An end-face coupler based on a multi-layer waveguide material structure and a preparation method thereof

Abstract

The present invention relates to an end-face coupler based on a multilayer waveguide material structure and its preparation method. The present invention comprises a substrate layer, a buried oxide layer, a first waveguide layer, a first isolation layer, a second waveguide layer, a second isolation layer, a third waveguide layer, and an upper cladding layer, arranged sequentially from bottom to top. The first waveguide layer comprises two input S-shaped waveguides and one output waveguide. The input S-shaped waveguide is composed of an input tapered waveguide, an input straight waveguide, an S-shaped curved waveguide, an input straight waveguide, and an output tapered waveguide connected in sequence. The output waveguide is composed of an input tapered waveguide, an input straight waveguide, and an output tapered waveguide connected in sequence. The waveguide structure of the third waveguide layer is identical to that of the first waveguide layer, with corresponding waveguide structures in the two layers aligned vertically. The second waveguide layer comprises an output waveguide composed of an input tapered waveguide and an output straight waveguide connected in sequence. The present invention can couple optical fibers or lasers with nanowire waveguides, increasing alignment tolerance and improving coupling efficiency.

Description

Technical Field

[0001] The present invention relates to an end face coupler based on a multi-layer waveguide material structure and a preparation method thereof, belonging to the technical field of semiconductor preparation. Background Art

[0002] With the rapid development of optical communications and the internet, data transmission and processing speeds are accelerating, and silicon photonics technology has become a key solution for high-speed optical communication devices and systems. Because silicon photonics devices are compatible with existing standard CMOS processes, they can be integrated with microelectronic integrated circuits to achieve high-performance, low-cost, compact, and highly integrated on-chip optical interconnects. Consequently, SOI-based silicon-based optoelectronic devices have become a research hotspot.

[0003] The key part of silicon-based photonic chip packaging technology is to achieve the coupling connection between the optical signal inside the chip and the external optical signal (mostly optical fiber). The core diameter of a single-mode optical fiber is about 8 to 10 microns, and the cross-sectional size of the silicon photonic chip waveguide is less than 1 micron. The difference in size between the two is large, and the coupling loss of the two when directly coupled is large, resulting in large coupling losses, which makes it difficult to use in practical applications. Therefore, it is necessary to design special couplers at the input / output ends of the chip to improve the coupling efficiency. There are two types of couplers: end-face coupling and vertical grating coupling. Due to the disadvantages of low coupling efficiency and inconvenience in packaging of grating couplers, they are mostly used in the design and testing of silicon photonic chips. End-face coupling has the characteristics of simple packaging process and high coupling efficiency and has been widely used.

[0004] End-face coupling uses a spot converter to directly align the waveguide cross-section of the chip's input / output ports with the cross-section of the optical fiber, matching the mode field of the single-mode fiber with the mode field of the silicon waveguide for optimal coupling efficiency. Conventional planar waveguide chip coupling uses a fiber array (FA) to align the chip's end-face waveguides. A single adhesive is used at the coupling end faces of the chip and fiber array, achieving both refractive index matching and strong bonding.

[0005] Therefore, it is of great significance to design a silicon-based coupler using reasonable materials, which has simple packaging process, high coupling efficiency with ordinary single-mode optical fiber and laser, and large alignment tolerance. Summary of the Invention

[0006] The technical problem to be solved by the present invention is: the present invention provides an end face coupler based on a multilayer waveguide material structure and a preparation method thereof, so as to solve the problem of low coupling efficiency between silicon-based photonic chips and optical fibers and lasers in the prior art, and improve the coupling efficiency and coupling tolerance of silicon waveguide couplers.

[0007] The technical solution of the present invention is as follows: In a first aspect, the present invention provides an end coupler based on a multilayer waveguide material structure, comprising an upper cladding layer 1, a substrate layer 2, a buried oxide layer 3, a first waveguide layer 4, a first isolation layer 5, a second waveguide layer 6, a second isolation layer 7, and a third waveguide layer 8;

[0008] The buried oxide layer 3 is placed on the substrate layer 2, the first waveguide layer 4 is placed on the buried oxide layer 3, the first isolation layer 5 is placed on the first waveguide layer 4, the second waveguide layer 6 is placed on the first isolation layer 5, the second isolation layer 7 is placed on the second waveguide layer 6, and the third waveguide layer 8 is placed on the second isolation layer 7; the first waveguide layer 4, the second waveguide layer 6 and the third waveguide layer 8 are arranged in the same direction; the first waveguide layer 4 is composed of two input S-shaped waveguides X1 and one output waveguide X2; the input S-shaped waveguide X1 in the first waveguide layer 4 is composed of an input tapered waveguide Y1, an input straight waveguide Y2, an S-shaped curved waveguide Y3, an input straight waveguide Y4 and an output tapered waveguide Y 5 are connected in sequence; the output waveguide X2 in the first waveguide layer 4 is composed of an input tapered waveguide H1, an input straight waveguide H2, and an output tapered waveguide H3 connected in sequence; the tips of the input tapered waveguide Y1 and the input tapered waveguide H1 face leftward, and the tips of the output tapered waveguide Y5 and the output tapered waveguide H3 face rightward; the waveguide structure in the third waveguide layer 8 is the same as that in the first waveguide layer 4, and the corresponding waveguide structures in the two layers are vertically aligned; the second waveguide layer 6 is an intermediate waveguide layer containing an output waveguide X3, which is composed of an input tapered waveguide Z1 and an output straight waveguide Z2 connected in sequence; the upper cladding layer 1 is placed on the third waveguide layer 8.

[0009] As a further solution of the present invention, the waveguide material of the first waveguide layer 4 , the second waveguide layer 6 and the third waveguide layer 8 is silicon-based waveguide Si, SiN, SiON or α-Si.

[0010] As a further solution of the present invention, the first isolation layer 5 and the second isolation layer 7 are both made of silicon dioxide.

[0011] As a further solution of the present invention, the two leftmost waveguide structures of the first waveguide layer 4 and the third waveguide layer 8 are identical and symmetrical, and the output ends of the two input S-shaped waveguides X1 of the first waveguide layer 4 and the third waveguide layer 8 and the output waveguide X2 form a directional coupler structure with a three-waveguide structure in the horizontal plane.

[0012] As a further solution of the present invention, the distance between the two input tapered waveguides Y1 on the left side of the first waveguide layer 4 or the third waveguide layer 8 is between 0.5-5 μm.

[0013] As a further solution of the present invention, each output waveguide X2 in the first waveguide layer 4 and the third waveguide layer 8 and the output waveguide X3 in the second waveguide layer 6 are in the same vertical plane and form a directional coupler structure with three waveguide structures in a vertical direction.

[0014] As a further solution of the present invention, each output waveguide X2 of the first waveguide layer 4 and the third waveguide layer 8 is coupled to the output waveguide X3 in the second waveguide layer 6 by means of DC structure coupling.

[0015] As a further embodiment of the present invention, the coupling of the waveguide with the optical fiber and the laser is achieved in the following manner: the four input tapered waveguides Y1 are coupled to the signal light from the two connected input tapered waveguides Y1 in each layer through a directional coupler having a three-waveguide structure in the horizontal direction. The signal light then passes sequentially through the input straight waveguide Y2, the S-shaped bend waveguide Y3, the input straight waveguide Y4, and the output tapered waveguide Y5, and finally couples into the output waveguide X2. The two output waveguides X2 of the first waveguide layer 4 and the third waveguide layer 8 form a directional coupler having a three-waveguide structure in the vertical direction with the output waveguide X3 of the second waveguide layer 6. Through the directional coupler of the three-waveguide structure in the vertical direction, the signal light of the first waveguide layer 4 and the third waveguide layer 8 enters the output waveguide X3 of the second waveguide layer 6.

[0016] In a second aspect, the present invention further provides a method for preparing an end coupler based on a multi-layer waveguide material structure. When the first waveguide layer is made of single crystal silicon and the second and third waveguide layers are made of α-Si, the specific steps of the method are as follows:

[0017] Step 1: Take an SOI wafer and clean it with a cleaning solvent. After cleaning, perform photolithography, which includes stripping, exposure, development, and drying. Then, dry-etch the pattern, remove the resist, and clean it to form the first waveguide layer 4.

[0018] Step 2, using PECVD technology to deposit a layer of silicon dioxide as the upper cladding layer of the first waveguide layer on the first waveguide layer 4 produced in step 1;

[0019] Step 3, reverse etching is performed on the upper cladding layer of the first waveguide layer produced in Step 2 to form a first isolation layer 5;

[0020] Step 4: Chemically polish the surface of the silicon dioxide layer obtained on the first isolation layer 5 prepared in Step 3 using CMP technology to obtain a smooth surface, and then clean it;

[0021] Step 5: Deposit an α-Si layer on the first isolation layer 5 produced in Step 4 using LPCVD technology, then polish and clean it, and perform photolithography to etch out the second waveguide layer waveguide to form the second waveguide layer 6;

[0022] Step 6: Deposit a layer of silicon dioxide on the second waveguide layer 6 produced in Step 5 using PECVD technology to serve as the upper cladding layer of the second waveguide layer;

[0023] Step 7, reverse etching is performed on the upper cladding layer of the second waveguide layer produced in Step 6 to form a second isolation layer 7;

[0024] Step 8, chemically polishing the surface of the silicon dioxide layer obtained on the second isolation layer 7 prepared in Step 7 using CMP technology to obtain a smooth surface, and then cleaning;

[0025] Step 9: Deposit an α-Si layer on the second isolation layer 7 made in Step 8 using LPCVD technology, then polish and clean it, and perform photolithography to etch out the third waveguide layer waveguide as the third waveguide layer 8;

[0026] Step 10: Deposit a silicon dioxide upper cladding layer on the third waveguide layer 8 obtained in Step 9 to obtain the final structure.

[0027] In a third aspect, the present invention further provides a method for preparing an end coupler based on a multilayer waveguide material structure. When the first, second, and third waveguide layer materials are silicon nitride, the specific steps of the method are as follows:

[0028] Step 1: Take a pure silicon wafer, clean it, and thermally oxidize it to obtain a buried oxide layer 3. Then, chemically polish the obtained surface using CMP technology to obtain a smooth surface.

[0029] Step 2: Deposit a silicon nitride layer on the buried oxide layer 3 formed in Step 1 using LPCVD technology, polish, and then perform photolithography. Photolithography includes spin coating, exposure, development, drying, etching, and finally stripping and cleaning to obtain the first waveguide layer 4.

[0030] Step 3, using PECVD technology to deposit a layer of silicon dioxide on the first waveguide layer 4 produced in Step 2 as the upper cladding layer of the first waveguide layer;

[0031] Step 4, reverse etching is performed on the upper cladding layer of the first waveguide layer produced in Step 3 to form a first isolation layer 5;

[0032] Step 5: Chemically polish the surface of the silicon dioxide layer obtained on the first isolation layer 5 prepared in Step 4 using CMP technology to obtain a smooth surface, and then clean it;

[0033] Step 6: Deposit a silicon nitride layer on the first isolation layer 5 formed in Step 5 using LPCVD technology, polish, and then perform photolithography. Photolithography includes spinning, exposure, development, drying, etching, and finally stripping and cleaning to obtain a second waveguide layer 6.

[0034] Step 7: Deposit a layer of silicon dioxide on the second waveguide layer 6 produced in Step 6 using PECVD technology to serve as the upper cladding layer of the second waveguide layer;

[0035] Step 8, reverse etching is performed on the upper cladding layer of the first waveguide layer produced in Step 7 to form a second isolation layer 7;

[0036] Step 9: Chemically polish the surface of the silicon dioxide layer obtained on the second isolation layer 7 prepared in Step 8 using CMP technology to obtain a smooth surface, and then clean it;

[0037] Step 10: Deposit a silicon nitride layer on the second isolation layer 7 formed in Step 9 using LPCVD technology, polish, and then perform photolithography. Photolithography includes spin coating, exposure, development, drying, etching, and finally stripping and cleaning to obtain a third waveguide layer 8.

[0038] Step 11: Deposit a silicon dioxide upper cladding layer on the third waveguide layer 8 obtained in Step 10 to obtain a final structure.

[0039] The present invention utilizes a three-layer waveguide structure, each with a transmission waveguide structure and a coupling waveguide structure. This structure offers high reliability, compatibility with CMOS technology, and scalability. The simplified packaging allows for direct and efficient coupling of end couplers with optical fibers and lasers, improving optical coupling efficiency, increasing alignment tolerance, and facilitating large-scale optical integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings, which are incorporated into and constitute a part of the specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention. In the drawings, similar reference numerals are used to represent similar elements. The drawings described below are some embodiments of the present invention, but not all. It is clear that those skilled in the art can derive other drawings from these drawings without inventive effort.

[0041] Figure 1 This is a schematic structural diagram of an end coupler based on a multi-layer waveguide material structure according to the present invention.

[0042] Figures 2 to 12FIG2 shows a method for preparing an end coupler based on a multilayer waveguide material structure in Example 1. To clearly illustrate the waveguide structure, the upper cladding layer is omitted.

[0043] Figure 2 This is a side view of the intermediate structure obtained in step 1 in embodiment 1 of the present invention.

[0044] Figure 3 This is a top view schematic diagram of the intermediate structure obtained in step 1 in embodiment 1 of the present invention.

[0045] Figure 4 This is a schematic diagram of the end face of the intermediate structure obtained in step 1 in embodiment 1 of the present invention.

[0046] Figure 5 This is a schematic diagram of the intermediate structure obtained in step 3 in embodiment 1 of the present invention.

[0047] Figure 6 This is a side view of the intermediate structure obtained in step 5 of Example 1 of the present invention.

[0048] Figure 7 This is a top view schematic diagram of the intermediate structure obtained in step 5 in Example 1 of the present invention.

[0049] Figure 8 This is a schematic diagram of the end face of the intermediate structure obtained in step 5 of Example 1 of the present invention.

[0050] Figure 9 This is a schematic diagram of the intermediate structure obtained in step 7 in embodiment 1 of the present invention.

[0051] Figure 10 This is a side view of the intermediate structure obtained in step 9 in embodiment 1 of the present invention.

[0052] Figure 11 This is a top view schematic diagram of the intermediate structure obtained in step 9 in embodiment 1 of the present invention.

[0053] Figure 12 This is a schematic diagram of the end face of the intermediate structure obtained in step 9 in embodiment 1 of the present invention.

[0054] Figure 13 This is the specific structure of the top surface of the first waveguide layer and the third waveguide layer of the present invention.

[0055] Figure 14 This is the specific structure of the top surface of the second waveguide layer of the present invention.

[0056] Figure 1-14Reference numerals in the figure: 1-upper cladding layer, 2-substrate layer, 3-buried oxide layer, 4-first waveguide layer, 5-first isolation layer, 6-second waveguide layer, 7-second isolation layer, 8-third waveguide layer, X1-input S-shaped waveguide (Y1-input tapered waveguide, Y2-input straight waveguide, Y3-S-shaped bent waveguide, Y4-input straight waveguide, Y5-output tapered waveguide), X2-output waveguide (H1-input tapered waveguide, H2-input straight waveguide, H3-output tapered waveguide), X3-output waveguide (Z1-input tapered waveguide, Z2-output straight waveguide). DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other in any way.

[0058] The end coupler based on the multi-layer waveguide material structure and the manufacturing method thereof provided by the present invention are described in detail below with reference to the accompanying drawings.

[0059] Example 1: Figures 1-14 As shown, in the first aspect, the present invention provides an end coupler based on a multi-layer waveguide material structure, comprising an upper cladding layer 1, a substrate layer 2, a buried oxide layer 3, a first waveguide layer 4, a first isolation layer 5, a second waveguide layer 6, a second isolation layer 7, and a third waveguide layer 8;

[0060] The buried oxide layer 3 is placed on the substrate layer 2, the first waveguide layer 4 is placed on the buried oxide layer 3, the first isolation layer 5 is placed on the first waveguide layer 4, the second waveguide layer 6 is placed on the first isolation layer 5, the second isolation layer 7 is placed on the second waveguide layer 6, and the third waveguide layer 8 is placed on the second isolation layer 7; the first waveguide layer 4, the second waveguide layer 6 and the third waveguide layer 8 are arranged in the same direction; the first waveguide layer 4 is composed of two input S-shaped waveguides X1 and one output waveguide X2; the input S-shaped waveguide X1 in the first waveguide layer 4 is composed of an input tapered waveguide Y1, an input straight waveguide Y2, an S-shaped curved waveguide Y3, an input straight waveguide Y4 and an output tapered waveguide Y 5 are connected in sequence; the output waveguide X2 in the first waveguide layer 4 is composed of an input tapered waveguide H1, an input straight waveguide H2, and an output tapered waveguide H3 connected in sequence; the tips of the input tapered waveguide Y1 and the input tapered waveguide H1 face leftward, and the tips of the output tapered waveguide Y5 and the output tapered waveguide H3 face rightward; the waveguide structure in the third waveguide layer 8 is the same as that in the first waveguide layer 4, and the corresponding waveguide structures in the two layers are vertically aligned; the second waveguide layer 6 is an intermediate waveguide layer containing an output waveguide X3, which is composed of an input tapered waveguide Z1 and an output straight waveguide Z2 connected in sequence; the upper cladding layer 1 is placed on the third waveguide layer 8.

[0061] As a further solution of the present invention, the waveguide material of the first waveguide layer 4 , the second waveguide layer 6 and the third waveguide layer 8 is silicon-based waveguide Si, SiN, SiON or α-Si.

[0062] As a further solution of the present invention, the first isolation layer 5 and the second isolation layer 7 are both made of silicon dioxide.

[0063] As a further solution of the present invention, the two leftmost waveguide structures of the first waveguide layer 4 and the third waveguide layer 8 are identical and symmetrical, and the output ends of the two input S-shaped waveguides X1 of the first waveguide layer 4 and the third waveguide layer 8 and the output waveguide X2 form a directional coupler structure with a three-waveguide structure in the horizontal plane.

[0064] As a further solution of the present invention, the distance between the two input tapered waveguides Y1 on the left side of the first waveguide layer 4 or the third waveguide layer 8 is between 0.5-5 μm.

[0065] As a further solution of the present invention, each output waveguide X2 in the first waveguide layer 4 and the third waveguide layer 8 and the output waveguide X3 in the second waveguide layer 6 are in the same vertical plane and form a directional coupler structure with three waveguide structures in a vertical direction.

[0066] As a further solution of the present invention, each output waveguide X2 of the first waveguide layer 4 and the third waveguide layer 8 is coupled to the output waveguide X3 in the second waveguide layer 6 by means of DC structure coupling.

[0067] As a further embodiment of the present invention, the coupling of the waveguide with the optical fiber and the laser is achieved in the following manner: the four input tapered waveguides Y1 are coupled to the signal light from the two connected input tapered waveguides Y1 in each layer through a directional coupler having a three-waveguide structure in the horizontal direction. The signal light then passes sequentially through the input straight waveguide Y2, the S-shaped bend waveguide Y3, the input straight waveguide Y4, and the output tapered waveguide Y5, and finally couples into the output waveguide X2. The two output waveguides X2 of the first waveguide layer 4 and the third waveguide layer 8 form a directional coupler having a three-waveguide structure in the vertical direction with the output waveguide X3 of the second waveguide layer 6. Through the directional coupler of the three-waveguide structure in the vertical direction, the signal light of the first waveguide layer 4 and the third waveguide layer 8 enters the output waveguide X3 of the second waveguide layer 6.

[0068] The working principle of the present invention is as follows: the present invention is applied to the coupling of nanowire waveguides and optical fibers or lasers. The optical signal from the optical fiber or laser is first coupled through the four input tapered waveguides Y1 on the left end into the four nanowire waveguides in the upper and lower layers (two in each layer, for a total of four, as shown in the figure). A directional coupler with a three-waveguide structure in each horizontal layer couples the signal light from the two input tapered waveguides Y1 in that layer, sequentially passing through the input straight waveguide Y2, the S-shaped bend waveguide Y3, the input straight waveguide Y4, and the output tapered waveguide Y5, before finally coupling into the output waveguide X2. The upper and lower output waveguides and the middle waveguide form a vertical three-waveguide directional coupler. Through this vertical three-waveguide directional coupler, the signal light from the upper and lower layers enters the middle output waveguide. This process effectively allows the input optical signal to enter the middle waveguide via the four input tapered waveguides and two-stage directional couplers.

[0069] In a second aspect, this embodiment further provides a method for preparing an end coupler based on a multi-layer waveguide material structure as described in the first aspect. When the material of the first waveguide layer is single crystal silicon, and the materials of the second and third waveguide layers are α-Si, the specific steps of the method are as follows:

[0070] Step 1: Take an SOI wafer and clean it with a cleaning solvent. After cleaning, perform photolithography, which includes stripping, exposure, development, and drying. Then, dry-etch the pattern, remove the resist, and clean it to form the first waveguide layer 4.

[0071] Step 2, using PECVD technology to deposit a layer of silicon dioxide as the upper cladding layer of the first waveguide layer on the first waveguide layer 4 produced in step 1;

[0072] Step 3, reverse etching is performed on the upper cladding layer of the first waveguide layer produced in Step 2 to form a first isolation layer 5;

[0073] Step 4: Chemically polish the surface of the silicon dioxide layer obtained on the first isolation layer 5 prepared in Step 3 using CMP technology to obtain a smooth surface, and then clean it;

[0074] Step 5: Deposit an α-Si layer on the first isolation layer 5 produced in Step 4 using LPCVD technology, then polish and clean it, and perform photolithography to etch out the second waveguide layer waveguide to form the second waveguide layer 6;

[0075] Step 6: Deposit a layer of silicon dioxide on the second waveguide layer 6 produced in Step 5 using PECVD technology to serve as the upper cladding layer of the second waveguide layer;

[0076] Step 7, reverse etching is performed on the upper cladding layer of the second waveguide layer produced in Step 6 to form a second isolation layer 7;

[0077] Step 8, chemically polishing the surface of the silicon dioxide layer obtained on the second isolation layer 7 prepared in Step 7 using CMP technology to obtain a smooth surface, and then cleaning;

[0078] Step 9: Deposit an α-Si layer on the second isolation layer 7 made in Step 8 using LPCVD technology, then polish and clean it, and perform photolithography to etch out the third waveguide layer waveguide as the third waveguide layer 8;

[0079] Step 10: Deposit a silicon dioxide upper cladding layer on the third waveguide layer 8 obtained in Step 9 to obtain the final structure.

[0080] Example 2: This example further provides a method for preparing an end coupler based on a multilayer waveguide material structure as described in the first aspect. The structure of the end coupler based on a multilayer waveguide material structure in this example is the same as that in Example 1, except that the first, second, and third waveguide layers are made of silicon nitride. The specific steps of the method are as follows:

[0081] Step 1: Take a pure silicon wafer, clean it, and thermally oxidize it to obtain a buried oxide layer 3. Then, chemically polish the obtained surface using CMP technology to obtain a smooth surface.

[0082] Step 2: Deposit a silicon nitride layer on the buried oxide layer 3 formed in Step 1 using LPCVD technology, polish, and then perform photolithography. Photolithography includes spin coating, exposure, development, drying, etching, and finally stripping and cleaning to obtain the first waveguide layer 4.

[0083] Step 3, using PECVD technology to deposit a layer of silicon dioxide on the first waveguide layer 4 produced in Step 2 as the upper cladding layer of the first waveguide layer;

[0084] Step 4, reverse etching is performed on the upper cladding layer of the first waveguide layer produced in Step 3 to form a first isolation layer 5;

[0085] Step 5: Chemically polish the surface of the silicon dioxide layer obtained on the first isolation layer 5 prepared in Step 4 using CMP technology to obtain a smooth surface, and then clean it;

[0086] Step 6: Deposit a silicon nitride layer on the first isolation layer 5 formed in Step 5 using LPCVD technology, polish, and then perform photolithography. Photolithography includes spinning, exposure, development, drying, etching, and finally stripping and cleaning to obtain a second waveguide layer 6.

[0087] Step 7: Deposit a layer of silicon dioxide on the second waveguide layer 6 produced in Step 6 using PECVD technology to serve as the upper cladding layer of the second waveguide layer;

[0088] Step 8, reverse etching is performed on the upper cladding layer of the first waveguide layer produced in Step 7 to form a second isolation layer 7;

[0089] Step 9: Chemically polish the surface of the silicon dioxide layer obtained on the second isolation layer 7 prepared in Step 8 using CMP technology to obtain a smooth surface, and then clean it;

[0090] Step 10: Deposit a silicon nitride layer on the second isolation layer 7 formed in Step 9 using LPCVD technology, polish, and then perform photolithography. Photolithography includes spin coating, exposure, development, drying, etching, and finally stripping and cleaning to obtain a third waveguide layer 8.

[0091] Step 11: Deposit a silicon dioxide upper cladding layer on the third waveguide layer 8 obtained in Step 10 to obtain a final structure.

[0092] The contents described above can be implemented individually or in combination in various ways, and these variations are all within the protection scope of the present invention.

[0093] It should be noted that, in the present invention, relational terms such as first and second, etc., are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprises" or any other variant thereof is intended to cover non-exclusive inclusion, so that an article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such article or device. In the absence of further limitations, the elements defined by the phrase "comprises..." do not exclude the presence of other identical elements in the article or device comprising the elements.

[0094] The above embodiments are intended to illustrate the technical solutions of the present invention and are not intended to limit the present invention. The present invention is described in detail with reference to the preferred embodiments only. It should be understood by those skilled in the art that the technical solutions of the present invention may be modified or replaced with equivalents without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications and replacements should be included within the scope of the claims of the present invention.

Claims

1. An end coupler based on a multilayer waveguide material structure, characterized in that: include: Upper cladding layer (1), substrate layer (2), buried oxide layer (3), first waveguide layer (4), first isolation layer (5), second waveguide layer (6), second isolation layer (7), and third waveguide layer (8); The buried oxide layer (3) is placed on the substrate layer (2), the first waveguide layer (4) is placed on the buried oxide layer (3), the first isolation layer (5) is placed on the first waveguide layer (4), the second waveguide layer (6) is placed on the first isolation layer (5), the second isolation layer (7) is placed on the second waveguide layer (6), and the third waveguide layer (8) is placed on the second isolation layer (7); the first waveguide layer (4), the second waveguide layer (6) and the third waveguide layer (8) are arranged in the same direction; the first waveguide layer (4) comprises two input S-shaped waveguides X1 and one output waveguide X2; the input S-shaped waveguide X1 in the first waveguide layer (4) is composed of an input tapered waveguide Y1, an input straight waveguide Y2, an S-shaped curved waveguide Y3, an input straight waveguide The output waveguide X2 in the first waveguide layer (4) is composed of an input tapered waveguide H1, an input straight waveguide H2 and an output tapered waveguide H3 connected in sequence; the tips of the input tapered waveguide Y1 and the input tapered waveguide H1 face left, and the tips of the output tapered waveguide Y5 and the output tapered waveguide H3 face right; the waveguide structure in the third waveguide layer (8) is the same as the waveguide structure in the first waveguide layer (4), and the corresponding waveguide structures in the two layers are aligned in the vertical direction; the second waveguide layer (6) is an intermediate waveguide layer containing an output waveguide X3, which is composed of an input tapered waveguide Z1 and an output straight waveguide Z2 connected in sequence; the upper cladding layer (1) is placed on the third waveguide layer (8); The leftmost two waveguide structures of the first waveguide layer (4) and the third waveguide layer (8) are identical and symmetrical, and the output ends of the two input S-shaped waveguides X1 of the first waveguide layer (4) and the third waveguide layer (8) and the output waveguide X2 form a directional coupler structure with a three-waveguide structure in a horizontal plane; The output waveguides X2 in the first waveguide layer (4) and the third waveguide layer (8) are in the same vertical plane as the output waveguide X3 in the second waveguide layer (6) to form a directional coupler structure with three waveguides in a vertical direction.

2. The end coupler based on a multilayer waveguide material structure according to claim 1, characterized in that: The waveguide materials of the first waveguide layer (4), the second waveguide layer (6) and the third waveguide layer (8) are silicon-based waveguide Si, SiN, SiON or α-Si.

3. The end coupler based on a multilayer waveguide material structure according to claim 1, characterized in that: The first isolation layer (5) and the second isolation layer (7) are both made of silicon dioxide.

4. The end coupler based on a multilayer waveguide material structure according to claim 1, characterized in that: The distance between the two input tapered waveguides Y1 on the left side of the first waveguide layer (4) or the third waveguide layer (8) is between 0.5 and 5 μm.

5. The end coupler based on a multilayer waveguide material structure according to claim 1, characterized in that: The output waveguides X2 of the first waveguide layer (4) and the third waveguide layer (8) are coupled to the output waveguide X3 in the second waveguide layer (6) by means of a DC structure.

6. The end coupler based on a multilayer waveguide material structure according to claim 1, characterized in that: The coupling of the waveguide with the optical fiber and the laser is achieved in the following manner: the four input tapered waveguides Y1 are coupled to the signal light of the two connected input tapered waveguides Y1 in this layer through the directional coupler of the three-waveguide structure in the horizontal direction of each layer, and the signal light passes through the input straight waveguide Y2, the S-shaped bending waveguide Y3, the input straight waveguide Y4, and the output tapered waveguide Y5 in sequence, and finally couples into the output waveguide X2; the two layers of output waveguides X2 of the first waveguide layer (4) and the third waveguide layer (8) and the output waveguide X3 of the second waveguide layer (6) form a directional coupler of the three-waveguide structure in the vertical direction; through the directional coupler of the three-waveguide structure in the vertical direction, the signal light of the two layers of the first waveguide layer (4) and the third waveguide layer (8) will enter the output waveguide X3 of the second waveguide layer (6).

7. A method for preparing an end coupler based on a multilayer waveguide material structure, characterized in that: When the material of the first waveguide layer is single crystal silicon, and the materials of the second and third waveguide layers are α-Si, the specific steps of the method are as follows: Step 1, take an SOI wafer, clean it with a cleaning solvent, and then perform photolithography after cleaning, wherein the photolithography includes stripping, exposure, development, and drying, and then dry etching, stripping, and cleaning the pattern to form the first waveguide layer (4); Step 2, depositing a layer of silicon dioxide as an upper cladding layer of the first waveguide layer by using PECVD technology on the first waveguide layer (4) produced in step 1; Step 3, performing reverse etching on the upper cladding layer of the first waveguide layer produced in Step 2 to form a first isolation layer (5); Step 4, chemically polishing the surface of the silicon dioxide layer obtained on the first isolation layer (5) produced in Step 3 using CMP technology to obtain a smooth surface, and then cleaning; Step 5, depositing an α-Si layer on the first isolation layer (5) produced in Step 4 using LPCVD technology, then polishing and cleaning, performing photolithography, and etching a second waveguide layer waveguide as the second waveguide layer (6); Step 6, using PECVD technology to deposit a layer of silicon dioxide on the second waveguide layer (6) produced in step 5 as an upper cladding layer of the second waveguide layer; Step 7, performing reverse etching on the upper cladding layer of the second waveguide layer produced in Step 6 to form a second isolation layer (7); Step 8, chemically polishing the surface of the silicon dioxide layer obtained on the second isolation layer (7) produced in Step 7 using CMP technology to obtain a smooth surface, and then cleaning; Step 9, depositing an α-Si layer on the second isolation layer (7) produced in Step 8 using LPCVD technology, then polishing and cleaning, performing photolithography, and etching a third waveguide layer waveguide as the third waveguide layer (8); Step 10: Deposit a silicon dioxide upper cladding layer on the third waveguide layer (8) obtained in Step 9 to obtain the final structure.

8. A method for preparing an end coupler based on a multilayer waveguide material structure, characterized in that: When the material of the first, second and third waveguide layers is silicon nitride, the specific steps of the method are as follows: Step 1: Take a pure silicon wafer, clean it, and obtain a buried oxide layer (3) after thermal oxidation. Use CMP technology to chemically polish the obtained surface to obtain a smooth surface; Step 2, depositing a silicon nitride layer on the buried oxide layer (3) produced in step 1 using LPCVD technology, polishing, and then performing photolithography, which includes spin coating, exposure, development, drying, etching, and finally debonding and cleaning to obtain a first waveguide layer (4); Step 3, using PECVD technology to deposit a layer of silicon dioxide on the first waveguide layer (4) produced in step 2 as an upper cladding layer of the first waveguide layer; Step 4, reverse etching is performed on the upper cladding layer of the first waveguide layer produced in Step 3 to form a first isolation layer (5); Step 5, chemically polishing the surface of the silicon dioxide layer obtained on the first isolation layer (5) produced in Step 4 using CMP technology to obtain a smooth surface, and then cleaning; Step 6, depositing a silicon nitride layer on the first isolation layer (5) produced in Step 5 using LPCVD technology, polishing, and then performing photolithography, which includes spinning, exposure, development, drying, etching, and finally desizing and cleaning to obtain a second waveguide layer (6); Step 7, using PECVD technology to deposit a layer of silicon dioxide on the second waveguide layer (6) produced in step 6 as an upper cladding layer of the second waveguide layer; Step 8, reverse etching is performed on the upper cladding layer of the first waveguide layer produced in Step 7 to form a second isolation layer (7); Step 9, chemically polishing the surface of the silicon dioxide layer obtained on the second isolation layer (7) produced in Step 8 using CMP technology to obtain a smooth surface, and then cleaning; Step 10, depositing a silicon nitride layer on the second isolation layer (7) produced in Step 9 using LPCVD technology, polishing, and then performing photolithography, which includes spin coating, exposure, development, drying, etching, and finally debonding and cleaning to obtain a third waveguide layer (8); Step 11, depositing a silicon dioxide upper cladding layer on the third waveguide layer (8) obtained in Step 10 to obtain the final structure.

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