A silicon-based Mach-Zehnder interferometer based on Y-branch symmetric structure

Abstract

The present invention relates to a silicon-based Mach-Zehnder interferometer based on a Y-branch symmetrical structure, comprising an input Y-branch waveguide and an output Y-branch waveguide, wherein the input Y-branch waveguide and the output Y-branch waveguide have the same structure, and the first output end of the input Y-branch waveguide is connected to the first input end of the output Y-branch waveguide through a first straight waveguide; the second output end of the input Y-branch waveguide is connected to one end of a first curved waveguide, the second input end of the output Y-branch waveguide is connected to one end of a second curved waveguide, and the other end of the first curved waveguide is connected to the other end of the second curved waveguide through the second straight waveguide; the first curved waveguide has the same structure as the second curved waveguide and is symmetrical along the midline of the second straight waveguide. The present invention can ensure stable transmission efficiency when the waveguide length changes from 10 μm to 40 μm.

Description

Technical Field

[0001] The invention relates to the technical field of silicon photonic devices, and in particular to a silicon-based Mach-Zehnder interferometer based on a Y-branch symmetric structure. Background Art

[0002] In the past few decades, due to the growing demand for optical communications and optical interconnection, silicon photonics technology has developed rapidly. At the same time, it has become a research hotspot in recent years due to its compact structure, low energy consumption, CMOS process compatibility and high integration. Among them, silicon-based Mach-Zehnder interferometer is the most basic silicon photonic device, which plays an important role in silicon-based wavelength division multiplexing technology, high-speed silicon-based modulators, optical switches, etc. The existing silicon-based Mach-Zehnder interferometer has unstable transmission efficiency and cannot meet the needs of different applications. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a silicon-based Mach-Zehnder interferometer based on a Y-branch symmetrical structure, which can ensure stable transmission efficiency when the waveguide length changes from 10 μm to 40 μm.

[0004] The technical solution adopted by the present invention to solve its technical problem is: providing a silicon-based Mach-Zehnder interferometer based on a Y-branch symmetrical structure, comprising an input Y-branch waveguide and an output Y-branch waveguide, the input Y-branch waveguide and the output Y-branch waveguide have the same structure, a first output end of the input Y-branch waveguide is connected to a first input end of the output Y-branch waveguide through a first straight waveguide; a second output end of the input Y-branch waveguide is connected to one end of a first curved waveguide, a second input end of the output Y-branch waveguide is connected to one end of a second curved waveguide, and the other end of the first curved waveguide is connected to the other end of the second curved waveguide through the second straight waveguide; the first curved waveguide has the same structure as the second curved waveguide and is symmetrical along the midline of the second straight waveguide.

[0005] The distance between the first output end and the second output end of the input Y-branch waveguide is equal to the length of the input end of the input Y-branch waveguide; the distance between the first input end and the second input end of the output Y-branch waveguide is equal to the length of the output end of the output Y-branch waveguide.

[0006] The distance between the first output end and the second output end of the input Y-branch waveguide is 5 μm; the distance between the first input end and the second input end of the output Y-branch waveguide is 5 μm.

[0007] The ratio of the distance between one end and the other end of the first curved waveguide to the length of the first curved waveguide is 3.05:4; the ratio of the distance between one end and the other end of the second curved waveguide to the length of the second curved waveguide is 3.05:4.

[0008] The distance between one end and the other end of the first curved waveguide is 3.05 μm; the length of the first curved waveguide is 4 μm; the distance between one end and the other end of the second curved waveguide is 3.05 μm; the length of the second curved waveguide is 4 μm.

[0009] The first curved waveguide and the second curved waveguide are both S-shaped curved waveguides.

[0010] The input Y-branch waveguide and the output Y-branch waveguide both adopt an arc-shaped design at the branch part.

[0011] Beneficial Effects

[0012] Due to the adoption of the above technical scheme, the present invention has the following advantages and positive effects compared with the prior art: the Y-branch waveguide of the present invention adopts an arc design in the branch part, and the S-shaped curved waveguide makes the overall width and loss of the device smaller, and through the optimization design of the parameters of the Y-branch and S-shaped curved waveguide, when the waveguide length changes from 10μm to 40μm, its transmission efficiency is above 96.3%, the interference spectrum is flat, the extinction ratio of the device is above 12dB, and when the waveguide thickness and width change within ±20nm, the performance remains stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the structure of the present invention;

[0014] Figure 2 It is a schematic diagram of the length of each part of the present invention;

[0015] Figure 3 It is a schematic diagram of the width of each part of the present invention;

[0016] Figure 4 It is a simulation result diagram of the present invention;

[0017] Figure 5 It is a simulation result diagram when the waveguide thickness in the present invention changes to ±10nm and ±20nm respectively;

[0018] Figure 6 It is a simulation result diagram when the waveguide width in the present invention changes to ±10nm and ±20nm respectively;

[0019] Figure 7 It is a manufacturing process flow chart of the present invention. DETAILED DESCRIPTION

[0020] 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.

[0021] The embodiments of the present invention relate to a silicon-based Mach-Zehnder interferometer based on a Y-branch symmetric structure, such as Figure 1 As shown, it includes an input Y-branch waveguide and an output Y-branch waveguide, the structures of the input Y-branch waveguide and the output Y-branch waveguide are the same, the first output end of the input Y-branch waveguide is connected to the first input end of the output Y-branch waveguide through the first straight waveguide; the second output end of the input Y-branch waveguide is connected to one end of the first curved waveguide, the second input end of the output Y-branch waveguide is connected to one end of the second curved waveguide, and the other end of the first curved waveguide is connected to the other end of the second curved waveguide through the second straight waveguide; the first curved waveguide and the second curved waveguide have the same structure, both are S-shaped curved waveguides, and are symmetrical along the midline of the second straight waveguide. The input Y-branch waveguide and the output Y-branch waveguide both adopt an arc design in the branch part.

[0022] The incident light input optical signal is divided into two identical light beams by the input Y-branch waveguide. The two light beams are transmitted in the upper and lower waveguides with different lengths respectively, and are recombined at the output port through the output Y-branch waveguide. The waveguides of different lengths can change the phase of the light beam and finally achieve interference.

[0023] In this embodiment, the distance between the first output end and the second output end of the input Y-branch waveguide is equal to the length of the input end of the input Y-branch waveguide; the distance between the first input end and the second input end of the output Y-branch waveguide is equal to the length of the output end of the output Y-branch waveguide. The ratio of the distance between one end and the other end of the first curved waveguide to the length of the first curved waveguide is 3.05:4; the ratio of the distance between one end and the other end of the second curved waveguide to the length of the second curved waveguide is 3.05:4.

[0024] like Figure 2 As shown, the length distribution of each device in this embodiment is as follows: the length of the input end of the input Y-branch waveguide is 5μm, and the length of the output end is 5.4μm; the length of the first curved waveguide is 4μm; the length of the second straight waveguide is L; the length of the second curved waveguide is 4μm; the length of the input end of the output Y-branch waveguide is 5.4μm, and the length of the output end is 5μm; the length of the first straight waveguide is 4μm+L+4μm.

[0025] like Figure 3As shown, the width distribution of each device in this embodiment is as follows: the distance between the first output end and the second output end of the input Y-branch waveguide is 5μm; the distance between one end and the other end of the first curved waveguide is 3.05μm; the distance between one end and the other end of the second curved waveguide is 3.05μm; the distance between the first input end and the second input end of the output Y-branch waveguide is 5μm.

[0026] When the wavelength is 1550nm, the transmission efficiency of the device changes with the length L as shown in Figure 4 As shown. Figure 4 It can be seen that when the waveguide length of the device changes from 10μm to 40μm, the interference pattern can be seen in the simulation results, the transmission efficiency of the device is above 96.3%, the interference spectrum is flat, and the extinction ratio of the device is above 12dB.

[0027] The device process tolerance simulation of this embodiment is as follows:

[0028] The waveguide thickness of the device in this embodiment is 220nm. When the waveguide thickness varies within ±10nm and ±20nm, the simulation results are as follows: Figure 5 As shown, it can be seen that the performance of the device remains stable when the top silicon thickness varies within ±20nm.

[0029] In this embodiment, the waveguide width of the device is 500nm. When the waveguide width varies within ±10nm and ±20nm, the simulation results are as follows: Figure 6 As shown, it can be seen that the performance of the device remains stable when the silicon waveguide width varies within ±20nm.

[0030] The manufacturing process of this embodiment is as follows Figure 7 As shown, starting from the SOI wafer (220nm top silicon, 2μm BOX layer), the first step is mask deposition, followed by spin-coating of photoresist for photolithography, then silicon etching, and finally deposition of the upper cladding layer.

[0031] It is not difficult to find that the Y-branch waveguide of the present invention adopts an arc design in the branch part, and the S-shaped bending waveguide makes the overall width and loss of the device smaller. Through the optimization design of the parameters of the Y-branch and S-shaped bending waveguide, when the waveguide length changes from 10μm to 40μm, its transmission efficiency is above 96.3%, the interference spectrum is flat, the extinction ratio of the device is above 12dB, and when the waveguide thickness and width change within ±20nm, the performance remains stable.

Claims

1. A silicon-based Mach-Zehnder interferometer based on a Y-branch symmetric structure, comprising an input Y-branch waveguide and an output Y-branch waveguide, wherein the input Y-branch waveguide and the output Y-branch waveguide have the same structure, characterized in that: The first output end of the input Y-branch waveguide is connected to the first input end of the output Y-branch waveguide through the first straight waveguide; the second output end of the input Y-branch waveguide is connected to one end of the first curved waveguide, the second input end of the output Y-branch waveguide is connected to one end of the second curved waveguide, and the other end of the first curved waveguide is connected to the other end of the second curved waveguide through the second straight waveguide; the first curved waveguide has the same structure as the second curved waveguide and is symmetrical along the midline of the second straight waveguide; the distance between the first output end and the second output end of the input Y-branch waveguide is equal to the length of the input end of the input Y-branch waveguide; the distance between the first input end and the second input end of the output Y-branch waveguide is equal to the length of the output end of the output Y-branch waveguide; the ratio of the distance between one end and the other end of the first curved waveguide to the length of the first curved waveguide is 3.05:4; the ratio of the distance between one end and the other end of the second curved waveguide to the length of the second curved waveguide is 3.05:4; both the first curved waveguide and the second curved waveguide are S-shaped curved waveguides.

2. The silicon-based Mach-Zehnder interferometer based on a Y-branch symmetric structure according to claim 1, characterized in that: The distance between the first output end and the second output end of the input Y-branch waveguide is 5 μm; the distance between the first input end and the second input end of the output Y-branch waveguide is 5 μm.

3. The silicon-based Mach-Zehnder interferometer based on a Y-branch symmetric structure according to claim 1, characterized in that: The distance between one end and the other end of the first curved waveguide is 3.05 μm; the length of the first curved waveguide is 4 μm; the distance between one end and the other end of the second curved waveguide is 3.05 μm; the length of the second curved waveguide is 4 μm.

4. The silicon-based Mach-Zehnder interferometer based on a Y-branch symmetric structure according to claim 1, characterized in that: The input Y-branch waveguide and the output Y-branch waveguide both adopt an arc-shaped design at the branch part.

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