A method for regulating subwavelength transmission performance of graphene-dielectric nanowire plasmon waveguide structure

Abstract

The present invention discloses a method for regulating the subwavelength transmission performance of a graphene-dielectric nanowire plasmon waveguide structure, and the obtained hybrid waveguide structure has a strong light field confinement performance. Thanks to the excellent tip focusing effect of the triangular GNW, when the vertex angle θ decreases, the graphene-light interaction area is reduced, the loss is reduced, and the mode field area of ​​the fundamental mode in the waveguide is also reduced. The graphene-dielectric nanowire hybrid waveguide structure obtained by the present invention partially breaks through the restrictive relationship between transmission loss and mode field confinement in the surface plasmon mode. The present invention not only improves the performance of the graphene plasmon waveguide, but is also compatible with silicon photonics technology, and is expected to be developed in waveguide-integrated graphene plasmon devices such as modulators, filters, resonators, etc., and can greatly reduce the size of the device.

Description

Technical Field

[0001] The present invention relates to the field of plasmon subwavelength transmission and focusing, and in particular to a method for regulating the subwavelength transmission performance of a graphene-dielectric nanowire plasmon waveguide structure. Background Art

[0002] As the research on surface plasmons continues to deepen, researchers have found that traditional precious metal plasmons have problems such as poor local characteristics of light fields in the mid- and far-infrared bands and uncontrollable performance. Therefore, it is particularly important to explore new plasmon materials. In recent years, researchers have developed a series of new plasmon materials, such as transparent conductive oxides, nitrides, graphene, molybdenum disulfide, Dirac semimetals, etc. Among the above materials, graphene can not only excite plasmon modes with strong light field localization, but also has adjustable performance. Graphene is a new type of single-atomic layer two-dimensional material, in which the valence band and conduction band in its band structure are at the Dirac point, that is, the bandgap width is zero. In the visible light band, the light absorption rate of a single layer of graphene is only 2.3%. In particular, the light absorption rate can be adjusted by changing the Fermi level. Due to the above unique electrical and optical properties, optoelectronic devices based on graphene have shown excellent application prospects and have attracted the attention of a large number of scientific researchers. Recent theoretical and experimental studies have shown that graphene can excite plasmon modes in the infrared band and has unique plasmon properties, such as strong field localization and tunability. Subsequently, research on graphene plasmons has sprung up like mushrooms after a rain, and has promoted its application in high-performance photonic devices, such as modulators, nanowaveguides, photodetectors, polarizers, couplers, optical switches, etc.

[0003] As an important component of subwavelength photonic integration, graphene plasmon nanowaveguides have attracted extensive attention. Currently, researchers have proposed a variety of hybrid plasmon waveguides based on circular nanowires (GNWs) coated with graphene layers. It is worth noting that the prior art discloses a cylindrical GNW structure based on a triangular dielectric substrate, which reduces the mode field area to ~10 -7 However, this strong light field localization is achieved at the expense of propagation distance. For example, when the frequency is 30THz and the graphene Fermi level is 0.8eV, the waveguide transmission distance is only 8μm. Although recent research has made a series of progress in this field, how to achieve a better trade-off between field confinement and transmission loss remains a challenge. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, one of the objects of the present invention is to provide a method for regulating the subwavelength transmission performance of a graphene-dielectric nanowire hybrid waveguide structure. Compared with structures of the same type, the graphene-dielectric nanowire hybrid plasmon waveguide structure of the present invention has a higher quality factor and better mode field confinement characteristics under the same parameters.

[0005] A second object of the present invention is to provide a graphene-dielectric nanowire plasmon waveguide structure obtained by the above method.

[0006] A third object of the present invention is to provide an application of the graphene-dielectric nanowire plasmon waveguide structure obtained by the above method.

[0007] One of the purposes of the present invention is achieved by the following technical solution:

[0008] A method for regulating the subwavelength transmission performance of a graphene-dielectric nanowire plasmon waveguide structure, wherein the waveguide structure comprises a triangular dielectric nanowire coated with a single layer of graphene, a circular Si nanowire, and a gap region formed by the triangular dielectric nanowire coated with a single layer of graphene and the circular Si nanowire;

[0009] Wherein, the fillet radius of the triangular dielectric nanowire coated with a single layer of graphene is r;

[0010] The triangle vertex angle of the triangular dielectric nanowire coated with a single layer of graphene is θ;

[0011] The radius of the circular Si nanowire is R;

[0012] The distance between the triangular dielectric nanowire coated with a single layer of graphene and the gap region formed by the circular Si nanowire is h. gap ;

[0013] By adjusting the fillet radius r of the triangular dielectric nanowire coated with a single layer of graphene, the triangle vertex angle θ of the triangular dielectric nanowire coated with a single layer of graphene, the radius R of the circular Si nanowire, the distance h of the gap region, gap Realize the regulation of subwavelength transmission performance of graphene-dielectric nanowire plasmon waveguide structure.

[0014] Furthermore, the triangle vertex angle θ of the triangle dielectric nanowire coated with the single-layer graphene is an acute angle.

[0015] Furthermore, the fillet radius r of the triangular dielectric nanowire coated with the single-layer graphene is 2 to 10 nm; and the radius R of the circular Si nanowire is 20 to 100 nm.

[0016] Furthermore, the triangular dielectric nanowire coated with a single layer of graphene is a triangular dielectric nanowire having a relative dielectric constant of 2 to 12 coated with a single layer of graphene; and the triangular dielectric nanowire is a Si nanowire.

[0017] Furthermore, the relative dielectric constant of the circular Si nanowire is 12.25.

[0018] Furthermore, the Fermi level of the single-layer graphene is 0.4 to 1.4 eV.

[0019] Furthermore, the filling medium of the gap region is SiO2, and the gap region distance h gap It is 1 to 20 nm.

[0020] The second object of the present invention is achieved by adopting the following technical solution:

[0021] A graphene-dielectric nanowire plasmon waveguide structure is prepared by the method.

[0022] The third object of the present invention is achieved by adopting the following technical solution:

[0023] Application of a graphene-dielectric nanowire plasmon waveguide structure, wherein the graphene-dielectric nanowire plasmon waveguide structure can be used to prepare a waveguide-integrated plasmon optical device.

[0024] Furthermore, the waveguide integrated plasmon optical device is a photonic device such as a modulator, a filter or a resonator.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention provides a method for regulating the subwave transmission performance of a graphene-dielectric nanowire hybrid waveguide structure, combining a triangular dielectric nanowire coated with a graphene layer with a circular Si nanowire, and the resulting hybrid waveguide structure has a strong light field confinement performance. The excellent tip focusing effect of the triangular GNW reduces the graphene-light interaction area as the vertex angle θ decreases, reducing the loss and also reducing the mode field area of ​​the fundamental mode in the waveguide. The graphene-dielectric nanowire hybrid waveguide structure obtained by the present invention partially breaks through the restrictive relationship between transmission loss and mode field confinement in the surface plasmon mode. In the light wave frequency range of 20 to 40 THz, the normalized mode field area of ​​the fundamental mode in the waveguide designed by the present invention is between 10 -6 At the same time, its transmission distance is 10-40 μm, and the quality factor can reach more than 2500. Compared with the same type of structure, the hybrid waveguide structure obtained by the present invention reduces the mode field area to 1 / 10 while maintaining the same propagation distance.

[0027] The present invention also provides a graphene-dielectric nanowire hybrid waveguide structure obtained by the above method and its application, using the evanescent wave around the Si waveguide to enhance the graphene-light interaction to form a waveguide-integrated graphene plasmon optical device. This measure not only improves the performance of the graphene waveguide, but is also compatible with silicon photonic technology, and is expected to be applied to waveguide-integrated plasmon optical devices, such as modulators, couplers, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of three-dimensional and two-dimensional cross-sections of a graphene-dielectric nanowire plasmon waveguide structure according to an embodiment of the present invention;

[0029] Figure 2 Graph showing the normalized electric field distribution of the fundamental mode in the graphene-dielectric nanowire plasmon waveguide structure under different parameters of the embodiment of the present invention;

[0030] Figure 3 The transmission characteristics of the plasmon mode of the graphene-dielectric nanowire plasmon waveguide structure with the gap distance h corresponding to different angles θ in the embodiment of the present invention are shown in FIG. gap The change curve of

[0031] Figure 4 The curve showing the change of the transmission characteristics of the plasmon mode in the graphene-dielectric nanowire plasmon waveguide structure according to the embodiment of the present invention with the radius R of the circular Si nanowire on the substrate at different fillet radii r;

[0032] Figure 5 The sub-wavelength transmission performance of the graphene-dielectric nanowire plasmon waveguide at different frequencies varies with the graphene Fermi level E of the embodiment of the present invention. F The change curve of

[0033] Figure 6 Different waveguide structures and fundamental mode field distribution diagrams in the structures according to the embodiments of the present invention;

[0034] Figure 7 4 is a comparison diagram of sub-wavelength transmission characteristics of different waveguide structures according to an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The present invention is further described below in conjunction with the accompanying drawings and specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0036] Example

[0037] A method for regulating the subwavelength transmission performance of a graphene-dielectric nanowire plasmon waveguide structure and a graphene-dielectric nanowire plasmon waveguide structure obtained by the method, wherein the waveguide structure comprises a triangular dielectric nanowire coated with a single layer of graphene, a circular Si nanowire, and a gap region formed by the triangular dielectric nanowire coated with a single layer of graphene and the circular Si nanowire; wherein the gap region is filled with SiO2.

[0038] The triangular dielectric nanowire coated with a single layer of graphene is a triangular dielectric nanowire with a relative dielectric constant of 2 to 12 coated with a single layer of graphene; the triangular dielectric nanowire is a Si nanowire.

[0039] The relative dielectric constant of the circular Si nanowires is 12.25.

[0040] Wherein, the fillet radius of the triangular dielectric nanowire coated with a single-layer graphene is r;

[0041] The triangle vertex angle of the triangular dielectric nanowire coated with a single-layer graphene is θ;

[0042] The radius of the circular Si nanowire is R;

[0043] The distance between the triangular dielectric nanowire coated with a single layer of graphene and the gap region formed by the circular Si nanowire is h. gap ;

[0044] By adjusting the fillet radius r of the triangular dielectric nanowire coated with a single layer of graphene, the triangle vertex angle θ of the triangular dielectric nanowire coated with a single layer of graphene, the radius R of the circular Si nanowire, the distance h of the gap region, gap Realize the regulation of subwavelength transmission performance of graphene-dielectric nanowire plasmon waveguide structure.

[0045] The following is an explanation of the control process and principle of the sub-wavelength transmission performance of the graphene-dielectric nanowire plasmon waveguide structure through examples and drawings.

[0046] Figure 1 The three-dimensional and two-dimensional cross-sectional schematic diagrams of the graphene-dielectric nanowire plasmon waveguide structure of the present invention are shown in the figure. The graphene-dielectric nanowire plasmon waveguide structure designed by the present invention is composed of a triangular dielectric nanowire coated with a single layer of graphene and a circular Si nanowire waveguide, wherein the gap area is filled with SiO2. The dielectric constant of the triangular dielectric nanowire coated with a single layer of graphene is denoted as ε1, and the dielectric constant of the circular Si is ε si The dielectric constant of SiO2 is 11.9. silicaThe height h1 of the triangular dielectric nanowire is 100 nm, and the vertex angle is θ. The vertex angle of the triangle is replaced by a rounded angle with a radius of r. At this time, the actual height h of the triangular dielectric nanowire after the vertex angle is rounded r =h1-r / sin(θ / 2)+r. The radius of the circular Si nanowire is R, and the distance between it and the triangular dielectric nanowire is h gap The optical conductivity of single-layer graphene is estimated by random phase approximation, and the calculation formula is as follows:

[0047]

[0048] Where: T is absolute temperature; k B is the Boltzmann constant; is the reduced Planck constant; e = 1.6 × 10 -19 C; ω is the angular frequency; τ=n c E F / eV F 2 is the electron relaxation time; n c is the carrier mobility in graphene; V F =10 6 m·s -1 is the Fermi speed; is the graphene Fermi level, which can be modulated by DC bias or chemical doping.

[0049] According to research, the carrier concentration n0 of graphene can reach 2.5×10 14 cm -2 , corresponding to the Fermi level E F =1.8eV. Therefore, the present invention E F The value range is 0.4 to 1.4 eV. Unless otherwise specified, in the present invention, T = 300K, E F =0.6eV,n c =10,000cm 2 V -1 s -1 In specific calculations, a single layer of graphene can be represented by a sub-nanometer thickness geometric thin layer and meshed; it can also be represented by the surface current of a nanowire, that is, J = σ g E, J are the surface current density, and E is the electric field vector.

[0050] To study the subwavelength transmission performance of graphene-dielectric nanowire plasmon waveguide, it is assumed that the plasmon mode propagates along the z direction and the electric field changes according to exp(iβz)exp(-iωt), where the propagation constant β=k0N eff , N eff By finite element method (FEM) calculation, the actual part Re (N eff)=n eff Related to dispersion, the imaginary part Im(N eff ) is related to the loss. The present invention only considers the intrinsic loss of graphene, so the propagation distance is defined as L P =1 / β”, where β”=k0Im(N eff ), k0 = 2π / λ0, λ0 is the free space wavelength. The normalized mode field area is defined as A N =A eff / A0=∫∫W(r)d 2 r / max{W(r)} / (λ0 2 / 4), where W(r) is the electromagnetic energy density, r is the position coordinate, and the quality factor Q = L P / (A eff / π) 1 / 2 .

[0051] Figure 2 The normalized electric field distribution diagram of the fundamental mode in the graphene-dielectric nanowire plasmon waveguide structure under different parameters. Figure 2 (a)~ Figure 2 (d) shows the normalized electric field distribution of the fundamental mode in the graphene-dielectric nanowire hybrid waveguide structure under different parameters, where the parameters are set to f = 30 THz, E F =0.6eV, r=5nm, R=50nm, ε1=ε silica .contrast Figure 2 (a)~ Figure 2 (d) It is found that under the same θ, h gap = 1nm, the gap energy between graphene nanowires and circular Si nanowires is more concentrated, indicating that h gap The smaller the value, the more concentrated the energy. gap When θ=π / 2, the light field diffusion range is larger, that is, the field confinement performance is poor. In summary, the light field is mainly confined in the gap area, achieving two-dimensional light field focusing.

[0052] Since the maximum field value is at the surface of the graphene layer, the following is established: Figure 1 (b) The coordinate system described. Figure 2 (e) and Figure 2 (f) It can be seen that from the x direction, h gap =1nm, the line width corresponding to θ=π / 6 is slightly smaller than that corresponding to θ=π / 2, which are about 6.8 and 7nm respectively. gap = 10nm, the line widths corresponding to θ = π / 6 and θ = π / 2 are approximately 13 and 13.5nm respectively. From the y direction, the line width of the field value curve is approximately equal to the gap distance h to a certain extent. gap , and h gap =1nm, the angle θ has little effect on the line width. gap=1nm, θ=π / 6 and θ=π / 2 correspond to line widths of about 1.3nm. gap =10nm, the angle θ has a greater influence on the line width, and the line widths corresponding to θ=π / 6 and θ=π / 2 are approximately 8 and 10nm, respectively. Therefore, the designed structure can achieve approximately 13.5×10nm 2 (or even smaller) spot, corresponding to λ0 2 / 7.4×10 5 . That is, the same h gap Under the same θ, the smaller θ is, the narrower the line width (i.e., full-height half-width) of the one-dimensional electric field value is; under the same θ, h gap The smaller it is, the narrower the line width of the one-dimensional electric field value.

[0053] Figure 3 The transmission characteristics of the plasmon mode of the graphene-dielectric nanowire plasmon waveguide structure with the gap distance h for different angles θ gap The parameters are set as f = 30 THz, E F =0.6eV, r=5nm, R=50nm, ε1=ε silica (same Figure 2 ).like Figure 3 As shown in (a), the effective mode coefficient n eff Follow h gap decreases with the increase of h. gap In the range of 1 to 10 nm, n eff The variation is large; h gap >10nm later eff Slowly decrease. Figure 3 (b) shows that as h gap The increase of propagation distance L P When θ is π / 6 and π / 3, the propagation distance L P When θ=π / 2 and 2π / 3, at h gap = L within 1~5nm P Follow h gap Increase and increase; h gap >5nm after L P Basically remain unchanged. Figure 3 (c) It can be seen that the normalized mode field area A N With h gap increases with the increase of , and the range of variation is large. When θ=2π / 3, the normalized mode field area A N The normalized mode field area is similar when θ is π / 6 and π / 3.

[0054] Figure 3 (b) Figure 3The data in (c) show that as θ decreases, the transmission distance increases while the mode field area decreases, indicating that the structure has partially broken through the constraint relationship between transmission loss and field confinement in the surface plasmon mode, that is, the mode loss is reduced while the mode field area is reduced. This is because when θ decreases, the area of ​​the graphene-light interaction region decreases, and the tip focusing effect is more significant. Figure 3 (d) It can be seen that the quality factor Q increases with h gap When θ=π / 6, the quality factor is the largest. It can be seen that the transmission characteristics of the designed waveguide structure are better when the vertex angle θ is an acute angle than when it is an obtuse angle.

[0055] Figure 4 The graph shows the variation curve of the transmission characteristics of the plasmon mode in the graphene-dielectric nanowire plasmon waveguide structure according to the substrate circular Si nanowire radius R at different fillet radii r in the embodiment of the present invention, where the parameters are f = 30 THz, E F =0.6eV, ε1 = ε silica ,θ=π / 6,h gap =2nm. Figure 4 As shown in (a), the effective mode coefficient n eff As R increases, the larger the fillet radius r of the triangular dielectric nanowire, the smaller the eff The bigger. Figure 4 (b) As can be seen, as R increases, L P The range of variation is small. P It decreases slightly within R=20-30nm and remains basically unchanged after R>40nm. Figure 4 (c) shows that as R increases, the normalized mode field area gradually decreases, and the smaller the fillet radius r, the normalized mode field area A N That is to say, in the graphene-dielectric nanowire plasmon waveguide structure of the present invention, as R increases, the loss of the graphene-dielectric nanowire hybrid waveguide structure remains basically unchanged, while the mode field area gradually decreases, once again partially breaking through the constraint relationship between the transmission loss and the mode field constraint in the surface plasmon mode, that is, achieving a substantially unchanged mode loss while reducing the mode field area. Figure 4 (d) shows that as R increases, the quality factor Q of the graphene-dielectric nanowire hybrid waveguide structure also gradually increases. When r is 2nm, the quality factor of the graphene-dielectric nanowire plasmon waveguide structure can reach more than 956. This is because the transmission loss mainly comes from the graphene layer. Since the light field is concentrated in the gap area, when R increases, the area of ​​the graphene-light interaction region remains basically unchanged, so the loss remains basically unchanged.

[0056] The present invention also studies the influence of the dielectric constant ε1 of the triangular dielectric nanowire of the graphene-dielectric nanowire plasmon waveguide structure on the transmission performance, wherein the parameters are set to f = 30 THz, E F =0.6eV, R=50nm, r=2nm, θ=π / 6, h gap =2nm. As shown in Table 1, when ε1 increases from 2 to 12, N eff Gradually increases, while the propagation distance L P Reduce, mode field area A N It also gradually increases, and the quality factor Q decreases from 1190 to 245. Therefore, dielectric materials with small dielectric constant values ​​are more helpful in improving the waveguide performance of the plasmon structure.

[0057] Table 1 Waveguide performance obtained under different dielectric constants of triangular dielectric nanowires

[0058] <![CDATA[ε1]]> <![CDATA[N eff ]]> <![CDATA[L p / μm]]> <![CDATA[A N ]]> Q 2 33.858+0.335i 4.743 <![CDATA[1.99×10 -6 ]]> 1190 2.25 34.162+0.342i 4.655 <![CDATA[2.01×10 -6 ]]> 1163 4 36.478+0.392i 4.058 <![CDATA[2.12×10 -6 ]]> 988 6 39.829+0.496i 3.206 <![CDATA[2.37×10 -6 ]]> 738 8 42.429+0.555i 2.869 <![CDATA[3.58×10 -6 ]]> 537 12 52.877+0.900i 1.769 <![CDATA[6.56×10 -6 ]]> 245

[0059] Figure 5 The graphene-dielectric nanowire plasmon waveguide subwavelength transmission performance at different frequencies varies with the graphene Fermi level E. F The change curve of the parameter is set as ε1=2,θ=π / 6,h gap =2nm, r = 2nm, R = 50nm. Figure 5 As shown in (a), with E F The increase of effective mode coefficient n eff As f0 gradually decreases and f0 increases, the effective mode coefficient n eff It also increases accordingly. Figure 5 (b) It can be seen that the propagation distance increases with the Fermi level E F The increase of E indicates that the loss decreases rapidly when the Fermi level increases. F As f0 increases, the propagation distance L P Gradually decrease. F When =1eV, the propagation distances corresponding to f=20, 30 and 40THz are 21.5μm, 14.8μm and 9.8μm respectively. Figure 5 (c) It can be seen that as the Fermi level E F Increase, normalized mode field area A N Gradually increase, f0 = 20THz and E F =1eV, the corresponding normalized mode field area is 2.11×10 -6 ; Overall A N ∈(1.19×10 -6 ~4.29×10 -6 ).from Figure 5 (d) It can be seen that as E FAs the quality factor Q increases, E F When >1eV, the Q value is as high as over 2500.

[0060] In contrast, the structure of the prior art is Wu D, Tian J, Yang R. Study of mode performances of graphene-coated nanowire integrated with triangle wedge substrate [J]. Journal of Nonlinear Optical Physics & Materials, 2018, 27 (02): 1850013. Figure 6 As shown in (a), the structure is composed of circular GNW and triangular Si nanowires, which is different from the waveguide structure of the present invention (denoted as waveguide structure A) which is composed of triangular GNW and circular Si nanowires. Figure 6 (b) shows the two waveguide structures at h gap = 2nm and h gap =10nm, the normalized electric field distribution of the fundamental mode, other parameters are ε1=2, ε silica =2.25,ε si =11.9, θ=π / 6, r=2nm, R=50nm, E F =1eV and f=30THz. Figure 6 (b) It can be clearly seen that compared with waveguide structure B, waveguide structure A has a better performance in both h gap The energy is more concentrated and the light field is better controlled. This is due to the fact that structure A uses a graphene-wrapped tip structure, and the maximum field intensity of the plasmon mode is located on the surface of the graphene layer, so the tip focusing effect is more significant. In contrast, structure B uses graphene-wrapped circular nanowires, and there is no tip effect. Although the triangular Si nanowires in structure B are tip structures, the maximum field intensity is located on the surface of the graphene layer, and the tip focusing effect is weaker than that of structure A.

[0061] The present invention further compares the sub-wavelength transmission characteristics of waveguide structures A and B. Figure 7 As shown, the four dotted data points correspond to f = 20, 22, 24, ... 40 THz from right to left, and the other parameters are the same Figure 6 (b) Two different waveguide structure gap distances h gap The values ​​are 2nm and 10nm. gap =10nm, the fundamental mode propagation distance L in waveguide structures A and B P The normalized mode field area of ​​the fundamental mode of waveguide structure A (6.54×10 -6~1.58×10 -5 ) than structure B (4.98×10 -5 ~1.1×10 -4 )) is one order of magnitude smaller. gap = 2nm, the fundamental mode propagation distance L in waveguide structures A and B P The normalized mode field area of ​​the fundamental mode of waveguide structure A (2.11×10 -6 ~3.33×10 -6 ) than the B structure (1.93×10 -5 ~2.57×10 -5 ) is one order of magnitude smaller. It can be seen that in the range of 20 to 40 THz, the transmission losses of the two waveguide structures are basically the same, but the optical field confinement performance of waveguide structure A is better than that of waveguide structure B, that is, a better trade-off is achieved between field confinement and transmission loss.

[0062] In summary, the present invention provides a method for regulating the sub-wave transmission performance of a graphene-dielectric nanowire plasmon waveguide structure, and the resulting plasmon waveguide structure has a strong light field confinement performance. The excellent tip focusing effect of the triangular GNW reduces the graphene-light interaction area with the decrease of the vertex angle θ, thereby reducing the loss, further reducing the waveguide wear loss and the mode field area. The graphene-dielectric nanowire plasmon waveguide structure obtained by the present invention partially breaks through the restrictive relationship between transmission loss and mode field confinement in the surface plasmon mode. Within 20 to 40 THz, the normalized mode field area of ​​the fundamental mode in the waveguide designed by the present invention is between ~10 -6 At the same time, its transmission distance is between 10 and 40 μm, and its quality factor can reach more than 2500. Compared with the same type of structure, the plasmon waveguide structure obtained by the present invention reduces the mode field area to 1 / 10 while maintaining the same propagation distance. The present invention not only improves the performance of graphene waveguides, but is also compatible with silicon photonics technology. It is expected to be developed for applications in waveguide-integrated graphene plasmon devices such as modulators, filters, resonators, etc., and can significantly reduce the size of the device.

[0063] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A method for regulating the subwavelength transmission performance of a graphene-dielectric nanowire plasmon waveguide structure, characterized in that: The waveguide structure includes a triangular dielectric nanowire coated with a single layer of graphene, a circular Si nanowire, and a gap region formed by the triangular dielectric nanowire coated with a single layer of graphene and the circular Si nanowire; Wherein, the fillet radius of the triangular dielectric nanowire coated with a single layer of graphene is r; The triangle vertex angle of the triangular dielectric nanowire coated with a single layer of graphene is θ; The radius of the circular Si nanowire is R; The distance between the triangular dielectric nanowire coated with a single layer of graphene and the gap region formed by the circular Si nanowire is h. gap ; By adjusting the fillet radius r of the triangular dielectric nanowire coated with a single layer of graphene, the triangle vertex angle θ of the triangular dielectric nanowire coated with a single layer of graphene, the radius R of the circular Si nanowire, the distance h of the gap region, gap Realize the regulation of sub-wavelength transmission performance of graphene-dielectric nanowire plasmon waveguide structure; The frequency of light waves regulated by the graphene-dielectric nanowire plasmon waveguide structure is between 20 and 40 THz.

2. The method for regulating the sub-wavelength transmission performance of a graphene-dielectric nanowire plasmon waveguide structure according to claim 1, characterized in that: The triangle vertex angle θ of the triangle dielectric nanowire coated with the single-layer graphene is an acute angle.

3. The method for regulating the sub-wavelength transmission performance of a graphene-dielectric nanowire plasmon waveguide structure according to claim 1, characterized in that: The fillet radius r of the triangular dielectric nanowire coated with a single layer of graphene is 2-10 nm; the radius R of the circular Si nanowire is 20-100 nm.

4. The method for regulating the sub-wavelength transmission performance of a graphene-dielectric nanowire plasmon waveguide structure according to claim 1, characterized in that: The triangular dielectric nanowire coated with a single layer of graphene is a triangular dielectric nanowire with a relative dielectric constant of 2 to 12 coated with a single layer of graphene; the triangular dielectric nanowire is a Si nanowire.

5. The method for regulating the sub-wavelength transmission performance of a graphene-dielectric nanowire plasmon waveguide structure according to claim 4, characterized in that: The relative dielectric constant of the circular Si nanowire is 12.

25.

6. The method for regulating the sub-wavelength transmission performance of a graphene-dielectric nanowire plasmon waveguide structure according to claim 1, characterized in that: The Fermi level of the single-layer graphene is 0.4-1.4 eV.

7. The method for regulating the sub-wavelength transmission performance of a graphene-dielectric nanowire plasmon waveguide structure according to claim 1, characterized in that: The filling medium of the gap region is SiO2, and the distance between the gap region and gap 1~20 nm.

8. A graphene-dielectric nanowire plasmon waveguide structure, characterized in that: Prepared by the method according to any one of claims 1 to 7.

9. The use of the graphene-dielectric nanowire plasmon waveguide structure according to claim 8, characterized in that: The graphene-dielectric nanowire plasmon waveguide structure can be used to prepare a waveguide-integrated plasmon optical device. The frequency of light waves regulated by the graphene-dielectric nanowire plasmon waveguide structure is between 20 and 40 THz.

10. The use of the graphene-dielectric nanowire plasmon waveguide structure according to claim 9, characterized in that: The waveguide integrated plasmon optical device is a modulator, a filter or a resonator.

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