Optical fiber amplifier and optical fiber laser
Through the combination of two-stage amplification structure and components such as erbium-ytterbium co-doped optical fiber, the line width and noise problems of the existing 1.6μm band fiber laser are solved, and a high-power, low-noise 1.6μm band single-frequency laser output is achieved, satisfying the coherence Application requirements for optical communication and atmospheric environment detection.
Patent Information
- Application Number
- CN202421175256.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-27
- Publication Date
- 2025-01-07
- Estimated Expiration
- 2034-05-27
AI Technical Summary
The existing 1.6μm band high-power single-frequency fiber lasers have wide line widths and low light signal-to-noise ratios, and amplified spontaneous emission and stimulated Brillouin scattering are prone to occur under high output power, resulting in deterioration of output characteristics, limiting the Its application in fields such as coherent optical communication and atmospheric environment detection.
Using a two-stage amplification structure, the 1.5μm band pump source generates gain in the gain optical fiber, which increases the output power of the 1.6μm band seed light from 10mW to 1.5W, and is used by the combination of the first and second amplification components. Combining components such as erbium-ytterbium co-doped optical fiber and wavelength division multiplexer, a single frequency laser output with high power and low noise is achieved.
It realizes a 1.6μm band single-frequency laser output with high power, low noise and narrow line width, meeting the needs of coherent optical communication, atmospheric environment detection and remote sensing, and improving the optical signal-to-noise ratio and beam quality.
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Figure CN222320802U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of optical fiber lasers, in particular to an optical fiber amplifier and an optical fiber laser. Background Art
[0002] 1.5μm-1.6μm band high power erbium-doped (Er 3+ ) Single-frequency fiber laser (SFFL) has attracted much attention due to its advantages such as high power, narrow linewidth, low noise and good beam quality. These advantages make it have broad application prospects in coherent lidar, nonlinear frequency conversion, optical communication and spectroscopy. Although 1.6μm (L-band) single-frequency lasers are very attractive for applications such as high-resolution molecular spectroscopy, they particularly require narrow linewidth and low noise characteristics of the laser source to achieve the desired resolution. However, due to the Er 3+ Due to the small emission cross section near the 1.6μm band in doped fibers, most reported studies are limited to laser operation in the C-band (1535nm-1565nm). In addition, 1.6μm band laser sources can also be used as in-band pump sources for thulium-doped fiber lasers or thulium-holmium co-doped fiber lasers to achieve efficient laser output.
[0003] Although some solid-state lasers based on Er-doped ions can operate in the 1.6 μm band and produce tens of watts of single-frequency output, their high maintenance requirements, low conversion efficiency, and high environmental sensitivity limit their widespread application. 3+ High-power fiber lasers with fiber master oscillator power-amplifiers (MOPAs) can also be operated at 1.6 μm through delicate manipulation. The MOPA scheme consists of a seed laser and one or more fiber amplifiers that provide power scaling while preserving the inherent single-frequency characteristics of the seed.
[0004] However, these lasers of the currently reported MOPA schemes have relatively wide linewidths and low optical signal-to-noise ratios (OSNR) < 50 dB, which will hinder their further application. So far, there are few reports of high-power, low-noise, strictly single-frequency fiber MOPAs above 1600 nm. On the one hand, longer wavelength operation with a smaller gain coefficient near 1.6 μm usually results in amplified spontaneous emission (ASE) in the 1.0 μm / 1.5 μm band or Yb 3+ / Er 3+ions, which will limit the signal laser power and damage the pre-amplifier. Managing ASE in two bands in a real fiber MOPA system remains a challenge. On the other hand, as the output power increases, the output characteristics of MOPA (such as laser linewidth, noise characteristics, beam quality, etc.) will inevitably deteriorate due to the appearance of ASE, stimulated Brillouin scattering (SBS) and thermal effects. Utility Model Content
[0005] The utility model provides a fiber amplifier and a fiber laser, which improve the power of the seed light in the 1.6μm band by two-stage amplification, make full use of the gain generated by the pump source in the 1.5μm band in the gain fiber, improve the output power, and finally increase the seed light in the 1.6μm band from 10mW to 1.5W. This high-power 1.6μm band single-frequency laser fully meets the application requirements of coherent optical communication, atmospheric environment detection and remote sensing.
[0006] According to a first aspect of the utility model, there is provided a fiber amplifier, comprising: at least one first amplification component, at least one second amplification component and a pump fiber laser;
[0007] The first end of the first amplifying component receives the seed light in the 1.6 μm band, and the output end of the first amplifying component is connected to the first end of the second amplifying component; the output end of the pump fiber laser is respectively connected to the pump end of the first amplifying component and the pump end of the second amplifying component; the pump fiber laser emits the first pump light in the 1.5 μm band;
[0008] The seed light is amplified once by the first amplifying component and twice by the second amplifying component, and then emitted from the third end of the second amplifying component.
[0009] Optionally, the first amplification component includes: a first circulator, a first erbium-ytterbium co-doped optical fiber, a first wavelength division multiplexer and a first optical fiber grating;
[0010] The first end of the first circulator serves as a receiving end of the first amplifying component to receive the seed light; the second end of the first circulator is connected to the first end of the first erbium-ytterbium co-doped fiber, the second end of the first erbium-ytterbium co-doped fiber is connected to the first end of the first wavelength division multiplexer, the second end of the first wavelength division multiplexer is connected to the first fiber grating, and the pump input end of the first wavelength division multiplexer is connected to the output end of the pump fiber laser;
[0011] The third end of the first circulator serves as the output end of the first amplifying component and is connected to the first end of the second amplifying component.
[0012] Optionally, the second amplification component includes: a second circulator, a second wavelength division multiplexer, a second erbium-ytterbium co-doped optical fiber, a third wavelength division multiplexer and a coupler;
[0013] The first end of the second circulator is connected to the output end of the first amplifying component, and the second end of the second circulator is connected to the first end of the second wavelength division multiplexer;
[0014] The second end of the second wavelength division multiplexer is connected to the first end of the second erbium-ytterbium co-doped optical fiber, the second end of the second erbium-ytterbium co-doped optical fiber is connected to the first end of the third wavelength division multiplexer, the second end of the third wavelength division multiplexer is connected to the input end of the coupler, the pump input end of the third wavelength division multiplexer is connected to the output end of the pump fiber laser; the first output end of the coupler is connected to the second output end of the coupler;
[0015] The third end of the second circulator serves as the output end of the second amplifying component.
[0016] Optionally, the pump fiber laser comprises: a light source assembly, a pump combiner, a second fiber Bragg grating, a third erbium-ytterbium co-doped fiber, a third fiber Bragg grating and a third circulator, wherein the second fiber Bragg grating, the third erbium-ytterbium co-doped fiber and the third fiber Bragg grating are sequentially connected to form a linear cavity;
[0017] The light source assembly emits a second pump light in the 0.9 μm band, the second pump light is input into the linear cavity from the input end of the pump combiner, the linear cavity outputs the first pump light to the first end of the third circulator, and outputs from the second end of the third circulator.
[0018] Optionally, the light source assembly includes at least one 20W laser diode with a wavelength of 940nm.
[0019] Optionally, the pump fiber laser further comprises a pump stripper;
[0020] The pump stripper is located between the second fiber grating and the third fiber grating.
[0021] Optionally, the reflectivity of the second fiber grating is smaller than the reflectivity of the third fiber grating, the first end of the third fiber grating is located in the linear cavity, and the end face of the second end of the third fiber grating is inclined at an angle of 8°.
[0022] Optionally, the first end of the first optical fiber grating is connected to the second end of the first wavelength division multiplexer, and the end face of the second end of the first optical fiber grating is inclined at an angle of 8°.
[0023] Optionally, the first erbium-ytterbium co-doped optical fiber is a double-clad optical fiber.
[0024] According to a second aspect of the utility model, a fiber laser is provided, comprising a seed source and the fiber amplifier described in any one of the first aspects, wherein the seed source emits a single-frequency laser of 1620 nm.
[0025] The utility model discloses a fiber amplifier and a fiber laser, comprising: at least one first amplifying component, at least a first second amplifying component and a pump fiber laser; the first end of the first amplifying component receives a seed light in the 1.6μm band, and the output end of the first amplifying component is connected to the first end of the second amplifying component; the output end of the pump fiber laser is respectively connected to the pump end of the first amplifying component and the pump end of the second amplifying component; the pump fiber laser emits a first pump light in the 1.5μm band; the seed light is amplified by the first amplifying component and the second amplifying component, and then emitted from the third end of the second amplifying component. The fiber amplifier and fiber laser provided by the utility model increase the power of the seed light in the 1.6μm band by two-stage amplification, fully utilize the gain generated in the gain fiber of the pump source 1.5μm band, increase the output power, and finally increase the seed light in the 1.6μm band from 10mW to 1.5W. This high-power 1.6μm band single-frequency laser fully meets the application requirements of coherent optical communication, atmospheric environment detection and remote sensing.
[0026] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present utility model, nor are they intended to limit the scope of the present utility model. Other features of the present utility model will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0028] Figure 1 It is a structural schematic diagram of a fiber optic amplifier provided by an embodiment of the utility model;
[0029] Figure 2 This is a schematic diagram of another optical fiber amplifier structure provided by an embodiment of the utility model;
[0030] Figure 3 It is a structural schematic diagram of another optical fiber amplifier provided by an embodiment of the utility model;
[0031] Figure 4It is a schematic diagram of the structure of a pump fiber laser in a fiber amplifier provided by an embodiment of the utility model;
[0032] Figure 5 This is an output spectrum diagram of an optical fiber amplifier provided by an embodiment of the utility model. DETAILED DESCRIPTION
[0033] In order to enable those skilled in the art to better understand the solution of the utility model, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is only a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the utility model.
[0034] It should be noted that the terms "first", "second", etc. in the specification and claims of the utility model and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the utility model described here can be implemented in an order other than those illustrated or described here. 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 clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.
[0035] Figure 1 is a schematic diagram of the structure of an optical fiber amplifier provided by an embodiment of the utility model, with reference to Figure 1 The embodiment of the utility model provides a fiber amplifier, comprising: at least one first amplifying component 1, at least one second amplifying component 2 and a pump fiber laser 3; the first end Input of the first amplifying component 1 receives a seed light in the 1.6 μm band, and the output end of the first amplifying component 1 is connected to the first end of the second amplifying component 2; the output end of the pump fiber laser 3 is respectively connected to the pump end of the first amplifying component 1 and the pump end of the second amplifying component 2; the pump fiber laser 3 emits a first pump light in the 1.5 μm band; the seed light is amplified by the first amplifying component 1 and the second amplifying component 2, and then emitted from the third end Output of the second amplifying component 2.
[0036] Specifically, the seed light of 1.6 μm band received by the first amplifying component 1 is transmitted to the inside of the second amplifying component 2 after being amplified by the first amplifying component 1, and the seed light is amplified inside the second amplifying component 2 and then output by the second amplifying component 2. The detailed internal structures of the first amplifying component 1 and the second amplifying component 2 will be described below, and will not be described in detail here for the time being. Figure 1 It is shown that the first amplifying component 1 and the second amplifying component 2 are both connected to the same pump fiber laser 3. In other embodiments, two pump fiber lasers 3 can be respectively connected to the first amplifying component 1 and the second amplifying component 2, or more pump fiber lasers 3 can be provided as needed. The specific implementation can be designed according to actual conditions.
[0037] In the two-stage amplifier structure, except for the gain fiber, the pigtails of all other devices are PM1550 polarization-maintaining fibers. The polarization fidelity performance and insertion loss of each fusion point are optimized respectively. The measured fusion loss between the gain fiber and the PM1550 fiber is about 0.35dB, and the fusion loss between PM1550nm fibers is about 0.2dB.
[0038] The optical fiber amplifier provided by the embodiment of the utility model performs power boosting on the seed light in the 1.6μm band through two-stage amplification, fully utilizes the gain generated in the gain fiber in the 1.5μm band of the pump source, improves the output power, and finally increases the seed light in the 1.6μm band from 10mW to 1.5W. This high-power 1.6μm band single-frequency laser fully meets the application requirements of coherent optical communication, atmospheric environment detection and remote sensing.
[0039] Figure 2 is a schematic diagram of the structure of another optical fiber amplifier provided by an embodiment of the utility model, referring to Figure 2 Optionally, the first amplifying component 1 includes: a first circulator 11, a first erbium-ytterbium co-doped fiber 12, a first wavelength division multiplexer 13 and a first fiber grating 14; the first end a of the first circulator 11 serves as a receiving end of the first amplifying component 1 to receive the seed light; the second end b of the first circulator 11 is connected to the first end of the first erbium-ytterbium co-doped fiber 12, the second end of the first erbium-ytterbium co-doped fiber 12 is connected to the first end of the first wavelength division multiplexer 13, the second end of the first wavelength division multiplexer 13 is connected to the first fiber grating 14, and the pump input end of the first wavelength division multiplexer 13 is connected to the output end of the pump fiber laser 3; the third end c of the first circulator 11 serves as the output end of the first amplifying component 1 and is connected to the first end of the second amplifying component 2.
[0040] Specifically, the first circulator 11 has three ports, namely ports a, b and c, and its main function is to ensure that the pump light can be transmitted in sequence and not in reverse. The first wavelength division multiplexer 13 is a device that can simultaneously transmit multiple optical signals of different wavelengths on the same optical fiber, and can combine light of different wavelengths into the same optical fiber, so as to transmit the first pump light of 1.5μm band to the first erbium-ytterbium co-doped optical fiber 12. The seed light is gain-amplified in the first erbium-ytterbium co-doped optical fiber 12 and then transmitted to the first fiber grating 14. The central wavelength of the first fiber grating 14 is consistent with the wavelength of the seed light, and the bandwidth is 0.2nm, so as to reflect the laser with the same wavelength as the seed light and transmit the light of other bands to achieve the amplification of the seed light. The first fiber grating 14 re-reflects the amplified and filtered seed light into the first erbium-ytterbium co-doped optical fiber 12 for secondary amplification. The pump end of the first wavelength division multiplexer 13 is connected to the output end of the pump fiber laser 3 , and the seed light after two times of gain amplification is transmitted from the third end c of the first circulator 11 to the second amplifying component 2 .
[0041] Figure 3 This is another schematic diagram of the structure of an optical fiber amplifier provided by the embodiment of the utility model, referring to Figure 3 Optionally, the second amplifying component 2 includes: a second circulator 21, a second wavelength division multiplexer 22, a second erbium-ytterbium co-doped optical fiber 23, a third wavelength division multiplexer 24 and a coupler 25; the first end x of the second circulator 21 is connected to the output end of the first amplifying component 1, and the second end y of the second circulator 21 is connected to the first end of the second wavelength division multiplexer 22; the second end of the second wavelength division multiplexer 22 is connected to the first end of the second erbium-ytterbium co-doped optical fiber 23, the second end of the second erbium-ytterbium co-doped optical fiber 23 is connected to the first end of the third wavelength division multiplexer 24, the second end of the third wavelength division multiplexer 24 is connected to the input end of the coupler 25, and the pump input end of the third wavelength division multiplexer 24 is connected to the output end of the pump fiber laser 3; the first output end of the coupler 25 is connected to the second output end of the coupler 25; the third end z of the second circulator 21 serves as the output end of the second amplifying component 2.
[0042] Specifically, the output end of the first amplifying component 1 is transmitted to the first end x of the second circulator 21, and then transmitted to the coupler 25 after gain amplification through the second erbium-ytterbium co-doped optical fiber 23. The first output end of the coupler 25 is connected to the second output end and fused together to form a broadband reflector, and the seed light is re-reflected into the second erbium-ytterbium co-doped optical fiber 23 for reverse secondary amplification, wherein the coupling ratio of the coupler 25 can be 50:50; the seed light after bidirectional amplification is output to the outside from the third end z of the second circulator 21, and the 1.5μm band ASE (spontaneous emission is a noise source generated in the process of optical signal transmission, which is the random emission of light caused by impurities or impurities in the optical fiber) generated by the amplifier and the remaining pump light are leaked out from the pump end of the second wavelength division multiplexer 22, thereby obtaining a pure signal light output with a high signal-to-noise ratio.
[0043] Figure 4 This is a schematic diagram of the structure of a pump fiber laser in a fiber amplifier provided by an embodiment of the utility model, with reference to Figure 4 Optionally, the pump fiber laser 3 includes: a light source assembly 31, a pump combiner 32, a second fiber grating 33, a third erbium ytterbium co-doped fiber 34, a third fiber grating 35 and a third circulator 36, the second fiber grating 33, the third erbium ytterbium co-doped fiber 34 and the third fiber grating 35 are sequentially connected to form a linear cavity; the light source assembly 31 emits a second pump light in the 0.9 μm band, the second pump light is input into the linear cavity from the input end of the pump combiner 32, the linear cavity outputs the first pump light to the first end d of the third circulator 36, and is output from the second end f of the third circulator 36.
[0044] Specifically, the pump fiber laser 3 includes a light source assembly 31, a pump combiner 32, a second fiber Bragg grating 33, a third erbium ytterbium co-doped fiber 34, a third fiber Bragg grating 35 and a third circulator 36. The second fiber Bragg grating 33, the third erbium ytterbium co-doped fiber 34 and the third fiber Bragg grating 35 are sequentially connected to form a linear cavity. The light source assembly emits a second pump light in the 0.9 μm band, and the second pump light is input into the linear cavity from the input end of the pump combiner 32. The linear cavity outputs a first pump light in the 1.5 μm band to the first end d of the third circulator 36, and is output from the second end f of the third circulator 36.
[0045] The function of the pump combiner 32 is to combine at least one pump light into one optical fiber for output, so as to increase the pump power; the pump fiber laser is composed of a light source component 31, a pump combiner 32, a second fiber grating 33, a third erbium-ytterbium co-doped fiber 34, a third fiber grating 35 and a third circulator 36; the formed linear cavity absorbs and converts the second pump light of 0.9μm band emitted by the light source component 31 to form a first pump light of 1.5μm band and transmits it to the second port e of the third circulator 36, and outputs it from the first end d of the third circulator 36. The ASE of 1.5um band generated by the amplifier will be output to the outside through the third end z of the third circulator 36, thereby ensuring the safe operation of the pump fiber laser.
[0046] Optional, continue to refer to Figure 4 The light source assembly 31 includes at least one 20W laser diode with a wavelength of 940nm.
[0047] Optional, continue to refer to Figure 4 The pump fiber laser 3 further includes a pump stripper 37 ; the pump stripper 37 is located between the second fiber grating 33 and the third fiber grating 35 .
[0048] The pump stripper 37 is mainly used to remove the remaining pump light after energy exchange to ensure the stable operation of the pump fiber laser.
[0049] Optionally, the reflectivity of the second fiber grating 33 is smaller than that of the third fiber grating 35 , the first end of the third fiber grating 35 is located in the linear cavity, and the end face of the second end of the third fiber grating 35 is inclined at an angle of 8°.
[0050] Specifically, the end face of the second end of the third fiber grating 35 is cut at an angle of 8° to prevent reflection.
[0051] Optional, reference Figure 2 The first end of the first fiber grating 14 is connected to the second end of the first wavelength division multiplexer 13, and the end face of the second end of the first fiber grating 14 is inclined at an angle of 8°.
[0052] Specifically, the end face of the second end of the first fiber grating 14 is cut at an angle of 8° to prevent reflection.
[0053] Optional, reference Figure 2 The first erbium-ytterbium co-doped optical fiber 12 is a double-clad optical fiber.
[0054] Based on the same concept, an embodiment of the utility model further discloses a fiber laser, comprising a seed source and the fiber amplifier described in any of the above utility model embodiments, wherein the seed source emits a single-frequency laser of 1620 nm.
[0055] Specifically, the fiber laser provided in the embodiment of the utility model can achieve the same technical effect as any of the above embodiments, which will not be described in detail here.
[0056] The principle of the optical fiber amplifier provided by the embodiment of the utility model is as follows:
[0057] A 1620nm single-frequency narrow-linewidth laser is used as a seed source, with an output power of about 10mW and a linewidth of 800Hz. This signal light is input into the first erbium-ytterbium co-doped fiber through the first circulator. The amplifier is provided with gain by the polarization-maintaining double-clad erbium-ytterbium co-doped fiber. A 1532nm pump fiber laser is used as a pump source and injected into the gain fiber (i.e., the first erbium-ytterbium co-doped fiber) through the first wavelength division multiplexer for core pumping. The amplified 1620nm single-frequency linearly polarized signal light is reflected by the first fiber grating into the gain fiber for secondary amplification. At the same time, the first fiber grating with a bandwidth of only 0.2nm can also filter out the spontaneous emission (ASE) of the 1.6μm band in the forward transmission. The ASE of the 1.5μm band in the forward transmission is input from the pump end of the first wavelength division multiplexer to the d port of the third circulator in the pump source part, and finally leaks out from the f port, so that only the pure signal light will be amplified again.
[0058] The amplified signal light is input into the second-stage erbium-ytterbium co-doped fiber again by the first circulator. The amplifier is still provided with gain by the polarization-maintaining double-clad erbium-ytterbium co-doped fiber. The 1532nm pump fiber laser is used as the pump source and injected into the gain fiber through the wavelength division multiplexer for core pumping. The amplified 1620nm single-frequency linearly polarized signal light is reflected by the broadband reflector composed of a 50:50 coupler into the gain fiber for secondary amplification. A wavelength division multiplexer (i.e., the second wavelength division multiplexer and the third wavelength division multiplexer) is connected to each end of the gain fiber to leak the ASE of the 1.5μm band transmitted in the forward and reverse directions from the pump end of the second wavelength division multiplexer, thereby ensuring that the output 1620nm single-frequency linearly polarized signal light still maintains a high signal-to-noise ratio under the condition of high output power. When the 1532nm pump power is 7W, the 1620nm signal light output from the 3 ports of the CIR can reach 1.5W, with an optical signal-to-noise ratio of 63dB and an optical-to-optical conversion efficiency of 21.4%.
[0059] Figure 5 This is an output spectrum diagram of a fiber amplifier provided by an embodiment of the utility model. The output spectrum of the 1620nm single-frequency linearly polarized signal light is as follows: Figure 5 shown.
[0060] The optical fiber amplifier provided by the embodiment of the utility model has the following advantages:
[0061] 1. Using 1532nm fiber laser core pumping, high optical efficiency;
[0062] 2. Reference Figure 2 , suitable for 1.6μm band signal light amplification, high output power;
[0063] 3. Simple and flexible structure, easy to make;
[0064] 4. Good output stability, small size, and easy to carry.
[0065] The above specific implementations do not constitute a limitation on the protection scope of the present utility model. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present utility model shall be included in the protection scope of the present utility model.
Claims
1. An optical fiber amplifier, characterized in that: include: at least one first amplification component, at least one second amplification component, and a pump fiber laser; The first end of the first amplifying component receives the seed light in the 1.6 μm band, and the output end of the first amplifying component is connected to the first end of the second amplifying component; the output end of the pump fiber laser is respectively connected to the pump end of the first amplifying component and the pump end of the second amplifying component; The pump fiber laser emits a first pump light in the 1.5 μm band; The seed light is amplified once by the first amplifying component and twice by the second amplifying component, and then emitted from the third end of the second amplifying component.
2. The optical fiber amplifier according to claim 1, characterized in that: The first amplification component includes: a first circulator, a first erbium-ytterbium co-doped optical fiber, a first wavelength division multiplexer and a first optical fiber grating; The first end of the first circulator serves as a receiving end of the first amplifying component to receive the seed light; the second end of the first circulator is connected to the first end of the first erbium-ytterbium co-doped fiber, the second end of the first erbium-ytterbium co-doped fiber is connected to the first end of the first wavelength division multiplexer, the second end of the first wavelength division multiplexer is connected to the first fiber grating, and the pump input end of the first wavelength division multiplexer is connected to the output end of the pump fiber laser; The third end of the first circulator serves as the output end of the first amplifying component and is connected to the first end of the second amplifying component.
3. The optical fiber amplifier according to claim 1, characterized in that: The second amplification component includes: a second circulator, a second wavelength division multiplexer, a second erbium-ytterbium co-doped optical fiber, a third wavelength division multiplexer and a coupler; The first end of the second circulator is connected to the output end of the first amplifying component, and the second end of the second circulator is connected to the first end of the second wavelength division multiplexer; The second end of the second wavelength division multiplexer is connected to the first end of the second erbium-ytterbium co-doped optical fiber, the second end of the second erbium-ytterbium co-doped optical fiber is connected to the first end of the third wavelength division multiplexer, the second end of the third wavelength division multiplexer is connected to the input end of the coupler, the pump input end of the third wavelength division multiplexer is connected to the output end of the pump fiber laser; the first output end of the coupler is connected to the second output end of the coupler; The third end of the second circulator serves as the output end of the second amplifying component.
4. The optical fiber amplifier according to claim 1, characterized in that: The pump fiber laser comprises: a light source assembly, a pump combiner, a second fiber Bragg grating, a third erbium-ytterbium co-doped fiber, a third fiber Bragg grating and a third circulator, wherein the second fiber Bragg grating, the third erbium-ytterbium co-doped fiber and the third fiber Bragg grating are sequentially connected to form a linear cavity; The light source assembly emits a second pump light in the 0.9 μm band, the second pump light is input into the linear cavity from the input end of the pump combiner, the linear cavity outputs the first pump light to the first end of the third circulator, and outputs from the second end of the third circulator.
5. The optical fiber amplifier according to claim 4, characterized in that: The light source assembly includes at least one 20W laser diode with a wavelength of 940nm.
6. The optical fiber amplifier according to claim 4, characterized in that: The pump fiber laser also includes a pump stripper; The pump stripper is located between the second fiber grating and the third fiber grating.
7. The optical fiber amplifier according to claim 4, characterized in that: The reflectivity of the second fiber grating is smaller than that of the third fiber grating. The first end of the third fiber grating is located in the linear cavity, and the end face of the second end of the third fiber grating is inclined at an angle of 8°.
8. The optical fiber amplifier according to claim 2, characterized in that: The first end of the first fiber grating is connected to the second end of the first wavelength division multiplexer, and the end face of the second end of the first fiber grating is inclined at an angle of 8°.
9. The optical fiber amplifier according to claim 2, characterized in that: The first erbium-ytterbium co-doped optical fiber is a double-clad optical fiber.
10. A fiber laser, characterized in that: It comprises a seed source and the optical fiber amplifier according to any one of claims 1 to 9, wherein the seed source emits a single-frequency laser of 1620 nm.