Dynamically tunable multi-band terahertz transmission modulator based on graphene metasurface

Abstract

This invention belongs to the field of wireless communication and relates to terahertz modulators in terahertz communication systems. Specifically, it provides a dynamically tunable multi-band terahertz transmissive modulator based on a graphene metasurface to solve the problems of existing technologies, such as single operating frequency band, low spectrum utilization, poor modulation capability, and insufficient modulation depth. The terahertz transmissive modulator in this invention consists of several modulation units arranged in a periodic array. Each modulation unit is composed of a substrate layer and a graphene metasurface layer disposed on its upper surface. The graphene metasurface layer adopts an axisymmetric structure, consisting of a double-hole ring, a long rectangular stub, and two short rectangular stubs. In summary, this invention obtains a terahertz transmissive modulator through the structural design of the graphene metasurface layer and the substrate layer, achieving dynamically tunable multi-band modulation within the terahertz frequency range, and possessing excellent characteristics such as simple structure, wide operating range, large modulation depth, and high sensitivity.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication and relates to terahertz modulators in terahertz communication systems. Specifically, it provides a multi-band terahertz transmission modulator based on a dynamically tunable graphene metasurface. Background Technology

[0002] Terahertz waves are electromagnetic waves with frequencies between 100 GHz and 10 THz and wavelengths between 0.03 mm and 3 mm, combining the advantages of long-wavelength submillimeter waves and short-wavelength infrared waves. Due to their superior transmission capabilities, terahertz waves are expected to become an important communication frequency band after microwave and optical communication, playing a crucial role in military equipment, national security, and civilian communications. Utilizing terahertz waves for communication is an effective solution to alleviate the increasingly strained spectrum resources and wireless system capacity limitations. Among these, terahertz modulators, as one of the most core key devices in terahertz communication systems, have become a hot topic in terahertz science and technology research.

[0003] Metamaterials are synthetic materials composed of periodically arranged subwavelength units that exhibit extraordinary electromagnetic properties not found in natural materials. These unique properties include artificial magnetization, negative refractive index, and electromagnetically induced transparency. Therefore, researchers have proposed a variety of metamaterials that can be configured for tunable design, ranging from two-dimensional (2D) to three-dimensional (3D) structures. For example, in patent document CN117950211A, Rongbin She et al. disclosed a terahertz modulator with an all-dielectric metasurface composite structure, its preparation method, and its application, achieving single-peak transmission modulation in the terahertz band. Similarly, in patent document CN118625545A, Jing Zhang et al. disclosed a lattice-enhanced multifunctional terahertz optical control modulator, achieving double-peak modulation in the terahertz band by changing the lattice period. Furthermore, in patent document CN119511564A, Fangzhou Shu et al. disclosed a terahertz modulator based on an aluminum and germanium-antimony-tellurium composite dumbbell-shaped aperture array, utilizing the germanium-antimony-tellurium phase transition to achieve single-peak transmittance adjustment in the terahertz band. However, traditional metamaterial modulators cannot be actively adjusted; once their structure is manufactured, their electromagnetic properties cannot be changed, making it difficult for them to meet the requirements of complex and variable electromagnetic environments.

[0004] It is worth noting that graphene, as a two-dimensional honeycomb lattice structure composed of tightly packed carbon atoms, exhibits excellent tunable conductivity and carrier mobility, reaching 15,000 cm⁻¹ at room temperature. 2 / (Vs); Simultaneously, the surface conductivity of graphene can be easily adjusted by an external voltage without altering structural parameters. Compared to noble metals, graphene offers more advantages in surface plasmons research; for example, by designing graphene patterned structures, surface plasmon polaritons (SPPs) in a transverse magnetic mode can be generated on the graphene surface under external light field excitation. This is a phenomenon of collective oscillation of free electrons on the surface. Incident electromagnetic waves of a specific frequency will be confined to the patterned region of the surface, thereby achieving an actively tunable plasma-induced transparency (PIT) effect. This enables a range of applications, including electro-optic modulators and optical switching devices. Furthermore, another key application based on the PIT effect generated by graphene metasurfaces is sensing, as the resonance peak frequency within the PIT window is highly sensitive to changes in the refractive index of the surrounding medium. For metallic metasurfaces, the PIT effect can be achieved to some extent through specific nanostructure design. However, due to inherent challenges such as high loss, limited frequency tunability, weak plasmon intensity, and inefficient coupling, achieving actively controllable terahertz modulation remains difficult. Therefore, researching terahertz modulators based on graphene metasurfaces is of practical significance. Summary of the Invention

[0005] The purpose of this invention is to provide a dynamically tunable multi-band terahertz transmissive modulator based on graphene metasurfaces, to solve the problems of existing terahertz modulators, such as single operating frequency band, low spectral utilization, poor modulation capability, and insufficient modulation depth. This invention creatively proposes a dynamically tunable multi-band terahertz transmissive modulator based on graphene metasurfaces, achieving dynamically tunable multi-operating frequency band modulation within the terahertz frequency range, and possessing excellent characteristics such as simple structure, wide operating range, large modulation depth, and high sensitivity.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A dynamically tunable multi-band terahertz transmissive modulator based on graphene metasurface is disclosed, comprising several modulation units arranged in a periodic array. Each modulation unit consists of a substrate and a graphene metasurface layer disposed on its upper surface. The graphene metasurface layer is characterized by an axisymmetric structure, consisting of a double-ended ring, a long rectangular branch, and two short rectangular branches. The center of the double-ended ring coincides with the center of the upper surface of the substrate, and the opening direction forms an angle θ with the midline of the upper surface of the substrate. The long rectangular branch is disposed along the opening of the double-ended ring, and the two midlines of the long rectangular branch coincide with the two axes of symmetry of the graphene metasurface layer. The two short rectangular branches are disposed within the double-ended ring and are perpendicular to the long rectangular branch.

[0008] Furthermore, the included angle θ = 15° to 45°.

[0009] Furthermore, the modulation unit adopts a square structure with a unit period P = 102 μm to 106 μm.

[0010] Furthermore, the substrate layer is made of silicon or silicon dioxide, with a thickness H of 100 μm to 150 μm.

[0011] Furthermore, the thickness of the graphene metasurface layer is 0.334 nm.

[0012] Furthermore, the outer diameter of the double-ended annulus is R2 = 48μm~52μm, the inner diameter is R1 = 35μm~45μm, and the opening width is W3 = 5μm~15μm.

[0013] Furthermore, the length of the long rectangular branch is L2 = 95μm to 105μm, and the width is W2 = 0.5μm to 0.6μm; the length of the short rectangular branch is L1 = 25μm to 35μm, and the width is W1 = 0.5μm to 0.6μm; the distance between the two short rectangular branches is a = 10μm to 30μm.

[0014] Based on the above technical solution, the beneficial effect of the present invention is that it provides a multi-band terahertz transmission modulator based on a dynamically tunable graphene metasurface, which has the characteristics of simple structure, multiple bands, dynamic tunability, high resonance intensity, and high sensing sensitivity; the specific advantages are as follows:

[0015] (1) Compared with the prior art, the present invention achieves excellent characteristics such as multiple resonant frequency bands, high resonant intensity and large modulation range, and its minimum full width at half maximum (FWHM) is only 6.3 GHz;

[0016] (2) The device unit proposed in this invention has a simple structure, excellent performance, and excellent resonant frequency band and dynamic modulated transmission performance, which greatly increases the application range of terahertz modulators.

[0017] (3) The present invention has good polarization switching performance. By changing the polarization angle, the terahertz transmission efficiency can be modulated, and it has switchable multiple resonant frequency bands.

[0018] (4) This invention has excellent sensing performance. As the refractive index n of the environment increases, the resonant frequency band gradually shifts to lower frequencies, while the transmission efficiency remains almost unchanged. The highest sensitivity S and the quality factor FOM reach 510 GHz / RIU and 46.43 RIU, respectively. -1 . Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the dynamically tunable multi-band terahertz transmission modulator based on graphene metasurface in this invention.

[0020] Figure 2This is a schematic diagram of the unit structure of the dynamically tunable multi-band terahertz transmission modulator based on graphene metasurface in this invention.

[0021] Figure 3 This is a transmission efficiency curve of the dynamically tunable multi-band terahertz transmission modulator based on graphene metasurface in the present invention in TE mode (φ=0°).

[0022] Figure 4 The transmission efficiency of the dynamically tunable multi-band terahertz transmission modulator based on graphene metasurface in this invention varies with the chemical potential V of the graphene metasurface in the range of 100–800 GHz. f The curve showing the change from 0.4 eV to 0.8 eV.

[0023] Figure 5 This is a graph showing the transmission efficiency of the dynamically tunable multi-band terahertz transmissive modulator based on graphene metasurface in the 100–800 GHz range as a function of the relaxation time τ of the graphene metasurface (increasing from 0.2 Ps to 0.8 Ps).

[0024] Figure 6 The transmission efficiency of the dynamically tunable multi-band terahertz transmission modulator based on graphene metasurface in this invention varies with the incident polarization angle in the range of 100–800 GHz. (The curve showing the change from 0° to 90°).

[0025] Figure 7 This is a graph showing the transmission efficiency of the dynamically tunable multi-band terahertz transmission modulator based on graphene metasurface in the present invention as a function of substrate thickness H (from 100 μm to 150 μm) in the range of 100–800 GHz.

[0026] Figure 8 This is a graph showing the transmission efficiency of the dynamically tunable multi-band terahertz transmission modulator based on graphene metasurface in the 100–800 GHz range as a function of the ambient refractive index n (from 1.00 to 1.04). Detailed Implementation

[0027] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0028] This embodiment provides a dynamically tunable multi-band terahertz transmission modulator based on a graphene metasurface, such as... Figure 1As shown, the system consists of several modulation units arranged in a periodic array, with any two adjacent modulation units joined without gaps. Each modulation unit comprises a substrate layer 2 and a graphene metasurface layer 1 disposed on its upper surface. The modulation units adopt a square structure with a unit period P = 102 μm to 106 μm. The substrate layer 2 is made of silicon or silicon dioxide, with a refractive index ε = 1.53 to 1.96 and a thickness H = 100 μm to 150 μm. The thickness of the graphene metasurface layer 1 is 0.334 nm. The intrinsic graphene has a zero band gap, making it metallic, and its conductivity can be expressed as σ. g =σ intra +σ inter , where σ intra and σ inter These represent the in-band conductance and inter-band conductance, respectively, and can be expressed by the following formula:

[0029]

[0030] Where j represents the imaginary number (j×j=-1), e=1.6×10 -19 C represents the charge of an electron, K B =1.38×10 -23 J / K represents the Boltzmann constant, h = 1.05 × 10⁻⁶ -34 J·s represents the reduced Planck constant, T = 300K represents the ambient temperature, w = 2πf represents the angular frequency of the incident electromagnetic wave (f = 100–800 GHz is the incident electromagnetic wave frequency), and V f τ and τ represent the chemical potential and relaxation time of graphene, respectively;

[0031] Under room temperature conditions (hω<<2|V) f |), the interband conductivity σ of graphene inter This can be ignored; therefore, the surface conductivity mainly depends on the in-band contribution; according to the Pauli exclusion principle, the conductivity of graphene can be simplified to the Drude model:

[0032]

[0033] According to equation (3), the electrical conductivity of the graphene metasurface can be increased by changing the chemical potential V. f The relaxation time τ can be dynamically adjusted without changing its geometry; correspondingly, the dielectric constant ε of the graphene metamaterial... g (ω) can be calculated from the conductivity σ(ω):

[0034]

[0035] Where Δ = 0.334 nm represents the thickness of the graphene metasurface, and ε0 = 8.85 × 10⁻⁶.-12 F / m represents the vacuum dielectric constant;

[0036] Therefore, it can be seen that by controlling the chemical potential V of graphene metamaterials... f By dynamically adjusting the dielectric constant using the relaxation time τ, a dielectric constant model of graphene metamaterials can be established to simulate and analyze its dynamic modulation properties in terahertz modulation devices. Based on this, this invention uses Matlab software to calculate different chemical potentials V. f The graphene material with relaxation time τ was imported into the finite-time difference software (FDTD Solutions) for the construction and simulation analysis of a terahertz transmission modulator, and its chemical potential V was determined. f The modulation range is 0.40eV to 0.80eV, and the modulation range of relaxation time τ is 0.20Ps to 0.80Ps.

[0037] Graphene metasurface layers such as Figure 2 As shown, its patterned structure can be realized using picosecond laser processing or photolithography; the unit patterned structure of the graphene metasurface layer, such as Figure 2 As shown, the graphene metasurface layer adopts an axisymmetric structure, consisting of a double-ended ring, a long rectangular branch, and two short rectangular branches. The center of the double-ended ring coincides with the center of the upper surface of the substrate layer, and the opening direction forms an angle θ with the midline of the upper surface of the substrate layer. The long rectangular branch is positioned along the opening of the double-ended ring, and the two midlines of the long rectangular branch coincide with the two axes of symmetry of the graphene metasurface layer. The two short rectangular branches are positioned inside the double-ended ring and are perpendicular to the long rectangular branch. It should also be noted that the double-ended ring is formed by opening the ring along any diameter, and the edge of the opening is parallel to that diameter; the direction of that diameter is defined as the opening direction of the double-ended ring. Furthermore, the geometric dimensions of the graphene metasurface layer are set as follows: R1 = 35–45 μm, R2 = 48–52 μm, W1 = W2 = 0.5 μm, W3 = 5–15 μm, L1 = 25–35 μm, L2 = 95–105 μm, a = 10–30 μm, and θ = 15°–45°.

[0038] The beneficial effects of the present invention will be explained in detail below with reference to simulation tests.

[0039] During the simulation test, the incident electromagnetic wave range was set to 100GHz to 800GHz, and the incident light wave propagated perpendicularly to the XOY plane and incident downwards; when the electric field (E) propagated along the X and Y axes, the polarization angle was... 0° and 90° represent the transverse electric (TE) mode and transverse magnetic (TM) mode, respectively. The transmission characteristics of the terahertz modulator were simulated using Lumerical Finite Difference Time Domain (FDTD) software. During the simulation, the mesh size was 2nm×2nm×2nm to ensure the reliability of the model. Periodic boundary conditions were selected in the X and Y directions, and a perfectly matched layer (PML) boundary condition was added in the Z-axis direction.

[0040] like Figure 3 The figure shows the transmission efficiency curve of the above-mentioned dynamically tunable multi-band terahertz transmission modulator based on graphene metasurface in TE mode (φ=0°). As can be seen from the figure, in TE mode... When the incident electromagnetic wave frequency is 100–800 GHz, the terahertz transmission modulator generates four resonance peaks, located at 293.9 GHz (ω1), 318.4 GHz (ω2), 557.8 GHz (ω3), and 664.9 GHz (ω4), respectively. The corresponding full width at half maximum (FWHM) values ​​are 29.4 GHz, 25.2 GHz, 6.3 GHz, and 12.6 GHz, respectively. The terahertz transmission efficiencies at the four resonance frequencies are 7.2%, 5.5%, 5.7%, and 2.4%, respectively. Meanwhile, the maximum transmission efficiency in the non-resonant frequency band can reach 98.5%.

[0041] like Figure 4 The figure shows the transmission efficiency of the aforementioned dynamically tunable multi-band terahertz transmission modulator based on graphene metasurface as a function of the chemical potential V of the graphene metasurface in the range of 100–800 GHz. f The curve showing the change from 0.4 eV to 0.8 eV is obtained by applying an external gate voltage V. g It can effectively regulate the chemical potential V of graphene metasurfaces. f The formula is as follows:

[0042]

[0043] Where V is the Fermi velocity (V0) F =c / 300, c = 3 × 10 8 m / s represents the speed of light in a vacuum, V g The applied gate voltage is ε0 = 8.85 × 10⁻⁶. 12 F / m represents the vacuum permittivity, ε g The relative permittivity of graphene metamaterial is represented by e = 1.6 × 10⁻⁶. -19 C represents the charge of the electron, and H represents the thickness of the base layer;

[0044] Based on the dynamic tunability of graphene's chemical potential, by Figure 5It is evident that as the graphene chemical potential increases from 0.4 eV to 0.8 eV, the resonant intensity of the terahertz transmission modulator changes only slightly, and all four resonant frequencies shift towards higher frequencies. The modulation ranges of the four resonant frequencies are 284.8–303.2 GHz, 309.3–328.2 GHz, 548.7–572.5 GHz, and 649.5–688.4 GHz, respectively. Furthermore, the modulation trend of the resonant frequencies exhibits a certain linear relationship with the graphene chemical potential. This means that by adjusting the graphene chemical potential, multiple resonant frequencies of the terahertz transmission modulator can be dynamically controlled within the range of 100–800 GHz, thereby improving the spectral efficiency of the terahertz modulation device and enhancing its practical application performance.

[0045] like Figure 5 The figure shows the transmission efficiency of the aforementioned dynamically tunable multi-band terahertz transmission modulator based on graphene metasurface in the range of 100–800 GHz as a function of the graphene metasurface relaxation time τ (increasing from 0.2 Ps to 0.8 Ps). The electronic relaxation time τ of graphene can be adjusted using the following formula:

[0046]

[0047] Among them, V f v and e represent the chemical potential and carrier mobility of graphene, respectively, and e = 1.6 × 10⁻⁶. -19 C represents the charge of the electron, v F =10 6 m / s represents the Fermi velocity; in practical applications, by adding or subtracting organic molecules from the surface of the graphene metasurface layer, the carrier mobility v can be significantly changed, thereby changing the relaxation time τ.

[0048] Based on the dynamic tunability of relaxation time, by Figure 5As can be seen, with the increase of relaxation time τ, the transmission efficiency at the four resonant frequencies can be effectively modulated while the resonant frequencies remain unchanged. The modulation ranges of the terahertz transmission efficiency at the four resonant frequencies are 7.2%–75.3%, 5.5%–77.2%, 5.7%–53.8%, and 2.4%–60.1%, respectively, with modulation depths corresponding to 68.1%, 71.7%, 48.1%, and 57.7%. This unique modulation characteristic originates from the change in the graphene carrier scattering mechanism. The change in relaxation time τ effectively reduces the electron-phonon scattering probability and increases the real part of the graphene surface conductivity, thereby significantly enhancing the local field confinement capability. Therefore, compared with the traditional noble metal metasurface-dependent geometry-reconstruction-based modulation method, the designed dynamically tunable multi-band terahertz transmission modulator based on graphene metasurfaces can effectively modulate the transmission spectrum by modulating the chemical potential and relaxation time of the graphene layer without changing the geometry, and can be widely used in the fields of controllable optical switches and detection.

[0049] like Figure 6 The figure shows the transmission efficiency of the aforementioned dynamically tunable multi-band terahertz transmission modulator based on graphene metasurface as a function of incident polarization angle in the range of 100–800 GHz. The curve showing the change (from 0° to 90°) illustrates the polarization-dependent characteristics of the proposed terahertz modulator, which, due to its asymmetric structure, exhibits polarization-dependent properties. Based on this, a comparison is made with polarization... and The transmission curve in the mode is determined by Figure 6 It can be seen that the resonant position at ω1 remains essentially unchanged; conversely, the resonant positions at ω2, ω3, and ω4 shift towards higher frequencies, with modulation ranges of 318.4–345.2 GHz, 557.8–583.3 GHz, and 664.9–717.4 GHz, respectively. Simultaneously, in TM mode, the resonant intensity of the terahertz modulator at ω1 and ω2 decreases; the modulation ranges of transmission efficiency are 7.2%–41.9% and 5.5%–32.7%, respectively, with modulation depths corresponding to 34.7% and 27.2%. It is noteworthy that when the polarization angle of the incident polarized light… At this time, the terahertz modulator generates three resonance peaks. The resonance frequencies at ω1 and ω2 merge to 305.2 GHz, while the resonance intensity remains essentially unchanged. Simultaneously, the resonance intensity at ω3 and ω4 decreases, with modulation ranges of transmission efficiency of 5.7%–49.8% and 2.4%–45.3%, respectively, and modulation depths corresponding to 44.1% and 42.9%. Therefore, modulation of the terahertz transmission device can be achieved by changing the polarization angle of the incident electromagnetic wave. It exhibits good polarization-switching performance and displays switchable multi-resonance and polarization-dependent characteristics, making it suitable for optical logic applications.

[0050] like Figure 7 The figure shows the transmission efficiency of the aforementioned dynamically tunable multi-band terahertz transmission modulator based on graphene metasurface as a function of substrate thickness H (from 100 μm to 150 μm) in the range of 100–800 GHz. As can be seen from the figure, with the increase of substrate thickness H, all resonant frequencies of the terahertz transmission modulator shift to lower frequencies; in particular, the modulation range of the resonant frequency at ω4 can decrease from 676.2 GHz to 655.1 GHz, while the resonant intensity remains essentially unchanged. This is due to the path phase of the terahertz wave propagating in the substrate. This can be expressed as the following formula:

[0051]

[0052] Where H and ε are the thickness and dielectric constant of the substrate, respectively, and f is the frequency of the interfering electromagnetic wave; when the electromagnetic wave is incident perpendicularly, the path phase... Since the incident angle θ can be considered a fixed value, when the thickness H of the substrate layer increases, the frequency f of the interference electromagnetic wave will decrease, which will cause the resonant frequency of the device to shift to a lower frequency. It can be seen that the multi-band terahertz transmission modulator based on the dynamic tunable graphene metasurface proposed in this invention has excellent operating frequency modulation characteristics.

[0053] like Figure 8 The figure shows the transmission efficiency of the aforementioned dynamically tunable multi-band terahertz transmissive modulator based on graphene metasurface as a function of the ambient refractive index n (from 1.00 to 1.04) in the 100–800 GHz range. The sensing characteristics of the terahertz transmissive modulator in the sensing field were investigated. By covering different analytes onto the graphene metasurface layer, the refractive index parameter of the surrounding environment changes, thereby altering the transmission characteristics of the modulator. Therefore, by monitoring the shift in the resonant frequency of this terahertz transmissive modulator, the refractive index of the analyte can be sensed and detected. Figure 8It is evident that as the refractive index n of the environment increases, the four resonant frequencies gradually shift to lower frequencies, while the transmission efficiency remains almost constant. The modulation ranges of the four resonant frequencies are 286.9–293.9 GHz, 312.8–318.4 GHz, 546.1–557.8 GHz, and 644.5–664.9 GHz, respectively. Furthermore, based on the formula for calculating sensitivity S: S = Δf / Δn, where Δf and Δn represent the changes in resonant frequency and environmental refractive index, the sensitivities of the terahertz transmission modulator at the four operating frequencies are calculated to be 175 GHz / RIU, 140 GHz / RIU, 292.5 GHz / RIU, and 510 GHz / RIU, respectively. Additionally, based on the formula for calculating the quality factor FOM: FOM = S / FWHM, where FWHM is the full width at half maximum (FWHM) at the resonant frequency, the calculated FOM at the four resonant frequencies reaches 5.95 RIU. -1 5.56RIU -1 46.43RIU -1 and 40.48RIU -1 The results show that the above-mentioned terahertz transmission modulator has excellent sensing sensitivity and detection accuracy, and can be widely used in the field of terahertz sensing and detection.

[0054] In summary, this invention, based on the structural design of a graphene metasurface layer and a substrate layer, yields a terahertz transmission modulator that generates four resonance peaks in the 100–800 GHz range, located at 293.9 GHz (ω1), 318.4 GHz (ω2), 557.8 GHz (ω3), and 664.9 GHz (ω4), with a minimum full width at half maximum (FWHM) of only 6.3 GHz. Firstly, by altering the chemical potential and relaxation time of the graphene metasurface, dynamic control of the resonant frequency band and transmission efficiency of the terahertz transmission modulator is achieved, with the maximum transmission efficiency modulation depth reaching [value missing]. The invention achieves the following: First, the resonant frequency of the terahertz transmission modulator can be adjusted by changing the thickness of the substrate layer; second, the invention modulates the terahertz transmission device by changing the polarization angle of the incident electromagnetic wave, exhibiting good polarization switching performance and switchable multi-resonance and polarization-dependent characteristics; third, the invention studies the sensing characteristics of the terahertz transmission modulator by changing the environmental refractive index, calculating that the highest sensitivity S in the four resonant frequency bands reaches 510 GHz / RIU, and the maximum quality factor FOM reaches 46.43 RIU. -1 .

[0055] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

Claims

1. A graphene super-surface based dynamic tunable multi-band terahertz transmission modulator, comprising a plurality of modulation units arranged in a periodic array, each modulation unit comprising a substrate layer and a graphene super-surface layer disposed on the top surface of the substrate layer; characterized in that, The modulation unit adopts a square structure, and the graphene super surface layer adopts an axisymmetric structure and is composed of a double-port circular ring, a long rectangular branch and two short rectangular branches θ The center of the double-port circular ring is coincided with the center of the upper surface of the base layer, and the opening direction of the double-port circular ring forms an angle with the center line of the upper surface of the base layer The long rectangular branch is arranged along the opening of the double-port circular ring, and the two center lines of the long rectangular branch are coincided with the two symmetry axes of the graphene super surface layer The two short rectangular branches are arranged in the double-port circular ring and are perpendicular to the long rectangular branch 2. The graphene super-surface based dynamically tunable multi-band terahertz transmission modulator according to claim 1, wherein, included angle θ = 15°~45°.

3. The graphene super-surface based dynamically tunable multi-band terahertz transmission modulator according to claim 1, wherein, Cell cycle of the modulation unit P = 102 μm ~ 106 μm.

4. The graphene super-surface based dynamically tunable multi-band terahertz transmission modulator of claim 1, wherein, The substrate layer is made of silicon or silicon dioxide, with a thickness of H =100μm ~150 μm.

5. The graphene super-surface based dynamically tunable multi-band terahertz transmission modulator according to claim 1, wherein, The thickness of the graphene super-surface layer is 0.334 nm.

6. The graphene super-surface based dynamically tunable multi-band terahertz transmission modulator according to claim 1, wherein, Outer diameter of the double- mouthed circular ring R 2 = 48 μm ~ 52 μm, inner diameter R 1 = 35 μm ~ 45 μm, opening width W 3 = 5 μm ~ 15 μm.

7. The graphene super-surface based dynamically tunable multi-band terahertz transmission modulator according to claim 1, wherein, Length of the long rectangular branch L 2 = 95 μm ~ 105 μm, width W 2 = 0.5 μm ~ 0.6 μm; length of the short rectangular branch L 1 = 25 μm ~ 35 μm, width W 1 = 0.5 μm ~ 0.6 μm, spacing between the two short rectangular branches a = 10 μm ~ 30 μm.

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