A lithium niobate waveguide with weak phase drift

Abstract

The present application discloses a lithium niobate waveguide with weak phase drift, which includes a lithium niobate layer, a metal electrode, and a substrate layer. The lithium niobate layer includes a lithium niobate central ridge and lithium niobate extension surfaces extending to both sides of the lithium niobate central ridge. A metal oxide layer is provided on the upper surface of the lithium niobate central ridge. The substrate layer is located on the lower surface of the lithium niobate layer and is made of silicon, silicon dioxide, a multi-layer material of silicon and silicon dioxide, or a multi-layer material of silicon dioxide, metal, and silicon, so as to further achieve the purpose of suppressing phase drift. Compared with other doping or other structures, the manufacturing method of this structure is simple, and at the same time, a very good phase drift suppression effect is produced.

Description

Technical Field

[0001] This application relates to the field of electronic communications, and particularly to a lithium niobate waveguide with weak phase drift. Background Art

[0002] Lithium niobate is one of the materials widely used in optoelectronic devices. The various optoelectronic properties of lithium niobate, such as low operating voltage, low transmission loss, etc., make it used to manufacture a variety of optoelectronic devices, such as optical waveguides, high-speed optical modulators, optical frequency converters, etc. In recent years, the development of thin-film lithium niobate-on-insulator has enabled thin-film lithium niobate optical waveguides compatible with modern integrated circuit manufacturing processes to be widely studied. Thin-film lithium niobate optical waveguides can be applied to high-speed optoelectronic devices, such as Mach-Zehnder optical modulators and microring resonators.

[0003] Integrated optical devices such as modulators and optical switches require a suitable bias operating point to work properly, that is, to apply a suitable phase bias point to the device. For example, when a lithium niobate modulator is applied to an optical communication system, the bit error rate needs to be reduced, which requires a basically stable bias operating point; when applied to a CATV system, interference requires the best linearity near the π / 2 phase bias operating point; when applied to an optical switch, a suitable bias voltage is also required to adjust the maximum or minimum light transmittance to map the zero or π phase bias point. However, the phase stability of a lithium niobate waveguide modulator is affected by a series of external environments, such as external electric fields, mechanical forces, temperature, etc., causing the modulation phase to drift, and further causing the DC bias zero point of the device to drift in amplitude or frequency, large or small. This drift will cause the lithium niobate waveguide device to fail, limiting the application of the lithium niobate waveguide device in the actual environment. Summary of the Invention

[0004] The main purpose of this application is to provide a lithium niobate waveguide with weak phase drift, achieving the purpose of suppressing phase drift and enhancing the stability of device operation.

[0005] To achieve the above purpose, this application provides a lithium niobate waveguide with weak phase drift, including a lithium niobate layer, a metal electrode, and a substrate layer. The lithium niobate layer includes a lithium niobate central ridge and lithium niobate extension surfaces extending from both sides of the lithium niobate central ridge. A metal oxide layer is provided on the upper surface of the lithium niobate central ridge. The substrate layer is located on the lower surface of the lithium niobate layer, and the substrate layer is made of silicon, silicon dioxide, a multi-layer material of silicon and silicon dioxide, or a multi-layer material of silicon dioxide, metal, and silicon.

[0006] Preferably, a metal oxide layer is provided on the upper surface of the lithium niobate extension surface and the side surface of the central ridge.

[0007] Preferably, it further includes a covering layer which is located on the upper surfaces of the metal oxide layer and the lithium niobate layer without the metal oxide covering, and the covering layer is composed of silicon dioxide.

[0008] Preferably, the metal electrode is connected to the upper surface of the metal oxide layer.

[0009] Preferably, after the metal electrode penetrates through the part or all of the metal oxide layer and / or part or all of the lithium niobate extended surface and / or part or all of the lower substrate layer, it is connected to the surface of the lowermost layer that has been penetrated.

[0010] Preferably, the metal electrode is connected to the upper surface of the lithium niobate extended surface.

[0011] Preferably, after the metal electrode penetrates through the part or all of the lithium niobate extended surface and / or part or all of the lower substrate layer, it is connected to the surface of the lowermost layer that has been penetrated.

[0012] Preferably, after the metal electrode penetrates through the part or all of the covering layer and / or part or all of the metal oxide layer and / or part or all of the lithium niobate extended surface and / or part or all of the lower substrate layer, it is connected to the surface of the lowermost layer that has been penetrated.

[0013] Preferably, the top surface of the metal electrode is higher than or lower than or equal to the surface height of the covering layer.

[0014] Preferably, the metal electrode is located within the substrate layer.

[0015] Preferably, the outer surface of the metal oxide layer is a wavy structure, and the maximum thickness of the metal oxide layer is less than 2 μm.

[0016] Preferably, the metal oxide layer is alumina, hafnium oxide, tantalum oxide, zirconium dioxide or titanium dioxide, etc.

[0017] Preferably, the thickness of the lithium niobate central ridge is 0.2 - 3 μm, the thickness of the lithium niobate extended surface is 0.1 - 1 μm, and the width of the lithium niobate central ridge is 0.3 - 3 μm.

[0018] The beneficial effect of this application is that by covering or partially covering the surface of the lithium niobate waveguide with a layer of metal oxide such as alumina, hafnium oxide, tantalum oxide, zirconium dioxide or titanium dioxide to absorb free electrons in the material, the metal electrode can be either arranged on the surface of the metal oxide layer or directly on the surface of the lithium niobate layer, which can further achieve the purpose of suppressing phase drift. The lithium niobate waveguide has a simple structure. Compared with other doping or other structures, the manufacturing method of this structure is simple, and at the same time, it produces a very good phase drift suppression effect. Brief Description of the Drawings

[0019] The accompanying drawings, which form a part of this application, are used to provide a further understanding of this application, making other features, objectives, and advantages of this application more obvious. The schematic embodiments of the accompanying drawings of this application and their descriptions are used to explain this application and do not constitute an improper limitation to this application. In the drawings:

[0020] Figure 1 is the first specific embodiment of a lithium niobate waveguide with weak phase drift;

[0021] Figure 2 is the second specific embodiment of a lithium niobate waveguide with weak phase drift;

[0022] Figure 3 is the third specific embodiment of a lithium niobate waveguide with weak phase drift;

[0023] Figure 4 is the fourth specific embodiment of a lithium niobate waveguide with weak phase drift.

[0024] Figure 5 is the fourth specific embodiment of a lithium niobate waveguide with weak phase drift.

[0025] Figure 6 is the fourth specific embodiment of a lithium niobate waveguide with weak phase drift.

[0026] 1 - lithium niobate layer, 2 - metal oxide layer, 3 - metal electrode, 4 - substrate layer, 11 - lithium niobate center ridge, 12 - lithium niobate extension surface, 5 - cover layer. Detailed implementation manners

[0027] To enable those skilled in the art to better understand the solution of this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this application.

[0028] It should be noted that the terms "first", "second", etc. in the specification and claims of this application and the above accompanying drawings are used to distinguish similar objects and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so as to describe the embodiments of this application here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0029] In this application, the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal", etc. is based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe this application and its embodiments, and are not used to limit that the indicated devices, elements or components must have a specific orientation, or be constructed and operated in a specific orientation.

[0030] Moreover, in addition to being used to represent the orientation or positional relationship, some of the above terms may also be used to represent other meanings. For example, the term "upper" may also be used to represent a certain attachment relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to the specific circumstances.

[0031] In addition, the meaning of the term "plurality" should be two or more.

[0032] It should be noted that, without conflict, the embodiments and features in the embodiments of this application can be combined with each other. The following will detail this application with reference to the drawings and in combination with the embodiments.

[0033] Embodiment 1:

[0034] As Figure 1 shown, the present invention provides a lithium niobate waveguide with weak phase drift, including a lithium niobate layer 1 and a metal electrode 3. The lithium niobate layer 1 includes a lithium niobate central ridge 11 and lithium niobate extension surfaces 12 extending on both sides of the lithium niobate central ridge 11. A metal oxide layer 2 is provided on the upper surface of the lithium niobate central ridge 11. The base layer 4 is located on the lower surface of the lithium niobate layer. The base layer is made of silica material. The metal electrode 3 is connected to the upper surface of the lithium niobate extension surface 12. The thickness of the lithium niobate central ridge is 0.2 μm, the thickness of the lithium niobate extension surface is 0.1 μm, and the width of the lithium niobate central ridge is 0.3 μm. The metal oxide layer is alumina.

[0035] Embodiment 2:

[0036] As Figure 2As shown in the figure, the present invention provides a lithium niobate waveguide with weak phase drift, including a lithium niobate layer and metal electrodes. The lithium niobate layer includes a lithium niobate central ridge and lithium niobate extension surfaces extending from both sides of the lithium niobate central ridge. A metal oxide layer is provided on the upper surface of the lithium niobate central ridge, and a metal oxide layer 3 is provided on the upper surface of the lithium niobate extension surfaces. The base layer 4 is located on the lower surface of the lithium niobate layer. The base layer is made of silicon material. The metal electrode 3 is connected to the upper surface of the metal oxide layer 2. The thickness of the lithium niobate central ridge is 1.2 μm, the thickness of the lithium niobate extension surfaces is 0.6 μm, and the width of the lithium niobate central ridge is 1.5 μm. The metal oxide layer is alumina or hafnium oxide.

[0037] Example 3:

[0038] As Figure 3 shown in the figure, the present invention provides a lithium niobate waveguide with weak phase drift, including a lithium niobate layer 1, metal electrodes 3, and a base layer 4. The lithium niobate layer includes a lithium niobate central ridge and lithium niobate extension surfaces extending from both sides of the lithium niobate central ridge. A metal oxide layer is provided on the upper surface of the lithium niobate central ridge. The base layer 4 is located on the lower surface of the lithium niobate layer. The metal electrode passes through the lithium niobate extension surfaces and is connected to the base layer 4. The base layer 4 is made of silicon, silicon dioxide, a multi-layer material of silicon and silicon dioxide, or a multi-layer material of silicon dioxide, metal, and silicon. The thickness of the lithium niobate central ridge is 3 μm, the thickness of the lithium niobate extension surfaces is 1 μm, and the width of the lithium niobate central ridge is 3 μm. The metal oxide layer is tantalum oxide or zirconium dioxide.

[0039] Example 4:

[0040] As Figure 4 shown in the figure, the present invention provides a lithium niobate waveguide with weak phase drift, including a lithium niobate layer 1, metal electrodes 3, a base layer 4, and a covering layer 5. The lithium niobate layer 1 includes a lithium niobate central ridge and lithium niobate extension surfaces extending from both sides of the lithium niobate central ridge. A metal oxide layer is provided on the upper surface of the lithium niobate central ridge. The base layer is located on the lower surface of the lithium niobate layer. The metal electrode 3 is connected to the lithium niobate layer 1. The covering layer 5 is provided on the upper surface of the metal oxide layer. The base layer is made of silicon dioxide material. The metal electrode is located within the base layer 4. The thickness of the lithium niobate central ridge is 0.6 μm, the thickness of the lithium niobate extension surfaces is 0.5 μm, and the width of the lithium niobate central ridge is 0.8 μm. The metal oxide layer is alumina, hafnium oxide, tantalum oxide, zirconium dioxide, or titanium dioxide.

[0041] Example 5:

[0042] As Figure 5As shown in the figure, the present invention provides a lithium niobate waveguide with weak phase drift, which includes a lithium niobate layer 1, a metal electrode 3, a substrate layer 4, and a covering layer 5. The lithium niobate layer includes a lithium niobate central ridge and lithium niobate extending surfaces extending from both sides of the lithium niobate central ridge. A metal oxide layer is provided on the upper surface of the lithium niobate central ridge. A metal oxide layer is provided on the upper surface of the lithium niobate extending surfaces. The substrate layer 4 is located on the lower surface of the lithium niobate layer 1. The substrate layer is made of a silica material. The metal electrode 4 is connected to the metal oxide layer 2. The covering layer 5 is located on the upper surface of the metal oxide layer 2. The metal electrode 3 is located within the covering layer 5. The thickness of the lithium niobate central ridge is 0.8 μm, and the thickness of the lithium niobate extending surfaces is 0.5 μm. The width of the lithium niobate central ridge is 1.2 μm. The metal oxide layer is alumina, hafnium oxide, tantalum oxide, zirconium dioxide, or titanium dioxide.

[0043] Example 6:

[0044] As Figure 6 As shown in the figure, the present invention provides a lithium niobate waveguide with weak phase drift, which includes a lithium niobate layer 1, a metal electrode 3, a substrate layer 4, and a covering layer 5. The lithium niobate layer includes a lithium niobate central ridge and lithium niobate extending surfaces extending from both sides of the lithium niobate central ridge. A metal oxide layer is provided on the upper surface of the lithium niobate central ridge. A metal oxide layer is provided on the upper surface of the lithium niobate extending surfaces. The substrate layer 4 is located on the lower surface of the lithium niobate layer 1. The metal electrode passes through the lithium niobate extending surface and is connected to the substrate layer 4. The covering layer 5 is located on the upper surface of the metal oxide layer. The substrate layer 4 is made of a multi-layer material of silicon and silica. The metal electrode is located within the substrate layer 4. The thickness of the lithium niobate central ridge is 0.6 μm, and the thickness of the lithium niobate extending surfaces is 0.5 μm. The width of the lithium niobate central ridge is 0.8 μm. The metal oxide layer is alumina, hafnium oxide, tantalum oxide, zirconium dioxide, or titanium dioxide, etc.

[0045] By covering or partially covering a layer of metal oxide layer, such as alumina, hafnium oxide, tantalum oxide, zirconium dioxide, or titanium dioxide, etc. on the surface of the lithium niobate waveguide to absorb free electrons in the material, the metal electrode can be arranged on the surface of the metal oxide layer, or directly on the surface of the lithium niobate layer, or penetrate through the metal oxide layer and the lithium niobate layer to be arranged on the surface of the silica substrate layer, so as to further achieve the purpose of suppressing phase drift. The structure of this lithium niobate waveguide is simple. Compared with other doping or other structures, the manufacturing method of this structure is simple, and at the same time, it produces a very good phase drift suppression effect.

[0046] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A lithium niobate waveguide with weak phase drift, characterized in that , including a lithium niobate layer, a metal electrode, and a base layer. The lithium niobate layer includes a lithium niobate central ridge and lithium niobate extending surfaces extending on both sides of the lithium niobate central ridge. A metal oxide layer is provided on the upper surface of the lithium niobate central ridge. The base layer is located on the lower surface of the lithium niobate layer. The base layer is made of silicon, silicon dioxide, a multi-layer material of silicon and silicon dioxide, or a multi-layer material of silicon dioxide, metal, and silicon; A metal oxide layer is provided on the upper surface of the lithium niobate extending surface and the side surface of the central ridge; The metal oxide layer is hafnium oxide, tantalum oxide, zirconium dioxide, or titanium dioxide; It further includes a cover layer. The cover layer is located on the upper surfaces of the metal oxide layer and the lithium niobate layer not covered by the metal oxide layer. The cover layer is composed of silicon dioxide; After the metal electrode passes through the part or all of the cover layer and / or part or all of the metal oxide layer and / or part or all of the lithium niobate extending surface and / or part or all of the lower base layer, it is connected to the surface of the lowermost layer that has been passed through; The top surface of the metal electrode is higher than, lower than, or equal to the surface height of the cover layer; The metal electrode is located within the base layer.

2. The lithium niobate waveguide with weak phase drift according to claim 1, characterized in that , The metal electrode is connected to the upper surface of the metal oxide layer.

3. A lithium niobate waveguide with weak phase drift according to claim 1, characterized in that , After the metal electrode passes through the part or all of the metal oxide layer and / or part or all of the lithium niobate extending surface and / or part or all of the lower base layer, it is connected to the surface of the lowermost layer that has been passed through.

4. A lithium niobate waveguide with weak phase drift according to claim 1, characterized in that , The metal electrode is connected to the upper surface of the lithium niobate extending surface.

5. A lithium niobate waveguide with weak phase drift according to claim 1, characterized in that , After the metal electrode passes through the part or all of the lithium niobate extending surface and / or part or all of the lower base layer, it is connected to the surface of the lowermost layer that has been passed through.

6. The lithium niobate waveguide with weak phase drift according to claim 1, characterized in that , The maximum thickness of the metal oxide layer is less than 2 um.

7. A lithium niobate waveguide with weak phase drift according to claim 1, characterized in that , The thickness of the lithium niobate central ridge is 0.2 - 3 um, the thickness of the lithium niobate extending surface is 0.1 - 1 um, and the width of the lithium niobate central ridge is 0.3 - 3 um.

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