Gain fiber and light amplification device

Abstract

The embodiment of the invention discloses a gain optical fiber and a light amplification device. The light amplification performance with high gain and low noise coefficient can be obtained. The gain fiber comprises a protective layer, an outer cladding, an inner cladding, at least one fiber core and a plurality of air holes. Wherein the protective layer wraps the outer wrapping layer, the outer wrapping layer wraps the inner wrapping layer, and the inner wrapping layer wraps the at least one fiber core and the plurality of air holes. The protection layer protects the optical fiber and isolates the environment, improves the mechanical strength of the optical fiber and prolongs the service life of the optical fiber. The at least one fiber core and the plurality of air holes extend in the same direction, the fiber core is used for transmitting signal light, each air hole is filled with a quantum dot solution, and the quantum dot solution is used for absorbing pump light coupled to the gain fiber. The plurality of air holes are distributed around the fiber core, that is, the air holes are closer to the edge of the inner cladding than the fiber core. And the refractive index of the fiber core is greater than that of the inner cladding, so that the signal light is transmitted in the fiber core in a low-loss single mode. The refractive index of the inner cladding is greater than that of the outer cladding.

Description

Technical Field

[0001] The present application relates to the field of optical fibers, and in particular to a gain optical fiber and an optical amplification device. Background Art

[0002] As the demand for optical communication network capacity continues to increase, the wavelength division multiplexing system makes full use of the huge bandwidth resources brought by single-mode optical fiber to achieve ultra-large capacity information transmission. Although single-mode optical fiber has extremely low transmission loss, when the signal light transmission length reaches tens or hundreds of kilometers, the transmission loss of optical fiber can no longer be ignored. Therefore, optical amplifiers are needed in optical communication networks to compensate for the signal light power and gain amplification.

[0003] Among them, reducing the noise coefficient of optical amplifiers is one of the keys to improving the optical signal to noise ratio (OSNR) of wavelength division multiplexing systems, especially in backbone long-distance optical communication networks, where low-noise optical amplifier solutions are urgently needed. Existing erbium-doped fiber amplifiers (EDFA) use stimulated radiation of erbium ions in the core of erbium-doped gain fibers to achieve high gain and low noise amplification of signal light. However, due to the large overlap of the absorption and emission cross sections of erbium ions, the noise coefficient of erbium-doped fiber amplifiers is relatively large, and the industry is in urgent need of developing new low-noise optical amplifier technologies. Summary of the invention

[0004] The embodiments of the present application provide a gain optical fiber and an optical amplifier device, which can achieve optical amplification performance with high gain and low noise coefficient.

[0005] In a first aspect, an embodiment of the present application provides a gain optical fiber. The gain optical fiber comprises: a protective layer, an inner cladding, at least one fiber core and a plurality of air holes. The protective layer wraps the inner cladding, and the inner cladding wraps at least one fiber core and a plurality of air holes. The protective layer protects the optical fiber and isolates it from the environment, thereby improving the mechanical strength and service life of the optical fiber. At least one fiber core and a plurality of air holes extend in the same direction, the fiber core is used to transmit signal light, and each air hole is filled with a quantum dot solution, which is used to absorb the pump light coupled to the gain optical fiber. A plurality of air holes are distributed around the fiber core, that is, the air holes are closer to the edge of the inner cladding than the fiber core. The refractive index of the fiber core is greater than the refractive index of the inner cladding, so that the signal light is transmitted in a low-loss single-mode manner in the fiber core.

[0006] In this embodiment, using quantum dots as gain media can make the noise coefficient of the optical amplifier closer to the theoretical noise limit, so that high gain and low noise coefficient optical amplifier performance can be obtained. Different from the interior of the core in which erbium ions are usually doped in the existing scheme, the air holes 5 filled with quantum dot solution in the gain optical fiber of the present application are distributed around the core 4, which is conducive to the decomposition and performance degradation of the quantum dots. In addition, sealing the quantum dot solution inside the optical fiber helps to isolate the quantum dots from the external environment and avoid the instability and decomposition of the quantum dots during long-term operation. In addition, air holes filled with quantum dot solution are arranged around the core, which can effectively avoid the introduction of additional defects into the quantum dots, and is also conducive to improving the filling efficiency of the quantum dot solution and reducing the preparation cost.

[0007] In some possible implementations, the gain fiber further includes an outer cladding, the protective layer wraps the outer cladding, the outer cladding wraps the inner cladding, and the refractive index of the inner cladding is greater than the refractive index of the outer cladding. This implementation uses a double-clad optical fiber, which is more suitable for cladding pumping application scenarios.

[0008] In some possible implementations, the pump light is injected into the outer cladding, the refractive index of the inner cladding is greater than the refractive index of the outer cladding, the outer cladding constitutes a total reflection condition for the pump light, and the pump light is transmitted by reflection in the outer cladding. Since the air holes filled with quantum dot solution are distributed around the core, the pump light will repeatedly pass through the core and the air holes during transmission. After the pump light is absorbed by the quantum dots, a particle number inversion is formed to achieve gain amplification of the signal light. It should be understood that the implementation method of cladding pumping can decouple the transmission paths of the signal light and the pump light, and compared with the core pumping method, it can improve the pumping efficiency of the pump light to the quantum dots, thereby reducing the pumping cost. In addition, since the pump light is mainly transmitted back and forth in the outer cladding to excite the quantum dots in the air holes, the pump power per unit area of ​​the quantum dots is low, which can improve the service life of the quantum dots and avoid the decomposition and performance degradation of the quantum dots caused by long-term use of pump light.

[0009] In some possible implementations, the refractive index of the quantum dot solution filled in the air hole matches the refractive index of the fiber core, that is, the refractive index of the quantum dot solution is equal to the refractive index of the fiber core, or the refractive index of the quantum dot solution is slightly greater than the refractive index of the fiber core. In this way, the light field distribution of the signal light not only covers the fiber core, but also covers multiple air holes, expanding the coverage range of the light field.

[0010] In some possible implementations, the signal light interacts with the quantum dots through the evanescent field. In order to enhance the interaction strength between the quantum dots and the signal light, the air hole should be placed as close to the core as possible, that is, the minimum distance between the air hole and the core is smaller than the minimum distance between the air hole and the edge of the inner cladding.

[0011] In some possible implementations, the multiple air holes are symmetrically distributed relative to the fiber core, thereby achieving a quasi-polarization-maintaining effect, which is beneficial for ensuring that the linear polarization direction of the signal light remains unchanged and improving the coherent signal-to-noise ratio.

[0012] In some possible implementations, the distance between each air hole and the fiber core is equal, so that the interaction intensity between each quantum dot and the signal light is more balanced, which is conducive to achieving a better amplification effect on the signal light.

[0013] In some possible implementations, the distance between each two adjacent air holes in the plurality of air holes is equal. In other words, the plurality of air holes are distributed at equal intervals, so that the overall distribution of the plurality of air holes is more uniform, which is conducive to achieving uniform amplification of the signal light.

[0014] In some possible implementations, the diameter of the fiber core is larger than the diameter of the air holes, so as to better distribute the multiple air holes around the fiber core.

[0015] In some possible implementations, the shape of the inner cladding is a regular polygon, for example, a regular octagon, etc., which is beneficial to improving the gain amplification effect of the gain fiber.

[0016] In some possible embodiments, the solvent in the quantum dot solution includes one of toluene, chlorobenzene and dichlorobenzene, and the quantum dots in the quantum dot solution include lead sulfide PbS, lead selenide PbSe, or a core-shell structure of PbS and PbSe. It should be understood that the choice of solvent is based on actual needs, and the interaction intensity between the quantum dots and the signal light can be adjusted by changing the solvent of the quantum dot solution.

[0017] In some possible embodiments, the concentration of the quantum dot solution is greater than or equal to 0.001% and less than or equal to 20%.

[0018] In a second aspect, an embodiment of the present application provides an optical amplifier device, which includes: a signal light source, a pump light source, a wavelength division multiplexer, a first isolator, a second isolator, and a gain fiber as described in any embodiment of the first aspect. The signal light source is used to emit signal light. The pump light source is used to emit pump light. The wavelength division multiplexer 0 is used to combine the signal light and the pump light into a single path for transmission to the gain fiber. The first isolator and the second isolator are used to isolate the echo reflected light generated by the signal light transmission, thereby ensuring that the signal light has a single transmission direction.

[0019] In some possible implementations, the optical amplification device further includes a single-mode optical fiber, and both ends of the gain optical fiber are fused with the single-mode optical fiber. The single-mode optical fiber is a single-clad optical fiber, the core of the single-mode optical fiber is butted with the core of the gain optical fiber, and the signal light is transmitted to the core of the gain optical fiber through the core of the single-mode optical fiber.

[0020] In some possible implementations, the transmission directions of the pump light and the signal light may be the same or opposite, so as to adapt to a variety of different application scenarios.

[0021] In the gain optical fiber provided in the embodiment of the present application, a plurality of air holes are distributed around the core, and each air hole is filled with a quantum dot solution. The signal light is transmitted in the core, and the pump light coupled to the gain optical fiber is used to excite the quantum dots in the air holes to achieve a population inversion to achieve a gain amplification of the signal light. It should be understood that the use of quantum dots as a gain medium can make the noise coefficient of the optical amplifier closer to the theoretical noise limit, so that a high gain and low noise coefficient optical amplifier performance can be obtained. In addition, sealing the quantum dot solution inside the optical fiber helps to isolate the quantum dots from the external environment and avoid the instability and decomposition of the quantum dots during long-term operation. In addition, air holes filled with quantum dot solution are arranged around the core, which can effectively avoid the introduction of additional defects into the quantum dots, and is also conducive to improving the filling efficiency of the quantum dot solution and reducing the preparation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of a first cross section of a gain optical fiber in an embodiment of the present application;

[0023] Figure 2 This is a second cross-sectional schematic diagram of the gain optical fiber in the embodiment of the present application;

[0024] Figure 3 This is a schematic diagram of the light field distribution of the signal light in the embodiment of the present application;

[0025] Figure 4 A schematic diagram of cladding pumping in an embodiment of the present application;

[0026] Figure 5 This is a third cross-sectional schematic diagram of the gain optical fiber in the embodiment of the present application;

[0027] Figure 6 This is a fourth cross-sectional schematic diagram of the gain optical fiber in the embodiment of the present application;

[0028] Figure 7 This is a fifth cross-sectional schematic diagram of the gain optical fiber in the embodiment of the present application;

[0029] Figure 8 This is a sixth cross-sectional schematic diagram of the gain optical fiber in the embodiment of the present application;

[0030] Fig. 9 This is a seventh cross-sectional schematic diagram of the gain optical fiber in the embodiment of the present application;

[0031] Fig.10 A schematic diagram of the structure of an optical amplifying device in an embodiment of the present application;

[0032] Fig.11 FIG. 4 is another schematic diagram of the structure of the optical amplification device in an embodiment of the present application. DETAILED DESCRIPTION

[0033] The embodiments of the present application provide a gain optical fiber and an optical amplifier device, which can obtain optical amplifier performance with high gain and low noise coefficient. It should be understood that the present application can be applied in backbone long-distance optical communication networks, and the main use scenario is low-noise optical amplifier devices in optical communication networks. It can also be used in short-distance optical communication networks and lasers.

[0034] It should be noted that the terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, rather than to limit a specific order or precedence. It should be understood that the above terms can be interchanged where appropriate, so that the embodiments described in this application can be implemented in a sequence other than the content described in this application. 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 units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0035] The gain optical fiber provided in the present application utilizes quantum dots (Quantum Dots, QDs) doping to achieve gain amplification of signal light. It should be understood that since the size of quantum dots in three dimensions is nanometer-level, the electron motion inside it is restricted, thereby reflecting the atomic electronic structure and the energy level related to the size and giving quantum dots unique physical properties. Compared with erbium ions, quantum dots of different sizes have different fluorescence spectra and absorption spectra. Thanks to the fact that quantum dots can stagger the absorption cross section and the emission cross section through the quantum confinement effect, it is helpful to make the noise coefficient of the optical amplifier using quantum dots as the gain medium closer to the theoretical noise limit. In addition, the quantum dot band gap energy is small, the Bohr radius of the exciton is large, and the fluorescence wavelength can be regulated in the visible light to mid-infrared band, so the fluorescence wavelength of quantum dots is expected to cover the main optical communication window, so that the optical amplifier using quantum dots as the gain medium has broad application prospects and greater application value in the field of communication.

[0036] Figure 1 Schematic diagram of the first cross section of the gain optical fiber in the embodiment of the present application. Figure 1 As shown, the gain optical fiber includes: a protective layer 1, an outer cladding 2, an inner cladding 3, a core 4 and a plurality of air holes 5. The protective layer 1 wraps the outer cladding 2, the outer cladding 2 wraps the inner cladding 3, and the inner cladding 3 wraps the core 4 and the plurality of air holes 5. The protective layer 1 protects the optical fiber and isolates the environment, thereby improving the mechanical strength and service life of the optical fiber.

[0037] The core 4 and the multiple air holes 5 extend in the same direction. The core 4 is used to transmit signal light. Each air hole is filled with a quantum dot solution, and the quantum dot solution is used to absorb the pump light coupled to the gain fiber. The refractive index of the core 4 is greater than the refractive index of the inner cladding 3, so that the signal light is transmitted in the core 4 in a low-loss single-mode. The multiple air holes 5 are distributed around the core 4, that is, the air holes 5 are closer to the edge of the inner cladding 3 than the core 4. It should be understood that, unlike the interior of the core in the existing scheme where erbium ions are usually doped, the air holes 5 filled with quantum dot solutions in the gain fiber of the present application are distributed around the core 4, which is conducive to the decomposition and performance degradation of the quantum dots. In addition, sealing the quantum dot solution inside the optical fiber helps to isolate the quantum dots from the external environment and avoid the instability and decomposition of the quantum dots during long-term operation.

[0038] Figure 2 This is a second cross-sectional schematic diagram of the gain optical fiber in the embodiment of the present application. It should be understood that the number of fiber cores can be one or more, and the present application does not limit the specific number of fiber cores. For example, Figure 1 Shown is a possible implementation of a single fiber core. Figure 2 What is shown is a possible implementation of a multi-core. In practical applications, whether it is a single core or a multi-core, the number of air holes 5 should be greater than the number of cores 4, and the diameter of the core 4 should be greater than the diameter of the air holes 5, so that the multiple air holes 5 can be better distributed around the core 4.

[0039] Figure 3 Schematic diagram of the light field distribution of the signal light in the embodiment of the present application. Figure 3 As shown, the optical field distribution of the signal light not only covers the fiber core 4, but also covers multiple air holes 5, thus expanding the coverage of the optical field. In other words, the fiber core 4 and multiple air holes 5 can be considered to together constitute the core of the gain fiber. Figure 3 The light field distribution shown requires that the refractive index of the quantum dot solution filled in the air hole 5 matches the refractive index of the core 4, that is, the refractive index of the quantum dot solution is equal to the refractive index of the core 4, or the refractive index of the quantum dot solution is slightly greater than the refractive index of the core 4. It should be understood that the signal light interacts with the quantum dots through the evanescent field. In order to enhance the interaction intensity between the quantum dots and the signal light, the air hole 5 should be set as close to the core as possible, that is, the minimum distance between the air hole 5 and the core 4 is less than the minimum distance between the air hole 5 and the edge of the inner cladding 3. It should also be understood that in practical applications, the interaction intensity between the quantum dots and the signal light can be adjusted by adjusting the distance between the air hole 5 and the core 4. Therefore, the distance between the air hole 5 and the core 4 should be based on actual needs and is not limited here.

[0040] In some possible implementations, the gain optical fiber provided in the present application can be adapted to both core pumping and cladding pumping. That is, the pump light can be injected into the core 4 or into the outer cladding 2. It should be understood that the transmission directions of the pump light and the signal light can be the same or opposite, so as to adapt to a variety of different application scenarios.

[0041] Figure 4 This is a schematic diagram of cladding pumping in the embodiment of the present application. As an example, preferably, an implementation method of injecting pump light into the outer cladding 2 is adopted, the refractive index of the inner cladding 3 is greater than the refractive index of the outer cladding 2, the outer cladding 2 constitutes a total reflection condition for the pump light, and the pump light is transmitted by reflection in the outer cladding 2. Since the air holes filled with quantum dot solution are distributed around the core 4, the pump light will repeatedly pass through the core 4 and the air holes 5 during the transmission process. After the pump light is absorbed by the quantum dots, a particle number inversion is formed to achieve the gain amplification of the signal light. It should be understood that the implementation method of cladding pumping can decouple the transmission paths of the signal light and the pump light, and compared with the core pumping method, it can improve the pumping efficiency of the pump light to the quantum dots, thereby reducing the pumping cost. In addition, since the pump light is mainly transmitted back and forth in the outer cladding 2 to excite the quantum dots in the air holes 5, the pump power per unit area of ​​the quantum dots is low, which can improve the service life of the quantum dots and avoid the decomposition and performance degradation of the quantum dots caused by long-term use of the pump light.

[0042] Figure 5 FIG. 4 is a schematic diagram of a third cross section of the gain fiber in the embodiment of the present application. As another example, if the pump light is injected into the core 4, the signal light and the pump light can interact with the quantum dots in the air hole 5 through the evanescent field, thereby achieving gain amplification of the signal light. It should be understood that in this application scenario of core pumping, the gain fiber can be used as follows: Figure 1 The double-clad optical fiber shown in FIG. Figure 5 Single-clad optical fiber shown. Figure 5 and Figure 1 The difference is that Figure 5 The gain fiber shown includes only the inner cladding 3 but not the outer cladding 2 .

[0043] In some possible embodiments, the solvent in the quantum dot solution includes one of toluene, chlorobenzene and dichlorobenzene. The quantum dots in the quantum dot solution include lead sulfide PbS, lead selenide PbSe, or a core-shell structure of PbS and PbSe. The concentration of the quantum dot solution is greater than or equal to 0.001% and less than or equal to 20%. Specifically, the quantum dot solution can be uniformly filled into the air hole by siphoning and a pressure pump, wherein the pressure pump is used to provide a pressure difference on both sides of the gain fiber to achieve long-distance uniform filling of the quantum dot solution in the air hole of the gain fiber. It should be understood that the choice of solvent is based on actual needs, and the intensity of the interaction between the quantum dots and the signal light can be regulated by changing the solvent of the quantum dot solution.

[0044] It should be noted that the present application does not limit the specific distribution of the multiple air holes 5, and several possible distributions of the multiple air holes 5 are provided below. For ease of introduction, the gain fiber will be introduced below using a single core as an example, and the distribution of the air holes 5 in the multi-core structure can be achieved by referring to the distribution of the air holes 5 in the single core structure.

[0045] Figure 6 FIG. 4 is a schematic diagram of a fourth cross-section of a gain optical fiber in an embodiment of the present application. Figure 6 As shown, the multiple air holes 5 are symmetrically distributed relative to the fiber core 4, so as to achieve a polarization-maintaining effect, which is beneficial to ensure that the linear polarization direction of the signal light remains unchanged and improve the coherent signal-to-noise ratio.

[0046] Figure 7 FIG. 5 is a schematic diagram of the fifth cross section of the gain optical fiber in the embodiment of the present application. Figure 7 As shown, the distance between each air hole 5 and the fiber core 4 is equal, so that the interaction intensity between each quantum dot and the signal light is more balanced, which is conducive to achieving a better amplification effect on the signal light.

[0047] Figure 8 FIG. 6 is a sixth cross-sectional schematic diagram of the gain optical fiber in the embodiment of the present application. Figure 8 As shown, the distance between every two adjacent air holes in the plurality of air holes 5 is equal. In other words, the plurality of air holes 5 are distributed at equal intervals, so that the overall distribution of the plurality of air holes 5 is more uniform, which is conducive to achieving uniform amplification of the signal light.

[0048] Preferably, if the plurality of air holes 5 simultaneously meet the above Figure 6-Figure 8 For the distribution method introduced, please refer to Figure 1 The structure shown. That is, Figure 1 The gain fiber shown can not only play a quasi-polarization-maintaining effect, but also make the interaction intensity between each quantum dot and the signal light more balanced, and is conducive to achieving uniform amplification of the signal light.

[0049] It should be noted that the present application does not limit the specific structural parameters of the gain optical fiber, and a possible implementation method is provided below.

[0050] Fig. 9 FIG. 7 is a schematic diagram of the seventh cross section of the gain optical fiber in the embodiment of the present application. Fig. 9 As shown, the diameter of the core 4 is 7.8 μm, the distance between the center of the air hole 5 and the center of the core 4 is 4.4 μm, the distance between the centers of each two adjacent air holes 5 is 1.5 μm, and the diameter of the air hole 5 is 1 μm. The edge profile of the inner cladding 3 is a regular octagon, which is beneficial to improving the gain amplification effect of the gain optical fiber. The length of the regular octagon is 25±3 μm. In practical applications, the edge profile of the inner cladding 3 can also adopt other shapes such as a regular hexagon. The diameter of the outer cladding 2 is 125±3 μm, and the diameter of the protective layer 1 is 245±3 μm.

[0051] From the above introduction to the gain fiber, it can be seen that there are multiple air holes distributed around the core, and each air hole is filled with a quantum dot solution. The signal light is transmitted in the core, and the pump light coupled to the gain fiber is used to excite the quantum dots in the air hole to achieve a population inversion to achieve a gain amplification of the signal light. It should be understood that the use of quantum dots as a gain medium can make the noise coefficient of the optical amplifier closer to the theoretical noise limit, so that high gain and low noise coefficient optical amplifier performance can be obtained. Different from the core of the fiber usually doped with erbium ions in the existing scheme, the air holes 5 filled with quantum dot solution in the gain fiber of the present application are distributed around the core 4, which is conducive to the decomposition and performance degradation of the quantum dots. In addition, sealing the quantum dot solution inside the optical fiber helps to isolate the quantum dots from the external environment and avoid the instability and decomposition of the quantum dots during long-term operation. In addition, the air holes filled with quantum dot solution are arranged around the core, which can effectively avoid the introduction of additional defects to the quantum dots, and is also conducive to improving the filling efficiency of the quantum dot solution and reducing the preparation cost.

[0052] Based on the gain optical fiber introduced in the above embodiment, the present application also provides an optical amplification device, which is described in detail below.

[0053] Fig.10 FIG. 1 is a schematic diagram of a structure of an optical amplification device in an embodiment of the present application. Fig.10As shown, the optical amplification device includes: a signal light source 10, a pump light source 20, a wavelength division multiplexer 30, a first isolator 40, a second isolator 50 and a gain fiber 60. Among them, the gain fiber 60 can be the gain fiber introduced in any of the above embodiments. The signal light source 10 is used to emit signal light. The pump light source 20 is used to emit pump light. The wavelength division multiplexer 30 is used to combine the signal light and the pump light into a single path for transmission to the gain fiber 60. The first isolator 40 and the second isolator 50 are used to isolate the echo reflected light generated by the signal light transmission, so as to ensure that the signal light has a single transmission direction. Among them, the first isolator 40 and the second isolator 50 can adopt polarization-independent isolators.

[0054] In some possible implementations, such as Fig.10 As shown, the optical amplification device further includes a single-mode optical fiber 70, and both ends of the gain optical fiber 60 are fused with the single-mode optical fiber 70. The single-mode optical fiber 70 is a single-clad optical fiber, and the core of the single-mode optical fiber 70 is butted with the core of the gain optical fiber 60, and the signal light is transmitted to the core of the gain optical fiber 60 through the core of the single-mode optical fiber 70.

[0055] Fig.11 FIG. 1 is another schematic diagram of the structure of the optical amplifier device in the embodiment of the present application. It should be understood that Fig.10 The embodiment shown is that the signal light and the pump light have the same transmission direction, and the signal light source 10 , the pump light source 20 and the wavelength division multiplexer 30 are located on the same side of the gain optical fiber 60 . Fig.11 The embodiment shown is that the signal light and the pump light are transmitted in opposite directions, such as Fig.11 As shown, the signal light source 10 is located on one side of the gain fiber 60, and the pump light source 20 and the wavelength division multiplexer 30 are located on the other side of the gain fiber 60. The wavelength division multiplexer 30 couples the pump light into the gain fiber 60 for reverse transmission with the signal light.

[0056] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A gain optical fiber, characterized in that: include: A protective layer, an inner cladding, at least one fiber core and a plurality of air holes, wherein the protective layer wraps the inner cladding, the inner cladding wraps the at least one fiber core and the plurality of air holes, the at least one fiber core and the plurality of air holes extend in the same direction, each of the air holes is filled with a quantum dot solution, the air hole is closer to the edge of the inner cladding than the fiber core, the refractive index of the fiber core is greater than the refractive index of the inner cladding, the fiber core is used to transmit signal light, and the quantum dot solution is used to absorb pump light coupled to the gain fiber.

2. The gain optical fiber according to claim 1, characterized in that: The gain optical fiber further includes an outer cladding, the protective layer wraps the outer cladding, the outer cladding wraps the inner cladding, and the refractive index of the inner cladding is greater than the refractive index of the outer cladding.

3. The gain optical fiber according to claim 2, characterized in that: The pump light is transmitted in the outer cladding by reflection.

4. The gain optical fiber according to any one of claims 1 to 3, characterized in that: The refractive index of the quantum dot solution is greater than or equal to the refractive index of the fiber core.

5. The gain optical fiber according to any one of claims 1 to 4, characterized in that: A minimum distance between the air hole and the core is smaller than a minimum distance between the air hole and an edge of the inner cladding.

6. The gain optical fiber according to any one of claims 1 to 5, characterized in that: The gain optical fiber includes a core, and the multiple air holes are symmetrically distributed relative to the core.

7. The gain optical fiber according to any one of claims 1 to 6, characterized in that: The gain optical fiber includes a core, and the distance between each of the air holes and the core is equal.

8. The gain optical fiber according to any one of claims 1 to 7, characterized in that: The gain optical fiber includes a core, and the distance between every two adjacent air holes in the plurality of air holes is equal.

9. The gain optical fiber according to any one of claims 1 to 8, characterized in that: The number of the air holes is greater than the number of the fiber cores.

10. The gain optical fiber according to any one of claims 1 to 9, characterized in that: The diameter of the fiber core is greater than the diameter of the air hole.

11. The gain optical fiber according to any one of claims 1 to 10, characterized in that: The inner cladding is in the shape of a regular polygon.

12. The gain optical fiber according to any one of claims 1 to 11, characterized in that: The solvent in the quantum dot solution includes one of toluene, chlorobenzene and dichlorobenzene, and the quantum dots in the quantum dot solution include lead sulfide PbS, lead selenide PbSe or a core-shell structure of PbS and PbSe.

13. The gain optical fiber according to any one of claims 1 to 12, characterized in that: The concentration of the quantum dot solution is greater than or equal to 0.001% and less than or equal to 20%.

14. An optical amplification device, characterized in that: include: A signal light source, a pump light source, a wavelength division multiplexer, a first isolator, a second isolator, and a gain optical fiber as claimed in any one of claims 1 to 13; The signal light source is used to emit signal light; The pump light source is used to emit pump light; The first isolator and the second isolator are used to isolate the echo reflected light generated by the signal light transmission; The wavelength division multiplexer is used to couple the signal light and the pump light to the gain optical fiber.

15. The optical amplifying device according to claim 14, characterized in that: The optical amplification device further comprises a single-mode optical fiber, and two ends of the gain optical fiber are fused to the single-mode optical fiber.

16. The optical amplifying device according to claim 14 or 15, characterized in that: The transmission direction of the signal light is the same as the transmission direction of the pump light, or the transmission direction of the signal light is opposite to the transmission direction of the pump light.

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