A multi-channel optical power divider based on MMI structure and a preparation method thereof

Abstract

A multi-channel optical power divider based on an MMI structure and its fabrication method are disclosed, belonging to the field of planar optical waveguide devices and their fabrication technology. From bottom to top, it consists of a silicon substrate, a polymer lower cladding, a strip-shaped polymer waveguide core layer, and a polymer upper cladding. The strip-shaped polymer waveguide core layer is based on an MMI structure and is encased within the polymer upper cladding. This waveguide-type power divider combines the advantages of large process tolerance and small size of MMI optical waveguide structures with the advantage of a wide variety of organic polymer materials, achieving the goal of equal power distribution across multiple different input ports. Furthermore, the fabrication process using polymer materials is relatively simple, requiring only conventional processes such as spin coating and photolithography, without the need for more complex processes. Moreover, it boasts low production costs, high efficiency, and the ability to be mass-produced, making it a practically applicable power divider.

Description

Technical Field

[0001] This invention belongs to the field of planar optical waveguide devices and their fabrication technology, specifically relating to a multi-channel optical power divider based on an MMI structure with Si as the substrate and organic polymer materials as the waveguide core and cladding, and its fabrication method. Background Technology

[0002] Optical power dividers, as core components of optical communication systems and on-chip optical interconnects, function to evenly distribute the power of input optical signals to several output ports, thereby achieving optical signal distribution and combining. They are fundamental components for optical switches, optical modulators, and multiplexers / demultiplexers. Optical power dividers based on planar waveguide structures can split a single input signal into multiple output signals to meet specific application requirements. They are not only highly compatible with optical fibers but also offer advantages such as compact structure, tunability, low insertion loss, and flexible design. Most current optical power dividers have a single-ended input, multi-ended output structure, such as the common 1×3, 1×6, and 1×N structures. These structures have played a crucial role in the development of optical communication, fulfilling the distribution requirements of optical signals to a certain extent, enabling the transmission of optical signals from one input port to multiple output ports, achieving simple optical signal splitting, and supporting the basic functions of optical communication systems.

[0003] However, this traditional optical power divider has significant limitations. From an input port design perspective, this single-ended input design restricts its functional expansion. It can only handle optical signal input from a single channel and cannot simultaneously meet the power distribution requirements of multiple input signals. In optical communication networks, this limitation means that when facing complex environments with multiple optical signal sources, the optical power divider cannot efficiently allocate multiple input optical signals, thus severely limiting the flexibility of the optical communication network and the entire system. This makes the optical communication system inadequate for handling complex service scenarios and multiple signal source access, affecting its adaptability and scalability.

[0004] To meet the urgent need for flexibility in modern communication networks, it is imperative to break through the limitations of traditional optical power dividers in the design of input and output ports and design an optical power divider that can achieve multi-segment input and multi-segment output. This would overcome the limitations of traditional structures, adapt to the complex and diverse usage environments of modern communication networks, and provide strong support for the further development of optical communication systems. Summary of the Invention

[0005] To overcome the shortcomings of traditional optical power dividers, the present invention aims to provide a multi-channel optical power divider based on an MMI structure with multiple port inputs and multiple port outputs, and a method for its fabrication.

[0006] This invention uses silicon as the waveguide substrate, organic polymer materials as the upper and lower cladding layers of the optical waveguide, and organic polymer materials with different refractive indices for the polymer waveguide core layer. This design fully utilizes the diversity, excellent processing performance, and low cost of existing polymer materials. The fabrication process is simple and easy to implement, compatible with semiconductor processes, easy to integrate, and suitable for large-scale production. Therefore, this invention has significant application value in the fields of optical communication and planar optical waveguide power dividers.

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

[0008] A multi-channel optical power divider based on an MMI structure comprises, from bottom to top, a silicon substrate 51, a polymer lower cladding layer 52, a strip-shaped polymer waveguide core layer 53, and a polymer upper cladding layer 54, wherein the strip-shaped polymer waveguide core layer 53 is encased within the polymer upper cladding layer 54; wherein the strip-shaped polymer waveguide core layer 53 is based on an MMI structure, as shown in the attached figure. Figure 1As shown, from left to right along the direction of light propagation, the waveguides are arranged in the following order: first input straight waveguide 1, second input straight waveguide 2, third input straight waveguide 3 (all with identical structure and size); first S-bend waveguide 4 and second S-bend waveguide 6 (all with identical structure and size); first straight waveguide 5; first input tapered waveguide 7, second input tapered waveguide 8, and third input tapered waveguide 9 (all with identical structure and size); first multimode interference waveguide 10; first output tapered waveguide 11, second output tapered waveguide 12, and third output tapered waveguide 13 (all with identical structure and size); third S-bend waveguide 14 and fourth S-bend waveguide 16 (all with identical size and size); second straight waveguide 15; third straight waveguide 17 and fourth straight waveguide 18 (all with identical structure and size); fourth input tapered waveguide 19; second multimode interference waveguide 20; fourth output tapered waveguide 21 and fifth output tapered waveguide 22 (all with identical structure and size); fifth S-bend waveguide 23 and eighth S-bend waveguide 26 (all with identical structure and size); and sixth S-bend waveguide 26 (all with identical structure and size). The waveguides 24 and 25 are curved, and the fifth, sixth, seventh, and eighth input tapered waveguides 27, 28, 29, and 30 are identical in structure and size. The third and fourth multimode interference waveguides 31 and 32 are identical in structure and size. The sixth, eighth, ninth, and eleventh output tapered waveguides 33, 35, 36, and 38 are identical in structure and size. The seventh output tapered waveguide 38 is identical in structure and size. The system comprises a tenth output tapered waveguide 34 and a tenth output tapered waveguide 37, a ninth S-bend waveguide 39, a tenth S-bend waveguide 41, an eleventh S-bend waveguide 42 and a twelfth S-bend waveguide 44 with the same structure and size, a fifth straight waveguide 40 and a sixth straight waveguide 43 with the same structure and size, and a first output straight waveguide 45, a second output straight waveguide 46, a third output straight waveguide 47, a fourth output straight waveguide 48, a fifth output straight waveguide 49 and a sixth output straight waveguide 50 with the same structure and size.

[0009] The first multimode interferometric waveguide 10 has three input terminals and three output terminals. The first input tapered waveguide 7, the second input tapered waveguide 8, and the third input tapered waveguide 9 serve as the three input terminals of the first multimode interferometric waveguide 10, and the first output tapered waveguide 11, the second output tapered waveguide 12, and the third output tapered waveguide 13 serve as the three output terminals of the first multimode interferometric waveguide 10. The second multimode interferometric waveguide 20 has one input terminal and two output terminals. The fourth input tapered waveguide 19 serves as the one input terminal of the second multimode interferometric waveguide 20, and the fourth output tapered waveguide 21 and the fifth output tapered waveguide 22 serve as the two output terminals of the second multimode interferometric waveguide 20. The third multimode interferometric waveguide 31 and the fourth multimode interferometric waveguide... Waveguide 32 has 2 input terminals and 3 output terminals respectively; the fifth input tapered waveguide 27 and the sixth input tapered waveguide 28 serve as 2 input terminals of the third multimode interference waveguide 31, the seventh input tapered waveguide 29 and the eighth input tapered waveguide 30 serve as 2 input terminals of the fourth multimode interference waveguide 32, the sixth output tapered waveguide 33, the seventh output tapered waveguide 34 and the eighth output tapered waveguide 35 serve as 3 output terminals of the third multimode interference waveguide 31, and the ninth output tapered waveguide 36, the tenth output tapered waveguide 37 and the eleventh output tapered waveguide 38 serve as 3 output terminals of the fourth multimode interference waveguide 32; the first input straight waveguide 1, the first S-bend waveguide 4 and the first input tapered waveguide 7 are connected sequentially, the... Two input straight waveguides 2, 5, and 8 are connected sequentially; third input straight waveguide 3, 6, and 9 are connected sequentially. First output tapered waveguide 11, 14, 17, 23, and 27 are connected sequentially; second output tapered waveguide 12, 15, and 19 are connected sequentially; fourth output tapered waveguide 21, 24, and 28 are connected sequentially; fifth output tapered waveguide 22, 25, and 29 are connected sequentially; third output tapered waveguide 13 and 16 are connected sequentially. The fourth straight waveguide 18, the eighth S-bend waveguide 26, and the eighth input tapered waveguide 30 are connected in sequence; the sixth output tapered waveguide 33, the ninth S-bend waveguide 39, and the first output straight waveguide 45 are connected in sequence; the seventh output tapered waveguide 34, the fifth straight waveguide 40, and the second output straight waveguide 46 are connected in sequence; the eighth output tapered waveguide 35, the tenth S-bend waveguide 41, and the third output straight waveguide 47 are connected in sequence; the ninth output tapered waveguide 36, the eleventh S-bend waveguide 42, and the fourth output straight waveguide 48 are connected in sequence; the tenth output tapered waveguide 37, the sixth straight waveguide 43, and the fifth output straight waveguide 49 are connected in sequence; and the eleventh output tapered waveguide 38, the twelfth S-bend waveguide 44, and the sixth output straight waveguide 50 are connected in sequence.

[0010] The widths of the following waveguides are the same: first input straight waveguide 1, second input straight waveguide 2, third input straight waveguide 3, first S-bend waveguide 4, first straight waveguide 5, second S-bend waveguide 6, third S-bend waveguide 14, second straight waveguide 15, fourth S-bend waveguide 16, third straight waveguide 17, fourth straight waveguide 18, fifth S-bend waveguide 23, eighth S-bend waveguide 26, sixth S-bend waveguide 24, seventh S-bend waveguide 25, ninth S-bend waveguide 39, tenth S-bend waveguide 41, eleventh S-bend waveguide 42, twelfth S-bend waveguide 44, fifth straight waveguide 40, sixth straight waveguide 43, first output straight waveguide 45, second output straight waveguide 46, third output straight waveguide 47, fourth output straight waveguide 48, fifth output straight waveguide 49, and sixth output straight waveguide 50, all of which have a width of W1 = 4~6μm; first input tapered waveguide 7, second input tapered waveguide 8. The width of the input end of the third input tapered waveguide 9 is the same as that of the first output tapered waveguide 11, the second output tapered waveguide 12 and the third output tapered waveguide 13, which are all W1 = 4 ~ 6 μm. The width of the input end of the fourth input tapered waveguide 19 is W1 = 4 ~ 6 μm. The width of the output ends of the fourth output tapered waveguide 21 and the fifth output tapered waveguide 22 is the same as that of the fifth input tapered waveguide 27, the sixth input tapered waveguide 28, the seventh input tapered waveguide 29 and the eighth input tapered waveguide 30, which are all W1 = 4 ~ 6 μm. The width of the output ends of the sixth output tapered waveguide 33, the seventh output tapered waveguide 34, the eighth output tapered waveguide 35, the ninth output tapered waveguide 36, the tenth output tapered waveguide 37 and the eleventh output tapered waveguide 38 is the same as that of the third input tapered waveguide 9, which are all W1 = 4 ~ 6 μm.

[0011] The first input straight waveguide 1, the second input straight waveguide 2, and the third input straight waveguide 3 have the same length, L1 = 500–3000 μm; the first S-bend waveguide 4 and the second S-bend waveguide 6 have the same projection length along the first straight waveguide 5, L2 = 800–2500 μm; the first input tapered waveguide 7, the second input tapered waveguide 8, and the third input tapered waveguide 9 have the same length, L3 = 50–200 μm; the width at the connection between the first input tapered waveguide 7, the second input tapered waveguide 8, and the third input tapered waveguide 9 and the first multimode interference waveguide 10 is the same, W2 = 5–7 μm, and W2 > W1; the first multimode... The width W3 of the interference waveguide 10 is 20–30 μm, and the length L4 is 2500–3000 μm. The width at the connection between the first multimode interference waveguide 10 and the first output tapered waveguide 11, the second output tapered waveguide 12, and the third output tapered waveguide 13 is the same, W4 = 5–7 μm, and W4 = W2 > W1. The lengths of the first output tapered waveguide 11, the second output tapered waveguide 12, and the third output tapered waveguide 13 are the same, L5 = 50–200 μm. The length L6 of the second straight waveguide 15 is 800–2000 μm. The projection lengths of the third S-bend waveguide 14 and the fourth S-bend waveguide 16 along the second straight waveguide 15 are the same, L. 10 =2000~3000μm; the third straight waveguide 17 and the fourth straight waveguide 18 have the same length L. 11 =50~200μm; the length L7 of the fourth input tapered waveguide 19 is 200~500μm; the width W5 at the connection between the input tapered waveguide 19 and the second multimode interference waveguide 20 is 8~10μm; the length L8 of the second multimode interference waveguide 20 is 400~500μm, and the width W6 is 20~30μm; the lengths of the fourth output tapered waveguide 21 and the fifth output tapered waveguide 22 are the same, L9 = 60~200μm; the width at the connection between the second multimode interference waveguide 20 and the fourth output tapered waveguide 21 and the fifth output tapered waveguide 22 is the same, W7 = 6~15μm; the projection lengths of the sixth S-bend waveguide 24 and the seventh S-bend waveguide 25 along the extension line of the second direct waveguide 15 are the same, L 14 =2000~2500μm; the projection lengths of the fifth S-bend waveguide 23 and the ninth S-bend waveguide 26 along the extension line of the second direct waveguide 15 are the same, L. 12 =1500~2000μm; the fifth input tapered waveguide 27, the sixth input tapered waveguide 28, the seventh input tapered waveguide 29, and the eighth input tapered waveguide 30 have the same length L. 13=50~100μm, the width at the connection of the fifth input tapered waveguide 27, the sixth input tapered waveguide 28 and the third multimode interference waveguide 31 and the width at the connection of the seventh input tapered waveguide 29, the eighth input tapered waveguide 30 and the fourth multimode interference waveguide 32 are the same, W8 = 5~10μm; the length of the third multimode interference waveguide 31 and the fourth multimode interference waveguide 32 is the same, L. 15 =1500~2000μm, with the same width W9 =25~30μm; the width at the connection between the third multimode interference waveguide 31 and the sixth output tapered waveguide 33 and the eighth output tapered waveguide 35, as well as the width at the connection between the fourth multimode interference waveguide 32 and the ninth output tapered waveguide 36 and the eleventh output tapered waveguide 38, is the same as W 10 =5~15μm; the width W at the connection between the third multimode interference waveguide 31 and the seventh output tapered waveguide 34 11 =5~15μm; the width W at the connection between the fourth multimode interference waveguide 32 and the tenth output tapered waveguide 37 11 =5~15μm; W 11 <W 10 The sixth output tapered waveguide 33, the seventh output tapered waveguide 34, the eighth output tapered waveguide 35, the ninth output tapered waveguide 36, the tenth output tapered waveguide 37, and the eleventh output tapered waveguide 38 have the same length L. 16 =50~100μm; The projected lengths of the ninth S-bend waveguide 39, the tenth S-bend waveguide 41, the eleventh S-bend waveguide 42, and the twelfth S-bend waveguide 44 along the fifth straight waveguide 40 and the sixth straight waveguide 43 are the same as the lengths of the fifth straight waveguide 40 and the sixth straight waveguide 43, which is L. 17 =1500~2000μm; the first output straight waveguide 45, the second output straight waveguide 46, the third output straight waveguide 47, the fourth output straight waveguide 48, the fifth output straight waveguide 49, and the sixth output straight waveguide 50 have the same length L. 18 =500~2000μm.

[0012] As attached Figure 2 As shown, the multi-port input optical power divider consists of, from bottom to top, a silicon substrate 51, a polymer lower cladding 52 fabricated on the silicon substrate 51, a strip-shaped polymer waveguide core layer 53 fabricated on the polymer lower cladding 52, and a polymer upper cladding 54 fabricated on the polymer waveguide core layer 53 and the polymer lower cladding 52; the polymer waveguide core layer 53 is embedded in the polymer upper cladding 54. The polymer waveguide core layer 53 at this point comprises a third S-bend waveguide 14, a second straight waveguide 15, and a fourth S-bend waveguide 16.

[0013] When the signal light is input from the first input straight waveguide 1 or the third input straight waveguide 3, it passes through the first S-bend waveguide 4 or the second S-bend waveguide 6 and then enters the first input tapered waveguide 7 or the third input tapered waveguide 9, respectively. It then enters the first multimode interference waveguide 10, exciting multiple modes with the same frequency. Coupling and superposition between these modes cause changes in the phase of the optical field, resulting in mutual interference. According to the self-imaging principle of MMI, the interfering light is evenly split into two parts and enters the first output tapered waveguide 11 and the third output tapered waveguide 13, respectively. Subsequently, it passes through the third S-bend waveguide 14 and the fourth S-bend waveguide 16, respectively, and then enters the third straight waveguide 17 and the fourth straight waveguide 18 for output. Finally, it passes through the fifth S-bend waveguide 23 and the eighth S-bend waveguide 26, respectively, and enters the fifth input tapered waveguide 27 and... The eighth input conical waveguide 30 enters the third multimode interference waveguide 31 and the fourth multimode interference waveguide 32 respectively. After mutual interference, the two beams (with the same phase difference) are divided into three equal parts and enter the sixth output conical waveguide 33, the seventh output conical waveguide 34, the eighth output conical waveguide 35, the ninth output conical waveguide 36, the tenth output conical waveguide 37 and the eleventh output conical waveguide 38 respectively. Then, they pass through the ninth S-bend waveguide 39, the fifth straight waveguide 40, the tenth S-bend waveguide 41, the eleventh S-bend waveguide 42, the sixth straight waveguide 43 and the twelfth S-bend waveguide 44 respectively and enter the first output straight waveguide 45, the second output straight waveguide 46, the third output straight waveguide 47, the fourth output straight waveguide 48, the fifth output straight waveguide 49 and the sixth output straight waveguide 50 for output.

[0014] When light enters from the second input straight waveguide 2, it passes through the first straight waveguide 5 into the second tapered waveguide 8, then through the first multimode interference waveguide 10 into the second output tapered waveguide 12. After passing through the second straight waveguide 15 and the fourth input tapered waveguide 19, it enters the second multimode interference waveguide 20, exciting multiple modes with the same frequency. Coupling and superposition between these modes cause changes in the phase of the optical field, resulting in mutual interference. According to the self-imaging principle of MMI, the interfering light splits into two parts, entering the fourth output tapered waveguide 21 and the fifth output tapered waveguide 22. The light then passes through the sixth S-bend waveguide 24 and the seventh S-bend waveguide 25, respectively, into the sixth input tapered waveguide 28 and the seventh input tapered waveguide 29, and then through the third multimode interference waveguide 20. After waveguide 31 and the fourth multimode interferometer waveguide 32 interfere with each other, the two beams (with the same phase difference) are then divided into three beams, which enter the sixth output tapered waveguide 33, the seventh output tapered waveguide 34, the eighth output tapered waveguide 35, the ninth output tapered waveguide 36, the tenth output tapered waveguide 37, and the eleventh output tapered waveguide 38, respectively. Then, they pass through the ninth S-bend waveguide 39, the fifth straight waveguide 40, the tenth S-bend waveguide 41, the eleventh S-bend waveguide 42, the sixth straight waveguide 43, and the twelfth S-bend waveguide 44, respectively, and enter the first output straight waveguide 45, the second output straight waveguide 46, the third output straight waveguide 47, the fourth output straight waveguide 48, the fifth output straight waveguide 49, and the sixth output straight waveguide 50 for output.

[0015] The silicon substrate 51 has a thickness of 0.5–1 mm, the polymer lower cladding layer 52 has a thickness of 1–8 μm, the polymer waveguide core layer 53 has a thickness of 1–10 μm, and the polymer upper cladding layer 54 above the polymer waveguide core layer has a thickness of 1–8 μm.

[0016] The fabrication process of the MMI-based polymer power divider described in this invention is shown in the appendix. Figure 3 The specific steps are as follows:

[0017] A: Cleaning of silicon wafer substrates

[0018] First, use cotton balls soaked in acetone to repeatedly wipe the silicon substrate 51 with a thickness of 0.5-1 mm. Then, use cotton balls soaked in ethanol to vigorously and repeatedly wipe the silicon substrate. After wiping it clean, rinse it repeatedly with deionized water. Finally, blow the silicon substrate 51 dry with nitrogen gas and then put it into a clean petri dish for sealed storage.

[0019] B: Fabrication of the cladding under the polymer optical waveguide

[0020] A polymer undercoating material (which is a series of transparent organic polymer materials including polycarbonate (PC), polyimide (PI), polymethyl methacrylate (PMMA), polyethylene (PE), polyester (PET), polystyrene (PS), EpoClad, etc.) is spin-coated onto one side surface of a clean silicon wafer substrate 51 using a spin-coating process. The spin-coating speed is 1000-5000 rpm. After spin-coating, the substrate is baked at 100℃-150℃ for 3-60 minutes (for special materials such as EpoClad, after baking, the entire substrate needs to be exposed for 5-30 seconds, and then baked at 120℃-150℃ for 3-60 minutes). The thickness of the resulting polymer undercoating 52 is 1-8 μm.

[0021] C: Fabrication of the polymer optical waveguide core layer

[0022] A polymer waveguide core layer material (which is a series of wet-etchable ultraviolet negative photoresist materials including EpoCore, SU-8 2002, and SU-8 2005, with a refractive index higher than that of the polymer upper and lower cladding layers) is spin-coated onto the polymer lower cladding layer 52 to form a polymer waveguide core layer film 53'. The spin-coating speed is 1000–5000 rpm, and the thickness of the resulting polymer waveguide core layer film 53' is 1–10 μm. The resulting polymer waveguide core layer film 53' is pre-baked at 50°C–180°C for 3–30 minutes, and then allowed to cool naturally to room temperature. The polymer waveguide core layer film 53' is then subjected to photolithography. The ultraviolet light emitted by the photolithography machine has a wavelength of 350–400 nm. The waveguide mask and the polymer waveguide core layer 53 of the power divider to be fabricated have complementary structures (e.g., ...). Figure 1 As shown, when the photomask is firmly attached to the silicon substrate 51, exposure is performed for 4–40 seconds to expose the polymer waveguide core layer film within the desired polymer waveguide core layer 53 structure to ultraviolet light. The photolithographically lithographically formed silicon substrate 51 is then removed from the photolithography machine and subjected to intermediate baking at 50°C–180°C for 5–30 minutes, followed by natural cooling to room temperature. The polymer waveguide core layer film 53' is then developed, i.e., wet etching is performed in the developer corresponding to the polymer waveguide core layer material. Etching for 10–60 seconds removes the unexposed non-polymer waveguide core layer structure, leaving only the polymer waveguide core layer structure corresponding to the mask. Then, isopropanol solution is used to wash away the developer and residual polymer waveguide core layer material on the surface of silicon substrate 51. The surface is then rinsed with deionized water to remove residual isopropanol and dried with nitrogen. Finally, it is baked at 120°C–150°C for 30–60 minutes for post-baking hardening, thus completing the fabrication of the strip-shaped polymer waveguide core layer 53.

[0023] D: Fabrication of the cladding on the polymer optical waveguide

[0024] The polymer upper cladding material is spin-coated onto the polymer waveguide core layer 53 and the polymer lower cladding layer 52 using a spin-coating process. The spin-coating speed is 1000-5000 rpm. After spin-coating, the material is baked at 120℃-150℃ for 3-60 minutes. The thickness of the polymer upper cladding layer 54 on the polymer waveguide core layer is 1-8 μm. This completes the fabrication of the multi-port input power divider described in this invention.

[0025] Compared with existing device structures and fabrication techniques, the advantages of this invention are:

[0026] The waveguide-type power divider of this invention combines the advantages of large tolerance and small size of MMI optical waveguide structure technology, and also utilizes the 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 fabricating devices using polymer materials is relatively simple, requiring only conventional processes such as spin coating and photolithography, without the need for more difficult processes. Moreover, it has low production cost, high efficiency, and can be mass-produced, making it a power divider that can be applied in practice. Attached Figure Description

[0027] Figure 1 : A schematic diagram of the structure of the multi-channel optical power divider based on the MMI structure described in this invention;

[0028] Figure 2 : Figure 1 Schematic diagram of the cross-section at point AA';

[0029] Figure 3 : Flowchart of the fabrication process of the multi-port input optical power divider of the present invention;

[0030] Figure 4 (a): The left figure is a simulation diagram of the optical field transmission of the multi-port input optical power divider from the first input straight waveguide 1, and the right figure is a diagram of the transmission efficiency of the device for different lengths;

[0031] Figure 4 (b) The left figure shows the optical field transmission simulation diagram of the multi-port input optical power divider from the second input straight waveguide 2, and the right figure shows the transmission efficiency diagram of the device for different lengths.

[0032] Figure 4 (c): The left figure is a simulation diagram of the optical field transmission of the multi-port input optical power divider from the third input straight waveguide 3, and the right figure is a diagram of the transmission efficiency of the device for different lengths;

[0033] Figure 5(a): Curve showing the relationship between normalized output power and wavelength when the multi-port input optical power divider is input from the first input straight waveguide 1;

[0034] Figure 5 (b): Curve showing the relationship between normalized output power and wavelength when the multi-port input optical power divider is input from the second input straight waveguide 2;

[0035] Figure 5 (c): Curve showing the relationship between normalized output power and wavelength when the multi-port input optical power divider is input from the third input straight waveguide 3. Detailed Implementation

[0036] Example 1

[0037] like Figure 1 As shown, the multi-port input optical power divider consists of a first input straight waveguide 1, a second input straight waveguide 2, a third input straight waveguide 3, a first S-bend waveguide 4 and a second S-bend waveguide 6, a first straight waveguide 5, a first input tapered waveguide 7, a second input tapered waveguide 8, a third input tapered waveguide 9, a first 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-bend waveguide 14, a fourth S-bend waveguide 16, a second straight waveguide 15, a third straight waveguide 17, a fourth straight waveguide 18, a fourth input tapered waveguide 19, a second multimode interference waveguide 20, a fourth output tapered waveguide 21, a fifth output tapered waveguide 22, a fifth S-bend waveguide 23, an eighth S-bend waveguide 26, a sixth S-bend waveguide 24, and a seventh S-bend waveguide 25. The waveguide consists of S-bend waveguide 25, fifth input tapered waveguide 27, sixth input tapered waveguide 28, seventh input tapered waveguide 29, eighth input tapered waveguide 30, third multimode interference waveguide 31, fourth multimode interference waveguide 32, sixth output tapered waveguide 33, eighth output tapered waveguide 35, ninth output tapered waveguide 36, eleventh output tapered waveguide 38, seventh output tapered waveguide 34, tenth output tapered waveguide 37, ninth S-bend waveguide 39, tenth S-bend waveguide 41, eleventh S-bend waveguide 42, twelfth S-bend waveguide 44, fifth straight waveguide 40, sixth straight waveguide 43, first output straight waveguide 45, second output straight waveguide 46, third output straight waveguide 47, fourth output straight waveguide 48, fifth output straight waveguide 49, and sixth output straight waveguide 50.

[0038] The first multimode interferometric waveguide 10 has three input terminals and three output terminals. The first input tapered waveguide 7, the second input tapered waveguide 8, and the third input tapered waveguide 9 serve as the three input terminals of the first multimode interferometric waveguide 10, and the first output tapered waveguide 11, the second output tapered waveguide 12, and the third output tapered waveguide 13 serve as the three output terminals of the first multimode interferometric waveguide 10. The second multimode interferometric waveguide 20 has one input terminal and two output terminals. The fourth input tapered waveguide 19 serves as the input terminal of the second multimode interferometric waveguide 20, and the fourth output tapered waveguide 21 and the fifth output tapered waveguide 22 serve as the two output terminals of the second multimode interferometric waveguide 20. The third multimode interferometric waveguide 31 and the fourth multimode interferometric waveguide 32... Each has 2 input terminals and 3 output terminals; the fifth input tapered waveguide 27 and the sixth input tapered waveguide 28 serve as the 2 input terminals of the third multimode interference waveguide 31, the seventh input tapered waveguide 29 and the eighth input tapered waveguide 30 serve as the 2 input terminals of the fourth multimode interference waveguide 32, the sixth output tapered waveguide 33, the seventh output tapered waveguide 34 and the eighth output tapered waveguide 35 serve as the 3 output terminals of the third multimode interference waveguide 31, and the ninth output tapered waveguide 36, the tenth output tapered waveguide 37 and the eleventh output tapered waveguide 38 serve as the 3 output terminals of the fourth multimode interference waveguide 32; the first input straight waveguide 1, the first S-bend waveguide 4 and the first input tapered waveguide 7 are connected sequentially, the second... Input straight waveguide 2, first straight waveguide 5, and second input tapered waveguide 8 are connected sequentially; third input straight waveguide 3, second S-bend waveguide 6, and third input tapered waveguide 9 are connected sequentially; first output tapered waveguide 11, third S-bend waveguide 14, third straight waveguide 17, fifth S-bend waveguide 23, and fifth input tapered waveguide 27 are connected sequentially; second output tapered waveguide 12, second straight waveguide 15, and fourth input tapered waveguide 19 are connected sequentially; fourth output tapered waveguide 21, sixth S-bend waveguide 24, and sixth input tapered waveguide 28 are connected sequentially; fifth output tapered waveguide 22, seventh S-bend waveguide 25, and seventh input tapered waveguide 29 are connected sequentially; third output tapered waveguide 13 and fourth S-bend waveguide 16 are connected sequentially. The fourth straight waveguide 18, the eighth S-bend waveguide 26, and the eighth input tapered waveguide 30 are connected in sequence. The sixth output tapered waveguide 33, the ninth S-bend waveguide 39, and the first output straight waveguide 45 are connected in sequence. The seventh output tapered waveguide 34, the fifth straight waveguide 40, and the second output straight waveguide 46 are connected in sequence. The eighth output tapered waveguide 35, the tenth S-bend waveguide 41, and the third output straight waveguide 47 are connected in sequence. The ninth output tapered waveguide 36, the eleventh S-bend waveguide 42, and the fourth output straight waveguide 48 are connected in sequence. The tenth output tapered waveguide 37, the sixth straight waveguide 43, and the fifth output straight waveguide 49 are connected in sequence. The eleventh output tapered waveguide 38, the twelfth S-bend waveguide 44, and the sixth output straight waveguide 50 are connected in sequence.

[0039] The first input straight waveguide 1, the second input straight waveguide 2, the third input straight waveguide 3, the first S-curved waveguide 4, the first straight waveguide 5, the second S-curved waveguide 6, the third S-curved waveguide 14, the second straight waveguide 15, the fourth S-curved waveguide 16, the third straight waveguide 17, the fourth straight waveguide 18, the fifth S-curved waveguide 23, the sixth S-curved waveguide 24, the seventh S-curved waveguide 25, the eighth S-curved waveguide 26, the ninth S-curved waveguide 39, the tenth S-curved waveguide 41, the eleventh S-curved waveguide 42, the twelfth S-curved waveguide 44, the fifth straight waveguide 40, the sixth straight waveguide 43, the first output straight waveguide 45, the second output straight waveguide 46, the third output straight waveguide 47, the fourth output straight waveguide 48, the fifth output straight waveguide 49, and the sixth output straight waveguide 50 all have the same width W1 = 4; the first input tapered waveguide 7, the second input tapered waveguide 50, and the second input tapered waveguide 6... The widths of the input ends of the first, second, and third output tapered waveguides 11, 12, and 13 are the same, W1 = 4 μm. The width of the input end of the fourth input tapered waveguide 19 is W1 = 4 μm. The widths of the output ends of the fourth, fifth, and sixth output tapered waveguides 21 and 22 are the same, W1 = 4 μm. The widths of the input ends of the fifth, sixth, seventh, and eighth input tapered waveguides 27, 28, 29, and 30 are the same, W1 = 4 μm. The widths of the output ends of the sixth, seventh, eighth, ninth, tenth, and eleventh output tapered waveguides 33, 34, 35, 36, 37, and 38 are the same, W1 = 4 μm.

[0040] The first input straight waveguide 1, the second input straight waveguide 2, and the third input straight waveguide 3 have the same length, L1 = 500 μm; the first S-bend waveguide 4 and the second S-bend waveguide 6 have the same projection length along the first straight waveguide 5, L2 = 1500 μm; the first input tapered waveguide 7, the second input tapered waveguide 8, and the third input tapered waveguide 9 have the same length, L3 = 60 μm; the width at the connection point between the first input tapered waveguide 7, the second input tapered waveguide 8, and the third input tapered waveguide 9 and the first multimode interference waveguide 10 is the same, W2. =6μm; the width W3 of the first multimode interference waveguide 10 is 25μm, and the length L4 is 2580μm; the width at the connection between the first multimode interference waveguide 10 and the first output tapered waveguide 11, the second output tapered waveguide 12, and the third output tapered waveguide 13 is the same, W4 = 6μm; the lengths of the first output tapered waveguide 11, the second output tapered waveguide 12, and the third output tapered waveguide 13 are the same, L5 = 50μm; the length L6 of the second straight waveguide 15 is 800μm; the lengths of the third S-bend waveguide 14 and the fourth S-bend waveguide 16 are the same, L 10=2000μm; the third straight waveguide 17 and the fourth straight waveguide 18 have the same length L. 11 =50μm; the length L7 of the fourth input tapered waveguide 19 is 200μm; the width W5 at the connection between the input tapered waveguide 19 and the second multimode interference waveguide 20 is 8μm; the length L8 of the second multimode interference waveguide 20 is 406.66μm, and the width W6 is 20μm; the lengths of the fourth output tapered waveguide 21 and the fifth output tapered waveguide 22 are the same, L9 = 60μm; the width at the connection between the second multimode interference waveguide 20 and the fourth output tapered waveguide 21 and the fifth output tapered waveguide 22 is the same, W7 = 6μm; the projection lengths of the sixth S-bend waveguide 24 and the seventh S-bend waveguide 25 along the extension line of the second direct waveguide 15 are the same, L 14 =2383.34μm; the projected lengths of the fifth S-bend waveguide 23 and the ninth S-bend waveguide 26 along the extension line of the second direct waveguide 15 are the same, L. 12 =1800μm; the fifth input tapered waveguide 27, the sixth input tapered waveguide 28, the seventh input tapered waveguide 29, and the eighth input tapered waveguide 30 have the same length L. 13 =60μm, the width at the connection of the fifth input tapered waveguide 27, the sixth input tapered waveguide 28 and the third multimode interference waveguide 31, and the width at the connection of the seventh input tapered waveguide 29, the eighth input tapered waveguide 30 and the fourth multimode interference waveguide 32 are the same, W8 = 6.6μm; the length of the third multimode interference waveguide 31 and the fourth multimode interference waveguide 32 is the same, L. 15 =1729μm, with the same width W9 = 25μm; the width at the connection between the third multimode interference waveguide 31 and the sixth output tapered waveguide 33 and the eighth output tapered waveguide 35, as well as the width at the connection between the fourth multimode interference waveguide 32 and the ninth output tapered waveguide 36 and the eleventh output tapered waveguide 38, is the same as W 10 =6μm; the width W at the connection between the third multimode interference waveguide 31 and the seventh output tapered waveguide 34 11 = 5.2μm; the width W at the connection between the fourth multimode interference waveguide 32 and the tenth output tapered waveguide 37 11 = 5.2μm; the sixth output tapered waveguide 33, the seventh output tapered waveguide 34, the eighth output tapered waveguide 35, the ninth output tapered waveguide 36, the tenth output tapered waveguide 37, and the eleventh output tapered waveguide 38 have the same length L. 16 =97.47μm; The projected lengths of the ninth S-bent waveguide 39, the tenth S-bent waveguide 41, the eleventh S-bent waveguide 42, and the twelfth S-bent waveguide 44 along the fifth straight waveguide 40 and the sixth straight waveguide 43 are the same as the lengths of the fifth straight waveguide 40 and the sixth straight waveguide 43, which is L. 17=2000μm; the first output straight waveguide 45, the second output straight waveguide 46, the third output straight waveguide 47, the fourth output straight waveguide 48, the fifth output straight waveguide 49, and the sixth output straight waveguide 50 have the same length L. 18 =500μm.

[0041] As attached Figure 2 As shown, from bottom to top, the structure consists of a silicon substrate 51, a polymer lower cladding layer 52 fabricated on the silicon substrate 51, a strip-shaped polymer waveguide core layer 53 fabricated on the polymer lower cladding layer 52, and a polymer upper cladding layer 54 fabricated on the polymer waveguide core layer 53. The thickness of the silicon substrate 51 is 1 mm, the thickness of the polymer lower cladding layer 52 is 5 μm, the thickness of the polymer waveguide core layer 53 is 5 μm, and the thickness of the polymer upper cladding layer 54 is 5 μm (the thickness of the polymer upper cladding layer above the polymer waveguide core layer).

[0042] Figure 4 (a): Simulation diagram of optical field transmission from the first input straight waveguide 1 to the multi-port input optical power divider. In the simulation process, we selected the materials and waveguide dimensions used in Example 1. It can be clearly seen from the simulation diagram that when the input is the fundamental mode at a wavelength of 850nm, the outputs from the first output straight waveguide 45, the second output straight waveguide 46, the third output straight waveguide 47, the fourth output straight waveguide 48, the fifth output straight waveguide 49 and the sixth output straight waveguide 50 are the fundamental modes with the same power.

[0043] Figure 4 (b): Simulation diagram of optical field transmission from the input of the multi-port input optical power divider to the first input straight waveguide 2. In the simulation process, we selected the materials and waveguide dimensions used in Example 1. It can be clearly seen from the simulation diagram that when the input is the fundamental mode at a wavelength of 850nm, the outputs from the first output straight waveguide 45, the second output straight waveguide 46, the third output straight waveguide 47, the fourth output straight waveguide 48, the fifth output straight waveguide 49 and the sixth output straight waveguide 50 are the fundamental modes with the same power.

[0044] Figure 4 (c): Simulation diagram of optical field transmission from the third input straight waveguide 3 to the multi-port input optical power divider. In the simulation, we used the materials and waveguide dimensions selected in Example 1. It can be clearly seen from the simulation diagram that when the input is the fundamental mode at a wavelength of 850nm, the outputs from the first output straight waveguide 45, the second output straight waveguide 46, the third output straight waveguide 47, the fourth output straight waveguide 48, the fifth output straight waveguide 49 and the sixth output straight waveguide 50 are the fundamental modes with the same power.

[0045] like Figure 5(a) is the curve showing the relationship between the normalized output power and wavelength when the multi-port input optical power divider is input from the input waveguide 1. We used the materials and waveguide dimensions selected in Example 1. It can be seen that in the 800-900nm band, the output power fluctuates less with wavelength. The fundamental mode with the same output power from the first output straight waveguide 45, the second output straight waveguide 46, the third output straight waveguide 47, the fourth output straight waveguide 48, the fifth output straight waveguide 49 and the sixth output straight waveguide 50 indicates that the device is not sensitive to wavelength.

[0046] like Figure 5 (b) is the curve showing the relationship between the normalized output power and wavelength when the multi-port input optical power divider is input from the second input straight waveguide 2. We used the materials and waveguide dimensions selected in Example 1. It can be seen that in the 800-900nm band, the output power fluctuates less with wavelength. The fundamental mode with the same output power from the first output straight waveguide 45, the second output straight waveguide 46, the third output straight waveguide 47, the fourth output straight waveguide 48, the fifth output straight waveguide 49 and the sixth output straight waveguide 50 indicates that the device is not sensitive to wavelength.

[0047] like Figure 5 (c) is the curve showing the relationship between the normalized output power and wavelength when the multi-port input optical power divider is input from the third input straight waveguide 3. We used the materials and waveguide dimensions selected in Example 1. It can be seen that in the 800-900nm band, the output power fluctuates less with wavelength. The fundamental mode with the same output power from the first output straight waveguide 45, the second output straight waveguide 46, the third output straight waveguide 47, the fourth output straight waveguide 48, the fifth output straight waveguide 49 and the sixth output straight waveguide 50 indicates that the device is not sensitive to wavelength.

[0048] Example 2

[0049] like Figure 3 As shown in the figure, 51 is the silicon substrate, 52 is the polymer lower cladding layer prepared by spin coating, 53 is the polymer waveguide core layer prepared by spin coating, photolithography, and wet etching, and 54 is the polymer upper cladding layer prepared by spin coating. The specific steps are as follows:

[0050] (1) Cleaning treatment of silicon wafer substrate: Wipe the silicon wafer substrate 51 vigorously with a cotton ball soaked in acetone, repeat three times, then wipe the silicon wafer substrate 51 vigorously with a cotton ball soaked in ethanol, repeat three times. After wiping it clean, rinse it repeatedly with deionized water, and finally blow the silicon wafer dry with nitrogen gas. Then put it into a clean petri dish and seal it for storage.

[0051] (2) Preparation of polymer waveguide under-cladding: The EpoClad polymer under-cladding was spin-coated onto a clean silicon wafer substrate using a spin-coating process. The spin-coating speed was 3000 rpm. After spin-coating, the substrate was baked at 120°C for 5 minutes, exposed for 12 seconds, and then baked again at 130°C for 30 minutes. The thickness of the polymer under-cladding 52 was 5 μm.

[0052] (3) The polymer waveguide core layer 53, including the input / output region and the multimode interference region, is fabricated using spin coating, photolithography, and wet etching processes: The EpoCore polymer waveguide core layer is spin-coated onto the polymer cladding layer to form a polymer waveguide core layer film 53'. The spin coating speed is 3000 rpm, and the thickness of the resulting polymer waveguide core layer film 53' is 5 μm. The resulting polymer waveguide core layer film 53' is pre-baked using a stepped heating method, first baked at 50℃ for 10 minutes, then baked at 95℃ for 15 minutes, and then cooled after baking. The fabricated polymer waveguide core layer film 53' is then subjected to photolithography. The ultraviolet light emitted by the photolithography machine has a wavelength of 365 nm, and the waveguide mask has a structure complementary to the polymer waveguide core layer 53 of the mode power divider to be fabricated (e.g., Figure 1 As shown), photolithography is performed when the photomask is firmly attached to the silicon wafer. The exposure time is 3.5 seconds, allowing the polymer waveguide core film of the device input / output region, multimode interference region, and tapered waveguide region connecting the multimode interference region and the input / output region to be exposed to ultraviolet light. After photolithography, the silicon wafer is removed from the photolithography machine and subjected to intermediate baking. It is first baked at 50°C for 10 minutes, and then at 85°C for 15 minutes. After baking, it is cooled to room temperature before proceeding to the next step. The polymer waveguide core film 5 3' Development is performed by wet etching in the developer for 60 seconds to remove the unexposed non-polymer waveguide core layer structure, leaving only the polymer waveguide core layer film corresponding to the mask. Then, the developer and the polymer waveguide core layer film remaining on the silicon wafer surface are washed away with isopropanol solution. Subsequently, the surface is rinsed with deionized water to remove the residual isopropanol and dried with nitrogen. Finally, post-baking is performed by baking at 130°C for 40 minutes, thus completing the fabrication of the strip-shaped polymer waveguide core layer 53.

[0053] (4) Fabrication of the polymer waveguide cladding: The EpoClad polymer cladding was spin-coated onto the silicon wafer with the polymer waveguide core layer 53 fabricated using a spin-coating process at a speed of 3000 rpm. After spin-coating, the wafer was baked at 120°C for 5 minutes, exposed for 12 seconds, and baked again for 3 minutes. The resulting polymer cladding on the polymer waveguide core layer had a thickness of 5 μm. This completed the fabrication of the 850nm MMI structure polymer multiport input optical power divider.

[0054] It should be noted that the specific embodiments are merely representative examples of the present invention. Obviously, the technical solutions of the present invention include, but are not limited to, the above embodiments, and can take many other forms. For example, each power divider can be cascaded as a unit structure to achieve further expansion and application. Furthermore, the materials used in this design are not limited to these; silicon, silicon nitride, lithium niobate, and other optical waveguide materials can also be used. All information explicitly disclosed in this invention or obtained without objection from the written description herein falls within the scope of protection of this invention.

Claims

1. A multi-channel optical power divider based on an MMI structure, characterized in that: From bottom to top, the structure consists of a silicon substrate (51), a polymer lower cladding (52), a strip-shaped polymer waveguide core layer (53), and a polymer upper cladding (54). The refractive index of the polymer waveguide core layer (53) is higher than that of the polymer lower cladding (52) and the polymer upper cladding (54). The strip-shaped polymer waveguide core layer (53) is encased within the polymer upper cladding (54). The strip-shaped polymer waveguide core layer (53) is based on an MMI structure and consists of a first input straight waveguide (1), a second input straight waveguide (2), and a third input straight waveguide (3) with the same structure and size, arranged sequentially from left to right along the light propagation direction. The same first S-bend waveguide (4) and second S-bend waveguide (6), first straight waveguide (5), first input tapered waveguide (7), second input tapered waveguide (8) and third input tapered waveguide (9) with the same structure and size, first multimode interference waveguide (10), first output tapered waveguide (11), second output tapered waveguide (12) and third output tapered waveguide (13) with the same structure and size, third S-bend waveguide (14) and fourth S-bend waveguide (16) with the same size, second straight waveguide (15), third straight waveguide (17) and fourth straight waveguide (18) with the same structure and size, fourth input tapered waveguide (19), second multimode interference waveguide ( 20), the fourth output tapered waveguide (21) and the fifth output tapered waveguide (22) with the same structure and size, the fifth S-bend waveguide (23) and the eighth S-bend waveguide (26) with the same structure and size, the sixth S-bend waveguide (24) and the seventh S-bend waveguide (25) with the same structure and size, the fifth input tapered waveguide (27), the sixth input tapered waveguide (28), the seventh input tapered waveguide (29) and the eighth input tapered waveguide (30) with the same structure and size, the third multimode interference waveguide (31) and the fourth multimode interference waveguide (32) with the same structure and size, and the sixth output tapered waveguide (33) and the eighth output tapered waveguide (35) with the same structure and size. The system consists of the ninth output tapered waveguide (36) and the eleventh output tapered waveguide (38), the seventh output tapered waveguide (34) and the tenth output tapered waveguide (37) with the same structure and size, the ninth S-bend waveguide (39), the tenth S-bend waveguide (41), the eleventh S-bend waveguide (42) and the twelfth S-bend waveguide (44) with the same structure and size, the fifth straight waveguide (40) and the sixth straight waveguide (43) with the same structure and size, and the first output straight waveguide (45), the second output straight waveguide (46), the third output straight waveguide (47), the fourth output straight waveguide (48), the fifth output straight waveguide (49) and the sixth output straight waveguide (50) with the same structure and size. The first multimode interferometric waveguide (10) has three input terminals and three output terminals. The first input tapered waveguide (7), the second input tapered waveguide (8), and the third input tapered waveguide (9) serve as the three input terminals of the first multimode interferometric waveguide (10), and the first output tapered waveguide (11), the second output tapered waveguide (12), and the third output tapered waveguide (13) serve as the three output terminals of the first multimode interferometric waveguide (10); the second multimode interferometric waveguide (20) The second multimode interferometric waveguide (20) has one input and two outputs. The fourth input tapered waveguide (19) serves as one input of the second multimode interferometric waveguide (20), and the fourth output tapered waveguide (21) and the fifth output tapered waveguide (22) serve as two outputs of the second multimode interferometric waveguide (20), respectively. The third multimode interferometric waveguide (31) and the fourth multimode interferometric waveguide (32) have two inputs and three outputs, respectively. The fifth input tapered waveguide (27) and the sixth input tapered waveguide (28) have one input and two outputs, respectively. Waveguide (28) serves as the two input terminals of the third multimode interferometric waveguide (31), the seventh input tapered waveguide (29) and the eighth input tapered waveguide (30) serve as the two input terminals of the fourth multimode interferometric waveguide (32), the sixth output tapered waveguide (33), the seventh output tapered waveguide (34) and the eighth output tapered waveguide (35) serve as the three output terminals of the third multimode interferometric waveguide (31), and the ninth output tapered waveguide (36) and the tenth output tapered waveguide (35) serve as the three output terminals of the third multimode interferometric waveguide (31). The eleventh output tapered waveguide (37) and the eleventh output tapered waveguide (38) serve as the three output terminals of the fourth multimode interference waveguide (32); the first input straight waveguide (1), the first S-bend waveguide (4) and the first input tapered waveguide (7) are connected in sequence; the second input straight waveguide (2), the first 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 conical waveguide (11), the third S-bend waveguide (14), the third straight waveguide (17), the fifth S-bend waveguide (23), and the fifth input conical waveguide (27) are connected in sequence. The second output conical waveguide (12), the second straight waveguide (15), and the fourth input conical waveguide (19) are connected in sequence. The fourth output conical waveguide (21), the sixth S-bend waveguide (24), and the sixth input conical waveguide (28) are connected in sequence. The fifth output conical waveguide (22), the seventh S-bend waveguide (25), and the seventh input conical waveguide (29) are connected in sequence. The third output conical waveguide (13), the fourth S-bend waveguide (16), the fourth straight waveguide (18), the eighth S-bend waveguide (26), and the eighth input conical waveguide (30) are connected in sequence. The sixth output tapered waveguide (33), the ninth S-bent waveguide (39), and the first output straight waveguide (45) are connected in sequence. The seventh output tapered waveguide (34), the fifth straight waveguide (40), and the second output straight waveguide (46) are connected in sequence. The eighth output tapered waveguide (35), the tenth S-bent waveguide (41), and the third output straight waveguide (47) are connected in sequence. The ninth output tapered waveguide (36), the eleventh S-bent waveguide (42), and the fourth output straight waveguide (48) are connected in sequence. The tenth output tapered waveguide (37), the sixth straight waveguide (43), and the fifth straight waveguide (49) are connected in sequence. The eleventh output tapered waveguide (38), the twelfth S-bent waveguide (44), and the sixth output straight waveguide (50) are connected in sequence.

2. A multi-channel optical power divider based on an MMI structure as described in claim 1, characterized in that: First input straight waveguide (1), second input straight waveguide (2), third input straight waveguide (3), first S-bend waveguide (4), first straight waveguide (5), second S-bend waveguide (6), third S-bend waveguide (14), second straight waveguide (15), fourth S-bend waveguide (16), third straight waveguide (17), fourth straight waveguide (18), fifth S-bend waveguide (23), eighth S-bend waveguide (26), sixth S-bend waveguide (24), seventh S-bend waveguide (25) The widths of the following waveguides are the same: 9S-curved waveguide (39), 10S-curved waveguide (41), 11S-curved waveguide (42), 12S-curved waveguide (44), 5th straight waveguide (40), 6th straight waveguide (43), 1st output straight waveguide (45), 2nd output straight waveguide (46), 3rd output straight waveguide (47), 4th output straight waveguide (48), 5th output straight waveguide (49), and 6th output straight waveguide (50), all with a width of W1 = 4~6μm; 1st input tapered waveguide (7). The input widths of the second input tapered waveguide (8) and the third input tapered waveguide (9) are the same, W1 = 4~6 μm. The output widths of the first output tapered waveguide (11), the second output tapered waveguide (12), and the third output tapered waveguide (13) are the same, W1 = 4~6 μm. The input width of the fourth input tapered waveguide (19) is W1 = 4~6 μm. The output widths of the fourth output tapered waveguide (21) and the fifth output tapered waveguide (22) are the same, W1 = 4~6 μm. The widths of the input ends of the fifth input tapered waveguide (27), the sixth input tapered waveguide (28), the seventh input tapered waveguide (29), and the eighth input tapered waveguide (30) are the same, W1 = 4~6μm. The widths of the output ends of the sixth output tapered waveguide (33), the seventh output tapered waveguide (34), the eighth output tapered waveguide (35), the ninth output tapered waveguide (36), the tenth output tapered waveguide (37), and the eleventh output tapered waveguide (38) are the same, W1 = 4~6μm.

3. A multi-channel optical power divider based on an MMI structure as described in claim 1, characterized in that: The lengths of the first input straight waveguide (1), the second input straight waveguide (2), and the third input straight waveguide (3) are the same, L1 = 500–3000 μm; the projection lengths of the first S-bend waveguide (4) and the second S-bend waveguide (6) along the first straight waveguide (5) are the same as the length of the first straight waveguide (5), 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 the same, L3 = 50–200 μm; the widths at the connection points between the first input tapered waveguide (7), the second input tapered waveguide (8), and the third input tapered waveguide (9) and the first multimode interference waveguide (10) are the same, W2 = 5–7 μm, and W2 > W1. The width W3 of the first multimode interference waveguide (10) is 20-30 μm, and the length L4 is 2500-3000 μm. The width of the connection between the first multimode interference waveguide (10) and the first output tapered waveguide (11), the second output tapered waveguide (12), and the third output tapered waveguide (13) is the same, W4 = 5-7 μm, and W4 = W2 > W1. The lengths of the first output tapered waveguide (11), the second output tapered waveguide (12), and the third output tapered waveguide (13) are the same, L5 = 50-200 μm. The length L6 of the second straight waveguide (15) is 800-2000 μm. The projection lengths of the third S-bend waveguide (14) and the fourth S-bend waveguide (16) along the second straight waveguide (15) are the same, L. 10 =2000~3000μm; the third straight waveguide (17) and the fourth straight waveguide (18) have the same length L 11 =50~200μm; the length L7 of the fourth input tapered waveguide (19) is 200~500μm; the width W5 at the connection between the input tapered waveguide (19) and the second multimode interference waveguide (20) is 8~10μm; the length L8 of the second multimode interference waveguide (20) is 400~500μm, and the width W6 is 20~30μm; the lengths of the fourth output tapered waveguide (21) and the fifth output tapered waveguide (22) are the same, L9 = 60~200μm; the width at the connection between the second multimode interference waveguide (20) and the fourth output tapered waveguide (21) and the fifth output tapered waveguide (22) is the same, W7 = 6~15μm; the projection lengths of the sixth S-bend waveguide (24) and the seventh S-bend waveguide (25) along the extension line of the second straight waveguide (15) are the same, L 14 =2000~2500μm; the projection lengths of the fifth S-bend waveguide (23) and the eighth S-bend waveguide (26) along the extension line of the second straight waveguide (15) are the same, which is L. 12 =1500~2000μm; the fifth input tapered waveguide (27), the sixth input tapered waveguide (28), the seventh input tapered waveguide (29) and the eighth input tapered waveguide (30) have the same length L. 13 =50~100μm, the width at the connection of the fifth input tapered waveguide (27), the sixth input tapered waveguide (28) and the third multimode interference waveguide (31) and the width at the connection of the seventh input tapered waveguide (29), the eighth input tapered waveguide (30) and the fourth multimode interference waveguide (32) are the same, W8 = 5~10μm; the length of the third multimode interference waveguide (31) and the fourth multimode interference waveguide (32) is the same, L. 15 =1500~2000μm, with the same width W9 =25~30μm; the width at the connection between the third multimode interference waveguide (31) and the sixth output tapered waveguide (33), the eighth output tapered waveguide (35) and the fourth multimode interference waveguide (32) and the ninth output tapered waveguide (36), the eleventh output tapered waveguide (38) are the same, W 10 =5~15μm; the width W at the connection between the third multimode interference waveguide (31) and the seventh output tapered waveguide (34) 11 =5~15μm; the width W at the connection between the fourth multimode interference waveguide (32) and the tenth output tapered waveguide (37) 11 =5~15μm; W 11 <W 10 The sixth output tapered waveguide (33), the seventh output tapered waveguide (34), the eighth output tapered waveguide (35), the ninth output tapered waveguide (36), the tenth output tapered waveguide (37), and the eleventh output tapered waveguide (38) have the same length L. 16 =50~100μm; The projected lengths of the ninth S-bent waveguide (39), tenth S-bent waveguide (41), eleventh S-bent waveguide (42), and twelfth S-bent waveguide (44) along the fifth straight waveguide (40) and sixth straight waveguide (43) are the same as the lengths of the fifth straight waveguide (40) and sixth straight waveguide (43), which is L. 17 =1500~2000μm; the first output straight waveguide (45), the second output straight waveguide (46), the third output straight waveguide (47), the fourth output straight waveguide (48), the fifth output straight waveguide (49), and the sixth output straight waveguide (50) have the same length L. 18 =500~2000μm.

4. A multi-channel optical power divider based on an MMI structure as described in claim 1, characterized in that: The thickness of the silicon substrate (51) is 0.5-1 mm, the thickness of the polymer lower cladding (52) is 1-8 μm, the thickness of the polymer waveguide core layer (53) is 1-10 μm, and the thickness of the polymer upper cladding (54) above the polymer waveguide core layer is 1-8 μm.

5. A multi-channel optical power divider based on an MMI structure as described in claim 1, characterized in that: The polymer lower cladding (52) and polymer upper cladding (54) are made of one of polycarbonate, polyimide, polymethyl methacrylate, polyethylene, polyester, polystyrene, or EpoClad; the polymer optical waveguide core (53) is made of one of EpoCore, SU-8=2002, or SU-8=2005.

6. A method for fabricating a multi-channel optical power divider based on an MMI structure according to any one of claims 1 to 5, comprising the following steps: A: Cleaning of silicon wafer substrates First, wipe the silicon substrate (51) repeatedly with a cotton ball soaked in acetone, then wipe the silicon substrate (51) vigorously with a cotton ball soaked in ethanol. After wiping it clean, rinse it repeatedly with deionized water. Finally, blow the silicon substrate (51) dry with nitrogen gas, and then put it into a clean petri dish and seal it for storage. B: Fabrication of the polymer waveguide underlayer (52) The polymer undercoating material was spin-coated onto one side surface of a cleaned silicon wafer substrate (51) using a spin-coating process. The spin-coating speed was 1000–5000 rpm. After spin-coating, the substrate was baked at 100°C–150°C for 3–60 minutes. C: Fabrication of polymer waveguide core layer (53) The polymer waveguide core material was spin-coated onto the polymer cladding (52) to form a polymer waveguide core film (53'). The spin-coating speed was 1000-5000 rpm. The polymer waveguide core film (53') was pre-baked at 50℃-180℃ for 3-30 minutes, and then allowed to cool naturally to room temperature. The polymer waveguide core film (53') was then subjected to photolithography. The ultraviolet light emitted by the photolithography machine had a wavelength of 350-400 nm. The waveguide mask and the polymer waveguide core (53) of the power divider to be prepared had complementary structures. Exposure was performed when the photolithography mask was in close contact with the silicon substrate (51). The exposure time was 4-40 seconds. This ensured that the polymer waveguide core film (53') within the structure of the polymer waveguide core (53) to be prepared was fully exposed. The silicon wafer substrate (51) is exposed to ultraviolet light; the silicon wafer substrate (51) after photolithography is removed from the photolithography machine and baked at 50℃~180℃ for 5~30 minutes. After baking, it is naturally cooled to room temperature; the polymer waveguide core layer film (53') is developed, that is, wet etching is first performed in the developer corresponding to the polymer waveguide core layer material for 10~60 seconds to remove the unexposed non-polymer waveguide core layer structure, leaving only the polymer waveguide core layer structure corresponding to the mask. Then, the developer and the polymer waveguide core layer material remaining on the surface of the silicon wafer substrate (51) are washed away with isopropanol solution. Then, the isopropanol remaining on the surface is rinsed off with deionized water and dried with nitrogen. Finally, the substrate is baked at 120℃~150℃ for 30~60 minutes for post-baking hardening, thereby completing the preparation of the strip-shaped polymer waveguide core layer (53). D: Fabrication of the cladding (54) on the polymer optical waveguide The polymer upper cladding material is spin-coated onto the polymer waveguide core layer (53) and the polymer lower cladding layer (52) using a spin-coating process. The spin-coating speed is 1000 to 5000 rpm. After spin-coating, the material is baked at 120°C to 150°C for 3 to 60 minutes to complete the fabrication of the multi-port input power divider.

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