Optical modulation module and optical modulator

Abstract

Provided in the present disclosure are an optical modulation module and an optical modulator. The optical modulation module comprises a waveguide layer. The waveguide layer comprises: a flat plate portion; a first protruding portion and a second protruding portion, which are located on the flat plate portion and extend in a first direction, a distance between top faces of the first protruding portion and the second protruding portion and a bottom face of the flat plate portion being defined as H1; and a ridge portion, which is located on the flat plate portion and extends in the first direction and is located between the first protruding portion and the second protruding portion, wherein a first trench is formed between the ridge portion and the first protruding portion, and a second trench is formed between the ridge portion and the second protruding portion, a distance between a top face of the ridge protruding portion and the bottom face of the flat plate portion being defined as H2, where H2 > H1.

Description

Optical modulation module and optical modulator

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure claims priority to Chinese patent application No. 2023107941999, filed on June 29, 2023, the entire contents of which are incorporated by reference into this disclosure in their entirety. Technical Field

[0003] The present disclosure relates to the field of optical waveguide technology, and in particular to an optical modulation module and an optical modulator. Background Art

[0004] An optical waveguide is a dielectric device that guides light waves through its propagation, also known as a dielectric optical waveguide. Rectangular waveguides and ridge waveguides are two common waveguide structures. Rectangular waveguides can better confine and guide light transmission, but the interaction between the transmitted light and external fields (such as an applied electric field) is relatively weak. Ridge waveguides, on the other hand, have a relatively strong interaction between the transmitted light and external fields (such as an applied electric field), but their ability to confine and guide light transmission along their ridges is relatively weak.

[0005] Summary of the Invention

[0006] The embodiments of the present disclosure provide an optical modulation module and an optical modulator to enhance the limiting and guiding capability of the waveguide layer of the optical modulator for light transmission, thereby improving the performance of the device.

[0007] According to one aspect of the present disclosure, an optical modulation module is provided, including a waveguide layer, the waveguide layer including: a flat plate portion; a first protruding portion and a second protruding portion, the first protruding portion and the second protruding portion being located above the flat plate portion and extending along a first direction, the top surfaces of the first protruding portion and the second protruding portion being spaced apart from the bottom surface of the flat plate portion by a distance H1; and a ridge portion, the first protruding portion and the second protruding portion being located above the flat plate portion and extending along the first direction, the ridge portion and the second protruding portion being spaced apart, the first groove being formed between the ridge portion and the first protruding portion, the second groove being formed between the ridge portion and the second protruding portion, the top surface of the ridge portion being spaced apart from the bottom surface of the flat plate portion by a distance H2, wherein H2>H1.

[0008] In some embodiments, along the first direction, the depths of the first trench and the second trench gradually decrease, and / or the widths of the first trench and the second trench gradually decrease.

[0009] In some embodiments, along the first direction, the depths of the first trench and the second trench gradually increase, and / or the widths of the first trench and the second trench gradually increase.

[0010] In some embodiments, the lengths of the first trench and the second trench along the first direction are equal to or less than the length of the ridge along the first direction.

[0011] In some embodiments, the optical modulation module further includes: a substrate; an isolation layer located above the substrate, wherein the waveguide layer is formed above the isolation layer; and a covering layer covering the waveguide layer, wherein the refractive index of the material of the isolation layer and the covering layer is less than the refractive index of the material of the waveguide layer.

[0012] In some embodiments, the cover layer covers the ridge, the first groove, and the second groove.

[0013] In some embodiments, the covering layer further covers at least a portion of the first protrusion and at least a portion of the second protrusion.

[0014] In some embodiments, the light modulation module further includes: an electrode layer formed on a surface of the cover layer; or an electrode layer formed on a surface of at least one of the first protrusion and the second protrusion.

[0015] In some embodiments, the optical modulation module includes an electro-optical modulation module or a thermo-optical modulation module.

[0016] According to one aspect of the present disclosure, there is provided an optical modulator comprising the optical modulation module according to the aforementioned aspect.

[0017] According to one or more embodiments of the present disclosure, the first and second grooves can prevent the diffusion of the optical mode field in the second direction, thereby concentrating light propagation in the region where the ridge is located. Therefore, the design scheme of the embodiments of the present disclosure can enhance the waveguide layer's ability to confine and guide light transmission, thereby improving device performance.

[0018] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present disclosure, nor are they intended to limit the scope of the present disclosure. Other features of the present disclosure will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Further details, features and advantages of the present disclosure are disclosed in the following description of exemplary embodiments in conjunction with the accompanying drawings, in which:

[0020] FIG1 is a schematic cross-sectional view of an optical modulation module according to some exemplary embodiments of the present disclosure;

[0021] FIG2 is a schematic cross-sectional view of an optical modulation module according to some exemplary embodiments of the present disclosure;

[0022] FIG3 is a schematic cross-sectional view of an optical modulation module according to some exemplary embodiments of the present disclosure;

[0023] FIG4 is a schematic cross-sectional view of an optical modulation module according to some exemplary embodiments of the present disclosure;

[0024] FIG5A is a schematic diagram of a three-dimensional structure of an optical modulation module according to some exemplary embodiments of the present disclosure;

[0025] FIG5B is a schematic diagram of a three-dimensional structure of an optical modulation module according to some exemplary embodiments of the present disclosure;

[0026] FIG5C is a schematic diagram of a three-dimensional structure of an optical modulation module according to some exemplary embodiments of the present disclosure; and

[0027] FIG5D is a schematic diagram of a three-dimensional structure of an optical modulation module according to some exemplary embodiments of the present disclosure.

[0028] Reference Signs: 100 - optical modulation module 101 - substrate 102 - isolation layer 103 - waveguide layer 104 - cover layer 105 - electrode layer 30 - slab portion 31 - first protrusion 32 - second protrusion 33 - ridge 34 - first groove 35 - second groove DETAILED DESCRIPTION

[0029] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present disclosure. Therefore, the drawings and description are to be considered as illustrative in nature and not restrictive.

[0030] A ridge waveguide is a type of optical waveguide with excellent properties, including a low main mode cutoff frequency, wide bandwidth, and low impedance. One type of ridge waveguide in related technology comprises an integrally fabricated planar layer and a ridged convex layer positioned above it. While the interaction between propagating light and external fields (such as an applied electric field) in this type of ridge waveguide is relatively strong, the ridge waveguide's ability to confine and guide light along its ridge is relatively weak.

[0031] The embodiments of the present disclosure provide an optical modulation module and an optical modulator to enhance the limiting and guiding capability of the waveguide layer of the optical modulator for light transmission, thereby improving the performance of the device.

[0032] As shown in FIG1 , an optical modulation module 100 provided in some embodiments of the present disclosure includes a waveguide layer 103. The waveguide layer 103 includes a flat plate portion 30, a first protruding portion 31, a second protruding portion 32, and a ridge 33. The first protruding portion 31 and the second protruding portion 32 are located above the flat plate portion 30 and extend along a first direction (not shown; the first direction is perpendicular to the paper). The distance between the top surfaces of the first and second protruding portions 31 and 32 and the bottom surface of the flat plate portion 30 is H1. The ridge 33 is located above the flat plate portion 30 and extends along the first direction and is located between the first and second protruding portions 31 and 32. A first groove 34 is formed between the ridge 33 and the first protruding portion 31, and a second groove 35 is formed between the ridge 33 and the second protruding portion 32. The distance between the top surface of the ridge 33 and the bottom surface of the flat plate portion 30 is H2, where H2>H1.

[0033] The first direction can be the direction of light transmission or the opposite direction of light transmission. In the optical modulation module 100 of the embodiment of the present disclosure, the ridge 33 of the waveguide layer 103 is separated from the first protrusion 31 by a first groove 34, and separated from the second protrusion 32 by a second groove 35. In addition, the distance between the top surface of the ridge 33 and the bottom surface of the flat plate portion 30 (i.e., the maximum material thickness of the region of the waveguide layer 103 where the ridge 33 is located) is greater than the distance between the top surfaces of the first and second protrusions 31, 32 and the bottom surface of the flat plate portion 30 (i.e., the maximum material thickness of the region of the waveguide layer 103 where the first and second protrusions 31, 32 are located). In this way, the first groove 34 and the second groove 35 can prevent the diffusion of the optical mode field in the second direction, thereby allowing light to propagate more concentratedly in the region where the ridge 33 is located. Therefore, the design scheme of the embodiment of the present disclosure can enhance the waveguide layer 103's ability to limit and guide light transmission, thereby improving device performance.

[0034] In the disclosed embodiments, the optical modulation module 100 is not limited to a specific product type and may be, for example, an electro-optic modulation module or a thermo-optic modulation module. Electro-optic modulation modules utilize the electro-optic effect of waveguide materials to phase modulate transmitted light, and offer relatively high modulation speeds. Thermo-optic modulation modules utilize the thermo-optic effect of waveguide materials to phase modulate transmitted light, and offer relatively low modulation speeds, but have the advantages of a wide phase modulation range and high modulation efficiency.

[0035] As shown in FIG2 , in some embodiments of the present disclosure, in addition to the waveguide layer 103, the optical modulation module 100 further includes a substrate 101, an isolation layer 102, and a cover layer 104. The substrate 101, isolation layer 102, waveguide layer 103, and cover layer 104 are sequentially arranged, with the waveguide layer 103 formed on the isolation layer 102. The refractive index of the material of the isolation layer 102 and the cover layer 104 is lower than that of the waveguide layer 103. The isolation layer 102 and the cover layer 104 have lower refractive indices than the waveguide layer 103, thereby confining light transmission primarily within the waveguide layer 103, thereby leveraging the aforementioned advantages of the ridge waveguide.

[0036] As shown in FIG3 , in some embodiments, the cover layer 104 covers the ridge 33, the first groove 34, and the second groove 35, and also covers at least a portion of the first protrusion 31 and at least a portion of the second protrusion 32. In this way, the electrode layer 105 can be disposed on the cover layer 104, and the design and arrangement height of the electrodes in the electrode layer 105 can be flexibly adjusted by adjusting the coverage area and thickness of the cover layer 104 to maximize the matching of electrical transmission speed and optical transmission speed. As shown in FIG3 , according to some embodiments of the present disclosure, the optical modulation module 100 further includes an electrode layer 105 formed on the surface of the cover layer 104.

[0037] In other embodiments of the present disclosure, the cover layer 104 may only cover the ridge 33, the first groove 34, and the second groove 35, and the electrode layer 105 may be directly formed on the surface of the waveguide layer 103. As shown in FIG4 , according to some embodiments of the present disclosure, the optical modulation module 100 further includes an electrode layer 105 formed on a surface of at least one of the first protrusion 31 and the second protrusion 32.

[0038] As shown in Figure 5A, in some embodiments of the present disclosure, a first groove 34 is formed between the ridge 33 and the first protrusion 31, and a second groove 35 is formed between the ridge 33 and the second protrusion 32, wherein the width W of the first groove 34 and the second groove 35 gradually decreases along the first direction.

[0039] As shown in Figure 5B, in some embodiments of the present disclosure, a first groove 34 is formed between the ridge 33 and the first protrusion 31, and a second groove 35 is formed between the ridge 33 and the second protrusion 32, wherein the width W of the first groove 34 and the second groove 35 gradually increases along the first direction.

[0040] As shown in Figure 5C, in some embodiments of the present disclosure, a first groove 34 is formed between the ridge 33 and the first protrusion 31, and a second groove 35 is formed between the ridge 33 and the second protrusion 32, wherein along the first direction, the depth H of the first groove 34 and the second groove 35 gradually decreases and the width also gradually decreases until the groove disappears.

[0041] As shown in Figure 5D, in some embodiments of the present disclosure, a first groove 34 is formed between the ridge 33 and the first protrusion 31, and a second groove 35 is formed between the ridge 33 and the second protrusion 32, wherein the depth and width of the first groove 34 and the second groove 35 gradually increase from zero along the first direction.

[0042] In some embodiments of the present disclosure, as shown in FIG5A , the lengths of the first grooves 34 and the second grooves 35 along the first direction may be less than the length of the ridge 33 along the first direction. In other embodiments of the present disclosure, the lengths of the first grooves and the second grooves along the first direction may be equal to the length of the ridge along the first direction, that is, the first grooves and the second grooves penetrate the waveguide layer along the first direction.

[0043] In the above-described embodiment, the variation trend of the depth and / or width of the first groove 34 and the second groove 35 can be determined according to the light transmission direction and the specific type of photonic device optically coupled to the optical modulation module 100. A gradual design of the depth and / or width of the first groove 34 and the second groove 35 can moderately hinder the diffusion of the optical mode field in the second direction, thereby enabling the optical modulation module 100 to achieve gentle and smooth modulation of the mode spot, thereby reducing light transmission loss.

[0044] The present disclosure also provides an optical modulator, including the optical modulation module 100 according to any of the aforementioned embodiments. The optical modulator may be, for example, a thermo-optical modulator or an electro-optical modulator. The electro-optical modulator may be, for example, a Mach-Zehnder modulator. In addition to the optical modulation module 100, the optical modulator may further include a light splitting element, a light combining element, and the like.

[0045] Based on the above design of the optical modulation module 100 and the beneficial effects obtained, the device performance of the optical modulator is correspondingly improved, the optical transmission loss is small, and the modulation efficiency is higher.

[0046] It should be understood that in this specification, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships or dimensions based on the orientations or positional relationships or dimensions shown in the accompanying drawings, and these terms are used only for the convenience of description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present disclosure.

[0047] Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first," "second," or "third" may explicitly or implicitly include one or more of the features. Throughout the present disclosure, "plurality" means two or more, unless otherwise specifically defined.

[0048] In this disclosure, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections, electrical connections, or communication; direct connections or indirect connections through an intermediate medium; and internal connections between two components or interactions between two components. Those skilled in the art will understand the specific meanings of these terms in this disclosure based on specific circumstances.

[0049] In the present disclosure, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature includes the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0050] This specification provides many different embodiments or examples that can be used to implement the present disclosure. It should be understood that these different embodiments or examples are purely exemplary and are not intended to limit the scope of protection of the present disclosure in any way. Those skilled in the art can conceive of various changes or replacements based on the disclosure of the specification of the present disclosure, all of which should be included within the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on the scope of protection defined by the appended claims.

Claims

1. An optical modulation module, comprising a waveguide layer, wherein the waveguide layer comprises: Flat plate department; A first protruding portion and a second protruding portion are located on the flat plate portion and extend along a first direction, and a distance between a top surface of the first protruding portion and a top surface of the second protruding portion and a bottom surface of the flat plate portion is H1; as well as A ridge portion is located above the flat plate portion and extends along the first direction and is located between the first protruding portion and the second protruding portion, a first groove is formed between the ridge portion and the first protruding portion, a second groove is formed between the ridge portion and the second protruding portion, and the distance between the top surface of the ridge portion and the bottom surface of the flat plate portion is H2, wherein H2>H1.

2. The optical modulation module according to claim 1, wherein: Along a first direction, the depths of the first groove and the second groove gradually decrease, and / or the widths of the first groove and the second groove gradually decrease.

3. The optical modulation module according to claim 1, wherein: Along a first direction, the depths of the first groove and the second groove gradually increase, and / or the widths of the first groove and the second groove gradually increase.

4. The optical modulation module according to claim 1, wherein: The lengths of the first groove and the second groove along the first direction are equal to or smaller than the length of the ridge convex portion along the first direction.

5. The optical modulation module according to claim 1, further comprising: substrate; an isolation layer located on the substrate, wherein the waveguide layer is formed on the isolation layer; and A covering layer covering the waveguide layer, wherein the material refractive index of the isolation layer and the covering layer is smaller than the material refractive index of the waveguide layer.

6. The optical modulation module according to claim 5, wherein: The cover layer covers the ridge convex portion, the first groove, and the second groove.

7. The optical modulation module according to claim 6, wherein: The covering layer also covers at least a portion of the first protrusion and at least a portion of the second protrusion.

8. The optical modulation module according to any one of claims 1 to 7, further comprising: an electrode layer formed on a surface of the covering layer; or An electrode layer is formed on a surface of at least one of the first protrusion and the second protrusion.

9. The optical modulation module according to any one of claims 1 to 7, wherein: The optical modulation module includes an electro-optical modulation module or a thermo-optical modulation module. 10 . An optical modulator, comprising the optical modulation module according to claim 1 .

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