Two-dimensional closed surface wave photonic crystal structure

Abstract

The present invention provides a two-dimensional closed surface wave photonic crystal structure, including a first metal plate, a second metal plate, a metal column and a defective metal column, wherein the first metal plate and the second metal plate are arranged correspondingly, the metal column is two-dimensionally periodically arranged between the first metal plate and the second metal plate, and the opposite ends of the metal column are respectively in contact with the first metal plate and the second metal plate to form a metal column array; the defective metal column is located in the metal column array, and the height of the defective metal column is less than the height of the surrounding metal columns. Based on the surface wave photonic crystal structure, the present invention can integrate a two-dimensional closed surface wave photonic crystal structure including a surface wave photonic crystal structure and a metal-insulator-metal structure by combining a metal plate, so as to provide a two-dimensional closed surface wave photonic crystal structure with strong anti-interference and high integration.

Description

Technical Field

[0001] The invention belongs to the field of integrated optics and relates to a two-dimensional closed surface wave photonic crystal structure. Background Art

[0002] In 1969, Dr. Miller of Bell Labs proposed the concept of integrated optics. The main research goal of integrated optics is to integrate large-scale free-space optical systems onto the same substrate. Among them, the size of integrated optical devices varies with different frequency bands. For example, the millimeter wave band is generally in the millimeter range, and the terahertz (THz) band is mainly in the micron range. Integrated optical devices have the advantages of low power consumption and small size. At the same time, since they are in a relatively closed environment after integration, they are less affected by external electromagnetic radiation. In the context of integrated circuits being constrained by Moore's Law and limited prospects, optoelectronic technology has shown great advantages: the speed of photons in the integrated optical path is much greater than the speed of electrons in the integrated circuit, and it has a larger information capacity.

[0003] In recent decades, with the rapid development of integrated optical circuit technology, photonic crystals, known as "optical semiconductors", have attracted widespread attention. Photonic crystals are a new type of optical microstructure material whose dielectric constant varies periodically with space. According to their different periodicities in three dimensions, they can be divided into three categories: one-dimensional photonic crystals, two-dimensional photonic crystals, and three-dimensional photonic crystals. Among them, two-dimensional photonic crystals can be further divided into hole-shaped flat-plate photonic crystals, dielectric column photonic crystals, and the current cutting-edge quasi-photonic crystals according to their structural characteristics. Among them, photonic crystals have two major characteristics: photonic bandgap and photon localization. The most fundamental feature is the photonic bandgap.

[0004] In nature, surface plasmons are collective oscillation modes of free electrons and photons formed by the interaction between electromagnetic waves and free electrons on the metal surface. Among them, surface plasmons can only exist at the interface of materials with opposite signs of the real part of the dielectric constant, such as the interface between metal and air. Surface plasmons can be divided into two types: one is the surface plasmon polaritons transmitted on the interface between metal and dielectric, and the other is the localized surface plasmons confined to the surface of metal nanoparticles. In 2004, JB Pendry et al., in order to realize surface plasmon polaritons in the microwave and millimeter wave band, etched periodically arranged air holes in a metal cube to realize the transmission of surface plasmons (Surface Plasmon Polaritons, SPP) in the microwave and millimeter wave band. This structure is called artificial surface plasmon (Spoof Surface Plasmon Polaritons, SSPP). In 2005, Hibbins et al. of the University of Exeter published the experimental research results of SSPP in Science. After that, a large number of studies on SSPP appeared, but in the existing research technology, SSPP is strongly interfered by external factors.

[0005] Therefore, it is necessary to provide a new type of surface wave photonic crystal structure. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a two-dimensional closed surface wave photonic crystal structure for solving the problem in the prior art that artificial surface plasmons are easily disturbed by external factors.

[0007] To achieve the above-mentioned object and other related objects, the present invention provides a two-dimensional closed surface wave photonic crystal structure, wherein the two-dimensional closed surface wave photonic crystal structure comprises:

[0008] A first metal plate and a second metal plate, wherein the first metal plate and the second metal plate are arranged correspondingly;

[0009] Metal pillars, the metal pillars are two-dimensionally periodically arranged between the first metal plate and the second metal plate, and opposite ends of the metal pillars are respectively in contact with the first metal plate and the second metal plate to form a metal pillar array;

[0010] A defective metal column is located in the metal column array, and the height of the defective metal column is smaller than the heights of the surrounding metal columns.

[0011] Optionally, the metal pillars are arranged at equal intervals.

[0012] Optionally, the metal pillars have the same cross-sectional area, and the cross-sectional morphology of the metal pillars includes a circle, a square or an ellipse.

[0013] Optionally, the defective metal pillars are arranged at equal intervals.

[0014] Optionally, the defective metal pillars have the same cross-sectional area, and the cross-sectional morphology of the defective metal pillars includes a circle, a square or an ellipse.

[0015] Optionally, the metal column and the defective metal column have the same cross-sectional morphology.

[0016] Optionally, the metal pillars and the defective metal pillars are arranged at equal intervals.

[0017] Optionally, the defective metal pillars have the same height.

[0018] Optionally, the morphology of the structure surrounded by the defective metal pillars includes one of a straight line, a curved shape and a T-shape.

[0019] Optionally, the first metal plate, the second metal plate, the metal column and the defective metal column are made of the same material, wherein the material includes one of gold metal, silver metal, copper metal and aluminum metal.

[0020] As described above, the two-dimensional closed surface wave photonic crystal structure of the present invention includes a first metal plate, a second metal plate, a metal column and a defective metal column, wherein the first metal plate and the second metal plate are arranged correspondingly, the metal column is two-dimensionally periodically arranged between the first metal plate and the second metal plate, and the opposite ends of the metal column are respectively in contact with the first metal plate and the second metal plate to form a metal column array; the defective metal column is located in the metal column array, and the height of the defective metal column is less than the height of the surrounding metal columns. The present invention forms a surface wave photonic crystal structure through the first metal plate, the metal column and the defective metal column, and on the basis of the surface wave photonic crystal structure, by combining the second metal plate, a two-dimensional closed surface wave photonic crystal structure including the surface wave photonic crystal structure and the metal-insulator-metal structure can be integrated to provide a two-dimensional closed surface wave photonic crystal structure with strong anti-interference and high integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the three-dimensional structure of the surface wave photonic crystal structure in the comparative example of the present invention.

[0022] Figure 2 Display as Figure 1 Schematic diagram of the cross-sectional structure obtained along A-A'.

[0023] Figure 3 Display as Figure 1 Schematic diagram of the waveguide transmission coefficient of the surface wave photonic crystal structure.

[0024] Figure 4 Display as Figure 1 Schematic diagram of the passband corresponding field distribution of the surface wave photonic crystal structure.

[0025] Figure 5 Display as Figure 1 Schematic diagram of the local distribution of the electric field corresponding to the bandgap transmission peak of the surface wave photonic crystal structure.

[0026] Figure 6 Display as Figure 1 Schematic diagram of the dispersion curve of the surface wave photonic crystal structure.

[0027] Figure 7 Shown is a schematic diagram of the three-dimensional structure of a two-dimensional closed surface wave photonic crystal structure in an embodiment of the present invention.

[0028] Figure 8 Display as Figure 7 Schematic diagram of the explosion structure.

[0029] Fig. 9 Display as Figure 7 Schematic diagram of the cross-sectional structure obtained along C-C'.

[0030] Figure 10a to Figure 10c Display as Figure 7 Schematic diagram of the structure of the surface wave photonic crystal structure.

[0031] Fig.11 Display as Figure 7 Schematic diagram of the band waveguide mode of the surface wave photonic crystal structure.

[0032] Fig.12 Display as Figure 7 Schematic diagram of the waveguide transmission coefficient in .

[0033] Fig.13 Display as Figure 7 Schematic diagram of the local distribution of the electric field.

[0034] Component number description

[0035] 100, 10 First Metal Plate

[0036] 200 Second Metal Plate

[0037] 300, 30 Metal Column

[0038] 400, 40 Defective metal column DETAILED DESCRIPTION

[0039] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0040] For example, when describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional view showing the device structure will not be partially enlarged according to the general scale, and the schematic view is only an example, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional space dimensions of length, width and depth should be included.

[0041] For ease of description, spatial relational terms such as "under", "below", "below", "below", "above", "on", etc. may be used herein to describe the relationship of one element or feature shown in the drawings to other elements or features. It will be understood that these spatial relational terms are intended to include other directions of the device in use or operation in addition to the directions depicted in the drawings. In addition, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or there can be one or more intervening layers. As used herein, "between..." means including the end point values.

[0042] In the context of the present application, a structure in which a first feature is described as being "above" a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0043] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and therefore the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0044] like Figure 7 to Figure 9The present embodiment provides a two-dimensional closed surface wave photonic crystal structure, which includes a first metal plate 100, a second metal plate 200, a metal column 300 and a defective metal column 400, wherein the first metal plate 100 and the second metal plate 200 are arranged correspondingly, the metal column 300 is two-dimensionally periodically arranged between the first metal plate 100 and the second metal plate 200, and the opposite ends of the metal column 300 are respectively in contact with the first metal plate 100 and the second metal plate 200 to form a metal column array; the defective metal column 400 is located in the metal column array, and the height h of the defective metal column 400 is less than the height H of the surrounding metal columns 300.

[0045] In this embodiment, the first metal plate 100, the metal column 300 and the defective metal column 400 are formed as follows Figure 10a to Figure 10c The surface wave photonic crystal structure shown in FIG. 1 is formed by combining the second metal plate 200 with the surface wave photonic crystal structure. Figure 7 to Figure 9 , the two-dimensional closed surface wave photonic crystal structure including the surface wave photonic crystal structure and the metal-insulator-metal structure can be integrated to provide a two-dimensional closed surface wave photonic crystal structure with strong anti-interference ability and high integration.

[0046] As an example, the metal pillars 300 are arranged at equal intervals A, but this is not limited to this. The metal pillars 300 can also be arranged at unequal intervals as needed, and no excessive restrictions are made here.

[0047] As an example, the metal pillars 300 have the same cross-sectional area, and the cross-sectional shape of the metal pillars 300 may include a circle, a square, or an ellipse.

[0048] Specifically, the metal pillars 300 in this embodiment have the same cross-sectional area and a circular cross-sectional shape, that is, the metal pillars 300 are cylindrical with the same radius R, but the shape of the metal pillars 300 is not limited thereto. As needed, the metal pillars 300 may also be square, elliptical or any combination of circular, square and elliptical, and the size of the metal pillars 300 is not limited to the same.

[0049] As an example, the defective metal pillars 400 are arranged at equal intervals a (not shown), but this is not limited thereto. The defective metal pillars 400 may also be arranged at unequal intervals as required, and no excessive limitation is made here.

[0050] As an example, the defective metal pillars 400 have the same cross-sectional area, and the cross-sectional morphology of the defective metal pillars 400 may include a circle, a square, or an ellipse.

[0051] Specifically, the defective metal pillars 400 in this embodiment have the same cross-sectional area and a circular cross-sectional shape, that is, the defective metal pillars 400 are cylindrical with the same radius r, but the shape of the defective metal pillars 400 is not limited to this. As needed, the defective metal pillars 400 may also be square, elliptical or any combination of circular, square and elliptical.

[0052] As an example, the metal pillar 300 and the defective metal pillar 400 have the same cross-sectional morphology.

[0053] Specifically, in this embodiment, the metal column 300 and the defective metal column 400 preferably have the same cross-sectional morphology, that is, the radius R of the metal column 300 and the radius r of the defective metal column 400 preferably have the same size, but it is not limited thereto.

[0054] As an example, the metal pillars 300 and the defective metal pillars 400 are arranged at equal intervals.

[0055] Specifically, in this embodiment, the metal pillars 300 and the defective metal pillars 400 are preferably arranged at equal intervals, that is, the interval A between the metal pillars 300 and the interval a between the defective metal pillars 400 are preferably of the same size, and the interval between the metal pillars 300 and the defective metal pillars 400 is also the interval A, but it is not limited to this.

[0056] As an example, the defective metal pillars 400 have the same height h, but it is not limited thereto and can be set as required.

[0057] As an example, the morphology of the structure surrounded by the defective metal pillars 400 includes one of a straight line, a curved shape and a T-shape.

[0058] For details, see Figure 10a to Figure 10c Three surface wave photonic crystal structures in this embodiment are illustrated, wherein: Fig.10a Schematic diagram of a surface wave photonic crystal structure having defective metal pillars 400 distributed in a linear manner. Fig.10b Schematic diagram of a surface wave photonic crystal structure having defective metal pillars 400 distributed in a curved pattern. Fig.10c The surface wave photonic crystal structure having defective metal pillars 400 distributed in a T-shape is illustrated, but the distribution morphology of the defective metal pillars 400 is not limited thereto.

[0059] As an example, the first metal plate 100, the second metal plate 200, the metal column 300 and the defective metal column 400 are made of the same material, wherein the material may include one of gold metal, silver metal, copper metal and aluminum metal. The specific material can be selected according to needs and is not excessively restricted here.

[0060] The following introduces the design of the two-dimensional closed surface wave photonic crystal structure in combination with experiments, wherein the selection of the specific size, morphology, material, etc. of the two-dimensional closed surface wave photonic crystal structure is not limited here, and changes in the working frequency band, dispersion curve and other results caused by changing any geometric parameters fall within the scope of this patent.

[0061] See also Figure 1 to Figure 5 , provide comparative examples and experimental results, including:

[0062] like Figure 1 As shown, a surface wave photonic crystal structure is provided, which is composed of two parts, the lower layer is the first metal 10, and the upper layer is a square array composed of metal pillars 30 (using metal cylinders) and defect pillars 40 (using metal cylinders). When working at 0.1 THz, the spacing A' between the metal pillars 30 is equal to the spacing a' (not shown) between the defect pillars 40, that is, A'=a'=0.5mm, the radius R' of the metal pillar 30 is 0.25A', that is, R'=0.125mm, the height H' of the metal pillar 30 is 0.5mm, the radius r' of the defect pillar 40 is 0.25a', that is, R'=r'=0.125mm, and the height h' of the defect pillar 40 is 0.83H=0.415mm.

[0063] After the defect column 40 is introduced, a photonic crystal waveguide can be constructed according to the photonic bandgap and photon localization characteristics of the photonic crystal. The transmission coefficient of this waveguide is as follows: Figure 3 As shown, the transmission coefficient includes two parts: the passband and the forbidden band. The electric field distribution corresponding to the passband (taking 100 GHz as an example) is as follows: Figure 4 As shown, the electric field distribution corresponding to the bandgap transmission peak (135GHz) is as follows Figure 5 As shown, it can be seen that this structure is limited by the passband and can only work at the frequency corresponding to the bandgap transmission peak. The 100GHz dispersion curve is shown in Figure 6 As shown in FIG. 1 , the bandgap range of the surface wave photonic crystal is between 126 GHz and 278 GHz. At the same time, since it mainly works on the surface of the metal cylinder, and the metal cylinder is exposed to the external environment, it is very susceptible to interference from external factors.

[0064] See also Figure 7 to Figure 13 , provide embodiments and experimental results thereof, specifically including:

[0065] like Figure 7 to Figure 9 In this embodiment, a second metal plate is added to the above comparative example to form a novel two-dimensional closed surface wave photonic crystal structure, which is specifically composed of three layers: upper, middle and lower. The upper and lower layers are metal plates, and the middle layer is a two-dimensional periodically arranged metal column and defective metal column. The materials used in the three-layer structure are all metals commonly used in waveguides, such as silver metal. Fig. 9, the height of the metal pillar 300 is H, the height of the defective metal pillar 400 is h, the distance between two adjacent metal pillars 300 is A, the spacing between the defective pillars 400 is a (not shown), the radius of the metal pillar 300 is R, and the radius of the defective pillar 400 is r, wherein the values ​​of H, h, A, a, R, and r are all consistent with those in the comparative example.

[0066] This embodiment constructs a new type of two-dimensional closed surface wave photonic crystal structure, whose waveguide mode is as follows Fig.11 Its transmission coefficient is shown as Fig.12 As shown, the operating frequency of the waveguide mode is between 84.2 GHz and 125.3 GHz, which is obviously below the lower limit of the bandgap frequency of the two-dimensional surface wave photonic crystal in the comparative example. The near-field distribution corresponding to the 100 GHz frequency point is shown in Fig.13 As shown. This proves that: in the same surface wave photonic crystal structure, only a metal plate needs to be added on the top to cleverly move the operating frequency to the low frequency direction, and at the same time, the bandgap limitation of this photonic crystal structure can be broken, which can greatly increase the integration of the photonic crystal integrated optical path. At the same time, due to the shielding effect of the upper and lower metal plates, this structure can almost completely shield the transmission frequency corresponding to the first-order mode and the second-order mode in the dispersion curve of the photonic crystal itself, thereby allowing only the frequency corresponding to the waveguide mode introduced by the defect to pass, corresponding to Fig.12 In the transmission curve, all frequencies except the waveguide frequency are shielded, so it has strong anti-interference. In fact, since the metal in the microwave, millimeter wave and terahertz band is equivalent to a full reflection mirror, the metal plate on the top can act as a mirror to achieve the function that the current surface wave photonic crystal structure can only achieve when the size is doubled by using the mirror method.

[0067] In order to further illustrate the technical solution of the present invention, actual calculations were carried out in the 4.3 THz frequency band, wherein the dimensions corresponding to the two-dimensional closed surface wave photonic crystal structure in the 4.3 THz frequency band are H=11.64 μm, h=9.66 μm, spacing A=spacing a=11.64 μm, R=r=2.91 μm, and the photon bandgap range is 5.36 THz to 8.60 THz in the absence of a top metal plate. After the introduction of the top metal plate, the operating frequency of the waveguide structure is 3.50 THz to 5.14 THz. Obviously, after applying a metal plate on the top, the waveguide mode can be introduced outside the photon bandgap, and a mirror experiment was carried out in the 4.3 THz frequency band, which also successfully verified that the size of the surface wave photonic crystal structure can only realize the function of the two-dimensional closed surface wave photonic crystal structure with a top metal plate when it is increased by 2 times.

[0068] In summary, the two-dimensional closed surface wave photonic crystal structure of the present invention comprises a first metal plate, a second metal plate, a metal column and a defective metal column, wherein the first metal plate and the second metal plate are arranged correspondingly, the metal columns are two-dimensionally periodically arranged between the first metal plate and the second metal plate, and the opposite ends of the metal columns are respectively in contact with the first metal plate and the second metal plate to form a metal column array; the defective metal column is located in the metal column array, and the height of the defective metal column is less than the height of the surrounding metal columns. The present invention forms a surface wave photonic crystal structure through the first metal plate, the metal column and the defective metal column, and on the basis of the surface wave photonic crystal structure, by combining the second metal plate, a two-dimensional closed surface wave photonic crystal structure including the surface wave photonic crystal structure and the metal-insulator-metal structure can be integrated to provide a two-dimensional closed surface wave photonic crystal structure with strong anti-interference and high integration.

[0069] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A two-dimensional closed surface wave photonic crystal structure, characterized in that: include: A first metal plate and a second metal plate, wherein the first metal plate and the second metal plate are arranged correspondingly; Metal pillars, the metal pillars are two-dimensionally periodically arranged between the first metal plate and the second metal plate, and opposite ends of the metal pillars are respectively in contact with the first metal plate and the second metal plate to form a metal pillar array; A defective metal column, wherein the defective metal column is located in the metal column array, and the height of the defective metal column is smaller than the height of the surrounding metal columns; The morphology of the structure surrounded by the defective metal pillars includes one of a straight line, a curved shape and a T shape; The first metal plate, the second metal plate, the metal column and the defective metal column are made of the same material, wherein the material includes one of gold metal, silver metal, copper metal and aluminum metal.

2. The two-dimensional closed surface wave photonic crystal structure according to claim 1, characterized in that: The metal pillars are arranged at equal intervals.

3. The two-dimensional closed surface wave photonic crystal structure according to claim 1, characterized in that: The metal pillars have the same cross-sectional area, and the cross-sectional morphology of the metal pillars includes a circle, a square or an ellipse.

4. The two-dimensional closed surface wave photonic crystal structure according to claim 1, characterized in that: The defective metal columns are arranged at equal intervals.

5. The two-dimensional closed surface wave photonic crystal structure according to claim 1, characterized in that: The defective metal columns have the same cross-sectional area, and the cross-sectional morphology of the defective metal columns includes a circle, a square or an ellipse.

6. The two-dimensional closed surface wave photonic crystal structure according to claim 1, characterized in that: The metal column and the defective metal column have the same cross-sectional morphology.

7. The two-dimensional closed surface wave photonic crystal structure according to claim 1, characterized in that: The metal pillars and the defective metal pillars are arranged at equal intervals.

8. The two-dimensional closed surface wave photonic crystal structure according to claim 1, characterized in that: The defective metal pillars have the same height.

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