Multi-port input and multi-port output polymer waveguide optical power divider based on MMI structure and preparation method thereof

Abstract

The invention discloses a multi-port input and multi-port output polymer waveguide optical power divider based on an MMI structure and a preparation method thereof, and belongs to the technical field of planar optical waveguide devices and preparation thereof. The optical fiber is composed of a silicon wafer substrate, a polymer lower cladding layer, a polymer optical waveguide core layer and a polymer upper cladding layer from bottom to top, the polymer optical waveguide core layer and the polymer upper cladding layer are jointly located on the polymer lower cladding layer, and the polymer optical waveguide core layer is completely wrapped in the polymer upper cladding layer. The refractive index of the material of the polymer optical waveguide core layer is higher than that of the polymer upper and lower cladding layers; the whole polymer optical waveguide core layer is based on an MMI optical waveguide structure. According to the waveguide type power divider, the characteristics of large process tolerance and small size of an MMI optical waveguide structure are combined, the advantage of various types of organic polymer materials is utilized, the purpose of carrying out same power distribution on input of multiple different ports is achieved, large-scale batch production can be achieved, and the waveguide type power divider can be applied to practice.

Description

Technical Field

[0001] The present invention belongs to the technical field of planar optical waveguide devices and preparation thereof, and in particular relates to a polymer waveguide optical power distributor based on an MMI structure with multi-port input and multi-port output and a preparation method thereof. Background Art

[0002] In recent years, with the rapid development of information technology, people have put forward higher requirements on the communication capacity, transmission rate and reliability of optical communication systems. As the core device of optical communication systems and on-chip optical interconnect integrated chips, optical power dividers evenly distribute the input optical signal power to several output ports, thereby realizing the distribution and synthesis of optical signals. They are the basic components of optical switches, optical modulators, multiplexers and demultiplexers. Among them, the optical power divider based on planar optical waveguide structure is used to divide an input signal into multiple output signals to meet specific application requirements. It is not only well compatible with optical fibers, but also has the advantages of compact structure, tunability, low insertion loss and flexible design.

[0003] In the existing technical field, we find that the optical power divider structures proposed so far generally present a single-ended input form, such as the common 1×3, 1×6, 1×N and other structures. These traditional optical power dividers have certain limitations in the design of the input port and have not achieved a fundamental breakthrough for a long time. This situation has, to a certain extent, limited the application of optical power dividers in more complex network environments.

[0004] However, with the continuous development of science and technology and the continuous improvement of the performance requirements of equipment in actual application scenarios. In order to effectively improve the flexibility of the port network to better adapt to the diversified network layout and realize the key function of multi-port input and multi-port output, the present invention proposes a new optical power divider, which has the characteristics of multi-port input and multi-port output, bringing new ways for the development of related fields such as optical communication, and is expected to solve the shortcomings of traditional optical power dividers in complex application scenarios. Summary of the invention

[0005] In order to overcome the shortcomings of traditional optical power dividers, the object of the present invention is to provide a polymer waveguide optical power divider based on an MMI structure with multi-port input and multi-port output and a preparation method thereof.

[0006] The present invention uses silicon as the waveguide substrate, organic polymer materials as the upper and lower claddings of the optical waveguide, and the core layer of the polymer optical waveguide uses organic polymer materials with different refractive indices. This design makes full use of the diversity, flexible processing performance and low cost advantages of existing polymer materials, and the preparation process is simple, compatible with semiconductor processes, easy to integrate, and suitable for large-scale production. Therefore, the invention has important application value in the field of optical communications and planar optical waveguide power dividers.

[0007] The technical solution adopted by the present invention to solve the technical problem is as follows:

[0008] A polymer waveguide optical power divider based on MMI structure with multi-port input and multi-port output, which is composed of a silicon wafer substrate 20, a polymer lower cladding 21, a polymer optical waveguide core layer 22' and a polymer upper cladding 23 from bottom to top, wherein the polymer optical waveguide core layer 22' and the polymer upper cladding 23 are located on the polymer lower cladding 21, and the polymer optical waveguide core layer 22' is completely covered in the polymer upper cladding 23; the entire polymer optical waveguide core layer 22' is based on the MMI optical waveguide structure, as shown in the attached figure. Figure 1 As shown, from left to right along the propagation direction of light, it is composed of a first input straight waveguide 1, a second input straight waveguide 2 and a third input straight waveguide 3 having the same structure and size and being parallel to each other, a first S-bent waveguide 4 and a second S-bent waveguide 6 having the same structure and size, a first parallel straight waveguide 5, a first input tapered waveguide 7, a second input tapered waveguide 8 and a third input tapered waveguide 9 having the same structure and size, a multimode interference waveguide 10, a first output tapered waveguide 11, a second output tapered waveguide 12 and a third output tapered waveguide 13 having the same structure and size, a third S-bent waveguide 14 and a fourth S-bent waveguide 16 having the same structure and size, a second parallel straight waveguide 15, a first output straight waveguide 17, a second output straight waveguide 18 and a third output straight waveguide 19 having the same structure and size and being parallel to each other; the first input tapered waveguide 7, the second input tapered waveguide 8 and the third input tapered waveguide 9 having the same structure and size, The first input straight waveguide 1, the first S-bent waveguide 4 and the first input tapered waveguide 7 are connected in sequence, the second input straight waveguide 2, the first parallel straight waveguide 5 and the second input tapered waveguide 8 are connected in sequence, the third input straight waveguide 3, the second S-bent waveguide 6 and the third input tapered waveguide 9 are connected in sequence; the first output tapered waveguide 11, the third S-bent waveguide 14 and the first output straight waveguide 17 are connected in sequence, the second output tapered waveguide 12, the second parallel straight waveguide 15 and the second output straight waveguide 18 are connected in sequence, and the third output tapered waveguide 13, the fourth S-bent waveguide 16 and the third output straight waveguide 19 are connected in sequence.

[0009] The widths of the first input straight waveguide 1, the second input straight waveguide 2, the third input straight waveguide 3, the first S-bend waveguide 4, the first parallel straight waveguide 5, the second S-bend waveguide 6, the third S-bend waveguide 14, the second parallel straight waveguide 15, the fourth S-bend waveguide 16, the first output straight waveguide 17, the second output straight waveguide 18 and the third output straight waveguide 19 are equal, that is, W1=4-6μm; the widths of the input ends of the first output tapered waveguide 11, the second output tapered waveguide 12 and the third output tapered waveguide 13 are equal, that is, W1=4-6μm. The widths of the output ends of the second output tapered waveguide 12 and the third output tapered waveguide 13 are equal, namely, W1=4-6 μm; the lengths of the first input straight waveguide 1, the second input straight waveguide 2, and the third input straight waveguide 3 are equal, namely, L1=500-3000 μm; the projected lengths of the first S-bend waveguide 4 and the second S-bend waveguide 6 along the first parallel straight waveguide 5 are equal, namely, L2=800-2500 μm, and the length of the first parallel straight waveguide 5 is L2=800-2500 μm; the lengths of the first input tapered waveguide 7, the second input tapered waveguide 8, and the third input tapered waveguide 9 are equal, namely, L2=800-2500 μm. = L3 = 50-200 μm; the widths of the first input tapered waveguide 7, the second input tapered waveguide 8 and the third input tapered waveguide 9 at the connection with the multimode interference waveguide 10 are equal to W2 = 5-6 μm, and W2>W1; the width W3 of the multimode interference waveguide 10 is 20-30 μm, and the length L4 is 1500-2000 μm; the width W4 at the connection with the second output tapered waveguide 12 is 5-6 μm, and the width of the multimode interference waveguide 10 at the connection with the first output tapered waveguide 11 and the third output tapered waveguide 13 is equal to W5 = 5~15μm, and W5>W4; the lengths of the first output tapered waveguide 11, the second output tapered waveguide 12 and the third output tapered waveguide 13 are equal to L5=50~200μm; the projection lengths of the third S-bend waveguide 14 and the fourth S-bend waveguide 16 along the second parallel straight waveguide 15 are equal to L6=800~2000μm, and the length of the second parallel straight waveguide 15 is L6=800~2000μm; the lengths of the first output straight waveguide 17, the second output straight waveguide 18 and the third output straight waveguide 19 are equal to L7=500~2000μm.

[0010] As attached Figure 2 As shown, Figure 1Schematic diagram of cross section at AA' in the figure; from bottom to top, it is composed of a silicon wafer substrate 20, a polymer lower cladding 21 prepared on the silicon wafer substrate 20, a polymer optical waveguide core layer 22' with a strip structure prepared on the polymer lower cladding 21, and a polymer upper cladding 23 prepared on the polymer optical waveguide core layer 22' and the polymer lower cladding 21; the polymer optical waveguide core layer 22' is embedded in the polymer upper cladding 23; at this time, the polymer optical waveguide core layer 22' includes three parts: a first S-bend waveguide 4, a first parallel straight waveguide 5 and a second S-bend waveguide 6.

[0011] The signal light can be input from the first input straight waveguide 1, the second input straight waveguide 2 or the third input straight waveguide 3 respectively, and then enter the first input tapered waveguide 7, the second input tapered waveguide 8 or the third input tapered waveguide 9 through the first S-bent waveguide 4, the first parallel straight waveguide 5 or the second S-bent waveguide 6, and then enter the multimode interference waveguide 10 to excite multiple modes. Due to the structure and material properties of the multimode waveguide, at a specific transmission distance, the signal light will be recombined into a field distribution similar to the input light field. The light is evenly divided into three paths and enters the first output tapered waveguide 11, the second output tapered waveguide 12 and the third output tapered waveguide 13, and then passes through the third S-bent waveguide 14, the second parallel straight waveguide 15 and the fourth S-bent waveguide 16 respectively, and finally output from the first output straight waveguide 17, the second output straight waveguide 18 and the third output straight waveguide 19.

[0012] The thickness of the silicon wafer substrate 20 is 0.5-1 mm, the thickness of the polymer lower cladding layer 21 is 3-15 μm, the thickness of the polymer optical waveguide core layer 22 ′ is 2-10 μm, and the thickness of the polymer upper cladding layer 23 on the polymer optical waveguide core layer 22 ′ is 3-15 μm.

[0013] The present invention discloses a method for preparing a polymer waveguide optical power divider based on an MMI structure with multi-port input and multi-port output. The manufacturing process is shown in the attached Figure 3 , the specific steps are as follows:

[0014] A: Cleaning of silicon wafer substrate

[0015] Wipe the silicon wafer substrate 20 vigorously with a cotton ball soaked in acetone, and wipe it repeatedly for 2 to 3 times; then wipe the silicon wafer substrate 20 vigorously with a cotton ball soaked in ethanol, and wipe it repeatedly for 2 to 3 times; after wiping it clean, rinse it repeatedly with deionized water, and finally blow dry the silicon wafer with nitrogen, and then put it in a clean culture dish and seal it for storage;

[0016] B: Preparation of the lower cladding of polymer optical waveguide

[0017] The polymer lower cladding material (the polymer lower cladding material is a series of organic polymer materials with good transparency including polycarbonate (PC), polyimide (PI), polymethyl methacrylate (PMMA), polyethylene (PE), polyester (PET), polystyrene (PS), EpoClad, etc.) is spin-coated on the cleaned silicon wafer substrate 20 by a spin coating process, the spin coating speed is 1000-5000 rpm, and after the spin coating is completed, it is baked at 100° C.-150° C. for 3-60 minutes (after the baking of special materials such as EpoClad, it is necessary to first bake at 110-130° C. for 1-10 minutes, expose the whole for 5-30 seconds, and then bake at 130-150° C. for 2-50 minutes), and the thickness of the obtained polymer lower cladding 21 is 3-15 μm;

[0018] C: Preparation of polymer optical waveguide core layer

[0019] The polymer optical waveguide core layer material (the polymer optical waveguide core layer is a series of wet-etchable ultraviolet negative photoresist materials including EpoCore, SU-8 2002, and SU-8 2005, and the refractive index of the polymer optical waveguide core layer material is higher than the refractive index of the polymer upper and lower cladding layers) is spin-coated on the polymer lower cladding layer 21 to form a polymer optical waveguide core layer film 22, the spin coating speed is 1000-5000 rpm, and the thickness of the prepared polymer optical waveguide core layer film 22 is 2-10 μm; the prepared polymer optical waveguide core layer film 22 is pre-baked, that is, baked at 50° C.-180° C. for 3-30 minutes, and naturally cooled to room temperature after baking; the polymer optical waveguide core layer film 22 is subjected to plate-to-plate photolithography, the ultraviolet light wavelength emitted by the photolithography machine is 350-400 nm, and the waveguide mask is complementary to the structure of the polymer optical waveguide core layer 22' to be prepared (such as Figure 1 As shown), when the photolithography plate is in close contact with the silicon wafer substrate, exposure is performed for 4 to 40 seconds, so that the polymer optical waveguide core layer film 22 in the polymer optical waveguide core layer 22' structure to be prepared is exposed to ultraviolet light; the silicon wafer substrate after photolithography is removed from the photolithography machine for intermediate baking, that is, baking at 50°C to 180°C for 5 to 30 minutes, and naturally cooling to room temperature after baking; the polymer optical waveguide core layer 22' structure is developed, that is, first wet etching in a developer corresponding to the polymer optical waveguide core layer material 10 to 60 seconds, remove the unexposed polymer optical waveguide core layer film 22, leaving only the polymer optical waveguide core layer 22' structure corresponding to the mask, then use isopropyl alcohol solution to wash away the developer and the polymer optical waveguide core layer material remaining on the surface of the silicon wafer, then rinse the isopropyl alcohol remaining on the surface with deionized water and blow dry with nitrogen; finally, bake at 120° C. to 150° C. for 30 to 60 minutes to post-bake the film, thus completing the preparation of the polymer optical waveguide core layer 22' with a strip structure;

[0020] D: Preparation of the upper cladding layer of polymer optical waveguide

[0021] The polymer upper cladding material is spin-coated on the waveguide core layer 22' and the polymer lower cladding 21 by a spin coating process, and the spin coating speed is 1000 to 5000 rpm. After the spin coating is completed, it is baked at 120°C to 150°C for 3 to 60 minutes. The thickness of the obtained polymer upper cladding 23 is 3 to 15 μm (the thickness of the upper cladding on the polymer optical waveguide core layer), thereby completing the preparation of a polymer waveguide optical power divider based on an MMI structure with multi-port input and multi-port output.

[0022] Compared with the existing device structure and preparation technology, the beneficial effects of the present invention are:

[0023] The waveguide power divider of the present invention combines the characteristics of large process tolerance and small size of the MMI optical waveguide structure, and also utilizes the advantages of a wide variety of organic polymer materials to achieve the purpose of distributing the same power to multiple different port inputs; in addition, the process of preparing the device using polymer materials is relatively simple, requiring only conventional processes such as spin coating and photolithography, and does not require more difficult processes, and has low production cost, high efficiency, and can be mass-produced, so it is a power divider that can be applied in practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 : A schematic diagram of the structure of the multi-port input optical power distributor based on the MMI structure of the present invention;

[0025] Figure 2 : Figure 1 Schematic diagram of the cross section at AA';

[0026] Figure 3 : A flow chart of the preparation process of the optical power distributor with multi-port input according to the present invention;

[0027] Figure 4 (a): A simulation diagram of the light field transmission of the multi-port input optical power divider from the first input straight waveguide 1;

[0028] Figure 4 (b): Simulation diagram of light field transmission when the multi-port input optical power divider is input from the second input straight waveguide 2;

[0029] Figure 4 (c): A simulation diagram of the light field transmission when the multi-port input optical power divider is input from the third input straight waveguide 3;

[0030] Figure 5 (a): The relationship between the normalized output power and the wavelength when the multi-port input optical power distributor is input from the first input straight waveguide 1;

[0031] Figure 5 (b): The relationship between the normalized output power and wavelength of the multi-port input optical power divider when inputting from the second input straight waveguide;

[0032] Figure 5 (c) : The relationship curve of the normalized output power of the multi-port input optical power distributor as a function of wavelength when the input is from the third input straight waveguide 3. DETAILED DESCRIPTION

[0033] Example 1

[0034] like Figure 1 As shown, the multi-port input optical power divider is composed of a first input straight waveguide 1, a second input straight waveguide 2, a third input straight waveguide 3, a first S-bent waveguide 4, a first parallel straight waveguide 5, a second S-bent waveguide 6, a first input tapered waveguide 7, a second input tapered waveguide 8, a third input tapered waveguide 9, a multimode interference waveguide 10, a first output tapered waveguide 11, a second output tapered waveguide 12, a third output tapered waveguide 13, a third S-bent waveguide 14, a second parallel straight waveguide 15, a fourth S-bent waveguide 16, a first output straight waveguide 17, a second output straight waveguide 18, and a third output straight waveguide 19.

[0035] The widths of the first input straight waveguide 1, the second input straight waveguide 2, the third input straight waveguide 3, the first S-bend waveguide 4, the first parallel straight waveguide 5, the second S-bend waveguide 6, the third S-bend waveguide 14, the second parallel straight waveguide 15, the fourth S-bend waveguide 16, the first output straight waveguide 17, the second output straight waveguide 18 and the third output straight waveguide 19 are equal to W1=4μm; the widths of the input ends of the first output tapered waveguide 11, the second output tapered waveguide 12 and the third output tapered waveguide 13 are equal to W1=4μm, The widths of the output ends of the first output tapered waveguide 11, the second output tapered waveguide 12 and the third output tapered waveguide 13 are equal, namely, W1=4 μm; the lengths of the first input straight waveguide 1, the second input straight waveguide 2 and the third input straight waveguide 3 are equal, namely, L1=500 μm; the projected lengths of the first S-bend waveguide 4 and the second S-bend waveguide 6 along the first parallel straight waveguide 5 are equal, namely, L2=1500 μm, and the length of the first parallel straight waveguide 5 is L2=1500 μm; the first input tapered waveguide 7, the second input tapered waveguide 8 and The length of the third input tapered waveguide 9 is equal to L3=60μm; the width of the first input tapered waveguide 7, the second input tapered waveguide 8 and the third input tapered waveguide 9 at the connection with the multimode interference waveguide 10 is equal to W2=6μm; the width W3 of the multimode interference waveguide 10 is 25μm, and the length L4 is 1730μm; the width W4 of the connection between the multimode interference waveguide 10 and the second output tapered waveguide 12 is 5.5μm, and the width W4 of the connection between the multimode interference waveguide 10 and the first output tapered waveguide 11 and the third output tapered waveguide 13 is 5.5μm. The widths of the first output tapered waveguide 11, the second output tapered waveguide 12 and the third output tapered waveguide 13 are equal to L5 = 50 μm; the projection lengths of the third S-bend waveguide 14 and the fourth S-bend waveguide 16 along the second parallel straight waveguide 15 are equal to L6 = 1500 μm, and the length of the second parallel straight waveguide 15 is L6 = 1500 μm; the lengths of the first output straight waveguide 17, the second output straight waveguide 18 and the third output straight waveguide 19 are equal to L7 = 500 μm.

[0036] like Figure 2 As shown, Figure 1 A cross-sectional schematic diagram of a multi-port input optical power divider, wherein the names of the components are: silicon wafer substrate 20, polymer lower cladding layer 21, polymer optical waveguide core layer 22', polymer upper cladding layer 23. The thickness of the silicon wafer substrate 20 is 1 mm, the thickness of the polymer lower cladding layer 21 is 5 μm, the thickness of the polymer optical waveguide core layer 22' is 5 μm, and the thickness of the waveguide upper cladding layer 23 is 5 μm (the thickness of the upper cladding layer above the polymer optical waveguide core layer).

[0037] like Figure 4As shown in (a), the materials and waveguide dimensions used in Example 1 are selected during the simulation process. It can be clearly seen from the simulation diagram that when the input is the fundamental mode at a wavelength of 850nm, the output is the fundamental mode with the same power.

[0038] like Figure 4 As shown in (b), the materials and waveguide dimensions used in Example 1 are selected during the simulation process. It can be clearly seen from the simulation diagram that when the input is the fundamental mode at a wavelength of 850nm, the output is the fundamental mode with the same power.

[0039] Place Figure 4 As shown in (c), the materials and waveguide dimensions used in Example 1 are selected during the simulation process. It can be clearly seen from the simulation diagram that when the input is the fundamental mode at a wavelength of 850nm, the output is the fundamental mode with the same power.

[0040] like Figure 5 As shown in (a), the materials and waveguide dimensions used in Example 1 are selected. It can be seen that in the 800-900nm band, the output power fluctuates slightly with wavelength changes, and the device is not sensitive to wavelength.

[0041] like Figure 5 As shown in (b), the materials and waveguide dimensions used in Example 1 are selected. It can be seen that in the 800-900nm band, the output power fluctuates slightly with wavelength changes, and the device is not sensitive to wavelength.

[0042] like Figure 5 As shown in (c), the materials and waveguide dimensions used in Example 1 are selected. It can be seen that in the 800-900nm band, the output power fluctuates slightly with wavelength changes, and the device is not sensitive to wavelength.

[0043] Example 2

[0044] The preparation method of the optical power distributor with multi-port input based on MMI structure at 850nm of the present invention:

[0045] A: Cleaning of silicon wafer substrate: Wipe the silicon wafer substrate vigorously with a cotton ball soaked in acetone for three times; then wipe the silicon wafer substrate vigorously with a cotton ball soaked in ethanol for three times; after wiping it clean, rinse it repeatedly with deionized water, and finally blow dry the silicon wafer with nitrogen, then put it in a clean culture dish and seal it for storage;

[0046] B: Preparation of polymer optical waveguide lower cladding: The diluted EpoClad polymer lower cladding material was spin-coated on a cleaned silicon wafer substrate using a spin coating process at a speed of 3000 rpm. After spin coating, it was baked at 120°C for 5 minutes, exposed as a whole for 12 seconds, and baked again at 130°C for 30 minutes. The thickness of the obtained polymer lower cladding was 5 μm.

[0047] C: The polymer optical waveguide core layer 22' including the input / output area and the multi-mode interference area of ​​the device is prepared by spin coating, photolithography and wet etching processes: The diluted polymer optical waveguide core layer material EpoCore is spin coated on the polymer lower cladding layer by spin coating process to form a polymer optical waveguide core layer film 22, the spin coating speed is 3000 rpm, and the thickness of the prepared polymer optical waveguide core layer film 22 is 5μm; the prepared polymer optical waveguide core layer film 22 is pre-baked, using a step-by-step heating method, first baked at 50°C for 10 minutes, and then baked at 95°C for 15 minutes, and then cooled after baking; the prepared polymer optical waveguide core layer film 22 is subjected to plate lithography, the ultraviolet light wavelength emitted by the lithography machine is 365nm, and the waveguide mask is the structure of the mode power divider to be prepared (such as Figure 1 As shown in the figure, when the photomask is in close contact with the silicon wafer, photolithography is performed, and the exposure time is 3.5 seconds, so that the polymer optical waveguide core layer area of ​​the device input / output area, the multi-mode interference area, and the tapered waveguide area connecting the multi-mode interference area and the input / output area to be prepared is exposed to ultraviolet light; the silicon wafer after photolithography is taken out of the photolithography machine for intermediate baking, first baked at 50°C for 10 minutes, and then baked at 85°C for 15 minutes. After the baking is completed, the temperature is lowered and the next step is performed after it drops to room temperature; the polymer optical waveguide core layer 22' structure is Perform development, first wet-etch in a developer for 60 seconds to remove the unexposed non-polymer optical waveguide core structure, leaving only the polymer optical waveguide core structure 22' corresponding to the mask, then use an isopropyl alcohol solution to wash away the developer and the polymer optical waveguide core material remaining on the surface of the silicon wafer, then rinse the isopropyl alcohol remaining on the surface with deionized water and blow dry with nitrogen; finally perform post-baking at 130° C. for 40 minutes, thus completing the preparation of the polymer optical waveguide core 22' with a strip structure;

[0048] D: Preparation of polymer optical waveguide upper cladding: The diluted EpoClad polymer upper cladding material was spin-coated on the silicon wafer with the polymer optical waveguide core layer 22' structure prepared by spin coating process, the spin coating speed was 3000 rpm, and after spin coating, it was baked at 120℃ for 5 minutes, the whole was exposed for 12s, and baked again for 3 minutes. The thickness of the polymer upper cladding above the waveguide core layer was 5μm. In this way, the preparation of the MMI structure polymer multi-port input optical power distributor at 850nm was completed.

[0049] It should be pointed out that the specific implementation methods are only representative examples of the present invention. Obviously, the technical solutions of the present invention include but are not limited to the above embodiments, and there may be more forms, such as each power divider can be cascaded as a unit structure to achieve further expansion and application, and the material of the design is not limited to this, and waveguide materials such as silicon, silicon nitride, and lithium niobate can also be used. Those skilled in the art, who are clearly disclosed by the present invention or obtained without objection based on the written description of the document, all belong to the scope of protection of this patent.

Claims

1. A polymer waveguide optical power divider based on MMI structure with multi-port input and multi-port output, characterized in that: From bottom to top, it is composed of a silicon wafer substrate (20), a polymer lower cladding layer (21), a polymer optical waveguide core layer (22') and a polymer upper cladding layer (23); the polymer optical waveguide core layer (22') and the polymer upper cladding layer (23) are located together on the polymer lower cladding layer (21); the polymer optical waveguide core layer (22') is completely covered in the polymer upper cladding layer (23); the refractive index of the polymer optical waveguide core layer (22') material is higher than the refractive index of the polymer lower cladding layer (21) and the polymer upper cladding layer (23); the entire polymer optical waveguide core layer (22') is based on the MMI optical waveguide structure, and from left to right along the propagation direction of light The invention is sequentially composed of a first input straight waveguide (1), a second input straight waveguide (2) and a third input straight waveguide (3) having the same structure and size and being parallel to each other, a first S-bend waveguide (4) and a second S-bend waveguide (6) having the same structure and size, a first parallel straight waveguide (5), a first input tapered waveguide (7), a second input tapered waveguide (8) and a third input tapered waveguide (9) having the same structure and size, a multimode interference waveguide (10), a first output tapered waveguide (11), a second output tapered waveguide (12) and a third output tapered waveguide (13) having the same structure and size, a third S-bend waveguide (14) having the same structure and size, and The invention relates to a fourth S-bend waveguide (16), a second parallel straight waveguide (15), a first output straight waveguide (17), a second output straight waveguide (18) and a third output straight waveguide (19) having the same structure and size and being parallel to each other; the first input tapered waveguide (7), the second input tapered waveguide (8) and the third input tapered waveguide (9) respectively serve as three input ends of the multimode interference waveguide (10); the first output straight waveguide (17), the second output straight waveguide (18) and the third output straight waveguide (19) respectively serve as three output ends of the multimode interference waveguide (10); the first input straight waveguide (1), the first S-bend waveguide (4) and the first output straight waveguide (19) are connected to the first S-bend waveguide (4) and the first output straight waveguide (19); The first input tapered waveguide (7) is connected in sequence, the second input straight waveguide (2), the first parallel straight waveguide (5) and the second input tapered waveguide (8) are connected in sequence, the third input straight waveguide (3), the second S-bend waveguide (6) and the third input tapered waveguide (9) are connected in sequence; the first output tapered waveguide (11), the third S-bend waveguide (14) and the first output straight waveguide (17) are connected in sequence, the second output tapered waveguide (12), the second parallel straight waveguide (15) and the second output straight waveguide (18) are connected in sequence, and the third output tapered waveguide (13), the fourth S-bend waveguide (16) and the third output straight waveguide (19) are connected in sequence.

2. A polymer waveguide optical power divider based on MMI structure with multi-port input and multi-port output as claimed in claim 1, characterized in that: The widths of the first input straight waveguide (1), the second input straight waveguide (2), the third input straight waveguide (3), the first S-bend waveguide (4), the first parallel straight waveguide (5), the second S-bend waveguide (6), the third S-bend waveguide (14), the second parallel straight waveguide (15), the fourth S-bend waveguide (16), the first output straight waveguide (17), the second output straight waveguide (18) and the third output straight waveguide (19) are equal, that is, W1=4-6 μm; the widths of the input ends of the first output tapered waveguide (11), the second output tapered waveguide (12) and the third output tapered waveguide (13) are equal, that is, W1=4-6 μm; the widths of the first output tapered waveguide (11), the second output tapered waveguide (12) and the third output tapered waveguide (13) are equal, that is, W1=4-6 μm; the widths of the first output tapered waveguide (11), the second output tapered waveguide (12) and the third output tapered waveguide (13) are equal, that is, W1=4-6 μm; the widths of the first output tapered waveguide (11) and ... The widths of the output ends of the waveguide (11), the second output tapered waveguide (12) and the third output tapered waveguide (13) are equal, namely, W1=4-6 μm; the lengths of the first input straight waveguide (1), the second input straight waveguide (2) and the third input straight waveguide (3) are equal, namely, L1=500-3000 μm; the projected lengths of the first S-bend waveguide (4) and the second S-bend waveguide (6) along the first parallel straight waveguide (5) are equal, namely, L2=800-2500 μm, and the length of the first parallel straight waveguide (5) is L2=800-2500 μm; the first input tapered waveguide (7), the second input tapered waveguide (8) and the third input tapered .... The length of the guide (9) is equal to L3 = 50-200 μm; the width of the first input tapered waveguide (7), the second input tapered waveguide (8) and the third input tapered waveguide (9) at the connection with the multimode interference waveguide (10) is equal to W2 = 5-6 μm, and W2>W1; the width W3 of the multimode interference waveguide (10) is 20-30 μm, and the length L4 is 1500-2000 μm; the width W4 of the connection between the multimode interference waveguide (10) and the second output tapered waveguide (12) is 5-6 μm, and the width of the connection between the multimode interference waveguide (10) and the first output tapered waveguide (11) and the third output tapered waveguide (13) is equal W5=5-15 μm, and W5>W4; the lengths of the first output tapered waveguide (11), the second output tapered waveguide (12) and the third output tapered waveguide (13) are equal, namely L5=50-200 μm; the projection lengths of the third S-bend waveguide (14) and the fourth S-bend waveguide (16) along the second parallel straight waveguide (15) are equal, namely L6=800-2000 μm, and the length of the second parallel straight waveguide (15) is L6=800-2000 μm; the lengths of the first output straight waveguide (17), the second output straight waveguide (18) and the third output straight waveguide (19) are equal, namely L7=500-2000 μm.

3. The polymer waveguide optical power divider based on MMI structure with multi-port input and multi-port output as claimed in claim 1, characterized in that: The thickness of the silicon wafer substrate (20) is 0.5-1 mm, the thickness of the polymer lower cladding layer (21) is 3-15 μm, the thickness of the polymer optical waveguide core layer (22') is 2-10 μm, and the thickness of the polymer upper cladding layer (23) on the polymer optical waveguide core layer (22') is 3-15 μm.

4. The polymer waveguide optical power divider based on MMI structure with multi-port input and multi-port output as claimed in claim 1, characterized in that: The material of the polymer lower cladding layer (21) and the polymer upper cladding layer (23) is one of polycarbonate, polyimide, polymethyl methacrylate, polyethylene, polyester, polystyrene and EpoClad; the material of the polymer optical waveguide core layer (22') is EpoCore, SU-8 2002 or SU-8 2005.

5. A method for preparing a polymer waveguide optical power divider based on an MMI structure with multi-port input and multi-port output as claimed in claim 1, 2, 3 or 4, the steps of which are as follows: A: Cleaning of silicon wafer substrate Wipe the silicon wafer substrate (20) vigorously with a cotton ball soaked in acetone, and wipe it repeatedly 2 to 3 times; then wipe the silicon wafer substrate (20) vigorously with a cotton ball soaked in ethanol, and wipe it repeatedly 2 to 3 times; after wiping it clean, rinse it repeatedly with deionized water, and finally blow dry the silicon wafer with nitrogen, and then put it in a clean culture dish and seal it for storage; B: Preparation of the lower cladding of polymer optical waveguide The polymer lower cladding material is spin-coated on a cleaned silicon wafer substrate (20) by a spin coating process, the spin coating speed is 1000-5000 rpm, and after the spin coating is completed, it is baked at 100° C.-150° C. for 3-60 minutes; after the EpoClad material is baked, it needs to be baked at 110-130° C. for 1-10 minutes, the whole is exposed for 5-30 seconds, and then baked at 130-150° C. for 2-50 minutes; C: Preparation of polymer optical waveguide core layer The polymer optical waveguide core layer material is spin-coated on the polymer lower cladding layer (21) by a spin coating process, and the spin coating speed is 1000-5000 rpm; the obtained polymer optical waveguide core layer film (22) is pre-baked, that is, baked at 50°C-180°C for 3-30 minutes, and naturally cooled to room temperature after baking; the polymer optical waveguide core layer film (22) is subjected to plate-to-plate photolithography, the ultraviolet light wavelength emitted by the photolithography machine is 350-400nm, the waveguide mask is complementary to the structure of the polymer optical waveguide core layer (22') to be prepared, and exposure is performed when the photolithography plate is in close contact with the silicon wafer substrate, and the exposure time is 4-40 seconds, so that the polymer optical waveguide core layer film (22) within the structure of the polymer optical waveguide core layer (22') to be prepared is exposed to ultraviolet light; The silicon wafer substrate after photolithography is removed from the photolithography machine for intermediate baking, i.e., baking at 50°C to 180°C for 5 to 30 minutes, and cooling naturally to room temperature after baking; developing the polymer optical waveguide core layer (22') structure, i.e., firstly wet etching in a developer corresponding to the polymer optical waveguide core layer material for 10 to 60 seconds to remove the unexposed polymer optical waveguide core layer film (22), leaving only the polymer optical waveguide core layer (22') structure corresponding to the mask, and then washing away the developer and the polymer optical waveguide core layer material remaining on the surface of the silicon wafer with an isopropanol solution, then rinsing the isopropanol remaining on the surface with deionized water and drying with nitrogen; finally, baking at a temperature of 120°C to 150°C for 30 to 60 minutes to perform post-baking to harden the film, thereby completing the preparation of the polymer optical waveguide core layer (22') with a strip structure; D: Preparation of the upper cladding layer of polymer optical waveguide The polymer upper cladding material is spin-coated on the waveguide core layer (22') and the polymer lower cladding (21) by a spin coating process, the spin coating speed is 1000-5000 rpm, and after the spin coating is completed, it is baked at 120°C-150°C for 3-60 minutes to obtain the polymer upper cladding (23), thereby completing the preparation of the multi-port input and multi-port output polymer waveguide optical power distributor based on the MMI structure.

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