A graphene-based silicon waveguide polarization filter and its fabrication method

Abstract

This invention discloses a graphene-based silicon waveguide polarization filter, comprising a silicon substrate, a silicon dioxide lower cladding, a silicon waveguide, a polymer waveguide, and a silicon dioxide upper cladding, arranged sequentially; the polymer waveguide contains graphene. The graphene concentration ranges from 0.1 mg / ml to 1 mg / ml. A method for fabricating the graphene-based silicon waveguide polarization filter is also disclosed. First, a silicon dioxide lower cladding is fabricated on the upper surface of the silicon substrate. Then, a silicon thin film is fabricated on the upper surface of the silicon dioxide lower cladding. The silicon thin film is then patterned to form a silicon waveguide. Graphene is incorporated into EPO polymer photoresist, and a graphene-containing polymer waveguide is fabricated on the upper surface of the silicon waveguide. Finally, a silicon dioxide upper cladding is fabricated on the surface of the graphene-containing polymer waveguide. This invention enables precise control and patterning of the position, thickness, and size of the graphene-containing polymer waveguide, making it suitable for the precise and efficient fabrication and widespread application of polarization filters.

Description

Technical Field

[0001] This invention belongs to the field of optical communication and integrated photonic device technology, specifically relating to a graphene-based silicon waveguide polarization filter and its fabrication method. Background Technology

[0002] With the rapid development of integrated photonic systems, the requirements for device size are becoming increasingly stringent. An on-chip polarizer is a filter that can transmit light waves with specific polarization states (transverse electric mode TE or transverse magnetic mode TM) while blocking light waves with other polarization states. In compact on-chip integrated systems, on-chip polarizers are indispensable components and are widely used in on-chip gyroscopes, coherent optical communications, optical signal processing, and sensors.

[0003] For waveguide polarizers, the elimination of transverse electric mode (TE) or transverse magnetic mode (TM) can be achieved through waveguide absorption or through waveguide channels. Existing waveguide polarizers include metal-clad waveguides, birefringent polymer waveguides, and lithium niobate waveguides. Although these polarizers achieve high polarization dependent loss (PDL), this usually comes at the cost of high propagation loss and requires complex buffer layers to achieve bandwidth operation.

[0004] In recent years, graphene materials have attracted widespread attention due to their excellent optical anisotropy and broadband response, and have been used to realize polarization filtering. Graphene materials have advantages such as high-speed response, simple physical mechanism, thermal stability, and chemical stability, making them suitable for optical systems requiring high transmittance. Furthermore, graphene is easy to prepare and process, enabling the fabrication of large-area monolayer films, which makes graphene a promising candidate for the large-scale production and application of polarization filters. However, graphene-based waveguide polarizers still face some challenges. Typically, the graphene layers used to fabricate waveguide polarizers require chemical vapor deposition (CVD) or drop-coating methods. These methods have certain limitations, such as difficulty in achieving precise position control and imaging on integrated devices, and large-area continuous coating.

[0005] Chinese patent application CN110780374A discloses a polarizer based on a graphene / polymer hybrid waveguide structure and its fabrication method. The method uses a silicon wafer as a substrate and organic polymer materials as the cladding and core layers of the optical waveguide, respectively, with a graphene film embedded inside the polymer waveguide. The fabrication method employs a drop-coating technique, where graphene is mixed with deionized water to prepare a solution. This solution is then dropped onto the surface of the waveguide core layer using a dropper, and subsequent steps are taken to remove unwanted components, resulting in a graphene film. However, this drop-coating method relies on the number of drop-coating cycles to achieve precise thickness control. Furthermore, patterning the graphene to exist only on the waveguide surface requires etching to remove the graphene outside the core layer, making the process complex.

[0006] For waveguide polarizers, precise control of the position, thickness, and size of the graphene layer is crucial for achieving optimized parameters such as mode overlap and loss. Research on graphene-based waveguide polarizers is still in its early stages. Summary of the Invention

[0007] In view of the above, the purpose of this invention is to provide a graphene-based silicon waveguide polarization filter and its fabrication method. The method involves mechanically mixing graphene powder into a polymer photoresist to prepare a graphene-containing polymer waveguide. This method enables precise control and patterning of the position, thickness, and size of the graphene-containing polymer waveguide, and is suitable for the precise and efficient fabrication and widespread application of polarization filters.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0009] An embodiment of the present invention provides a graphene-based silicon waveguide polarization filter, comprising a silicon substrate layer, a silicon dioxide lower cladding layer, a silicon waveguide, a polymer waveguide, and a silicon dioxide upper cladding layer arranged sequentially; the polymer waveguide is mixed with graphene.

[0010] Preferably, the graphene is a single-layer or multi-layer graphene powder, which is uniformly distributed in the polymer of the polymer waveguide by mechanical mixing.

[0011] Preferably, the transmittance of the silicon waveguide polarization filter to the transverse magnetic mode is controlled by changing the graphene concentration.

[0012] Preferably, the silicon waveguide is a ridge waveguide with an overall length of 5-20 μm, a non-ridge width of 3-5 μm, a non-ridge thickness of 100-230 nm, a ridge width of 0.5-1 μm, and a ridge thickness of 70-100 nm. The silicon waveguide in a silicon waveguide polarizer serves as a propagation medium for light waves. Through specific design and manufacturing, it enables the confinement, guidance, and transmission of specific light waves. Fabricating the silicon waveguide as a ridge waveguide can improve transmission efficiency and stability, reduce energy loss, and improve the quality of the transmission mode.

[0013] Preferably, the wide side dimension of the polymer waveguide is the same as the ridge width dimension of the ridge waveguide, and its length is less than the overall length of the ridge waveguide. The main function of the polymer waveguide is as a transmission medium for light waves, achieving polarization separation by guiding light waves with different polarization states. It features low loss, high bandwidth, and high reliability. In silicon waveguide polarizers, polymer waveguides are used in combination with silicon waveguides. The silicon waveguide and polymer waveguide can together form an optical control system, where the polymer waveguide is mainly responsible for controlling the light waves, while the silicon waveguide is mainly responsible for the transmission of the light waves. Specifically, the silicon waveguide can serve as a transmission channel for light waves, transmitting light waves from one point to another, while the polymer waveguide can control the polarization state parameters of the light waves, thereby achieving the modulation function of the light waves. The combination of the two can realize the transmission and control of light waves, and the transmission performance of light waves can be optimized by changing the shape and size of the polymer waveguide.

[0014] Preferably, the polymer waveguide contains graphene, wherein the concentration of graphene ranges from 0.1 mg / ml to 1 mg / ml.

[0015] Preferably, the thickness of the upper silicon dioxide cladding is 0.4-1 μm, and the thickness of the lower silicon dioxide cladding is 1-2 μm. The lower and upper silicon dioxide claddings are used to protect the silicon waveguide and the polymer waveguide.

[0016] Preferably, the polymer waveguide is made of EPO polymer, which is also used as a photoresist. The EPO polymer is a polymer comprising 2-methoxy-1-methylethyl acetate, epoxy resin, and acrylate.

[0017] To achieve the above-mentioned objectives, this invention also provides a method for fabricating the graphene-based silicon waveguide polarization filter, comprising the following steps:

[0018] Step 1: A silicon dioxide undercoat is grown on a silicon substrate using chemical vapor deposition or magnetron sputtering.

[0019] Step 2: A silicon thin film is grown on the surface of the silicon dioxide undercoat using chemical vapor deposition.

[0020] Step 3: Coat a layer of photoresist on the surface of the silicon thin film. Through photolithography operations including pre-baking, exposure and development, expose the areas to be etched on both sides of the silicon thin film. Use ICP, IBE or IRE etching equipment to etch the silicon thin film to complete the patterning of the silicon thin film and form a silicon waveguide.

[0021] Step 4: Mix graphene into polymer photoresist and use mechanical means, including stirring or ultrasound, to make the graphene evenly distributed.

[0022] Step 5: Apply a polymer photoresist uniformly mixed with graphene to the surface of the silicon waveguide, and form a polymer waveguide through photolithography, exposure and development operations.

[0023] Step 6: Use chemical vapor deposition or magnetron sputtering to grow a silicon dioxide cladding layer on the surface of the polymer waveguide.

[0024] Preferably, the polymer photoresist is an EPO polymer photoresist.

[0025] Compared with the prior art, the beneficial effects of the present invention include at least the following:

[0026] (1) This invention utilizes the optical anisotropy of graphene, which has different transmittance for TE and TM modes, to achieve a polarization filtering effect that effectively filters out the TM mode and allows the TE mode to pass through in the input TEM wavelength. By uniformly mixing graphene powder into EPO polymer photoresist that can be used as a polymer waveguide, and then transferring it to the upper layer of a silicon waveguide using photolithography, it is possible to achieve precise control over the position, thickness, and size of the polymer waveguide with graphene.

[0027] (2) The polarization filter of the present invention has the characteristics of compact structure, wide bandwidth filtering and high extinction ratio, and has potential economic and application value. It is expected to be widely used in the fields of optical communication and integrated photonic device technology. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of a graphene-based silicon waveguide polarization filter structure provided in an embodiment of the present invention.

[0030] Figure 2 This is a schematic diagram of the cross-sectional structure of a graphene-based silicon waveguide polarization filter provided in an embodiment of the present invention.

[0031] Figure 3 This is a schematic diagram of the ridge waveguide dimensions of a graphene-based silicon waveguide polarization filter provided in an embodiment of the present invention.

[0032] Figure 4 This is a schematic diagram of the TE and TM mode transmittance of the polarization filter provided in Comparative Example 1 of the present invention when no graphene is incorporated into the EPO polymer waveguide.

[0033] Figure 5 This is a schematic diagram of the TE mode and TM mode transmittance of the polarization filter provided in Embodiment 1 of the present invention when the imaginary part of the refractive index of the graphene-containing EPO polymer waveguide is 0.05.

[0034] Figure 6 This is a schematic diagram of the transmittance of the TE mode and TM mode of the polarization filter provided in Embodiment 2 of the present invention when the imaginary part of the refractive index of the graphene-containing EPO polymer waveguide is 0.1.

[0035] Figure 7 This is a flowchart of a method for fabricating a graphene-based silicon waveguide polarization filter according to an embodiment of the present invention.

[0036] Explanation of reference numerals in the attached figures:

[0037] 1. Silicon substrate; 2. Lower silicon dioxide cladding; 3. Silicon waveguide; 4. Polymer waveguide; 5. Upper silicon dioxide cladding. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of protection of this invention.

[0039] The inventive concept of this invention is as follows: Addressing the problem of precise control over the position, thickness, and size of the graphene layer in traditional waveguide polarizer fabrication processes, this invention provides a graphene-based silicon waveguide polarization filter and its fabrication method. By designing a special filter, graphene is uniformly distributed in a polymer photoresist using mechanical mixing. The graphene is then transferred to the polymer waveguide layer on top of the silicon waveguide through photolithography processes such as spin coating and development to achieve polarization filtering, effectively filtering out transverse magnetic modes (TM modes). The fabrication process is simple, improving filter efficiency while solving the problem of precise control and patterning of the graphene-containing polymer waveguide, achieving more efficient and precise optical control, and improving optical performance and stability.

[0040] Figure 1 This is a schematic diagram of a graphene-based silicon waveguide polarization filter structure provided in an embodiment of the present invention. Figure 2This is a schematic diagram of the cross-sectional structure of a graphene-based silicon waveguide polarization filter provided in an embodiment of the present invention. Figure 1 and Figure 2 As shown, the embodiment provides a graphene-based silicon waveguide polarization filter, including a silicon substrate layer 1, a silicon dioxide lower cladding layer 2, a silicon waveguide 3, a polymer waveguide 4, and a silicon dioxide upper cladding layer 5.

[0041] Specifically, a silicon dioxide lower cladding layer 2 is disposed on the upper surface of the silicon substrate layer 1; a silicon waveguide 3 is disposed on the surface of the silicon dioxide lower cladding layer 2; a polymer waveguide 4 is disposed on the upper surface of the silicon waveguide 3, and graphene is disposed in the polymer waveguide 4, with the graphene mixed in the polymer of the polymer waveguide 4; and a silicon dioxide upper cladding layer 5 is covered on the polymer waveguide 4.

[0042] Specifically, the graphene is a single-layer or multi-layer graphene powder, uniformly distributed in the polymer of the polymer waveguide 4 through mechanical mixing. The graphene is mixed in the polymer of the polymer waveguide 4, and the transmittance of the silicon waveguide polarization filter to the transverse magnetic mode is controlled by changing the graphene concentration. The graphene concentration range is 0.1 mg / ml to 1 mg / ml.

[0043] Specifically, silicon waveguide 3 is a ridge waveguide, such as... Figure 3 As shown, the overall length L1 is 5-20 μm, the non-ridge width W1 is 3-5 μm, the non-ridge thickness H1 is 100-230 nm, the ridge width W2 is 0.5-1 μm, and the ridge thickness H2 is 70-100 nm.

[0044] Specifically, the wide side dimension of the polymer waveguide 4 is the same as the ridge width dimension of the ridge waveguide, and its length is less than the ridge waveguide length. The polymer waveguide 4 is disposed at the front end, rear end, or any position in between of the silicon waveguide 3. The polymer waveguide 4 is made of EPO polymer, which is also used as a photoresist. The EPO polymer is a polymer comprising 2-methoxy-1-methylethyl acetate, epoxy resin, and acrylate.

[0045] Specifically, the silicon dioxide upper cladding 5 has a thickness of 0.4-1 μm, and the silicon dioxide lower cladding 2 has a thickness of 1-2 μm, which are used to protect the silicon waveguide 3 and the polymer waveguide 4.

[0046] Figure 7 This is a flowchart illustrating a method for fabricating a graphene-based silicon waveguide polarization filter according to an embodiment of the present invention. Figure 7 As shown, the embodiment provides a method for fabricating the above-mentioned graphene-based silicon waveguide polarization filter, including the following steps:

[0047] S1, a silicon dioxide undercoat 2 is prepared on the upper surface of the silicon substrate 1.

[0048] Specifically, a silicon dioxide underlayer 2 is grown on a silicon substrate 1 using chemical vapor deposition or magnetron sputtering.

[0049] S2, a silicon thin film layer is prepared on the upper surface of the silicon dioxide undercoat 2.

[0050] Specifically, a silicon thin film is grown on the surface of the silicon dioxide undercoat 2 using chemical vapor deposition.

[0051] S3, patterning the silicon thin film layer to form a silicon waveguide 3.

[0052] Specifically, a layer of photoresist is coated on the surface of a silicon thin film. Through photolithography operations including pre-baking, exposure and development, the areas to be etched on both sides of the silicon thin film are exposed. The silicon thin film is then etched using ICP, IBE or IRE etching equipment to complete the patterning of the silicon thin film and form a silicon waveguide 3, which is a ridge waveguide.

[0053] S4, graphene is mixed into the polymer photoresist.

[0054] Specifically, graphene is mixed into EPO polymer photoresist, and the graphene is uniformly distributed by mechanical means, including stirring or ultrasound.

[0055] S5, a polymer waveguide 4 mixed with graphene is prepared on the upper surface of silicon waveguide 3.

[0056] Specifically, EPO polymer photoresist uniformly mixed with graphene is coated onto the surface of the ridge waveguide, and EPO polymer waveguide 4 is formed through photolithography, exposure and development operations.

[0057] S6, a silicon dioxide top cladding is prepared on the surface of the polymer waveguide 4 mixed with graphene.

[0058] Specifically, a silicon dioxide cladding 5 is grown on the surface of the EPO polymer waveguide 4 using chemical vapor deposition or magnetron sputtering. The silicon dioxide cladding 5 is tightly bonded to the portion of the ridge waveguide not covered by the EPO polymer waveguide 4.

[0059] It should be noted that, in this embodiment of the invention, the primary objective of the silicon waveguide polarizer is to eliminate TM-mode light while allowing TE-mode light to pass through. This is because the anisotropy of graphene causes TE-mode and TM-mode light to have different propagation characteristics when passing through the silicon waveguide. A silicon waveguide polarizer is a device used to control and adjust the polarization state of light waves. In a silicon waveguide, the propagation of light is affected by material properties, including its refractive index, absorption, and scattering.

[0060] The working principle of polarizers is mainly based on the difference in response to light with different polarization states. In hybrid waveguides composed of silicon and polymer waveguides, transverse electric mode (TE mode) and transverse magnetic mode (TM mode) optical modes have different characteristics. Due to the presence of graphene in the polymer waveguide, the TE mode has lower attenuation when propagating in the silicon waveguide, while the TM mode has higher attenuation. Therefore, when light passes through the silicon waveguide, TM mode light is more easily absorbed, while TE mode light propagates more easily.

[0061] By using silicon waveguide polarizers, light of specific polarization states can be selectively filtered out, such as filtering out TM mode light. This eliminates TM mode while allowing TE mode light to pass through, thereby reducing or eliminating interference or errors caused by the interaction between different polarization states.

[0062] In practical applications, silicon waveguide polarizers can be used in various optical systems that require the elimination or control of the mutual influence of light with different polarization states, such as in optical fiber communication, optical sensing, and optical detection, to improve the performance and stability of the system.

[0063] The effectiveness of the graphene-based silicon waveguide polarization filter prepared in this invention will be explained below with reference to the simulation results of Comparative Example 1, Example 1, and Example 2.

[0064] Comparative Example 1

[0065] A graphene-based silicon waveguide polarization filter includes, from bottom to top, a silicon substrate layer 1, a silicon dioxide lower cladding layer 2, a silicon waveguide 3, an EPO polymer waveguide 4, and a silicon dioxide upper cladding layer, wherein the EPO polymer waveguide 4 is not doped with graphene.

[0066] Among them, silicon waveguide 3 is a ridge waveguide with an overall length L1 of 10 μm, a non-ridge thickness H1 of 150 nm, a non-ridge width W1 of 3 μm, and a ridge width W2 of 0.7 μm. It is fabricated by chemical vapor deposition, photolithography, and etching processes. The ridge thickness, i.e., the etching depth H2, is 70 nm. As a control group, EPO polymer photoresist without graphene doping is patterned on the upper surface of silicon waveguide 3 at the middle position to form EPO polymer waveguide 4 by photolithography. The EPO polymer waveguide 4 has a thickness of 2 μm and a width consistent with the ridge width of the ridge waveguide. In addition, the silicon dioxide upper cladding 5 and the silicon dioxide lower cladding 2, which are used to protect silicon waveguide 3 and polymer waveguide 4, are both fabricated by chemical vapor deposition, with thicknesses of 0.4 μm and 2 μm, respectively.

[0067] A light source with a wavelength of 1500nm-1600nm is coupled into a polarization filter through the front end of silicon waveguide 3 and output from the rear end. Simulation results are as follows: Figure 4 As shown, when the EPO polymer does not contain graphene, the transmittance of the TE mode is 100%, and the transmittance of the TM mode is over 86%.

[0068] Example 1

[0069] A graphene-based silicon waveguide polarization filter includes, from bottom to top, a silicon substrate layer 1, a silicon dioxide lower cladding layer 2, a silicon waveguide 3, an EPO polymer waveguide 4, and a silicon dioxide upper cladding layer 5; the EPO polymer waveguide 4 is doped with a certain concentration of graphene, such that the imaginary part of the refractive index of the graphene-containing EPO polymer waveguide 4 is 0.05.

[0070] The silicon waveguide 3 is a ridge waveguide with an overall length L1 of 10 μm, a non-ridge thickness H1 of 150 nm, a non-ridge width W1 of 3 μm, and a ridge width W2 of 0.7 μm. It is fabricated using chemical vapor deposition, photolithography, and etching processes. The ridge thickness, i.e., the etching depth H2, is 70 nm. Using photolithography, graphene-doped EPO polymer photoresist is patterned on the upper surface of the silicon waveguide 3 at the center position to form an EPO polymer waveguide 4. The EPO polymer waveguide 4 has a thickness of 2 μm and a width consistent with the ridge width of the ridge waveguide. The graphene concentration needs to be adjusted so that the imaginary part of the refractive index of the EPO polymer waveguide 4 is exactly equal to 0.05. Furthermore, the silicon dioxide upper cladding 5 and the silicon dioxide lower cladding 2, used to protect the silicon waveguide 3 and the polymer waveguide 4, are both fabricated using chemical vapor deposition, with thicknesses of 0.4 μm and 2 μm, respectively.

[0071] A light source with a wavelength of 1500nm-1600nm is coupled into a polarization filter through the front end of silicon waveguide 3 and output from the rear end. Simulation results are as follows: Figure 5 As shown, when the imaginary part of the refractive index of the graphene-doped EPO polymer waveguide 4 is equal to 0.05, the polarization filter absorbs the TM mode much more than the TE mode. The transmittance of the TE mode is above 83%, while the transmittance of the TM mode is below 20%.

[0072] Example 2

[0073] A graphene-based silicon waveguide polarization filter includes, from bottom to top, a silicon substrate layer 1, a silicon dioxide lower cladding layer 2, a silicon waveguide 3, an EPO polymer waveguide 4, and a silicon dioxide upper cladding layer 5. The EPO polymer waveguide 4 is doped with a certain concentration of graphene, such that the imaginary part of the refractive index of the graphene-containing EPO polymer waveguide 4 is 0.1.

[0074] The silicon waveguide 3 is a ridge waveguide with a length L1 of 10 μm, a non-ridge thickness H1 of 150 nm, a non-ridge width W1 of 3 μm, and a ridge width W2 of 0.7 μm. It is fabricated using chemical vapor deposition, photolithography, and etching processes. The ridge thickness, i.e., the etching depth H2, is 70 nm. Using photolithography, graphene-doped EPO polymer photoresist is patterned on the upper surface of the silicon waveguide 3 at the center position to form an EPO polymer waveguide 4. The EPO polymer waveguide 4 has a thickness of 2 μm and a width consistent with the ridge width of the ridge waveguide. The graphene concentration needs to be adjusted so that the imaginary part of the refractive index of the EPO polymer waveguide 4 is exactly equal to 0.1. Furthermore, the silicon dioxide upper cladding 5 and the silicon dioxide lower cladding 2, used to protect the silicon waveguide 3 and the polymer waveguide 4, are both fabricated using chemical vapor deposition, with thicknesses of 0.4 μm and 2 μm, respectively.

[0075] A light source with a wavelength of 1500nm-1600nm is coupled into a polarization filter through the front end of silicon waveguide 3 and output from the rear end. Simulation results are as follows: Figure 6 As shown, when the imaginary part of the refractive index of the graphene-doped EPO polymer waveguide 4 is equal to 0.1, the absorption of the TM mode by the polarization filter further increases, the transmittance of the TE mode is about 70%, and the transmittance of the TM mode decreases to below 0.03%.

[0076] In summary, the graphene-based silicon waveguide polarization filter prepared using the method provided in this invention utilizes the optical anisotropy of graphene, which exhibits different transmittance for TE and TM modes, to achieve a polarization filtering effect that effectively filters out the TM mode while allowing the TE mode to pass through in the input TEM wavelength. This invention provides a graphene-based silicon waveguide polarization filter, which, combined with the preparation method provided, mixes graphene powder into an EPO polymer photoresist via mechanical mixing, achieving controllable graphene concentration. Furthermore, since the graphene is mixed into the EPO polymer, which also functions as a photoresist, photolithography can be used to pattern the graphene-containing EPO polymer with precise thickness control. This simplifies the preparation process by eliminating the need for complex subsequent steps, thus possessing potential economic and application value and being suitable for the precise and efficient preparation and widespread application of polarization filters.

[0077] The specific embodiments described above illustrate the technical solution and beneficial effects of the present invention in detail. It should be understood that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A graphene-based silicon waveguide polarization filter, characterized in that, It includes a silicon substrate layer, a silicon dioxide lower cladding layer, a silicon waveguide, a polymer waveguide, and a silicon dioxide upper cladding layer arranged sequentially; the polymer waveguide contains graphene. The silicon waveguide is a ridge waveguide with an overall length of 5-20 μm, a non-ridge width of 3-5 μm, a non-ridge thickness of 100-230 nm, a ridge width of 0.5-1 μm, and a ridge thickness of 70-100 nm, in order to improve transmission efficiency and stability, reduce energy loss, and improve the quality of transmission modes. The silicon waveguide and polymer waveguide together constitute an optical control system. The polymer waveguide is mainly responsible for controlling the light wave, while the silicon waveguide is mainly responsible for the transmission of the light wave. The wide side dimension of the polymer waveguide is the same as the ridge width dimension of the ridge waveguide, and its length is less than the overall length of the ridge waveguide, so as to optimize the transmission performance of the light wave.

2. The graphene-based silicon waveguide polarization filter according to claim 1, characterized in that, The graphene is a single-layer or multi-layer graphene powder, which is uniformly distributed in the polymer of the polymer waveguide by mechanical mixing.

3. The graphene-based silicon waveguide polarization filter according to claim 1, characterized in that, The transmittance of the silicon waveguide polarization filter to the transverse magnetic mode can be controlled by changing the graphene concentration.

4. The graphene-based silicon waveguide polarization filter according to claim 1, characterized in that, The polymer waveguide contains graphene, wherein the concentration of graphene ranges from 0.1 mg / ml to 1 mg / ml.

5. The graphene-based silicon waveguide polarization filter according to claim 1, characterized in that, The upper cladding layer of silicon dioxide has a thickness of 0.4-1 μm, and the lower cladding layer of silicon dioxide has a thickness of 1-2 μm, which are used to protect the silicon waveguide and the polymer waveguide.

6. The graphene-based silicon waveguide polarization filter according to any one of claims 1-5, characterized in that, The polymer waveguide is made of EPO polymer, which is also used as a photoresist. The EPO polymer is a polymer comprising 2-methoxy-1-methylethyl acetate, epoxy resin, and acrylate.

7. A method for fabricating a graphene-based silicon waveguide polarization filter according to any one of claims 1-6, characterized in that, Includes the following steps: Step 1: A silicon dioxide undercoat is grown on a silicon substrate using chemical vapor deposition or magnetron sputtering. Step 2: A silicon thin film is grown on the surface of the silicon dioxide undercoat using chemical vapor deposition. Step 3: Coat a layer of photoresist on the surface of the silicon thin film. Through photolithography operations including pre-baking, exposure and development, expose the areas to be etched on both sides of the silicon thin film. Use ICP, IBE or IRE etching equipment to etch the silicon thin film to complete the patterning of the silicon thin film and form a silicon waveguide. Step 4: Mix graphene into polymer photoresist and use mechanical means, including stirring or ultrasound, to make the graphene evenly distributed. Step 5: Apply a polymer photoresist uniformly mixed with graphene to the surface of the silicon waveguide, and form a polymer waveguide through photolithography, exposure and development operations. Step 6: Use chemical vapor deposition or magnetron sputtering to grow a silicon dioxide cladding layer on the surface of the polymer waveguide.

8. The method for fabricating a graphene-based silicon waveguide polarization filter according to claim 7, characterized in that, The polymer photoresist is an EPO polymer photoresist.

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