CN112764246B

CN112764246B - Thin-film lithium niobate electro-optical modulator and preparation method thereof

Info

Publication number: CN112764246B
Application number: CN202110111328.0A
Authority: CN
Inventors: 刘柳; 陈耿鑫; 阮子良; 薛煜
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2021-01-27
Filing date: 2021-01-27
Publication date: 2022-07-19
Anticipated expiration: 2041-01-27
Also published as: CN112764246A

Abstract

The invention discloses a thin-film lithium niobate electro-optic modulator and a preparation method thereof. The optical waveguide device comprises a substrate, an oxygen buried layer, a polymer layer and an optical waveguide layer which are sequentially arranged from bottom to top, a metal signal electrode and a metal grounding electrode are arranged on the optical waveguide layer or in the polymer layer below the optical waveguide layer, a 1 x 2 beam splitter, a Mach-Zehnder modulator and a 2 x 1 beam combiner are arranged on the upper bottom surface of the optical waveguide layer, the 1 x 2 beam splitter and the 2 x 1 beam combiner are positioned on two sides of the Mach-Zehnder modulator, and two output ends of the 1 x 2 beam splitter are connected through two input ends of the Mach-Zehnder modulator and the 2 x 1 beam combiner. The invention avoids microwave loss caused by a substrate in the process, reduces the process difficulty, improves the modulation efficiency, realizes super-large bandwidth and low loss, and realizes a compact and ultrahigh-performance electro-optical modulator.

Description

Thin-film lithium niobate electro-optical modulator and preparation method thereof

Technical Field

The invention relates to an electro-optical modulator and a preparation method thereof in the technical field of optical communication, optical interconnection and optical sensing, in particular to a thin-film lithium niobate electro-optical modulator based on an alumina substrate and a preparation method thereof.

Background

In the era of rapid development of informatization, continuous development of novel informatization technologies such as cloud computing, 5G and big data promotes strong demands of people on data processing and transmission technologies with high speed, low power consumption and large capacity. Integrated optics is gaining increasing favor in the fields of optical interconnection, optical communication and optical sensing by virtue of its advantages of small size, low power consumption, large bandwidth, etc. Especially, the silicon-based optoelectronics is compatible with the CMOS process in the integrated circuit, so that the hybrid integration of the optical integrated chip and the electrical integrated chip becomes possible, and the bottlenecks of electrical interconnection in the aspects of bandwidth, power consumption and the like can be greatly broken through between chips and in the chip by adopting the optical interconnection technology.

The advantages of high integration level, low cost and excellent performance of the current silicon-based photoelectronic technology taking silicon as a material are exerted in the passive aspect, but in the active aspect, the realization of higher performance is difficult due to the physical limitation of the silicon material per se. For example, silicon itself is an indirect bandgap material, and thus cannot directly emit light, and is difficult to use as a light source; the electro-optic and thermo-optic effects of silicon are very weak, so that external doping is needed to realize a good modulation function; the absorption cutoff wavelength of silicon is about 1.1um, and therefore, silicon cannot be used for optical detection of near-infrared communication bands, and other materials such as germanium need to be epitaxially grown to realize effective optical detection. Based on the above existing physical bottlenecks, better materials are sought to achieve more excellent performance.

The electro-optical modulator based on lithium niobate material is one of the modulators with the most excellent performance so far, because lithium niobate has a very large electro-optical coefficient, the modulation speed can be in ns order, and the modulation with large bandwidth can be realized under the CMOS driving voltage. The traditional lithium niobate blocky waveguide is prepared by a titanium diffusion or ion exchange mode, and the distance between an electrode and the waveguide is large due to uneven diffusion and large cross section size, so that the electro-optic modulation efficiency is very low. In recent years, with the continuous improvement of lithium niobate technology, thin-film lithium niobate is proposed and highly efficient electro-optical modulation is well achieved, but there are still some places to be improved: 1. how to realize the efficient matching of the refractive index of the optical wave group and the refractive index of the microwave group is because the refractive index of the microwave group (28) is greatly different from the refractive index of the optical wave group (4) in the conventional lithium niobate modulator. In order to overcome the difference, a silicon dioxide covering can be applied to the thin-film lithium niobate modulator to realize better group refractive index matching, but extra charges can be introduced by a plasma enhanced chemical vapor deposition method for depositing silicon dioxide, so that unnecessary carrier distribution is formed on a substrate (such as silicon and lithium niobate), the loss of the modulator is improved, and the bandwidth of the modulator is reduced. 2. Since the thin film lithium niobate is difficult to etch, an etching inclination angle naturally exists, and a high process requirement is required for depositing silicon dioxide on the thin film lithium niobate due to the existence of the inclination angle.

Disclosure of Invention

In order to solve the problems in the background art, the invention provides a thin-film lithium niobate electro-optical modulator based on an alumina substrate and a preparation method thereof, which effectively solve the problems of high requirements and difficulty of the preparation process, high loss, large driving voltage and small bandwidth of the prepared thin-film lithium niobate modulator.

The technical scheme adopted by the invention is as follows:

a thin-film lithium niobate electro-optical modulator:

the optical waveguide device comprises a substrate, an oxygen burying layer, a polymer layer and an optical waveguide layer which are sequentially arranged from bottom to top, wherein a metal signal electrode and a metal grounding electrode are arranged on the optical waveguide layer or in the polymer layer below the optical waveguide layer, a 1X 2 beam splitter, a Mach-Zehnder modulator and a 2X 1 beam combiner are arranged on the upper bottom surface of the optical waveguide layer, the 1X 2 beam splitter and the 2X 1 beam combiner are positioned on two sides of the Mach-Zehnder modulator, and two output ends of the 1X 2 beam splitter are connected through two input ends of the Mach-Zehnder modulator and the 2X 1 beam combiner.

The upper bottom surface of the optical waveguide layer is provided with a bulge, and different parts of the bulge form a 1 x 2 beam splitter, a Mach-Zehnder modulator and a 2 x 1 beam combiner.

The optical waveguide device comprises a metal signal electrode and two metal grounding electrodes, wherein the metal signal electrode is positioned in the middle of an optical waveguide layer, and the two metal grounding electrodes are positioned on two sides of the metal signal electrode.

The two waveguide arms of the Mach-Zehnder modulator are respectively positioned between two metal grounding electrodes and one metal signal electrode.

The substrate is alumina [ which may be sapphire or ruby or a material whose basic component is alumina ].

The buried oxide layer is made of silicon dioxide and is 0.1-6um thick.

The polymer layer is made of benzocyclobutene, polymethyl methacrylate and polydimethylsiloxane, and the thickness of the polymer layer is 0.1-2 um.

The optical waveguide is thin film lithium niobate, the inclination angle of the waveguide of the thin film lithium niobate is 60-70 degrees, the total thickness is 200-600nm, and the etching thickness is 100-300 nm.

The metal signal electrode and the metal grounding electrode are in a coplanar traveling wave distributed electrode structure. Therein for teaching

Second, a first method for manufacturing a thin-film lithium niobate electro-optic modulator [ on an optical waveguide layer ] includes the steps of:

step 1, sputtering to form a layer of alumina substrate;

step 2, depositing a buried oxide layer on the [ alumina ] substrate;

step 3, depositing a polymer layer with a low refractive index on the oxygen burying layer;

the preparation method is characterized by further comprising the following steps:

step 4, arranging a buried oxide layer on the upper surface of the silicon substrate, preparing a thin film lithium niobate optical waveguide layer on the buried oxide layer on the upper surface of the silicon substrate by utilizing photoetching and etching, and preparing bulges positioned in different areas of the upper surface to form a 1 x 2 beam splitter, a Mach-Zehnder modulator and a 2 x 1 beam combiner in the process of preparing the thin film lithium niobate optical waveguide layer;

step 5, inverting and covering the structure obtained in the step 4 on the structure obtained in the step 3, and bonding the polymer layer and the thin-film lithium niobate optical waveguide layer;

step 6, grinding the silicon substrate, and removing a buried oxide layer below the silicon substrate by using hydrofluoric acid;

and 7, plating a metal signal electrode and a metal grounding electrode on the inverted thin-film lithium niobate optical waveguide layer by using methods such as photoetching, sputtering and the like.

Third, a second method for manufacturing a thin-film lithium niobate electro-optical modulator, [ for disposing a metal signal electrode and a metal ground electrode in a polymer layer below an optical waveguide layer ], includes the steps of:

step 1, sputtering to form a layer of alumina substrate;

step 2, depositing an oxygen burying layer on the [ alumina ] substrate;

step 5, plating a metal signal electrode and a metal grounding electrode on the upper surface of the structure obtained in the step 4 by using methods such as photoetching, sputtering and the like;

step 6, inverting and covering the structure obtained in the step 5 on the structure obtained in the step 3, and bonding the polymer layer and the thin-film lithium niobate optical waveguide layer;

and 6, grinding the silicon substrate, and removing a buried oxide layer below the silicon substrate by using hydrofluoric acid.

In the method for preparing the thin-film lithium niobate electro-optic modulator with the improved structure, metal plating is firstly carried out and then bonding treatment is carried out, and the rest steps are similar. Therein for teaching

The method for lithography comprises a step lithography machine, a contact lithography machine, electron beam direct writing and laser direct writing.

The etching method comprises dry etching and wet etching.

The sputtering method comprises magnetron sputtering, electron beam evaporation and electroplating. "C (B)

The invention is based on the bottleneck of the thin-film lithium niobate electro-optical modulator, and innovatively adopts the thin-film lithium niobate electro-optical modulator based on the alumina substrate. The adoption of the insulating alumina substrate with a large dielectric constant can avoid the situation that silicon dioxide is deposited on the thin-film lithium niobate waveguide, and can also realize high-efficiency group refractive index matching, avoid the additional loss attached to the deposited silicon dioxide, and simultaneously can avoid the operation of depositing the silicon dioxide on the thin-film lithium niobate for refractive index matching by using the structure, thereby further reducing the process difficulty.

The invention can further improve the performance of the device, adopts the mode of plating metal and bonding, improves the overlap integral between the microwave field and the light wave field, and effectively reduces the half-wave voltage, thereby realizing the novel thin-film lithium niobate electro-optical modulator with ultra-large bandwidth, low loss and low driving voltage.

The technical effects produced by the invention are as follows:

(1) in the invention, the step of depositing the silicon dioxide cover to realize group refractive index matching is removed by adopting an alumina substrate structure, and compared with the traditional thin-film lithium niobate modulator, the microwave loss caused by the substrate when the silicon dioxide cover is deposited is avoided, and the loss of the modulator is further reduced, as shown in figure 13.

(2) The invention avoids directly depositing silicon dioxide on the thin film lithium niobate with an inclination angle by changing the structure of the thin film lithium niobate, thereby reducing the process difficulty.

(3) Compared with other oxides such as silicon dioxide and the like, the aluminum oxide substrate structure is utilized, the heat dissipation performance is better, so that the influence on the bandwidth caused by temperature can be reduced in the process of preparation, and the bandwidth of the modulator is further increased compared with the traditional thin-film lithium niobate modulator, as shown in the attached figure 12.

(4) The invention adopts the alumina substrate, the oxide is easy to prepare and has low price, and the preparation cost of the device can be reduced.

(5) The invention ensures that the electron beam exposure etching can be carried out on the thin film lithium niobate waveguide on the high-refractive-index substrate silicon, and ensures the low-loss advantage of the etched thin film lithium niobate waveguide, as shown in figure 13.

(6) The basic structure of the invention is improved, and the overlapping area of the light wave field and the microwave field in the electro-optical modulation process is further increased, so that the novel thin-film lithium niobate electro-optical modulator with ultra-large bandwidth can be realized.

Drawings

The following is a brief description of what is presented in the drawings of the specification:

FIG. 1 is a flow chart for the fabrication of a thin film lithium niobate electro-optical modulator of the basic structure of the present invention.

Fig. 2 is a flow chart of the fabrication of the thin film lithium niobate electro-optic modulator with the improved structure of the present invention.

FIG. 3 is a transverse cross-sectional view of the structure obtained in step 1 of the production method of the present invention.

FIG. 4 is a transverse cross-sectional view of the structure obtained in step 2 of the manufacturing method of the present invention.

FIG. 5 is a transverse cross-sectional view of the structure obtained in step 3 of the manufacturing method of the present invention.

FIG. 6 is a transverse cross-sectional view of the structure obtained in step 4 of the manufacturing method of the present invention.

FIG. 7 is a transverse cross-sectional view of the structure resulting from step 5 of the manufacturing method of the present invention.

Fig. 8 is a transverse sectional view of the basic structure in the present invention.

Fig. 9 is a transverse sectional view of the improved structure in the present invention.

Fig. 10 is a three-dimensional perspective view of a thin-film lithium niobate electro-optic modulator of the basic structure of the present invention.

Fig. 11 is a graph showing the group refractive index matching between the microwave and the optical wave in the thin-film lithium niobate electro-optic modulator having the basic structure according to the present invention.

Fig. 12 is a comparison graph of the 3dB bandwidth of the basic structure, the improved structure and the conventional thin-film lithium niobate electro-optic modulator when the half-wave voltage is 4 v.

Fig. 13 is a graph showing a loss comparison between a thin-film lithium niobate electro-optical modulator of the basic structure of the present invention and a conventional thin-film lithium niobate electro-optical modulator.

In the figure, 1-substrate, 2-buried oxide layer, 3-polymer layer, 4-optical waveguide layer, 5-silicon substrate, 6-metal signal electrode, 7-metal ground electrode, 8-1 × 2 beam splitter, 9-mach-zehnder modulator, 10-2 × 1 beam combiner.

Detailed Description

The following will explain in detail specific embodiments of the present invention, such as shapes and structures of the respective members, interconnection relationships between the respective portions, functions and operation principles of the respective portions, manufacturing processes, and methods of operation and use. So as to provide a more complete, accurate and thorough understanding of the concepts and technical solutions of the present invention.

The invention is used for solving the inevitable loss influence of the conventional thin-film lithium niobate electro-optical modulator in the process, such as the influence on the performance of the modulator due to unnecessary carrier distribution caused by a substrate; such as group index mismatch due to incomplete contact of the deposited silica cap with the thin film lithium niobate waveguide, and the like. The invention is embodied in the structural innovation.

Example 1

As shown in fig. 8, the present embodiment includes a substrate 1, a buried oxide layer 2, a polymer layer 3, and an optical waveguide layer 4, which are sequentially arranged from bottom to top, where [ i.e., the buried oxide layer 2 is disposed on the substrate 1, the polymer layer 3 is disposed on the buried oxide layer 2, and the optical waveguide layer 4 is disposed on the polymer layer 3. "C (B)

Arranging a metal signal electrode 6 and a metal grounding electrode 7 on the optical waveguide layer 4, wherein the metal signal electrode 6 and the metal grounding electrode 7 are arranged on the optical waveguide layer 4; the bottom surface of the optical waveguide layer 4 is arranged to form a 1 x 2 beam splitter 8, a Mach-Zehnder modulator 9 and a 2 x 1 beam combiner 10, the 1 x 2 beam splitter 8 and the 2 x 1 beam combiner 10 are positioned at two sides of the Mach-Zehnder modulator 9, two output ends of the 1 x 2 beam splitter 8 are connected through two input ends of the Mach-Zehnder modulator 9 and the 2 x 1 beam combiner 10, an input end of the 1 x 2 beam splitter 8 is connected to an input end of an external optical fiber, and an output end of the 2 x 1 beam combiner 10 is connected to an output end of the external optical fiber. Therein for teaching

The bottom surface of the optical waveguide layer 4 is provided with a bulge, the bulge is also of the same waveguide structure as the material of the optical waveguide layer 4, and different parts of the bulge form a 1-by-2 beam splitter 8, a Mach-Zehnder modulator 9 and a 2-by-1 beam combiner 10.

In the specific implementation, the optical waveguide comprises a metal signal electrode 6 and two metal grounding electrodes 7, wherein the metal signal electrode 6 is positioned in the middle of the optical waveguide layer 4, and the two metal grounding electrodes 7 are positioned on two sides of one metal signal electrode 6. The metal signal electrode 6 and the metal grounding electrode 7 are in a coplanar traveling wave distributed electrode structure. The two waveguide arms of the mach-zehnder modulator 9 are respectively located between two metal ground electrodes 7 and one metal signal electrode 6. The direction of the connecting line between the beam splitter (8) (1 × 2) and the beam combiner (10) (2 × 1) is perpendicular to the direction of the connecting line between the two metal grounding electrodes (7). "C (B)

In specific implementation, the substrate 1 is alumina, the oxygen burying layer 2 is silicon dioxide, and the thickness is 0.8 um; the polymer layer 3 is made of benzocyclobutene, and the thickness is 0.45 um; the optical waveguide 4 is thin film lithium niobate, the inclination angle of the waveguide of the thin film lithium niobate is 60 degrees, the total thickness is 600nm, and the etching thickness is 300 nm.

As shown in fig. 1, the preparation process includes the following steps:

step 1, as shown in fig. 3, forming a layer of [ alumina ] substrate 1 by using an electron beam sputtering method;

step 2, as shown in fig. 4, depositing a buried oxide layer 2 on the [ alumina ] substrate 1 by using an electron beam sputtering method;

and 3, preparing a polymer layer 3 with a certain thickness on the oxygen burying layer 2 by glue homogenizing and baking as shown in figure 5.

Step 4, arranging a layer of buried oxide layer 2 on the upper surface of a silicon substrate 5, preparing a thin film lithium niobate optical waveguide layer 4 on the buried oxide layer 2 on the upper surface of the silicon substrate 5 by utilizing photoetching and etching, and preparing bulges positioned in different areas of the upper surface to form a 1 x 2 beam splitter 8, a Mach-Zehnder modulator 9 and a 2 x 1 beam combiner 10 in the process of preparing the thin film lithium niobate optical waveguide layer 4;

step 5, as shown in fig. 6, inverting and covering the structure obtained in step 4 on the structure obtained in step 3, and bonding the polymer layer 3 and the thin-film lithium niobate optical waveguide layer 4;

step 6, as shown in fig. 7, the silicon substrate 5 is removed by grinding and polishing, and then the buried oxide layer 2 under the silicon substrate 5 is removed by using the corrosivity of hydrofluoric acid;

step 7, as shown in fig. 8, a metal signal electrode 6 and a metal ground electrode 7 are plated on the inverted thin-film lithium niobate optical waveguide layer 4 by photolithography, sputtering, or the like.

Thus, a metal signal electrode 6 and a metal grounding electrode 7 are plated on the smooth and flat top of the thin-film lithium niobate optical waveguide layer 4 in a coplanar distributed traveling wave electrode structure to form a GSG structure, the whole structure is symmetrical left and right by taking the central line of the middle metal signal electrode as a symmetry axis, and the waveguide distance between the metal signal electrode 6 and the thin-film lithium niobate is equal to the waveguide distance between the metal grounding electrode 7 and the thin-film lithium niobate.

The structure is an innovative basic structure, and the invention further improves and adds more innovations on the basis of the basic structure to form an improved structure. The method comprises the following specific steps: "C (B)

The structure is the same as that of the modified structure finally prepared in this way, except that the metallic signal electrode 6 and the metallic ground electrode 7 are interposed between the optical waveguide layer 4 and the polymer layer below the optical waveguide layer 4. Therein for teaching

As shown in fig. 12, the bandwidth of the basic structure is improved by about 5GHz compared with the conventional thin-film lithium niobate modulator.

Example 2

As shown in fig. 9, the present embodiment includes a substrate 1, a buried oxide layer 2, a polymer layer 3, and an optical waveguide layer 4, which are arranged in this order from bottom to top [ i.e., the buried oxide layer 2 is disposed on the substrate 1, the polymer layer 3 is disposed on the buried oxide layer 2, and the optical waveguide layer 4 is disposed on the polymer layer 3. Therein for teaching

Arranging a metal signal electrode 6 and a metal ground electrode 7 in the polymer layer 3 below the optical waveguide layer 4, [ the metal signal electrode 6 and the metal ground electrode 7 are placed between the optical waveguide layer 4 and the polymer layer below the optical waveguide layer 4; the bottom surface of the optical waveguide layer 4 is arranged to form a 1 x 2 beam splitter 8, a Mach-Zehnder modulator 9 and a 2 x 1 beam combiner 10, the 1 x 2 beam splitter 8 and the 2 x 1 beam combiner 10 are positioned at two sides of the Mach-Zehnder modulator 9, two output ends of the 1 x 2 beam splitter 8 are connected through two input ends of the Mach-Zehnder modulator 9 and the 2 x 1 beam combiner 10, an input end of the 1 x 2 beam splitter 8 is connected to an input end of an external optical fiber, and an output end of the 2 x 1 beam combiner 10 is connected to an output end of the external optical fiber. Therein for teaching

The bottom surface of the optical waveguide layer 4 is provided with a bulge, the bulge is also of a waveguide structure with the same material as the material of the optical waveguide layer 4, and different parts of the bulge form a 1-x 2 beam splitter 8, a Mach-Zehnder modulator 9 and a 2-x 1 beam combiner 10.

In specific implementation, the substrate 1 is alumina, the oxygen burying layer 2 is silicon dioxide, and the thickness is 2 um; the polymer layer 3 is made of benzocyclobutene, and the thickness is 1.25 um; the optical waveguide 4 is thin film lithium niobate, the inclination angle of the thin film lithium niobate waveguide is 60 degrees, the total thickness is 600nm, and the etching thickness is 300 nm.

As shown in fig. 2, for a further improved structure of the case where the metallic signal electrode 6 and the metallic ground electrode 7 are disposed in the polymer layer 3 below the optical waveguide layer 4, the manufacturing method includes the steps of:

step 1, sputtering to form a layer of [ alumina ] substrate 1;

step 2, depositing an oxygen burying layer 2 on the [ alumina ] substrate 1;

3, depositing a polymer layer 3 with a low refractive index on the oxygen burying layer 2;

step 5, plating a metal signal electrode 6 and a metal grounding electrode 7 on the upper surface of the structure obtained in the step 4 by using methods such as photoetching, sputtering and the like;

step 6, inverting and covering the structure obtained in the step 5 on the structure obtained in the step 3, and bonding the polymer layer 3 and the thin-film lithium niobate optical waveguide layer 4;

and 6, grinding the substrate of the silicon substrate 5, and removing the buried oxide layer 2 below the silicon substrate 5 by using hydrofluoric acid.

In the method for preparing the thin-film lithium niobate electro-optic modulator with the improved structure, metal plating is firstly carried out and then bonding treatment is carried out, and the rest steps are similar. "C (B)

As shown in fig. 12, it can be seen that the improved structure of the present invention improves the bandwidth of 30GHz over the basic structure.

Compared with the improved structure and the basic structure, the improved structure can improve the overlap integral between the light wave field and the microwave field to the maximum extent, reduce the driving voltage required in the modulation process, further improve the modulation efficiency, and further improve the bandwidth.

The structure of the invention can be applied to an electro-optical modulator based on a Mach-Zehnder structure, a 1 x 2 beam splitter is utilized to split two beams of light with equal success rate, the two beams of light respectively enter two arms of the Mach-Zehnder structure, corresponding to two thin film lithium niobate waveguides of the structure, modulation electric signals are applied to the outside, the impedance matching and refractive index matching conditions are met, under the condition of low microwave loss, the modulated electric signals are loaded into optical signals, the light waves of the two arms are combined through a 2 x 1 beam combiner, and finally the light waves of different signals form different interference to realize the conversion of high-performance optical electric signals.

The conventional thin-film lithium niobate electro-optic modulator adopts a silicon dioxide covering layer to realize group refractive index matching, so that unnecessary loss is easily introduced in the process of preparation, and the process difficulty is increased. The structure adopts the alumina substrate, so that the heat dissipation performance of the device can be improved, and meanwhile, the matching of the refractive indexes can be better realized, as shown in fig. 11. Meanwhile, aiming at the basic structure provided by the invention, the overlapping integral of a light wave field and a microwave field is increased by plating metal and then bonding, so that the modulation efficiency is further improved, and the modulation bandwidth is greatly improved. As shown in fig. 12, when the half-wave voltage is 4 v, the bandwidth can be as high as 135GHz, thus realizing a very large bandwidth, low loss, low driving voltage thin film lithium niobate electro-optic modulator,

therefore, the invention can avoid the microwave loss caused by the substrate in the process and reduce the process difficulty. The structure of the modulator is further improved, the modulation efficiency can be improved, the novel thin-film lithium niobate electro-optic modulator is superior to the conventional thin-film lithium niobate electro-optic modulator provided at present, the ultra-large bandwidth, low loss and low driving voltage is realized, and the compact and ultrahigh-performance electro-optic modulator is convenient to realize in the application fields of data centers, optical interconnection and the like.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other structures, materials, thicknesses, etc., which are changed according to the structure, and any other changes, modifications, substitutions, combinations, simplifications which do not depart from the spirit and principle of the present invention, should be regarded as equivalent replacements within the protection scope of the present invention.

Claims

1. A preparation method of a thin-film lithium niobate electro-optical modulator is characterized by comprising the following steps: the method is directed to a thin-film lithium niobate electro-optical modulator, which specifically comprises a substrate (1), an oxygen buried layer (2), a polymer layer (3) and an optical waveguide layer (4) which are sequentially arranged from bottom to top, wherein a metal signal electrode (6) and a metal grounding electrode (7) are arranged in the polymer layer (3) on the optical waveguide layer (4), a 1 x 2 beam splitter (8), a Mach-Zehnder modulator (9) and a 2 x 1 beam combiner (10) are arranged on the upper bottom surface of the optical waveguide layer (4), the 1 x 2 beam splitter (8) and the 2 x 1 beam combiner (10) are positioned on two sides of the Mach-Zehnder modulator (9), and two output ends of the 1 x 2 beam splitter (8) are connected through two input ends of the Mach-Zehnder modulator (9) and the 2 x 1 beam combiner (10);

the preparation method comprises the following steps:

step 1, sputtering to form a layer of substrate (1);

step 2, depositing a buried oxide layer (2) on the substrate (1);

3, depositing a polymer layer (3) on the oxygen burying layer (2);

step 4, arranging a first buried oxide layer on the upper surface of a silicon substrate (5), preparing a thin film lithium niobate optical waveguide layer (4) on the first buried oxide layer on the upper surface of the silicon substrate (5) by utilizing photoetching and etching, and preparing bulges positioned in different areas of the upper surface to form a 1 x 2 beam splitter (8), a Mach-Zehnder modulator (9) and a 2 x 1 beam combiner (10) in the process of preparing the thin film lithium niobate optical waveguide layer (4);

step 5, inverting and covering the structure obtained in the step 4 on the structure obtained in the step 3, and bonding the polymer layer (3) and the thin-film lithium niobate optical waveguide layer (4);

step 6, grinding the silicon substrate (5), and removing a first buried oxide layer below the silicon substrate (5) by using hydrofluoric acid;

and 7, plating a metal signal electrode (6) and a metal grounding electrode (7) on the inverted thin-film lithium niobate optical waveguide layer (4) by using a photoetching and sputtering method.

2. A preparation method of a thin-film lithium niobate electro-optical modulator is characterized by comprising the following steps: the method is directed to a thin-film lithium niobate electro-optic modulator, and specifically comprises a substrate (1), a buried oxide layer (2), a polymer layer (3) and an optical waveguide layer (4) which are sequentially arranged from bottom to top, wherein a metal signal electrode (6) and a metal grounding electrode (7) are arranged in the polymer layer (3) on the optical waveguide layer (4), a 1 x 2 beam splitter (8), a Mach-Zehnder modulator (9) and a 2 x 1 beam combiner (10) are arranged on the upper bottom surface of the optical waveguide layer (4), the 1 x 2 beam splitter (8) and the 2 x 1 beam combiner (10) are positioned on two sides of the Mach-Zehnder modulator (9), and two output ends of the 1 x 2 beam splitter (8) are connected through two input ends of the Mach-Zehnder modulator (9) and the 2 x 1 beam combiner (10);

the preparation method comprises the following steps:

step 1, sputtering to form a layer of substrate (1);

step 2, depositing a buried oxide layer (2) on the substrate (1);

3, depositing a polymer layer (3) on the oxygen burying layer (2);

step 5, plating a metal signal electrode (6) and a metal grounding electrode (7) on the upper surface of the structure obtained in the step 4 by utilizing a photoetching and sputtering method;

step 6, inverting and covering the structure obtained in the step 5 on the structure obtained in the step 3, and bonding the polymer layer (3) and the thin-film lithium niobate optical waveguide layer (4);

and 7, grinding the silicon substrate (5), and removing a first buried oxide layer below the silicon substrate (5) by using hydrofluoric acid.