Two-dimensional grating coupler

Abstract

The disclosure provides a two-dimensional grating coupler, and relates to the fields of optoelectronic integration and optical communication technology. The two-dimensional grating coupler comprises a silicon waveguide layer configured to receive an optical signal, and to couple the optical signal according to a first optical field coupling coefficient and a second optical field coupling coefficient to obtain a first coupled optical signal and a second coupled optical signal, and to output the first coupled optical signal and the second coupled optical signal along a first direction and a second direction, respectively; a first organic electro-optic material layer arranged above the silicon waveguide layer and having a first electrode pair arranged therein; and a second organic electro-optic material layer arranged below the silicon waveguide layer and having a second electrode pair arranged therein. According to the embodiment of the disclosure, the organic electro-optic material is bonded to the upper layer and the lower layer of the silicon waveguide layer, and the electrode pairs that can be independently driven are arranged in each direction, so that the real-time adjustment of the optical field coupling coefficient is realized, and the coupling efficiency is significantly improved.

Description

Technical Field

[0001] This disclosure relates to the fields of optoelectronic integration and optical communication technology, and in particular to a two-dimensional grating coupler. Background Technology

[0002] Integrated silicon-based photonics systems, with their high bandwidth, low crosstalk, and compatibility with CMOS processes, have become the core platform in the field of high-speed optical interconnects. Grating couplers, as key on-chip optical input / output interfaces, are widely used in chip-level optoelectronic system testing and signal transmission due to their advantages such as small size and planar coupling.

[0003] However, traditional silicon-based grating couplers face two major bottlenecks: one is the mode field mismatch problem, where the Gaussian mode field of a single-mode fiber is difficult to match with the diffraction field of the grating, resulting in a significant reduction in coupling efficiency. Existing solutions involve customizing gratings for fibers with different core diameters. These static gratings require high manufacturing precision, have complex fabrication processes, and once fabricated, cannot dynamically compensate for temperature drift, manufacturing deviations, or changes in fiber mode dimensions.

[0004] Secondly, there is polarization sensitivity. One-dimensional grating couplers can only efficiently couple a single polarization state (such as the TE mode), and the coupling efficiency for orthogonal polarization states (TM modes) drops sharply. Summary of the Invention

[0005] In view of the above problems, embodiments of this disclosure provide a two-dimensional grating coupler to solve the problems of polarization sensitivity and low efficiency of existing grating couplers.

[0006] One aspect of this disclosure provides a two-dimensional grating coupler, characterized in that it comprises:

[0007] A silicon waveguide layer is used to receive optical signals and couple them according to a first optical field coupling coefficient and a second optical field coupling coefficient to obtain a first coupled optical signal and a second coupled optical signal, respectively. The first coupled optical signal and the second coupled optical signal are then output along a first direction and a second direction, respectively. The backward extensions of the first direction and the second direction are perpendicular to each other. A first organic electro-optic material layer is disposed above the silicon waveguide layer. Multiple first electrodes are disposed on both sides of the first organic electro-optic material layer parallel to the first direction. Any first electrode on one side is combined with a first electrode on the other side to form a first electrode pair. The first electrode pair is used to adjust the first optical field coupling coefficient. A second organic electro-optic material layer is disposed below the silicon waveguide layer. Multiple second electrodes are disposed on both sides of the second organic electro-optic material layer parallel to the second direction. Any second electrode on one side is combined with a second electrode on the other side to form a second electrode pair. The second electrode pair is used to adjust the second optical field coupling coefficient.

[0008] According to embodiments of this disclosure, the spacing between a plurality of first electrodes on the same side is the same; the spacing between a plurality of second electrodes on the same side is the same.

[0009] According to embodiments of this disclosure, the first organic electro-optic material layer includes a plurality of first organic electro-optic rectangular structures, and the width of the first organic electro-optic rectangular structure is less than or equal to the width of the first electrode; the second organic electro-optic material layer includes a plurality of second organic electro-optic rectangular structures, and the width of the second organic electro-optic rectangular structure is less than or equal to the width of the second electrode.

[0010] According to an embodiment of this disclosure, a silicon waveguide layer includes: an output waveguide, a transition waveguide, and a two-dimensional grating. The two-dimensional grating is in contact with a plurality of first organic electro-optic rectangular structures and a plurality of second organic electro-optic rectangular structures. The short end face of the transition waveguide is connected to the output waveguide, and the long end face of the transition waveguide is connected to the two-dimensional grating. The width of the transition waveguide gradually narrows along the direction from the two-dimensional grating toward the output waveguide.

[0011] According to embodiments of this disclosure, the width, height, grating period, and duty cycle of the two-dimensional grating are the same in different directions, and the shape of the two-dimensional grating includes circular and square.

[0012] According to embodiments of this disclosure, a first organic electro-optic rectangular structure is located above the unetched portion of the two-dimensional grating, filling along a second direction and periodically arranged along a first direction; a second organic electro-optic rectangular structure is located below the unetched portion of the two-dimensional grating, filling along the first direction and periodically arranged along the second direction.

[0013] According to embodiments of this disclosure, the two-dimensional grating coupler further includes: a first reflective layer disposed above a first organic electro-optic material layer, the first reflective layer being used to couple optical signals to a silicon waveguide layer and to reflect a portion of the optical signals reflected from the silicon waveguide layer to the top of the silicon waveguide layer back to the silicon waveguide layer.

[0014] According to embodiments of this disclosure, the two-dimensional grating coupler further includes: a coupling optical fiber disposed above the first reflective layer, the coupling optical fiber being used to transmit optical signals to the silicon waveguide layer.

[0015] According to embodiments of this disclosure, the two-dimensional grating coupler further includes a protective layer disposed over the first reflective layer, the first organic electro-optic material layer, and the silicon waveguide layer.

[0016] According to an embodiment of this disclosure, the two-dimensional grating coupler further includes: a second reflective layer disposed below the second organic electro-optic material layer, the second reflective layer being used to reflect back a portion of the optical signal reflected from the silicon waveguide layer to the area below the silicon waveguide layer back to the silicon waveguide layer.

[0017] The embodiments of this disclosure bond organic electro-optic materials to the upper and lower layers of the silicon waveguide layer respectively, and arrange independently drivable electrode pairs in each direction. The device of this disclosure can adjust the optical field coupling coefficient in real time during device operation, achieve precise matching of the two-dimensional profile of the diffracted optical field, and significantly improve coupling efficiency without replacing the device or re-etching. Attached Figure Description

[0018] The foregoing contents, as well as other objects, features, and advantages of this disclosure, will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0019] Figure 1 A schematic diagram of the grating coupling portion structure according to an embodiment of the present disclosure is shown.

[0020] Figure 2 A schematic diagram illustrating the structure of a first organic electro-optic material layer according to an embodiment of the present disclosure is shown.

[0021] Figure 3 A schematic diagram illustrating the structure of a second organic electro-optic material layer according to an embodiment of the present disclosure is shown.

[0022] Figure 4 A schematic diagram of a silicon waveguide layer according to an embodiment of the present disclosure is shown.

[0023] Figure 5 A schematic diagram of a two-dimensional grating coupler according to an embodiment of the present disclosure is shown.

[0024] [Explanation of Labels in the Attached Image]

[0025] 1-First organic electro-optic material layer; 101-First electrode; 102-First organic electro-optic rectangular structure; 2-Silicon waveguide layer; 201-Output waveguide; 202-Transition waveguide; 203 Two-dimensional grating; 3-Second organic electro-optic material layer; 301-Second electrode; 302-Second organic electro-optic rectangular structure; 4-First reflective layer; 5-Coupled optical fiber; 6-Second reflective layer; 7-Protective layer; 8-Substrate. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0027] It should be noted that similar or identical parts are referred to by the same reference numerals in the accompanying drawings or description. The technical features of the various embodiments exemplified in the specification can be freely combined to form new solutions without conflict. Furthermore, each claim can stand alone as an embodiment, or the technical features in the various claims can be combined to form new embodiments. In the drawings, the shape or thickness of the embodiments may be enlarged and indicated in a simplified or convenient manner. Moreover, elements or implementations not shown or described in the drawings are those known to those skilled in the art. Additionally, although this document provides examples of parameters containing specific values, it should be understood that the parameters need not be exactly equal to the corresponding values, but can approximate the corresponding values ​​within acceptable error tolerances or design constraints.

[0028] Unless there are technical obstacles or contradictions, the various embodiments described above in this disclosure can be freely combined to form other embodiments, all of which are within the protection scope of this disclosure.

[0029] Although this disclosure has been described in conjunction with the accompanying drawings, the embodiments disclosed in the drawings are intended to illustrate preferred embodiments of this disclosure and should not be construed as limiting the disclosure. The dimensions in the drawings are merely illustrative and should not be construed as limiting the disclosure.

[0030] While some embodiments of the general concept of this disclosure have been shown and described, those skilled in the art will understand that changes may be made to these embodiments without departing from the principles and spirit of the general concept of this disclosure, the scope of which is defined by the claims and their equivalents.

[0031] Figure 1 A schematic diagram of the grating coupling portion structure according to an embodiment of the present disclosure is shown.

[0032] like Figure 1As shown, an embodiment of this disclosure provides a two-dimensional grating coupler, characterized in that it includes: a silicon waveguide layer 2, used to receive optical signals and couple the optical signals according to a first optical field coupling coefficient and a second optical field coupling coefficient to obtain a first coupled optical signal and a second coupled optical signal, and then output the first coupled optical signal and the second coupled optical signal along a first direction and a second direction respectively, wherein the reverse extensions of the first direction and the second direction are perpendicular to each other; a first organic electro-optic material layer 1, disposed above the silicon waveguide layer, wherein multiple first electrodes 101 are disposed on both sides of the first organic electro-optic material layer parallel to the first direction, wherein any one of the first electrodes 101 on one side and one of the first electrodes 101 on the other side are combined to form a first electrode pair, and the first electrode pair is used to adjust the first optical field coupling coefficient; and a second organic electro-optic material layer 3, disposed below the silicon waveguide layer, wherein multiple second electrodes 301 are disposed on both sides of the second organic electro-optic material layer parallel to the second direction, wherein any one of the second electrodes 301 on one side and one of the second electrodes 301 on the other side are combined to form a second electrode pair, and the second electrode pair is used to adjust the second optical field coupling coefficient.

[0033] In some embodiments, both the first organic electro-optic material layer 1 and the second organic electro-optic material layer 3 are organic electro-optic materials with side-chain / host-guest systems, such as PMMA+DR1, PMMA+YLD124, PMMA+DLD164, and PVT copolymers. Other organic electro-optic materials, such as HLD1 / HLD2 materials, can also be used, but the embodiments disclosed herein are not limited to these. The thicknesses of the first organic electro-optic material layer 1 and the second organic electro-optic material layer 3 can be 0.1 μm to 2 μm.

[0034] Organic electro-optic materials have excellent electro-optic properties. In order to utilize the maximum electro-optic coefficient r33 of organic electro-optic materials, the r33 direction of the organic electro-optic materials in the first organic electro-optic material layer 1 is in the same direction as the second direction, and the r33 direction of the organic electro-optic materials in the second organic electro-optic material layer 3 is in the same direction as the first direction.

[0035] The organic electro-optic materials selected in the embodiments of this disclosure are side-chain / host-guest systems, which can be integrated in standard CMOS processes by spin coating or bonding, and can be seamlessly integrated with metal interconnects, electrode fabrication and other steps in silicon photonics platforms, thereby reducing overall manufacturing costs.

[0036] Figure 2 A schematic diagram of the structure of a first organic electro-optic material layer according to an embodiment of the present disclosure is shown. Figure 3 A schematic diagram illustrating the structure of a second organic electro-optic material layer according to an embodiment of the present disclosure is shown.

[0037] In some embodiments, such as Figure 2 and Figure 3As shown, the x-axis direction marked in the figure is taken as the first direction, and the y-axis direction marked in the figure is taken as the second direction. The spacing between multiple first electrodes on the same side is the same; the spacing between multiple second electrodes on the same side is also the same.

[0038] The length, width, and position of the first electrode 101 and the second electrode 301 can be flexibly designed according to the structure of the two-dimensional grating 203. The spacing between multiple first electrodes 101 and multiple second electrodes 301 should be minimized without affecting light absorption to improve modulation efficiency. The number of first electrode pairs and second electrode pairs should at least ensure that the entire length and width of the two-dimensional grating 203 are covered.

[0039] Please continue reading. Figure 2 and Figure 3 In some embodiments, the first organic electro-optic material layer 1 includes a plurality of first organic electro-optic rectangular structures 102, and the width of the first organic electro-optic rectangular structure 102 is less than or equal to the width of the first electrode 101; the second organic electro-optic material layer 3 includes a plurality of second organic electro-optic rectangular structures 302, and the width of the second organic electro-optic rectangular structure 302 is less than or equal to the width of the second electrode 301.

[0040] In some embodiments, the first organic electro-optic rectangular structure 102 is above the unetched portion of the two-dimensional grating 203, fills along the second direction and is periodically arranged along the first direction; the second organic electro-optic rectangular structure 302 is below the unetched portion of the two-dimensional grating 203, fills along the first direction and is periodically arranged along the second direction.

[0041] Figure 4 A schematic diagram of a silicon waveguide layer according to an embodiment of the present disclosure is shown.

[0042] According to embodiments of this disclosure, such as Figure 4 As shown, the x-axis direction marked in the figure is taken as the first direction, and the y-axis direction marked in the figure is taken as the second direction. The silicon waveguide layer in this embodiment includes: an output waveguide 201, a transition waveguide 202, and a two-dimensional grating 203. The two-dimensional grating 203 is in contact with a plurality of first organic electro-optic rectangular structures 102 and a plurality of second organic electro-optic rectangular structures 302. The short end face of the transition waveguide 202 is connected to the output waveguide 201, and the long end face of the transition waveguide 202 is connected to the two-dimensional grating 203. The width of the transition waveguide 202 gradually narrows along the direction from the two-dimensional grating 203 to the output waveguide 201.

[0043] In some embodiments of this disclosure, the shapes of the transition waveguide 202 and the output waveguide 201 are not limited, and those skilled in the art can make corresponding adjustments to obtain the required device dimensions.

[0044] In some embodiments, the two-dimensional grating 203 has the same width, height, grating period, and duty cycle in different directions, and the shape of the two-dimensional grating 203 includes circular and square shapes. The duty cycle of the two-dimensional grating 203 can range from 0.3 to 0.7, and the etching depth of the two-dimensional grating 203 ranges from 20% to 100% of the total thickness of the silicon waveguide layer 2, wherein the thickness of the silicon waveguide layer 2 can be 0.1 μm to 1 μm, and the width of the two-dimensional grating 203 can be 1.5 μm to 15 μm. The grating period of the two-dimensional grating 203 can range from 0.5 μm to 1.5 μm.

[0045] Figure 5 A schematic diagram of a two-dimensional grating coupler according to an embodiment of the present disclosure is shown.

[0046] In some embodiments, such as Figure 5 As shown, the two-dimensional grating coupler in this embodiment further includes: a first reflective layer 4 disposed above the first organic electro-optic material layer 1. The first reflective layer 4 is used to couple optical signals to the silicon waveguide layer 2 and to reflect a portion of the optical signals reflected from the silicon waveguide layer 2 to the top of the silicon waveguide layer 2 back to the silicon waveguide layer 2.

[0047] In some embodiments, the first reflective layer 4 may include two reflective layers. The number of reflective layers mentioned above is only an example, and it should be ensured that the number of reflective layers in the first reflective layer is greater than or equal to two.

[0048] According to an embodiment of this disclosure, the two-dimensional grating coupler in this application embodiment further includes: a coupling optical fiber 5, disposed above the first reflective layer 4, the coupling optical fiber 5 being used to transmit optical signals to the silicon waveguide layer 2.

[0049] Please continue reading. Figure 5 In some embodiments, the coupling fiber 5 is disposed above the first reflective layer 4, and the projection of the incident direction of the coupling fiber 5 into the plane containing the first direction and the second direction is located in the second quadrant.

[0050] In this embodiment, the voltage adjustment device can determine the fiber mode field distribution based on the size and position of the coupled fiber 5, thereby determining the voltage between the two first electrodes 101 of the first organic electro-optic material layer 1 and the target voltage between the two second electrodes 301 of the second organic electro-optic material layer 3. Adjusting the voltage between the two first electrodes 101 of the first organic electro-optic material layer 1 and the voltage between the two second electrodes 301 of the second organic electro-optic material layer 3 allows the first electrodes 101 and the second electrodes 301 to change the effective refractive index of the two-dimensional grating 203 through the electro-optic effect, thereby changing the coupling coefficient of the diffracted light field of the two-dimensional grating 203.

[0051] The voltages of the two first electrodes 101 of the first organic electro-optic material layer 1 and the two second electrodes 301 of the second organic electro-optic material layer 3 can be dynamically adjusted according to the diameter, tilt angle and position of the coupling fiber 5. This allows for adjustment of the refractive indices of the first organic electro-optic rectangular structure 102 and the second organic electro-optic rectangular structure 302, thereby changing the refractive indices of the two-dimensional grating 203 along the first and second directions. This, in turn, adjusts the coupling coefficient of the diffraction light field of the two-dimensional grating 203 along the first and second directions, making its diffraction mode field distribution match the mode field of the coupling fiber 5 as closely as possible, thus improving the coupling efficiency of the grating coupler.

[0052] Specifically, when the diameter, tilt angle, and position of the coupling fiber 5 change, the coupling coefficients of the first and second parts of the coupling grating 5 can be adjusted by redistributing the voltages of the first electrode pair of the first organic electro-optic material layer 1 and the second electrode pair of the second organic electro-optic material layer 3, thereby improving the coupling efficiency. In practical applications, the voltage adjustment mechanism can sequentially adjust the voltage applied between the first electrode pair and the voltage applied between the second electrode pair according to the actual position and tilt angle of the coupling fiber 5, while simultaneously measuring the intensity of the light output from the fiber. When the coupled light is strongest, the voltages applied between the first and second electrode pairs at this point are the target voltages.

[0053] In one possible embodiment, the coupling grating 5 can also be a non-uniform grating, that is, the width, height, grating period and duty cycle of the coupling grating 5 can be different along different directions.

[0054] Please continue reading. Figure 5 According to an embodiment of the present disclosure, the two-dimensional grating coupler further includes a protective layer 7, which is disposed over the first reflective layer 4, the first organic electro-optic material layer 1, and the silicon waveguide layer 2.

[0055] Please continue reading. Figure 5 The two-dimensional grating coupler in this embodiment further includes: a second reflective layer 6 disposed below the second organic electro-optic material layer 3. The second reflective layer 6 is used to reflect back a portion of the optical signal reflected from the silicon waveguide layer 2 to the area below the silicon waveguide layer 2 back to the silicon waveguide layer 2.

[0056] In some embodiments, the second reflective layer 6 is disposed on the surface of the substrate 8, and the second reflective layer 6 may be a metal reflector or a distributed Bragg reflector.

[0057] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process may be rearranged without departing from the scope of this disclosure. The appended method claims provide elements of various steps in an exemplary order and are not intended to limit the scope to a specific order or hierarchy.

[0058] It should also be noted that the directional terms mentioned in the embodiments, such as "up," "down," "front," "back," "left," and "right," are only for reference to the directions in the accompanying drawings and are not intended to limit the scope of protection of this disclosure. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or constructions will be omitted when they may cause confusion in understanding this disclosure. Furthermore, the shapes, sizes, and positional relationships of the components in the drawings do not reflect their actual size, scale, or actual positional relationships.

[0059] In the detailed description above, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, this disclosure is in a state of having fewer features than all of the features of the single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, with each claim representing a separate preferred embodiment of this disclosure.

[0060] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this disclosure, "a plurality of" means at least two, such as two, three, etc., unless otherwise expressly specified. The term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," as "including" is used as a conjunction in the claims. The use of any term "or" in the specification or claims is intended to mean "non-exclusive or."

[0061] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A two-dimensional grating coupler, characterized by, The application relates to a two-dimensional grating coupler. The two-dimensional grating coupler comprises: a silicon waveguide layer for receiving an optical signal and coupling the optical signal according to a first optical field coupling coefficient and a second optical field coupling coefficient to obtain a first coupled optical signal and a second coupled optical signal, and outputting the first coupled optical signal and the second coupled optical signal along a first direction and a second direction respectively, wherein the first direction is perpendicular to the reverse extension line of the second direction; a first organic electro-optical material layer arranged above the silicon waveguide layer, two sides of the first organic electro-optical material layer parallel to the first direction are provided with a plurality of first electrodes, any one of the first electrodes on one side of the two sides is connected with one of the first electrodes on the other side to form a first electrode pair, and the first electrode pair is used for adjusting the first optical field coupling coefficient; 2. The two-dimensional grating coupler of claim 1, wherein, a second organic electro-optical material layer arranged below the silicon waveguide layer, two sides of the second organic electro-optical material layer parallel to the second direction are provided with a plurality of second electrodes, any one of the second electrodes on one side of the two sides is connected with one of the second electrodes on the other side to form a second electrode pair, and the second electrode pair is used for adjusting the second optical field coupling coefficient. The intervals between the first electrodes on the same side are the same.

3. The two-dimensional grating coupler of claim 1, wherein, The intervals between the second electrodes on the same side are the same. The first organic electro-optical material layer comprises a plurality of first organic electro-optical rectangular structures, and the width of the first organic electro-optical rectangular structure is less than or equal to the width of the first electrode.

4. The two-dimensional grating coupler of claim 3, wherein, The second organic electro-optical material layer comprises a plurality of second organic electro-optical rectangular structures, and the width of the second organic electro-optical rectangular structure is less than or equal to the width of the second electrode. The silicon waveguide layer comprises an output waveguide, a transition waveguide and a two-dimensional grating, the two-dimensional grating is in contact with the plurality of first organic electro-optical rectangular structures and the plurality of second organic electro-optical rectangular structures.

5. The two-dimensional grating coupler of claim 4, wherein, The short end face of the transition waveguide is connected with the output waveguide, the long end face of the transition waveguide is connected with the two-dimensional grating, and the width of the transition waveguide gradually narrows in the direction from the two-dimensional grating to the output waveguide.

6. The two-dimensional grating coupler of claim 4, wherein, The width, height, grating period and duty cycle of the two-dimensional grating in different directions are the same, and the shape of the two-dimensional grating comprises a circle and a square. The first organic electro-optical rectangular structure is arranged above the unetched part of the two-dimensional grating, is filled along the second direction and is periodically arranged along the first direction.

7. The two-dimensional grating coupler of claim 1, wherein, The second organic electro-optical rectangular structure is arranged below the unetched part of the two-dimensional grating, is filled along the first direction and is periodically arranged along the second direction. The two-dimensional grating coupler further comprises:

8. The two-dimensional grating coupler of claim 7, wherein, a first reflective layer arranged above the first organic electro-optical material layer, the first reflective layer is used for coupling the optical signal to the silicon waveguide layer and re-reflecting the part of the optical signal reflected from the silicon waveguide layer to the upper side of the silicon waveguide layer back to the silicon waveguide layer. The two-dimensional grating coupler further comprises:

9. The two-dimensional grating coupler of claim 7, wherein, a coupling optical fiber arranged above the first reflective layer, the coupling optical fiber is used for transmitting the optical signal to the silicon waveguide layer. The two-dimensional grating coupler further comprises: A protective layer is disposed above the first reflective layer, the first organic electro-optical material layer, and the silicon waveguide layer.

10. The two-dimensional grating coupler of claim 1, wherein, The two-dimensional grating coupler further includes: A second reflective layer is disposed below the second organic electro-optical material layer, and the second reflective layer is configured to re-reflect the portion of the optical signal reflected by the silicon waveguide layer to below the silicon waveguide layer back to the silicon waveguide layer.

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