All-fiber electro-optic modulator and preparation method thereof

Abstract

The present application discloses an all-fiber electro-optic modulator and a preparation method, which relates to the field of optoelectronic devices. The all-fiber electro-optic modulator includes: a single-mode-tapered dual-mode-single-mode structure optical fiber, wherein the single-mode-tapered dual-mode-single-mode structure optical fiber is a single-mode-dual-mode-single-mode structure optical fiber whose dual-mode optical fiber region is tapered to a tapered dual-mode optical fiber; an ITO conductive glass electrode, wherein the ITO conductive glass is a top ITO conductive glass electrode and a bottom ITO conductive glass electrode; the ITO conductive glass electrode is used to connect an external modulation voltage; a polyimide gasket, wherein the polyimide gasket is fixed at both ends of the bottom ITO conductive glass; an organic electro-optic polymer film, wherein the organic electro-optic polymer film is spin-coated on the bottom ITO conductive glass, and the single-mode-tapered dual-mode-single-mode structure optical fiber is placed on the surface of the polarized organic electro-optic polymer film.

Description

Technical Field

[0001] The present application relates to the field of optoelectronic devices, and in particular to an all-fiber electro-optic modulator and a preparation method thereof. Background Art

[0002] With the popularization and application of new technologies such as cloud computing, the Internet of Things, 5G, and artificial intelligence, people's demand for data continues to increase, and thus the demand for optical transmission networks has also grown rapidly. High-speed modulation of optical signals has become a key link in optical transmission systems. Optical fiber communication technology has gradually become the mainstream communication technology due to its advantages such as low loss, large communication capacity, wide bandwidth, and strong anti-electromagnetic interference. With the large-scale application of optical fiber communication technology, higher requirements are placed on the integration and cost control of electro-optical modulation devices.

[0003] Electro-optic modulator is one of the core components of optical fiber communication system, and its performance greatly affects the performance of optical fiber communication system. Lithium niobate waveguide is an ideal material for electro-optic modulator due to its large electro-optic coefficient (30pm / V) and wide electromagnetic wave transmission window (0.35-5μm). Lithium niobate electro-optic modulator based on Mach-Zehnder (MZ) waveguide structure has become the most widely used modulator in existing systems.

[0004] However, the half-wave voltage of lithium niobate waveguide electro-optical modulator is relatively high (2V), and the manufacturing process is extremely demanding, resulting in high cost. In addition, the coupling between planar waveguide and optical fiber will produce large losses when connected to the optical fiber communication system. Summary of the invention

[0005] The main purpose of this application is to provide an all-fiber electro-optic modulator and a preparation method, aiming to solve the technical problems of low modulation efficiency, complex manufacturing process, high cost and difficulty in integration with optical fiber communication systems of planar waveguide modulators in electro-optic modulators.

[0006] In order to solve the above technical problems, the present application proposes: an all-fiber electro-optic modulator, the all-fiber electro-optic modulator comprising:

[0007] Single-mode-tapered dual-mode-single-mode structure optical fiber, wherein the single-mode-tapered dual-mode-single-mode structure optical fiber is a single-mode-dual-mode-single-mode structure optical fiber in which the dual-mode optical fiber region is tapered to form a tapered dual-mode optical fiber;

[0008] ITO conductive glass electrodes, wherein the ITO conductive glass is a top layer ITO conductive glass electrode and a bottom layer ITO conductive glass electrode; the ITO conductive glass electrodes are used to connect an external modulation voltage;

[0009] Polyimide gaskets, the polyimide gaskets are fixed at both ends of the bottom ITO conductive glass;

[0010] An organic electro-optic polymer film is spin-coated on the bottom ITO conductive glass, and the single-mode-tapered dual-mode-single-mode structure optical fiber is placed on the surface of the polarized organic electro-optic polymer film.

[0011] As some optional embodiments of the present application, the single-mode-tapered dual-mode-single-mode structure optical fiber is provided in the horizontal direction in sequence: an import-single-mode optical fiber, a tapered transition zone 1, a tapered flat zone, a tapered transition zone 2 and an export-single-mode optical fiber;

[0012] Wherein, the import-single-mode optical fiber and the export-single-mode optical fiber are single-mode optical fibers with complete structures;

[0013] The optical fiber diameters of the tapered transition zone 1 and the tapered transition zone 2 gradually change along the axial direction;

[0014] The optical fiber diameter in the tapered flat region remains constant along the axial direction.

[0015] As some optional embodiments of the present application, the length of the dual-mode optical fiber in the single-mode-tapered dual-mode-single-mode structure optical fiber is 1 to 100 mm, the diameter of the tapered flat zone is 4 to 40 μm, and the total length of the tapered transition zone 1, the tapered flat zone and the tapered transition zone 2 is 1 to 100 mm;

[0016] The thickness of the polyimide gasket is 2-500 μm; the length of the organic electro-optic polymer film is 1-100 mm, the width is 10-10 mm, and the thickness is 0.5-50 μm.

[0017] In order to solve the above technical problems, the present application also proposes a method for preparing the all-fiber electro-optic modulator as described above, comprising the following steps:

[0018] Prepare the single-mode-tapered dual-mode-single-mode structure optical fiber;

[0019] Prepare the organic electro-optic polymer film, spin-coat the organic electro-optic polymer film on the bottom ITO conductive glass, and polarize it to obtain the polarized organic electro-optic polymer film;

[0020] After integrating the single-mode-tapered dual-mode-single-mode structure optical fiber and the polarized organic electro-optic polymer film, a first film optical fiber is obtained;

[0021] The top layer of ITO conductive glass is placed on the top of the electro-optic modulator, and the top layer of ITO conductive glass and the bottom layer of ITO conductive glass are connected to an external modulation voltage to obtain an all-fiber electro-optic modulator.

[0022] As some optional embodiments of the present application, the steps of preparing the single-mode-tapered dual-mode-single-mode structure optical fiber include:

[0023] The two sections of single-mode optical fiber are fused together with a 2cm long dual-mode optical fiber. The single-mode optical fiber end coating layer and the entire dual-mode optical fiber coating layer are removed using optical fiber strippers, and the optical fiber end is cut flat using an optical fiber cutter. Finally, the single-mode optical fiber is fused to both ends of the dual-mode optical fiber using an optical fiber fusion splicer to form a single-mode-dual-mode-single-mode structure optical fiber.

[0024] The two ends of the single-mode-dual-mode-single-mode structure optical fiber are fixed on the fixture of the optical fiber taper system, and the two ends of the optical fiber are connected to the laser and the spectrometer respectively; the flame of the taper system is ignited, and the length and speed of the taper are set at the same time, and the dual-mode optical fiber region of the single-mode-dual-mode-single-mode structure optical fiber is melt-tapered to produce a single-mode-tapered dual-mode-single-mode structure optical fiber with a tapered region length of 25 mm and a tapered flat region diameter of 10 μm.

[0025] As some optional embodiments of the present application, the steps of preparing the organic electro-optic polymer film, spin-coating the organic electro-optic polymer film on the underlying ITO conductive glass, and polarizing the film to obtain the polarized organic electro-optic polymer film include:

[0026] Disperse Red 1 and polymethyl methacrylate are dissolved in anisole solvent and stirred evenly to obtain an organic electro-optic polymer film;

[0027] Spin coating the organic electro-optic polymer film on the bottom ITO conductive glass to obtain a first film;

[0028] polarizing the first film to obtain a polarized organic electro-optic polymer film;

[0029] Wherein, the mass ratio of the disperse red 1 to polymethyl methacrylate is 1:4; the amount of the anisole solvent is 3 mL; and the stirring time is 36 h.

[0030] As some optional embodiments of the present application, the step of polarizing the first film to obtain a polarized organic electro-optic polymer film includes:

[0031] The first film is heated and cured and then dried to obtain a second film;

[0032] The second film is heated to the glass transition temperature, a voltage is applied for corona poling for 10-30 minutes, the temperature is lowered to room temperature, the polarization electric field is maintained during the cooling period, and the polarization electric field is removed after the cooling is completed to obtain a polarized organic electro-optic polymer film.

[0033] As some optional embodiments of the present application, the polarization temperature is 90-120° C., and the polarization voltage is 1-10 kV.

[0034] As some optional embodiments of the present application, the diameter of the needle electrode tip of the corona polarization needle electrode is 1-10 μm, and the distance from the lower electrode is 1-50 mm.

[0035] As some optional embodiments of the present application, the step of integrating the single-mode-tapered dual-mode-single-mode structure optical fiber and the polarized organic electro-optic polymer film to obtain a first film optical fiber includes:

[0036] Fixing the single-mode-tapered dual-mode-single-mode structure optical fiber on an optical fiber fixture, and moving the translation stage under the optical fiber fixture to make the tapered area of ​​the optical fiber slightly bend downward;

[0037] The polarized organic electro-optic polymer film is fixed on a displacement stage, and the displacement stage is moved until the polarized organic electro-optic polymer film and the single-mode-tapered dual-mode-single-mode structure optical fiber are in contact and integrated to obtain a first film optical fiber.

[0038] Compared with the prior art, the present application has the following beneficial effects: the all-fiber electro-optic modulator described in the present application includes four parts: a single-mode-tapered dual-mode-single-mode structure optical fiber, an electro-optic polymer, an ITO conductive glass, and a polyimide gasket, aiming to improve the modulation efficiency, simplify the preparation process, and reduce the cost, while being able to seamlessly connect with the optical fiber communication system. The large electro-optic coefficient of the organic electro-optic polymer film can effectively improve the modulation efficiency, and its processing technology is simple and low-cost, and the organic electro-optic polymer film can be prepared by a simple method of spin coating. The single-mode-tapered dual-mode-single-mode structure optical fiber has a higher refractive index sensitivity than traditional micro-nano optical fibers and single-mode-tapered dual-mode-single-mode structure optical fibers, which can further increase the modulation efficiency of the device. The single-mode-tapered dual-mode-single-mode structure optical fiber has low coupling loss with the optical fiber and is perfectly compatible with the optical fiber communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a front view schematic diagram of the all-fiber electro-optic modulator described in the embodiment of the present application;

[0040] Figure 2 A schematic side view of the central area of ​​the all-fiber electro-optic modulator according to an embodiment of the present application;

[0041] Figure 3 This is a schematic diagram of the structure of the single-mode-tapered dual-mode-single-mode structure optical fiber according to an embodiment of the present application;

[0042] Figure 4 The interference valley of the device output spectrum of the all-fiber electro-optic modulator described in the embodiment of the present application at a modulation voltage of 0-100V;

[0043] Figure 5 This is a graph showing the variation of the output light intensity of the all-fiber electro-optic modulator at a wavelength of 1584nm with the voltage in the embodiment of the present application;

[0044] Among them: 1. Single-mode-tapered dual-mode-single-mode structure optical fiber; 2. Organic electro-optic polymer film; ITO conductive glass; 4. Polyimide gasket.

[0045] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0046] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0047] With the popularization and application of new technologies such as cloud computing, the Internet of Things, 5G, and artificial intelligence, people's demand for data continues to increase, and thus the demand for optical transmission networks has also grown rapidly. High-speed modulation of optical signals has become a key link in optical transmission systems. Optical fiber communication technology has gradually become the mainstream communication technology due to its advantages such as low loss, large communication capacity, wide bandwidth, and strong anti-electromagnetic interference. With the large-scale application of optical fiber communication technology, higher requirements are placed on the integration and cost control of electro-optical modulation devices.

[0048] Electro-optic modulator is one of the core components of optical fiber communication system, and its performance greatly affects the performance of optical fiber communication system. Lithium niobate waveguide is an ideal material for electro-optic modulator due to its large electro-optic coefficient (30pm / V) and wide electromagnetic wave transmission window (0.35-5μm). Lithium niobate electro-optic modulator based on Mach-Zehnder (MZ) waveguide structure has become the most widely used modulator in existing systems.

[0049] However, the half-wave voltage of lithium niobate waveguide electro-optical modulator is relatively high (2V), and the manufacturing process is extremely demanding, resulting in high cost. In addition, the coupling between planar waveguide and optical fiber will produce large losses when connected to the optical fiber communication system.

[0050] Organic electro-optic polymers have attracted extensive research due to their ultra-large electro-optic coefficient (1000pm / V), ultra-fast response speed (10fs) and simple preparation process. Various polarization methods are used to make organic polymers anisotropic, thereby obtaining second-order nonlinear effects and electro-optic effects. Under the action of an external electric field, the refractive index of the material will change with the change of the external electric field. In 2002, Bell Laboratories in the United States prepared an organic electro-optic modulator with a bandwidth of up to 200GHz based on DR1 / PMMA materials; in 2017, Kyushu University in Japan used a polymer with an electro-optic coefficient of 165pm / V to make an electro-optic modulator with a half-wave voltage of 0.9V, which can be directly driven by a chip. Existing electro-optic modulators based on organic electro-optic polymers are all planar waveguide structures. When connected to a fiber-optic communication system, the coupling between the optical fiber will produce large losses, and the packaging cost of the waveguide structure will also increase the cost of the device. Therefore, it is of great significance to use organic polymers to prepare an all-fiber electro-optic modulator with high modulation efficiency, high bandwidth, low cost, and easy integration into a fiber-optic communication system.

[0051] As the most basic structural unit for building photonic devices, optical fiber has gradually entered the stage of miniaturization. In addition to realizing the function of optical waveguide, single-mode-tapered dual-mode-single-mode structure optical fiber has many characteristics different from ordinary optical fiber. In order to make the wavelength of the light field in the optical fiber interact with the measured physical quantity, a section of the optical fiber is usually tapered to "expose" the transmitted light in it. The optical fiber after taper of ordinary single-mode optical fiber is called micro-nano-fiber (MNF); single-mode-tapered dual-mode-single-mode structure optical fiber is based on micro-nano fiber, replacing a section of single-mode optical fiber with dual-mode optical fiber, and further tapering the dual-mode optical fiber. The optical fiber generates an evanescent field in the tapered flat area and generates stronger dual-mode interference than micro-nano fiber. The evanescent field interacts with the environment. When the refractive index of the environmental medium changes, the phase difference between the two light modes of dual-mode interference changes, the interference valley moves, and the output light intensity at the corresponding single wavelength changes. By changing the refractive index of the environmental medium, the output light intensity at a single wavelength can be changed, thereby realizing the modulation of light intensity. Therefore, the single-mode-tapered dual-mode-single-mode structure optical fiber is very suitable for designing and manufacturing electro-optic modulators with high modulation efficiency and easy integration into optical fiber communication systems.

[0052] Based on this, in order to solve the problems of low modulation efficiency, complex manufacturing process, high cost and difficulty in integration with optical fiber communication systems of planar waveguide modulators in electro-optic modulators, the present application combines the characteristics of dual-mode interference in the tapered region of a single-mode-tapered dual-mode-single-mode structured optical fiber and the characteristics of the refractive index change of electro-optic polymers with changes in applied voltage, and proposes an all-fiber electro-optic modulator with high modulation efficiency, simple process, low cost and easy integration with optical fiber systems.

[0053] like Figure 1-2As shown, the all-fiber electro-optic modulator described in this application includes:

[0054] Single-mode-tapered dual-mode-single-mode structure optical fiber, wherein the single-mode-tapered dual-mode-single-mode structure optical fiber is a single-mode-dual-mode-single-mode structure optical fiber in which the dual-mode optical fiber region is tapered to form a tapered dual-mode optical fiber;

[0055] ITO conductive glass electrodes, wherein the ITO conductive glass is a top layer ITO conductive glass electrode and a bottom layer ITO conductive glass electrode; the ITO conductive glass electrodes are used to connect an external modulation voltage;

[0056] Polyimide gaskets, the polyimide gaskets are fixed at both ends of the bottom ITO conductive glass;

[0057] An organic electro-optic polymer film is spin-coated on the bottom ITO conductive glass, and the single-mode-tapered dual-mode-single-mode structure optical fiber is placed on the surface of the polarized organic electro-optic polymer film.

[0058] like Figure 3 As shown, as some optional embodiments of the present application, the single-mode-tapered dual-mode-single-mode structure optical fiber is provided in the horizontal direction in sequence: an introduction-single-mode optical fiber, a tapered transition zone 1, a tapered flat zone, a tapered transition zone 2 and an export-single-mode optical fiber;

[0059] Wherein, the import-single-mode optical fiber and the export-single-mode optical fiber are single-mode optical fibers with complete structures;

[0060] The optical fiber diameters of the tapered transition zone 1 and the tapered transition zone 2 gradually change along the axial direction;

[0061] The optical fiber diameter in the tapered flat region remains constant along the axial direction.

[0062] When the light field is input from the lead-in single-mode fiber and transmitted to the tapered transition zone 1, the incident light excites a higher-order mode at the transition zone 1. As the light field propagates, the light interacts with external matter in the form of an evanescent field in the tapered flat region. Finally, dual-mode interference is formed at the tapered transition zone 2, and the accumulated phase difference of the interference is affected by the environmental refractive index and wavelength. The dual-mode interference results corresponding to the transition zone 2 are different, the energy in the fiber core is different, and the transmittance is different. Constructive interference corresponds to the interference peak in the transmission spectrum, while destructive interference corresponds to the interference valley in the transmission spectrum. When the refractive index of the ambient medium changes, the phase difference of the optical mode of the dual-mode interference changes, which is reflected in the movement of the interference valley and the change of the output light intensity at a single wavelength. By changing the refractive index of the ambient medium, the output light intensity at a single wavelength can be changed, thereby achieving modulation of the light intensity.

[0063] As some optional embodiments of the present application, the length of the dual-mode optical fiber in the single-mode-tapered dual-mode-single-mode structure optical fiber is 1 to 100 mm, the diameter of the tapered flat zone is 4 to 40 μm, and the total length of the tapered transition zone 1, the tapered flat zone and the tapered transition zone 2 is 1 to 100 mm. A sufficiently long tapered zone length and a sufficiently thin tapered flat zone diameter enhance the interaction intensity between the light field and the material; the optical fiber is a single-mode-dual-mode tapered-single-mode structure optical fiber, which is a single-mode-dual-mode-single-mode structure optical fiber made by partial melting and taper treatment, and can be directly connected and coupled with an existing optical fiber communication system to reduce coupling loss.

[0064] The thickness of the polyimide gasket is 2-500 μm; the length of the organic electro-optic polymer film is 1-100 mm, the width is 10-10 mm, and the thickness is 0.5-50 μm.

[0065] In order to solve the above technical problems, the present application also proposes a method for preparing the all-fiber electro-optic modulator as described above, comprising the following steps:

[0066] Prepare the single-mode-tapered dual-mode-single-mode structure optical fiber;

[0067] Prepare the organic electro-optic polymer film, spin-coat the organic electro-optic polymer film on the bottom ITO conductive glass, and polarize it to obtain the polarized organic electro-optic polymer film;

[0068] After integrating the single-mode-tapered dual-mode-single-mode structure optical fiber and the polarized organic electro-optic polymer film, a first film optical fiber is obtained;

[0069] The top layer of ITO conductive glass is placed on the top of the electro-optic modulator, and the top layer of ITO conductive glass and the bottom layer of ITO conductive glass are connected to an external modulation voltage to obtain an all-fiber electro-optic modulator.

[0070] As some optional embodiments of the present application, the steps of preparing the single-mode-tapered dual-mode-single-mode structure optical fiber include:

[0071] The two sections of single-mode optical fiber are fused together with a 2cm long dual-mode optical fiber. The single-mode optical fiber end coating layer and the entire dual-mode optical fiber coating layer are removed using optical fiber strippers, and the optical fiber end is cut flat using an optical fiber cutter. Finally, the single-mode optical fiber is fused to both ends of the dual-mode optical fiber using an optical fiber fusion splicer to form a single-mode-dual-mode-single-mode structure optical fiber.

[0072] The two ends of the single-mode-dual-mode-single-mode structure optical fiber are fixed on the fixture of the optical fiber taper system, and the two ends of the optical fiber are connected to the laser and the spectrometer respectively; the flame of the taper system is ignited, and the length and speed of the taper are set at the same time, and the dual-mode optical fiber region of the single-mode-dual-mode-single-mode structure optical fiber is melt-tapered to produce a single-mode-tapered dual-mode-single-mode structure optical fiber with a tapered region length of 25 mm and a tapered flat region diameter of 10 μm.

[0073] As some optional embodiments of the present application, the steps of preparing the organic electro-optic polymer film, spin-coating the organic electro-optic polymer film on the underlying ITO conductive glass, and polarizing the film to obtain the polarized organic electro-optic polymer film include:

[0074] Disperse Red 1 and polymethyl methacrylate are dissolved in anisole solvent and stirred evenly to obtain an organic electro-optic polymer film;

[0075] Spin coating the organic electro-optic polymer film on the bottom ITO conductive glass to obtain a first film;

[0076] polarizing the first film to obtain a polarized organic electro-optic polymer film;

[0077] Wherein, the mass ratio of the disperse red 1 to polymethyl methacrylate is 1:4; the amount of the anisole solvent is 3 mL; and the stirring time is 36 h.

[0078] Organic electro-optic polymer is an electric field sensitive medium. The refractive index of the prepared electro-optic polymer changes with the change of applied voltage. The refractive index change is Δn = -1 / 2n 3 γ 33 E.

[0079] As some optional embodiments of the present application, the step of polarizing the first film to obtain a polarized organic electro-optic polymer film includes:

[0080] The first film is heated and cured and then dried to obtain a second film;

[0081] The second film is heated to the glass transition temperature, a voltage is applied for corona poling for 10-30 minutes, the temperature is lowered to room temperature, the polarization electric field is maintained during the cooling period, and the polarization electric field is removed after the cooling is completed to obtain a polarized organic electro-optic polymer film.

[0082] The heating curing temperature is 60° C., and the heating curing time is 30 min; the drying temperature is 60° C., and the drying time is 12 h.

[0083] As some optional embodiments of the present application, the polarization temperature is 90-120° C., and the polarization voltage is 1-10 kV.

[0084] The ionization of the air around the needle electrode will cause charge to be deposited on the surface of the film sample, resulting in a strong electric field inside the film, which will cause the chromophore molecules to produce a polarization effect. The external voltage is maintained unchanged to reduce the film temperature, and the polarization state of the chromophore molecules is "solidified". As some optional embodiments of the present application, the diameter of the needle electrode of the corona polarization is 1-10 μm, and the distance from the lower electrode is 1-50 mm.

[0085] After the single-mode-tapered dual-mode-single-mode structure optical fiber and the polarized organic electro-optic polymer film are integrated, obtaining the first thin-film optical fiber is achieved by placing the tapered region of the single-mode-tapered dual-mode-single-mode structure optical fiber on the surface of the polarized organic electro-optic polymer film; that is, as some optional embodiments of the present application, the step of obtaining the first thin-film optical fiber after the single-mode-tapered dual-mode-single-mode structure optical fiber and the polarized organic electro-optic polymer film are integrated, comprising:

[0086] Fixing the single-mode-tapered dual-mode-single-mode structure optical fiber on an optical fiber fixture, and moving the translation stage under the optical fiber fixture to make the tapered area of ​​the optical fiber slightly bend downward;

[0087] The polarized organic electro-optic polymer film is fixed on a displacement stage, and the displacement stage is moved until the polarized organic electro-optic polymer film and the single-mode-tapered dual-mode-single-mode structure optical fiber are in contact and integrated to obtain a first film optical fiber.

[0088] The present application is an electro-optic modulator that combines the dual-mode interference characteristics of a single-mode-tapered dual-mode-single-mode structure optical fiber and the refractive index change characteristics of an electro-optic polymer with an applied voltage. When light is transmitted along a single-mode-tapered dual-mode-single-mode structure optical fiber, the light field interacts with the organic electro-optic polymer film in the tapered flat region, and changes in the external electric field cause changes in the refractive index of the organic electro-optic polymer film, thereby causing changes in the dual-mode interference of the light field in the tapered region. The applied voltage can cause the interference wavelength to move and the single-wavelength output light intensity to change, thereby realizing the electro-optic modulation function.

[0089] The technical solution of this application is described in detail below in conjunction with specific embodiments:

[0090] Example 1

[0091] This embodiment provides a single-mode-tapered dual-mode-single-mode all-fiber electro-optic modulator based on an organic electro-optic polymer film and a preparation method thereof. Figure 1 , Figure 2 This is a schematic diagram of the structure of the all-fiber electro-optic modulator described in this application. As shown in the figure, the all-fiber electro-optic modulator includes:

[0092] ITO conductive glass electrodes, wherein the ITO conductive glass is a top layer ITO conductive glass electrode and a bottom layer ITO conductive glass electrode; the ITO conductive glass electrodes are used to connect an external modulation voltage;

[0093] Polyimide gaskets, the polyimide gaskets are fixed at both ends of the bottom ITO conductive glass;

[0094] An organic electro-optic polymer film is spin-coated on the bottom ITO conductive glass, and the single-mode-tapered dual-mode-single-mode structure optical fiber is placed on the surface of the polarized organic electro-optic polymer film.

[0095] like Figure 3 As shown, as some optional embodiments of the present application, the single-mode-tapered dual-mode-single-mode structure optical fiber is provided in the horizontal direction in sequence: an introduction-single-mode optical fiber, a tapered transition zone 1, a tapered flat zone, a tapered transition zone 2 and an export-single-mode optical fiber;

[0096] Wherein, the import-single-mode optical fiber and the export-single-mode optical fiber are single-mode optical fibers with complete structures;

[0097] The optical fiber diameters of the tapered transition zone 1 and the tapered transition zone 2 gradually change along the axial direction;

[0098] The optical fiber diameter in the tapered flat region remains constant along the axial direction.

[0099] The single-mode-tapered dual-mode-single-mode structure optical fiber is prepared by an optical fiber fusion splicer and an optical fiber taper system, and the process is as follows:

[0100] S1. Splice a 2cm long dual-mode optical fiber in the middle of two single-mode optical fibers, use optical fiber strippers to remove the coating layer of the single-mode optical fiber port and all the coating layers of the dual-mode optical fiber, and use an optical fiber cutter to cut the optical fiber port flat, and finally use an optical fiber fusion splicer to fuse the single-mode optical fiber to both ends of the dual-mode optical fiber to make a single-mode-dual-mode-single-mode structure optical fiber.

[0101] S2. Fix both ends of the single-mode-dual-mode-single-mode structure optical fiber on the fixture of the optical fiber taper system, and connect the two ends of the optical fiber to the laser and the spectrometer respectively; ignite the taper system flame, set the taper length and speed at the same time, perform melt taper treatment on the dual-mode optical fiber region of the single-mode-dual-mode-single-mode structure optical fiber, and produce a single-mode-tapered dual-mode-single-mode structure optical fiber with a tapered area length of 25 mm and a tapered flat area diameter of 10 μm.

[0102] The processing of electro-optic polymer films is as follows:

[0103] Disperse Red 1 (DR1) and polymethyl methacrylate (PMMA) with a mass ratio of 1:4 were dissolved in 3mL of anisole solvent and stirred for 36 hours. Polyimide gaskets with a thickness of 50μm were fixed at both ends of the ITO conductive glass, and the organic electro-optic polymer solution was spin-coated onto the ITO conductive glass. The sample was first placed on an electrode plate for heating treatment, heated at 65℃ for 30min to solidify the film; then placed in a vacuum drying oven for drying at 60℃ for 12 hours to evaporate the solvent remaining on the surface of the film, and a DR1 / PMMA polymer film with a length of 1.5cm, a width of 0.3mm, and a thickness of 7μm was obtained; finally, the DR1 / PMMA polymer film was polarized, the film was heated to near the glass transition temperature Tg, and after maintaining the predetermined temperature for 10min, the DC voltage was gradually increased to 3kV, the temperature and polarization electric field were maintained for 10min, and the temperature was gradually reduced to room temperature, the polarization electric field was maintained during the cooling period, and finally the polarization electric field was removed.

[0104] The specific steps of integrating the single-mode-tapered dual-mode-single-mode structure optical fiber with the DR1 / PMMA polymer film are as follows: the two ends of the single-mode-tapered dual-mode-single-mode structure optical fiber are fixed on the optical fiber clamp, and the translation stage under the optical fiber clamp is moved to make the tapered area of ​​the optical fiber slightly bend downward; the ITO conductive glass spin-coated with the DR1 / PMMA polymer film is fixed on the translation stage under the optical fiber, and the translation stage is moved to slowly raise the ITO conductive glass until the DR1 / PMMA polymer film contacts the tapered area of ​​the single-mode-tapered dual-mode-single-mode structure optical fiber; the top layer of ITO conductive glass is placed on the upper end of the optical fiber and the polyimide gasket.

[0105] When light passes through a single-mode-tapered dual-mode-single-mode structured optical fiber, the light field interacts with the organic electro-optic polymer film in the tapered flat region. The applied modulation voltage causes the refractive index of the organic electro-optic polymer film to change, and the change in the refractive index of the organic electro-optic polymer film causes the optical mode of the dual-mode interference of the light field in the tapered region to produce a phase difference change, resulting in the interference valley shift of the device, which manifests as a change in the output light intensity at a single wavelength, thereby realizing the electro-optic modulation function.

[0106] The interference valley of the device output spectrum under different modulation voltages and the output light intensity change at 1584nm wavelength are shown in the figure below: Figure 4 and Figure 5 As shown. Figure 4 and Figure 5 It can be seen that the interference valley of the device output spectrum blue-shifts 26pm under an external modulation voltage of 0-100V, and the output light intensity of the device at a wavelength of 1584nm decreases by 6.5dB under an external modulation voltage of -100-0V.

[0107] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. An all-fiber electro-optic modulator, characterized in that: The all-fiber electro-optic modulator comprises: Single-mode-tapered dual-mode-single-mode structure optical fiber, wherein the single-mode-tapered dual-mode-single-mode structure optical fiber is a single-mode-dual-mode-single-mode structure optical fiber in which the dual-mode optical fiber region is tapered to form a tapered dual-mode optical fiber; The single-mode-tapered dual-mode-single-mode structure optical fiber is provided with: an inlet-single-mode optical fiber, a tapered transition zone 1, a tapered flat zone, a tapered transition zone 2 and an outlet-single-mode optical fiber in the horizontal direction; wherein the inlet-single-mode optical fiber and the outlet-single-mode optical fiber are single-mode optical fibers with complete structures; the optical fiber diameters of the tapered transition zone 1 and the tapered transition zone 2 gradually change along the axial direction; the optical fiber diameter of the tapered flat zone remains unchanged along the axial direction; The length of the dual-mode optical fiber in the single-mode-tapered dual-mode-single-mode structure optical fiber is 1-100 mm, the diameter of the tapered flat zone is 4-40 μm, and the total length of the tapered transition zone 1, the tapered flat zone and the tapered transition zone 2 is 1-100 mm; wherein the thickness of the polyimide gasket is 2-500 μm; the length of the organic electro-optic polymer film is 1-100 mm, the width is 10-10 mm, and the thickness is 0.5-50 μm; ITO conductive glass electrodes, wherein the ITO conductive glass is a top layer ITO conductive glass electrode and a bottom layer ITO conductive glass electrode; the ITO conductive glass electrodes are used to connect an external modulation voltage; Polyimide gaskets, the polyimide gaskets are fixed at both ends of the bottom ITO conductive glass; An organic electro-optic polymer film is spin-coated on the bottom ITO conductive glass, and the single-mode-tapered dual-mode-single-mode structure optical fiber is placed on the surface of the polarized organic electro-optic polymer film.

2. A method for preparing the all-fiber electro-optic modulator as claimed in claim 1, characterized in that: The following steps are involved: Prepare the single-mode-tapered dual-mode-single-mode structure optical fiber; Prepare the organic electro-optic polymer film, spin-coat the organic electro-optic polymer film on the bottom ITO conductive glass, and polarize it to obtain the polarized organic electro-optic polymer film; After integrating the single-mode-tapered dual-mode-single-mode structure optical fiber and the polarized organic electro-optic polymer film, a first film optical fiber is obtained; The top layer of ITO conductive glass is placed on the top of the electro-optic modulator, and the top layer of ITO conductive glass and the bottom layer of ITO conductive glass are connected to an external modulation voltage to obtain an all-fiber electro-optic modulator.

3. The method for preparing the all-fiber electro-optic modulator according to claim 2, characterized in that: The step of preparing the single-mode-tapered dual-mode-single-mode structure optical fiber comprises: A 2 cm long dual-mode optical fiber was fused between two single-mode optical fibers. The coating layer of the single-mode optical fiber port and all the coating layers of the dual-mode optical fiber were removed using optical fiber strippers, and the optical fiber port was cut flat using an optical fiber cutter. Finally, a single-mode optical fiber was fused to both ends of the dual-mode optical fiber using an optical fiber fusion splicer to form a single-mode-dual-mode-single-mode optical fiber. The two ends of the single-mode-dual-mode-single-mode structure optical fiber are fixed on the fixture of the optical fiber taper system, and the two ends of the optical fiber are connected to the laser and the spectrometer respectively; the flame of the taper system is ignited, and the taper length and speed are set at the same time, and the dual-mode optical fiber region of the single-mode-dual-mode-single-mode structure optical fiber is melt-tapered to produce a single-mode-tapered dual-mode-single-mode structure optical fiber with a tapered region length of 25 mm and a tapered flat region diameter of 10 μm.

4. The method for preparing the all-fiber electro-optic modulator according to claim 2, characterized in that: The step of preparing the organic electro-optic polymer film, spin-coating the organic electro-optic polymer film on the bottom ITO conductive glass, and polarizing the film to obtain the polarized organic electro-optic polymer film comprises: Disperse Red 1 and polymethyl methacrylate are dissolved in anisole solvent and stirred evenly to obtain an organic electro-optic polymer film; Spin coating the organic electro-optic polymer film on the bottom ITO conductive glass to obtain a first film; polarizing the first film to obtain a polarized organic electro-optic polymer film; Wherein, the mass ratio of the disperse red 1 to polymethyl methacrylate is 1:4; the amount of the anisole solvent is 3 mL; and the stirring time is 36 h.

5. The method for preparing the all-fiber electro-optic modulator according to claim 4, characterized in that: The step of polarizing the first film to obtain a polarized organic electro-optic polymer film comprises: The first film is heated and cured and then dried to obtain a second film; The second film is heated to the glass transition temperature, a voltage is applied for corona poling for 10-30 minutes, the temperature is lowered to room temperature, the polarization electric field is maintained during the cooling period, and the polarization electric field is removed after the cooling is completed to obtain a polarized organic electro-optic polymer film.

6. The method for preparing the all-fiber electro-optic modulator according to claim 5, characterized in that: The polarization temperature is 90-120° C., and the polarization voltage is 1-10 kV.

7. The method for preparing the all-fiber electro-optic modulator according to claim 5, characterized in that: The needle tip of the corona polarization needle electrode has a diameter of 1-10 μm and a distance from the lower electrode of 1-50 mm.

8. The method for preparing the all-fiber electro-optic modulator according to claim 2, characterized in that: The step of integrating the single-mode-tapered dual-mode-single-mode structure optical fiber and the polarized organic electro-optic polymer film to obtain a first film optical fiber comprises: Fixing the single-mode-tapered dual-mode-single-mode structure optical fiber on an optical fiber fixture, and moving the translation stage under the optical fiber fixture to make the tapered area of ​​the optical fiber slightly bend downward; The polarized organic electro-optic polymer film is fixed on a displacement stage, and the displacement stage is moved until the polarized organic electro-optic polymer film and the single-mode-tapered dual-mode-single-mode structure optical fiber are in contact and integrated to obtain a first film optical fiber.

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