An all-optical modulator based on NCB material micro-nano optical fiber composite device

Abstract

The present application provides an all-optical modulator based on a micro-nano optical fiber composite device of NCB material, comprising: a signal laser source (21), a first polarization controller (22), a pump laser source (23), a thulium-doped optical fiber amplifier (24), a second polarization controller (25), a coupler (26), an all-optical modulator (27), a polarization-dependent isolator (28) and a spectrum analyzer (29); signal light output by the signal laser source (21) enters the coupler (26) through the first polarization controller (22); pump light output by the pump laser source (23) is power-amplified by the thulium-doped optical fiber amplifier (24) and enters the coupler (26) through the second polarization controller (25); the pump light and the signal light are injected into the all-optical modulator (27) together by the coupler (26), so that the projection rate of the polarization-dependent isolator (28) to the signal light changes, and the spectrum analyzer (29) finally captures the intensity change of the signal light.

Description

Technical Field

[0001] The invention relates to the field of optical fiber communication, and in particular to an all-optical modulator based on an NCB material micro-nano optical fiber composite device. Background Art

[0002] As the demand for information processing speed in the field of optical communications continues to grow, there is an urgent need to develop the next generation of optical communication systems. In optical communication systems, optical modulators are one of the key components for realizing optical signal processing, which can be used to adjust parameters such as the intensity, phase, and polarization of optical signals. When non-all-optical optical modulators are connected to optical communication networks or work in conjunction with optical communication networks, there will be large insertion losses, which seriously affects their energy efficiency and work efficiency. All-optical modulators that use "light-to-light" signal conversion have a natural compatibility advantage with current optical communication systems, and can greatly reduce the connection loss of devices in the system, thereby better promoting the development and application of next-generation optical communication systems.

[0003] As devices gradually develop towards integration and miniaturization, the research on micro-nano optical devices has received extensive attention from researchers. Micro-nano optical fibers have become one of the ideal platforms for exploring new optical devices due to their low loss, simple fabrication, strong light field manipulation capabilities, and significant evanescent fields. In particular, the emergence of new nanomaterials represented by graphene has brought another leap forward for micro-nano optical fibers as optical carriers. These new nanomaterials have received extensive attention in the field of optical modulation. Their applications in the field of optical modulation have unique advantages, such as wide coverage of wavelengths, fast modulation speed, and easy integration. They are worthy of further exploration and research, and also provide new design ideas for the development of all-optical devices. By combining different nanomaterials with micro-nano optical fibers, all-optical signal processing devices with multiple functions can be produced. In the past few years, researchers have used graphene, black phosphorus, and molybdenum disulfide to achieve efficient wavelength conversion and all-optical modulation. However, while these materials exhibit remarkable optoelectronic properties, they are also accompanied by some problems that cannot be ignored, such as: graphene has a low damage threshold and relatively weak absorption; black phosphorus has a strong third-order nonlinear coefficient, but is very easy to oxidize and fail; the carrier mobility of molybdenum disulfide is easily affected by charged particles. Therefore, it is still necessary to continue to find other suitable new nanomaterials. Summary of the invention

[0004] At present, all-optical modulators based on nanomaterials and micro-nano optical fibers are mainly concentrated in the 1550nm band, and there are few reports on other bands. Moreover, with the continuous upgrading of optical communication needs and the gradual scarcity of spectrum resources, optical communication systems applied to the mid-infrared band have become one of the key technologies. At present, the preparation and characteristic research of micro-nano optical fiber all-optical modulators in the mid-infrared 2μm band are still in the development stage, which greatly restricts the development and application of mid-infrared band optical communication technology. Therefore, it is very necessary to explore the all-optical modulation devices in the mid-infrared 2μm band in depth, which has important scientific significance for the academic research and industrial application of mid-infrared 2μm band optical communication. The mid-infrared 2μm band has attracted widespread attention as a spectral range with great potential. It is in the safe band of the human eye and the atmospheric transmission window, and has unique application prospects in the fields of free space optical communication and atmospheric sensing.

[0005] The present application provides a method for preparing a nitrogen-doped mesoporous carbon ball. The invention discloses an all-optical modulator of a micro-nano optical fiber composite device based on NCB material, characterized in that the all-optical modulator of the micro-nano optical fiber composite device based on NCB material comprises: a signal laser source 21, a first polarization controller 22, a pump laser source 23, a thulium-doped fiber amplifier 24, a second polarization controller 25, a coupler 26, an all-optical modulator 27 based on a nitrogen-doped mesoporous carbon ball nanomaterial NCB deposition micro-nano optical fiber composite device, a polarization-dependent isolator 28 and a spectrum analyzer 29; the signal light output by the signal laser source 21 enters the coupler 26 through the first polarization controller 22, the pump light output by the pump laser source 23 is power-amplified by the thulium-doped fiber amplifier 24, enters the coupler 26 through the second polarization controller 25, the pump light and the signal light are injected into the all-optical modulator 27 together by the coupler 26, and due to the influence of nonlinear effect, the pump light changes the polarization state of the signal light, so that the signal light undergoes polarization rotation, so that the projection rate of the polarization-dependent isolator 28 to the signal light changes, and the spectrum analyzer 29 finally captures the intensity change of the signal light.

[0006] In combination with the first aspect, in a possible implementation, the signal laser source 21 is a wavelength tunable fiber laser in the mid-infrared 2 micron band, and its central wavelength is tuned in the range of 1900-2000nm; the pump laser source 23 is a fixed wavelength fiber laser in the mid-infrared 2μm band, and its central wavelength is 1954nm; when the pump laser source 23 is turned off, the first polarization controller 22 controls the polarization state of the signal light to be perpendicular to the polarization-dependent isolator 28, thereby suppressing the transmission of the signal light; initially, the output laser wavelength of the signal laser source 21 is 1956nm, and the output laser wavelength of the pump laser source 23 is 1954nm; the maximum output power of the thulium-doped fiber amplifier 24 is 300mW.

[0007] In combination with the first aspect, in a possible implementation, the all-optical modulator 27 is connected to the output end of the coupler 26, and the pump light with a wavelength of 1954nm and the signal light with a wavelength of 1956nm enter the all-optical modulator 27 together. When the power of the pump laser source 23 gradually increases, the nonlinear interaction between the signal light and the pump light continues to intensify, resulting in additional nonlinear phase shift. Due to the nonlinear refractive index of the NCB and the strong interaction between light and matter, the signal light causes a polarization change after propagating through the all-optical modulator 27, so that the transmittance of the polarization-dependent isolator 28 to the signal light increases, and the intensity of the signal light in the spectrum analyzer 29 increases.

[0008] In combination with the first aspect, in a possible implementation, the all-optical modulator 27 based on the nitrogen-doped mesoporous carbon ball nanomaterial NCB deposited micro-nano optical fiber composite device is prepared by an optical deposition method, and the preparation device includes: a 980nm band laser 11, a micro-nano optical fiber 12, an optical power meter 13, and a microscope 14; wherein, the output of the 980nm band laser 11 is connected to the input end of the micro-nano optical fiber 12, and the output end of the micro-nano optical fiber 12 is connected to the optical power meter 13; when the output laser of the 980nm band laser 11 is input into the beam waist region of the micro-nano optical fiber 12 through the input end of the micro-nano optical fiber 12, the NCB isopropanol solution is deposited on the beam waist region of the micro-nano optical fiber 12, and the deposition state of the material is observed through the microscope 14, and the optical power meter 13 is used to monitor the dynamic change of the output power, and the transmission loss of the composite structure of the NCB material and the micro-nano optical fiber 12 is measured; the micro-nano optical fiber 12 used is formed by tapering a standard single-mode optical fiber, and the beam waist region diameter of the micro-nano optical fiber 12 is ~6μm. When the power displayed by the optical power meter 13 is stable, material deposition is no longer performed; at this time, the NCB-deposited micro-nano optical fiber composite device has been prepared.

[0009] In combination with the first aspect, in a possible implementation, the preparation process of the NCB isopropanol solution includes: step 1: dissolving 5g of a copolymer of polyethylene oxide-polypropylene oxide-polyethylene oxide in 100ml of deionized water to form a spherical micelle solution; step 2: adding 2g of o-aminophenol, 1g of aniline and 2g of ammonia water to the spherical micelle solution, and magnetically stirring for 60 minutes, then heating the mixed solution to 90°C, and then continuously stirring for 24 hours; step 3: collecting the solid product by a centrifuge, washing it with water and ethanol, and drying it at 70°C for 12 hours to obtain an NCB nanomaterial; step 4: taking an appropriate amount of the NCB nanomaterial, adding it to isopropanol, and then ultrasonicating and centrifuging it in turn, taking out the centrifuged dispersion, and preparing an NCB isopropanol dispersion.

[0010] The second aspect of the present application provides an all-optical modulator of a micro-nano optical fiber composite device based on NCB material, characterized in that the all-optical modulator of the micro-nano optical fiber composite device based on NCB material comprises: a signal laser source 21, a first polarization controller 22, a pump laser source 23, a second polarization controller 25, a coupler 26, a thulium-doped fiber amplifier 24, a highly nonlinear optical fiber 30, an all-optical modulator 27 based on nitrogen-doped mesoporous carbon ball nanomaterial NCB deposition micro-nano optical fiber composite device, and a spectrum analyzer 29; the signal laser source 21 and the pump laser source 23 output signal light and pump light respectively, and enter the coupler 26 through the first polarization controller 22 and the second polarization controller 25 respectively to couple the two beams of light into one beam, and at the same time, the thulium-doped fiber amplifier 24 performs power enhancement, and enters the all-optical modulator 27 based on the NCB deposition micro-nano optical fiber composite device after passing through a section of highly nonlinear optical fiber 30, generating secondary cascade four-wave mixing, and finally the test spectrum is observed by the spectrum analyzer 29.

[0011] In combination with the second aspect, in a possible implementation, the first polarization controller 22 and the second polarization controller 25 are used to control the polarization state of the signal light to remain parallel to the polarization state of the pump light, and the signal light wavelength and the pump light wavelength output by the signal laser source 21 and the pump laser source 23 are 1954nm and 1956nm respectively; the length of the high nonlinear optical fiber 30 is 100m.

[0012] In combination with the second aspect, in a possible implementation, the all-optical modulator 27 based on the nitrogen-doped mesoporous carbon ball nanomaterial NCB deposited micro-nano optical fiber composite device is prepared by an optical deposition method, and the preparation device includes: a 980nm band laser 11, a micro-nano optical fiber 12, an optical power meter 13, and a microscope 14; wherein, the output of the 980nm band laser 11 is connected to the input end of the micro-nano optical fiber 12, and the output end of the micro-nano optical fiber 12 is connected to the optical power meter 13; when the output laser of the 980nm band laser 11 is input into the beam waist region of the micro-nano optical fiber 12 through the input end of the micro-nano optical fiber 12, the NCB isopropanol solution is deposited on the beam waist region of the micro-nano optical fiber 12, and the deposition state of the material is observed through the microscope 14, and the optical power meter 13 is used to monitor the dynamic change of the output power, and the transmission loss of the composite structure of the NCB material and the micro-nano optical fiber 12 is measured; the micro-nano optical fiber 12 used is formed by tapering a standard single-mode optical fiber, and the beam waist region diameter of the micro-nano optical fiber 12 is ~6μm. When the power displayed by the optical power meter 13 is stable, material deposition is no longer performed; at this time, the NCB-deposited micro-nano optical fiber composite device has been prepared.

[0013] In combination with the second aspect, in a possible implementation, the preparation process of the NCB isopropanol solution includes: step 1: dissolving 5g of a copolymer of polyethylene oxide-polypropylene oxide-polyethylene oxide in 100ml of deionized water to form a spherical micelle solution; step 2: adding 2g of o-aminophenol, 1g of aniline and 2g of ammonia water to the spherical micelle solution, and performing magnetic stirring for 60 minutes, then heating the mixed solution to 90°C, and then continuously stirring for 24 hours; step 3: collecting the solid product by a centrifuge, washing it with water and ethanol, and drying it at 70°C for 12 hours to obtain an NCB nanomaterial; step 4: taking an appropriate amount of the NCB nanomaterial, adding it to isopropanol, and then performing ultrasonication and centrifugation on it in turn, and then taking out the centrifuged dispersion to prepare an NCB isopropanol dispersion.

[0014] All-optical switching and all-optical wavelength conversion technology are one of the key technologies for realizing all-optical communication. At present, all-optical devices based on these two technologies are mainly concentrated in the 1550nm band. However, the laser coherence in this band is easily disturbed by atmospheric turbulence, and the impact on communication quality is more serious in rainy and snowy weather, especially in haze weather, and even communication may be interrupted. The mid-infrared 2μm band is in the atmosphere and smoke transmission window. Since the scattering intensity decreases with the wavelength of light, the mid-infrared 2μm band is less affected by atmospheric scattering than the 1.55μm band currently used in space laser communication. Moreover, the mid-infrared 2μm band is a human eye-safe band and has a larger safety flux compared to 1.55μm. Therefore, it is of great significance to study the all-optical switching and wavelength conversion of mid-infrared 2μm band lasers in all-optical communication. The present invention realizes all-optical switching and all-optical wavelength conversion simultaneously for the first time in the mid-infrared 2μm band, providing a new and effective way for all-optical signal processing in the mid-infrared 2μm band, and also promoting the development and application of new nanomaterials in optical communications. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of a preparation device for preparing an all-optical modulator based on NCB deposition micro-nano optical fiber composite device using an optical deposition method provided in an embodiment of the present application;

[0016] Figure 2 A schematic diagram of an all-optical modulator of a micro-nano optical fiber composite device based on NCB material provided in an embodiment of the present application;

[0017] Figure 3a The test results of a micro-nano optical fiber without NCB deposition in the first embodiment provided in the embodiments of the present application;

[0018] Figure 3b The test results of a micro-nano optical fiber depositing NCB in the first embodiment provided in the embodiments of the present application;

[0019] Figure 4 A schematic diagram of an all-optical modulator of a micro-nano optical fiber composite device based on NCB material provided in an embodiment of the present application;

[0020] Figure 5a The test result of a micro-nano optical fiber without NCB deposition in the second embodiment provided in the embodiment of the present application;

[0021] Figure 5b This is the test result of a micro-nano optical fiber with NCB deposited in the second embodiment provided in the embodiments of the present application. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.

[0023] The term "and / or" in this application can be a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the associated objects before and after are in an "or" relationship.

[0024] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or modules is not necessarily limited to those steps or modules that are clearly listed, but may include other steps or modules that are not clearly listed or inherent to these processes, methods, products or devices.

[0025] As devices gradually develop towards integration and miniaturization, the research on micro-nano optical devices has received extensive attention from researchers. Micro-nano optical fibers have become one of the ideal platforms for exploring new optical devices due to their low loss, simple fabrication, strong light field manipulation capabilities, and significant evanescent fields. In particular, the emergence of new nanomaterials represented by graphene has brought another leap forward for micro-nano optical fibers as optical carriers. These new nanomaterials have received extensive attention in the field of optical modulation. Their applications in the field of optical modulation have unique advantages, such as wide coverage of wavelengths, fast modulation speed, and easy integration. They are worthy of further exploration and research, and also provide new design ideas for the development of all-optical devices. By combining different nanomaterials with micro-nano optical fibers, all-optical signal processing devices with multiple functions can be produced. In the past few years, researchers have used graphene, black phosphorus, and molybdenum disulfide to achieve efficient wavelength conversion and all-optical modulation. However, while these materials exhibit remarkable optoelectronic properties, they are also accompanied by some problems that cannot be ignored, such as: graphene has a low damage threshold and relatively weak absorption; black phosphorus has a strong third-order nonlinear coefficient, but is very easy to oxidize and fail; the carrier mobility of molybdenum disulfide is easily affected by charged particles. Therefore, it is still necessary to continue to find other suitable new nanomaterials.

[0026] At present, all-optical modulators based on nanomaterials and micro-nano optical fibers are mainly concentrated in the 1550nm band, and there are few reports on other bands. Moreover, with the continuous upgrading of optical communication needs and the gradual scarcity of spectrum resources, optical communication systems applied to the mid-infrared band have become one of the key technologies. At present, the preparation and characteristic research of micro-nano optical fiber all-optical modulators in the mid-infrared 2μm band are still in the development stage, which greatly restricts the development and application of mid-infrared band optical communication technology. Therefore, it is very necessary to explore the all-optical modulation devices in the mid-infrared 2μm band in depth, which has important scientific significance for the academic research and industrial application of mid-infrared 2μm band optical communication. The mid-infrared 2μm band has attracted widespread attention as a spectral range with great potential. It is in the safe band of the human eye and the atmospheric transmission window, and has unique application prospects in the fields of free space optical communication and atmospheric sensing.

[0027] Therefore, the present application firstly adopts aqueous self-assembly method to prepare nitrogen-doped mesoporous carbon ball (NCB) nitrogen-doped mesoporous carbon ball nanomaterials, as follows: 5g of polyethylene oxide-polypropylene oxide-polyethylene oxide copolymer is dissolved in 100 ml of deionized water to form a spherical micelle solution. After that, 2g of o-aminophenol, 1g of aniline and 2g of a certain concentration of ammonia water are added to the above solution, and magnetic stirring is performed for 60 minutes, and then the mixed solution is heated to 90°C and stirred continuously for 24 hours. After that, the solid product is collected by centrifuge, washed with water and ethanol, and then dried at 70°C for 12 hours to obtain NCB nanomaterials. Finally. Take an appropriate amount of the above NCB nanomaterial, add it to isopropanol, and then ultrasonicate and centrifuge it in turn, and then take out the centrifuged dispersion to prepare NCB isopropanol dispersion.

[0028] Secondly, the composite structure device of the new material NCB deposition micro-nano optical fiber was prepared by optical deposition method. The experimental device is shown in the attached Figure 1 As shown, the device mainly includes: a 980nm band laser 11, a micro-nano optical fiber 12, an optical power meter 13, and a microscope 14; wherein, the output of the 980nm band laser 11 is connected to the input end of the micro-nano optical fiber 12, and the output end of the micro-nano optical fiber 12 is connected to the optical power meter 13; when the output laser of the 980nm band laser 11 is input into the beam waist area of ​​the micro-nano optical fiber 12 through the input end of the micro-nano optical fiber 12, the NCB isopropyl alcohol solution is deposited on the beam waist area of ​​the micro-nano optical fiber 12, and the deposition state of the material is observed through the microscope 14, and the optical power meter 13 is used to monitor the dynamic change of the output power, and the transmission loss of the composite structure of the NCB material and the micro-nano optical fiber 12 is measured; the micro-nano optical fiber 12 used is formed by tapering a standard single-mode optical fiber, and the beam waist area diameter of the micro-nano optical fiber 12 is ~6μm. When the power displayed by the optical power meter 13 is stable, no more material deposition is performed; at this time, the micro-nano optical fiber composite device with NCB deposition has been prepared.

[0029] The first embodiment provided by this application is as follows: an all-optical modulator based on a micro-nano optical fiber composite device is constructed to realize an optical Kerr switch. The experimental device is as shown in the attached Figure 2 As shown, the device mainly includes a signal laser source 21, a first polarization controller 22, a pump laser source 23, a thulium-doped fiber amplifier 24, a second polarization controller 25, a coupler 26, an all-optical modulator 27 based on NCB deposited micro-nano optical fiber composite devices, a polarization-dependent isolator 28 and a spectrum analyzer 29.

[0030] The signal light output by the signal laser source 21 enters the coupler 26 through the first polarization controller 22, the pump light output by the pump laser source 23 is power-amplified by the thulium-doped fiber amplifier 24, and enters the coupler 26 through the second polarization controller 25. The pump light and the signal light are injected into the all-optical modulator 27 together by the coupler 26. Due to the influence of the nonlinear effect, the pump light will change the polarization state of the signal light, causing the polarization rotation of the signal light, and causing the projection rate of the polarization-dependent isolator 28 to the signal light to change. The intensity change of the signal light is finally captured by the spectrum analyzer 29, thereby achieving the effect of the optical switch.

[0031] Among them, the signal laser source 21 is a wavelength tunable fiber laser in the mid-infrared 2μm band, and its central wavelength can be tuned in the range of 1900-2000nm; the pump laser source 23 is a fixed wavelength fiber laser in the mid-infrared 2μm band, and its central wavelength is 1954nm; when the pump laser source 23 is turned off, the first polarization controller 22 controls the polarization state of the signal light to be perpendicular to the polarization-dependent isolator 28 to minimize the transmission of the signal light; initially, the output laser wavelength of the signal laser source 21 is 1956nm, and the output laser wavelength of the pump laser source 23 is 1954nm; the maximum output power of the thulium-doped fiber amplifier 24 is 300mW.

[0032] In addition, the working principle of the optical Kerr switch here is: the all-optical modulator 27 is connected to the output end of the coupler 26, and the pump light with a wavelength of 1954nm and the signal light with a wavelength of 1956nm enter the all-optical modulator 27 together. When the power of the pump laser source 23 gradually increases, the nonlinear interaction between the signal light and the pump light continues to intensify, resulting in additional nonlinear phase shift. Due to the nonlinear refractive index of the NCB and the strong interaction between light and matter, the signal light causes a polarization change after propagating through the all-optical modulator 27, so that the transmittance of the polarization-dependent isolator 28 to the signal light increases, which is reflected in the spectrum analyzer 29 as an increase in the intensity of the signal light. Therefore, adjusting the intensity of the pump light can allow the signal light to have different "on" or "off" states, thereby realizing the intensity modulation of the signal light. The experimental measurement results are shown in the attached figure. Figure 3a and Figure 3b shown. Figure 3a This is the test result of the micro-nano optical fiber without NCB deposition. Figure 3b This is the test result of the NCB-deposited micro-nano optical fiber. Obviously, the NCB-deposited micro-nano optical fiber composite device exhibits a significant optical switching effect.

[0033] The second embodiment provided by the present application is as follows: an all-optical modulator based on a micro-nano optical fiber composite device is constructed to realize optical wavelength conversion. The experimental device is as shown in the attached Figure 4As shown, the device mainly includes a signal laser source 21, a first polarization controller 22, a pump laser source 23, a second polarization controller 25, a coupler 26, a thulium-doped fiber amplifier 24, a highly nonlinear optical fiber 30, the all-optical modulator 27, and a spectrum analyzer 29.

[0034] The signal laser source 21 and the pump laser source 23 output signal light and pump light respectively, which respectively pass through the first polarization controller 22 and the second polarization controller 25 and enter the coupler 26 to couple the two beams of light into one beam. At the same time, the power is enhanced by the thulium-doped fiber amplifier 24, and then enters the all-optical modulator 27 after passing through a section of highly nonlinear optical fiber 30 to generate secondary cascade four-wave mixing. Finally, the test spectrum is observed by the spectrum analyzer 29 to achieve conversion of different wavelengths.

[0035] Since the four-wave mixing phenomenon is extremely sensitive to the polarization state, it is necessary to strictly control the first polarization controller 22 and the second polarization controller 25 to ensure that the polarization state of the signal light is parallel to the polarization state of the pump light, so as to obtain the best conversion efficiency. Figure 2 The signal light wavelength and pump light wavelength output by the signal laser source 21 and the pump laser source 23 are 1954nm and 1956nm respectively.

[0036] It should be noted that when the light passes through the highly nonlinear optical fiber 30 and the all-optical modulator 27 of the NCB material deposited micro-nano optical fiber composite device in sequence, a secondary four-wave mixing phenomenon will occur, that is, the idler light generated by the primary four-wave mixing phenomenon will once again interact nonlinearly with the original signal light to generate a new idler light with a wavelength different from the primary one. The experimental results are shown in Figure 2. Figure 5a and Figure 5b shown. Figure 5a This is the test result of the micro-nano optical fiber without NCB deposition. Figure 5bThis is the test result of the micro-nano optical fiber deposited with NCB. Obviously, the NCB deposited micro-nano optical fiber composite device shows an obvious wavelength conversion effect. In addition, the working principle of wavelength conversion here is as follows: optical wavelength conversion depends on the generation of four-wave mixing phenomenon, which mainly depends on the third-order nonlinear polarizability of the medium. In the process of four-wave mixing, energy conservation and momentum conservation need to be satisfied at the same time, that is, the light participating in the interaction can achieve efficient energy conversion only when it meets the phase matching condition. Here, according to the degenerate four-wave mixing process, only two beams of light are used, that is, the four-wave mixing phenomenon is completed by the signal light and the pump light, and two new idler lights are generated. On this basis, high nonlinear optical fiber and micro-nano optical fiber coated with carbon material are used to further enhance the four-wave mixing, and a secondary four-wave mixing phenomenon is generated. The original idler light, signal light and pump light complete the degenerate four-wave mixing process again to generate new idler light of different wavelengths. Since the generated idler light can inherit the information of the original signal light, it can achieve the function of completing different wavelength conversion of optical signals in the optical domain.

[0037] All-optical switching and all-optical wavelength conversion technology are one of the key technologies for realizing all-optical communication. At present, all-optical devices based on these two technologies are mainly concentrated in the 1550nm band. However, the laser coherence in this band is easily disturbed by atmospheric turbulence, and the impact on communication quality is more serious in rainy and snowy weather, especially in haze weather, and even communication may be interrupted. The mid-infrared 2μm band is in the atmosphere and smoke transmission window. Since the scattering intensity decreases with the wavelength of light, the mid-infrared 2μm band is less affected by atmospheric scattering than the 1.55μm band currently used in space laser communication. Moreover, the mid-infrared 2μm band is a human eye-safe band and has a larger safety flux compared to 1.55μm. Therefore, it is of great significance to study the all-optical switching and wavelength conversion of mid-infrared 2μm band lasers in all-optical communication. The present invention realizes all-optical switching and all-optical wavelength conversion simultaneously for the first time in the mid-infrared 2μm band, providing a new and effective way for all-optical signal processing in the mid-infrared 2μm band, and also promoting the development and application of new nanomaterials in optical communications.

[0038] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0039] In the embodiments provided in this application, it should be understood that the disclosed methods can be implemented in other ways without exceeding the spirit and scope of this application. The current embodiment is only an illustrative example and should not be used as a limitation. The specific content given should not limit the purpose of this application. For example, some features can be ignored or not executed.

[0040] The technical means disclosed in the present application are not limited to the technical means disclosed in the above-mentioned implementation methods, but also include technical solutions composed of any combination of the above technical features. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of this application, and these improvements and modifications are also regarded as the protection scope of this application.

[0041] The above is a detailed introduction to an all-optical modulator based on a micro-nano optical fiber composite device of NCB material provided in the embodiment of the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and its core idea of ​​the present application; at the same time, for ordinary technicians in this field, according to the idea of ​​the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An all-optical modulator based on a micro-nano optical fiber composite device of NCB material, characterized in that: The all-optical modulator of the micro-nano optical fiber composite device based on NCB material includes: A signal laser source (21), a first polarization controller (22), a pump laser source (23), a thulium-doped fiber amplifier (24), a second polarization controller (25), a coupler (26), an all-optical modulator (27) based on a nitrogen-doped mesoporous carbon sphere nanomaterial NCB deposition micro-nano optical fiber composite device, a polarization-dependent isolator (28), and a spectrum analyzer (29); The signal light output by the signal laser source (21) passes through the first polarization controller (22) and enters the coupler (26); the pump light output by the pump laser source (23) is power-amplified by the thulium-doped fiber amplifier (24) and enters the coupler (26) through the second polarization controller (25); the pump light and the signal light are injected into the all-optical modulator (27) together through the coupler (26); due to the influence of the nonlinear effect, the pump light changes the polarization state of the signal light, causing the signal light to undergo polarization rotation, so that the projection rate of the polarization-dependent isolator (28) to the signal light changes, and the intensity change of the signal light is finally captured by the spectrum analyzer (29); The NCB material is an NCB isopropanol solution, wherein the preparation process of the NCB isopropanol solution comprises: Step 1: dissolve 5 g of polyethylene oxide-polypropylene oxide-polyethylene oxide copolymer in 100 ml of deionized water to form a spherical micelle solution; Step 2: adding 2 g of o-aminophenol, 1 g of aniline and 2 g of ammonia water to the spherical micelle solution, and performing magnetic stirring for 60 minutes, then heating the mixed solution to 90° C., and then continuing stirring for 24 hours; Step 3: Collect the solid product by centrifuge, wash with water and ethanol, and dry at 70° C. for 12 hours to obtain NCB nanomaterials; Step 4: Take an appropriate amount of the NCB nanomaterial, add it to isopropanol, and then perform ultrasound and centrifugation on it in sequence, take out the centrifuged dispersion, and prepare an NCB isopropanol dispersion.

2. The all-optical modulator of the micro-nano optical fiber composite device based on NCB material according to claim 1, characterized in that: The signal laser source (21) is a wavelength tunable fiber laser in the mid-infrared 2 micron band, and its central wavelength is tuned within the range of 1900-2000 nm; The pump laser source (23) is a fixed wavelength fiber laser in the mid-infrared 2 μm band, and its central wavelength is 1954 nm; When the pump laser source (23) is turned off, the first polarization controller (22) controls the polarization state of the signal light to be perpendicular to the polarization-dependent isolator (28), thereby suppressing the transmission of the signal light; Initially, the output laser wavelength of the signal laser source (21) is 1956 nm, and the output laser wavelength of the pump laser source (23) is 1954 nm; The maximum output power of the thulium-doped fiber amplifier (24) is 300 mW.

3. The all-optical modulator of the micro-nano optical fiber composite device based on NCB material according to claim 2, characterized in that: The all-optical modulator (27) is connected to the output end of the coupler (26), and pump light with a wavelength of 1954 nm and signal light with a wavelength of 1956 nm enter the all-optical modulator (27) together. When the power of the pump laser source (23) is gradually increased, the nonlinear interaction between the signal light and the pump light is continuously aggravated, resulting in an additional nonlinear phase shift. Due to the nonlinear refractive index of the NCB and the strong interaction between light and matter, the signal light causes a polarization change after propagating through the all-optical modulator (27), thereby increasing the transmittance of the polarization-dependent isolator (28) to the signal light, and increasing the intensity of the signal light in the spectrum analyzer (29).

4. The all-optical modulator of the micro-nano optical fiber composite device based on NCB material according to claim 1, characterized in that: The all-optical modulator (27) based on the nitrogen-doped mesoporous carbon ball nanomaterial NCB deposition micro-nano optical fiber composite device is prepared by an optical deposition method, and the preparation device includes: A 980 nm laser (11), a micro-nano optical fiber (12), an optical power meter (13), and a microscope (14); wherein the output of the 980 nm laser (11) is connected to the input end of the micro-nano optical fiber (12), and the output end of the micro-nano optical fiber (12) is connected to the optical power meter (13); When the output laser of the 980nm band laser (11) is input into the beam waist region of the micro-nano optical fiber (12) through the input end of the micro-nano optical fiber (12), the NCB isopropyl alcohol solution is deposited on the beam waist region of the micro-nano optical fiber (12), and the deposition state of the material is observed through a microscope (14), while the dynamic change of the output power is monitored using an optical power meter (13), and the transmission loss of the composite structure of the NCB material and the micro-nano optical fiber (12) is measured; The micro-nano optical fiber (12) used is formed by taper-drawing a standard single-mode optical fiber, and the diameter of the beam waist region of the micro-nano optical fiber (12) is ~6μm; when the power displayed by the optical power meter (13) is stable, material deposition is no longer performed; at this time, the NCB-deposited micro-nano optical fiber composite device has been prepared.

5. An all-optical modulator based on a micro-nano optical fiber composite device of NCB material, characterized in that: The all-optical modulator of the micro-nano optical fiber composite device based on NCB material includes: A signal laser source (21), a first polarization controller (22), a pump laser source (23), a second polarization controller (25), a coupler (26), a thulium-doped fiber amplifier (24), a highly nonlinear optical fiber (30), an all-optical modulator (27) based on a nitrogen-doped mesoporous carbon sphere nanomaterial NCB deposition micro-nano optical fiber composite device, and a spectrum analyzer (29); The signal laser source (21) and the pump laser source (23) output signal light and pump light respectively, which respectively pass through the first polarization controller (22) and the second polarization controller (25) and enter the coupler (26) to couple the two beams of light into one beam, and are simultaneously power-enhanced by the thulium-doped fiber amplifier (24). After passing through a section of highly nonlinear optical fiber (30), the signal light enters the all-optical modulator (27) based on the NCB-deposited micro-nano optical fiber composite device to generate secondary cascade four-wave mixing, and finally a test spectrum is observed by the spectrum analyzer (29); The NCB material is an NCB isopropanol solution, wherein the preparation process of the NCB isopropanol solution comprises: Step 1: dissolve 5 g of polyethylene oxide-polypropylene oxide-polyethylene oxide copolymer in 100 ml of deionized water to form a spherical micelle solution; Step 2: adding 2 g of o-aminophenol, 1 g of aniline and 2 g of ammonia water to the spherical micelle solution, and performing magnetic stirring for 60 minutes, then heating the mixed solution to 90° C., and then continuing stirring for 24 hours; Step 3: Collect the solid product by centrifuge, wash with water and ethanol, and dry at 70° C. for 12 hours to obtain NCB nanomaterials; Step 4: Take an appropriate amount of the NCB nanomaterial, add it to isopropanol, and then perform ultrasound and centrifugation on it in sequence, and then take out the centrifuged dispersion to prepare an NCB isopropanol dispersion.

6. The all-optical modulator of the micro-nano optical fiber composite device based on NCB material according to claim 5, characterized in that: The first polarization controller (22) and the second polarization controller (25) are used to control the polarization state of the signal light to remain parallel to the polarization state of the pump light. The wavelength of the signal light and the wavelength of the pump light output by the signal laser source (21) and the pump laser source (23) are 1954 nm and 1956 nm respectively. The length of the high nonlinear optical fiber (30) is 100 m.

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