Optical fiber amplifier

Abstract

The embodiment of the application discloses an optical fiber amplifier, which comprises an isolation module, an amplification module and an output module, wherein the isolation module has an input end and a first polarization maintaining optical fiber, the input end of the isolation module is used for being connected with a seed source, and the isolation module is used for transmitting a light beam generated by the seed source; the amplification module has a second polarization maintaining optical fiber and a third polarization maintaining optical fiber, the first polarization maintaining optical fiber and the second polarization maintaining optical fiber are connected in a first connection mode, the amplification module is used for amplifying the light beam output by the isolation module, and the first connection mode is used for reducing the polarization degree of the light beam output by the isolation module; the output module has a fourth polarization maintaining optical fiber, the third polarization maintaining optical fiber and the fourth polarization maintaining optical fiber are connected in a second connection mode, the output module is used for outputting the light beam amplified by the amplification module, and the second connection mode is used for maintaining the polarization degree of the light beam amplified by the amplification module. By adopting the technical scheme, the problem that the improvement efficiency of the output power of the laser is low is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of laser, in particular to a fiber amplifier. BACKGROUND

[0002] Based on the multi-path high-power narrow linewidth fiber laser for spectral synthesis is an important way to realize the ten thousand watts level fiber laser, but the narrow linewidth fiber laser laser in the fiber amplification and transmission, easy to produce nonlinear effect, and then lead to the decline of laser performance parameters, while limiting the laser power to enhance.

[0003] In the prior art, the seed source linearly polarized laser based on single frequency laser and phase modulation technology can keep the spectral linewidth unchanged after amplification due to its time domain stability, and has a high stimulated Brillouin scattering and stimulated Raman scattering threshold, so it is widely used in high-power narrow linewidth fiber laser. In this way, since the seed laser is linearly polarized laser, even if a non-polarization maintaining amplifier is used, a certain depolarization effect will be produced, but due to the existence of polarization gain correlation effect, the output laser polarization degree is still very high, which will reduce the stimulated Brillouin threshold, thereby limiting the power improvement of the narrow linewidth fiber laser.

[0004] For the problems of low efficiency of output power improvement of the laser in the related art, no effective solution has been proposed. SUMMARY

[0005] The embodiments of the present application provide a fiber amplifier to at least solve the problem of low efficiency of output power improvement of the laser in the related art.

[0006] According to one of the embodiments of the present application, a fiber amplifier is provided, comprising: an isolation module, an amplification module and an output module, wherein,

[0007] The isolation module has an input end and a first polarization maintaining fiber, the input end of the isolation module is used to be connected with a seed source, and the isolation module is used to transmit the light beam generated by the seed source;

[0008] The amplification module has a second polarization maintaining fiber and a third polarization maintaining fiber, the first polarization maintaining fiber and the second polarization maintaining fiber are connected in a first connection mode, the amplification module is used to amplify the light beam output by the isolation module, and the first connection mode is used to reduce the polarization degree of the light beam output by the isolation module;

[0009] The output module has a fourth polarization maintaining fiber, the third polarization maintaining fiber and the fourth polarization maintaining fiber are connected in a second connection mode, the output module is used to output the light beam amplified by the amplification module, and the second connection mode is used to maintain the polarization degree of the light beam amplified by the amplification module.

[0010] Optionally, the first connection mode comprises that a target angle is formed between a polarization principal axis of the first polarization maintaining optical fiber and a polarization principal axis of the second polarization maintaining optical fiber, wherein the polarization principal axis of the optical fiber is used to indicate a polarization direction of the polarization maintaining optical fiber.

[0011] Optionally, the target angle is determined according to a reduction amount of a polarization degree of the light beam output by the isolation module.

[0012] Optionally, the target angle is an angle falling within a target angle range, and the target angle range is [45°±n°], wherein n is a preset angle error.

[0013] Optionally, the target angle is 45°.

[0014] Optionally, the second connection mode comprises that a polarization principal axis of the third polarization maintaining optical fiber and a polarization principal axis of the fourth polarization maintaining optical fiber are located on the same straight line, wherein the polarization principal axis of the optical fiber is used to indicate a polarization direction of the polarization maintaining optical fiber.

[0015] Optionally, the first polarization maintaining optical fiber, the second polarization maintaining optical fiber, the third polarization maintaining optical fiber and the fourth polarization maintaining optical fiber are all high-birefringence polarization maintaining optical fibers.

[0016] Optionally, the isolation module further comprises a light guide end, wherein

[0017] the light guide end is connected with a detection device;

[0018] the light guide end is used to output the isolated reverse back light to the detection device;

[0019] the detection device is used to detect stimulated Brillouin scattering light intensity in a back light spectrum of the reverse back light.

[0020] Optionally, the amplification module comprises a first cladding light filter, a gain optical fiber, a pump / signal coupler, a pump source group and a second cladding light filter, wherein

[0021] the first polarization maintaining optical fiber is connected with the second polarization maintaining optical fiber at an input end of the first cladding light filter, an output end of the first cladding light filter is connected with one end of the gain optical fiber, the other end of the gain optical fiber is connected with a first input end of the pump / signal coupler, the pump source group is connected with a second input end of the pump / signal coupler, an output end of the pump / signal coupler is connected with an input end of the second cladding light filter, and an output end of the second cladding light filter is connected with an input end of the output module;

[0022] the second cladding light filter is directly processed on an output optical fiber of the pump / signal coupler.

[0023] Optionally, the length of the output fiber of the pump / signal coupler is less than 20 cm.

[0024] In the embodiment of the present application, the optical fiber amplifier comprises an isolation module, an amplification module and an output module, wherein the isolation module has an input end and a first polarization maintaining optical fiber, the input end of the isolation module is used to be connected with a seed source, and the isolation module is used to transmit the light beam generated by the seed source; the amplification module has a second polarization maintaining optical fiber and a third polarization maintaining optical fiber, the first polarization maintaining optical fiber and the second polarization maintaining optical fiber are connected in a first connection mode, the amplification module is used to amplify the light beam output by the isolation module, and the first connection mode is used to reduce the polarization degree of the light beam output by the isolation module; the output module has a fourth polarization maintaining optical fiber, the third polarization maintaining optical fiber and the fourth polarization maintaining optical fiber are connected in a second connection mode, and the output module is used to output the light beam amplified by the amplification module; the second connection mode is used to maintain the polarization degree of the light beam amplified by the amplification module, that is, the polarization maintaining optical fibers are connected between the isolation module, the amplification module and the output module, the polarization maintaining optical fiber between the isolation module and the amplification module is connected in the first connection mode, the first connection mode can reduce the polarization degree of the light beam output by the isolation module, thereby generating a depolarization effect to reduce the polarization degree of the laser, and in the subsequent propagation and amplification process, the polarization maintaining optical fibers are connected in the second connection mode, thereby maintaining the polarization degree, the polarization degree of the light beam is controlled by adjusting the connection mode of the polarization maintaining optical fibers between the functional modules, and the stimulated Brillouin threshold of the laser can be effectively improved, thereby improving the output power of the laser. By using the above technical solution, the problems such as low improvement efficiency of the output power of the laser in the related art are solved, and the technical effect of improving the improvement efficiency of the output power of the laser is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0025] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate one embodiment consistent with the present application and, together with the description, serve to explain the principles of the embodiments of the application.

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows, and obviously, other drawings can also be obtained by those skilled in the art without creative labor.

[0027] Figure 1 is a structural block diagram of an optical fiber amplifier according to an embodiment of the present application Figure One ;

[0028] Figure 2 is a schematic diagram of the fusion angle of a polarization maintaining optical fiber according to an embodiment of the present application

[0029] Figure 3is a structural block of an optical fiber amplifier according to an embodiment of the present application Figure Two ;

[0030] Figure 4 is a structural block of an optical fiber amplifier according to an embodiment of the present application Figure Three ;

[0031] Figure 5 is a structural block of an optical fiber amplifier according to an embodiment of the present application Figure Four ;

[0032] Figure 6 is a schematic diagram of an optical fiber amplifier according to an embodiment of the present application. DETAILED DESCRIPTION

[0033] In order to make the personnel in the technical field better understand the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the embodiments of the present application.

[0034] It should be noted that the terms "first", "second" and the like in the specification and claims of the embodiments of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily have to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0035] In the embodiments of the present application, an optical fiber amplifier is provided, Figure 1 is a structural block of an optical fiber amplifier according to an embodiment of the present application Figure One , as shown in Figure 1 The above optical fiber amplifier comprises an isolation module 102, an amplification module 104 and an output module 106, wherein,

[0036] The isolation module 102 has an input end 102-1 and a first polarization maintaining optical fiber 102-2, the input end 102-1 of the isolation module 102 is used to be connected with a seed source, and the isolation module 102 is used to transmit the light beam generated by the seed source;

[0037] The amplification module 104 has a second polarization maintaining optical fiber 104-1 and a third polarization maintaining optical fiber 104-2, the first polarization maintaining optical fiber 102-2 and the second polarization maintaining optical fiber 104-1 are connected by a first connection mode, the amplification module 104 is used for amplifying the light beam output by the isolation module 102, and the first connection mode is used to reduce the polarization degree of the light beam output by the isolation module.

[0038] The output module 106 has a fourth polarization maintaining optical fiber 106-1, the third polarization maintaining optical fiber 104-2 and the fourth polarization maintaining optical fiber 106-1 are connected by a second connection mode, and the output module 106 is used for outputting the light beam amplified by the amplification module 104, and the second connection mode is used to maintain the polarization degree of the light beam amplified by the amplification module 104.

[0039] Through the above device, the polarization maintaining optical fiber is used to connect the isolation module, the amplification module and the output module, and the polarization maintaining optical fiber between the isolation module and the amplification module is connected by the first connection mode, the first connection mode can reduce the polarization degree of the light beam output by the isolation module, thereby producing depolarization effect, reducing the polarization degree of the laser, and in the subsequent propagation and amplification process, the polarization maintaining optical fiber is connected by the second connection mode, thereby maintaining the polarization degree, the polarization degree of the light beam is controlled by adjusting the connection mode of the polarization maintaining optical fiber between the functional modules, and the stimulated Brillouin threshold of the laser can be effectively improved, and the output power of the laser is improved. Through the above technical scheme, the problems such as low efficiency of improving the output power of the laser in the related art are solved, and the technical effect of improving the efficiency of improving the output power of the laser is realized.

[0040] Optionally, in the embodiment, the fiber amplifier can be applied in a laser device, such as a narrow linewidth fiber laser.

[0041] Optionally, in the embodiment, the first connection mode between the first polarization maintaining optical fiber and the second polarization maintaining optical fiber is used to reduce the polarization degree of the light beam output by the isolation module, and the first connection mode can be but not limited to reducing the polarization degree of the light beam output by the isolation module by controlling the connection mode and the connection parameters, such as controlling to select the modes such as fusion or connector, and controlling the connection parameters used in the selected connection mode, such as fusion angle, fusion length, fusion width, connector angle, connector length, etc.

[0042] In one example embodiment, the first connection mode includes forming a target angle between the polarization principal axis of the first polarization maintaining optical fiber and the polarization principal axis of the second polarization maintaining optical fiber, wherein the polarization principal axis of the optical fiber is used to indicate the polarization direction of the polarization maintaining optical fiber.

[0043] Optionally, in the embodiment, the first polarization maintaining optical fiber and the second polarization maintaining optical fiber are connected in a manner that the target angle is formed between the polarization principal axes, so that linearly polarized light working in a single polarization axis (fast axis / slow axis) is distributed in the fast axis and the slow axis, a depolarization effect is generated, and the laser polarization degree is reduced.

[0044] In an example embodiment, the target angle is determined according to a reduction amount of the polarization degree of the light beam output by the isolation module.

[0045] Optionally, in the embodiment, the target angle can be used to adjust the reduction amount of the polarization degree of the light beam output by the isolation module, so as to adjust the polarization effect according to requirements.

[0046] In an example embodiment, the target angle is an angle falling within a target angle range, and the target angle range is [45°±n°], where n is a preset angle error.

[0047] Optionally, in the embodiment, the preset angle error can be, but is not limited to, used to represent the accuracy of the target angle, and the target angle range in which the target angle is located can be controlled by controlling the angle error, so as to flexibly control the target angle within the target angle range according to actual requirements.

[0048] In an example embodiment, the target angle is 45°.

[0049] Optionally, in the embodiment, the polarization maintaining optical fibers between the isolation module and the amplification module can be, but are not limited to, fused at an included angle of 45° between the polarization principal axes, so that linearly polarized light working in a single polarization axis (fast axis / slow axis) is evenly distributed in the fast axis and the slow axis, a depolarization effect is generated, the laser polarization degree is reduced to zero, and the polarization degree remains unchanged in subsequent propagation and amplification processes. Reducing the laser polarization degree can effectively improve the stimulated Brillouin threshold of the laser, thereby improving the output power of the laser, while ensuring stable operation of the laser.

[0050] In an example embodiment, the second connection manner includes that the polarization principal axis of the third polarization maintaining optical fiber and the polarization principal axis of the fourth polarization maintaining optical fiber are located on the same straight line, where the polarization principal axis of the optical fiber is used to indicate the polarization direction of the polarization maintaining optical fiber.

[0051] Optionally, in the embodiment, the polarization maintaining optical fibers other than the polarization maintaining optical fiber between the output end of the isolation module and the input end of the amplification module in the optical fiber amplifier are fused at an included angle of 0° between the polarization principal axes.

[0052] Figure 2 is a schematic diagram of a polarization maintaining optical fiber fusion angle according to an embodiment of the present application, as Figure 2As shown, taking the fast axis of the polarization main axis of each polarization maintaining optical fiber as an example, the fast axis of the first polarization maintaining optical fiber and the fast axis of the second polarization maintaining optical fiber are connected by 45° fusion splicing, and the fast axis of the third polarization maintaining optical fiber and the fast axis of the fourth polarization maintaining optical fiber are connected by 0° fusion splicing.

[0053] In an example embodiment, the polarization maintaining optical fibers in the fiber amplifier (i.e., the first polarization maintaining optical fiber, the second polarization maintaining optical fiber, the third polarization maintaining optical fiber, and the fourth polarization maintaining optical fiber) are all high-birefringence polarization maintaining optical fibers.

[0054] Optionally, in the embodiment, the high-birefringence polarization maintaining optical fiber can include, but is not limited to, a panda polarization maintaining type 25 μm core, a 400 μm cladding polarization maintaining optical fiber, a panda polarization maintaining type 20 μm core, a 400 μm cladding optical fiber, and a polarization maintaining optical fiber with a birefringence coefficient satisfying a refractive index threshold, and the like.

[0055] Optionally, in the embodiment, the polarization maintaining optical fibers in the fiber amplifier are all fused by a fiber fusion splicer.

[0056] In an example embodiment, the isolation module further comprises a light guide end, wherein,

[0057] The light guide end is connected with a detection device;

[0058] The light guide end is configured to output the isolated reverse back light to the detection device.

[0059] The detection device is configured to detect the stimulated Brillouin scattering light intensity in the back light spectrum of the reverse back light.

[0060] Optionally, in the embodiment, the isolation module can be used to connect the detection device, and the stimulated Brillouin scattering light intensity in the back light spectrum of the reverse back light is detected by the detection device. Thus, the target angle can also be adjusted according to the detected stimulated Brillouin scattering light intensity.

[0061] Optionally, in the embodiment, the isolation module comprises a fiber isolator, wherein the output end of the fiber isolator is connected with the input end of the amplification module; the input end of the fiber isolator is configured to connect a linearly polarized seed source, and the light guide end of the fiber isolator is configured to output the isolated reverse back light.

[0062] Optionally, in the embodiment, Figure 3 is a structural block of a fiber amplifier according to an embodiment of the present application Figure Two As shown, Figure 3As shown, the first polarization maintaining optical fiber 102-2 of the fiber isolator 202 is connected with the second polarization maintaining optical fiber 104-1 of the amplification module 104; the input end 102-1 of the fiber isolator 202 is used for connecting the linearly polarized seed source 204, and the light guide end 206 of the fiber isolator 202 is used for outputting the isolated back light, and the light guide end 206 is connected with the detection device 208; the above-mentioned seed source includes the linearly polarized seed source 204.

[0063] Optionally, in the embodiment, the above-mentioned fiber isolator includes a linearly polarized three-port circulator.

[0064] In an exemplary embodiment, the amplification module includes a first cladding light filter, a gain optical fiber, a pump / signal coupler, a pump source group and a second cladding light filter, wherein the first polarization maintaining optical fiber is connected with the second polarization maintaining optical fiber of the input end of the first cladding light filter, the output end of the first cladding light filter is connected with one end of the gain optical fiber, the other end of the gain optical fiber is connected with the first input end of the pump / signal coupler, the pump source group is connected with the second input end of the pump / signal coupler, the output end of the pump / signal coupler is connected with the input end of the second cladding light filter, and the output end of the second cladding light filter is connected with the input end of the output module; the second cladding light filter is directly processed on the output optical fiber of the pump / signal coupler.

[0065] Optionally, in the embodiment, the pump / signal coupler and the second cladding light filter are a connected device, and the second cladding light filter is directly processed on the output optical fiber of the pump / signal coupler so that there is no fusion point in the connecting optical fiber between the pump / signal coupler and the second cladding light filter.

[0066] In an exemplary embodiment, the length of the output optical fiber of the pump / signal coupler is less than 20 cm.

[0067] Optionally, in the embodiment, the length of the output optical fiber of the pump / signal coupler as the connecting optical fiber between the pump / signal coupler and the second cladding light filter is less than a certain target threshold (such as 20 cm), and the output optical fiber of the pump / signal coupler is as short as possible.

[0068] Optionally, in the embodiment, the light guide end of the optical fiber isolator can but is not limited to be used for outputting the isolated back light and monitoring the intensity of the stimulated Brillouin scattering light in the back light spectrum; the first cladding light filter can but is not limited to be used for filtering the signal light and the excess pump light in the optical fiber cladding; the gain optical fiber can but is not limited to be used for converting the pump light into the signal light, thereby realizing laser amplification; the pump / signal coupler can but is not limited to be used for coupling the pump light into the cladding of the gain optical fiber; the pump source group can but is not limited to provide the pump light for the amplifier; the cladding light filter can but is not limited to be used for filtering the cladding light; and the optical fiber end cap can but is not limited to be used for laser spatial output. The pump / signal coupler and the second cladding light filter are connected devices, the connecting optical fiber has no fusion joint and has a length as short as possible.

[0069] Optionally, in the embodiment, Figure 4 is a structural block of an optical fiber amplifier according to an embodiment of the present application Figure Three As shown in Figure 4 , the amplification module can but is not limited to include: a cladding light filter 302 (i.e., the first cladding light filter described above), a gain optical fiber 304, a pump / signal coupler 306, a pump source group 308, and a cladding light filter 310 (i.e., the second cladding light filter described above). The input end 102-1 of the optical fiber isolator 202 is connected with the linearly polarized seed source 204, the first polarization maintaining optical fiber 102-2 of the optical fiber isolator 202 is connected with the input end 302-1 of the cladding light filter 302, the output end 302-2 of the cladding light filter 302 is connected with one end 304-1 of the gain optical fiber 304, the other end 304-2 of the gain optical fiber 304 is connected with the first input end 306-1 of the pump / signal coupler 306, the pump source group 308 is connected with the second input end 306-2 of the pump / signal coupler 306, the output end 306-3 of the pump / signal coupler 306 is connected with the input end 310-1 of the cladding light filter 310, and the output end 310-2 of the cladding light filter 310 is connected with the fourth polarization maintaining optical fiber 106-1 of the output module 106; the pump / signal coupler 306 and the cladding light filter 310 are connected devices, the connecting optical fiber between the pump / signal coupler 306 and the cladding light filter 310 has no fusion joint and has a length less than a target threshold.

[0070] In one example embodiment, the output module includes an optical fiber end cap.

[0071] Optionally, in the embodiment, the optical fiber end cap can but is not limited to be used for laser spatial output, Figure 5 is a structural block of an optical fiber amplifier according to an embodiment of the present application Figure Four As shown in Figure 5As shown, the input terminal 102-1 of the fiber optic isolator 202 is connected to the linearly polarized seed source 204. The first polarization-maintaining fiber 102-2 of the fiber optic isolator 202 is connected to the input terminal 302-1 of the cladding optical filter 302. The output terminal 302-2 of the cladding optical filter 302 is connected to one end 304-1 of the gain fiber 304. The other end 304-2 of the gain fiber 304 is connected to the first input terminal 306-1 of the pump / signal coupler 306. The pump source group 308 is connected to the pump / signal coupler 306. The second input terminal 306-2 of the 06 is connected, the output terminal 306-3 of the pump / signal coupler 306 is connected to the input terminal 310-1 of the cladding optical filter 310, and the output terminal 310-2 of the cladding optical filter 310 is connected to the input terminal 402-1 of the fiber end cap 402; the pump / signal coupler 306 and the cladding optical filter 310 are integrated devices, and the connecting optical fiber between the pump / signal coupler 306 and the cladding optical filter 310 has no fusion splice and the length of the connecting optical fiber is less than the target threshold.

[0072] To better understand the fiber optic amplifier described above, the structure of the fiber optic amplifier will be further described below in conjunction with optional embodiments, but this is not intended to limit the technical solutions of the embodiments of this application.

[0073] This embodiment provides an optical fiber amplifier. Figure 6 This is a schematic diagram of an optical fiber amplifier according to an embodiment of this application, as shown below. Figure 6 As shown, the aforementioned fiber amplifier may include, but is not limited to, the following: fiber isolator 1, cladding optical filter 2 (i.e., the aforementioned first cladding optical filter), gain fiber 3, pump / signal coupler 4, pump source group 5, cladding optical filter 6 (i.e., the aforementioned second cladding optical filter), and fiber end cap 7. The input and output fibers of fiber isolator 1, cladding optical filter 2, gain fiber 3, pump / signal coupler 4, cladding optical filter 6, and the input fiber of fiber end cap 7 are all high birefringence polarization-maintaining fibers. Fiber isolator 1 may include, but is not limited to, end A1 (i.e., the aforementioned input end of the fiber isolator), end A2 (i.e., the aforementioned light guide end of the fiber isolator), and end A3 (i.e., the aforementioned output end of the fiber isolator). Pump / signal coupler 4 may include, but is not limited to, end B1 (i.e., the aforementioned first input of the pump / signal coupler), end B2 (i.e., the aforementioned output end of the pump / signal coupler), and end B3 (i.e., the aforementioned second input of the pump / signal coupler). Optical paths can be created, but are not limited to, in the following ways:

[0074] The output end A3 of the optical fiber isolator 1 and the input end of the cladding light filter 2 are fused at a polarization principal axis included angle of 45°, and the other polarization maintaining optical fibers are fused at a polarization principal axis included angle of 0° except the output end A3 of the optical fiber isolator 1 (i.e. the output end of the optical fiber isolator described above) and the input end of the cladding light filter 2, and the pump fiber of the pump / signal coupler 4 (i.e. the second input end of the pump / signal coupler described above) and the output end pump fiber of the pump source group 5 are directly fused as the same multimode optical fiber. The linearly polarized seed laser emitted by the linearly polarized seed source 8 outputs the same linearly polarized laser after passing through the optical fiber isolator 1, and generates depolarization after passing through the fusion point of the optical fiber isolator 1 and the cladding light filter 2, and keeps the polarization state unchanged in the subsequent polarization maintaining optical fiber amplification and transmission process.

[0075] Optionally, in the embodiment, the input optical fiber, the output optical fiber and the gain optical fiber 3 of the optical fiber isolator 1, the cladding light filter 2, the pump / signal coupler 4, the cladding light filter 6 and the optical fiber end cap 7 can but are not limited to use the panda polarization maintaining type 20 μm core, 400 μm cladding optical fiber. The optical fiber isolator 1 uses the fast axis working mode, and the input power is 50 W, and the wavelength is 1064 nm narrow line width seed laser, and the polarization state of the signal light is close to zero after passing through the 45° fusion point of the optical fiber isolator 1 and the cladding light filter 2, and the measured laser polarization degree remains unchanged after being amplified to 1500 W by the gain optical fiber 3, and there is no obvious stimulated Brillouin scattering light generated in the back light monitoring of the optical fiber isolator 1.

[0076] Optionally, in the embodiment, the output optical fiber and the input optical fiber of the optical fiber isolator 1 can but are not limited to use the panda polarization maintaining type 20 μm core, 400 μm cladding polarization maintaining optical fiber, and the input optical fiber, the output optical fiber and the gain optical fiber 3 of the cladding light filter 2, the pump / signal coupler 4, the cladding light filter 6 and the optical fiber end cap 7 can but are not limited to use the panda polarization maintaining type 25 μm core, 400 μm cladding polarization maintaining optical fiber. The optical fiber isolator 1 uses the fast axis working mode, and the input power is 100 W, and the wavelength is 1050 nm narrow line width seed laser, and the polarization state of the signal light is close to zero after passing through the 45° fusion point of the optical fiber isolator 1 and the cladding light filter 2, and the measured laser polarization degree remains unchanged after being amplified to 1500 W by the gain optical fiber 3, and there is no obvious stimulated Brillouin scattering light generated in the back light monitoring of the optical fiber isolator 1.

[0077] Optionally, the specific examples in the embodiment can refer to the examples described in the above embodiments and optional implementation manners, and the embodiment will not be described here.

[0078] Obviously, those skilled in the art should understand that each module or each step of the above-mentioned embodiments of the present application can be realized by a general computing device, which can be centralized on a single computing device or distributed on a network composed of multiple computing devices, and optionally, each module or each step can be realized by program codes executable by a computing device, so that each module or each step can be stored in a storage device and executed by a computing device, and in some cases, the steps shown or described can be executed in different orders, or each module can be manufactured as an individual integrated circuit module, or multiple modules or steps can be manufactured as a single integrated circuit module. Therefore, the embodiments of the present application are not limited to any specific combination of hardware and software.

[0079] The above-mentioned is only the preferred embodiment of the present application, and it should be pointed out that for those skilled in the art, without departing from the principle of the present application, a number of improvements and refinements can be made, which should be considered as the protection scope of the present application.

Claims

1. A fiber amplifier, characterized by, The application relates to a seed laser module. The seed laser module comprises an isolation module, an amplification module and an output module, wherein, The isolation module has an input end and a first polarization maintaining optical fiber, the input end of the isolation module is used for being connected with a seed source, and the isolation module is used for transmitting a light beam generated by the seed source; The amplification module has a second polarization maintaining optical fiber and a third polarization maintaining optical fiber, the first polarization maintaining optical fiber and the second polarization maintaining optical fiber are connected through a first connection mode, the amplification module is used for amplifying the light beam output by the isolation module, and the first connection mode is used for reducing the polarization degree of the light beam output by the isolation module; The output module has a fourth polarization maintaining optical fiber, the third polarization maintaining optical fiber and the fourth polarization maintaining optical fiber are connected through a second connection mode, the output module is used for outputting the light beam amplified by the amplification module, and the second connection mode is used for maintaining the polarization degree of the light beam amplified by the amplification module; The second connection mode comprises that the polarization principal axis of the third polarization maintaining optical fiber and the polarization principal axis of the fourth polarization maintaining optical fiber are located on the same straight line, wherein the polarization principal axis of the optical fiber is used for indicating the polarization direction of the polarization maintaining optical fiber; The third polarization maintaining optical fiber and the fourth polarization maintaining optical fiber are connected through a polarization principal axis included angle of 0 degrees.

2. The fiber amplifier of claim 1, wherein, The first connection mode comprises that the polarization principal axis of the first polarization maintaining optical fiber and the polarization principal axis of the second polarization maintaining optical fiber form a target angle, wherein the polarization principal axis of the optical fiber is used for indicating the polarization direction of the polarization maintaining optical fiber.

3. The fiber amplifier of claim 2, wherein, The target angle is determined according to the reduction amount of the polarization degree of the light beam output by the isolation module.

4. The fiber amplifier of claim 2, wherein, The target angle is an angle falling in a target angle range, and the target angle range is [45 DEG + n DEG ], wherein n is a preset angle error.

5. The fiber amplifier of claim 2, wherein, The target angle is 45 DEG.

6. The fiber amplifier of claim 1, wherein, The first polarization maintaining optical fiber, the second polarization maintaining optical fiber, the third polarization maintaining optical fiber and the fourth polarization maintaining optical fiber are all high-birefringence polarization maintaining optical fibers.

7. The fiber amplifier of claim 1, wherein, The isolation module further comprises a light guide end, wherein, The light guide end is connected with a detection device; The light guide end is used for outputting reverse back light isolated by the detection device; The detection device is used for detecting the stimulated Brillouin scattering light intensity in the back light spectrum of the reverse back light.

8. The fiber amplifier of claim 1, wherein, The amplification module comprises a first cladding light filter, a gain optical fiber, a pump / signal coupler, a pump source group and a second cladding light filter, wherein, The first polarization maintaining optical fiber is connected with the second polarization maintaining optical fiber of the input end of the first cladding light filter, the output end of the first cladding light filter is connected with one end of the gain optical fiber, the other end of the gain optical fiber is connected with the first input end of the pump / signal coupler, the pump source group is connected with the second input end of the pump / signal coupler, the output end of the pump / signal coupler is connected with the input end of the second cladding light filter, and the output end of the second cladding light filter is connected with the input end of the output module; The second cladding light filter is directly processed on the output optical fiber of the pump / signal coupler.

9. The fiber amplifier of claim 8, wherein, The length of the output optical fiber of the pump / signal coupler is less than 20 cm.

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