Ultra-wideband electro-optic modulator integrating time-domain and frequency-domain equalization and method of manufacturing the same

Abstract

The application provides an ultra-wideband electro-optical modulator integrating time domain and frequency domain equalization and a preparation method thereof. The ultra-wideband electro-optical modulator comprises a silicon substrate, a silicon dioxide buried oxygen layer, a silicon nitride waveguide, a lead zirconate titanate thin film waveguide, a first coplanar waveguide electrode and a silicon dioxide embedding layer. The lead zirconate titanate thin film waveguide forms two parallel arms. A first section of the two parallel arms is forwardly polarized, and a second section is reversely polarized. The silicon nitride waveguide layer is arranged in a section of the first section adjacent to the second section. The first coplanar waveguide electrode is used for transmitting a microwave signal. The microwave signal is used for forward phase modulation of an optical signal in the forwardly polarized section and reverse phase modulation of the optical signal in the reversely polarized section. The silicon nitride waveguide introduces a time domain delay between the microwave signal and the optical signal. Based on the time domain delay, a microwave loss difference of the forward phase modulation and the reverse phase modulation of the optical signal is improved, so as to compensate for high-frequency modulation response attenuation and realize joint equalization of the time domain and the frequency domain.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optoelectronic integration and optical communication, and more particularly, to an ultra-wideband electro-optical modulator integrated with time-domain and frequency-domain equalization and a preparation method thereof. BACKGROUND

[0002] With the development of silicon photonics technology, on-chip high-speed modulators have become key devices for optical communication and optical interconnection systems. Traditional modulators based on silicon or silicon nitride waveguides mostly adopt a Mach-Zehnder structure to achieve light intensity control through phase modulation. However, due to weak electro-optic effect and limited bandwidth, the devices are prone to problems such as modulation depth decline and group delay mismatch under high-frequency conditions.

[0003] In recent years, hybrid integrated modulators prepared using strong electro-optic effect of lead zirconate titanate materials have attracted attention. Such materials have high electro-optic coefficients and good integrability. However, the existing structures still have problems such as insufficient matching of optical wave and microwave speed, phase distortion under high frequency, and uneven frequency-domain response, which limit the further improvement of system bandwidth. SUMMARY

[0004] Therefore, the present application provides an ultra-wideband electro-optical modulator integrated with time-domain and frequency-domain equalization and a preparation method thereof.

[0005] One aspect of the present application provides an ultra-wideband electro-optical modulator integrated with time-domain and frequency-domain equalization, which comprises, from bottom to top, a silicon substrate, a silicon dioxide buried oxygen layer, a silicon nitride waveguide, a lead zirconate titanate thin film waveguide, a first coplanar wave electrode, and a silicon dioxide embedding layer. The lead zirconate titanate thin film waveguide forms two parallel arms, the first section of the two parallel arms is positively polarized, and the second section is negatively polarized. The silicon nitride waveguide is arranged in the section of the first section that is adjacent to the second section. The first coplanar wave electrode is used to transmit a microwave signal. The microwave signal is used to positively phase modulate an optical signal in the positively polarized section of the lead zirconate titanate thin film waveguide and negatively phase modulate the optical signal in the negatively polarized section of the lead zirconate titanate thin film waveguide. The silicon nitride waveguide is coupled with the evanescent wave of the lead zirconate titanate thin film waveguide to introduce a controlled time-domain delay between the microwave signal and the optical signal after the positive phase modulation. When negatively phase modulating, based on the time-domain delay, the microwave loss difference between the positive phase modulation and the negative phase modulation of the optical signal is improved, thereby compensating for the attenuation of the high-frequency modulation response, and finally realizing the joint equalization of the time domain and the frequency domain to expand the modulation bandwidth.

[0006] According to the embodiment of the present application, the second co-planar waveguide electrode is arranged on the second section of the lead zirconate titanate thin film waveguide, and the silicon dioxide embedding layer covers the second co-planar waveguide electrode; the second co-planar waveguide electrode is used to apply a reverse voltage to the second section of the lead zirconate titanate thin film waveguide to perform reverse polarization before the ultra-wideband electro-optical modulator is enabled; and the first co-planar waveguide electrode is further used to apply a forward voltage to the lead zirconate titanate thin film waveguide to perform forward polarization before the ultra-wideband electro-optical modulator is enabled.

[0007] According to the embodiment of the present application, the two parallel arms are single-mode optical waveguide structures.

[0008] According to the embodiment of the present application, the material of the lead zirconate titanate thin film waveguide is lead zirconate titanate or lanthanum-doped lead zirconate titanate.

[0009] According to the embodiment of the present application, the first co-planar waveguide electrode and the second co-planar waveguide electrode are impedance-matched with the external microwave transmission line.

[0010] Another aspect of the present application provides a preparation method applied to the integrated time-domain and frequency-domain equalized ultra-wideband electro-optical modulator according to any one of the above aspects, including: forming a silicon dioxide embedding layer on a silicon substrate; depositing a silicon nitride waveguide layer on the silicon dioxide embedding layer, patterning by a photolithography and etching process to form a silicon nitride waveguide; locally depositing and patterning lead zirconate titanate thin film on preset sections of the two parallel arms to form a lead zirconate titanate thin film waveguide including the two parallel arms; depositing and patterning a first metal layer on the lead zirconate titanate thin film waveguide to form a first co-planar waveguide electrode; and depositing a silicon dioxide embedding layer on the substrate on which the first co-planar waveguide electrode is formed.

[0011] According to the embodiment of the present application, in the step of depositing the lead zirconate titanate thin film, lanthanum series elements are doped into the lead zirconate titanate thin film to form a lanthanum-doped lead zirconate titanate thin film.

[0012] According to the embodiment of the present application, in the step of forming the two parallel arms, the two parallel arms are prepared as single-mode optical waveguide structures by controlling the photolithography and etching process.

[0013] According to the embodiment of the present application, the method further includes: depositing a silicon dioxide isolation layer on the silicon nitride waveguide layer before depositing the lead zirconate titanate thin film waveguide.

[0014] According to the embodiment of the present application, the method further includes: depositing and patterning a second metal layer downstream of the lead zirconate titanate thin film waveguide to form a second co-planar waveguide electrode before depositing the silicon dioxide embedding layer.

[0015] According to the embodiment of the present application, because the technical means of integrating the time domain and frequency domain equalizers and the electro-optical modulator on the chip is adopted, the technical problems of system complexity, long signal path, easy reflection and distortion caused by the traditional modulator due to the dependence on external equalization circuit are at least partially overcome, and the technical effects of simplifying the peripheral circuit, shortening the signal path, reducing signal reflection and distortion, and realizing device miniaturization are achieved.

[0016] According to the embodiment of the present application, because the technical means of mixing and integrating the lead zirconate titanate thin film based on the silicon substrate, the silicon dioxide buried oxygen layer and the silicon nitride waveguide layer is adopted, the technical problems of difficulty in compatibility of strong electro-optical materials and standard silicon optical process, and difficulty in large-scale integration of the modulator are at least partially overcome, and the technical effects of ensuring compatibility of the device with mainstream silicon optical process, and being suitable for realizing large-scale and high-performance integration on a silicon-based photonic chip are achieved.

[0017] According to the embodiment of the present application, because the joint equalization technical means of introducing a controlled time domain delay through a velocity mismatch region, and utilizing a reverse modulation region to compensate the phase of forward modulation is adopted, the technical problem of limited bandwidth caused by high-frequency modulation response attenuation of the traditional traveling wave electrode modulator is at least partially overcome, and the technical effect of significantly widening the 3 dB bandwidth of the modulator, breaking through the traditional speed limit is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0018] The above and other objects, features and advantages of the present application will become more apparent from the following description of the embodiments of the present application taken in conjunction with the accompanying drawings, in which:

[0019] Figure 1 A plan view of the integrated time domain and frequency domain equalized ultra-wideband electro-optical modulator according to the embodiment of the present application is schematically shown;

[0020] Figure 2 A three-dimensional view of the integrated time domain and frequency domain equalized ultra-wideband electro-optical modulator according to the embodiment of the present application is schematically shown;

[0021] Figure 3 A flowchart of the preparation method according to the embodiment of the present application is schematically shown.

[0022] REFERENCE SIGNS:

[0023] 1 - base modulation region;

[0024] 2 - forward modulation region;

[0025] 3 - velocity mismatch region;

[0026] 4 - reverse modulation region;

[0027] 5 - first coplanar traveling wave electrode;

[0028] 6 - Lead zirconate titanate thin film waveguide;

[0029] 7 - Silicon nitride waveguide;

[0030] 8 - Second coplanar traveling wave electrode. DETAILED DESCRIPTION

[0031] Hereinafter, embodiments of the present application will be described with reference to the accompanying drawings. It should be understood, however, that the description which follows is merely illustrative and is not intended to limit the scope of the present application. In the following detailed description of embodiments of the present application, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that one or more embodiments of the present application can be practiced without these specific details. In other instances, well-known structures and functions have not been described in detail in order to avoid obscuring aspects of the present application.

[0032] The terms used herein are merely used to describe specific embodiments and are not intended to limit the present application. The terms "include" and "have" and the like used herein indicate the presence of the described features, steps, operations, and / or components but do not preclude the presence or addition of one or more other features, steps, operations, or components.

[0033] All terms used herein, including technical and scientific terms, have the same meanings as those generally understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having meanings consistent with the context of the present description, and should not be interpreted in an idealized or overly formal way.

[0034] In the case of using expressions similar to "at least one of A, B, and C, etc.", it should generally be interpreted to include any of the possibilities of one, two, or all of the items enumerated, unless otherwise specifically limited. For example, "a system having at least one of A, B, and C" should be interpreted to include a system having A alone, a system having B alone, a system having C alone, a system having both A and B, a system having both A and C, a system having both B and C, and / or a system having A, B, and C, etc.

[0035] The embodiment of the application provides an ultra-wideband electro-optical modulator integrating time domain and frequency domain equalization, which comprises a silicon substrate, a silicon dioxide buried layer, a silicon nitride waveguide 7, a lead zirconate titanate thin film waveguide 6, a first coplanar waveguide electrode 5 layer, a second coplanar waveguide electrode 8 layer and a silicon dioxide embedding layer from bottom to top. The silicon dioxide buried layer is formed on the silicon substrate; the silicon nitride waveguide 7 is formed on the silicon dioxide buried layer; the lead zirconate titanate thin film waveguide 6 constitutes two parallel arms of a Mach-Zehnder interferometer, a first section of the two parallel arms is positively polarized, a second section is negatively polarized, and the silicon nitride waveguide 7 is arranged in a section of the first section adjacent to the second section; the first coplanar waveguide electrode 5 is arranged on the lead zirconate titanate thin film waveguide 6; the second coplanar waveguide electrode 8 is arranged on the second section downstream of the lead zirconate titanate thin film waveguide 6; and the silicon dioxide embedding layer covers the first coplanar waveguide electrode 5 and the second coplanar waveguide electrode 8.

[0036] The first coplanar waveguide electrode is used for transmitting a microwave signal; the microwave signal is used for positively phase modulating an optical signal in a positively polarized section of the lead zirconate titanate thin film waveguide and negatively phase modulating the optical signal in a negatively polarized section of the lead zirconate titanate thin film waveguide; the silicon nitride waveguide is coupled with evanescent waves of the lead zirconate titanate thin film waveguide and is used for introducing a controlled time domain delay between the microwave signal and the optical signal after the positive phase modulation; and when the negative phase modulation is performed, the time domain delay is used for compensating for high-frequency modulation response attenuation of the optical signal caused by microwave loss difference of the positive phase modulation and the negative phase modulation, so that joint equalization of the time domain and the frequency domain is realized to expand a modulation bandwidth.

[0037] In the embodiment of the application, polarization of the lead zirconate titanate thin film waveguide 6 is realized by the first coplanar waveguide electrode 5 and the second coplanar waveguide electrode 8. Before the ultra-wideband electro-optical modulator is enabled, the first coplanar waveguide electrode 5 is used for applying a positive voltage to the lead zirconate titanate thin film waveguide 6 to perform positive polarization, and the second coplanar waveguide electrode 8 is used for applying a negative voltage to the second section of the lead zirconate titanate thin film waveguide 6 to perform negative polarization before the ultra-wideband electro-optical modulator is enabled.

[0038] Referring to Figure 1 and Figure 2The integrated time and frequency domain equalization ultra-wideband electro-optical modulator provided in the application can be divided into a basic modulation region 1, a forward modulation region 2, a velocity mismatch region 3 and a reverse modulation region 4. The basic modulation region 1, the forward modulation region 2 and the velocity mismatch region 3 are located in the first section of the lead zirconate titanate thin film waveguide, and the reverse modulation region 4 is located in the second section of the lead zirconate titanate thin film waveguide. The basic modulation region 1 is used to realize primary phase modulation of the optical signal; the velocity mismatch region 3 is used to introduce a controlled velocity mismatch between the microwave signal and the optical signal to realize time domain delay; and the forward modulation region 2 and the reverse modulation region 4 are used to realize phase modulation and reverse phase compensation respectively, so as to realize joint equalization of the time domain and the frequency domain under high frequency conditions, thereby expanding the device bandwidth and improving the frequency response characteristics. It should be noted that the basic modulation region 1 and the forward modulation region 2 are the same continuous region in the physical space, and the modulation effects on the optical signal are also consistent. The application divides the regions in the application actually represents the functional division of the modulator. On the one hand, the modulator can realize the basic phase modulation function as described for the basic modulation region 1, and on the other hand, the modulator can realize joint equalization of the time domain and the frequency domain based on the synergistic effect of the forward modulation region 2, the velocity mismatch region 3 and the reverse modulation region 4 to expand the modulation bandwidth. Figure 1

[0039] In the embodiment of the application, the forward modulation region 2 and the reverse modulation region 4 are secondarily polarized to realize opposite polarity through two layers of metal electrodes (the first coplanar wave electrode 5 and the second coplanar wave electrode 8). After polarization in the first coplanar wave electrode 5, opposite voltage is applied to the second coplanar wave electrode 8 for polarization, and reverse polarization effect is obtained in the reverse region of the modulator. The length of the forward modulation region 2 and the reverse modulation region 4 can be set to 500-1000 microns. When the electrode microwave loss of the reverse modulation region 4 is higher than that of the forward modulation region 2 under high frequency, the system realizes phase compensation at the frequency domain end through reverse phase modulation, so that the overall response of the modulator remains balanced in the high frequency range, thereby effectively expanding the modulation bandwidth.

[0040] The application introduces an equalization mechanism to solve the performance attenuation problem of the modulator under high frequency. It should be understood that the "high frequency" mentioned in the application is not an absolute numerical limit, but refers to the frequency band in which the modulation depth of the traditional modulator begins to decrease significantly due to factors such as microwave loss and velocity mismatch. The equalization effect can be effectively produced by the phase compensation mechanism of the reverse modulation region 4.

[0041] In the embodiment of the application, the two parallel arms are single-mode optical waveguide structures to realize low-loss optical propagation and stable mode confinement.

[0042] In the embodiment of the application, the material of the lead zirconate titanate thin film waveguide 6 can be lead zirconate titanate or lanthanum-doped lead zirconate titanate to improve the ferroelectric stability and enhance the electro-optic coefficient, thereby enhancing the modulation depth. ​

[0043] In the embodiments of the present application, the first coplanar waveguide electrode 5 and the second coplanar waveguide electrode 8 can be made of gold, silver, aluminum or copper. The geometric size and spacing of the electrodes are optimized to match to ensure efficient transmission of high-frequency electrical signals and low reflection characteristics.

[0044] In the embodiments of the present application, the lead zirconate titanate thin film waveguide 6 and the silicon nitride waveguide 7 below it exchange optical power through evanescent wave coupling. The velocity mismatch region 3 sets a specific coupling length and coupling spacing between the lead zirconate titanate thin film waveguide 6 and the silicon nitride waveguide 7, and adjusts the length of the silicon nitride waveguide to produce a controllable group velocity mismatch, so that the microwave and optical waves form a time delay in the propagation process through the evanescent wave coupling structure.

[0045] In addition, the geometric size of the first coplanar waveguide electrode 5 and the second coplanar waveguide electrode 8 is optimized to match the impedance of the external microwave transmission line. This impedance matching design can minimize microwave signal reflection during input and transmission, ensuring efficient feeding and acting of high-frequency electrical signals on the optical waveguide, which is a key guarantee for achieving ultra-wideband modulation performance.

[0046] The present application also provides a preparation method for preparing an integrated time-domain and frequency-domain equalized ultra-wideband electro-optical modulator. The flowchart of the method is shown in Figure 3 .

[0047] As shown in Figure 3 , the preparation method for preparing an integrated time-domain and frequency-domain equalized ultra-wideband electro-optical modulator includes the following steps.

[0048] First, a silicon dioxide buried oxide layer (SiO2) is formed on a silicon substrate (Si) by thermal oxidation.

[0049] Second, a silicon nitride waveguide layer (SiN) is deposited on the silicon dioxide buried oxide layer by plasma-enhanced chemical vapor deposition or low-pressure chemical vapor deposition, and is patterned by photolithography and etching process to form a silicon nitride waveguide 7.

[0050] In the embodiments of the present application, the silicon nitride waveguide layer is deposited by plasma-enhanced chemical vapor deposition or low-pressure chemical vapor deposition process, with a deposition temperature of about 300-800°C and a thickness range of 300-500 nm; it is defined as a single-mode waveguide structure by photolithography and dry etching process to realize low-loss optical propagation and stable mode confinement.

[0051] Third, a silicon dioxide isolation layer is deposited on the silicon nitride waveguide 7 before depositing the lead zirconate titanate thin film waveguide 6 (PZT) to regulate the optical electric field distribution.

[0052] In the fourth step, a lead zirconate titanate film is locally deposited and patterned on the preset section of the two parallel arms by sol-gel or magnetron sputtering, and a ferroelectric crystal structure is obtained after high-temperature annealing, and a lead zirconate titanate film waveguide 6 including the two parallel arms is formed by photolithography and etching.

[0053] In the sol-gel process, the organic metal precursors of lead, zirconium and titanium are dissolved and uniformly stirred to form a precursor solution, which is then deposited by spin coating and annealed at 600-700°C to crystallize to obtain a perovskite structure with ferroelectricity; in the magnetron sputtering process, a lead zirconate titanate film waveguide 6 ceramic target is used to deposit a thin film in an oxygen / argon mixed atmosphere, and the deposited thin film is annealed to improve the crystallinity and electro-optic response performance.

[0054] When depositing the lead zirconate titanate film, lanthanide elements can be added to form a lanthanum-doped lead zirconate titanate film to improve the ferroelectric stability and enhance the electro-optic coefficient, thereby enhancing the modulation depth.

[0055] In the fifth step, a first metal layer is deposited and patterned on the lead zirconate titanate film waveguide 6 to form a first coplanar waveguide electrode 5.

[0056] In the sixth step, a second metal layer is deposited and patterned downstream of the lead zirconate titanate film waveguide 6 to form a second coplanar waveguide electrode 8.

[0057] The first metal layer and the second metal layer are formed by photolithography and metal deposition process using gold, silver, aluminum or copper material. Figure 3 In the embodiment shown, the metal material is aluminum (Al). In the design of the waveguide electrode, an electron beam evaporation or sputtering deposition is used to deposit a metal film with a thickness of about 1 μm, and then photolithography and ion beam etching are used to form a coplanar waveguide structure with a characteristic impedance of 50 Ω. The geometric size and spacing of the electrode are optimized and matched to ensure efficient transmission of high-frequency electrical signals and low reflection characteristics.

[0058] In the seventh step, a silicon dioxide embedding layer is deposited on the substrate with the first coplanar waveguide electrode 5 and the second coplanar waveguide electrode 8 by chemical vapor deposition.

[0059] Thus, by integrating the time-domain and frequency-domain equalization structure in the lead zirconate titanate film modulator, high-speed, wideband and low-loss optical signal modulation characteristics are achieved. The structure is compatible with the silicon optical platform and can be widely used in the field of optical communication and high-speed optical signal processing.

[0060] Based on the above technical solutions, the integrated time-domain and frequency-domain equalization ultra-wideband electro-optic modulator of the present application requires equalization at the driving circuit or system end, while the present application integrates the equalization function in the modulator itself, reducing the complexity of the peripheral circuit, reducing the signal path length, and reducing reflection and distortion.

[0061] The integrated time-domain and frequency-domain equalization ultra-wideband electro-optical modulator of the application has a structure compatible with mainstream silicon optical technology, and can be implemented on a Si-based photonic chip for large-scale integration. The lead zirconate titanate thin film can be deposited by sol-gel and sputtering process, and has controllable thickness and good crystal orientation.

[0062] The integrated time-domain and frequency-domain equalization ultra-wideband electro-optical modulator of the application can significantly widen the modulation bandwidth. Through the coupling of the velocity mismatch region 3 and the reverse modulation region 4, the phase compensation of the optical field at high frequency is realized, thereby overcoming the bandwidth limitation of the traditional traveling wave electrode modulator. The 3 dB bandwidth can be effectively improved, and the traditional speed limit can be broken through.

[0063] The above describes the embodiments of the application. However, these embodiments are only for illustrative purposes, and are not intended to limit the scope of the application. Although each embodiment is described above, this does not mean that the measures in each embodiment cannot be used advantageously in combination. Those skilled in the art can make various substitutions and modifications without departing from the scope of the application, and these substitutions and modifications shall fall within the scope of the application.

Claims

1. An ultrawideband electro-optic modulator integrating time-domain and frequency-domain equalization, characterized in that, From bottom to top, it includes: silicon substrate, silicon dioxide buried oxide layer, silicon nitride waveguide, lead zirconate titanate thin film waveguide and silicon dioxide cladding layer; The lead zirconate titanate thin film waveguide forms two parallel arms. The first section of the two parallel arms is positively polarized, and the second section is negatively polarized. The silicon nitride waveguide is disposed in the section of the first section that connects with the second section. It also includes a first coplanar traveling wave electrode and a second coplanar traveling wave electrode. A first metal layer is deposited and patterned on the lead zirconate titanate thin film waveguide to form the first coplanar traveling wave electrode; a second metal layer is deposited and patterned downstream of the lead zirconate titanate thin film waveguide to form the second coplanar traveling wave electrode; and the silicon dioxide embedded layer is deposited on the substrate on which the first coplanar traveling wave electrode and the second coplanar traveling wave electrode are formed. Before the ultra-wideband electro-optic modulator is activated, a positive voltage is applied to the lead zirconate titanate thin film waveguide through the first coplanar traveling wave electrode to perform positive polarization; a reverse voltage is applied to the second section through the second coplanar traveling wave electrode to perform reverse polarization, so that the first section is kept positively polarized while the second section is reversely polarized. When the ultra-wideband electro-optic modulator is activated, the first coplanar traveling wave electrode is used to transmit microwave signals; the microwave signals are used to perform forward phase modulation of the optical signal in the first segment and reverse phase modulation of the optical signal in the second segment. The silicon nitride waveguide is evanescently coupled to the lead zirconate titanate thin film waveguide to introduce a controlled time-domain delay between the microwave signal and the optical signal after forward phase modulation. During reverse phase modulation, the time-domain delay is used to compensate for the high-frequency modulation response attenuation caused by the difference in microwave loss between forward and reverse phase modulation of the optical signal, ultimately achieving joint equalization in the time and frequency domains to expand the modulation bandwidth.

2. The ultra-wideband electro-optic modulator according to claim 1, characterized in that, The two parallel arms are single-mode optical waveguide structures.

3. The ultra-wideband electro-optic modulator according to claim 1, characterized in that, The material of the lead zirconate titanate thin film waveguide is lead zirconate titanate or lanthanum-doped lead zirconate titanate.

4. The ultra-wideband electro-optic modulator according to claim 1, characterized in that, The first coplanar traveling wave electrode and the second coplanar traveling wave electrode are impedance matched with the external microwave transmission line.

5. A fabrication method, applied to the ultra-wideband electro-optic modulator with integrated time-domain and frequency-domain equalization as described in any one of claims 1-4, characterized in that, include: A buried oxide layer of silicon dioxide is formed on a silicon substrate; A silicon nitride waveguide layer is deposited on the buried oxide layer of silicon dioxide, and patterned by photolithography and etching processes to form a silicon nitride waveguide; A lead zirconate titanate thin film is locally deposited and patterned on the predetermined section of the two parallel arms to form a lead zirconate titanate thin film waveguide including two parallel arms. A first metal layer is deposited and patterned on the lead zirconate titanate thin film waveguide to form a first coplanar traveling wave electrode. A second metal layer is deposited and patterned downstream of the lead zirconate titanate thin film waveguide to form a second coplanar traveling wave electrode. A silicon dioxide embedded layer is deposited on a substrate on which the first coplanar traveling wave electrode and the second coplanar traveling wave electrode are formed.

6. The preparation method according to claim 5, characterized in that, The step of depositing the lead zirconate titanate film further includes doping the lead zirconate titanate film with lanthanides to form a lanthanum-doped lead zirconate titanate film.

7. The preparation method according to claim 5, characterized in that, In the step of forming the two parallel arms, the two parallel arms are fabricated into a single-mode optical waveguide structure by controlling the photolithography and etching processes.

8. The preparation method according to claim 5, characterized in that, The method further includes: Before depositing the lead zirconate titanate thin film waveguide, a silicon dioxide isolation layer is deposited on the silicon nitride waveguide layer.

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