Wavelength-adaptive optical fiber amplification system
Through the wavelength-adaptive fiber amplification system, the signal light is divided into long-wave and short-wave paths, and adaptive gain-matched amplification is performed on each path. This solves the problem of inconsistent gain of broadband optical signals under high power, and achieves improved flatness of the optical signal and receiver performance.
Patent Information
- Application Number
- CN202422871849.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-22
- Publication Date
- 2025-09-26
- Estimated Expiration
- 2034-11-22
AI Technical Summary
Under high-power amplification requirements, the problem of inconsistent signal gains at different wavelengths in broadband optical signals leads to poor signal detection performance at the receiver.
A wavelength-adaptive fiber amplification system is used to divide the signal light into long-wave and short-wave paths through an input wavelength division multiplexer, and amplify them respectively through different erbium-ytterbium co-doped fiber amplification paths. Cladding pumping is used to achieve adaptive gain matching of the signal light.
It improves the flatness of broadband optical signals after high-power amplification, improves the gain consistency of signals of different wavelengths, and enhances the signal detection effect of the receiver.
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Figure CN223390941U_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the field of optical fiber communication technology, and more specifically, relates to a wavelength-adaptive optical fiber amplification system. Background Art
[0002] With the continuous development of space technology, the role of space laser communications in global communications is becoming increasingly prominent. Space laser communication is a technical means of achieving communication in free space using lasers as carrier waves. Lasers have excellent beam characteristics such as good monochromaticity, strong directionality, and high power density. Using laser beams as carrier waves can transmit images, voice, signals, and other information between the satellite and the ground in real time. Compared with traditional microwave communications, space laser communications have the advantages of high transmission rates, strong anti-interference capabilities, small system terminal size, light weight, and low power consumption, making it the preferred solution for intersatellite networking. Space transmission laser communications usually involve two laser communication machines, which transmit modulated laser pulse signals to each other and receive and demodulate the laser transmission signals from each other to achieve duplex communication.
[0003] The transmitting laser is the main part of the laser communication system, and its quality directly affects the communication quality and communication distance. Space optical communication has a long transmission distance, and the atmosphere has a large loss on the laser communication band. Therefore, a high-signal-power laser is needed to effectively solve the problem of optical signal power attenuation during the communication process. At present, the output power of directly modulated lasers is mostly in the milliwatt range. In order to achieve long-distance laser communication, high-power laser emission is required, and erbium-ytterbium fiber amplifiers are usually used to amplify the output power of the laser. Under the requirements of high-power amplification, erbium-ytterbium co-doped optical fiber has the phenomenon of uneven gain. When the wavelengths of the communication signals are far apart, the problem of signal power consistency of multiple wavelengths cannot be met. At the same time, as the output target power changes, the difference in signal power between different wavelengths will further deteriorate, seriously affecting the signal detection of the receiver. Utility Model Content
[0004] In response to the above defects or improvement needs of the existing technology, the present application provides a wavelength-adaptive optical fiber amplification system, which aims to solve the current technical problem of inconsistent gain of different wavelength signals in broadband optical signals under high power amplification requirements.
[0005] To achieve the above objectives, the present application provides a wavelength-adaptive optical fiber amplification system, which includes an input wavelength division multiplexer, a short-wavelength amplification optical path, a long-wavelength amplification optical path, and an output wavelength division multiplexer. After the signal light enters the input wavelength division multiplexer, it is divided into long-wavelength signal light and short-wavelength signal light. The long-wavelength signal light enters the long-wavelength amplification optical path and is amplified by cladding pumping. The short-wavelength signal light enters the short-wavelength amplification optical path and is amplified by cladding pumping. After amplification, the short-wavelength signal light and the long-wavelength signal light enter the output wavelength division multiplexer and are combined into one signal light output.
[0006] Preferably, the wavelength range of the long-wave signal light is 1550-1565 nm; the wavelength range of the short-wave signal light is 1540-1550 nm.
[0007] Preferably, the shortwave amplification optical path includes a first erbium-ytterbium co-doped optical fiber, a first optical fiber combiner, a first pump light source, and a first isolator; wherein, the first end of the first erbium-ytterbium co-doped optical fiber is located at the input end of the shortwave amplification optical path, the second end of the first erbium-ytterbium co-doped optical fiber is connected to the input end of the first optical fiber combiner, the first pump light source is connected to the pump end of the first optical fiber combiner, the output end of the first optical fiber combiner is connected to the input end of the first isolator, and the output end of the first isolator is located at the output end of the shortwave amplification optical path; And / or, the long-wavelength amplification optical path includes a second erbium-ytterbium co-doped optical fiber, a second optical fiber combiner, a second pump light source, and a second isolator; wherein, the first end of the second erbium-ytterbium co-doped optical fiber is located at the input end of the long-wavelength amplification optical path, the second end of the second erbium-ytterbium co-doped optical fiber is connected to the input end of the second optical fiber combiner, the second pump light source is connected to the pump end of the second optical fiber combiner, the output end of the second optical fiber combiner is connected to the input end of the second isolator, and the output end of the second isolator is located at the output end of the long-wavelength amplification optical path.
[0008] Preferably, the total absorption of the first erbium-ytterbium co-doped fiber to light at a wavelength of 1535 nm is 130-160 dB / m; and / or the total absorption of the second erbium-ytterbium co-doped fiber to light at a wavelength of 1535 nm is 240-270 dB / m.
[0009] Preferably, the first erbium-ytterbium co-doped optical fiber is a multi-layer optical fiber with an inner cladding having an octagonal structure; and / or the second erbium-ytterbium co-doped optical fiber is a multi-layer optical fiber with an inner cladding having an octagonal structure.
[0010] Preferably, the first pump light source is a multimode pump laser with a central wavelength of 915 nm or 940 nm; and / or the second pump light source is a multimode pump laser with a central wavelength of 915 nm or 940 nm.
[0011] Preferably, the wavelength range of the first isolator is 1540-1565 nm, and / or the wavelength range of the second isolator is 1540-1565 nm.
[0012] Preferably, the input wavelength division multiplexer is a coated passive optical device, the transmission wavelength of the transmission port is 1540-1550nm, the reflection wavelength of the reflection port is 1550-1565nm, and the isolation of the two wavelength ports is greater than 40dB; and / or, the output wavelength division multiplexer is a coated passive optical device, the transmission wavelength of the transmission port is 1540-1550nm, and the reflection wavelength of the reflection port is 1550-1565nm.
[0013] Preferably, the system further comprises a first spectrometer, a second spectrometer, a first photodetector, and a second photodetector; wherein:
[0014] The input end of the first optical splitter is connected to the output end of the first optical isolator, the low splitting ratio port of the first optical splitter is connected to the first photodetector, and the high splitting ratio port of the first optical splitter is connected to the transmission end of the output wavelength division multiplexer;
[0015] The second optical splitter input end is connected to the second optical isolator output end, the second optical splitter low splitting ratio port is connected to the second photodetector, and the second optical splitter high splitting ratio port is connected to the output wavelength division multiplexer reflection end.
[0016] Preferably, the first beam splitter and the second beam splitter are 1×2 tapered beam splitters; the first photodetector and the second photodetector are InGaAs photodetectors.
[0017] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the existing technologies:
[0018] The present application adopts a one-stage amplification structure and matches different amplification optical path structures with optical signals of different wavelength ranges through a wavelength division multiplexer, thereby realizing dynamic modulation of the amplification optical path configuration according to the wavelength interval. This improves the problem of uneven signal power gain of different wavelengths in the optical signal when a broadband optical signal is amplified by an optical path amplifier under high-power amplification requirements. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 It is a structural diagram of a fiber optic amplification system provided in an embodiment of the present application.
[0020] Figure 2 This is a diagram of broadband optical signal amplification test results provided in an embodiment of the present application.
[0021] Figure 3 This is a graph showing the test results of a dual-wavelength optical signal amplification provided in an embodiment of the present application.
[0022] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:
[0023] 1 is the input optical isolator; 2 is the input wavelength division multiplexer; 3 is the first erbium-ytterbium co-doped fiber; 4 is the first fiber combiner; 5 is the first pump laser; 6 is the first output optical isolator; 7 is the first optical splitter; 8 is the first photodetector; 9 is the second erbium-ytterbium co-doped fiber; 10 is the second fiber combiner; 11 is the second pump laser; 12 is the second output optical isolator; 13 is the second optical splitter; 14 is the second photodetector; 15 is the output wavelength division multiplexer. DETAILED DESCRIPTION
[0024] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.
[0025] To solve the gain unevenness phenomenon that occurs during the signal amplification process of C-band optical signals, i.e., optical signals with a wavelength range of 1540-1565nm. The present application provides a wavelength-adaptive high-power optical fiber amplification system, comprising two sets of amplification optical paths: a short-wavelength amplification optical path and a long-wavelength amplification optical path. The short-wavelength amplification optical path is used to amplify the signal light with a wavelength of 1540-1550nm by matching the erbium-ytterbium co-doped optical fiber with a total fiber core absorption of 130-160dB / m through cladding pumping. The long-wavelength amplification optical path is used to amplify the signal light with a wavelength of 1550-1565nm by matching the erbium-ytterbium co-doped optical fiber with a total fiber core absorption of 240-270dB / m through cladding pumping. The wavelength of the input signal light is filtered by a wavelength division multiplexer, and the filtered signal light is transmitted to the corresponding amplification optical path by transmission or reflection, thereby realizing wavelength-adaptive optical signal power amplification.
[0026] In order to ensure the flat gain of optical signals in two different wavelength bands, 1540-1550nm and 1550-1565nm, the present application adopts erbium-ytterbium co-doped fiber amplifiers with different total fiber core absorption to amplify the signals.
[0027] The pumping structures used by the short-wavelength amplifying optical path and the long-wavelength amplifying optical path include: a co-directional pumping structure, a counter-directional pumping structure or a bidirectional pumping structure.
[0028] like Figure 1 As shown, an optical fiber amplification system provided by an embodiment of the present application, whose optical path structure includes: 1 input optical isolator, 2 input wavelength division multiplexer, 3 first erbium-ytterbium co-doped optical fiber, 4 first fiber combiner, 5 first pump laser, 6 first output optical isolator, 7 first optical splitter, 8 first photodetector, 9 second erbium-ytterbium co-doped optical fiber, 10 second fiber combiner, 11 second pump laser, 12 second output optical isolator, 13 second optical splitter, 14 second photodetector and 15 output wavelength division multiplexer.
[0029] Flat signal light with a wavelength range of 1540-1565nm and an optical power of 0-20dBm enters the optical path through input optical isolator 1. Input optical isolator 1 is a dual-stage fiber isolator with an isolation greater than 40dB, which is used to reduce interference from return light on the input optical signal. The unidirectional signal light is split into two beams with different wavelength ranges through the two output ports of input wavelength division multiplexer 2.
[0030] Signal light with a wavelength of 1540-1550 nm is transmitted through the transmission port 2a of the input wavelength division multiplexer 2 to the first erbium-ytterbium co-doped fiber 3. A first pump laser 5 is connected to the pump port of the first fiber combiner 4, coupling the 915 / 940 nm pump light into the first erbium-ytterbium co-doped fiber 3 through the first fiber combiner 4. After receiving the pump light energy, the first erbium-ytterbium co-doped fiber 3 amplifies the signal power through stimulated emission. The output of the first fiber combiner 4 is connected to the first optical isolator 6. The non-reciprocity of the first optical isolator 6 effectively prevents backscatter from affecting the first erbium-ytterbium co-doped fiber, ensuring signal amplification quality. The output of the first optical isolator 6 is connected to the input of the first optical splitter 7. The low-splitting ratio port of the first optical splitter 7 is connected to the first photodetector 8. The high-splitting ratio port of the first optical splitter 7 is used for the output of the optical path and is connected to the transmission port 15a of the output wavelength division multiplexer 15.
[0031] Signal light with a wavelength of 1550-1565 nm is transmitted through the reflection port 2b of the input wavelength division multiplexer 2 to the second erbium-ytterbium co-doped fiber 9. A second pump laser 11 is connected to the pump end of the second fiber combiner 10, coupling the 915 / 940 nm pump light into the second erbium-ytterbium co-doped fiber 9 through the second fiber combiner 10. After receiving the energy from the pump light, the second erbium-ytterbium co-doped fiber 9 amplifies the signal power through stimulated emission. The output end of the second fiber combiner 10 is connected to the second optical isolator 12. The non-reciprocity of the second optical isolator 12 effectively prevents backscatter from affecting the second erbium-ytterbium co-doped fiber 9, ensuring signal amplification quality. The output end of the second optical isolator 12 is connected to the input end of the second optical splitter 13, the low splitting ratio port of the second optical splitter 13 is connected to the second photodetector 14, and the high splitting ratio port of the second optical splitter 13 is used for the output of the optical path and is connected to the reflection end 15b of the output wavelength division multiplexer 15.
[0032] Signal lights with wavelengths in different ranges are combined together through the transmission end 15a and the reflection end 15b by the output wavelength division multiplexer, and amplified signal lights with different wavelengths and flat power are output.
[0033] The optical fiber amplification system is constructed using a pure optical fiber structure, wherein the components are connected by optical fiber fusion splicing.
[0034] The input optical isolator 1 utilizes non-reciprocity to isolate the return light from noise interference on the signal light, achieving a minimum isolation of 40dB within the wavelength range of 1540nm-1565nm. The optical isolator's wavelength range is limited to ensure that optical signals in the 1540-1565nm range enter the back-end optical path intact for signal amplification while effectively isolating the return light from affecting the input optical signal, thereby improving signal amplification quality.
[0035] The input wavelength division multiplexer 2 is a coated passive optical device. Its transmission port 2a transmits a wavelength of 1540-1550 nm, while its reflection port 2b reflects a wavelength of 1550-1565 nm. The isolation between the two wavelength ports is greater than 40 dB. This splits the input light in the 1540-1565 nm band into one optical signal in the 1540-1550 nm band, which is emitted from the transmission port 2a, and one optical signal in the 1550-1565 nm band, which is emitted from the reflection port 2b. To ensure the overall amplification performance of the optical amplifier, the first erbium-ytterbium co-doped fiber 3 is a multi-clad fiber using a low-refractive index coating. The innermost cladding within the coating has an octagonal structure, which enhances the ability of pump light to pass through the fiber core. The cladding absorption coefficient for 915 nm wavelength light is 2.5±0.5 dB / m, and the core absorption coefficient is 35-65 dB / m. To ensure the gain flatness of the two optical signals, the total absorption of the optical fiber core for 1535nm wavelength light is 130-160dB / m.
[0036] The first fiber combiner 4 and the second fiber combiner 10 are tapered fiber combiners with a (1+1)×1 structure, whose output ends transmit amplified signal light and whose pump ends transmit pump light.
[0037] The first and second pump light sources 5 and 11 are multimode pump lasers with a central wavelength of 915 nm or 940 nm, and their output pigtails are 105 / 125 step-index multimode fibers with a maximum output power of 10 W. The central wavelength of the pump light source depends on the specific laser and its working medium. Multimode pump lasers with a central wavelength of 915 nm or 940 nm are particularly suitable for the erbium-ytterbium co-doped fiber amplifiers described in this application.
[0038] The first and second output optical isolators 6 and 12 are used to isolate the backscattered light from interfering with the preceding erbium-ytterbium co-doped fiber. They offer a minimum isolation of 40 dB in the 1540-1565 nm wavelength range and a power handling capacity of 3 W. This ensures that optical signals in the 1540-1565 nm range have a high optical signal-to-noise ratio after passing through the amplified optical path. The first and second optical splitters 7 and 13 are 1×2 tapered splitters with a splitting ratio of 1:99. Here, an optical signal with a power ratio of 1 is input to a photodetector for optical signal detection, and an optical signal with a power ratio of 99 is output.
[0039] The first photodetector 8 and the second photodetector 14 are InGaAs photodetectors, which convert the detected optical signal into an electrical signal and obtain the output power of the current optical path according to the detected voltage signal;
[0040] In this embodiment, the optical splitter and the photodetector are used to detect the output power of the two optical paths to verify the flatness of the output power of signal light in different bands, and are optional components.
[0041] To ensure the overall amplification performance of the optical amplifier, the second erbium-ytterbium co-doped fiber 9 is a multi-clad fiber with a low-refractive index coating. The innermost cladding within the coating has an octagonal structure. The cladding absorption coefficient for 915nm wavelength light is 2.5±0.5dB / m, and the core absorption coefficient is 35-65dB / m. To ensure flat gain of the two optical signals, the total absorption of the fiber core for 1535nm wavelength light is 240-270dB / m.
[0042] The output wavelength division multiplexer 15 is a coated passive optical device. The transmission wavelength of its transmission port 15a is 1540-1550nm, the reflection wavelength of its reflection port 15b is 1550-1565nm, and the power handling capacity is 5W. Thus, the amplified optical signals in the 1540-1550nm band and the amplified optical signals in the 1550-1565nm band are combined into a single optical signal in the 1540-1565nm band for output.
[0043] Figure 2 This is a comparison chart of the experimental results of amplifying broadband signal light.
[0044] In the comparative test, the optical power of the input signal light is 15dBm, and the signal light covers 1540nm-1565nm at a frequency interval of 200GHz.
[0045] The signal light is amplified by the optical fiber amplification system proposed in this application and the conventional optical fiber amplification system respectively. The power after amplification is as follows: Figure 2 As shown in:
[0046] The solid line portion in the figure represents the power distribution after amplification by a conventional optical fiber amplification system. It can be seen that the flatness of the output signal at each wavelength is 4.2dB.
[0047] The dotted part in the figure is the power distribution after amplification by the optical fiber amplification system proposed in this application. It can be seen that when branch amplification is adopted, the flatness of the signal output at each wavelength is 1.98dB.
[0048] By comparison, it can be seen that the optical fiber amplification system of the present application can effectively improve the flatness of broadband signal light after amplification under high power amplification requirements.
[0049] Figure 3 This is a comparison chart of the experimental results of amplifying dual-wavelength signal light.
[0050] In the comparative test, the optical power of the input signal light is 15 dBm, and the wavelengths of the signal light are dual wavelengths of 1545 nm and 1563 nm.
[0051] The signal light is amplified by the optical fiber amplification system proposed in this application and the conventional optical fiber amplification system respectively. The power after amplification is as follows: Figure 3 As shown in:
[0052] The solid line portion in the figure represents the power distribution after amplification by a conventional optical fiber amplification system. It can be seen that the flatness of the output signal at each wavelength is 0.8dB.
[0053] The dotted part in the figure is the power distribution after amplification by the optical fiber amplification system proposed in this application. It can be seen that when branch amplification is adopted, the flatness of the signal output at each wavelength is 0.2dB.
[0054] By comparison, it can be seen that the optical fiber amplification system of the present application can effectively improve the flatness of the dual-wavelength signal light after amplification under high-power amplification requirements.
[0055] Figure 2 and Figure 3 Some experiments have shown that, compared with existing conventional fiber optic amplification systems, the fiber optic amplification system of the present application can effectively improve the problem of uneven gain of broadband signal light or signal light with a large wavelength interval during the fiber optic amplification process.
[0056] It should be understood that expressions such as "include" and "may include" used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "include" and / or "have" may be interpreted as indicating specific characteristics, numbers, operations, constituent elements, components, or combinations thereof, but may not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.
[0057] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Among them, "fixed connection" means that the two are connected to each other and the relative position relationship after the connection remains unchanged. "Rotational connection" means that the two are connected to each other and can rotate relative to each other after the connection. "Sliding connection" means that the two are connected to each other and can slide relative to each other after the connection. The directional terms mentioned in the embodiments of the present application, such as "top", "bottom", "inside", "outside", "left", "right", etc., are only reference to the directions of the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of the present application, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.
[0058] In addition, in the embodiments of the present application, the mathematical concepts mentioned include symmetry, equality, parallelism, and perpendicularity. These limitations are all for the current state of the art, rather than being absolutely strict definitions in a mathematical sense. A small amount of deviation is allowed, and it is possible to be approximately symmetric, approximately equal, approximately parallel, or approximately perpendicular. For example, A and B are parallel, which means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. A and B are perpendicular, which means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.
[0059] The term "and / or" in this application describes an association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, or B exists alone. The symbol " / " in this document indicates that the associated objects are in an "or" relationship, for example, A / B means A or B.
[0060] It will be understood that the various numerical numbers involved in the embodiments of the present application are merely distinctions for the convenience of description and are not intended to limit the scope of the embodiments of the present application.
[0061] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.
Claims
1. A wavelength adaptive optical fiber amplification system, characterized in that: The optical fiber amplification system includes an input wavelength division multiplexer, a short-wavelength amplification optical path, a long-wavelength amplification optical path, and an output wavelength division multiplexer. After the signal light enters the input wavelength division multiplexer, it is divided into long-wavelength signal light and short-wavelength signal light. The long-wavelength signal light enters the long-wavelength amplification optical path and is amplified by cladding pumping. The short-wavelength signal light enters the short-wavelength amplification optical path and is amplified by cladding pumping. After amplification, the short-wavelength signal light and the long-wavelength signal light enter the output wavelength division multiplexer and are combined into one signal light output.
2. The optical fiber amplification system according to claim 1, wherein: The wavelength range of the long-wave signal light is 1550-1565nm; the wavelength range of the short-wave signal light is 1540-1550nm.
3. The optical fiber amplification system according to claim 1, wherein: The short-wavelength amplification optical path includes a first erbium-ytterbium co-doped optical fiber, a first optical fiber combiner, a first pump light source and a first isolator; wherein, the first end of the first erbium-ytterbium co-doped optical fiber is located at the input end of the short-wavelength amplification optical path, the second end of the first erbium-ytterbium co-doped optical fiber is connected to the input end of the first optical fiber combiner, the first pump light source is connected to the pump end of the first optical fiber combiner, the output end of the first optical fiber combiner is connected to the input end of the first isolator, and the output end of the first isolator is located at the output end of the short-wavelength amplification optical path; and / or, the long-wavelength amplification optical path includes a second erbium-ytterbium co-doped optical fiber, a second optical fiber combiner, a second pump light source and a second isolator; wherein, the first end of the second erbium-ytterbium co-doped optical fiber is located at the input end of the long-wavelength amplification optical path, the second end of the second erbium-ytterbium co-doped optical fiber is connected to the input end of the second optical fiber combiner, the second pump light source is connected to the pump end of the second optical fiber combiner, the output end of the second optical fiber combiner is connected to the input end of the second isolator, and the output end of the second isolator is located at the output end of the long-wavelength amplification optical path.
4. The optical fiber amplification system according to claim 3, wherein: The total absorption of the first erbium-ytterbium co-doped fiber to light of 1535 nm wavelength in the fiber core is 130-160 dB / m; and / or the total absorption of the second erbium-ytterbium co-doped fiber to light of 1535 nm wavelength in the fiber core is 240-270 dB / m.
5. The optical fiber amplification system according to claim 4, wherein: The first erbium-ytterbium co-doped optical fiber is a multi-layer optical fiber with an inner cladding having an octagonal structure; and / or the second erbium-ytterbium co-doped optical fiber is a multi-layer optical fiber with an inner cladding having an octagonal structure.
6. The optical fiber amplification system according to claim 3, wherein: The first pump light source is a multimode pump laser with a central wavelength of 915 nm or 940 nm; and / or the second pump light source is a multimode pump laser with a central wavelength of 915 nm or 940 nm.
7. The optical fiber amplification system according to claim 3, wherein: The wavelength range of the first isolator is 1540-1565 nm, and / or the wavelength range of the second isolator is 1540-1565 nm.
8. The optical fiber amplification system according to claim 1, wherein: The input wavelength division multiplexer is a coated passive optical device, the transmission wavelength of the transmission port is 1540-1550nm, the reflection wavelength of the reflection port is 1550-1565nm, and the isolation between the two wavelength ports is greater than 40dB; and / or, the output wavelength division multiplexer is a coated passive optical device, the transmission wavelength of the transmission port is 1540-1550nm, and the reflection wavelength of the reflection port is 1550-1565nm.
9. The optical fiber amplification system according to claim 1, wherein: The system further comprises a first optical splitter, a second optical splitter, a first photodetector and a second photodetector; wherein: The input end of the first optical splitter is connected to the output end of the first optical isolator, the low splitting ratio port of the first optical splitter is connected to the first photodetector, and the high splitting ratio port of the first optical splitter is connected to the transmission end of the output wavelength division multiplexer; The second optical splitter input end is connected to the second optical isolator output end, the second optical splitter low splitting ratio port is connected to the second photodetector, and the second optical splitter high splitting ratio port is connected to the output wavelength division multiplexer reflection end.
10. The optical fiber amplification system according to claim 9, wherein: The first optical splitter and the second optical splitter are 1 2 is a tapered spectrometer; the first photodetector and the second photodetector are InGaAs photodetectors.