Heterogeneous integrated electro-optical modulator and preparation method thereof

Abstract

The embodiment of the invention provides a heterogeneous integrated electro-optical modulator and a preparation method thereof, and relates to the technical field of electro-optical integrated devices.The electro-optical modulator is characterized in that a lower cladding is located on the top surface of a first substrate; the laminated waveguide core is located on the top surface of the lower cladding, the laminated waveguide core comprises a first-layer waveguide core, a middle layer and a second-layer waveguide core, and the middle layer is arranged between the first-layer waveguide core and the second-layer waveguide core; the bonding dielectric layer covers the top surface of the laminated waveguide core; the electro-optical thin film layer is bonded on the top surface of the bonding dielectric layer, and the electro-optical thin film layer and at least one layer of waveguide core in the laminated waveguide core form a composite waveguide core; the electrodes are arranged above or below the electro-optical thin film layer, and the electrodes are located on the two sides of the laminated waveguide core on the horizontal projection. According to the scheme, the structure and application of the electro-optical modulator are more flexible, and the application range or scene of the electro-optical modulator is expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of electro-optical integrated devices, and in particular to a heterogeneously integrated electro-optical modulator and a preparation method thereof. Background Art

[0002] Photonic platforms based on silicon waveguide cores or silicon nitride waveguide cores can realize a wide range of planar integrated devices and chip-level solutions using CMOS-compatible manufacturing processes. Phase modulators are one of the core devices of photonic integrated circuits. Photonic platforms based on silicon or silicon nitride can usually use thermo-optical effects, stress-optical effects, etc. to achieve optical phase modulation. However, due to limitations in material properties such as thermal conduction speed, charging and discharging time, and device structure, these modulators are still insufficient in terms of speed, power, and modulation efficiency. An alternative is to use electro-optic modulation, but the electro-optical effect of silicon and silicon nitride is very weak, and must be combined with materials with significant electro-optical effects to achieve efficient electro-optical phase modulation. Ferroelectric materials have significant electro-optical effects, among which lithium niobate (LiNbO3) is a typical representative. It has a strong electro-optical effect (1550nm: r 33 =27pm / V), larger refractive index (1550nm: n o =2.21,n e =2.14), a wide light transmission window (400nm~5μm) and stable physical and chemical properties, making it the most competitive electro-optical material.

[0003] At present, due to the reasons that electro-optical materials are generally difficult to etch, or there are large differences in thermal expansion coefficients with silicon substrates, potential contamination problems, etc., the existing technology realizes electro-optic modulation on silicon or silicon nitride photonics platforms. Usually, a structure without etching the electro-optical material is adopted, and the electro-optical material film is heterogeneously integrated with the waveguide core of silicon or silicon nitride, that is, the electro-optical material film is bonded on the single-layer waveguide core of silicon or silicon nitride to form a silicon-electro-optical film composite waveguide or a silicon nitride-electro-optical film composite waveguide.

[0004] The existing technical solution uses a single-layer waveguide core and an electro-optical film to form a composite waveguide. Due to the single material and structure of the single-layer waveguide core, the optical chip is limited to achieve more functions. For example, the silicon waveguide core has a high refractive index and a strong ability to limit the light field, which can achieve high-density integration of photonic devices, but the loss is relatively high; the stoichiometric silicon nitride waveguide core has very low propagation loss and a wide transparent window, but the refractive index is relatively low, and the ability to limit the light field is weak, so the integration density of photonic devices is low. Summary of the invention

[0005] In view of this, an embodiment of the present invention provides a heterogeneously integrated electro-optic modulator to solve the technical problems of low structural flexibility and limited application of composite waveguide or electro-optic modulation devices in the prior art. The heterogeneously integrated electro-optic modulator includes:

[0006] A first substrate 1;

[0007] A lower cladding layer 2, wherein the lower cladding layer 2 is located on the top surface of the first substrate 1;

[0008] A laminated waveguide core 3, wherein the laminated waveguide core 3 is located on the top surface of the lower cladding layer 2, wherein the laminated waveguide core 3 comprises a first layer of waveguide core 301, an intermediate layer 302, and a second layer of waveguide core 303, wherein the intermediate layer 302 is arranged between the first layer of waveguide core 301 and the second layer of waveguide core 303;

[0009] A bonding dielectric layer 4, wherein the bonding dielectric layer 4 covers the top surface of the laminated waveguide core 3;

[0010] an electro-optical film layer 501, one side of the electro-optical film layer 501 is bonded to the top surface of the bonding medium layer 4, wherein the electro-optical film layer 501 and at least one layer of the waveguide core in the stacked waveguide core 3 form a composite waveguide core, and any one or any combination of the different refractive indexes of the electro-optical film layer 501, the different refractive indexes of the waveguide cores, the different thicknesses of the waveguide cores, the different widths of the waveguide cores, and the different thicknesses of the intermediate layers 302 enable the electro-optical film layer 501 and the waveguide cores of different layers from top to bottom in the stacked waveguide core 3 to form a composite waveguide core;

[0011] The electrode 6 is disposed above or below the electro-optical thin film layer 501 , and the electrode 6 is located on both sides of the laminated waveguide core 3 in horizontal projection.

[0012] The embodiment of the present invention also provides a method for preparing a heterogeneously integrated electro-optic modulator to solve the technical problems of low structural flexibility and limited application of composite waveguide or electro-optic modulation devices in the prior art. The method comprises:

[0013] The first substrate 1 and the lower cladding layer 2 are prepared in sequence;

[0014] The first waveguide core 301, the intermediate layer 302 and the second waveguide core 303 are sequentially formed on the top surface of the lower cladding 2 to form the laminated waveguide core 3; or, two waveguide core layers and an intermediate material layer 3022 are formed on the top surface of the lower cladding 2 at one time, the intermediate material layer 3022 is located between the two waveguide core layers, and the two waveguide core layers and the intermediate material layer 3022 are patterned to form the first waveguide core 301, the intermediate layer 302 and the second waveguide core 303 to form the laminated waveguide core 3;

[0015] forming the bonding dielectric layer 4 on the top surface of the laminated waveguide core 3;

[0016] Bonding one side of the electro-optical thin film layer 501 to the top surface of the bonding medium layer 4;

[0017] An electrode 6 is formed above or below the electro-optical thin film layer 501 .

[0018] Compared with the prior art, the beneficial effects achieved by at least one of the above technical solutions adopted in the embodiments of the present specification include at least: it is proposed to set a stacked waveguide core 3 in a heterogeneous integrated electro-optic modulator, the stacked waveguide core 3 includes a first waveguide core 301, an intermediate layer 302 and a second waveguide core 303 arranged in a stacked manner, the intermediate layer 302 is arranged between the first waveguide core 301 and the second waveguide core 303, the bonding medium layer 4 covers the top surface of the stacked waveguide core 3, so that the electro-optical thin film layer 501 bonded to the bonding medium layer 4 can form a composite waveguide core with at least one waveguide core in the stacked waveguide core 3, the refractive index of the electro-optical thin film layer 501 is different, the refractive index of the waveguide core is different, the thickness of the waveguide core is different, the width of the waveguide core is different, and the like. Any one or any combination of the different thicknesses of the intermediate layer can make the electro-optic film layer 501 and the waveguide cores of different numbers from top to bottom in the stacked waveguide core 3 form a composite waveguide core. Since the refractive index of the electro-optic film layer 501, the refractive index of the waveguide core, the thickness of the waveguide core, the width of the waveguide core and the thickness of the intermediate layer can be adjusted and set according to specific needs, the structure of the electro-optic modulator has high flexibility. In addition, due to the flexible setting of the structure of the electro-optic modulator, different numbers of waveguide cores from top to bottom in the stacked waveguide core 3 can arbitrarily form a composite waveguide core with the electro-optic film layer 501, which makes the application of the electro-optic modulator more flexible and expands the application scope or scenario of the electro-optic modulator. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 Schematic diagram of a heterogeneous integrated electro-optic modulator provided by an embodiment of the present invention Figure 1 ;

[0021] Figure 2 is a schematic diagram of a structure in which a lower cladding layer is formed on a first substrate provided by an embodiment of the present invention;

[0022] Figure 3It is a schematic diagram of a structure of forming a first waveguide core layer on a lower cladding layer provided by an embodiment of the present invention;

[0023] Figure 4 It is a structural schematic diagram of a patterned first waveguide core layer becoming a first layer of waveguide core provided by an embodiment of the present invention;

[0024] Figure 5 It is a schematic diagram of a structure in which an intermediate layer is formed to cover the first layer of waveguide core and the lower cladding provided by an embodiment of the present invention;

[0025] Figure 6 It is a schematic diagram of a structure in which a second waveguide core layer is formed on an intermediate layer, provided by an embodiment of the present invention;

[0026] Figure 7 It is a schematic structural diagram of a second waveguide core layer formed by a patterned second waveguide core layer provided by an embodiment of the present invention;

[0027] Figure 8 It is a schematic structural diagram of another patterned second waveguide core layer forming a second waveguide core provided by an embodiment of the present invention;

[0028] Fig. 9 It is a schematic diagram of a structure in which a bonding dielectric layer is formed to cover a second layer of waveguide core and an intermediate layer, provided by an embodiment of the present invention;

[0029] Fig.10 It is a schematic diagram of a structure of bonding an electro-optical material wafer on a bonding dielectric layer provided by an embodiment of the present invention;

[0030] Fig.11 It is a structural schematic diagram of a second substrate from which an electro-optical material wafer is removed provided by an embodiment of the present invention;

[0031] Fig.12 It is a schematic diagram of a structure of forming an electrode on a buried oxide layer above an electro-optical thin film layer provided by an embodiment of the present invention;

[0032] Fig.13 It is a schematic diagram of a structure in which grooves are formed in the middle layer and the lower cladding layer on both sides of a laminated waveguide core provided by an embodiment of the present invention;

[0033] Fig.14 is a schematic diagram of a structure of forming an electrode in a groove provided by an embodiment of the present invention;

[0034] Fig.15 It is a schematic diagram of a structure in which a bonding dielectric layer is formed to cover a second waveguide core, an intermediate layer, an electrode and a portion of a groove not filled by an electrode, provided by an embodiment of the present invention;

[0035] Fig.16is a schematic structural diagram of a bonded electro-optical thin film layer provided by an embodiment of the present invention;

[0036] Fig.17 It is a schematic diagram of a structure in which a lower cladding layer, a first waveguide core layer, an intermediate material layer and a second waveguide core layer are sequentially formed on a first substrate, provided by an embodiment of the present invention;

[0037] Fig.18 It is a schematic structural diagram of a laminated waveguide core formed by a patterned second waveguide core layer, an intermediate material layer and a first waveguide core layer provided by an embodiment of the present invention;

[0038] Fig.19 It is a schematic diagram of a structure of forming a bonding dielectric layer covering a laminated waveguide core and an intermediate layer provided by an embodiment of the present invention;

[0039] Fig. 20 It is a schematic structural diagram of a second waveguide core layer formed by a patterned second waveguide core layer provided by an embodiment of the present invention;

[0040] Fig.21 It is a structural schematic diagram of a patterned intermediate material layer and a first waveguide core layer forming a first waveguide core and an intermediate layer provided by an embodiment of the present invention;

[0041] Fig. 22 It is a schematic diagram of a structure in which a bonding dielectric layer is formed to cover a second waveguide core, an intermediate layer and a lower cladding layer, provided by an embodiment of the present invention;

[0042] Fig.23 Schematic diagram of a heterogeneous integrated electro-optic modulator provided by an embodiment of the present invention Figure 2 ;

[0043] Fig.24 It is a flow chart of a method for preparing a heterogeneously integrated electro-optic modulator provided in an embodiment of the present invention.

[0044] Reference numerals in the figures:

[0045] 1. First substrate; 2. Lower cladding; 3. Laminated waveguide core; 4. Bonding dielectric layer; 5. Electro-optic material wafer; 6. Electrode; 7. Groove; 301. First waveguide core; 3011. First waveguide core layer; 302. Middle layer; 3021. Middle layer segment; 3022. Middle material layer; 303. Second waveguide core; 3031. Second waveguide core layer; 401. Dielectric layer segment; 501. Electro-optic thin film layer; 502. Buried oxide layer; 503. Second substrate. DETAILED DESCRIPTION

[0046] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0047] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0048] In an embodiment of the present invention, a heterogeneously integrated electro-optic modulator is provided, such as Figure 1 As shown, the heterogeneously integrated electro-optic modulator includes from bottom to top:

[0049] A first substrate 1;

[0050] A lower cladding layer 2, wherein the lower cladding layer 2 is located on the top surface of the first substrate 1;

[0051] A laminated waveguide core 3, wherein the laminated waveguide core 3 is located on the top surface of the lower cladding layer 2, wherein the laminated waveguide core 3 comprises a first layer of waveguide core 301, an intermediate layer 302, and a second layer of waveguide core 303, wherein the intermediate layer 302 is arranged between the first layer of waveguide core 301 and the second layer of waveguide core 303;

[0052] A bonding dielectric layer 4, wherein the bonding dielectric layer 4 covers the top surface of the laminated waveguide core 3;

[0053] an electro-optical film layer 501, one side of the electro-optical film layer 501 is bonded to the top surface of the bonding medium layer 4, wherein the electro-optical film layer 501 and at least one layer of the waveguide core in the stacked waveguide core 3 form a composite waveguide core, and any one or any combination of the different refractive indexes of the electro-optical film layer 501, the different refractive indexes of the waveguide cores, the different thicknesses of the waveguide cores, the different widths of the waveguide cores, and the different thicknesses of the intermediate layers makes the electro-optical film layer 501 and the waveguide cores of different layers from top to bottom in the stacked waveguide core 3 form a composite waveguide core;

[0054] The electrode 6 is disposed above or below the electro-optical thin film layer 501 , and the electrode 6 is located on both sides of the laminated waveguide core 3 in horizontal projection.

[0055] Depend on Figure 1As shown, in the embodiment of the present invention, it is proposed to set a stacked waveguide core 3 in a heterogeneously integrated electro-optic modulator, and the stacked waveguide core 3 includes a first waveguide core 301, an intermediate layer 302, and a second waveguide core 303 that are stacked, and the intermediate layer 302 is arranged between the first waveguide core 301 and the second waveguide core 303, and the bonding medium layer 4 covers the top surface of the stacked waveguide core 3, so that the electro-optical thin film layer 501 bonded to the bonding medium layer 4 can form a composite waveguide core with at least one waveguide core in the stacked waveguide core 3, and any of the refractive index of the electro-optical thin film layer 501 is different, the refractive index of the waveguide core is different, the thickness of the waveguide core is different, the width of the waveguide core is different, and the thickness of the intermediate layer is different. Any one or any combination of the above mentioned items can make the electro-optic film layer 501 and the waveguide cores of different numbers from top to bottom in the stacked waveguide core 3 form a composite waveguide core. Since any one or any combination of the refractive index of the electro-optic film layer 501, the refractive index of the waveguide core, the thickness of the waveguide core, the width of the waveguide core and the thickness of the intermediate layer can be adjusted and set according to specific needs, the structure of the electro-optic modulator has high flexibility. In addition, due to the flexible setting of the structure of the electro-optic modulator, different numbers of waveguide cores from top to bottom in the stacked waveguide core 3 can arbitrarily form a composite waveguide core with the electro-optic film layer 501, which makes the application of the electro-optic modulator more flexible and expands the application scope or scenario of the electro-optic modulator.

[0056] In specific implementation, in order to further improve the flexibility of the structure, setting and application of the heterogeneously integrated electro-optical modulator, it is proposed that the materials of the first waveguide core 301 and the second waveguide core 303 can be the same or different, but the refractive index of the first waveguide core 301 and the second waveguide core 303 are required to be respectively greater than the refractive index of the lower cladding 2 and the refractive index of the intermediate layer 302.

[0057] Specifically, the material of the first waveguide core 301 can be any one of stoichiometric silicon nitride, silicon-rich silicon nitride, silicon and the like, and the material of the second waveguide core 303 can be any one of stoichiometric silicon nitride, silicon-rich silicon nitride, silicon and the like.

[0058] In a specific implementation, in order to further improve the flexibility of the structure, setting and application of the heterogeneous integrated electro-optic modulator, it is proposed that the widths of the first layer waveguide core 301 and the second layer waveguide core 303 may be the same or different, for example, Figure 1 As shown, the widths of the first layer waveguide core 301 and the second layer waveguide core 303 are the same; the widths of the first layer waveguide core 301 and the second layer waveguide core 303 are different, as shown in FIG. Figure 7As shown, the width of the first layer waveguide core 301 may be smaller than the width of the second layer waveguide core 303. Fig.21 As shown, the width of the first layer of waveguide core 301 may be greater than the width of the second layer of waveguide core 303. Regardless of whether the widths of the first layer of waveguide core 301 and the second layer of waveguide core 303 are the same, the first layer of waveguide core 301 and the second layer of waveguide core 303 need to overlap in horizontal projection, and the overlap includes complete overlap and partial overlap.

[0059] Specifically, the complete overlap means that the second layer of waveguide cores 303 are completely located within the first layer of waveguide cores 301 in horizontal projection (e.g. Figure 1 As shown, at this time, the width of the first layer waveguide core 301 is equal to the width of the second layer waveguide core 303. Fig.21 As shown, at this time, the width of the first layer waveguide core 301 is greater than the width of the second layer waveguide core 303, and the second layer waveguide core 303 is located directly above the first layer waveguide core 301), or, in horizontal projection, the second layer waveguide core 303 completely covers the first layer waveguide core 301 (that is, the first layer waveguide core 301 is completely located within the range of the second layer waveguide core 303, as shown in FIG. Figure 7 As shown, at this time, the width of the first layer waveguide core 301 is smaller than the width of the second layer waveguide core 303, and the second layer waveguide core 303 is located directly above the first layer waveguide core 301).

[0060] Specifically, the partial overlap means that the second layer waveguide core 303 partially covers the first layer waveguide core 301 in horizontal projection (or the first layer waveguide core 301 is partially located within the range of the second layer waveguide core 303). Figure 8 As shown, at this time, the second layer waveguide core 303 is partially located above the first layer waveguide core 301, or in other words, the central axes of the second layer waveguide core 303 and the first layer waveguide core 301 in the vertical direction are inconsistent or non-coincident.

[0061] In a specific implementation, in order to further improve the flexibility of the structure, setting and application of the heterogeneously integrated electro-optic modulator, it is proposed that the thickness of the first layer of waveguide core 301 and the second layer of waveguide core 303 may be the same or different.

[0062] Specifically, the thickness of the first layer of waveguide core 301 may be equal to the thickness of the second layer of waveguide core 303; Figure 7 As shown, the thickness of the first waveguide core 301 may be smaller than the thickness of the second waveguide core 303 ; or the thickness of the first waveguide core 301 may be larger than the thickness of the second waveguide core 303 .

[0063] In a specific implementation, the thickness of each of the first layer waveguide core 301 and the second layer waveguide core 303 may be in the range of 10 to 500 nm.

[0064] In a specific implementation, in order to further improve the flexibility of the structure, setting and application of the heterogeneous integrated electro-optic modulator, it is proposed that the thickness of the intermediate layer segment 3021 located above the first waveguide core 301 in the intermediate layer 302 is in the range of 10 to 300 nm. Figure 5 As shown, the middle layer segment 3021 is only a segment of the middle layer 302. Fig.18 , Fig.21 As shown, at this time, the middle layer section 3021 and the middle layer 302 are the same section structure.

[0065] In a specific implementation, in order to further improve the flexibility of the structure, setting and application of the heterogeneous integrated electro-optic modulator, it is proposed that the width of the intermediate layer 302 can be the same as the width of the lower cladding layer 2, and cover the first waveguide core 301 and the lower cladding layer 2, such as Figure 5 Alternatively, the width of the intermediate layer 302 may be the same as the width of the first layer waveguide core 301, as shown in FIG. Fig.18 , Fig.21 shown.

[0066] In specific implementation, in order to further improve the flexibility of the structure, setting and application of the heterogeneously integrated electro-optic modulator, it is proposed that the intermediate layer 302 can be made of a material with a refractive index smaller than that of the first waveguide core 301, such as silicon dioxide.

[0067] In specific implementation, in order to further improve the flexibility of the structure, arrangement and application of the heterogeneously integrated electro-optic modulator, it is proposed that the electrode 6 can be arranged above the electro-optic thin film layer 501 (eg Figure 1 as shown) or below (as shown Fig.16 shown).

[0068] In a specific implementation, the material of the electro-optical thin film layer 501 can be any one of the electro-optical materials such as lithium niobate, lithium tantalate, and barium titanate.

[0069] In a specific implementation, the material of the first waveguide core 301 and the second waveguide core 303 is silicon nitride, and the material of the electro-optical thin film layer 501 is lithium niobate.

[0070] In a specific implementation, in order to further improve the flexibility of the structure, setting and application of the heterogeneously integrated electro-optic modulator, any one or any combination of the refractive index of the electro-optic film layer 501, the refractive index of the waveguide core, the thickness of the waveguide core, the width of the waveguide core and the thickness of the intermediate layer 302 can be set differently to change the flexibility of the structure of the electro-optic modulator, so that the electro-optic film layer 501 and the waveguide cores of different layers from top to bottom in the stacked waveguide core 3 constitute a composite waveguide core, for example, the electro-optic film layer 501 and the second layer of waveguide core 303 constitute a composite waveguide core, or the electro-optic film layer 501 and the overall stacked waveguide core 3 constitute a composite waveguide core.

[0071] In specific implementation, under the premise that the second-layer waveguide core 303 can form a composite waveguide core with the electro-optical film layer 501, any one of the following items or any combination of items can be set to make it more inclined to the first-layer waveguide core 301 in the stacked waveguide core 3 and the electro-optical film layer 501 to form a composite waveguide core (that is, the electro-optical film layer 501 and the overall stacked waveguide core 3 form a composite waveguide core): the refractive index of the first-layer waveguide core 301 increases, the width of the first-layer waveguide core 301 increases, the thickness of the first-layer waveguide core 301 increases, the thickness of the intermediate layer 302 decreases, the refractive index of the second-layer waveguide core 303 increases, the thickness of the second-layer waveguide core 303 increases, the width of the second-layer waveguide core 303 increases, the thickness of the bonding medium layer 4 decreases, the refractive index of the electro-optical film layer 501 decreases, and the thickness of the electro-optical film layer 501 decreases.

[0072] In specific implementation, the above-mentioned preparation method of heterogeneous integrated electro-optic modulator can fully utilize CMOS compatible manufacturing process, such as Fig.24 As shown, the preparation method includes: preparing a laminated waveguide core 3, preparing or pre-preparing an electro-optic material wafer 5 having an electro-optic thin film layer 501, and bonding the electro-optic thin film layer 501 to the prepared laminated waveguide core 3 and forming an electrode 6. Examples 1 to 3 only give three preferred schemes for preparing the laminated waveguide core 3 by way of example. In other preferred schemes, the laminated waveguide core 3 can also be prepared by patterning the laminate once or multiple times. The specific method can refer to the following steps:

[0073] Step S2401: preparing the first substrate 1 and the lower cladding layer 2 in sequence;

[0074] Step S2402: sequentially forming the first waveguide core 301, the intermediate layer 302 and the second waveguide core 303 on the top surface of the lower cladding 2 to form the laminated waveguide core 3; or, forming two waveguide core layers and an intermediate material layer 3022 on the top surface of the lower cladding 2 at one time, the intermediate material layer 3022 being located between the two waveguide core layers, and patterning the two waveguide core layers and the intermediate material layer 3022 (either patterning the two waveguide core layers and the intermediate material layer once or patterning the two waveguide core layers and the intermediate material layer multiple times respectively), forming the first waveguide core 301, the intermediate layer 302 and the second waveguide core 303 to form the laminated waveguide core 3;

[0075] Step S2403: forming the bonding dielectric layer 4 on the top surface of the laminated waveguide core 3;

[0076] Step S2404: bonding one side of the electro-optical thin film layer 501 to the top surface of the bonding medium layer 4 (for example, by bonding one side of the electro-optical thin film layer 501 in the electro-optical material wafer 5 to the top surface of the bonding medium layer 4, and then removing the second substrate 503 in the electro-optical material wafer 5 to complete the bonding of the electro-optical thin film layer 501);

[0077] Step S2405 : forming an electrode 6 on or below the electro-optical thin film layer 501 .

[0078] In a specific implementation, the electrode 6 is formed above or below the electro-optical thin film layer 501, including:

[0079] When forming the electrode 6 above the electro-optic thin film layer 501, after bonding one side of the electro-optic thin film layer 501 to the top surface of the bonding dielectric layer 4, the electrode 6 is formed on the top surface of the buried oxide layer 502 above the electro-optic thin film layer 501; or

[0080] When the electrode 6 is formed below the electro-optical thin film layer 501, after the stacked waveguide core 3 is formed, grooves 7 are formed on both sides of the stacked waveguide core 3, a metal layer is deposited and patterned, and the electrode 6 is formed in the groove 7, and then the bonding dielectric layer 4 is formed on the top surface of the stacked waveguide core 3, the bonding dielectric layer 4 covers the second waveguide core 303 of the stacked waveguide core 3, the electrode 6 and the portion of the groove 7 not filled by the electrode, and the bonding dielectric layer 4 is flattened.

[0081] In specific implementation, Example 1: For the case where the widths of the first layer waveguide core 301 and the second layer waveguide core 303 are different and the two partially overlap in horizontal projection, the method for preparing the heterogeneously integrated electro-optic modulator may include the following steps:

[0082] ① Such as Figure 2 As shown, a lower cladding layer 2 is formed on a first substrate 1; Figure 3 As shown, a first waveguide core layer 3011 is formed on the lower cladding layer 2; Figure 4 As shown, the patterned first waveguide core layer 3011 becomes the first waveguide core 301; wherein the material of the first substrate 1 may be silicon; the material of the lower cladding 2 may be silicon dioxide, and the thickness may be 2 to 20 um; the material of the first waveguide core 301 may be a material having a refractive index greater than that of the lower cladding 2, such as stoichiometric silicon nitride, silicon-rich silicon nitride, silicon, etc., and the thickness of the first waveguide core 301 may range from 10 to 500 nm;

[0083] ② If Figure 5 As shown, an intermediate material layer 3022 is formed to cover the first waveguide core 301 and the lower cladding 2, and the intermediate material layer 3022 is flattened; wherein the intermediate material layer 3022 may be a material having a refractive index lower than that of the first waveguide core 301, such as silicon dioxide, etc.; at this time, the intermediate material layer 3022 is not etched, and the intermediate material layer 3022 is used as the intermediate layer 302, and the thickness of the intermediate layer section 3021 of the intermediate layer 302 located above the first waveguide core 301 may range from 10 to 300 nm;

[0084] ③ Such as Figure 6 As shown, a second waveguide core layer 3031 is formed on the intermediate layer 302; Figure 7 As shown, the second waveguide core layer 3031 is patterned to form a second waveguide core 303; wherein, the material of the second waveguide core 303 can be a material with a refractive index greater than that of the lower cladding 2 and the intermediate layer 302, such as stoichiometric silicon nitride, silicon-rich silicon nitride, silicon, etc., and the thickness of the second waveguide core 303 ranges from 10 to 500 nm; the material (refractive index, etc.), thickness, and width of the second waveguide core can be the same as or different from those of the first waveguide core 301; since the first waveguide core 301, the intermediate layer 302, and the second waveguide core 303 are formed in different steps respectively, it is convenient to prepare whether the widths of the first waveguide core 301 and the second waveguide core 303 are the same or different, and it is also convenient to prepare whether the second waveguide core 303 is located directly above the first waveguide core 301. Figure 7 Taking the example that the widths of the first waveguide core 301 and the second waveguide core 303 are different, the width of the first waveguide core 301 is smaller than the width of the second waveguide core 303, and in horizontal projection, the first waveguide core 301 is completely located within the range of the second waveguide core 303 (i.e., the second waveguide core 303 is wider than the first waveguide core 301 and is located directly above the first waveguide core 301); or Figure 8As shown, in horizontal projection, part of the first waveguide core 301 can be located within the range of the second waveguide core 303 (that is, the second waveguide core 303 covers part of the first waveguide core 301); the first waveguide core, the middle layer, and the second waveguide core constitute a stacked waveguide core;

[0085] ④ Such as Fig. 9 As shown, a bonding medium layer 4 is formed to cover the second waveguide core 303 and the middle layer 302, and the bonding medium layer 4 is flattened; wherein the bonding medium layer 4 can be a material having a refractive index smaller than that of the first waveguide core 301 and the second waveguide core 303, for example, a single layer or a stack of materials such as silicon dioxide, aluminum oxide, and bonding glue; the thickness of the bonding medium layer 4 located above the second waveguide core 303 can range from 10 to 300 nm;

[0086] ⑤ Bonding the electro-optical thin film layer 501 on the bonding medium layer 4;

[0087] The electro-optical thin film layer 501 can be bonded to one side of the bonding medium layer 4 of the first substrate 1 by bonding the electro-optical thin film layer of the wafer 5 having the electro-optical thin film layer / buried oxide layer / second substrate structure or the electro-optical thin film layer of the small piece cut from the wafer (such as Fig.10 As shown), and then remove the second substrate 503 to form (as shown Fig.11 As shown); it can also be formed by a smart ion slicing process or a wafer thinning process of a bonded electro-optic material wafer; the electro-optic thin film layer 501 can be made of lithium niobate, lithium tantalate, barium titanate and the like; the thickness of the electro-optic thin film layer 501 ranges from 100 to 500 nm;

[0088] ⑥ Such as Fig.12 As shown, an electrode 6 is formed above the buried oxide layer 502 on the electro-optical thin film layer 501. In horizontal projection, the electrode 6 is located on both sides of the laminated waveguide core 3. The material of the electrode 6 can be Au, Al, Cu, etc., the distance between the two electrodes 6 can be 4 to 10 um, and the thickness of the electrode 6 ranges from 0.5 to 2 um.

[0089] In a specific implementation, the electrode 6 can be formed on the electro-optical thin film layer 501 or below the electro-optical thin film layer 501. For example, after step ③ and before step ④ (i.e., the electrode 6 is formed after the second waveguide core 303 is formed and before the bonding medium layer 4 is formed), the electrode 6 is formed by the following process flow:

[0090] 1) After the second layer of waveguide core 303 is formed, grooves 7 are formed in the middle layer 302 and the lower cladding layer 2 on both sides of the laminated waveguide core 3, such as Fig.13 As shown;

[0091] 2) Deposit a metal layer and pattern it to form an electrode 6 in the groove 7, such as Fig.14 As shown;

[0092] 3) forming a bonding dielectric layer 4 to cover the second waveguide core 303, the intermediate layer 302, the electrode 6 and the portion of the groove 7 not filled by the electrode, and flattening the bonding dielectric layer 4, such as Fig.15 As shown;

[0093] 4) If Fig.16 As shown, the electro-optic film layer 501 is bonded to complete the preparation of the electro-optic modulator.

[0094] In specific implementation, Example 2: For the case where the upper and lower waveguide cores of the stacked waveguide core 3 are patterned in one step, the above-mentioned electro-optic modulator is prepared by the following steps:

[0095] ① Such as Fig.17 As shown, a lower cladding layer 2, a first waveguide core layer 3011, an intermediate material layer 3022 and a second waveguide core layer 3031 are sequentially formed on a first substrate 1, that is, the lower cladding layer 2, the first waveguide core layer 3011, the intermediate material layer 3022 and the second waveguide core layer 3031 are formed at one time in one step; wherein, the material of the first substrate 1 may be silicon; the material of the lower cladding layer 2 may be silicon dioxide, and the thickness of the lower cladding layer 2 may be 2 to 20 um; the material of the first waveguide core layer 3011 and the material of the second waveguide core layer 3031 may be a material having a refractive index greater than that of the lower cladding layer 2 and the intermediate material layer 3022, such as stoichiometric silicon nitride, silicon-rich silicon nitride, silicon, etc., the thickness range of the first waveguide core layer 3011 and the second waveguide core layer 3031 is 10 to 500 nm, and the materials (refractive index, etc.) and thicknesses of the two may be the same or different; the thickness range of the intermediate material layer 3022 is 10 to 300 nm;

[0096] ② If Fig.18 As shown, the second waveguide core layer 3031, the intermediate material layer 3022 and the first waveguide core layer 3011 are patterned to form the second waveguide core 303, the intermediate layer 302 and the first waveguide core 301; wherein the laminated waveguide core 3 is composed of the first waveguide core 301, the intermediate layer 302 and the second waveguide core 303 from bottom to top; specifically, although the lower cladding layer 2, the first waveguide core layer 3011, the intermediate material layer 3022 and the second waveguide core layer 3031 are formed at one time in one step, in the process of forming the laminated waveguide core 3, the second waveguide core layer 3031, the intermediate material layer 3022 and the first waveguide core layer 3011 can be etched at one time to form the laminated waveguide core 3 with the same width of the first waveguide core 301, the intermediate layer 302 and the second waveguide core 303, as shown in FIG. Fig.18 As shown; the second waveguide core layer 3031, the intermediate material layer 3022 and the first waveguide core layer 3011 may also be etched in sequence to form a laminated waveguide core 3 with different widths of the first waveguide core 301, the intermediate layer 302 and the second waveguide core 303;

[0097] ③ Such as Fig.19 As shown, based on Fig.18 The bonding dielectric layer 4 is formed by a structure covering the second waveguide core 303 and the lower cladding 2 of the stacked waveguide core 3, and the bonding dielectric layer 4 is flattened; wherein the bonding dielectric layer 4 can be a material having a refractive index smaller than that of the first waveguide core 301 and the second waveguide core 303, such as a single layer or a stack of materials such as silicon dioxide, aluminum oxide, and bonding glue; the thickness of the dielectric layer segment 401 of the bonding dielectric layer 4 located above the second waveguide core 303 is in the range of 10 to 300 nm;

[0098] ④ Bonding the electro-optical thin film layer 501 on the bonding dielectric layer 4; forming an electrode 6 above the buried oxide layer 502 on the electro-optical thin film layer 501, and completing the preparation of the above electro-optical modulator, as shown in FIG. Figure 1 As shown; wherein the electro-optical thin film layer 501 can be formed by bonding one side of the electro-optical thin film layer of a wafer 5 having an electro-optical thin film layer 501 / buried oxide layer 502 / second substrate 503 structure or a small piece cut from the wafer to one side of the bonding medium layer 4 of the first substrate 1, and then removing the second substrate 503, and then forming an electrode 6 (such as Figure 1 As shown); it can also be formed by a smart ion slicing process or a wafer thinning process of a bonded electro-optic material wafer; the electro-optic thin film layer 501 can be lithium niobate, lithium tantalate, barium titanate, etc.; the thickness of the electro-optic thin film layer 501 ranges from 100 to 500 nm; the material of the electrode 6 can be Au, Al, Cu, etc., the distance between the two electrodes 6 is 4 to 10 um, and the thickness of the electrode 6 ranges from 0.5 to 2 um;

[0099] Specifically, the electrode 6 may be located on the electro-optical thin film layer 501 (eg Figure 1 As shown), it may also be located under the electro-optical thin film layer 501, and the electrode 6 may be formed according to steps 1) to 4) of Example 1 (the electrode 6 is made after the stacked waveguide core 3 is formed and before the bonding dielectric layer 4 is formed, at this time, grooves 7 are formed on the lower cladding 2 on both sides of the stacked waveguide core 3, and the electrode 6 is formed in the groove 7, and then the bonding dielectric layer 4 is formed to cover the second waveguide core 303 of the stacked waveguide core 3, the lower cladding 2, the electrode 6 and the portion of the groove 7 not filled with the electrode).

[0100] In specific implementation, Example 3: For the case where the lower waveguide core of the laminated waveguide core 3 is wider than the upper waveguide core, and the upper waveguide core is completely located within the range of the lower waveguide core in horizontal projection, the above-mentioned electro-optic modulator is prepared by the following steps:

[0101] ① On the first substrate 1, a lower cladding layer 2, a first waveguide core layer 3011, an intermediate material layer 3022 and a second waveguide core layer 3031 are formed in sequence at one time. Fig.17As shown; wherein, the material of the first substrate 1 may be silicon; the material of the lower cladding 2 may be silicon dioxide, and the thickness of the lower cladding 2 is 2 to 20 um; the material of the first waveguide core layer 3011 and the material of the second waveguide core layer 3031 may be materials having a refractive index greater than that of the lower cladding 2 and the intermediate material layer 3022, such as stoichiometric silicon nitride, silicon-rich silicon nitride, silicon, etc., the thickness range of the first waveguide core layer 3011 and the second waveguide core layer 3031 is 10 to 500 nm, and the materials (refractive index, etc.) and thicknesses of the two may be the same or different; the thickness of the intermediate material layer 3022 is 10 to 300 nm;

[0102] ② If Fig. 20 As shown, the second waveguide core layer 3031 is patterned to form a second layer of waveguide core 303;

[0103] ③ Such as Fig.21 As shown, the intermediate material layer 3022 and the first waveguide core layer 3011 are patterned to form the first waveguide core 301 and the intermediate layer 302; specifically, although the lower cladding layer 2, the first waveguide core layer 3011, the intermediate material layer 3022 and the second waveguide core layer 3031 are formed at one time in one step, in the process of forming the laminated waveguide core 3, the second waveguide core layer 3031, the intermediate material layer 3022 and the first waveguide core layer 3011 can also be etched in sequence to form the laminated waveguide core 3 in which the widths of the first waveguide core 301, the intermediate layer 302 and the second waveguide core 303 are different (mainly the case where the width of the first waveguide core 301 is greater than the width of the second waveguide core 303); as shown Fig.21 As shown, the width of the first layer waveguide core 301 is greater than the width of the second layer waveguide core 303, and the width of the middle layer 302 is equal to the width of the first layer waveguide core 301;

[0104] ④ Such as Fig. 22 As shown, based on Fig.21 The bonding medium layer 4 is formed by a structure covering the second waveguide core 303, the middle layer 302 and the lower cladding 2, and the bonding medium layer 4 is flattened; wherein the bonding medium layer 4 can be a material having a refractive index smaller than that of the first waveguide core 301 and the second waveguide core 303, for example, a single layer or a stack of materials such as silicon dioxide, aluminum oxide, and bonding glue; the thickness of the bonding medium layer 4 located above the second waveguide core 303 is in the range of 10 to 300 nm;

[0105] ⑤ Such as Fig.23As shown, an electro-optic thin film layer 501 is bonded to the bonding dielectric layer 4; an electrode 6 is formed above the buried oxide layer 502 on the electro-optic thin film layer 501 to complete the preparation of the above-mentioned electro-optic modulator; wherein the electro-optic thin film layer 501 can be bonded to one side of the bonding dielectric layer 4 of the first substrate 1 by bonding the electro-optic thin film layer 501 / buried oxide layer 502 / second substrate 503 on one side of the wafer 5 or the electro-optic thin film layer 501 of a small piece cut from the wafer, and then after removing the second substrate 503, an electrode 6 is formed above the buried oxide layer 502 (as shown in FIG. Fig.23 As shown); it can also be formed by a smart ion slicing process or a wafer thinning process of a bonded electro-optic material wafer; the electro-optic thin film layer 501 can be lithium niobate, lithium tantalate, barium titanate, etc.; the thickness of the electro-optic thin film layer 501 is 100 to 500nm; the material of the electrode 6 can be Au, Al, Cu, etc., the distance between the two electrodes 6 is 4 to 10um, and the thickness of the electrode 6 ranges from 0.5 to 2um;

[0106] Specifically, the electrode 6 may be located on the electro-optical thin film layer 501 (eg Fig.23 As shown), it may also be located under the electro-optical thin film layer 501, and the electrode 6 may be formed according to steps 1) to 4) of Example 1 (the electrode 6 is made after the stacked waveguide core 3 is formed and before the bonding dielectric layer 4 is formed, at this time, grooves 7 are formed on the lower cladding 2 on both sides of the stacked waveguide core 3, and the electrode 6 is formed in the groove 7, and then the bonding dielectric layer 4 is formed to cover the second waveguide core 303 of the stacked waveguide core 3, the intermediate layer 302, the lower cladding 2, the electrode 6 and the portion of the groove 7 not filled with the electrode).

[0107] The embodiments of the present invention achieve the following technical effects: the present application adopts heterogeneous integration of stacked waveguide cores and electro-optical films to form a composite waveguide core or an electro-optical modulation device. Since the first waveguide core and the second waveguide core of the stacked waveguide can have different or the same materials (properties such as refractive index), width, thickness, etc., the composite waveguide or electro-optical modulation device composed of the stacked waveguide core and the electro-optical film can have higher flexibility and application expansion.

[0108] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the embodiments of the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A heterogeneously integrated electro-optic modulator, characterized in that: The heterogeneously integrated electro-optic modulator comprises, from bottom to top: A first substrate (1); A lower cladding layer (2), the lower cladding layer (2) being located on the top surface of the first substrate (1); A laminated waveguide core (3), the laminated waveguide core (3) being located on the top surface of the lower cladding (2), wherein the laminated waveguide core (3) comprises a first layer of waveguide core (301), an intermediate layer (302) and a second layer of waveguide core (303) which are laminated, and the intermediate layer (302) is arranged between the first layer of waveguide core (301) and the second layer of waveguide core (303); A bonding dielectric layer (4), the bonding dielectric layer (4) covering the top surface of the laminated waveguide core (3); An electro-optical film layer (501), one side of the electro-optical film layer (501) being bonded to the top surface of the bonding medium layer (4), wherein the electro-optical film layer (501) and at least one layer of waveguide core in the stacked waveguide core (3) form a composite waveguide core, and any one or any combination of the different refractive indices of the electro-optical film layer (501), the different refractive indices of the waveguide cores, the different thicknesses of the waveguide cores, the different widths of the waveguide cores, and the different thicknesses of the intermediate layers (302) enables the electro-optical film layer (501) and the waveguide cores of different layers from top to bottom in the stacked waveguide core (3) to form a composite waveguide core; An electrode (6), wherein the electrode (6) is arranged above or below the electro-optical thin film layer (501), and in horizontal projection, the electrode (6) is located on both sides of the laminated waveguide core (3).

2. The heterogeneously integrated electro-optic modulator according to claim 1, characterized in that: The materials of the first waveguide core (301) and the second waveguide core (303) are the same or different, and the refractive index of each of the first waveguide core (301) and the second waveguide core (303) is respectively greater than the refractive index of the lower cladding (2) and the refractive index of the intermediate layer (302).

3. The heterogeneously integrated electro-optic modulator according to claim 1, characterized in that: The widths of the first layer of waveguide cores (301) and the second layer of waveguide cores (303) are the same or different, and in horizontal projection, the first layer of waveguide cores (301) and the second layer of waveguide cores (303) overlap.

4. The heterogeneously integrated electro-optic modulator according to claim 1, characterized in that: The thickness of the first layer waveguide core (301) and the second layer waveguide core (303) are the same or different.

5. The heterogeneously integrated electro-optic modulator according to claim 1, characterized in that: The thickness of each of the first layer waveguide core (301) and the second layer waveguide core (303) is in the range of 10 to 500 nm.

6. The heterogeneously integrated electro-optic modulator according to claim 1, characterized in that: The thickness of the intermediate layer segment (3021) in the intermediate layer (302) located above the first waveguide core (301) is in the range of 10 to 300 nm.

7. The heterogeneously integrated electro-optic modulator according to claim 1, characterized in that: The width of the intermediate layer is the same as that of the lower cladding layer (2), and covers the first waveguide core (301) and the lower cladding layer (2); or the width of the intermediate layer (302) is the same as that of the first waveguide core (301).

8. The heterogeneously integrated electro-optic modulator according to any one of claims 1 to 7, characterized in that: The material of the first waveguide core (301) and the second waveguide core (303) is silicon nitride, and the material of the electro-optical thin film layer (501) is lithium niobate.

9. A method for preparing a heterogeneously integrated electro-optic modulator according to any one of claims 1 to 8, characterized in that: include: The first substrate (1) and the lower cladding layer (2) are prepared in sequence; The first waveguide core (301), the intermediate layer (302) and the second waveguide core (303) are sequentially formed on the top surface of the lower cladding (2) to form the stacked waveguide core (3); or, two waveguide core layers and an intermediate material layer (3022) are formed on the top surface of the lower cladding (2) at one time, the intermediate material layer (3022) being located between the two waveguide core layers, and the two waveguide core layers and the intermediate material layer (3022) are patterned to form the first waveguide core (301), the intermediate layer (302) and the second waveguide core (303) to form the stacked waveguide core (3); forming the bonding medium layer (4) on the top surface of the laminated waveguide core (3); Bonding one side of the electro-optical thin film layer (501) to the top surface of the bonding medium layer (4); An electrode (6) is formed above or below the electro-optical thin film layer (501).

10. The preparation method according to claim 9, characterized in that: An electrode (6) is formed above or below the electro-optical thin film layer (501), comprising: When forming the electrode (6) above the electro-optical thin film layer (501), after bonding one side of the electro-optical thin film layer (501) to the top surface of the bonding medium layer (4), the electrode (6) is formed on the top surface of the buried oxide layer (502) above the electro-optical thin film layer (501); or When forming an electrode (6) below the electro-optical thin film layer (501), after forming the stacked waveguide core (3), grooves (7) are formed on both sides of the stacked waveguide core (3), a metal layer is deposited and patterned, an electrode (6) is formed in the groove (7), and then the bonding dielectric layer (4) is formed on the top surface of the stacked waveguide core (3), the bonding dielectric layer (4) covers the second waveguide core (303) of the stacked waveguide core (3), the electrode (6) and the portion of the groove (7) not filled with the electrode, and the bonding dielectric layer (4) is flattened.

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