Terahertz waveguide energy beam splitter

Abstract

The utility model discloses a terahertz waveguide energy beam splitter, which belongs to the technical field of terahertz waveguide energy transmission and comprises an upper metal plate, a lower metal plate and a valley photonic crystal array structure positioned between the upper metal plate and the lower metal plate. The valley photonic crystal array structure comprises a first area, a second area, a third area and a fourth area, the first area and the fourth area are adjacent to the second area and the third area respectively, and a first air channel, a second air channel, a third air channel and a fourth air channel are formed. The first area and the fourth area comprise a plurality of first valley photonic crystals, and the second area and the fourth area comprise a plurality of second valley photonic crystals. Compared with an existing terahertz energy beam splitter, the terahertz energy beam splitter overcomes ohmic loss and solves the scattering problem caused by dielectric waveguide bending loss and defects, so that the transmission efficiency is improved, a transmitted topological waveguide state has certain topological protection capacity, and the terahertz energy beam splitter has good anti-scattering capacity.

Description

Technical Field

[0001] This utility model relates to the field of terahertz waveguide energy transmission technology, specifically to a terahertz waveguide energy beam splitter. Background Technology

[0002] Photonic crystals are artificial materials that control light propagation through periodic dielectric structures, and their bandgap properties can be used to design efficient waveguides. Traditional photonic crystal waveguides guide light propagation by introducing line defects into the periodic structure, but their performance is susceptible to manufacturing defects, structural perturbations, or bending, leading to significant backscattering and transmission loss. This sensitivity limits their application in integrated photonic devices, especially in high-density integration and complex path designs. Drawing inspiration from the concept of topological insulators in condensed matter systems, topology has been rapidly developed in recent years by introducing topology into electromagnetic systems. In topological photonic systems, there are mainly topological photonic crystals analogous to the quantum Hall effect (QHE), quantum spin Hall effect (QSHE), and quantum valley effect (QVHE). In 2008, Haldane and Raghu first introduced topological phase transition theory into photonics, proposing a theoretical framework for photonic topological insulators. By introducing a magnetic field to break time-reversal symmetry, they realized Chern insulators, whose bulk states are insulating while their boundaries support unidirectional transmission topological boundary states. Subsequently, the researchers explored topological boundary states that achieve spin and valley polarization without the need for an external magnetic field by breaking spatial inversion symmetry.

[0003] For traditional terahertz devices, most transmission devices are still based on microwave devices, such as microstrip lines, coplanar waveguides, hollow waveguides, and substrate-integrated waveguides. However, in the terahertz optical band, metals have relatively high losses. In order to reduce ohmic losses, researchers have designed terahertz waveguide devices using all-dielectric materials. However, terahertz waves generate large reflection losses at sharp bends in the devices, which limits the miniaturization of terahertz optical devices and the integration of functional components.

[0004] Terahertz energy beamsplitters distribute incident terahertz waves along different paths in a specific ratio, enabling signal distribution, multi-channel detection, or interferometric measurements. They are key components for constructing complex terahertz systems. However, beamsplitters based on conventional photonic crystals (such as silicon and quartz) suffer from high absorption loss and low beam splitting efficiency in the terahertz band, and are also susceptible to disturbances (such as bending and structural defects). Utility Model Content

[0005] The purpose of this invention is to provide a terahertz waveguide energy beam splitter to solve the problems of high absorption loss, low beam splitting efficiency, and susceptibility to disturbances (such as bending and structural defects) in existing terahertz energy beam splitters.

[0006] The technical solution of this utility model to solve the above-mentioned technical problems is as follows:

[0007] A terahertz waveguide energy beam splitter includes: an upper metal plate, a lower metal plate, and a valley photonic crystal array structure located between the upper metal plate and the lower metal plate;

[0008] The valley photonic crystal array structure includes a first region, a second region, a third region, and a fourth region. The first region and the fourth region are adjacent to the second region and the third region, respectively, so that a first air channel is formed between the first region and the third region, a second air channel is formed between the first region and the second region, a third air channel is formed between the third region and the fourth region, and a fourth air channel is formed between the second region and the fourth region.

[0009] The first and fourth regions include several first-valley photonic crystals, and the second and third regions include several second-valley photonic crystals.

[0010] Furthermore, the lattice constant of the above-mentioned valley photonic crystal array structure is a = 300 μm, the background material is air, and its relative permittivity is 1.

[0011] Furthermore, both the first valley photonic crystal and the second valley photonic crystal are composed of dielectric pillars A and B arranged in an alternating honeycomb structure.

[0012] Furthermore, in the first valley photonic crystal, the diameter of dielectric pillar A is larger than the diameter of dielectric pillar B, while in the second valley photonic crystal, the diameter of dielectric pillar A is smaller than the diameter of dielectric pillar B.

[0013] Furthermore, in the first valley photonic crystal, the diameter of dielectric pillar A is 0.3a and the diameter of dielectric pillar B is 0.2a; in the second valley photonic crystal, the diameter of dielectric pillar A is 0.2a and the diameter of dielectric pillar B is 0.3a.

[0014] Furthermore, the height of each of the above-mentioned medium columns is 100 μm.

[0015] Furthermore, both dielectric pillar A and dielectric pillar B are made of silicon, with a relative permittivity of 11.7.

[0016] Furthermore, the angle between the first air channel and the second and third air channels is 60°, and the extension direction of the first air channel and the fourth air channel is consistent.

[0017] Furthermore, the width of each of the above air channels .

[0018] This utility model has the following beneficial effects:

[0019] (1) This utility model provides a terahertz waveguide energy beam splitter based on a line defect topological valley photonic crystal structure. Compared with existing terahertz energy beam splitters, it overcomes the ohmic loss of traditional terahertz metal waveguides, solves the bending loss of dielectric waveguides and the scattering problem caused by defects, thereby improving the efficiency of terahertz wave energy transmission. The topological waveguide state transmitted in the topological channel has a certain topological protection capability and has a good anti-scattering capability.

[0020] (2) The present invention proposes a terahertz waveguide energy beam splitter based on a valley topological photonic crystal structure with a line defect. The valley topological photonic crystal and the air channel are used to construct a heterogeneous structure with a line defect. The electromagnetic energy is mainly confined in the air channel. The transmission characteristics are maintained during the transmission process. The waveguide can be smoothly transmitted at the bends. It has strong robustness. Within a certain operating frequency range, when the electromagnetic wave is input from the port, it can be transmitted unidirectionally along the predetermined channel. It has the characteristics of low loss, anti-interference, simple structure, easy design, and miniaturization. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the terahertz waveguide energy beam splitter of this utility model;

[0022] Figure 2 This is a schematic diagram of the structure of the novel valley photonic crystal array, where A represents dielectric pillar A and B represents dielectric pillar B.

[0023] Figure 3 This diagram shows the cell structure and band structure of the first valley photonic crystal (VPC1) of this invention, where A represents dielectric pillar A and B represents dielectric pillar B. Figure 3 (a) shows the cell structure of the first valley photonic crystal (VPC1). Figure 3 (b) shows the energy band diagram of the unit cell of the first valley photonic crystal (VPC1);

[0024] Figure 4 This diagram shows the cell structure and band structure of the second valley photonic crystal (VPC2) of this invention, where A represents dielectric pillar A and B represents dielectric pillar B. Figure 4 (a) shows the cell structure of the second valley photonic crystal (VPC2). Figure 4 (b) shows the energy band diagram of the unit cell of the second valley photonic crystal (VPC2);

[0025] Figure 5 This invention relates to the supercell structure and dispersion curve of a line-defect valley photonic crystal, wherein... Figure 5 In the middle (a), the structure is a supercell. Figure 5 (b) shows the band structure of the supercell. Figure 5In the middle (c), the field distribution corresponding to the eigenstate with a frequency of 0.37 THz is shown.

[0026] Figure 6 The distribution of the transmission electric field modulus of a TM mode terahertz wave with a frequency of 0.37 THz is shown.

[0027] Figure 7 The transmittance curves are for ports Port1 through Port2 and Port3.

[0028] In the diagram: 1-Upper metal plate; 2-Lower metal plate; 3-Dielectric column A; 4-Dielectric column B; 5-First region; 6-Second region; 7-Third region; 8-Fourth region; 9-First air channel; 10-Second air channel; 11-Third air channel; 12-Fourth air channel. Detailed Implementation

[0029] The principles and features of this utility model are described below with reference to the accompanying drawings. The examples given are only for explaining this utility model and are not intended to limit the scope of this utility model.

[0030] like Figure 1 and Figure 2 As shown, this embodiment provides a terahertz waveguide energy beam splitter, including: an upper metal plate 1, a lower metal plate 2, and a valley photonic crystal array structure located between the upper metal plate 1 and the lower metal plate 2. The valley photonic array structure includes a first region 5, a second region 6, a third region 7, and a fourth region 8. The first region 5 and the fourth region 8 are adjacent to the second region 6 and the third region 7, respectively, thereby forming a first air channel 9, a second air channel 10, a third air channel 11, and a fourth air channel 12. Specifically, the first air channel 9 is formed between the first region 5 and the third region 7, the second air channel 10 is formed between the first region 5 and the second region 6, the third air channel 11 is formed between the third region 7 and the fourth region 8, and the fourth air channel 12 is formed between the second region 6 and the fourth region 8. The first air channel 9, the second air channel 10, the third air channel 11, and the fourth air channel 12 correspond to four ports, Port1, Port2, Port3, and Port4, respectively.

[0031] The valley photonic crystal array structure has a lattice constant a = 300 μm, and the background material is air with a relative permittivity of 1. The valley photonic crystal array structure includes several first valley photonic crystals and second valley photonic crystals. Specifically, the first region 5 and the fourth region 8 include several first valley photonic crystals, and the second region 6 and the third region 7 include several second valley photonic crystals. Both the first and second valley photonic crystals are arranged in a honeycomb structure by alternating dielectric pillars A3 and B4, with the ends of dielectric pillars A3 and A4 connected to the upper metal plate 1 and the lower metal plate 2, respectively.

[0032] In the first valley photonic crystal, the diameter of the dielectric pillar A3 is... Larger than the diameter of medium column B4 That is, the diameter of medium column A3 Diameter of medium column B4 difference In the second valley photonic crystal, the diameter of the dielectric pillar A3 is... Smaller than the diameter of dielectric column B4, i.e., the diameter of dielectric column A3. Diameter of medium column B4 difference .

[0033] In this embodiment, in the first valley photonic crystal, the diameter of dielectric pillar A3 is 0.3a, and the diameter of dielectric pillar B4 is 0.2a. In the second valley photonic crystal, the diameter of dielectric pillar A3 is 0.2a, and the diameter of dielectric pillar B4 is 0.3a. The height of both dielectric pillars A3 and A4 is 100μm. In this embodiment, both dielectric pillars A3 and B4 are made of silicon, with a relative permittivity of 11.7.

[0034] In this embodiment, the angle between the first air channel 9 and the second air channel 10 and the third air channel 11 is 60°. The first air channel 9 and the fourth air channel 12 extend in the same direction. The width of each air channel is: The first air channel 9, the second air channel 10, and the third air channel 11 are the transmission channels for terahertz wave energy.

[0035] like Figure 3 The diagram shows the cell structure and band structure of the first-valley photonic crystal. A band gap exists between the upper and lower bulk states, with a frequency range of 0.3264 THz-0.3977 THz. The main focus is on the TM mode band gap. Figure 4 The diagram shows the cell structure and band structure of the second valley photonic crystal. Although it has the same band structure as the first valley photonic crystal, they have different topological phases, and the chirality of the corresponding eigenstates at the valleys is exactly opposite.

[0036] like Figure 5 The diagram shows the supercell structure and dispersion curve of the first valley photonic crystal, the air channel, and the second valley photonic crystal in this embodiment. Within the band gap between the upper and lower bulk states, there exists a topological waveguide energy band with a frequency range of 0.3616 THz to 0.3855 THz.

[0037] like Figure 6The figure shows the transmission electric field modulus distribution of a TM mode terahertz wave with a frequency of 0.37 THz. An excitation source is placed near port 1. The excited electromagnetic wave travels along the first air channel 9. At the intersection of the waveguides, the electromagnetic energy is split into two and travels along the second air channel 10 and the third air channel 11, respectively, to ports 2 and 3. However, no energy is transmitted to port 4.

[0038] like Figure 7 The figure shows the transmittance curves from Port1 to Port2 and Port3, where S21 represents the transmittance curve of electromagnetic energy from Port1 to Port2, and S31 represents the transmittance curve of electromagnetic energy from Port1 to Port3. Terahertz waves with frequencies in the range of 0.365THz-0.380THz have high transmission efficiency; within this frequency range, the transmittance coefficient of energy reaching Port2 and Port3 is close to 0.5.

[0039] The terahertz waveguide energy beam splitter proposed in this invention is based on a valley topological photonic crystal structure with line defects. It utilizes a valley topological photonic crystal and an air channel to construct a heterogeneous structure with line defects. Electromagnetic energy is mainly confined in the air channel, maintaining stable transmission characteristics during transmission. It can transmit smoothly at waveguide bends and has strong robustness. Within a certain operating frequency range, when electromagnetic waves are input from the port, they can be transmitted unidirectionally along a predetermined channel. It features low loss, anti-interference, simple structure, easy design, and miniaturization.

[0040] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A terahertz waveguide energy beam splitter, characterized by, include: The upper metal plate (1), the lower metal plate (2), and the valley photonic crystal array structure located between the upper metal plate (1) and the lower metal plate (2); The valley photonic crystal array structure includes a first region (5), a second region (6), a third region (7), and a fourth region (8). The first region (5) and the fourth region (8) are adjacent to the second region (6) and the third region (7), respectively, so that a first air channel (9) is formed between the first region (5) and the third region (7), a second air channel (10) is formed between the first region (5) and the second region (6), a third air channel (11) is formed between the third region (7) and the fourth region (8), and a fourth air channel (12) is formed between the second region (6) and the fourth region (8). The first region (5) and the fourth region (8) include a plurality of first valley photonic crystals, and the second region (6) and the third region (7) include a plurality of second valley photonic crystals.

2. The terahertz waveguide energy beam splitter of claim 1, wherein, The lattice constant of the valley photonic crystal array structure is a = 300 μm, the background material is air, and its relative permittivity is 1.

3. The terahertz waveguide energy beam splitter of claim 2, wherein, Both the first valley photonic crystal and the second valley photonic crystal are composed of alternating dielectric pillars A (3) and dielectric pillars B (4) arranged in a honeycomb structure.

4. The terahertz waveguide energy beam splitter of claim 3, wherein, In the first valley photonic crystal, the diameter of dielectric pillar A (3) is greater than the diameter of dielectric pillar B (4), and in the second valley photonic crystal, the diameter of dielectric pillar A (3) is smaller than the diameter of dielectric pillar B (4).

5. The terahertz waveguide energy beam splitter of claim 4, wherein, In the first valley photonic crystal, the diameter of the dielectric pillar A (3) is 0.3a and the diameter of the dielectric pillar B (4) is 0.2a. In the second valley photonic crystal, the diameter of the dielectric pillar A (3) is 0.2a and the diameter of the dielectric pillar B (4) is 0.3a.

6. The terahertz waveguide energy beam splitter of claim 5, wherein, The height of each medium column is 100 μm.

7. The terahertz waveguide energy beam splitter of claim 3, wherein, Both dielectric pillar A (3) and dielectric pillar B (4) are made of silicon, with a relative permittivity of 11.

7.

8. The terahertz waveguide power splitter of any one of claims 2 to 7, wherein, The angle between the first air channel (9) and the second air channel (10) and the third air channel (11) is 60°, and the extension direction of the first air channel (9) and the fourth air channel (12) is consistent.

9. The terahertz waveguide energy beam splitter of claim 7, wherein, The width of each air passage is d = (√3 / 2 + √3 / 15)a.

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