Electro-optical modulator based on silicon-based heterogeneous integrated film lithium niobate platform

Abstract

The invention relates to an electro-optical modulator based on a silicon-based heterogeneous integrated film lithium niobate platform. The electro-optical modulator comprises a first silicon-based multimode interference coupler, a first silicon-lithium niobate interlayer coupler, a T-shaped microstructure electrode, a lithium niobate modulation arm, a second silicon-lithium niobate interlayer coupler and a second silicon-based multimode interference coupler which are connected in sequence, the silicon-lithium niobate interlayer coupler comprises a lithium niobate ridge waveguide, a silicon dioxide buffer layer, a silicon waveguide and a substrate from top to bottom. The T-shaped micro-structure electrode lithium niobate electro-optical modulator has the advantages of a T-shaped micro-structure electrode lithium niobate electro-optical modulator and the advantages of a silicon-based heterogeneous integrated lithium niobate platform, the advantages of high electro-optical bandwidth and low power consumption of the T-shaped micro-structure electrode lithium niobate electro-optical modulator are kept, and the T-shaped micro-structure electrode lithium niobate electro-optical modulator has wafer-level preparation and large-scale integration capacity based on mature silicon-based optoelectronic devices.

Description

Technical Field

[0001] The invention belongs to the field of electro-optic modulators, and in particular relates to an electro-optic modulator based on a silicon-based heterogeneous integrated thin film lithium niobate platform. Background Art

[0002] With the rapid development of technologies such as language large models, autonomous driving, and cloud computing, the demand for high-speed data transmission is growing. Traditional electrical interconnection has been unable to meet the transmission capacity and transmission rate requirements of large-scale server systems such as high-performance computing clusters and data centers. Optical interconnection has the advantages of high transmission rate, large communication capacity, low power consumption, and low crosstalk. In order to meet the transmission needs of massive data, optical interconnection has been widely used in data interconnection of large-scale server systems such as high-performance computing clusters and data centers. At present, the T-type microstructure electrode lithium niobate electro-optical modulator is the electro-optical modulator with the highest transmission rate reported.

[0003] Traditional T-shaped microstructure electrode lithium niobate electro-optic modulators need to match the microwave refractive index with the light group refractive index to improve the bandwidth. The current mainstream solutions are: 1. Use a quartz substrate; 2. Wet-etch and hollow out the silicon substrate after bonding. The quartz substrate T-shaped microstructure electrode modulator is incompatible with the existing mature commercial silicon substrate platform, has high cost, and cannot be integrated on a large scale with mature silicon-based optoelectronic devices. The silicon substrate T-shaped microstructure electrode modulator requires wet etching of the substrate through small holes that are usually only a few microns wide between the T-shaped microstructure electrodes. It has high requirements for etching accuracy and time control, and may damage the prepared lithium niobate and T-shaped microstructure electrodes. It is costly and has a low yield. It is incompatible with existing mass production processes and is difficult to achieve large-scale wafer-level preparation. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an electro-optic modulator based on a silicon-based heterogeneous integrated thin film lithium niobate platform. The electro-optic modulator combines the advantages of a T-shaped microstructure electrode lithium niobate electro-optic modulator and a silicon-based heterogeneous integrated lithium niobate platform. While maintaining the advantages of high electro-optic bandwidth and low power consumption of the T-shaped microstructure electrode lithium niobate electro-optic modulator, it has the capability of wafer-level preparation and large-scale integration based on mature silicon-based optoelectronic devices.

[0005] The present invention provides an electro-optic modulator based on a silicon-based heterogeneous integrated thin film lithium niobate platform, comprising a first silicon-based multimode interference coupler, a first silicon-lithium niobate interlayer coupler, a T-shaped microstructure electrode, a lithium niobate modulation arm, a second silicon-lithium niobate interlayer coupler and a second silicon-based multimode interference coupler connected in sequence; the silicon-lithium niobate interlayer coupler comprises, from top to bottom, a lithium niobate ridge waveguide, a silicon dioxide buffer layer, a silicon waveguide and a substrate.

[0006] Furthermore, there is a cavity between the silicon dioxide layer and the substrate.

[0007] Furthermore, the lithium niobate ridge waveguide is located above the cavity.

[0008] Furthermore, the T-shaped microstructure electrodes are located on both sides of the lithium niobate ridge waveguide.

[0009] Furthermore, the substrate is a high-resistance silicon substrate or a silicon-on-insulator wafer.

[0010] Furthermore, the T-shaped microstructure electrode is made of metal.

[0011] Furthermore, the method for preparing the silicon-lithium niobate interlayer coupler comprises the following steps:

[0012] (1) preparing a silicon waveguide pattern on a substrate and depositing a silicon dioxide buffer layer;

[0013] (2) etching the silicon dioxide buffer layer and the substrate by dry etching to form a cavity;

[0014] (3) bonding thin film lithium niobate layer;

[0015] (4) etching the lithium niobate thin film to prepare a lithium niobate waveguide pattern to form a lithium niobate ridge waveguide;

[0016] (5) An electrode is deposited on top of the lithium niobate ridge waveguide to form a T-shaped microstructure electrode.

[0017] Beneficial Effects

[0018] The present invention combines the advantages of the T-shaped microstructure electrode lithium niobate electro-optic modulator and the advantages of the silicon-based heterogeneous integrated lithium niobate platform. While maintaining the high electro-optic bandwidth and low power consumption advantages of the T-shaped microstructure electrode lithium niobate electro-optic modulator, it has the capabilities of wafer-level preparation and large-scale integration based on mature silicon-based optoelectronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the electro-optic modulator of the present invention.

[0020] Figure 2 Schematic diagram of the interlayer coupler of the present invention.

[0021] Figure 3 It is a cross-sectional view of the electro-optic modulator of the present invention.

[0022] Figure 4 Schematic diagram of bonding between silicon-based wafer and thin-film lithium niobate.

[0023] FIG5 is a simulation result of the electro-optic modulator of the present invention; wherein a is the electro-optic bandwidth, and b is the microwave refractive index.

[0024] Figure 6 The figure is a flow chart of the preparation of the electro-optic modulator of the present invention. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0026] Example 1

[0027] Depend on Figure 1 As shown, this embodiment provides an electro-optic modulator based on a silicon-based heterogeneous integrated thin film lithium niobate platform, including a first silicon-based multimode interference coupler, a first silicon-lithium niobate interlayer coupler, a T-shaped microstructure electrode, a lithium niobate modulation arm, a second silicon-lithium niobate interlayer coupler, and a second silicon-based multimode interference coupler connected in sequence; the silicon-lithium niobate interlayer coupler includes a lithium niobate ridge waveguide, a silicon dioxide buffer layer, a silicon waveguide, and a substrate from top to bottom. The optical signal enters the electro-optic modulator and is split by the first silicon-based multimode interference coupler. The two optical signals are respectively input into the modulation arm of the lithium niobate ridge waveguide through the first silicon-lithium niobate interlayer coupler, as shown in FIG. Figure 2 As shown, the optical signal is modulated by the T-shaped microstructure electrode and input into the silicon waveguide by the second silicon-lithium niobate interlayer coupler, and then beam-combined by the second silicon-based multimode interference coupler and input into other silicon-based devices to achieve large-scale integration. In the electrode part, a metal-made T-shaped microstructure electrode is used to obtain a large electro-optical bandwidth and a high modulation rate. The T-shaped microstructure electrode is made of metal (such as aluminum, gold, silver, etc.).

[0028] Furthermore, the substrate is a high-resistance silicon substrate or a silicon-on-insulator wafer.

[0029] Furthermore, the method for preparing the silicon-lithium niobate interlayer coupler is as follows: Figure 6 As shown, the following steps are included:

[0030] (1) preparing a silicon waveguide pattern on a substrate and depositing a silicon dioxide buffer layer;

[0031] (2) etching the silicon dioxide buffer layer and the substrate by dry etching to form a cavity;

[0032] (3) bonding thin film lithium niobate layer;

[0033] (4) etching the lithium niobate thin film to prepare a lithium niobate waveguide pattern to form a lithium niobate ridge waveguide;

[0034] (5) An electrode is deposited on top of the lithium niobate ridge waveguide to form a T-shaped microstructure electrode.

[0035] In order to achieve the electro-optical rate and characteristic impedance matching between the T-shaped microstructure electrode and the lithium niobate ridge waveguide, before bonding the thin film lithium niobate layer, the substrate is dry-etched to hollow out the silicon substrate to form a cavity, such as Figure 3 After etching, the thin film lithium niobate is bonded to the silicon wafer, as shown in Figure 4 After bonding, a ridge waveguide is prepared by etching a thin film of lithium niobate at the center of the corresponding silicon substrate cavity, and a metal electrode is prepared using a deposition process. A T-shaped microstructure electrode is prepared above the silicon substrate cavity portion, such as Figure 1 In the lower right corner, the microwave rate and characteristic impedance of the electrode are efficiently controlled. By using finite element software to simulate the high-frequency performance of a 20 mm long device, the microwave refractive index is 2.25 and the electro-optical bandwidth is greater than 110 GHz. Figure 5a and Figure 5b shown.

[0036] According to the simulation results, the present invention combines the advantages of T-shaped microstructure electrode lithium niobate electro-optic modulator and silicon-based heterogeneous integrated lithium niobate platform. While maintaining the advantages of high electro-optic bandwidth and low power consumption of T-shaped microstructure electrode lithium niobate electro-optic modulator, it has wafer-level preparation and large-scale integration capabilities based on mature silicon-based optoelectronic devices.

Claims

1. An electro-optic modulator based on a silicon-based heterogeneous integrated thin film lithium niobate platform, characterized in that: It includes a first silicon-based multimode interference coupler, a first silicon-lithium niobate interlayer coupler, a T-shaped microstructure electrode, a lithium niobate modulation arm, a second silicon-lithium niobate interlayer coupler and a second silicon-based multimode interference coupler connected in sequence; the silicon-lithium niobate interlayer coupler includes a lithium niobate ridge waveguide, a silicon dioxide buffer layer, a silicon waveguide and a substrate from top to bottom.

2. The electro-optic modulator according to claim 1, characterized in that: There is a cavity between the silicon dioxide layer and the substrate.

3. The electro-optic modulator according to claim 2, characterized in that: The lithium niobate ridge waveguide is located above the cavity.

4. The electro-optic modulator according to claim 1 or 3, characterized in that: The T-shaped microstructure electrodes are located on both sides of the lithium niobate ridge waveguide.

5. The electro-optic modulator according to claim 1, characterized in that: The substrate is a high-resistance silicon substrate or a silicon-on-insulator wafer.

6. The electro-optic modulator according to claim 1, characterized in that: The T-shaped microstructure electrode is made of metal.

7. The electro-optic modulator according to claim 1, characterized in that: The method for preparing the silicon-lithium niobate interlayer coupler comprises the following steps: (1) preparing a silicon waveguide pattern on a substrate and depositing a silicon dioxide buffer layer; (2) etching the silicon dioxide buffer layer and the substrate by dry etching to form a cavity; (3) bonding thin film lithium niobate layer; (4) etching the lithium niobate thin film to prepare a lithium niobate waveguide pattern to form a lithium niobate ridge waveguide; (5) An electrode is deposited on top of the lithium niobate ridge waveguide to form a T-shaped microstructure electrode.

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