Device for stabilizing output power of pump laser and optical fiber amplifier

Abstract

The utility model relates to the technical field of optical fiber amplifiers, in particular to a device for stabilizing the output power of a pump laser and an optical fiber amplifier. Stray light except pump light signals is absorbed through the first wavelength division multiplexer, the second wavelength division multiplexer and the third wavelength division multiplexer in sequence, so that the effects of stabilizing the output power of the pump laser and stabilizing the output power of signal light in a low-gain optical fiber amplification scene are achieved. In addition, the device needs relatively few special doped fibers, the pumping power consumption is low, the product development cost is reduced to a certain extent, and meanwhile, the device is suitable for the requirements of various amplification scenes and is high in universality.

Description

Technical Field

[0001] The utility model relates to the technical field of optical fiber amplifiers, in particular to a device for stabilizing the output power of a pump laser and an optical fiber amplifier. Background Art

[0002] With the development of fiber amplification technology and the continuous improvement of current business traffic and access capabilities, more and more companies tend to stipulate that the problem of EDFA cascade output power jitter should be reduced as much as possible during the development of Erbium-doped Optical Fiber Amplifier (EDFA) products. For some low-gain amplification scenarios, the amount of pump power used in a single EDFA is small, so the required driving current is low, and may even be lower than the threshold current of the pump laser itself. In this case, the output power of the pump laser itself is relatively unstable, which will greatly affect the gain effect of the signal light after EDFA amplification, especially the output power and output spectrum, making it difficult to meet the requirements for signal light in the transmission network system.

[0003] In view of this, overcoming the defects of the prior art is an urgent problem to be solved in the field of this technology. Utility Model Content

[0004] The technical problem to be solved by the utility model is how to provide a device capable of stabilizing the output power of a pump laser.

[0005] The utility model adopts the following technical solutions:

[0006] In one aspect, a device for stabilizing the output power of a pump laser is provided, comprising: a first wavelength division multiplexer, a doped optical fiber, a second wavelength division multiplexer, and a third wavelength division multiplexer;

[0007] The pump end of the first wavelength division multiplexer is used to connect to the output end of the pump laser;

[0008] The output end of the first wavelength division multiplexer is connected to one end of the doped optical fiber, and the other end of the doped optical fiber is connected to the input end of the second wavelength division multiplexer;

[0009] The output end of the second wavelength division multiplexer is connected to the input end of the third wavelength division multiplexer, and the output end of the third wavelength division multiplexer is used to connect to the pump laser input port of the optical fiber amplifier optical path.

[0010] Preferably, the device further comprises a bevel pin, and the signal input end of the first wavelength division multiplexer is connected to the bevel pin;

[0011] The bevel pin is used to absorb the reverse ASE light generated after the pump light signal emitted by the pump laser enters the doped optical fiber.

[0012] Preferably, the pump ends of the second wavelength division multiplexer and the third wavelength division multiplexer are both connected to winding modes;

[0013] The winding mode is used to consume the reverse amplifier spontaneous emission noise (Amplifier Spontaneous Emission, abbreviated as ASE) light that is filtered out in the optical path.

[0014] Preferably, the length of the doped optical fiber is 0-1 m.

[0015] Preferably, the wavelength of the pump light emitted by the pump laser includes one or more of 940 nm, 980 nm and 1480 nm.

[0016] Preferably, when the wavelength of the pump light emitted by the pump laser is 940 nm, the first wavelength division multiplexer, the second wavelength division multiplexer and the third wavelength division multiplexer are all 940 / 1550 wavelength division multiplexers (Wavelength Division Multiplexing, abbreviated as WDM).

[0017] Preferably, when the wavelength of the pump light emitted by the pump laser is 980 nm, the first wavelength division multiplexer, the second wavelength division multiplexer and the third wavelength division multiplexer all use 980 / 1550 WDM.

[0018] Preferably, when the wavelength of the pump light emitted by the pump laser is 1480 nm, the first wavelength division multiplexer, the second wavelength division multiplexer and the third wavelength division multiplexer all use 1480 / 1550 WDM.

[0019] In a second aspect, a fiber amplifier is provided, the fiber amplifier comprising at least one device for stabilizing the output power of a pump laser, at least one pump laser and a fiber amplifier optical path;

[0020] The pump laser is connected to the pump end of the first wavelength division multiplexer, and the output end of the third wavelength division multiplexer is connected to the pump laser input port of the optical fiber amplifier optical path.

[0021] Preferably, the optical fiber amplifier comprises a bismuth-doped optical fiber amplifier and / or a Raman optical fiber amplifier.

[0022] Compared with the prior art, the beneficial effects of the utility model are:

[0023] The utility model uses a shorter doped optical fiber to pre-attenuate the laser signal emitted by the pump laser in advance, and at the same time, absorbs stray light other than the pump light signal through the first wavelength division multiplexer, the second wavelength division multiplexer and the third wavelength division multiplexer in sequence, so as to achieve the effect of stabilizing the output power of the pump laser and the output power of the signal light in the low-gain fiber amplification scenario. In addition, the device requires relatively few special doped optical fibers, the pump power consumption is low, and the product development cost is reduced to a certain extent. At the same time, the device is suitable for the requirements of various amplification scenarios and has high versatility.

[0024] The solution of the utility model is applicable to similar fiber amplification scenarios, such as a fiber amplifier based on 980nm pumping, a fiber amplifier based on 1480nm pumping, or a fiber amplifier based on 940nm pumping. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 It is a structural schematic diagram of a device for stabilizing the output power of a pump laser provided in an embodiment of the utility model;

[0027] Figure 2 This is a second structural schematic diagram of a device for stabilizing the output power of a pump laser provided by an embodiment of the utility model;

[0028] Figure 3 It is a more specific structural schematic diagram of a device for stabilizing the output power of a pump laser provided by an embodiment of the utility model;

[0029] Figure 4 It is a structural schematic diagram of a fiber optic amplifier provided by an embodiment of the utility model;

[0030] Figure 5 This is another structural schematic diagram of an optical fiber amplifier provided in an embodiment of the utility model. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0032] The terms "first", "second", etc. in this utility model are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of this utility model, unless otherwise specified, "plurality" means two or more.

[0033] In the present invention, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0034] Embodiment 1:

[0035] In order to solve the problem of unstable output power and output spectrum of pump laser under low current scenario in the field of optical amplification application, and to overcome the pain points of EDFA output power jitter caused by pump output power jitter under low gain amplification conditions of traditional EDFA, the embodiment of the utility model proposes a device for stabilizing the output power of pump laser, such as Figure 1 As shown, it includes: a first wavelength division multiplexer (i.e., WDM1), a doped optical fiber, a second wavelength division multiplexer (i.e., WDM2) and a third wavelength division multiplexer (i.e., WDM3); the pump end of the first wavelength division multiplexer is used to connect with the output end of the pump laser; the output end of the first wavelength division multiplexer is connected to one end of the doped optical fiber, and the other end of the doped optical fiber is connected to the input end of the second wavelength division multiplexer; the output end of the second wavelength division multiplexer is connected to the input end of the third wavelength division multiplexer, and the output end of the third wavelength division multiplexer is used to connect with the pump laser input port of the optical path of the optical fiber amplifier.

[0036] The pump light wavelength emitted by the pump laser includes one or more of 940 nm, 980 nm and 1480 nm. A corresponding wavelength division multiplexer is selected according to the specific wavelength, as described below.

[0037] The first wavelength division multiplexer is the entrance of the device, which is used to separate optical signals of multiple wavelengths. In this device, the pump end of the first wavelength division multiplexer is connected to the output end of the pump laser. The pump light signal generated by the pump laser will enter the device through the pump end of the first wavelength division multiplexer. The doped optical fiber contains dopants (such as erbium ions) for absorbing the energy in the pump light signal and pre-attenuating the pump light signal. In a preferred embodiment, the length of the doped optical fiber is 0 to 1m. Specifically, the length of the doped optical fiber depends on the concentration of the dopant in the doped optical fiber, which is generally set within 1m; more specifically, experiments are required to find the relationship between the concentration of the dopant in the doped optical fiber and the attenuation curve, as well as the relationship between the length parameter of the doped optical fiber and the attenuation curve, so as to finally find the concentration and length of the dopant corresponding to the attenuation value of the doped optical fiber.

[0038] One end of the doped optical fiber is connected to the output end of the first wavelength division multiplexer, so that the pump light signal from the pump laser can enter the doped optical fiber. The pump light signal is pre-attenuated in advance by using a shorter doped optical fiber, and then enters the gain optical fiber of the optical fiber amplifier, so as to finally achieve stable output of the signal light power.

[0039] The input end of the second wavelength division multiplexer is connected to the other end of the doped optical fiber, and is used to receive the optical signal transmitted from the doped optical fiber. The function of the second wavelength division multiplexer is to separate the pump optical signal from other signals in the doped optical fiber to maintain the purity of the pump optical signal. The input end of the third wavelength division multiplexer is connected to the output end of the second wavelength division multiplexer, and is used to receive the pump optical signal separated by the second wavelength division multiplexer, and further separate it to finally obtain a pure pump optical signal. The output end of the third wavelength division multiplexer is connected to the pump laser input port of the optical fiber amplifier, and is used to transmit the stable pump optical signal to the optical fiber amplifier for amplification processing of the optical signal.

[0040] In one embodiment, taking a 980nm pump laser as an example, the 980nm pump light power required in the low-gain amplification scenario optical path is relatively low, such as only 10mW, corresponding to a pump drive current of 50mA, and the minimum threshold current of the 980nm pump laser is also 50mA. In this case, the 980nm pump laser is working in an abnormal working state, which means that the output pump light signal is unstable, which is very likely to cause the signal light after amplification of the optical fiber amplifier in a low-gain scenario to be unstable, affecting the normal communication of the link service light. In order to solve the above-mentioned problem, according to the solution of the embodiment of the utility model, a doped optical fiber for fixed attenuation can be connected to the output end of the 980nm pump laser, and the pump drive current (such as 100mA) is increased at the same time, so that the 980nm pump laser can also output 10mW of pump light energy after passing through the doped optical fiber. Then the 980nm pump laser will work under normal working conditions, the output pump light signal will be in a stable state, and the signal light amplified by the fiber amplifier in a low-gain scenario will not be affected by the previous one, thus achieving a stable output effect.

[0041] In a preferred embodiment, in the process of achieving stable output of the 980nm pump laser, the redundant stray light in the optical path is filtered out through three WDMs successively, leaving only the required 980nm pump light, while improving the overall isolation of the optical path, and finally achieving stable output of the 980nm pump light.

[0042] In a preferred embodiment, reference Figure 2 , the device also includes a bevel pin, the signal input end of the first wavelength division multiplexer is connected to the bevel pin; the bevel pin is used to absorb the reverse ASE light generated after the pump light signal emitted by the pump laser enters the doped optical fiber. Among them, the pump light signal will generate reverse ASE light inside the doped optical fiber, that is, unexpected spontaneous radiation. The purpose of setting the bevel pin is to absorb the reverse ASE light generated after the pump light signal enters the doped optical fiber. The bevel pin is set at the signal input end of the first wavelength division multiplexer, and its design adopts a bevel shape, which can effectively absorb the reverse ASE light generated after the pump light signal enters the doped optical fiber to prevent it from affecting the performance of the optical fiber amplifier.

[0043] In a preferred embodiment, reference Figure 3 The pump ends of the second wavelength division multiplexer and the third wavelength division multiplexer are both connected to winding modes; the winding modes are used to consume the ASE light filtered out in the optical path.

[0044] The winding mode is usually a specially designed section of optical fiber, that is, a section of optical fiber is wound into a circle with a smaller radius. Its structure and materials enable it to efficiently absorb and consume unexpected optical noise (for example, ASE light) in the optical signal. In the optical communication system, a certain degree of spontaneous radiation will be generated during the transmission and processing of the optical signal, and these ASE lights will affect the performance and stability of the system. The function of the winding mode is to absorb these ASE lights and convert them into other forms of energy, thereby reducing their interference with the system and ensuring the purity and stability of the optical signal. In the device, the pump ends of the second wavelength division multiplexer and the third wavelength division multiplexer are connected to the winding mode. After the optical signal output from the first wavelength division multiplexer passes through the second wavelength division multiplexer and the third wavelength division multiplexer, the ASE light therein will be absorbed by the winding mode. The purpose of this is to ensure that the optical signal from the pump laser to the fiber amplifier is as pure as possible, reduce the impact of unexpected optical noise, and improve the performance and stability of the system.

[0045] In a preferred embodiment, the wavelength of the pump light emitted by the pump laser includes one or more of 940nm, 980nm and 1480nm. When the wavelength of the pump light emitted by the pump laser is 940nm, the first wavelength division multiplexer, the second wavelength division multiplexer and the third wavelength division multiplexer all use 940 / 1550WDM. When the wavelength of the pump light emitted by the pump laser is 980nm, the first wavelength division multiplexer, the second wavelength division multiplexer and the third wavelength division multiplexer all use 980 / 1550WDM. When the wavelength of the pump light emitted by the pump laser is 1480nm, the first wavelength division multiplexer, the second wavelength division multiplexer and the third wavelength division multiplexer all use 1480 / 1550WDM.

[0046] When the pump light wavelength emitted by the pump laser is 940nm, in order to match this wavelength, the wavelength division multiplexer used is 940 / 1550WDM. This means that these wavelength division multiplexers can separate the 940nm wavelength pump light signal and transmit it to the subsequent doped optical fiber for amplification processing, while retaining the 1550nm wavelength signal to maintain the purity and stability of the signal.

[0047] When the pump light wavelength emitted by the pump laser is 980nm, the selected wavelength division multiplexer is 980 / 1550WDM. This wavelength division multiplexer can separate the 980nm wavelength pump light signal and transmit it to the subsequent doped optical fiber for amplification, while retaining the 1550nm wavelength signal to ensure the stability and purity of the optical signal.

[0048] When the pump light wavelength emitted by the pump laser is 1480nm, the wavelength division multiplexer used is 1480 / 1550WDM. The function of this wavelength division multiplexer is to separate the 1480nm wavelength pump light signal and transmit it to the subsequent doped optical fiber for amplification processing, while maintaining the 1550nm wavelength signal to ensure the stability and purity of the optical signal.

[0049] In summary, different wavelength division multiplexers are selected according to the wavelength of the pump light emitted by the pump laser to ensure that the pump light signal can effectively enter the doped optical fiber for amplification processing while maintaining the stability and purity of the optical signal.

[0050] The following briefly describes this solution by taking the pump laser as a 980nm pump laser as an example.

[0051] Taking the 980nm pump laser as an example, in the scenario of pulsed light amplification, the 980nm pump light power required for the normal operation of the fiber amplifier is relatively small. Instantaneous pumping can reverse the number of particles in the doped fiber to a large level to meet the requirements of light amplification. Then the corresponding 980nm driving current must be very low, even lower than its threshold current.

[0052] Therefore, in order to solve the above problems, in the process of realizing the stable output of 980nm pump, a 980nm pump laser is selected as the pump source of the fiber amplifier, and 980 / 1550WDM is used to make the 980nm pump light output stable. The doped optical fiber used needs to have an optimal length, so that the output optical power of the 980nm pump light does not change with the pump current after the erbium fiber absorbs a certain optical power value, that is, the effect of rated attenuation is achieved. This method can still be applied to the optical amplification scenario of 1480nm pump with low power output requirements, and WDM can use 1480 / 1550WDM. Of course, it can also be applied to the optical amplification scenario of 940nm pump with low power output requirements, and WDM can use 940 / 1550WDM.

[0053] In the process of achieving stable output of the 980nm pump laser in this embodiment, since the doped optical fiber used is shorter, the optical power consumed by the 980nm pump light signal is lower. Therefore, this method is not only applicable to low-gain optical fiber amplification scenarios, but also to high-gain optical fiber amplification application scenarios, and at the same time will not cause more optical power consumption of the 980nm pump light and increase of pump electrical power consumption.

[0054] The utility model uses a shorter doped optical fiber to pre-attenuate the laser signal emitted by the pump laser in advance, and at the same time, absorbs stray light other than the pump light signal through the first wavelength division multiplexer, the second wavelength division multiplexer and the third wavelength division multiplexer in sequence, so as to achieve the effect of stabilizing the output power of the pump laser and the output power of the signal light in the low-gain fiber amplification scenario. In addition, the device requires relatively few special doped optical fibers, the pump power consumption is low, and the product development cost is reduced to a certain extent. At the same time, the device is suitable for the requirements of various amplification scenarios and has high versatility.

[0055] The solution of the utility model is applicable to similar fiber amplification scenarios, such as a fiber amplifier based on 980nm pumping, a fiber amplifier based on 1480nm pumping, or a fiber amplifier based on 940nm pumping.

[0056] Embodiment 2:

[0057] In Example 1, a device for stabilizing the output power of a pump laser is proposed. In this embodiment, a fiber amplifier is proposed. Figure 4 As shown, the fiber amplifier includes at least one device for stabilizing the output power of the pump laser, at least one pump laser and a fiber amplifier optical path; the pump laser is connected to the pump end of the first wavelength division multiplexer, and the output end of the third wavelength division multiplexer is connected to the pump laser input port of the fiber amplifier optical path.

[0058] The pump laser is the pump source of the optical fiber amplifier, which is responsible for injecting energy into the doped optical fiber in the optical path of the optical fiber amplifier to stimulate the optical amplification process. The power of the pump light signal output by the pump laser is stabilized by the device for stabilizing the output power of the pump laser proposed in Example 1, and the stabilized pump light signal is transmitted to the pump laser input port of the optical fiber amplifier optical path.

[0059] In the whole system, the output end of the pump laser is connected to the pump end of the first wavelength division multiplexer, the pump light signal output by the pump laser is absorbed by the device for stabilizing the output power of the pump laser and the power is stabilized, and the stabilized pump light signal is transmitted to the optical path of the optical fiber amplifier. The optical path of the optical fiber amplifier includes components such as doped optical fiber and an amplification section, and the doped optical fiber is usually an optical fiber doped with rare earth ions, which is used to amplify the optical signal.

[0060] In a preferred embodiment, reference Figure 5, the fiber amplifier includes a bismuth-doped fiber amplifier and / or a Raman fiber amplifier. Wherein, the pump laser input port of the bismuth-doped fiber amplifier is connected to the output end of the third wavelength division multiplexer in at least one device for stabilizing the output power of the pump laser; the pump laser input port of the Raman fiber amplifier is connected to the output end of the third wavelength division multiplexer in at least one device for stabilizing the output power of the pump laser. A bismuth-doped fiber amplifier is a device that uses an optical fiber doped with bismuth ions for amplification. Bismuth is a commonly used doping element that can effectively enhance the amplification effect of a fiber amplifier, especially in the case of a wide wavelength range. Bismuth-doped fiber amplifiers are generally used to amplify optical signals with a wide wavelength range, such as the near-infrared band, and have good amplification efficiency and stability. A Raman fiber amplifier is a device that uses the Raman scattering effect to amplify optical signals. By introducing an appropriate pump light signal into the optical fiber, Raman scattering amplification of the optical signal can be achieved, thereby enhancing the intensity of the optical signal. In the preferred embodiment provided, the bismuth-doped fiber amplifier and the Raman fiber amplifier may be used in different application scenarios to meet the system's requirements for amplification wavelength range and performance. Their combination can effectively improve the amplification efficiency and performance of fiber amplifier systems and meet the needs of specific applications.

[0061] The structure of the optical fiber amplifier optical path will not be described in detail in this embodiment.

[0062] For the specific structure of the device for stabilizing the output power of the pump laser, please refer to Example 1, which will not be described in detail in this embodiment.

[0063] Embodiment 3:

[0064] In Example 1, a device for stabilizing the output power of a pump laser is proposed. In this embodiment, a method for stabilizing the output power of a pump laser is proposed, taking a 980nm pump laser as an example, comprising:

[0065] Step 1: First, connect the output end of the 980nm pump laser to the pump end of WDM1, and then the 980nm pump light signal enters the shorter doped fiber. The doped fiber is used to absorb and attenuate the pump light signal output by the 980nm pump laser. At the same time, the bevel pin is connected to the signal input end of WDM1 to absorb the reverse ASE generated after the 980nm pump light signal enters the doped fiber.

[0066] Step 2: After the doped optical fiber, WDM2 and WDM3 are added in sequence to filter out light other than the 980nm pump optical signal and increase the isolation of the 980nm pump optical signal in the optical path. Finally, the attenuated 980nm pump optical signal is output.

[0067] Step 3: In order to save the cost of pump use and the power consumption of the amplifier itself as much as possible, the driving current of the 980nm pump laser can be appropriately increased according to the PI curve of the 980nm pump laser in the early stage, and then the output 980nm pump light signal is attenuated in the optical path to achieve the effect of stabilizing the output power of the pump laser and the output power of the signal light in the low-gain fiber amplification scenario.

[0068] For the specific structure of the device for stabilizing the output power of the pump laser, please refer to Example 1, which will not be described in detail in this embodiment.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for stabilizing the output power of a pump laser, characterized in that: include: A first wavelength division multiplexer, a doped optical fiber, a second wavelength division multiplexer, and a third wavelength division multiplexer; The pump end of the first wavelength division multiplexer is used to connect to the output end of the pump laser; The output end of the first wavelength division multiplexer is connected to one end of the doped optical fiber, and the other end of the doped optical fiber is connected to the input end of the second wavelength division multiplexer; The output end of the second wavelength division multiplexer is connected to the input end of the third wavelength division multiplexer, and the output end of the third wavelength division multiplexer is used to connect to the pump laser input port of the optical fiber amplifier optical path.

2. The device for stabilizing the output power of a pump laser according to claim 1, characterized in that: The device further comprises an inclined pin, and the signal input end of the first wavelength division multiplexer is connected to the inclined pin; The bevel pin is used to absorb the reverse ASE light generated after the pump light signal emitted by the pump laser enters the doped optical fiber.

3. The device for stabilizing the output power of a pump laser according to claim 1, characterized in that: The pump ends of the second wavelength division multiplexer and the third wavelength division multiplexer are both connected to winding modes; The winding mode is used to consume the ASE light filtered out in the optical path.

4. The device for stabilizing the output power of a pump laser according to claim 1, characterized in that: The length of the doped optical fiber is 0-1m.

5. The device for stabilizing the output power of a pump laser according to claim 1, characterized in that: The pump light wavelength emitted by the pump laser includes one or more of 940 nm, 980 nm and 1480 nm.

6. The device for stabilizing the output power of a pump laser according to claim 5, characterized in that: When the wavelength of the pump light emitted by the pump laser is 940 nm, the first wavelength division multiplexer, the second wavelength division multiplexer and the third wavelength division multiplexer all use 940 / 1550 WDM.

7. The device for stabilizing the output power of a pump laser according to claim 5, characterized in that: When the wavelength of the pump light emitted by the pump laser is 980 nm, the first wavelength division multiplexer, the second wavelength division multiplexer and the third wavelength division multiplexer all use 980 / 1550 WDM.

8. The device for stabilizing the output power of a pump laser according to claim 5, characterized in that: When the wavelength of the pump light emitted by the pump laser is 1480 nm, the first wavelength division multiplexer, the second wavelength division multiplexer and the third wavelength division multiplexer all use 1480 / 1550 WDM.

9. An optical fiber amplifier, characterized in that: The optical fiber amplifier comprises at least one device for stabilizing the output power of a pump laser as claimed in any one of claims 1 to 8, at least one pump laser and an optical fiber amplifier optical path; The pump laser is connected to the pump end of the first wavelength division multiplexer, and the output end of the third wavelength division multiplexer is connected to the pump laser input port of the optical fiber amplifier optical path.

10. The optical fiber amplifier according to claim 9, characterized in that: The optical fiber amplifier includes a bismuth-doped optical fiber amplifier and / or a Raman optical fiber amplifier.

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