooves 8 are provided between the first metal block 3 and the first gradient metal strip group 4, between the first gradient metal strip group 4 and the metal strip group, between the metal strip group and the second gradient metal strip group 6, and between the second gradient metal strip group 6 and the second metal block 7. The second metal block 7 in each metal unit is connected to the first metal block 3 in the next sequentially arranged metal unit. The end face of the plurality of metal units connected to the first conductive block 1 is on the same plane as the end face of the cuboid shell corresponding to the second conductive block 2 where the plurality of metal units are located. In this embodiment, the height of the hollow air grooves 8 between the first metal block 3 and the first gradient metal strip group 4, and between the second gradient metal strip group 6 and the second metal block 7, is 0.62 mm.

[0036] In this embodiment, the first conductive block 1, the second conductive block 2, the first metal block 3, the first gradient metal strip group 4, the metal strip group 5, the second gradient metal strip group 6, and the second metal block 7 are all made of copper or aluminum. Specifically, the length w of the parallel side of the boundary line between the first conductive block 1 and the second conductive block 2 is 10 mm, and the thickness h1 of the filling medium of the first conductive block 1 is 3 mm. The thickness h2 of the filling medium of the second conductive block 2 is 4 mm. The width d of the metal strips in the upper port metal strip group and the two gradient metal strip groups of the second conductive block 2 is 0.38 mm, and the height h of the metal strips in the middle region metal strip group is 0.1 mm. The height of the metal (first metal block 3, second metal block 7) of the waveguide blocks at the signal input and signal output ends of the second conductive block 2 is 2.7 mm. The periodic distance p of the metal strips in the metal strip group and the two gradient metal strip groups of the second conductive block 2 is 0.5 mm. Furthermore, the thickness of each air groove in the middle region of the upper end face of the second conductive block 2 is 0.12 mm. The wall thickness of both the first conductive block 1 and the second conductive block 2 is 0.5 mm.

[0037] Furthermore, the first gradient metal strip group 4 includes metal strips that start at the height of the first metal block 3 and end at the height of the metal strip group, and whose height gradually decreases from the extension direction of the second conductive block 2 based on a preset height difference (in this embodiment, the height difference p_trans is 0.18mm). Hollow air grooves 8 are provided between each metal strip in the first gradient metal strip group 4. The hollow air grooves 8 between the first metal block 3 and the first gradient metal strip group 4, between the first gradient metal strip group 4 and the metal strip group, and between each metal strip in the first gradient metal strip group 4, are based on the same preset height difference as in the first gradient metal strip group 4, and their height gradually decreases from the extension direction of the second conductive block 2.

[0038] Furthermore, the metal strip group 5 includes metal strips of the same shape, and hollow air grooves 8 of the same shape are provided between each metal strip. The hollow air grooves 8 provided between each metal strip are of the same shape as the hollow air grooves 8 provided between the first gradient metal strip group 4 and the metal strip group, and between the metal strip group and the second gradient metal strip group 6.

[0039] Furthermore, the second gradient metal strip group 6 includes metal strips that gradually increase in height from the height of the metal strip group to the height of the second metal block 7, and based on a preset height difference (in this embodiment, the height difference p_trans is 0.18mm); each metal strip in the second gradient metal strip group 6 has a hollow air groove 8 between each metal strip. The hollow air grooves 8 between the second metal block 7 and the second gradient metal strip group 6, between the second gradient metal strip group 6 and the metal strip group, and between each metal strip in the second gradient metal strip group 6 have the same preset height difference as those in the second gradient metal strip group 6, and the hollow air grooves 8 gradually increase in height from the direction of the second conductive block 2.

[0040] In this embodiment, the height of the hollow air groove 8 is higher than the height of the metal on both sides of the hollow air groove 8.

[0041] Specifically, the first metal block 3 and the second metal block 7 have the same shape. The preset height difference in the first gradient metal strip group 4 is the same as the preset height difference in the second gradient metal strip group 6. The filling medium is a preset dielectric.

[0042] Regarding the relative permittivity ε of the dielectric of the first conducting block 1 Ⅰ The relative permittivity ε of the dielectric of the second conducting block 2 Ⅲ In a rectangular waveguide filled with dielectric:

[0043]

[0044] Where k is the wave number of the dielectric-filled waveguide, kc Where w is the cutoff wavenumber, and w is the transverse width of the waveguide (i.e., the corresponding wavenumber). Figure 3 w in the middle.

[0045] The equivalent permittivity of a waveguide:

[0046]

[0047] Where, ε e ε is the equivalent dielectric constant, λ is the wavelength, and ε is the lattice. r is the relative permittivity of the dielectric.

[0048] The prerequisite for exciting the equivalent surface plasmon (ESPP) mode is that the real parts of the equivalent dielectric constants of the two dielectrics have opposite signs: Re(ε) e1 )·Re(ε e2 ) < 0;

[0049] Therefore, the relative permittivity ε of the upper dielectric layer is specified in this patent. Ⅰ The relative permittivity ε of the underlying medium Ⅲ Requirements

[0050]

[0051]

[0052]

[0053] In the fast and slow wave mode composite waveguide of the equivalent artificial surface plasmon designed in this scheme, the upper surfaces of the metal blocks at the input end of the first conducting block 1 and the input end of the second conducting block 2 form a first rectangular waveguide; the upper surfaces of the metal blocks at the output end of the first conducting block 1 and the output end of the second conducting block 2 form a second rectangular waveguide; the input end of the second conducting block 2 forms a third rectangular waveguide; the array of metal strips of different heights near the input end of the second conducting block 2 (first graded metal strip group 4) forms a first transition waveguide; the array of metal strips of the same height on the upper surface of the second conducting block 2 (metal strip group) forms a first plasma waveguide supporting the equivalent artificial surface plasmon; the array of metal strips of different heights near the output end of the second conducting block 2 (second graded metal strip group 6) forms a second transition waveguide; and the output end of the second conducting block 2 forms a fourth rectangular waveguide.

[0054] During fast wave mode transmission, the first rectangular waveguide first converts the guided wave signal input at the input terminal into TE10 mode, then transmits it to the second rectangular waveguide, and finally outputs it from the output terminal. TE10 mode is the fundamental mode of the rectangular waveguide and is a fast wave mode.

[0055] During slow-wave mode transmission, the third rectangular waveguide first converts the input waveguide signal into a TE10 mode and then transmits it to the first plasma waveguide via the first transition waveguide. The equivalent artificial surface plasmon polariton is efficiently and rapidly transmitted to the second transition waveguide in a strongly bound slow-wave mode on the first plasma waveguide. The second transition waveguide transmits the TE10 guided wave signal from the equivalent artificial surface plasmon polariton to the fourth rectangular waveguide. The fourth rectangular waveguide converts the TE10 guided wave signal into a normal waveguide signal and outputs it from the output terminal.

[0056] Furthermore, in this embodiment, a fast and slow wave mode composite waveguide based on equivalent artificial surface plasmons includes a first rectangular waveguide, a second rectangular waveguide, a third rectangular waveguide, a first transition waveguide, a first plasma waveguide, a second transition waveguide, and a fourth rectangular waveguide.

[0057] like Figure 2 , Figure 3 As shown, the wall thickness of the first conducting block 1 and the second conducting block 2 is 0.5mm, and the port dimensions of the first rectangular waveguide and the second rectangular waveguide are w*h1=10*3mm. 2 The total length of the first and second rectangular waveguides is 46.26 mm, and the port dimensions of the third and fourth rectangular waveguides are w*h² = 10*4 mm. 2 The lengths of the third and fourth rectangular waveguides are l3 = 10 mm, the lengths of the first and second transition waveguides are l2 = 7.88 mm, and the length of the first plasma waveguide is l1 = 10.5 mm.

[0058] The relative permittivity of the dielectric filling medium of the first conducting block 1 is 3.48, and the relative permittivity of the dielectric filling medium of the second conducting block 2 is 9.

[0059] like Figure 4 , Figure 5 As shown, the width d = 0.38 mm of the metal strips in the first transition waveguide, the second transition waveguide, and the first plasma waveguide, and the periodic distance between the metal strips is p = 0.5 mm. The height g = 0.62 mm of the hollow air trough 8. The height difference p_trans = 0.18 mm between adjacent metal strips in the first and second transition waveguides.

[0060] like Figure 6 As shown, the dispersion characteristics of the unit cell structure of the equivalent artificial surface plasmon fast-slow mode composite waveguide are illustrated. The bandwidth in slow mode is 5-9 GHz, and the bandwidth in fast mode is 8-18 GHz. The operating bandwidth of the fast and slow modes can be adjusted by modifying the geometry of the structure, facilitating device design.

[0061] Simulation results of S-parameters in slow-wave mode are as follows: Figure 7 , Figure 8 As shown, in Figure 7 In the diagram, the solid line represents the transmission coefficient S. 21 The dashed line represents the reflection coefficient S. 11 The operating frequency is 5-9 GHz, and Figure 6 The operating bandwidth of the dispersion curve corresponds to that of mode one, proving the theoretical feasibility of our design. Figure 8 In the middle, the solid line represents the isolation coefficient S. 31 The dashed line represents the isolation coefficient S. 41 Both values ​​are below -10dB, indicating that the electromagnetic waves have good isolation at ports three and four.

[0062] Simulation results of S-parameters in fast wave mode are as follows: Figure 9 , Figure 10 As shown, in Figure 9 In the diagram, the solid line represents the transmission coefficient S. 43 The dashed line represents the reflection coefficient S. 33 .exist Figure 8 In the middle, the solid line represents the isolation coefficient S. 23 The dashed line represents the isolation coefficient S. 13 Both values ​​are below -10dB, indicating that the electromagnetic waves have good isolation between port one and port two.

[0063] This invention designs a fast-slow wave mode composite waveguide based on equivalent artificial surface plasmons. This equivalent artificial surface plasmon waveguide can support efficient transmission of equivalent artificial surface plasmons over a wide bandwidth. Furthermore, it can simultaneously support both fast and slow wave modes at the same frequency, or transmit fast and slow waves separately, providing a new approach to waveguide structure design in the microwave band. In addition, this equivalent artificial surface plasmon waveguide is characterized by its small size, ease of integration, low loss, and wide applicability. This plasmon waveguide can also be applied to substrate-integrated waveguides, circular waveguides, etc. Moreover, the transmission bandwidth of this equivalent artificial surface plasmon waveguide can be adjusted by changing the lateral width of the waveguide block and the height of the metal strip on the upper surface of the second conduction block, providing a high degree of design freedom.

[0064] The above are merely preferred embodiments of the present invention, but do not limit the patent scope of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of the present invention specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the patent protection scope of the present invention.

Claims

1. A fast-slow wave mode composite waveguide based on equivalent artificial surface plasmons, characterized in that, It includes a first conducting block (1) and a second conducting block (2) stacked together, with the end face edges of the first conducting block (1) and the second conducting block (2) being seamlessly fixedly connected; the input end face and the output end face of the first conducting block (1) serve as the signal input end and the signal output end in fast wave mode, respectively; the input end face and the output end face of the second conducting block (2) serve as the signal input end and the signal output end in slow wave mode, respectively. The second conductive block (2) is a cuboid shell and its interior is filled with a medium. A pair of opposite faces of the cuboid shell are openings. The opposite faces of the openings serve as the input end face and the output end face of the second conductive block (2). The end face of the cuboid shell corresponding to the second conductive block (2) connected to the first conductive block (1) includes several metal units arranged sequentially from the extension direction of the second conductive block (2). The metal units in the plurality of metal units have the same structure. The metal unit includes a first metal block (3), a first gradient metal strip group (4), a metal strip group (5), a second gradient metal strip group (6), and a second metal block (7) arranged sequentially along the extension direction of the second conductive block (2). Hollow air grooves (8) are provided between the first metal block (3) and the first gradient metal strip group (4), between the first gradient metal strip group (4) and the metal strip group (5), between the metal strip group (5) and the second gradient metal strip group (6), and between the second gradient metal strip group (6) and the second metal block (7). The second metal block (7) in each metal unit is connected to the first metal block (3) in the next metal unit arranged in sequence. The end face of the plurality of metal units connected to the first conductive block (1) is on the same plane as the end face of the cuboid shell corresponding to the second conductive block (2) where the plurality of metal units are located.

2. The fast and slow wave mode composite waveguide based on equivalent artificial surface plasmons according to claim 1, characterized in that, The first conductive block (1) is a cuboid shell and its interior is filled with a medium. One side and a pair of opposite sides of the cuboid shell are openings. The opposite sides of the openings serve as the input end face and output end face of the first conductive block (1), respectively. One side of the opening is connected to the second conductive block (2).

3. The fast and slow wave mode composite waveguide based on equivalent artificial surface plasmons according to claim 1, characterized in that, The first gradient metal strip group (4) includes metal strips that start at the height of the first metal block (3) and end at the height of the metal strip group (5), and whose height gradually decreases from the extension direction of the second conductive block (2) based on a preset height difference; hollow air grooves (8) are provided between each metal strip in the first gradient metal strip group (4), and the hollow air grooves (8) provided between the first metal block (3) and the first gradient metal strip group (4), between the first gradient metal strip group (4) and the metal strip group, and between each metal strip in the first gradient metal strip group (4), the height of the hollow air grooves (8) gradually decreases from the extension direction of the second conductive block (2) based on the same preset height difference as in the first gradient metal strip group (4).

4. The fast and slow wave mode composite waveguide based on equivalent artificial surface plasmons according to claim 1, characterized in that, The metal strip group (5) includes metal strips of the same shape, and hollow air grooves (8) of the same shape are provided between each metal strip. The hollow air grooves (8) provided between each metal strip are of the same shape as the hollow air grooves (8) provided between the first gradient metal strip group (4) and the metal strip group, and between the metal strip group and the second gradient metal strip group (6).

5. The fast and slow wave mode composite waveguide based on equivalent artificial surface plasmons according to claim 4, characterized in that, The second gradient metal strip group (6) includes metal strips that start at the height of the metal strip group (5) and end at the height of the second metal block (7), and whose height gradually increases from the extension direction of the second conductive block (2) based on a preset height difference; hollow air grooves (8) are provided between each metal strip in the second gradient metal strip group (6), and the hollow air grooves (8) provided between the second metal block (7) and the second gradient metal strip group (6), between the second gradient metal strip group (6) and the metal strip group, and between each metal strip in the second gradient metal strip group (6), based on the same preset height difference as in the second gradient metal strip group (6), the height of the hollow air grooves (8) gradually increases from the extension direction of the second conductive block (2).

6. The fast and slow wave mode composite waveguide based on equivalent artificial surface plasmons according to claim 5, characterized in that, The first metal block (3) and the second metal block (7) have the same shape.

7. The fast and slow wave mode composite waveguide based on equivalent artificial surface plasmons according to claim 5, characterized in that, The preset height difference in the first gradient metal strip group (4) is the same as the preset height difference in the second gradient metal strip group (6).

8. A fast-slow wave mode composite waveguide based on equivalent artificial surface plasmons according to claim 1 or 2, characterized in that, The filling medium is a preset dielectric.

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