A short tube carbon nanotube nanomembrane-based hybrid waveguide filter and a preparation method thereof

Abstract

The application discloses a kind of short tube carbon nanotube nanometer membrane-based hybrid waveguide filter and preparation method thereof, comprising: single-mode optical fiber, straight waveguide, micro-ring waveguide and short tube carbon nanotube nanometer film;Single-mode optical fiber includes a fiber end face, and single-mode optical fiber is used to receive resonant enhanced optical signal, and output;Straight waveguide is arranged on the fiber end face, for transmitting optical signal;Micro-ring waveguide is arranged on the fiber end face, and there is a coupling gap between micro-ring waveguide and straight waveguide, micro-ring waveguide selects optical signal passing through straight waveguide according to specific wavelength, and resonant enhances selected optical signal, short tube carbon nanotube nanometer film is coated on micro-ring waveguide, for absorbing heat.The application is used to solve the technical problems, such as lower tuning efficiency of existing optical filter, greater integration difficulty, to achieve the purpose of simpler integration method, broader tuning range and faster response speed compared with existing on-chip tunable filter.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of filter preparation, in particular to a hybrid waveguide filter based on short-tube carbon nanotube nanomembrane and a preparation method thereof. BACKGROUND

[0002] The all-optical micro-ring tunable filter technology is a technology for realizing a tunable filter by using an optical micro-ring resonator device. Unlike traditional microwave integrated circuit technology, the technology uses an optical resonator device to realize the tunability of the filter. The all-optical micro-ring tunable filter technology is usually composed of a ring-shaped optical waveguide and an optical resonant cavity thereon, and has a resonant characteristic similar to a transmission line. The tunability of the filter can be realized by changing the thermo-optic effect of the optical waveguide or the resonant cavity, thereby changing the resonant frequency and bandwidth.

[0003] With the popularity and development of optical communication, optical filters, as one of the most basic components in optical fiber communication and optical networks, have a huge demand and are widely used. The technical level and production size of optical filters have a direct impact on the development of optical networks. Tunable filters have the advantages of improving the flexibility of optical channels and reducing the operating cost of optical devices.

[0004] Optical filters have developed rapidly in recent years as one of the key devices in wavelength division multiplexing (WDM) optical communication systems and sensing systems. Among them, the use of micro-ring resonators on-chip to make optical filters has gradually become an important application. However, with the increase of application scenarios, the existing optical filters gradually expose many shortcomings, such as difficulty in on-chip integration, difficulty in tuning, poor stability, high noise, and low tuning efficiency under high power conditions. SUMMARY

[0005] In order to overcome the shortcomings of the prior art, the present application provides a hybrid waveguide filter based on short-tube carbon nanotube nanomembrane and a preparation method thereof, which solves the technical problems of low tuning efficiency and high integration difficulty of existing optical filters, so as to achieve the purpose of having a simpler integration method, a wider tuning range and a faster response speed compared with existing on-chip tunable filters.

[0006] To solve the above problems, the technical scheme adopted by the present application is as follows:

[0007] A hybrid waveguide filter based on short-tube carbon nanotube nanomembrane, comprising:

[0008] A single-mode optical fiber comprising an optical fiber end face, the single-mode optical fiber being used to receive a resonantly enhanced optical signal and output the optical signal;

[0009] A straight waveguide disposed on the optical fiber end face and used to transmit an optical signal;

[0010] The micro-ring waveguide is coated with a short-tube carbon nanotube nanofilm for absorbing heat.

[0011] As a preferred embodiment of the present application, the short-tube carbon nanotube nanofilm is coated on the surface of the half micro-ring waveguide of the micro-ring waveguide away from the straight waveguide.

[0012] As a preferred embodiment of the present application, the straight waveguide comprises an input end for receiving the optical signal and an output end for outputting the optical signal.

[0013] As a preferred embodiment of the present application, the micro-ring waveguide and the straight waveguide form a coupling region based on the coupling gap, when the optical signal enters the coupling region from the input end of the straight waveguide, the optical signal of the specific wavelength is coupled to the micro-ring waveguide and propagates along the micro-ring waveguide, and the remaining optical signal is output from the output end of the straight waveguide.

[0014] As a preferred embodiment of the present application, the micro-ring waveguide comprises a ring cavity, and the optical signal of the specific wavelength generates resonance enhancement in the ring cavity after propagating along the micro-ring waveguide for one round.

[0015] As a preferred embodiment of the present application, the height and width of the straight waveguide are 3-5 μm, and the height and width of the micro-ring waveguide are consistent with those of the straight waveguide.

[0016] As a preferred embodiment of the present application, the inner diameter of the micro-ring waveguide is 13-17 μm, and the outer diameter is 16-20 μm.

[0017] As a preferred embodiment of the present application, the coupling gap is 0.3-0.5 μm.

[0018] A preparation method of a hybrid waveguide filter based on a short-tube carbon nanotube nanofilm, comprising the following steps:

[0019] A single-mode optical fiber is provided, and the single-mode optical fiber is cut to obtain a smooth optical fiber end face;

[0020] The optical fiber end face is immersed in photoresist, and laser direct writing is performed to manufacture a straight waveguide and a micro-ring waveguide with a coupling gap on the optical fiber end face;

[0021] The straight waveguide and the micro-ring waveguide are cleaned, the straight waveguide and the half micro-ring waveguide close to the straight waveguide are shielded, a short tube carbon nanotube solution is sprayed on the surface of the micro-ring waveguide, a short tube carbon nanotube nanofilm is formed on the surface of the half micro-ring waveguide far from the straight waveguide, and the mixed waveguide filter is obtained.

[0022] As a preferred embodiment of the present application, when the short tube carbon nanotube solution is sprayed on the surface of the micro-ring waveguide, the following steps are included:

[0023] After the short tube carbon nanotube and anhydrous ethanol are preliminarily mixed, ultrasonic oscillation mixing is used to form a short tube carbon nanotube solution with a concentration of 0.001-0.003 mg / ml, and the short tube carbon nanotube solution is vertically sprayed downward at a position 2-3 cm away from the micro-ring waveguide by using a watering can.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] (1) The present application is processed by combining a polymer material with a single-mode fiber end face and a two-photon polymerization process to form a three-dimensional structure. Compared with a traditional on-chip tunable filter, a new integrated process, structure and coating material are used to improve sensitivity and other related performance parameters.

[0026] (2) Compared with the existing on-chip tunable filter, the present application has a simpler integrated method, a wider tuning range and a faster response speed, overcomes the shortcomings of the existing on-chip tunable filter, such as low efficiency and great difficulty in integration, and meets the application of the tunable filter in the field of all-optical control.

[0027] (3) By improving the structure of the micro-ring waveguide (resonator) and the thickness of the short tube carbon nanotube, the structure of the present application can effectively increase the spectral tuning range and the response speed of the device. In addition, the two-photon polymerization process can be used to more quickly and simply process the device, so that the device has higher precision and sensitivity.

[0028] The present application will be further described in detail below in combination with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 - is a structure schematic diagram of the mixed waveguide filter of the embodiment of the present application;

[0030] Figure 2 - is a structure schematic diagram of the micro-ring waveguide and the straight waveguide of the embodiment of the present application;

[0031] Figure 3 - is a preparation process schematic diagram of the mixed waveguide filter of the embodiment of the present application;

[0032] Figure 4 - This is the transmission spectrum of the hybrid waveguide filter in the 0-18mW 980nm pump laser range at room temperature according to an embodiment of the present invention.

[0033] Figure 5 - is a linear relationship graph between pump power and wavelength shift in an embodiment of the present invention;

[0034] Figure 6 - This is the transmission spectrum of the hybrid waveguide filter in the temperature range of 24℃ to 26.5℃ according to an embodiment of the present invention;

[0035] Figure 7 - is a linear relationship graph between temperature change and wavelength shift in an embodiment of the present invention;

[0036] Figure 8 - is a physical diagram of the hybrid waveguide filter according to an embodiment of the present invention;

[0037] Figure 9 - This is a step diagram illustrating the fabrication method of a hybrid waveguide filter based on short-tube carbon nanotube nanofilm according to an embodiment of the present invention.

[0038] Explanation of reference numerals: 1. Single-mode fiber; 2. Straight waveguide; 3. Micro-ring waveguide; 4. Fiber end face; 5. Short carbon nanotube nanofilm; 6. Coupling gap; 7. Input end; 8. Output end; 9. Coupling region; 10. Three-dimensional displacement platform; 11. Objective lens; 12. Glass slide; 13. Photoresist; 14. Fiber fixing tube. Detailed Implementation

[0039] The hybrid waveguide filter based on short-tube carbon nanotube nanofilm provided by this invention, such as... Figure 1 As shown, the structure includes: a single-mode optical fiber 1, a straight waveguide 2, and a micro-ring waveguide 3. The single-mode optical fiber 1 includes an optical fiber end face 4, which is used to receive and output resonantly enhanced optical signals. The straight waveguide 2 is disposed on the optical fiber end face 4 and is used to transmit optical signals. The micro-ring waveguide 3 is disposed on the optical fiber end face 4 and has a coupling gap 6 between it and the straight waveguide 2. The micro-ring waveguide 3 selects the optical signals passing through the straight waveguide 2 according to a specific wavelength and resonates and enhances the selected optical signals. A short-tube carbon nanotube nanofilm 5 is coated on the micro-ring waveguide 3 to absorb heat.

[0040] Furthermore, a short carbon nanotube nanofilm 5 is coated on the surface of the half of the microring waveguide 3 away from the straight waveguide 2.

[0041] Further, the short tube carbon nanotube nanofilm 5 has a thickness of 50-100 nm. By comparing the transmission spectrum simulated by FDTD simulation, when the thickness of the short tube carbon nanotube nanofilm 5 is in the range of 0-50 nm, the extinction ratio of the transmission spectrum increases with the increase of the thickness. When the thickness of the short tube carbon nanotube nanofilm 5 is in the range of 50-100 nm, the transmission spectrum hardly changes. Considering the loss and the ease of operation, in the actual film plating, the short tube carbon nanotube nanofilm 5 is coated on the surface of the half micro-ring waveguide 3 away from the straight waveguide 2, and the thickness is 50-100 nm.

[0042] Further, the short tube carbon nanotube nanofilm 5 coated on the surface of the micro-ring waveguide 3 has good light absorption characteristics and excellent light-heat conversion efficiency, so as to absorb a large amount of heat, improve the thermo-optic effect of the filter, and improve the tuning effect of the filter.

[0043] Further, the straight waveguide 2 includes an input end 7 and an output end 8, the input end 7 is used to receive the optical signal, and the output end 8 is used to output the optical signal.

[0044] Further, the micro-ring waveguide 3 and the straight waveguide 2 form a coupling region 9 based on the coupling gap 6. When the optical signal enters the coupling region 9 from the input end 7 of the straight waveguide 2, the optical signal of a specific wavelength will be coupled to the micro-ring waveguide 3 and propagate along the micro-ring waveguide 3, and the remaining optical signal will be output from the output end 8 of the straight waveguide 2.

[0045] Figure 2 is a structural schematic diagram of the micro-ring waveguide 3 and the straight waveguide 2, wherein Figure 2 As can be seen, there is a coupling gap 6 between the micro-ring waveguide 3 and the straight waveguide 2, and there is a coupling region 9 centered on the coupling gap 6. When the optical signal enters from the input end 7 of the straight waveguide 2, it will inevitably pass through the coupling region 9 during propagation on the straight waveguide 2, thereby effectively filtering the optical signal.

[0046] Further, the micro-ring waveguide 3 includes a ring cavity, and the optical signal of a specific wavelength will produce resonance enhancement in the ring cavity after propagating along the micro-ring waveguide 3 for one round.

[0047] Further, the optical signal of a specific wavelength must satisfy the following condition: the light coupled to the micro-ring waveguide 3 will produce an optical signal with a phase difference of 2π integer times after propagating along the micro-ring waveguide 3 for one round, at which time resonance enhancement will occur in the ring cavity. The light that does not satisfy this condition will be directly output from the output end of the straight waveguide 2 because it cannot resonate in the ring cavity.

[0048] Further, the height and width of the straight waveguide 2 are 3-5 μm, and the height and width of the micro-ring waveguide 3 are consistent with those of the straight waveguide 2. The height and width of the micro-ring waveguide 3 need to be consistent with those of the straight waveguide 2 to ensure the matching and coupling efficiency therebetween. If the height and width are inconsistent, there will be a large loss and reflection of the optical signal in the transmission process, thereby affecting the performance and sensitivity of the micro-ring waveguide 3 (resonator).

[0049] Further, the length of the straight waveguide 2 is 100-120 μm, and the straight waveguide has the best coupling effect under the above length, width and height parameters, and the transmission spectrum obtained by the actual experiment is the best.

[0050] Further, the inner diameter of the micro-ring waveguide 3 is 13-17 μm, and the outer diameter is 16-20 μm. If the radius of the micro-ring waveguide 3 is too large, the free spectral range (FSR) will be too small, thereby limiting the working wavelength range of the filter. However, if the radius of the micro-ring waveguide 3 is too small, the bending loss of the filter will be increased. Considering the above two factors and after actual experiment comparison, when the inner diameter of the micro-ring waveguide 3 is 13-17 μm and the outer diameter is 16-20 μm, the transmission spectrum obtained is the best.

[0051] Further, the coupling gap 6 is 0.3-0.5 μm. The coupling gap 6 is an important factor for controlling the transmission and coupling strength of the optical signal between the straight waveguide 2 and the micro-ring waveguide 3. If there is no coupling gap 6, the coupling strength of the optical signal cannot be controlled, which will cause the micro-ring waveguide 3 (resonator) to lose the resonant characteristics and the performance to be unstable. Generally, as the coupling gap 6 increases, the coupling between the micro-ring waveguide 3 and the straight waveguide 2 becomes weaker, and the influence on the transmission and coupling coefficient of the light is smaller, thereby reducing the sensitivity and coupling strength of the micro-ring waveguide 3 (resonator). When the coupling gap 6 between the two waveguides is more than 0.5 μm, the coupling effect therebetween cannot meet the requirements, and therefore the coupling gap 6 needs to be controlled within 0.5 μm. However, when the filter is actually 3D double-photon printed, due to the error, when the coupling gap 6 between the two waveguides is less than 0.3 μm, the straight waveguide 2 and the micro-ring waveguide 3 will be connected together, thereby causing the coupling gap 6 to disappear, and therefore the coupling gap 6 is selected to be 0.3-0.5 μm.

[0052] In summary, the principle of the present application is as follows:

[0053] The micro-ring waveguide 3 (resonator) is wavelength-selective; only light of a specific wavelength can resonate within the ring cavity of the micro-ring waveguide 3. The optical signal is input to the coupling region 9 through the straight waveguide 2. A small portion of the optical signal in the straight waveguide 2 couples to the micro-ring waveguide 3 and continues to propagate along it. The remaining optical signal is output directly through the output terminal 7 of the straight waveguide 2. If the optical wave coupled to the ring waveguide 3 propagates around the micro-ring waveguide 3 and generates an optical signal with a phase difference that is an integer multiple of 2π, resonance enhancement will occur within the ring cavity. The optical signal satisfying this condition is the one that couples to the micro-ring waveguide 3. Optical signals that do not satisfy the above condition cannot resonate and enhance within the micro-ring waveguide 3 (resonator) and are directly output from the output terminal 8 of the straight waveguide 2.

[0054] The method for fabricating a hybrid waveguide filter based on short-tube carbon nanotube nanofilms provided by this invention, such as... Figure 9 As shown, it includes the following steps:

[0055] Step S1: Provide a single-mode fiber 1 and cut the single-mode fiber 1 to obtain a smooth fiber end face 4.

[0056] Step S2: Immerse the fiber end face 4 in photoresist 13 and perform laser direct writing to fabricate a straight waveguide 2 and a micro-ring waveguide 3 with coupling gap 6 on the fiber end face 4.

[0057] Step S3: Clean the straight waveguide 2 and the micro-ring waveguide 3. After shielding the straight waveguide 2 and the half of the micro-ring waveguide 3 close to the straight waveguide 2, spray a short carbon nanotube solution onto the surface of the micro-ring waveguide 3. Form a short carbon nanotube nanofilm 5 on the surface of the half of the micro-ring waveguide 3 away from the straight waveguide 2 to obtain a hybrid waveguide filter.

[0058] In step S1 above, the cutting of single-mode fiber 1 is specifically performed by using a fiber optic cleaver to directly cut the single-mode fiber 1 to obtain a smooth fiber end face 4.

[0059] In step S2 above, as Figure 3 As shown, immersing the fiber end face 4 in the photoresist 13 specifically involves fixing the single-mode fiber 1 to the three-dimensional displacement platform 10 via the fiber fixing tube 14, so that the smooth fiber end face 4 faces downward. The fiber fixing tube 14 is moved by controlling the three-dimensional displacement platform 10 to directly immerse the smooth fiber end face 4 into the photoresist 13.

[0060] In step S2 above, as Figure 3As shown, the laser direct writing is specifically as follows: the core layer of the single-mode optical fiber 1 is aligned with the picosecond pulse laser by using the three-dimensional displacement platform 10 and the objective lens 11, then the single-mode optical fiber 1 is directly subjected to laser direct writing by using the picosecond laser with a wavelength of about 532 nm, the laser focus point on the fiber end face 4 moves in the photoresist 13, the positions passed through induce the photoresist 13 to occur a two-photon polymerization reaction to be solidified, and the straight waveguide 2 and the micro-ring waveguide 3 with the coupling gap 6 are manufactured on the fiber end face 4, and the processing time is 9-12 minutes.

[0061] In the step S3, the straight waveguide 2 and the micro-ring waveguide 3 are cleaned specifically as follows: after the processing is completed, the single-mode optical fiber 1 is lifted by using the three-dimensional displacement platform 10, the single-mode optical fiber 1 is taken out from the optical fiber fixing tube 14, and the straight waveguide 2 and the micro-ring waveguide 3 are cleaned by using anhydrous ethanol for 1-2 minutes.

[0062] In the step S3, the shielding is specifically as follows: the single-mode optical fiber 1 is fixed on the optical moving platform, the glass slide 12 is placed on the optical moving platform by using a clamp, the glass slide 12 is moved to a position 1-2 cm above the micro-ring waveguide 3 by using the optical displacement platform, the straight waveguide 2 is shielded with the half micro-ring waveguide 3 close to the straight waveguide 2, and the short tube carbon nanotube solution is prevented from being sprayed on the straight waveguide 2 and the half micro-ring waveguide 3 close to the straight waveguide, and the remaining half micro-ring waveguide 3 is exposed outside.

[0063] In the step S3, when the short tube carbon nanotube solution is sprayed on the surface of the micro-ring waveguide 3, the following steps are included.

[0064] After the short tube carbon nanotube and the anhydrous ethanol are preliminarily mixed, the ultrasonic wave is used for oscillation mixing to form the short tube carbon nanotube solution with a concentration of 0.001-0.003 mg / ml, and the short tube carbon nanotube solution is vertically sprayed at a position 2-3 cm away from the micro-ring waveguide 2 by using a watering can.

[0065] Preferably, the oscillation mixing time is 20-30 min, and the concentration of the short tube carbon nanotube solution is 0.002 mg / ml. The short tube carbon nanotube solution at the concentration is convenient to control, and can form the uniform short tube carbon nanotube nanofilm 5 on the surface of the micro-ring waveguide 3.

[0066] The following examples are further illustrations of the present application, but the scope of the present application is not limited thereto.

[0067] Example

[0068] The common single-mode optical fiber of Corning is selected, the diameter of the single-mode optical fiber 1 is 125 μm; the height of the straight waveguide 2 is 5 μm, the length is 120 μm, and the width is 3 μm; the height of the micro-ring waveguide 3 is 5 μm, the width is 3 μm, the inner diameter and the outer diameter are 15 μm and 18 μm respectively; and the coupling gap 6 between the two waveguides is 0.4 μm. The short-tube carbon nanotube solution is sprayed on the half micro-ring waveguide 3 away from the straight waveguide 2 to form a short-tube carbon nanotube nanofilm 5 with a thickness of 50.62 nm, and the mixed waveguide filter of the embodiment is formed, as shown in Figure 8 .

[0069] Figure 4 is a transmission spectrum diagram of the mixed waveguide filter at room temperature in the range of 0-18 mW of 980 nm pump laser, and it can be seen from Figure 4 that the transmission spectrum is blue-shifted with the increase of the pump light power, which indicates that the filter of the present application can realize the function of tunable and has good all-optical control characteristics.

[0070] Figure 5 is a linear relationship diagram of the pump power and the wavelength shift, and it can be seen from Figure 5 that the tuning range of the wavelength is 0.45 nm, and the tuning efficiency is -0.030 nm / mW. It can be seen from Figure 4 and Figure 5 that in the range of 0-18 mW of the pump power, the wavelength tuning of the mixed waveguide filter shows a good quasi-linear relationship, which indicates that the transmission spectrum characteristics of the mixed waveguide filter can be adjusted by changing the pump light power, so as to realize the tunable function of the mixed waveguide filter.

[0071] Figure 6 is a transmission spectrum diagram of the mixed waveguide filter in the temperature range of 24-26.5℃, and it can be seen from Figure 6 that the transmission spectrum of the mixed waveguide filter is blue-shifted with the increase of the temperature. Figure 7 is a linear relationship diagram of the temperature change and the wavelength shift, and it can be seen from Figure 7 that the temperature sensitivity is -1.927 nm / ℃. It can be seen from Figure 6 and Figure 7 that in the temperature range of 24-26.5℃, the mixed waveguide filter shows a good quasi-linear relationship, which indicates that the transmission spectrum characteristics of the mixed waveguide filter can be adjusted by changing the temperature.

[0072] Compared with the prior art, the present application has the following beneficial effects:

[0073] (1) The present application is combined with the polymer material and the two-photon polymerization process at the end face of the single-mode optical fiber to form a three-dimensional structure, and compared with the traditional on-chip tunable filter, a new integrated process, structure and coating material are adopted, so that the sensitivity and other related performance parameters are improved;

[0074] (2) The tunable filter has a simple integration method, a wide tuning range and a fast response speed compared with the prior art on-chip tunable filter, and overcomes the defects of low efficiency and difficult integration of the prior art on-chip tunable filter, and meets the application of the tunable filter in the full optical control field;

[0075] (3) The tunable filter can effectively increase the spectral tuning range and the response speed of the device by improving the structure of the micro-ring waveguide (resonator) and the thickness of the short tube carbon nanotube, and further changing the structure to regulate light.

[0076] The above-mentioned embodiments are only preferred embodiments of the present application, and cannot be used to limit the protection scope of the present application, and any non-essential changes and substitutions made by those skilled in the art on the basis of the present application shall fall within the scope of the present application.

Claims

1. A hybrid waveguide filter based on short tube carbon nanotube nanomembrane, characterized by, include: A single-mode optical fiber, including an optical fiber end face, is used to receive and output an optical signal that has been resonantly enhanced. A straight waveguide is disposed on the end face of the optical fiber for transmitting optical signals; A microring waveguide is disposed on the end face of the optical fiber and has a coupling gap with the straight waveguide. The microring waveguide selects the optical signal passing through the straight waveguide according to a specific wavelength and resonates and enhances the selected optical signal. A short carbon nanotube nanofilm is coated on the microring waveguide for absorbing heat; wherein, the short carbon nanotube nanofilm is coated on the half of the microring waveguide surface away from the straight waveguide.

2. The short tube carbon nanotube nanomembrane based hybrid waveguide filter of claim 1, wherein, The straight waveguide includes an input terminal and an output terminal. The input terminal is used to receive optical signals, and the output terminal is used to output optical signals.

3. The short tube carbon nanotube nanomembrane based hybrid waveguide filter of claim 2, wherein, The micro-ring waveguide and the straight waveguide form a coupling region based on the coupling gap. When an optical signal enters the coupling region from the input end of the straight waveguide, an optical signal of a specific wavelength will couple to the micro-ring waveguide and propagate along the micro-ring waveguide, while the remaining optical signal will be output from the output end of the straight waveguide.

4. The short tube carbon nanotube nanomembrane based hybrid waveguide filter of claim 3, wherein, The micro-ring waveguide includes a ring cavity. After the optical signal of a specific wavelength propagates along the micro-ring waveguide for one revolution, it generates resonance enhancement in the ring cavity.

5. The short tube carbon nanotube nanomembrane based hybrid waveguide filter according to any one of claims 1-4, wherein, The height and width of the straight waveguide are 3-5 μm, and the height and width of the micro-ring waveguide are consistent with those of the straight waveguide.

6. The short tube carbon nanotube nanomembrane based hybrid waveguide filter according to any one of claims 1-4, wherein, The inner diameter of the micro-ring waveguide is 13-17 μm, and the outer diameter is 16-20 μm.

7. The short tube carbon nanotube nanomembrane based hybrid waveguide filter according to any one of claims 1-4, wherein, The coupling gap is 0.3-0.5 μm.

8. A method of fabricating a hybrid waveguide filter based on short tube carbon nanotube nanomembrane, characterized in that, Includes the following steps: A single-mode optical fiber is provided, and the single-mode optical fiber is cut to obtain a smooth optical fiber end face; The fiber end face is immersed in photoresist and laser direct writing is performed to fabricate a straight waveguide and a micro-ring waveguide with coupling gap on the fiber end face. The straight waveguide and the micro-ring waveguide are cleaned, and the straight waveguide and half of the micro-ring waveguide near the straight waveguide are shielded. Then, a short-tube carbon nanotube solution is sprayed onto the surface of the micro-ring waveguide to form a short-tube carbon nanotube nanofilm on the surface of the half of the micro-ring waveguide away from the straight waveguide, thus obtaining the hybrid waveguide filter.

9. The method of claim 8, wherein the method further comprises: When spraying a short-tube carbon nanotube solution onto the surface of the microring waveguide, the following steps are included: Short carbon nanotubes and anhydrous ethanol are initially mixed and then vibrated and mixed using ultrasound to form a short carbon nanotube solution with a concentration of 0.001-0.003 mg / ml. The short carbon nanotube solution is then sprayed vertically downwards from a distance of 2-3 cm from the micro-ring waveguide using a spray bottle.

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