A broadband and highly efficient coupling device for terahertz spoof surface plasmons, a preparation method thereof, and applications thereof

Abstract

The present invention discloses a broadband and efficient coupling device for terahertz spoof surface plasmons, a preparation method thereof and an application thereof, belonging to the technical field of terahertz on-chip passive devices. It is successively connected from left to right by a standard rectangular waveguide I, a converter II, a spoof surface plasmon waveguide III, a converter II and a standard rectangular waveguide I. The present invention realizes wave vector matching, polarization matching and impedance matching before and after mode conversion with a parameterized three-dimensional metal surface. Through structural parameter design and optimization, broadband and efficient conversion from the TE mode of the standard rectangular waveguide to the spoof surface plasmon mode is achieved. The present invention uses the geometric characteristics of the structure to disassemble the overall device for processing compatibility, separately prints the disassembled device structures through a high-precision 3D printing process, combines with a magnetron sputtering method to metallize the device surface, and finally completes the overall assembly of the device using the reserved holes. This device has the advantages of high confinement, low loss, and tunability, etc.

Description

Technical Field

[0001] The present invention belongs to the technical field of terahertz on-chip passive devices, and particularly relates to a broadband and efficient coupling device for terahertz pseudo-surface plasmons, a preparation method thereof, and an application thereof. Technical Background

[0002] Terahertz waves are electromagnetic waves with frequencies in the range of 0.1 - 10 terahertz (THz), and the wavelength range is 0.03 - 3 millimeters (mm). In recent years, terahertz technology has made remarkable progress due to its great application potential in fields such as wireless communication, medical imaging, space remote sensing, material characterization, and security inspection. Terahertz pseudo-surface plasmons utilize sub-wavelength artificial electromagnetic microstructures to simulate the dispersion curve of metals near the plasma frequency, thereby realizing an electromagnetic mode similar to surface plasmons in the terahertz frequency band. This electromagnetic mode can effectively confine electromagnetic signals at the metal-air interface and propagate along the interface, so it has become one of the means for signal manipulation and processing on terahertz chips, and has potential application value in fields such as on-chip integrated photon systems and sixth-generation communication technologies.

[0003] Currently, the methods for coupling and exciting terahertz pseudo-surface plasmons mainly include prism coupling and grating coupling. These two methods both use terahertz wave radiation with specific polarization and direction to generate in-plane wave vectors, and are usually used in terahertz systems based on photon sources and free space optics. The pseudo-surface plasmon coupling methods based on vector network analysis systems mainly include dipole antenna radiation coupling, substrate integrated waveguide coupling, and rectangular waveguide coupling. However, limited by device size, material dispersion, and processing technology, these methods are currently mainly applied to the microwave frequency band and cannot achieve broadband and efficient coupling of terahertz pseudo-surface plasmons in a vector network analysis system. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a broadband and efficient coupling device for converting the rectangular waveguide mode in the terahertz frequency band to the pseudo-surface plasmon mode, a preparation method thereof, and an application thereof. The present invention uses a parameterized three-dimensional metal surface to achieve wave vector matching, polarization matching, and impedance matching before and after mode conversion. Through structural parameter design and optimization, broadband and efficient conversion from the standard rectangular waveguide TE10 mode to the pseudo-surface plasmon mode is realized. Since the device involves the processing of large-size complex three-dimensional metal structures with characteristic dimensions on the order of 10 micrometers, the current micro-nano processing technology cannot directly process it. Therefore, the present invention uses the geometric characteristics of the structure to disassemble the device as a whole for processing compatibility, prints the disassembled device structures respectively by a high-precision 3D printing process, combines with a magnetron sputtering method to metallize the surface of the device, and finally completes the overall assembly of the device using the reserved holes.

[0005] The present invention is realized through the following technical solutions:

[0006] A broadband and highly efficient coupling device for terahertz spoof surface plasmons. The coupling device is an assembled metallized structure. Taking the propagation direction of the wave in the rectangular waveguide as the x-axis, the long side direction of the rectangular waveguide port as the y-axis, and the short side direction of the rectangular waveguide port as the z-axis, the broadband and highly efficient coupling device is sequentially composed of a standard rectangular waveguide I 20, a converter II 30, a spoof surface plasmon waveguide III 40, a converter II 30, and a standard rectangular waveguide I 20 connected from left to right along the x-axis; The TE10 mode electromagnetic wave emitted from the standard rectangular waveguide I 20 is coupled by the converter II 30 into the electromagnetic wave of the spoof surface plasmon mode supported by the spoof surface plasmon waveguide III 40, and then coupled by the converter II 30 into the TE10 mode electromagnetic wave supported by the standard rectangular waveguide I 20.

[0007] Furthermore, the standard rectangular waveguide I 20 is composed of a rectangular waveguide upper part 1 and a rectangular waveguide base 6, and the rectangular waveguide upper part 1 is inserted on the rectangular waveguide base 6; Among them, the structures and dimensions of the two standard rectangular waveguides I are the same and symmetrically distributed, and are respectively located at the left and right ends of the broadband and highly efficient coupling device;

[0008] The spoof surface plasmon waveguide III 40 is composed of a base 12 and a second metal square column array 13, and the second metal square column array 13 is arranged on the base 12.

[0009] Furthermore, the converter II 30 is composed of a flared upper part 2, a wedge-shaped conversion base 8, and a first metal square column array 10 with increasing height. The flared upper part 2 is inserted on the wedge-shaped conversion base 8, and the first metal square column array 10 with increasing height is arranged on the wedge-shaped conversion base 8. The first metal square column array 10 with increasing height is located in the cavity structure formed by the flared upper part 2 and the wedge-shaped conversion base 8; One end of the flared upper part 2 is connected to the standard rectangular waveguide I 20, and the other end is connected to the spoof surface plasmon waveguide III 40; Among them, the flared upper part 2 is used to achieve impedance matching before and after mode conversion, and the first metal square column array 10 with increasing height is used to achieve wave vector matching and polarization matching before and after mode conversion.

[0010] Furthermore, the rectangular waveguide upper part 1 is a rectangular groove structure with a downward opening, the flared upper part 2 is a curved trapezoidal groove structure with a downward opening, and rectangular protrusion structures are provided on the lower surfaces of the two side walls of the groove structure. Rectangular holes are provided on the rectangular waveguide base 6, the wedge-shaped conversion base 8, and the base 12. The rectangular protrusion structures cooperate with the rectangular holes to achieve plug-in fixation, playing a role in assembling and fixing the device.

[0011] Further, the standard rectangular waveguide I 20 has international standard dimensions. If the operating frequency is between 90 - 140 GHz, the WR-8 waveguide with dimensions of 2.032x1.016 (mm) is used; if it is between 110 - 170 GHz, the WR-6 / WR-6.5 / WR-7 waveguide with dimensions of 1.651x0.8255 (mm) is used; if it is between 140 - 220 GHz, the WR-5 waveguide with dimensions of 1.2954x0.6477 (mm) is used; if it is between 172 - 260 GHz, the WR-4 waveguide with dimensions of 1.0922x0.5461 (mm) is used; if it is between 220 - 330 GHz, the WR-3 waveguide with dimensions of 0.8636x0.4318 (mm) is used.

[0012] Further, the length of the upper part 1 of the rectangular waveguide in the x-axis direction, the thicknesses of the upper wall and both side walls are all 0.01 - 10000 mm. The length of the rectangular waveguide substrate 6 in the x-direction is 0.01 - 10000 mm, the length in the y-direction is 0.4318 - 10000 mm, and the height in the z-direction is 0.01 - 2 mm;

[0013] The length of the wedge-shaped conversion substrate 8 in the x-direction is 0.01 - 10000 mm, the length in the y-direction is 0.4318 - 10000 mm, the height in the z-direction is 0.01 - 2 mm. The length of the first metal square post array 10 with increasing height in the x-direction is 0.01 - 2 mm, the width in the y-direction is 0.01 - 2.032 mm, the height in the z-direction gradually increases from zero to the same height as the second metal square post array 13 with the same increment, and the period in the x-direction is 0.01 - 2 mm;

[0014] The length of the substrate 12 in the x-direction is 0.01 - 10000 mm, the width in the y-direction is 0.4318 - 10000 mm, and the thickness in the z-direction is 0.01 - 10000 mm. The length of the second metal square post array 13 in the x-direction is 0.01 - 2 mm, the width in the y-direction is 0.01 - 2.032 mm, the height in the z-direction is 0.01 - 2 mm, which is the same as the height of the rectangular waveguide substrate 6 and the wedge-shaped conversion substrate 8. The period in the x-direction is 0.01 - 2 mm, and the number is 1 - 100000;

[0015] The lengths of the rectangular protrusion structure and the rectangular hole positions in the x, y, and z directions are all 0.01 - 10000 mm.

[0016] Further, the top wall curve of the flared upper part 2 is z = C 1 e αx +C 2 (x 1 < x < x 2 ) where, α = 0.1, (x 1 , z 1 ) and (x 2 , z 2 ) are the starting and ending points of the curve, and the thickness of the upper wall and side wall of the flared opening and the distance from the top of the upper wall of the flared opening to the upper part of the metal square column array are 0.01 - 10000 mm.

[0017] On the other hand, the present invention also provides a preparation method for a broadband and efficient coupling device of terahertz pseudo-surface plasmon, which specifically includes the following steps:

[0018] First, the lower part and the upper part of the broadband and efficient coupler are respectively printed by a high-precision 3D printing process;

[0019] Then, magnetron sputtering is used to metallize the surface of the device;

[0020] Finally, the overall assembly of the device is completed by using the reserved holes.

[0021] Furthermore, the 3D printing material is photosensitive resin, and the metal materials used in the magnetron sputtering method are gold, silver or purple copper; at room temperature, the density of gold is 19.32 g / cm 3 , and the resistivity is 2.05×10 -8 (Ω·m), the density of silver is 10.49 g / cm 3 , and the resistivity is 1.586×10 -8 (Ω·m), the density of purple copper is 8.89 g / cm 3 , and the resistivity is 1.75×10 -8 (Ω·m).

[0022] In the third aspect, the present invention also provides an application of a broadband and efficient coupling device of terahertz pseudo-surface plasmon, including applications for realizing compact waveguide jumpers in millimeter-wave chips and realizing millimeter-wave out-of-plane signal radiation functions.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] (1). By using 3D printing technology and metal coating technology, the problem that it is currently impossible to achieve broadband and efficient coupling of pseudo-surface plasmon in the terahertz band is solved, and the practical preparation of a broadband and efficient coupling device for the conversion from rectangular waveguide mode to pseudo-surface plasmon mode in the terahertz band of 90 - 330 GHz is realized;

[0025] (2). This device has the advantages of high confinement, low loss, and tunability, and can be widely used in the preparation of devices in other fields of the terahertz band. Description of the Drawings

[0026] Figure 1Figure (a) is a schematic diagram of the overall structure of a broadband and highly efficient coupling device for terahertz pseudo-surface plasmon polaritons according to the present invention;

[0027] Figure 1 Figure (b) is an x-z cross-sectional view of a broadband and highly efficient coupling device for terahertz pseudo-surface plasmon polaritons according to the present invention;

[0028] In the figure: standard rectangular waveguide I 20, converter II 30, pseudo-surface plasmon polariton waveguide III 40;

[0029] Figure 2 Figure is a schematic diagram of the structural breakdown of a broadband and highly efficient coupling device for terahertz pseudo-surface plasmon polaritons according to the present invention;

[0030] In the figure: upper part of the rectangular waveguide 1, flared upper part 2, rectangular protrusions (3, 4, 5), rectangular waveguide substrate 6, wedge-shaped conversion substrate 8, first metal square pillar array 10 with increasing height, rectangular hole positions (7, 9, 11), substrate 12, second metal square pillar array 13;

[0031] Figure 3 Figure (a) is a partial schematic diagram of converter II 30 in a broadband and highly efficient coupling device for terahertz pseudo-surface plasmon polaritons according to the present invention;

[0032] Figure 3 Figure (b) is a partial schematic diagram of the second metal square pillar array 13 in a broadband and highly efficient coupling device for terahertz pseudo-surface plasmon polaritons according to the present invention;

[0033] Figure 4 Figure (a) is a dispersion diagram of the metal square pillars in a broadband and highly efficient coupling device for terahertz pseudo-surface plasmon polaritons according to the present invention;

[0034] Figure 4 Figure (b) is the S-parameter transmission spectrum of a broadband and highly efficient coupling device for terahertz pseudo-surface plasmon polaritons according to the present invention;

[0035] Figure 4 Figure (c) is the E z component (V / m) schematic diagram on a plane 0.3 mm above the surface of the metal square pillar array at 115 GHz in a broadband and highly efficient coupling device for terahertz pseudo-surface plasmon polaritons according to the present invention;

[0036] Figure 5 Figure (a) is a schematic diagram of the overall structure of a millimeter-wave on-chip compact waveguide jumper device according to the present invention;

[0037] Figure 5 Figure (b) is an x-z cross-sectional view of a millimeter-wave on-chip compact waveguide jumper device according to the present invention and a partial schematic diagram of the jumper part;

[0038] Figure 6 S21 transmission spectrum of the millimeter-wave on-chip compact waveguide jumper device implemented by the present invention;

[0039] Figure 7 Simulated electric field distribution of the millimeter-wave on-chip compact waveguide jumper device implemented by the present invention at 115 GHz. The inset shows the local field distribution of the jumper part;

[0040] Figure 8 (a) shows the overall structural schematic diagram of the millimeter-wave out-of-plane signal radiation functional device implemented by the present invention;

[0041] Figure 8 (b) shows the x-z cross-sectional view of the millimeter-wave out-of-plane signal radiation functional device implemented by the present invention and the local schematic diagram of the right-angled part of the rectangular waveguide;

[0042] Figure 9 Simulated electric field distribution of the millimeter-wave out-of-plane signal radiation functional device implemented by the present invention at 115 GHz. The inset shows the local field distribution of the right-angled part of the rectangular waveguide. Detailed implementation manners

[0043] The technical solution of the present invention will be further specifically described below with reference to the accompanying drawings.

[0044] Embodiment 1

[0045] As Figure 1 shown in (a), the present invention provides a broadband and efficient coupling device for terahertz spoof surface plasmons. The coupling device is an assembled metallized structure. Taking the propagation direction of the wave in the rectangular waveguide as the x-axis, the long side direction of the rectangular waveguide port as the y-axis, and the short side direction of the rectangular waveguide port as the z-axis, along the x-axis, the broadband and efficient coupler sequentially consists of a standard rectangular waveguide Ⅰ20 as shown in Figure 1 (b), a converter Ⅱ30, a spoof surface plasmon waveguide Ⅲ40, a converter Ⅱ30, and a standard rectangular waveguide Ⅰ20; wherein, the standard rectangular waveguide Ⅰ20 adopts a WR-8 waveguide with an operating frequency between 90 - 140 GHz, and its international standard size is 2.032 x 1.016 (mm).

[0046] The TE10 mode electromagnetic wave emitted from the WR-8 standard rectangular waveguide Ⅰ20 is coupled into the spoof surface plasmon mode electromagnetic wave supported by the spoof surface plasmon waveguide Ⅲ40 through the converter Ⅱ30, and then coupled into the TE10 mode electromagnetic wave supported by the WR-8 standard rectangular waveguide Ⅰ20 through the converter Ⅱ30; wherein, the converter Ⅱ30 is used to achieve wave vector matching, polarization matching, and impedance matching before and after mode conversion, wherein, Figure 2The first metal square post array 10 with increasing height therein is used to achieve wave vector matching and polarization matching before and after mode conversion, and the flared upper part 2 is used to achieve impedance matching before and after mode conversion.

[0047] The standard rectangular waveguide I 20 is composed of a rectangular waveguide upper part 1 and a rectangular waveguide substrate 6, and the rectangular waveguide upper part 1 is inserted on the rectangular waveguide substrate 6; wherein, the structures and dimensions of two standard rectangular waveguides I are the same and symmetrically distributed, and are respectively located at the left and right ends of the broadband high-efficiency coupling device;

[0048] The pseudo-surface plasmon waveguide III 40 is composed of a substrate 12 and a second metal square post array 13, and the second metal square post array 13 is arranged on the substrate 12.

[0049] The converter II 30 is composed of a flared upper part 2, a wedge-shaped conversion substrate 8 and a first metal square post array 10 with increasing height. The flared upper part 2 is inserted on the wedge-shaped conversion substrate 8, and the first metal square post array 10 with increasing height is arranged on the wedge-shaped conversion substrate 8. The first metal square post array 10 with increasing height is located in the cavity structure formed by the flared upper part 2 and the wedge-shaped conversion substrate 8; one end of the flared upper part 2 is connected to the standard rectangular waveguide I 20, and the other end is connected to the pseudo-surface plasmon waveguide III 40; wherein, the flared upper part 2 is used to achieve impedance matching before and after mode conversion, and the first metal square post array 10 with increasing height is used to achieve wave vector matching and polarization matching before and after mode conversion.

[0050] The rectangular waveguide upper part 1 is a rectangular groove structure with a downward opening, and the flared upper part 2 is a curved trapezoidal groove structure with a downward opening. Rectangular protrusion structures are arranged on the lower surfaces of the two side walls of the groove structure. Rectangular holes are arranged on the rectangular waveguide substrate 6, the wedge-shaped conversion substrate 8 and the substrate 12. The rectangular protrusion structures cooperate with the rectangular holes to achieve plug-in fixation, playing a role in assembling and fixing the device;

[0051] Among them, the x-direction length of the WR-8 standard rectangular waveguide I 20 is 2 mm, the x-direction length of the converter II 30 is 7.5 mm, and the x-direction length of the pseudo-surface plasmon waveguide III 40 is 12.35 mm. The upper wall thicknesses of the WR-8 standard rectangular waveguide I 20 and the converter II 30 are both 1 mm, and the side wall thicknesses are both 1.5 mm. The y-direction length of the rectangular waveguide substrate 6 and the wedge-shaped conversion substrate 8 is 5.032 mm, the z-direction height is 0.45 mm, the x-direction length of the first metal square post array 10 with increasing height is 0.1 mm, the y-direction width is 0.45 mm, and the z-direction height increases from h 1 = 0.0225 mm to h 2= 0.45 mm, the increment Δh is 0.0225 mm, the period in the x - direction is 0.25 mm, and the distance s from the top of the upper wall of the flared opening to above the metal square - column array is 2.5 mm; the length of the substrate 12 in the x - direction is 31.35 mm, the width in the y - direction is 8 mm, and the thickness in the z - direction is 1 mm. As Figure 3 shown in (b) of

[0052] As Figure 2 shown, the length of the rectangular protrusion structures (3, 4, 5) and the rectangular hole positions (7, 9, 11) in the x - direction is 1 ± 0.005 mm, the width in the y - direction is 1 ± 0.005 mm, the height in the z - direction of the rectangular protrusion 3 and the rectangular hole position 7 is 1.45 ± 0.005 mm, the height in the z - direction of the rectangular protrusion 4 and the rectangular hole position 9 is 1.4 ± 0.005 mm, and the height in the z - direction of the rectangular protrusion 5 and the rectangular hole position 11 is 1 ± 0.005 mm.

[0053] As Figure 3 shown in (a) of 1 e αx + C 2 (x 1 < x < x 2 ), where α = 0.1, (x 1 , z 1 ) and (x 2 , z 2 ) are the starting and ending points of the curve, and the thickness of the upper wall and side wall of the flared opening and the distance from the top of the upper wall of the flared opening to above the metal square - column array are 0.01 - 10000 mm.

[0054] Example 2

[0055] As Figure 2 shown, this example provides a preparation method for a broadband and highly efficient coupling device of terahertz pseudo - surface plasmons, which specifically includes the following steps:

[0056] First, the lower part and the upper part of the broadband and highly efficient coupler are respectively printed by a high - precision 3D printing process;

[0057] Then, magnetron sputtering is used to metallize the surface of the device;

[0058] Finally, the overall assembly of the device is completed by using the reserved hole positions.

[0059] Among them, the 3D printing material is photosensitive resin, and the metal materials used in the magnetron sputtering method are selected from gold, silver or purple copper; at room temperature, the density of gold is 19.32 g / cm 3 , and the resistivity is 2.05×10 -8 (Ω·m), the density of silver is 10.49 g / cm 3 , and the resistivity is 1.586×10 -8 (Ω·m), the density of purple copper is 8.89 g / cm 3 , and the resistivity is 1.75×10 -8 (Ω·m).

[0060] As can be seen from Figure 4 (a), the dispersion curve of the periodic metal square column is always on the right side of the light and gradually approaches 145 GHz. The dispersion curve of the pseudo-surface plasmon mode it supports is similar to the dispersion curve of the surface plasmon mode supported by the dielectric-metal interface. Therefore, this structure can well simulate the surface plasmon and confine the electromagnetic wave to the metal surface. Apply an electromagnetic wave in the TE10 mode at the port of the WR-8 standard rectangular waveguide Ⅰ20, and use the CST STUDIO SUITE electromagnetic finite element simulation software to obtain the S21 and S11 transmission spectra as shown in Figure 4 (b). Its S21 transmission spectrum remains above -2 dB within 90 - 140 GHz, and its S11 reflection spectrum is below -15 dB, showing high-efficiency transmission ability within a 50 GHz broadband. Figure 4 (c) shows the E z field distribution on the plane 0.3 mm above the surface of the metal square column array at 115 GHz. The electromagnetic wave is well transmitted from the WR-8 standard rectangular waveguide Ⅰ20 on the left to the WR-8 standard rectangular waveguide Ⅰ20 on the right.

[0061] Example 3

[0062] Utilize a broadband and high-efficiency coupling device of terahertz pseudo-surface plasmons and an infinite anisotropic medium (IAM) to realize a compact waveguide jumper within a millimeter-wave chip.

[0063] The on-chip integrated electromagnetic link of the 6G mobile communication technology currently being explored not only requires high-efficiency broadband transmission of electromagnetic waves, but also needs to achieve the integration and miniaturization of the on-chip system. Since one of the main limitations of plasmonic circuits and devices that use surface electromagnetic waves as information and energy carriers is the inability to perfectly guide the surface electromagnetic wave to turn, a compact waveguide jumper system within a millimeter-wave chip is designed using a broadband and high-efficiency coupling device of terahertz pseudo-surface plasmons and an infinite anisotropic medium (IAM) proposed by the present invention, which is of great significance for the interconnection within and between 6G signal chips.

[0064] The specific steps are as follows:

[0065] (1) Design and implement the structure of a compact waveguide jumper device on a millimeter-wave chip;

[0066] An efficient broadband coupling device that uses a right-angled rectangular waveguide containing IAM medium to connect two terahertz spoof surface plasmon polaritons. The overall structural schematic diagram is as shown in Figure 5 (a) of Figure. Since there is no ideal homogeneous IAM medium in nature, a periodic metal sheet structure is contained in a WR-8 rectangular waveguide to simulate the natural IAM medium. Among them, the period of the metal sheet structure is 0.1 mm, and the duty cycle is 0.1. The x-z cross-sectional view of the compact waveguide jumper structure on the millimeter-wave chip and the local schematic diagram of the jumper part are as shown in Figure 5 (b) of Figure.

[0067] (2) Characterize the performance of the compact waveguide jumper on the millimeter-wave chip;

[0068] The transmission spectrum and field distribution of the compact waveguide jumper on the millimeter-wave chip were simulated using CST electromagnetic finite element simulation software at around 100 GHz;

[0069] Figure 6 is the S21 transmission spectrum of this structure. S21 remains above -5 dB within 90 - 125 GHz, demonstrating its broadband and efficient transmission ability;

[0070] Figure 7 is the simulated electric field distribution of this structure at 115 GHz. The inset is the local field distribution of the waveguide jumper part, which confirms that the compact waveguide jumper on the millimeter-wave chip has the ability to perfectly turn electromagnetic waves. At the same time, due to the non-diffracting transmission characteristics reflected by the IAM dispersion curve, this method can not only achieve a perfect turn with a zero turning radius of electromagnetic signals, but also the turning angle can be designed arbitrarily.

[0071] Example 4

[0072] Utilize a broadband and efficient coupling device of terahertz spoof surface plasmon polaritons and an infinite anisotropic medium (IAM) of the present invention to realize the function of millimeter-wave out-of-plane signal radiation.

[0073] Based on a broadband and efficient coupling device of terahertz spoof surface plasmon polaritons proposed by the present invention, using IAM medium and a horn antenna, electromagnetic signals carrying information and energy are radiated out-of-plane to achieve signal transmission and reception. This function is of great significance for on-chip - free space interaction of 6G signals.

[0074] The specific steps are as follows:

[0075] (1) Design and implement the structure of a device for millimeter-wave out-of-plane signal radiation function;

[0076] Connect a right-angled rectangular waveguide containing IAM medium between a broadband and efficient coupling device of terahertz spoof surface plasmon polaritons and a horn antenna in the present invention. The overall structural schematic diagram is as shown in Figure 8 (a) of the figure. Similarly, a periodic metal sheet structure is contained in the WR-8 rectangular waveguide to simulate the natural IAM medium. The period and duty cycle are the same as those in Embodiment 3. The x-z cross-sectional view of the device for realizing the out-of-plane signal radiation function of millimeter waves and the partial schematic diagram of the right-angled part of the rectangular waveguide are as shown in Figure 8 (b) of the figure.

[0077] (2) Characterize the performance of the device for realizing the out-of-plane signal radiation function of millimeter waves;

[0078] The electric field distribution of the device for realizing the out-of-plane signal radiation function of millimeter waves based on IAM at 115 GHz is simulated by using CST electromagnetic finite element simulation software, as shown in Figure 9 The figure. The inset shows the local field distribution of the right-angled part of the rectangular waveguide, which confirms that the device for realizing the out-of-plane signal radiation function of millimeter waves based on IAM has a good out-of-plane radiation function.

Claims

1. A broadband and highly efficient coupling device for terahertz spoof surface plasmons, characterized in that, the coupling device is an assembled metallized structure. Taking the propagation direction of the wave in the rectangular waveguide as the x-axis, the long side direction of the rectangular waveguide port as the y-axis, and the short side direction of the rectangular waveguide port as the z-axis, the broadband and highly efficient coupling device is sequentially composed of a standard rectangular waveguide I (20), a converter II (30), a spoof surface plasmon waveguide III (40), a converter II (30), and a standard rectangular waveguide I (20) connected from left to right along the x-axis; the TE10 mode electromagnetic wave emitted from the standard rectangular waveguide I (20) is coupled into the spoof surface plasmon mode electromagnetic wave supported by the spoof surface plasmon waveguide III (40) through the converter II (30), and then coupled into the TE10 mode electromagnetic wave supported by the standard rectangular waveguide I (20) through the converter II (30); the standard rectangular waveguide I (20) is composed of a rectangular waveguide upper part (1) and a rectangular waveguide substrate (6), and the rectangular waveguide upper part (1) is inserted on the rectangular waveguide substrate (6); wherein, the structures and dimensions of the two standard rectangular waveguides I are the same and symmetrically distributed, and are respectively located at the left and right ends of the broadband and highly efficient coupling device; the spoof surface plasmon waveguide III (40) is composed of a substrate (12) and a second metal square column array (13), and the second metal square column array (13) is arranged on the substrate (12); the converter II (30) is composed of a flared upper part (2), a wedge-shaped conversion substrate (8), and a first metal square column array (10) with increasing height. The flared upper part (2) is inserted on the wedge-shaped conversion substrate (8), and the first metal square column array (10) with increasing height is arranged on the wedge-shaped conversion substrate (8). The first metal square column array (10) with increasing height is located in the cavity structure formed by the flared upper part (2) and the wedge-shaped conversion substrate (8); one end of the flared upper part (2) is connected to the standard rectangular waveguide I (20), and the other end is connected to the spoof surface plasmon waveguide III (40); wherein, the flared upper part (2) is used to achieve impedance matching before and after mode conversion, and the first metal square column array (10) with increasing height is used to achieve wave vector matching and polarization matching before and after mode conversion.

2. A broadband and highly efficient coupling device for terahertz spoof surface plasmons according to claim 1, characterized in that, the rectangular waveguide upper part (1) is a rectangular groove structure with a downward opening, the flared upper part (2) is a curved trapezoidal groove structure with a downward opening, and rectangular protrusion structures are arranged on the lower surfaces of the two side walls of the groove structure. Rectangular holes are arranged on the rectangular waveguide substrate (6), the wedge-shaped conversion substrate (8), and the substrate (12). The rectangular protrusion structures cooperate with the rectangular holes to achieve plug-in fixation, playing the role of assembling and fixing the device.

3. A broadband and highly efficient coupling device for terahertz spoof surface plasmons according to claim 2, characterized in that, The standard rectangular waveguide I (20) has international standard dimensions. If the operating frequency is between 90 - 140 GHz, the WR-8 waveguide with dimensions of 2.032x1.016 mm is used; if between 110 - 170 GHz, the WR-6 / WR-6.5 / WR-7 waveguide with dimensions of 1.651x0.8255 mm is used; if between 140 - 220 GHz, the WR-5 waveguide with dimensions of 1.2954x0.6477 mm is used; if between 172 - 260 GHz, the WR-4 waveguide with dimensions of 1.0922x0.5461 mm is used; if between 220 - 330 GHz, the WR-3 waveguide with dimensions of 0.8636x0.4318 mm is used.

4. A broadband and highly efficient coupling device for terahertz pseudo-surface plasmons as described in claim 3, characterized in that, the length of the upper part (1) of the rectangular waveguide in the x-axis direction, the thicknesses of the upper wall and the two side walls are all 0.01 - 10000 mm, the length of the rectangular waveguide substrate (6) in the x-direction is 0.01 - 10000 mm, the length in the y-direction is 0.4318 - 10000 mm, and the height in the z-direction is 0.01 - 2 mm; the length of the wedge-shaped conversion substrate (8) in the x-direction is 0.01 - 10000 mm, the length in the y-direction is 0.4318 - 10000 mm, the height in the z-direction is 0.01 - 2 mm, the length of the first metal square column array (10) with increasing height in the x-direction is 0.01 - 2 mm, the width in the y-direction is 0.01 - 2.032 mm, the height in the z-direction gradually increases from zero to the same height as the second metal square column array (13) with the same increment, and the period in the x-direction is 0.01 - 2 mm; the length of the substrate (12) in the x-direction is 0.01 - 10000 mm, the width in the y-direction is 0.4318 - 10000 mm, the thickness in the z-direction is 0.01 - 10000 mm; the length of the second metal square column array (13) in the x-direction is 0.01 - 2 mm, the width in the y-direction is 0.01 - 2.032 mm, the height in the z-direction is 0.01 - 2 mm, which is the same height as the rectangular waveguide substrate (6) and the wedge-shaped conversion substrate (8), the period in the x-direction is 0.01 - 2 mm, and the number is 1 - 100000; the lengths of the rectangular protrusion structure and the rectangular hole positions in the x, y, and z directions are all 0.01 - 10000 mm.

5. A broadband and highly efficient coupling device for terahertz pseudo-surface plasmons as described in claim 2, characterized in that, The top wall curve of the flared upper part (2) is z = C 1 e αx +C 2 , x 1 <x<x 2 , where α = 0.1, (x 1 , z 1 ) and (x 2 , z 2 ) are the starting and ending points of the curve, and the thickness of the upper wall and side wall of the flared part and the distance from the top of the upper wall of the flared part to the metal square column array are 0.01 - 10000 mm.

6. A preparation method for a broadband and highly efficient coupling device for terahertz pseudo-surface plasmons as described in claim 1, characterized in that, specifically includes the following steps: First, both the lower component and the upper component of the broadband and highly efficient coupler are printed respectively by a high-precision 3D printing process; Then, magnetron sputtering is used to achieve metallization of the device surface; Finally, the overall assembly of the device is completed using the reserved hole positions.

7. The preparation method of a broadband and high-efficiency coupling device for terahertz pseudo-surface plasmon as claimed in claim 6, characterized in that, The 3D printing material is photosensitive resin, and the metal materials used in the magnetron sputtering method are gold, silver or red copper; at room temperature, the density of gold is 19.32 g / cm 3 , and the resistivity is 2.05×10 -8 Ω·m, the density of silver is 10.49 g / cm 3 , and the resistivity is 1.586×10 -8 Ω·m, the density of red copper is 8.89 g / cm 3 , and the resistivity is 1.75×10 -8 Ω·m.

8. The application of a broadband and high-efficiency coupling device for terahertz pseudo-surface plasmon as claimed in claim 1, characterized in that, it includes applications in realizing a compact waveguide jumper within a millimeter-wave chip and realizing the function of millimeter-wave out-of-plane signal radiation.

Images