Silicon dioxide-silicon nitride-lead zirconate titanate hybrid waveguide electro-optical modulator

Abstract

The invention discloses a silicon dioxide-silicon nitride-lead zirconate titanate hybrid waveguide electro-optical modulator, and belongs to the technical field of optical modulators. The electro-optical modulator is composed of a silicon-based substrate, a lower wrapping layer, an optical waveguide core layer, a spacing layer and a metal electrode from bottom to top in sequence. The optical waveguide core layer is wrapped between the lower wrapping layer and the spacing layer, adopts a loaded strip-shaped waveguide structure and is composed of a flat-plate-shaped lower optical waveguide core layer and a strip-shaped upper optical waveguide core layer; the strip-shaped upper optical waveguide core layer is of an MZI type structure and is composed of an input straight waveguide, a 1 * 2 input multi-mode interference coupler, a first input S bent waveguide, a second input S bent waveguide, a first modulation straight waveguide, a second modulation straight waveguide, a first output S bent waveguide, a second output S bent waveguide, a 2 * 1 output multi-mode interference coupler and an output straight waveguide. According to the invention, the high-speed electro-optical modulator with a silicon dioxide-silicon nitride-lead zirconate titanate mixed waveguide structure, which has low loss and high modulation efficiency, is finally obtained.

Description

Technical Field

[0001] This invention belongs to the field of optical modulator technology, specifically relating to a silicon dioxide-silicon nitride-lead zirconate titanate hybrid waveguide optical modulator. Background Technology

[0002] With the rapid development of big data, AI, 6G communication, cloud computing, and the Internet of Things, the demand for data traffic is increasing dramatically, driving the optical communication field towards higher speeds and greater integration. As a core component of optical modules, electro-optic modulators play a crucial role in the entire optical communication network, and their performance affects the data transmission capability of the entire optical communication system. With increasing market demand, higher requirements are being placed on the modulation efficiency, bandwidth, and transmission loss of electro-optic modulators.

[0003] Currently, silicon-based platforms are the most widely used photonic platforms, possessing mature and stable fabrication processes, good compatibility with microelectronic CMOS platforms, and low-loss advantages in their material systems, making them extensively studied by researchers. However, due to the inherent material properties of silicon, it lacks first-order electro-optic characteristics (Pockels effect), which cannot meet the future demands for high speed and high bandwidth. In recent years, ferroelectric domain electro-optic materials have emerged, such as lithium niobate (LiNbO3), lithium tantalate (LiTaO3), and lanthanum-modified lead zirconate titanate (PbO3). 1-x La x (Zr) y Ti 1-y )O3, abbreviated as PLZT), lead zirconate titanate (PbZr) x Ti 1-x Materials such as O3 (PZT) and barium titanate (BaTiO3, BTO) have higher electro-optic coefficients and excellent optical transparency at optical communication wavelengths, making them ideal materials for manufacturing electro-optic modulators. High-performance electro-optic modulators, electro-optic switches and other electro-optic devices can be developed using these materials.

[0004] The half-wave voltage-length product (Vπ·L) of an electro-optic modulator is a crucial parameter. In MZI-type modulators, besides the inherent electro-optic properties of the material, it primarily depends on the spacing between the modulation electrodes and the electro-optic overlap factor. Smaller electrode spacing results in a larger electro-optic overlap factor and higher modulation efficiency. Ideal modulation parameters require a trade-off between the minimum electrode spacing and the electro-optic overlap factor. However, as the electrode spacing decreases to a certain value, some optical field couples into the surface plasma polariton (SPP) mode excited at the interface between the metal electrode and the planar layer, causing lateral broadening and leakage of the optical field, resulting in strong optical absorption loss. Therefore, a trade-off must be struck between modulation efficiency and loss. Summary of the Invention

[0005] To achieve a low-loss, high-modulation-efficiency electro-optic modulator, this invention combines the mature and advanced fabrication process of the silicon-based photonics platform with high-performance electro-optic materials, and proposes a silicon dioxide-silicon nitride-lead zirconate titanate hybrid waveguide electro-optic modulator, in which a spacer layer exists between the optical waveguide core layer and the metal electrode, effectively suppressing the high loss caused by the SPP mode, and finally obtaining a low-loss, high-modulation-efficiency silicon dioxide-silicon nitride-lead zirconate titanate hybrid waveguide high-speed electro-optic modulator.

[0006] The silicon dioxide-silicon nitride-lead zirconate titanate hybrid waveguide optical modulator of the present invention comprises, from bottom to top, a silicon substrate (14), a lower cladding layer (15), an optical waveguide core layer, a spacer layer (18), and a metal electrode (19); the optical waveguide core layer is encased between the lower cladding layer (15) and the spacer layer (18); as shown in the attached figure. Figure 1As shown, the optical waveguide core layer adopts a loaded strip waveguide structure, which consists of a planar lower optical waveguide core layer (16) and a strip upper optical waveguide core layer (17). The strip upper optical waveguide core layer (17) is an MZI type structure, consisting of an input straight waveguide (1), a 1×2 input multimode interference coupler (MMI) (2), a first input S-bend waveguide (3), a second input S-bend waveguide (4), a first modulation straight waveguide (5), and a second modulation straight waveguide (6). The system consists of a first output S-bend waveguide (7), a second output S-bend waveguide (8), a 2×1 output multimode interference coupler (9), and an output straight waveguide (10); a first input S-bend waveguide (3), a first modulation straight waveguide (5), and a first output S-bend waveguide (7) are connected sequentially, and a second input S-bend waveguide (4), a second modulation straight waveguide (6), and a second output S-bend waveguide (8) are connected sequentially; the first modulation straight waveguide (5) and the second modulation straight waveguide (6) are arranged parallel to each other to form a modulation region; the strip-shaped upper optical wave... The core layer (17) is a left-right symmetrical structure about the optical transmission direction in the input straight waveguide (1) and the output straight waveguide (10), and also a front-back symmetrical structure about the modulation region; the output end of the input straight waveguide (1) is connected to the input end of the 1×2 input multimode interference coupler (2), and the two output ends of the 1×2 input multimode interference coupler (2) are respectively connected to the input ends of the first input S-bend waveguide (3) and the second input S-bend waveguide (4); the outputs of the first output S-bend waveguide (7) and the second output S-bend waveguide (8) The two input terminals of the 2×1 output multimode interference coupler (9) are connected to the output straight waveguide (10). The output terminal of the 2×1 output multimode interference coupler (9) is connected to the output straight waveguide (10). On the spacer layer (18) outside the first modulation straight waveguide (5), between the first modulation straight waveguide (5) and the second modulation straight waveguide (6), and outside the second modulation straight waveguide (6), there are parallel first ground metal electrode (11), signal metal electrode (12) and second ground metal electrode (13) separated by the spacer layer (18).

[0007] To achieve a larger bandwidth and greater process tolerance, the beam splitter / combiner in this invention employs a multimode interference coupler, wherein the structure of the 1×2 input multimode interference coupler (2) is shown in the attached figure. Figure 3As shown, it is composed of an MMI input straight waveguide (20), an input wedge converter (21), a multimode interference region (22), a first output wedge converter (23), a second output wedge converter (24), a first MMI output straight waveguide (25), and a second MMI output straight waveguide (26). Along the optical transmission direction in the input straight waveguide (1) and the output straight waveguide (10), the width of the input wedge converter (21) increases linearly from narrow, while the width of the first output wedge converter (23) and the second output wedge converter (24) decreases linearly from wide. The input straight waveguide (20) and the input wedge converter (21) are connected in sequence and serve as the input end of a 1×2 input multimode interference coupler (2). The first output wedge converter... The wedge converter (23) and the first MMI output straight waveguide (25) are connected in sequence, and the second output wedge converter (24) and the second MMI output straight waveguide (26) are connected in sequence to serve as the two output terminals of the 1×2 input multimode interference coupler (2); the 1×2 input multimode interference coupler (2) is a left-right symmetrical structure about the light transmission direction in the input straight waveguide (1) and the output straight waveguide (10), and the input wedge converter (21), the first output wedge converter (23) and the second output wedge converter (24) are symmetrical structures about their own central axis; the 2×1 output multimode interference coupler (9) and the 1×2 input multimode interference coupler (2) are front-back symmetrical structures about the modulation region.

[0008] As attached Figure 2 As shown, they are respectively Figure 1 Cross-sectional diagrams at positions a-a' and b-b'. (See diagram below.) Figure 2 As shown in (a), the device consists of a silicon substrate (14), a lower cladding layer (15), a lower optical waveguide core layer (16), an upper optical waveguide core layer (17), and a spacer layer (18) from bottom to top. The upper optical waveguide core layer (17) at this point corresponds to... Figure 1 The input straight waveguide (1) in the middle; such as Figure 2 As shown in (b), the device consists of a silicon substrate (14), a lower cladding layer (15), a lower waveguide core layer (16), an upper waveguide core layer (17), a spacer layer (18), and a metal electrode (19) from bottom to top. The upper waveguide core layer (17) at this point corresponds to... Figure 1 The first modulation straight waveguide (5) and the second modulation straight waveguide (6) are connected, with the metal electrode (19) corresponding to them. Figure 1 The first grounding metal electrode (11), the signal metal electrode (12), and the second grounding metal electrode (13) are in the middle.

[0009] The silicon substrate (14) may be one of silicon or silicon nitride; the lower cladding layer (15) may be one of low refractive index silicon dioxide or polymer; the upper waveguide core layer (17) may be one of high refractive index silicon nitride, silicon, doped silicon dioxide, or polymer; the lower waveguide core layer (16) may be made of ferroelectric material, such as lead zirconate titanate, lanthanum-modified lead zirconate titanate, or barium titanate; the spacer layer (18) may be one of the same low refractive index silicon dioxide material or polymer as the lower cladding layer (15); and the metal electrode (19) may be one of aluminum, gold, silver, tungsten, or titanium.

[0010] The working principle of the silicon dioxide-silicon nitride-lead zirconate titanate hybrid waveguide optical modulator of the present invention is as follows:

[0011] When the device is working, 1550nm light is input through the input straight waveguide (1) and then enters the MMI input straight waveguide (20) and input wedge converter (21) of the 1×2 input multimode interference coupler (2). Under the self-image principle of the multimode interference coupler, the input light is divided into two parts with equal optical power, which are output from the first output wedge converter (23) and the first MMI output straight waveguide (25), the second output wedge converter (24) and the second MMI output straight waveguide (26) of the 1×2 input multimode interference coupler (2), respectively. Then, they enter the first input S-bend waveguide (3) and the second input S-bend waveguide (4), and then enter the first modulation straight waveguide (5) and the second modulation straight waveguide (6), respectively. The first ground metal electrode (11) and the second ground metal electrode (26) are connected to the first ground metal electrode (20). 13) Simultaneously grounded, a signal voltage is applied to the signal metal electrode (12), and the polarization directions of the two first modulation straight waveguides (5) and the second modulation straight waveguide (6) are different; when the signal voltage is positive or negative, the refractive index of the first modulation straight waveguide (5) or the second modulation straight waveguide (6) changes due to the Pockels effect, and a refractive index difference is generated between the two modulation straight waveguides, which ultimately leads to a phase difference in the light in the first modulation straight waveguide (5) and the second modulation straight waveguide (6); the two beams of light after electro-optic modulation enter the first output S-bend waveguide (7) and the second output S-bend waveguide (8) at the output end respectively, and then enter the 2×1 output multimode interference coupler (9) for beam combining, and finally output by the output straight waveguide (10), thereby realizing the intensity modulation of the beam.

[0012] The innovation of this invention compared with the prior art lies in:

[0013] 1) This invention uses ferroelectric materials such as lead zirconate titanate, lanthanum-modified lead zirconate titanate, and barium titanate as the lower optical waveguide core layer for electro-optic modulation. Compared with traditional electro-optic materials, these materials have a high electro-optic coefficient, which is beneficial to reducing the driving voltage.

[0014] 2) This invention heterogeneously integrates silicon-based materials and ferroelectric materials, which is beneficial for realizing multifunctional, low-power, and large-scale integrated photonic devices;

[0015] 3) The invention introduces a spacer layer, which is beneficial for suppressing the SPP mode between the metal electrode and the optical waveguide, thereby realizing a low-loss, high-modulation-efficiency electro-optic modulator. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the optical waveguide core layer and electrode structure of a silicon dioxide-silicon nitride-lead zirconate titanate hybrid waveguide optical modulator according to the present invention.

[0017] Figure 2 This is a cross-sectional schematic diagram of a silicon dioxide-silicon nitride-lead zirconate titanate hybrid waveguide optical modulator according to the present invention. Figure 2 (a) is Figure 1 A schematic diagram of the cross-section at position a-a'. Figure 2 (b) is Figure 1 A schematic diagram of the cross-section at position b-b';

[0018] Figure 3 This is a schematic diagram of the 1×2 input multimode interference coupler described in this invention;

[0019] Figure 4 This is the transmission spectrum of the 1×2 input multimode interference coupler described in this invention;

[0020] Figure 5 This is the transmission optical field diagram of the 1×2 input multimode interference coupler described in this invention;

[0021] Figure 6 This is a graph showing the transmission loss of the modulation region of a silicon dioxide-silicon nitride-lead zirconate titanate hybrid waveguide as a function of electrode spacing, as described in this invention.

[0022] Figure 7 The graph shows the modulation efficiency of a silicon dioxide-silicon nitride-lead zirconate titanate hybrid waveguide as a function of electrode spacing, as described in this invention.

[0023] Figure 8 This is a graph showing the variation of the electro-electric transmission parameters of the modulation region with the frequency of transmitted light in a silicon dioxide-silicon nitride-lead zirconate titanate hybrid waveguide optical modulator according to the present invention.

[0024] Figure 9 This is a process flow diagram of the fabrication process of a silicon dioxide-silicon nitride-lead zirconate titanate hybrid waveguide optical modulator according to the present invention. Detailed Implementation

[0025] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The embodiments described below are not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0026] To better describe this embodiment, some components in some of the accompanying drawings may be omitted, enlarged, or reduced; therefore, the drawings do not represent the actual size of the device.

[0027] Example 1

[0028] The present invention discloses a silicon dioxide-silicon nitride-lead zirconate titanate hybrid waveguide optical modulator, which, from bottom to top, consists of a silicon substrate, a lower cladding layer, an optical waveguide core layer, a spacer layer, and metal electrodes. The optical waveguide core layer adopts a loaded strip structure, consisting of a planar lower optical waveguide core layer and a strip-shaped upper optical waveguide core layer. The spacer layer is uniformly deposited above the optical waveguide core layer. The optical waveguide core layer is wrapped by the lower cladding layer and the spacer layer. The strip-shaped upper optical waveguide core layer and the discrete metal electrodes are separated by the spacer layer.

[0029] like Figure 1 As shown, the input straight waveguide (1), the first input S-bend waveguide (3), the second input S-bend waveguide (4), the first output S-bend waveguide (7), the second output S-bend waveguide (8), the output straight waveguide (10), the first modulation straight waveguide (5), and the second modulation straight waveguide (6) all have an equal width of 1.5 μm. Except for the wedge waveguide and the multimode interference coupler, the lengths of the other waveguides have no special requirements, as long as they can be properly connected. This embodiment uses rectangular ground-signal-ground (GSG) electrodes, each with a width of 40 μm, a length of 5 mm, and an electrode spacing of 4.3 μm.

[0030] like Figure 2As shown, the silicon substrate (14) can be made of silicon or silicon nitride. In this embodiment, silicon is selected, and its thickness is 500 μm. The lower cladding layer (15) can be made of silicon dioxide or polymer with a lower refractive index. In this embodiment, silicon dioxide is selected as the lower cladding layer, which has a refractive index of 1.444 at a wavelength of 1550 nm and a thickness of 2 μm. The optical waveguide core layer and spacer layer of the modulator of the present invention are integrated using a mixture of three materials. The upper optical waveguide core layer (17) can be made of silicon nitride, silicon, doped silicon dioxide, polymer, etc., which have a higher refractive index. In this embodiment, silicon nitride is selected, which has a refractive index of 1.444 at a wavelength of 1550 nm and a thickness of 2 μm. The refractive index of the lower cladding layer (16) is 1.915 and the thickness is 0.2 μm. The lower waveguide core layer (16) uses ferroelectric materials, such as lead zirconate titanate, lanthanum-modified lead zirconate titanate, barium titanate, etc. In this embodiment, lead zirconate titanate (PZT) is used, which has a refractive index of 2.37 at a wavelength of 1550 nm and a thickness of 0.3 μm. The spacer layer (18) uses the same silicon dioxide material as the lower cladding layer (15), which has a refractive index of 1.444 at a wavelength of 1550 nm and a thickness of 50 nm. The metal electrode (19) can be one of aluminum, gold, silver, tungsten, or titanium. In this embodiment, aluminum electrode is used, with a thickness of 0.4 μm.

[0031] like Figure 3 As shown, the thickness of the 1×2 input multimode interference coupler is 0.2μm. The lengths of the MMI input straight waveguide (20), the first MMI output straight waveguide (25), and the second MMI output straight waveguide (26) are equal at 10μm, and the widths are equal at 1.5μm. The length of the multimode interference region (22) is 73μm, and the width is 10μm. The lengths of the input wedge converter (21), the first output wedge converter (23), and the second output wedge converter (24) are equal at 10μm. Along the optical transmission direction in the input straight waveguide (1) and the output straight waveguide (10), the width of the input wedge converter (21) is linearly varied from 1.5μm to 3.5μm, and the widths of the first output wedge converter (23) and the second output wedge converter (24) are linearly varied from 3.5μm to 1.5μm. The distance between the central axes of the first output wedge converter (23) and the second output wedge converter (24) is 5μm.

[0032] like Figure 4 The image shows the transmission spectrum of the multimode interference coupler used in this invention. The transmission loss is as low as 3.07 dB under a 1550 nm light source, and the transmission loss of both channels is less than 3.1 dB in the wavelength range of 1500 nm to 1600 nm.

[0033] like Figure 5The figure shows the transmission optical field diagram of the multimode interference coupler used in this invention. As can be seen from the figure, the transmission optical field is symmetrical about the central axis, and the two output channels exhibit uniform beam splitting, resulting in good transmission performance.

[0034] like Figure 6 The figure shows the variation of transmission loss in the modulation region of the modulator of the present invention with electrode spacing. As can be seen from the figure, the transmission loss in the modulation region decreases with increasing electrode spacing. Simultaneously, the addition of the silicon dioxide spacer layer can significantly reduce transmission loss and suppress the SPP mode. Here, with a transmission loss upper limit of 1 dB / cm, the minimum allowable electrode spacing decreases from 6.9 μm to 4.3 μm before and after adding the silicon dioxide spacer layer, a decrease of nearly 40%.

[0035] like Figure 7 The figure shows the modulation efficiency of the modulator of the present invention as a function of electrode spacing. As can be seen from the figure, under the condition of transmission loss <1dB / cm, the device can achieve a smaller Vπ·L after adding a silicon dioxide spacer layer; when the electrode spacing is 6.9μm, Vπ·L = 0.40178 V·cm; when the electrode spacing is 4.3μm, Vπ·L = 0.34292 V·cm.

[0036] like Figure 8 The figure shows the variation of the electro-electric transmission parameters of the modulation region of the present invention with frequency. In the modulation frequency range of 70 GHz, the transmission parameter attenuation is less than 2.4 dB, which shows that the modulator can work normally in the frequency range of 0 ~ 70 GHz.

[0037] like Figure 9 As shown, the method for fabricating the electro-optic modulator of the present invention is as follows:

[0038] First, a silicon nitride layer is deposited on a cleaned silicon dioxide wafer with a 200 nm thick PZT film using physical vapor deposition (PVD), and then polished to a thickness of 300 nm using chemical mechanical polishing (CMP). Next, photoresist 1 (RD2400) is spin-coated onto the silicon nitride layer, followed by a first photolithography step to form a mask. Then, the mask pattern is transferred to the silicon nitride layer using inductively coupled plasma etching (ICP) to form the upper waveguide core layer. Next, a 50 nm thick silicon dioxide film is deposited as a spacer layer. Then, a 400 nm thick aluminum metal layer is deposited on the silicon dioxide spacer layer using PVD. Then, photoresist 2 (AZ nLOF 2035) is spin-coated onto the metal layer, followed by a second photolithography step to form a mask. Finally, a first ground metal electrode, a signal metal electrode, and a second ground metal electrode are fabricated on the spacer layer and between the upper waveguide core layer using metal lift-off, thus obtaining the electro-optic modulator.

Claims

1. A silicon dioxide-silicon nitride-lead zirconate titanate hybrid waveguide optical modulator, characterized in that: From bottom to top, it consists of a silicon substrate (14), a lower cladding layer (15), an optical waveguide core layer, a spacer layer (18), and a metal electrode (19). The optical waveguide core layer is encased between the lower cladding layer (15) and the spacer layer (18). The optical waveguide core layer adopts a loaded strip waveguide structure, consisting of a planar lower optical waveguide core layer (16) and a strip-shaped upper optical waveguide core layer (17). The strip-shaped upper optical waveguide core layer (17) is an MZI type structure, consisting of an input straight waveguide (1), a 1×2 input multimode interference coupler (2), a first input S-bend waveguide (3), and a second... The system consists of a two-input S-bend waveguide (4), a first modulation straight waveguide (5), a second modulation straight waveguide (6), a first output S-bend waveguide (7), a second output S-bend waveguide (8), a 2×1 output multimode interference coupler (9), and an output straight waveguide (10). The first input S-bend waveguide (3), the first modulation straight waveguide (5), and the first output S-bend waveguide (7) are connected sequentially, and the second input S-bend waveguide (4), the second modulation straight waveguide (6), and the second output S-bend waveguide (8) are connected sequentially. The first modulation straight waveguide (5) and the second modulation straight waveguide (8) are connected sequentially. (6) They are arranged in parallel to each other to form a modulation zone; the strip-shaped upper optical waveguide core layer (17) is a left-right symmetrical structure about the optical transmission direction in the input straight waveguide (1) and the output straight waveguide (10), and is also a front-back symmetrical structure about the modulation zone; the output end of the input straight waveguide (1) is connected to the input end of the 1×2 input multimode interference coupler (2), and the two output ends of the 1×2 input multimode interference coupler (2) are respectively connected to the input ends of the first input S-bend waveguide (3) and the second input S-bend waveguide (4); the first output S-bend waveguide (7) and the second output The output of the S-curved waveguide (8) is connected to the two inputs of the 2×1 output multimode interference coupler (9), and the output of the 2×1 output multimode interference coupler (9) is connected to the output straight waveguide (10). On the spacer layer (18) outside the first modulation straight waveguide (5), between the first modulation straight waveguide (5) and the second modulation straight waveguide (6), and outside the second modulation straight waveguide (6), there are parallel first ground metal electrode (11), signal metal electrode (12) and second ground metal electrode (13) separated by the spacer layer (18).

2. The silicon dioxide-silicon nitride-lead zirconate titanate hybrid waveguide optical modulator as described in claim 1, characterized in that: The 1×2 input multimode interference coupler (2) is composed of an MMI input straight waveguide (20), an input wedge converter (21), a multimode interference region (22), a first output wedge converter (23) and a second output wedge converter (24), a first MMI output straight waveguide (25) and a second MMI output straight waveguide (26). Along the optical transmission direction in the input straight waveguide (1) and the output straight waveguide (10), the width of the input wedge converter (21) increases linearly from narrow, while the width of the first output wedge converter (23) and the second output wedge converter (24) decreases linearly from wide. The input straight waveguide (20) and the input wedge converter (21) are connected in sequence and serve as the input of the 1×2 input multimode interference coupler (2). The first output wedge converter (23) and the first MMI output straight waveguide (25) are connected in sequence, and the second output wedge converter (24) and the second MMI output straight waveguide (26) are connected in sequence as the two output terminals of the 1×2 input multimode interference coupler (2); the 1×2 input multimode interference coupler (2) is a left-right symmetrical structure about the optical transmission direction in the input straight waveguide (1) and the output straight waveguide (10), and the input wedge converter (21), the first output wedge converter (23) and the second output wedge converter (24) are symmetrical structures about their own central axis; the 2×1 output multimode interference coupler (9) and the 1×2 input multimode interference coupler (2) are front-back symmetrical structures about the modulation region.

3. The silicon dioxide-silicon nitride-lead zirconate titanate hybrid waveguide optical modulator as described in claim 2, characterized in that: The thickness of the 1×2 input multimode interference coupler is 0.2μm. The lengths of the MMI input straight waveguide (20), the first MMI output straight waveguide (25), and the second MMI output straight waveguide (26) are equal at 10μm, and the widths are equal at 1.5μm. The length of the multimode interference region (22) is 73μm, and the width is 10μm. The lengths of the input wedge converter (21), the first output wedge converter (23), and the second output wedge converter (24) are equal at 10μm. Along the optical transmission direction in the input straight waveguide (1) and the output straight waveguide (10), the width of the input wedge converter (21) is linearly varied from 1.5μm to 3.5μm, and the widths of the first output wedge converter (23) and the second output wedge converter (24) are linearly varied from 3.5μm to 1.5μm. The distance between the central axes of the first output wedge converter (23) and the second output wedge converter (24) is 5μm.

4. The silicon dioxide-silicon nitride-lead zirconate titanate hybrid waveguide optical modulator as described in claim 1, characterized in that: The silicon substrate (14) is one of silicon or silicon nitride; the lower cladding layer (15) is one of low-refractive-index silicon dioxide or polymer; the upper waveguide core layer (17) is one of high-refractive-index silicon nitride, silicon, doped silicon dioxide, or polymer; the lower waveguide core layer (16) is one of lead zirconate titanate, lanthanum-modified lead zirconate titanate, or barium titanate; the spacer layer (18) is one of the same low-refractive-index silicon dioxide material or polymer as the lower cladding layer (15); and the metal electrode (19) is one of aluminum, gold, silver, tungsten, or titanium.

5. The silicon dioxide-silicon nitride-lead zirconate titanate hybrid waveguide optical modulator as described in claim 1, characterized in that: The widths of the input straight waveguide (1), the first input S-bend waveguide (3), the second input S-bend waveguide (4), the first output S-bend waveguide (7), the second output S-bend waveguide (8), the output straight waveguide (10), the first modulation straight waveguide (5), and the second modulation straight waveguide (6) are all equal at 1.5 μm; the widths of the first ground metal electrode (11), the signal metal electrode (12), and the second ground metal electrode (13) are all 40 μm, the length is 5 mm, and the electrode spacing is 4.3 μm.

6. The silicon dioxide-silicon nitride-lead zirconate titanate hybrid waveguide optical modulator as described in claim 1, characterized in that: The thickness of the silicon substrate (14) is 500 μm; the thickness of the lower cladding layer (15) is 2 μm; the thickness of the upper waveguide core layer (17) is 0.2 μm; the thickness of the lower waveguide core layer (16) is 0.3 μm; the thickness of the spacer layer (18) is 50 nm; and the thickness of the metal electrode (19) is 0.4 μm.

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