Double-split-ring heterogeneous waveguide electro-optical modulator

Abstract

The invention provides a double-split-ring heterogeneous waveguide electro-optical modulator. The device is characterized in that the device is composed of a slit waveguide 1, a graphene layer 2, a hexagonal boron nitride layer 3, a silicon dioxide substrate 4, an electrode 5, a metasurface structure 6 and a supporting silicon column 7; according to the device, a first graphene layer 2-1 is grown on a slit waveguide 1 through a chemical vapor deposition method; a hexagonal boron nitride layer 3 with a wide band gap and a low dielectric constant covers a first layer of graphene, then a second layer of graphene layer 2-2 is mechanically transferred on the hexagonal boron nitride layer, and an external voltage is applied to the first layer of graphene 2-1 through an electrode 5 to adjust the Fermi level of the second layer of graphene layer 2-2; a metasurface structure 6 formed by double opening rings is placed on the second graphene layer 2-2; and the supporting silicon column 7 is used for supporting the graphene layer 2 and the electrode 5. The waveguide is applied to a 1550nm wavelength position, the resonance intensity of a light field in the waveguide and the resonance intensity of the metasurface structure are different by changing the Fermi level of graphene, and the device achieves pi phase change under the length of 8 microns.

Description

Technical Field

[0001] The present invention relates to a dual-open-ring heterogeneous waveguide electro-optical modulation device, which can be used to construct an integrated optical fiber modulation device with high modulation efficiency and modulation rate, low modulation voltage and insertion loss at a wavelength of 1550nm, and belongs to the field of optical fiber communication and optical fiber sensing technology. Background Art

[0002] Electro-optic modulators are key devices on silicon photonic chips in modern optical communication networks. With the development of current communication networks, people have higher and higher requirements for the integration of modulators. Metasurface structure is an artificial unit periodic structure with a size smaller than the incident wavelength, which can regulate the light field at a sub-wavelength size. Metasurfaces are usually composed of metal or semiconductor microstructures. By changing the arrangement of the microstructures, effective guidance, focusing, and reflection of electromagnetic waves can be achieved.

[0003] At present, metasurface-based metawaveguides have shown the potential for multiple functions, such as applications in filters, mode coupling, etc. However, existing metawaveguide devices have the following two problems: 1. Existing heterogeneous waveguide structures are mostly fixed optical functional structures and can only be used as passive devices; 2. Most of the device application bands are in the terahertz and microwave bands, and there are few applications at a wavelength of 1550nm.

[0004] In common metasurface devices, light waves generally illuminate the metasurface vertically, so the electric field and magnetic field are parallel to the metasurface structure. The TE fundamental mode is the most commonly used transmission mode in rectangular waveguides. The electric field in this mode is parallel to the upper surface of the waveguide, while the magnetic field is perpendicular to the upper surface of the waveguide. The TM fundamental mode is the second transmission mode of rectangular waveguides. The magnetic field in this mode is parallel to the upper surface, while the electric field is perpendicular to the upper surface. Therefore, the plane wave excitation method of traditional metasurface structures is not suitable for ordinary waveguide modulators.

[0005] Since only the TE fundamental mode exists in the slot waveguide and the energy is mainly concentrated in the slot, while the magnetic field energy is mainly concentrated in the rectangular waveguides on both sides, when the energy overflows from the outlet on the upper side of the slot, it can radiate to the upper surface of the waveguide.

[0006] The present invention discloses a dual-open-ring heterogeneous waveguide electro-optical modulation device. By combining a metasurface with a waveguide, an extremely small electro-optic phase modulator operating at a wavelength of 1550nm is designed. In combination with the electro-optical properties of graphene, the metasurface structure is placed on a slit waveguide, so that the light field in the waveguide resonates with the metasurface structure, and the coupling between multiple unit structures greatly enhances the phase change. The modulation principle of the modulator is studied using an RLC circuit, and the coupling enhancement between multiple unit structures is analyzed, so that the device achieves a phase change of π at a length of 8μm. Summary of the invention

[0007] The object of the present invention is to provide an extremely small size electro-optic phase modulation device operating at a wavelength of 1550 nm, which can achieve a phase change of π at a length of 8 μm.

[0008] The object of the present invention is achieved in that:

[0009] A double-open-ring heterogeneous waveguide electro-optical modulation device in the present invention is composed of a slit waveguide 1, a graphene layer 2, a hexagonal boron nitride layer 3, a silicon dioxide substrate 4, an electrode 5, a supersurface structure 6 and a supporting silicon pillar 7; the device grows a first graphene layer 2-1 on the slit waveguide 1 by chemical vapor deposition; covers the first graphene layer with a wide band gap and a low dielectric constant hexagonal boron nitride layer 3, and then mechanically transfers a second graphene layer 2-2 on the hexagonal boron nitride layer, and adjusts the Fermi level of the first graphene layer 2-1 by applying an external voltage through the electrode 5; the double-open-ring supersurface structure 6 is placed on the second graphene layer 2-2; the supporting silicon pillar 7 is used to support the graphene layer 2 and the electrode 5.

[0010] A dual-open-ring heterogeneous waveguide electro-optical modulation device is applied at a wavelength of 1550nm. By combining the metasurface with the waveguide, an extremely small electro-optic phase modulator is realized. Combined with the electro-optical properties of the metasurface, the light field in the waveguide is caused to resonate with the metasurface structure, and the coupling between multiple unit structures greatly increases the phase change.

[0011] A double open-ring heterogeneous waveguide electro-optical modulation device chooses to cover two layers of graphene on the slit waveguide, and the space between the graphene is filled with 10nm thick hexagonal boron nitride to prevent carriers in the graphene from entering the waveguide, while forming a graphene-hexagonal boron nitride-graphene capacitor structure.

[0012] A metasurface structure of a double-open-ring heterogeneous waveguide electro-optical modulation device is composed of double open-rings, in which the period of a single ring is P and the length of a single open ring is y. m , height x m , width is w m . BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the three-dimensional structure of a double-open-ring heterogeneous waveguide electro-optical modulation device.

[0014] Figure 2 It is a transmission cross-sectional diagram of a dual-open-ring heterogeneous waveguide electro-optical modulation device.

[0015] Figure 3 It is a schematic diagram of the two-dimensional structure of the metasurface structure in a double-open-ring heterogeneous waveguide electro-optical modulation device.

[0016] Figure 4 It is a simplified principle circuit diagram of a dual open-ring heterogeneous waveguide electro-optical modulation device.

[0017] Figure 5 It is a phase diagram produced by 17 unit structures when the Fermi level of a double open-ring heterogeneous waveguide electro-optical modulation device is between 0.4eV and 1eV.

[0018] Figure 6 It is the phase change of a dual-open-ring heterogeneous waveguide electro-optical modulation device under different chemical potentials. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with specific embodiments.

[0020] Figure 1 An embodiment of a three-dimensional structure of a double-open-ring heterogeneous waveguide electro-optical modulation device is provided. The modulator is composed of a slit waveguide 1, a graphene layer 2, a hexagonal boron nitride layer 3, a silicon dioxide substrate 4, an electrode 5, a supersurface structure 6 and a supporting silicon pillar 7; the device grows a first graphene layer 2-1 on the slit waveguide 1 by chemical vapor deposition; covers the first graphene layer with a wide band gap and a low dielectric constant hexagonal boron nitride layer 3, and then mechanically transfers a second graphene layer 2-2 on the hexagonal boron nitride layer, and adjusts the Fermi level of the first graphene layer 2-1 by applying an external voltage through the electrode 5; the double-open-ring supersurface structure 6 is placed on the second graphene layer 2-2; and the supporting silicon pillar 7 is used to support the graphene layer 2 and the electrode 5.

[0021] Figure 3 A schematic diagram of the two-dimensional structure of a metasurface structure in a dual-open-ring heterogeneous waveguide electro-optical modulator is given. In common metasurface devices, light waves generally irradiate the metasurface structure vertically, so the electric field and magnetic field are parallel to the metasurface structure. The TE fundamental mode is the most commonly used transmission mode in rectangular waveguides. The electric field of this mode is parallel to the upper surface of the waveguide, while the magnetic field is perpendicular to the upper surface of the waveguide. Therefore, the plane wave excitation method of the traditional metasurface structure is not applicable to this modulator. In this modulator, since there is only the TE fundamental mode in the slit waveguide, and the energy is mainly concentrated in the slit, while the magnetic field energy is mainly used in the rectangular waveguides on both sides, when the energy overflows from the outlet of the upper slit, it radiates to the double open-ring structure above. In traditional periodic metasurface structures, there is no mutual excitation between units, while this structure has coupling between unit structures, thereby enhancing the modulation effect of the modulator.

[0022] Figure 5 This is a phase diagram of 17 unit structures when the Fermi level of a double open-ring heterogeneous waveguide electro-optical modulation device is between 0.4eV and 1eV. It can be seen that the phase mutation begins at 1460nm and ends at around 1670nm.

[0023] Figure 6 It is the phase change of a double-open-ring heterogeneous waveguide electro-optical modulation device under different chemical potentials. A single double-open buckle ring structure produces a 7.42-degree phase mutation. Because the double open rings are mutually excited, coupling between the unit structures is generated. Through simulation calculations, it is found that only 17 open ring structures are needed to achieve a phase change of π. Calculation of the phase change shows that the phase change between 1549.88nm and 1582.97nm exceeds 180 degrees. This device achieves a phase change of π at a length of 8μm.

Claims

1. A dual open-ring heterogeneous waveguide electro-optical modulation device; characterized by: It consists of a slit waveguide 1, a graphene layer 2, a hexagonal boron nitride layer 3, a silicon dioxide substrate 4, an electrode 5, a supersurface structure 6 and a supporting silicon pillar 7; the device grows a first graphene layer 2-1 on the slit waveguide 1 by chemical vapor deposition; covers the first graphene layer with a wide band gap and low dielectric constant hexagonal boron nitride layer 3, and then mechanically transfers a second graphene layer 2-2 on the hexagonal boron nitride layer, and adjusts the Fermi level of the first graphene layer 2-1 by applying an external voltage through the electrode 5; a double open ring constitutes a supersurface structure 6 placed on the second graphene layer 2-2; the supporting silicon pillar 7 is used to support the graphene layer 2 and the electrode 5.

2. According to claim 1, a dual open-ring heterogeneous waveguide electro-optical modulator is applied at a wavelength of 1550nm. By combining the metasurface with the waveguide, an extremely small electro-optic phase modulator is realized; combined with the electro-optical properties of the metasurface, the light field in the waveguide is caused to resonate with the metasurface structure, and the coupling between multiple unit structures greatly increases the phase change.

3. The metasurface structure of the double-open-ring heterogeneous waveguide electro-optical modulation device according to claim 1 is composed of double open-rings, the period of the double open-ring structure is P, and the length of a single ring is y m , height x m , width is w m .

4. According to the double open-ring heterogeneous waveguide electro-optical modulation device of claim 1, by changing the Fermi level of graphene, the device can achieve a phase change of π at a length of 8 μm.

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