CN116736432A - Substrate integrated topological waveguide based on chiral boundary state - Google Patents
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Abstract
The invention provides a substrate integrated topological waveguide based on chiral boundary states, which comprises an upper metal film layer, a dielectric substrate F4B, a lower metal layer and a microstrip transmission line; the interfaces at two sides of the substrate integrated topological waveguide are respectively set into an A-type interface and a B-type interface, the boundaries of the A-type interface and the B-type interface are saw-tooth-shaped, the boundary between the two sides and air is respectively set into a waveguide channel 1 and a waveguide channel 2, the waveguide channel 1 and the waveguide channel 2 are used for supporting the transmission of chiral boundary states, and the propagation directions of the chiral boundary states transmitted by the waveguide channel 1 and the waveguide channel 2 at a unified frequency are opposite; the upper metal film layer is provided with a plurality of combined air holes, and the combined air holes are formed by connecting three Y-shaped air holes. By introducing a microstrip transmission line with a conical gradual change part and adopting a triangular transition structure at the initial end part of a waveguide channel, the efficient coupling and conversion between the traditional guided wave and chiral boundary wave are realized, and the low-loss and efficient transmission of electromagnetic signals along the topological waveguide is realized.
Description
Technical Field
The invention relates to the technical field of topological photonic crystals, in particular to a substrate integrated topological waveguide based on chiral boundary states.
Background
Photon topological insulators are topological physics of research photons, have become a leading field of photonics, and have recently received widespread attention. Topology boundary states or surface states are rendered immune to perturbing (e.g., defects and kinks) interfaces and robust to backscatter and transport due to the presence of various boundary states or surface states in the photon topology system that are topologically protected. Thus, research in Guan Tapu photonics has revealed a variety of promising applications such as back-scattering immune waveguides, topological frequency division multiplexing, topological cross-channels, and large area waveguide states.
In recent years, many topologies have been extended from electronic systems to classical wave systems and implemented in photonic crystal (PhC) systems in a controlled manner. Generally, the symmetry is reversed in graphene-like PhC by breaking the space of the lattice, such that a Dirac point with a pair of degenerates is opened, forming a non-trivial band gap. Boundary states in the band gap appear at the interface (domain wall) between topologies with opposite valley Chern numbers, exhibiting valley locking and immunity transmission characteristics, referred to as Gu Niujie states (valley boundary states). Due to its topologically protected nature, inter-valley scattering can be suppressed, resulting in Gu Guangzi crystals showing promising applications in on-chip communications, topological energy concentrators and topological lasers. However, recent studies have revealed a new class of topologically chiral boundary states at the outer boundary of PhC, where the existence of topologically chiral boundary states is demonstrated by manipulation of boundary potential. Furthermore, chiral boundary states are self-guiding and do not rely on cladding to prevent radiation leakage of electromagnetic energy. Chiral boundary states occur at the outer boundaries of the PhC compared to the valley kink states that rely on domain walls or inner boundaries, making it easier to achieve a robust and miniaturized topological electromagnetic device.
The substrate integrated topological waveguide exhibits the advantage of being compatible with standard substrate integrated waveguide circuits as compared to previous topological valley photonic crystal (PhC) waveguides. Therefore, the proposal of the substrate integrated topological waveguide opens up a new approach for freely manipulating topological boundary states in the substrate integrated photonic circuit. However, there is a need to design metal vias or metal pillar structures in the research of substrate integrated topology waveguides; when the size is small, the precision is difficult to ensure, so that the machining difficulty is increased, the manufacturing cost is increased, and the application is limited to a great extent. In addition, when the transmission of chiral boundary states is researched, a point source is usually used as an excitation source, the coupling efficiency from the source to the topological boundary states is extremely low, the loss is very high, and the problem of low overall transmission efficiency in a topological PhC system is caused.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention provides a substrate integrated topological waveguide based on chiral boundary states, which has the advantages of high coupling efficiency, low loss, miniaturization and easiness in manufacturing.
The technical aim of the invention is realized by the following technical scheme:
a substrate integrated topological waveguide based on chiral boundary states comprises an upper metal film layer, a dielectric substrate F4B, a lower metal layer and a microstrip transmission line;
the interfaces at two sides of the substrate integrated topological waveguide are respectively set into an A-type interface and a B-type interface, the boundaries of the A-type interface and the B-type interface are saw-tooth-shaped, the boundary between the boundary and air at two sides is respectively set into a waveguide channel 1 and a waveguide channel 2, the waveguide channel 1 and the waveguide channel 2 are used for supporting the transmission of chiral boundary states, and the transmission directions of the chiral boundary states transmitted by the waveguide channel 1 and the waveguide channel 2 at a unified frequency are opposite; the upper metal film layer is provided with a plurality of combined air holes, and the combined air holes are formed by connecting three Y-shaped air holes. .
The invention is further provided with: the three Y-shaped air holes of the combined air holes in the body area have the same size, and the adjacent Y-shaped air holes are connected through air slits, and the Y-shaped air holes in the combined air holes close to the boundary are different from the Y-shaped air holes in the body area in size.
The invention is further provided with: the length of the primitive cell Y-shaped air hole in the body domain is l=1.5 mm, and the width is w=0.5 mm; the length of the Y-shaped air hole of the A-shaped interface primitive cell close to the waveguide channel 1 is l 1 =0.7 mm, width w 1 The length of the Y-shaped air hole of the b-shaped interface primitive cell close to the waveguide channel 2 is l =0.9mm 2 =0.6 mm, width w 2 ＝0.9mm。
The invention is further provided with: the thickness of the dielectric substrate F4B is t=1 mm, and the dielectric constant is 2.65.
The invention is further provided with: the microstrip transmission line comprises a conical gradual change part, the impedance of the microstrip transmission line is set to be 50Ω, and triangular transition structures are adopted at the initial end parts of the waveguide channel 1 and the waveguide channel 2.
The invention is further provided with: the upper metal film layer is made of copper.
The invention is further provided with: the Y-shaped air hole is provided with C 3 Symmetry, which breaks C in momentum space 3v Symmetry opens up a pair of degenerate Dirac points originally at the K and K 'valleys, the photonic band gap appearing in the photonic crystal's band structure.
By analyzing the distribution characteristics of electromagnetic modes and energy flows of a topological waveguide structure, a conical gradual change microstrip transmission line with 50 omega impedance is designed to match the impedance at the interface of the transmission line and a waveguide channel, and the traditional guided wave mode is smoothly transited to a chiral boundary state; efficient conversion from conventional guided wave mode to topology mode is achieved. In addition, when the topological waveguide interface is bent, the chiral boundary state can be smoothly transmitted forward through the bent interface, and smooth transition between boundary states can be realized. I.e., when an electromagnetic signal is input from port1 of the waveguide channel, the electromagnetic signal can be robustly transmitted to port2. Therefore, the topology waveguide interface facing disturbance (different types of bending interfaces) and non-disturbance (straight-through) has the characteristics of low loss and high transmission efficiency.
The invention has the following advantages:
1. the structure design is novel, compatible with standard Printed Circuit Board (PCB) technology, can be conveniently combined with a feed network and a planar circuit, and is easy to manufacture, miniaturized, light in weight and low in cost. The substrate integrated waveguide structure is ensured to have the characteristics of high efficiency, low loss, reliable mechanical and electromagnetic performance and the like.
2. Because the electromagnetic signals are transmitted on two different types of interfaces, the electromagnetic signals can be transmitted at the interface of the topological waveguide in a good constraint way, the topological structure can reduce the scattering of the electromagnetic signals into the photonic crystal, reduce electromagnetic mutual coupling and crosstalk caused by double-channel transmission, and improve the transmission efficiency of the waveguide; no inter-valley scattering exists, and high-efficiency and stable transmission can be realized for different types of bending interfaces.
3. In a communication system, the substrate integrated topological waveguide can be integrated with various passive and active devices to a platform, so that self-guided transmission of electromagnetic signals along a PhC and air interface is realized, and the substrate integrated topological waveguide has a great application prospect in the aspects of exploring novel physical phenomena of topological chiral boundary states and the like.
Drawings
FIG. 1 is a schematic diagram of a substrate integrated topology waveguide based on chiral boundary states and its structural dimensions in an embodiment of the present invention;
FIG. 2 shows two types of boundaries and their projected energy bands composed of PhC and air in an embodiment of the present invention; the shaded areas in the band diagram are bulk states, and the circular and square dotted lines within the band gap range represent chiral boundary states generated by the PhC upper boundary (type a interface) and lower boundary (type B interface). The left and right panels show the structural schematic and energy flow (arrows indicate directions) of the type B interface and the type a interface, respectively.
FIG. 3 is a schematic diagram of the electric field intensity distribution and S-parameters in a topological electromagnetic waveguide at a frequency of 13GHz in an embodiment of the invention; FIGS. 3 (a) and 3 (c) illustrate the electric field E when an electromagnetic signal is input from port1 along the type A interface of a topological electromagnetic waveguide z Distribution and S parameters. FIGS. 3 (B) and 3 (d) illustrate the electric field E when an electromagnetic signal is input from port3 along the B-type interface of a topological electromagnetic waveguide z Distribution and S parameters;
FIG. 4 shows the transmission characteristics of chiral boundaries in a curved interface comprising a type A interface and a type B interface according to an embodiment of the present invention; fig. 4 (a) shows a schematic diagram of a folded interface consisting of two types of boundaries, wherein the two types of transmission channels are denoted by waveguide Channel 1 (Channel 1) and waveguide Channel 2 (Channel 2), respectively; FIGS. 4 (b) and 4 (c) show the electric field strength E of an electromagnetic signal smoothly transitioning from waveguide channel 1 to waveguide channel 2 when it is input from port1 z Distribution and S parameters.
FIG. 5 shows the present inventionIn the embodiment, the transmission characteristic of the Z-shaped topological waveguide channel from the chiral boundary state to the valley kink state is that; fig. 5 (a) shows a schematic structure of a zigzag topology waveguide channel, wherein a dotted line is a waveguide channel 2 supporting chiral boundary state transmission, and a solid line is a waveguide channel 3 supporting Gu Niujie state transmission. Fig. 5 (c) shows dispersion curves corresponding to type a and type B interfaces. FIGS. 5 (b) and 5 (d) show that when an electromagnetic signal is input from port1, the chiral boundary state transmitted from waveguide channel 2 smoothly transitions to the kink-state electric field strength E transmitted in waveguide channel 3 z Distribution and S parameters.
Fig. 6 shows a transmission characteristic of a Gu Niujie-state chiral boundary state zigzag topology waveguide channel according to an embodiment of the present invention. Fig. 6 (a) shows a schematic structure of a zigzag topology waveguide channel, wherein a solid line is a waveguide channel 1 supporting chiral boundary state transmission, and a solid line is a waveguide channel 3 supporting Gu Niujie state transmission. Fig. 6 (c) shows dispersion curves corresponding to type a and type B interfaces. FIGS. 6 (b) and 6 (d) show that when an electromagnetic signal is input from the port1, the valley twist state transmitted from the waveguide channel 3 smoothly transits to the chiral boundary state electric field intensity E transmitted in the waveguide channel 1 z Distribution and S parameters.
Detailed Description
The technical scheme of the invention is further described below with reference to the accompanying drawings and examples.
A substrate integrated topological waveguide based on chiral boundary states, as shown in figure 1, comprises a copper upper metal film layer (35 mu m thick) with patterns, a dielectric substrate F4B, a lower metal layer and a microstrip transmission line. The thickness of the F4B dielectric substrate was t=1 mm, and the dielectric constant was 2.65. The pattern is that the primary cells in the body domain are provided with combined air holes, the combined air holes are specifically three mutually connected Y-shaped air holes, adjacent air holes are connected through air slits, the length of the Y-shaped air holes is l=1.5 mm, and the width of the Y-shaped air holes is w=0.5 mm; y-shaped air hole pattern having C 3 Symmetry, which breaks C in momentum space 3v Symmetry causes a pair of degenerate Dirac points, originally at the K and K 'valleys, to be opened and a photonic band gap to appear in the photonic crystal's band structure. Realizing chiral boundary states by changing boundary potential in substrate integrated topology waveguideThe boundary potential can be regulated and controlled by changing the structural size of boundary cells. The chiral boundary state is mainly positioned at the interface of PhC and air, the field of the chiral boundary state is rapidly attenuated in the body, and 4 cells are taken in the body to sufficiently reflect the photon forbidden band characteristic.
The interfaces at two sides of the substrate integrated topological waveguide are respectively set into an A-type interface and a B-type interface, the boundaries of the A-type interface and the B-type interface are saw-tooth-shaped, the boundary between the two sides and air is respectively set into a waveguide channel 1 and a waveguide channel 2, the waveguide channel 1 and the waveguide channel 2 are used for supporting the transmission of chiral boundary states, the transmission directions of the chiral boundary states transmitted by the waveguide channel 1 and the waveguide channel 2 at the unified frequency are opposite, and the two sides of the waveguide channel 1 and the waveguide channel 2 are connected with feed and transition structures and are positioned at the starting ends of the topological waveguide structures. The input source end adopts microstrip line feed with characteristic impedance of 50Ω, and adopts taper gradual change structure to realize connection and conversion of microstrip mode and chiral boundary state, wherein the microstrip transmission line has size of W 0 ＝2.7mm，w 3 ＝0.775mm,W 4 ＝6.2mm,L 3 =13.8mm. The length of the Y-shaped air hole of the A-shaped interface primitive cell close to the waveguide channel 1 is l 1 =0.7 mm, width w 1 The length of the Y-shaped air hole of the b-shaped interface primitive cell close to the waveguide channel 2 is l =0.9mm 2 =0.6 mm, width w 2 =0.9 mm. The elementary cells are arranged according to a triangular lattice to form a substrate integrated topological waveguide without metal through holes in the medium, and the lattice constant a=13 mm. The traditional coupling effect of the guided wave mode and the chiral boundary state is utilized to realize the chiral boundary state with low loss and higher transmission efficiency. And the whole waveguide structure is manufactured by adopting the PCB printing technology, the laser cutting technology and the like, and the processing technology is convenient and easy to manufacture. Meets the impedance matching condition, and has the characteristics of low loss, miniaturization and easy integration.
By analyzing the nature of chiral boundary states of the A-type interface and the B-type interface in the band gap range through energy bands, the frequency range corresponding to the boundary states of the A-type interface and the B-type interface can be regulated and controlled by controlling the structural sizes of the primordia at two sides. Therefore, the A-type interface or the B-type interface can be further controlled by controlling the frequency range of the boundary state of the A-type interface or the B-type interfaceTransmission paths and frequency ranges for boundary states. In FIG. 5, transmission of B-type boundary states is achieved by reducing the frequency range of A-type interface boundary states, the size of the A-type and B-type interface primordia being l 1 ＝1.25mm,l 2 =0.6 mm; in FIG. 6, transmission of the type A boundary state is achieved by decreasing the frequency range of the type B boundary state, where the dimensions of the type A and type B boundary cells are l 1 ＝0.7mm,l 2 =1.2mm; the topology mode at the same frequency is found to have opposite transmission characteristics by analyzing the energy flows of the A-type interface and the B-type interface, and the chiral boundary state is stably propagated at the zigzag interface; the smooth transition between the chiral boundary state and the Gu Niujie state can be realized by switching the positions of the A-type interface and the B-type interface along the upper and lower directions and creating an internal domain wall in the bulk domain.
Fig. 2 shows chiral boundary states existing at the a-type interface and the B-type interface, taking y=0 as a boundary standard, taking 2 cells along the + -y (up and down) directions respectively, placing the a-type interface cells and the B-type interface cells together, and calculating projections of zigzag interfaces formed by the a-type interface cells, the B-type interface cells and air along the x direction by using a supercell calculation method to determine the chiral boundary states. The hatched area represents the body band, and the circular dotted line and the directional dotted line represent the band structures of the chiral boundary states transmitted by the a-type interface and the B-type interface, respectively. In order to more visually represent chiral boundary states on the A-type interface and the B-type interface, the left panel and the right panel respectively show supercell schematic diagrams of the two interfaces and energy flow distribution at corresponding frequencies (positive triangle and negative triangle), the arrow represents the Poynting power flow direction, and the field is mainly concentrated in a zigzag interface contacted with air and attenuated into a body. In the dispersion relation of boundary states, it can be seen that the group velocities of chiral boundary states located at the same frequency of the type a and type B interfaces within the band gap exhibit chiral characteristics in exact opposition.
In order to intuitively describe the transmission characteristics of electromagnetic signals, the S-parameter curve of the proposed substrate integrated topological waveguide and the electric field intensity E of the electromagnetic signals when the electromagnetic signals are input along different ports are simulated by using the numerical value of a commercial software CST microwave working chamber z The distribution, the working principle and the transmission characteristics of which are more clearly shown in figures 3 to 6, wherein the arrow tableThe directions of electromagnetic signal input and output are shown. The two terminals of the microstrip structure with the tapered transition section constitute two ports port1 and port2. The propagation of chiral boundary states at type a and type B interfaces is here focused on.
FIG. 3 shows the electric field strength E of the whole waveguide when electromagnetic waves are input from port1 and port3, respectively z Distribution and variation of S parameters. By analyzing the distribution and polarization characteristics of the electromagnetic field in the waveguide channel and combining the field distribution of the tapered graded transmission line to determine the position of the boundary feed point, a triangular transition structure (graded filling is carried out on part of the Y-shaped air holes as shown in figure 1) is adopted at the initial end part of the waveguide channel, so that the smooth conversion of the electromagnetic mode is realized. FIGS. 3 (a) and 3 (b) show the electric field strength E in the entire waveguide z The electromagnetic energy is tightly bound at the zigzag boundary of the type a and type B interfaces that are in contact with air. Electromagnetic signals input from port1 and port3 can well transition a guided wave mode to a chiral boundary state through conical gradual change, and most of electromagnetic signals can well be transmitted to port2 and port4 along an interface; as can be seen from the S-parameter curves in fig. 3 (c) and 3 (d), the transmission of chiral boundary states has good consistency with the analysis of the dispersion curve in the band in the frequency range corresponding to each boundary state in the band gap; the transmission coefficient S in FIG. 3 (c) 21 Slightly lower than the transmission coefficient S in FIG. 3 (d) 34 This is mainly caused by the different mode profile and wave vector differences between the chiral boundary states of the transmission line mode and the a-interface. However, the entire substrate integrated topology waveguide still has the excellent characteristics of low insertion loss and higher efficiency transmission.
The largest feature of topological waveguides is immunity to imperfections, with insensitive features to disturbances. To verify the immunity of the proposed substrate integrated topology waveguide to structural disturbances, we introduce three different types of folded interfaces in fig. 4-6. The first is to introduce A, B waveguide channels of two structural types into the interface of the topological waveguide to realize the conversion of two chiral boundary states; the second is that the topological waveguide interface is a bending channel with a 120-degree corner, so that the smooth transition between the chiral boundary state and the Gu Niujie state is realized. And thirdly, the interface of the topological waveguide is converted into a Z-shaped channel with a 60-degree corner, so that smooth transition between the valley twist state and the chiral boundary state is realized. It can be seen from the figure that the chiral boundary states transmitted in the topological waveguide can smoothly continue to propagate forward through different types of bending interfaces.
Fig. 4 (a) shows a first waveguide channel consisting of a type a interface and a type B interface, the waveguide interface consisting of three boundary surfaces and bends having 120 ° and 60 °. FIGS. 4 (b) and 4 (c) show the electric field strength E transmitted along the bending interface in the chiral boundary state waveguide channel z Distribution and S parameters. The electromagnetic signals input from the port1 can be smoothly bent under the condition of uniform distribution of the external boundary, so that effective conversion of two chiral boundary states is realized; the transfer curve is almost the same as the transfer curve previously input from port1 in fig. 3 (c), revealing a key feature of the topological chiral boundary state.
Fig. 5 (a) shows a second waveguide channel 2 and 3 consisting of a type B interface and domain walls between two domains of non-uniform topology, both channels having bends with 120 ° corners, the upper and lower boundary surfaces of the waveguide consisting of an a (solid line box), B (dashed line box) interface. Fig. 5 (c) shows dispersion curves for type a and type B interfaces, for which the dispersion curve corresponds to a very narrow frequency range and is close to the bulk band, whereas for type B interfaces the dispersion curve extends through the entire band gap. Thus, chiral boundary states propagating along the B-type interface exhibit forbidden behavior at the a-type interface. FIG. 5 (b) shows the electric field strength E at 14GHz (inverted triangle) when an electromagnetic signal is input from port1 z Distribution. It can be seen that little energy is coupled to the a-type interface but is transferred along waveguide channel 3 and waveguide channel 2 to port2, no scattering occurs at the interface kink, and a smooth transition between chiral boundary states and valley kink states is achieved. Fig. 5 (d) shows an S-parameter transmission curve whose transmission range coincides with the dispersion characteristic in fig. 5 (b).
FIG. 6 (a) shows a third waveguide channel 3 and waveguide channel 1 consisting of an internal boundary (domain wall) between two domains of non-trivial topology and an A-type interface, both channels having bends with a 60 degree turn, the lower boundary surface of the waveguide being defined by A (realWire frame), B (dashed frame). The smooth transition between the valley kink state and the chiral boundary state is realized. Fig. 6 (c) shows dispersion curves of a type interface and a type B interface, for which the dispersion curve is divided into an upper part and a lower part. The lower part is positioned in a narrow corresponding frequency range and is close to the body band; the upper part has a frequency range between 13.6 and 14.5 GHz. However, for type a interfaces, the dispersion curve lies between 12.8 and 14.1 GHz. Thus, chiral boundary states transmitted along the type a interface exhibit forbidden behavior at the type B interface for frequencies in the range of 12.8-13.6 GHz. FIG. 6 (b) shows the electric field strength E at 13.5GHz (right triangle) when an electromagnetic signal is input from port1 z Distribution. It can be seen that little energy is coupled to the B-type interface but is transferred along waveguide channel 3 and waveguide channel 1 to port2, enabling a smooth transition from the kink state to the chiral boundary state. Fig. 6 (d) shows an S-parameter transmission curve whose transmission frequency range coincides with the dispersion characteristic in fig. 6 (b).
It can be seen that the transmission characteristics in the three different cases are not significantly changed compared to the non-perturbed (straight-through) one in fig. 1, revealing the inherent robustness of the topological chiral boundary states to the kinked interface. Therefore, the electromagnetic signals input from the ports can realize different types of chiral boundary states and conversion and transition between the chiral boundary states and the valley kink states according to the expected design, so that most of the electromagnetic signals can be output from the appointed ports; even if disturbance electromagnetic signals exist in the topological waveguide, low-loss and high-efficiency transmission can be realized.
The substrate integrated topological waveguide based on the chiral boundary state, provided by the embodiment of the invention, is based on accurate regulation and control of boundary potential, and realizes the transmission of the robust chiral boundary state of the external sawtooth boundary of the substrate integrated PhC. By adjusting the boundary structure, the group velocity and the frequency range of the chiral boundary state can be flexibly regulated and controlled. The microstrip transmission line with the conical gradual change structure is used as an initial feeder line, so that the return loss of chiral boundary states in a waveguide channel is reduced, and the transmission efficiency is improved, so that the microstrip transmission line is closer to the characteristics of integration and the like in practical application. By simulating the electric field and the S parameter, the transmission characteristics of the chiral boundary state, the steady transmission through the bending interface and the steady transition between the chiral boundary state and the valley kink state are displayed. Such self-guiding chiral boundary states do not rely on internal boundaries or cladding to prevent energy radiation, which is more compact than electromagnetic devices based on the valley twist state. The substrate integrated topological waveguide based on the chiral boundary state has important application prospects in millimeter wave, terahertz wave and optical frequency bands, and comprises passive, active or other planar devices, such as a robust delay line, an on-chip communication and topological laser, and the like. Through example verification, under different disturbance (bending), when electromagnetic signals are input from different ports, good transmission characteristics are shown, and the characteristics of no back scattering, robustness to disturbance, high transmission efficiency, small loss and the like of the proposed substrate integrated topological waveguide structure are demonstrated. Furthermore, compared to previous valley topology waveguides, the proposed chiral boundary state based topology waveguide not only has higher transmission efficiency but also exhibits sub-wavelength thickness, ease of design and excellent self-consistent electrical shielding, which is perfectly compatible with conventional substrate integrated waveguide circuits. The present design provides the possibility to manufacture and integrate a complete topological waveguide circuit on the same substrate using standard printed circuit board technology. And can be used as a design choice with low cost, miniaturization, light weight and easy integration.
Finally, it is noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the technical solution of the present invention, which is intended to be covered by the scope of the claims of the present invention.
Claims (7)
1. A substrate integrated topological waveguide based on chiral boundary states is characterized in that: the micro-strip transmission line comprises an upper metal film layer, a dielectric substrate F4B, a lower metal layer and a micro-strip transmission line;
the interfaces at two sides of the substrate integrated topological waveguide are respectively set into an A-type interface and a B-type interface, the boundaries of the A-type interface and the B-type interface are saw-tooth-shaped, the boundary between the boundary and air at two sides is respectively set into a waveguide channel 1 and a waveguide channel 2, the waveguide channel 1 and the waveguide channel 2 are used for supporting the transmission of chiral boundary states, and the transmission directions of the chiral boundary states transmitted by the waveguide channel 1 and the waveguide channel 2 at a unified frequency are opposite; the upper metal film layer is provided with a plurality of combined air holes, and the combined air holes are formed by connecting three Y-shaped air holes.
2. A chiral boundary state based substrate integrated topology waveguide of claim 1, wherein: the three Y-shaped air holes of the combined air holes in the body area have the same size, and the adjacent Y-shaped air holes are connected through air slits, and the Y-shaped air holes in the combined air holes close to the boundary are different from the Y-shaped air holes in the body area in size.
3. A chiral boundary state based substrate integrated topology waveguide as recited in claim 2, wherein: the length of the primitive cell Y-shaped air hole in the body domain is l=1.5 mm, and the width is w=0.5 mm; the length of the Y-shaped air hole of the A-shaped interface primitive cell close to the waveguide channel 1 is l 1 =0.7 mm, width w 1 The length of the Y-shaped air hole of the b-shaped interface primitive cell close to the waveguide channel 2 is l =0.9mm 2 =0.6 mm, width w 2 ＝0.9mm。
4. A chiral boundary state based substrate integrated topology waveguide of claim 3, wherein: the thickness of the dielectric substrate F4B is t=1 mm, and the dielectric constant is 2.65.
5. The substrate integrated topology waveguide of claim 4, wherein the substrate integrated topology waveguide is based on chiral boundary states, wherein: the microstrip transmission line comprises a conical gradual change part, the impedance of the microstrip transmission line is set to be 50Ω, and triangular transition structures are adopted at the initial end parts of the waveguide channel 1 and the waveguide channel 2.
6. The substrate integrated topology waveguide of claim 5, wherein the substrate integrated topology waveguide is based on chiral boundary states, wherein: the upper metal film layer is made of copper.
7. The substrate integrated topology waveguide of claim 6, wherein the substrate integrated topology waveguide is based on chiral boundary states: the Y-shaped air hole is provided with C 3 Symmetry, which breaks C in momentum space 3v Symmetry opens up a pair of degenerate Dirac points originally at the K and K 'valleys, the photonic band gap appearing in the photonic crystal's band structure.
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