Nanosecond pulse fiber laser

Abstract

The utility model provides a nanosecond pulse fiber laser which comprises a seed source module, a first-stage amplification module, a second-stage amplification module, a third-stage amplification module and an output isolator which are connected in sequence, the seed source module is used for outputting seed light, and the specification of an output optical fiber of the seed source module is the same as that of an optical fiber of a main optical path of the first-stage amplification module; the specification of an output optical fiber of the first-stage amplification module is the same as that of an optical fiber of a main optical path of the second-stage amplification module, the specification of an output optical fiber of the second-stage amplification module is different from that of an optical fiber of a main optical path of the third-stage amplification module, and the third-stage amplification module comprises a mode field adapter. According to the nanosecond pulse fiber laser provided by the invention, the technical problem that optical signal transmission is affected due to mismatching of main optical path fiber specifications among a plurality of amplification modules in the prior art can be solved.

Description

Technical Field

[0001] This application belongs to the field of fiber laser technology, and more specifically, relates to a nanosecond pulsed fiber laser. Background Technology

[0002] Nanosecond pulsed fiber lasers have advantages such as excellent output beam quality, compact structure, and high flexibility, and therefore their development has been very rapid.

[0003] In related technologies, nanosecond pulsed fiber lasers utilize Q-switching technology, semiconductor laser diodes, etc., to generate seed light, which is then amplified by an amplification module to the target performance specifications.

[0004] However, in related technologies, nanosecond pulsed fiber lasers amplify seed light through multiple amplification modules connected in sequence. Mismatch in the specifications of the main optical fiber between these multiple amplification modules can affect the transmission of optical signals. Utility Model Content

[0005] The purpose of this application is to provide a nanosecond pulsed fiber laser to solve the technical problem in the related art where the main optical fiber specifications of multiple amplification modules are mismatched, affecting the transmission of optical signals.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0007] A nanosecond pulsed fiber laser is provided, comprising a seed source module, a first-stage amplification module, a second-stage amplification module, a third-stage amplification module, and an output isolator. The seed source module outputs seed light. The input of the first-stage amplification module is connected to the seed source module. The input of the second-stage amplification module is connected to the output of the first-stage amplification module. The input of the third-stage amplification module is connected to the output of the second-stage amplification module. The input of the output isolator is connected to the output of the third-stage amplification module. The output fiber of the seed source module has the same specifications as the fiber in the main optical path of the first-stage amplification module. The output fiber of the first-stage amplification module has the same specifications as the fiber in the main optical path of the second-stage amplification module. The output fiber of the second-stage amplification module has different specifications than the fiber in the main optical path of the third-stage amplification module. The third-stage amplification module includes a mode field adapter.

[0008] Through the above technical solution, the first-stage amplification module amplifies the seed light for the first time, the second-stage amplification module amplifies the seed light amplified for the second time, and the third-stage amplification module amplifies the seed light amplified for the third time, thus amplifying the seed light three times to achieve the target performance indicators. Furthermore, the fiber specifications of the main optical path of the first-stage amplification module are the same as those of the output fiber of the seed source module, and the output fiber specifications of the first-stage amplification module are the same as those of the main optical path of the second-stage amplification module. This avoids mismatch in the main optical path fiber specifications, thereby preventing interference with optical signal transmission. Moreover, if the output fiber specifications of the second-stage amplification module differ from those of the main optical path of the third-stage amplification module, the third-stage amplification module includes a mode field adapter. The mode field adapter connects to fibers of different specifications, and its impact on optical signal transmission is minimal, thus preventing interference with optical signal transmission when fiber specifications differ.

[0009] Therefore, the nanosecond pulsed fiber laser provided in this application can solve the technical problem in related technologies where the main optical path fiber specifications are mismatched among multiple amplification modules, affecting the transmission of optical signals.

[0010] In some implementations, the seed source module includes a directly modulated semiconductor laser diode and a first in-line isolator. The output of the semiconductor laser diode is connected to the input of the first in-line isolator, the input of the first-stage amplification module is connected to the output of the first in-line isolator, and the output of the first in-line isolator is used to output seed light.

[0011] In some embodiments, the center wavelength of the semiconductor laser diode is 1064 nm, and / or the linewidth of the semiconductor laser diode is less than 15 nm, and / or the output fiber of the semiconductor laser diode is Hi1060 fiber.

[0012] In some embodiments, the center wavelength of the first online isolator is 1059 nm, and / or the operating bandwidth of the first online isolator is 16 nm, and / or the input fiber of the first online isolator is Hi1060 fiber, and / or the output fiber of the first online isolator is 10 / 125 single-clad fiber.

[0013] In some embodiments, the first-stage amplification module further includes a first pump laser, a first photodetector, and a first beam combiner, a first gain fiber, a second in-line isolator, and a coupler connected in sequence. The input end of the first beam combiner is connected to the output end of the first in-line isolator, the output end of the first pump laser is connected to the input end of the first beam combiner, and the input end of the first beam combiner is used to receive seed light and pump light output from the first pump laser. The first output end of the coupler is connected to the input end of the second-stage amplification module, and the second output end of the coupler is connected to the first photodetector.

[0014] In some embodiments, the pump fiber and signal fiber of the first combiner are disposed at the input end of the first combiner, the output end of the first pump laser is connected to the pump fiber of the first combiner, the signal fiber of the first combiner is connected to the output end of the first in-line isolator, the signal fiber of the first combiner is a 10 / 125 double-clad fiber, the pump fiber of the first combiner is a 105 / 125 multimode fiber; and / or, the first gain fiber is a ytterbium-doped 10 / 125 double-clad fiber; and / or, the input fiber and output fiber of the second in-line isolator are both 10 / 125 single-clad fibers; and / or, the fiber at the input end of the coupler, the fiber at the first output end, and the fiber at the second output end are all 10 / 125 single-clad fibers.

[0015] In some implementations, the secondary amplification module includes a red laser, a second pump laser, and a wavelength division multiplexer, a second gain fiber, a second beam combiner, and a third in-line isolator connected in sequence. The input of the wavelength division multiplexer is connected to the output of the primary amplification module, the output of the red laser is connected to the input of the wavelength division multiplexer, and the input of the wavelength division multiplexer is used to receive the optical signal output from the primary amplification module and the red light output from the red laser. The output of the second pump laser is connected to the output of the second beam combiner, and the input of the tertiary amplification module is connected to the output of the third in-line isolator.

[0016] In some embodiments, the input end of the wavelength division multiplexer is provided with a signal port and a red light port. The signal port of the wavelength division multiplexer is connected to the output end of the first-stage amplification module, and the red light port of the wavelength division multiplexer is connected to the output end of the red laser. The optical fiber of the signal port and the optical fiber of the output end of the wavelength division multiplexer are 10 / 125 single-clad optical fibers, and the optical fiber of the red light port is Hi1060 optical fiber; and / or, the second gain fiber is a ytterbium-doped 10 / 125 double-clad optical fiber; and / or, the signal fiber of the second combiner is disposed at the input end of the second combiner, and the pump fiber and output of the second combiner are also disposed at the input end of the second combiner. An optical fiber is disposed at the output end of the second combiner. The output end of the second pump laser is connected to the pump fiber of the second combiner. The signal fiber of the second combiner is connected to the output end of the second gain fiber. The output fiber of the second combiner is connected to the input end of the third in-line isolator. The signal fiber and output fiber of the second combiner are 10 / 125 double-clad fibers, and the pump fiber of the second combiner is a 105 / 125 multimode fiber. And / or, the input fiber of the third in-line isolator is a 10 / 125 single-clad fiber, and the output fiber of the second in-line isolator is a 10 / 125 single-clad fiber.

[0017] In some embodiments, the three-stage amplification module further includes a second photodetector and a mode field adapter, a third gain fiber, a third combiner, and a third pump laser connected in sequence. The input end of the mode field adapter is connected to the output end of the second-stage amplification module, the output end of the third pump laser is connected to the output end of the third combiner, the output end of the third combiner is also connected to the input end of the output isolator, and the second photodetector is located at the connection between the output end of the third combiner and the input end of the output isolator.

[0018] In some embodiments, the input fiber of the mode field adapter is a 10 / 125 single-clad fiber, and the output fiber of the mode field adapter is a 14 / 250 double-clad fiber; and / or, the third gain fiber is a ytterbium-doped 14 / 250 double-clad fiber; and / or, the signal fiber of the third combiner is disposed at the input of the third combiner, the pump fiber and the output fiber of the third combiner are disposed at the output of the third combiner, the output fiber of the third combiner is fused to the input of the output isolator, the second photodetector is disposed at the fusion point between the output fiber of the third combiner and the input of the output isolator, the output of the third pump laser is connected to the pump fiber of the third combiner, the signal fiber and the output fiber of the third combiner are 14 / 250 double-clad fibers, the pump fiber of the third combiner is a 135 / 155 multimode fiber; and / or, the input fiber of the output isolator is a 135 / 155 multimode fiber. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of a nanosecond pulsed fiber laser provided in an embodiment of this application;

[0021] Figure 2 This is a schematic diagram of the structure of the seed source module provided in an embodiment of this application;

[0022] Figure 3 This is a schematic diagram of the structure of the first-stage amplification module provided in an embodiment of this application;

[0023] Figure 4 This is a schematic diagram of the structure of the secondary amplification module provided in the embodiments of this application;

[0024] Figure 5 This is a schematic diagram of the structure of the three-stage amplification module provided in an embodiment of this application.

[0025] The following are the labeling elements in the figure:

[0026] 10-Seed source module; 11-Semiconductor laser diode; 12-First in-line isolator; 20-First stage amplifier module; 21-First pump laser; 22-First beam combiner; 23-First gain fiber; 24-Second in-line isolator; 25-Coupler; 26-First photodetector; 30-Second stage amplifier module; 31-Red laser; 32-Wavelength division multiplexer; 33-Second gain fiber; 34-Second beam combiner; 35-Second pump laser; 36-Third in-line isolator; 40-Third stage amplifier module; 41-Mode field adapter; 42-Third gain fiber; 43-Third beam combiner; 44-Third pump laser; 45-Second photodetector; 50-Output isolator. Detailed Implementation

[0027] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0028] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0029] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0031] Nanosecond pulsed fiber lasers have developed rapidly due to their advantages such as excellent output beam quality, compact structure, and high flexibility. In related technologies, nanosecond pulsed fiber lasers utilize Q-switching technology and semiconductor laser diodes to generate seed light, which is then amplified to the target performance specifications by an amplification module. However, in these technologies, the seed light is amplified by multiple sequentially connected amplification modules. Mismatches in the fiber specifications of the main optical path between these modules can affect optical signal transmission.

[0032] Please refer to the following: Figures 1 to 5 The nanosecond pulsed fiber laser provided in the embodiments of this application will now be described.

[0033] Please see Figure 1 The nanosecond pulsed fiber laser provided in this application embodiment includes a seed source module 10, a first-stage amplification module 20, a second-stage amplification module 30, a third-stage amplification module 40, and an output isolator 50. The seed source module 10 outputs seed light. The input terminal of the first-stage amplification module 20 is connected to the seed source module 10, and the first-stage amplification module 20 amplifies the seed light for the first time. The input terminal of the second-stage amplification module 30 is connected to the output terminal of the first-stage amplification module 20, and the second-stage amplification module 30 amplifies the seed light a second time. The input terminal of the third-stage amplification module 40 is connected to the output terminal of the second-stage amplification module 30, and the third-stage amplification module 40 amplifies the seed light a third time. The input terminal of the output isolator 50 is connected to the output terminal of the third-stage amplification module 40, and the output isolator 50 is used to output the amplified seed light.

[0034] Please see Figure 2 In some embodiments, the seed source module 10 includes a directly modulated semiconductor laser diode 11 and a first in-line isolator 12. The output terminal of the semiconductor laser diode 11 is connected to the input terminal of the first in-line isolator 12, the input terminal of the first-stage amplification module 20 is connected to the output terminal of the first in-line isolator 12, and the output terminal of the first in-line isolator 12 is used to output seed light.

[0035] Among them, the semiconductor laser diode 11 can be directly modulated, which can achieve a more flexible frequency tuning range and the pulse width is tunable. It can output corresponding optical signals according to needs, thereby meeting the diverse application market demands.

[0036] For example, the semiconductor laser diode 11 can be a commercially available superluminescent diode (SLD), which has the advantages of high power, wide spectrum, low ripple, and good temperature stability. For example, the center wavelength of the semiconductor laser diode 11 can be 1064 nm. For example, the linewidth of the semiconductor laser diode 11 is less than 15 nm. For example, the output fiber of the semiconductor laser diode 11 is Hi1060 fiber. For example, the output state of the semiconductor laser diode 11 is pulsed. For example, the pulse width range of the semiconductor laser diode 11 can be 6 ns-400 ns, which can have a wide tuning range. For example, the repetition frequency of the semiconductor laser diode 11 can be 1 kHz-33333 kHz.

[0037] For example, the center wavelength of the first in-line isolator 12 can be 1059 nm. For example, the operating bandwidth of the first in-line isolator 12 can be 16 nm. For example, the input fiber of the first in-line isolator 12 can be Hi1060 fiber. For example, the output fiber of the first in-line isolator 12 can be 10 / 125 single-clad fiber. Furthermore, the fiber in the main optical path of the first-stage amplification module 20 is 10 / 125 fiber, so that the specifications of the output fiber of the seed source module 10 are the same as those of the fiber in the main optical path of the first-stage amplification module 20, facilitating the connection between the seed source module 10 and the first-stage amplification module 20.

[0038] For example, the average power handled by the first in-line isolator 12 can be 300mW, which is greater than the output power of the semiconductor laser diode 11, and the average power handled by the first in-line isolator 12 can be matched with that of the semiconductor laser diode 11. For example, the insertion loss of the first in-line isolator 12 is less than 3dB. For example, the isolation of the first in-line isolator 12 is greater than 25dB.

[0039] Please see Figure 3 In some embodiments, the first-stage amplification module 20 is equipped with a first photodetector 26, which is used to detect the optical signal output by the first-stage amplification module 20. In this way, the first photodetector 26 can detect the optical path of the nanosecond pulse fiber laser, thereby determining the operating state of the nanosecond pulse fiber laser based on the detection results, and adjusting the nanosecond pulse fiber laser according to the detection results. This helps protect the optical path system of the nanosecond pulse fiber laser, thereby improving its performance.

[0040] For example, the nanosecond pulsed fiber laser provided in this application embodiment may further include a controller, which is electrically connected to a first photodetector 26. The first photodetector 26 may also be electrically connected to a seed source module 10. The controller can acquire the information detected by the first photodetector 26, and thus control the seed source module 10 according to the information detected by the first photodetector 26, thereby adjusting the nanosecond pulsed fiber laser.

[0041] For example, the first photodetector 26 is a commercially available fiber-coupled photodetector, and the fiber of the first photodetector 26 can be a Hi1060 fiber.

[0042] Please continue reading. Figure 3 In some embodiments, the first-stage amplification module 20 further includes a coupler 25. The input of the coupler 25 is used to receive optical signals, the first output of the coupler 25 is connected to the input of the second-stage amplification module 30, and the second output of the coupler 25 is connected to the first photodetector 26. In this way, the first photodetector 26 can receive the optical signals obtained by the coupler 25, thereby detecting the optical path operation status of the nanosecond pulse fiber laser.

[0043] For example, the splitting ratio of coupler 25 can be 1:1000, in other words, the coupling ratio of coupler 25 is 999:1. In this way, of the optical signal received by coupler 25, 999‰ of the power is transmitted to the input of the secondary amplification module 30, and 1‰ of the power is transmitted to the first photodetector 26. The first photodetector 26 can detect the optical path operation status of the nanosecond pulsed fiber laser by using a smaller power ratio.

[0044] For example, the coupler 25 can withstand an average power of 2W and can be used in the first-stage amplification module 20.

[0045] For example, the optical fiber at the input end of coupler 25 can be a 10 / 125 single-clad fiber. For example, the optical fiber at the first output end of coupler 25 can be a 10 / 125 single-clad fiber. For example, the optical fiber at the second output end of coupler 25 can be a 10 / 125 single-clad fiber.

[0046] Please continue reading. Figure 3In some embodiments, the first-stage amplification module 20 further includes a first pump laser 21 and a first beam combiner 22, a first gain fiber 23, and a second in-line isolator 24 connected in sequence. The input end of the first beam combiner 22 is connected to the seed source module 10, and the output end of the first pump laser 21 is connected to the input end of the first beam combiner 22. The input end of the first beam combiner 22 is used to receive the seed light and the pump light output by the first pump laser 21. The output end of the second in-line isolator 24 is connected to the input end of the coupler 25, and the first output end of the coupler 25 forms the output end of the first-stage amplification module 20.

[0047] The first pump laser 21 has an output power greater than 10W, a center wavelength of 915nm, and its output fiber is a 105 / 125 multimode fiber. The first pump laser 21 can provide pump excitation for the first gain fiber 23. Exemplarily, the first gain fiber 23 is a ytterbium-doped fiber. Exemplarily, the first gain fiber 23 is a ytterbium-doped 10 / 125 double-clad fiber.

[0048] For example, the pump fiber and signal fiber of the first combiner 22 are disposed at the input end of the first combiner 22, the output end of the first pump laser 21 is connected to the pump fiber of the first combiner 22, and the signal fiber of the first combiner 22 is connected to the output end of the first in-line isolator 12. For example, the signal fiber of the first combiner 22 is a 10 / 125 double-clad fiber, and the pump fiber of the first combiner 22 is a 105 / 125 multimode fiber. The pump light coupling efficiency of the first combiner 22 is greater than 95%, the signal light power handling capacity is greater than 1W, and the pump light power handling capacity is greater than 10W.

[0049] For example, the input fiber of the second in-line isolator 24 can be a 10 / 125 single-clad fiber. For example, the output fiber of the second in-line isolator 24 can be a 10 / 125 single-clad fiber. It is understood that maintaining consistent fiber specifications in the first-stage amplification module 20 is beneficial for optical signal transmission.

[0050] For example, the center wavelength of the second in-line isolator 24 is 1062 nm. For example, the operating bandwidth of the second in-line isolator 24 is 20 nm. For example, the average power handled by the second in-line isolator 24 is 2 W. For example, the insertion loss of the second in-line isolator 24 is less than 1.5 dB. For example, the isolation of the second in-line isolator 24 is greater than 25 dB.

[0051] Please see Figure 4 In some embodiments, the secondary amplification module 30 includes a red laser 31, a second pump laser 35, and a wavelength division multiplexer 32, a second gain fiber 33, a second beam combiner 34, and a third in-line isolator 36 connected in sequence.

[0052] The input of wavelength division multiplexer 32 is connected to the output of first-stage amplification module 20, the output of red laser 31 is connected to the input of wavelength division multiplexer 32, the input of wavelength division multiplexer 32 is used to receive the optical signal output by first-stage amplification module 20 and the red light output by red laser 31, the output of second pump laser 35 is connected to the output of second beam combiner 34, and the input of third-stage amplification module 40 is connected to the output of third in-line isolator 36.

[0053] For example, the red laser 31 is a commercially available red laser diode. For example, the output fiber of the red laser 31 is a Hi1060 fiber, and the output power of the red laser 31 is greater than 60mW.

[0054] In some embodiments, the input of the wavelength division multiplexer 32 is provided with a signal port and a red light port. The signal port of the wavelength division multiplexer 32 is connected to the output of the first-stage amplifier module 20 (the first output of the coupler 25), and the red light port of the wavelength division multiplexer 32 is connected to the output of the red laser 31 (the output optical fiber of the red laser 31). The optical fiber of the signal port is a 10 / 125 single-clad fiber, and the optical fiber of the red light port is a Hi1060 fiber. The optical fiber of the signal port of the wavelength division multiplexer 32 has the same specification as the optical fiber of the first output of the coupler 25 and can be directly connected. The optical fiber of the red light port of the wavelength division multiplexer 32 has the same specification as the output optical fiber of the red laser 31 and can be directly connected. In this way, the wavelength division multiplexer 32 can receive the optical signal output by the first-stage amplifier module 20 and the optical signal output by the red laser 31.

[0055] For example, wavelength division multiplexer 32 can handle an average power greater than 2W.

[0056] For example, the second gain fiber 33 can be ytterbium-doped fiber. For example, the second gain fiber 33 can be ytterbium-doped 10 / 125 double-clad fiber. The second gain fiber 33 has the same fiber specification as the output fiber of the wavelength division multiplexer 32 and can be directly connected.

[0057] It is understood that the second pump laser 35 can provide pump excitation for the second gain fiber 33. Exemplarily, the output power of the second pump laser 35 is greater than 50W. Exemplarily, the center wavelength of the second pump laser 35 is 915nm. Exemplarily, the output fiber of the second pump laser 35 is a 105 / 125 multimode fiber.

[0058] For example, the signal fiber of the second combiner 34 is disposed at the input end of the second combiner 34, the pump fiber and the output fiber of the second combiner 34 are disposed at the output end of the second combiner 34, the output end of the second pump laser 35 is connected to the pump fiber of the second combiner 34, the signal fiber of the second combiner 34 is connected to the output end of the second gain fiber 33, the output fiber of the second combiner 34 is connected to the input end of the third in-line isolator 36, and the output end of the third in-line isolator 36 forms the output end of the secondary amplification module 30.

[0059] The signal fiber of the second combiner 34 can be a 10 / 125 double-clad fiber, the output fiber of the second combiner 34 can be a 10 / 125 double-clad fiber, and the pump fiber of the second combiner 34 can be a 105 / 125 multimode fiber. Exemplarily, the pump light coupling efficiency of the second combiner 34 is greater than 95%. Exemplarily, the signal light power handling capacity of the second combiner 34 is greater than 20W. Exemplarily, the pump light power handling capacity of the second combiner 34 is greater than 50W.

[0060] Exemplarily, the input fiber of the third in-line isolator 36 is a 10 / 125 single-clad fiber. Exemplarily, the output fiber of the second in-line isolator 24 is a 10 / 125 single-clad fiber. Exemplarily, the center wavelength of the third in-line isolator 36 is 1062 nm. Exemplarily, the operating bandwidth of the third in-line isolator 36 is 20 nm. Exemplarily, the average power handled by the third in-line isolator 36 is 20 W. Exemplarily, the insertion loss of the third in-line isolator 36 is less than 1 dB. Exemplarily, the isolation of the third in-line isolator 36 is greater than 25 dB.

[0061] It is understandable that the second gain fiber 33, the second combiner 34, and the third in-line isolator 36, which transmit optical signals in the main optical path direction of the secondary amplifier module 30, are all 10 / 125 fiber optic cables and can be directly connected. Therefore, the fiber optic cable specification of the main optical path of the secondary amplifier module 30 is 10 / 125 fiber optic cable. The fiber optic cables at the output end of the primary amplifier module 20 and the output end of the wavelength division multiplexer 32 are 10 / 125 single-clad fiber optic cables. The specification of the output fiber optic cable of the primary amplifier module 20 is the same as that of the main optical path fiber optic cable of the secondary amplifier module 30, which can avoid mismatch in the main optical path fiber optic cable specification and thus avoid affecting the optical signal transmission.

[0062] Please see Figure 5In some embodiments, the third-stage amplification module 40 is equipped with a second photodetector 45, which is used to detect the optical signal output by the third-stage amplification module 40. In this way, the second photodetector 45 can detect the optical path of the nanosecond pulse fiber laser, thereby determining the operating state of the nanosecond pulse fiber laser based on the detection results, and adjusting the nanosecond pulse fiber laser according to the detection results. This helps protect the optical path system of the nanosecond pulse fiber laser, thereby improving its performance.

[0063] For example, the controller can be electrically connected to the second photodetector 45, which can also be electrically connected to the seed source module 10. The controller can acquire the information detected by the second photodetector 45, and thus control the seed source module 10 according to the information detected by the second photodetector 45, thereby adjusting the nanosecond pulsed fiber laser.

[0064] For example, the second photodetector 45 is a space photodetector. For example, the second photodetector 45 is a commercial free-space photodetector.

[0065] In some embodiments, the three-stage amplification module 40 further includes a mode field adapter 41, a third gain fiber 42, a third combiner 43, and a third pump laser 44 connected in sequence. The input end of the mode field adapter 41 is connected to the output end of the two-stage amplification module 30, the output end of the third pump laser 44 is connected to the output end of the third combiner 43, the output end of the third combiner 43 is also connected to the input end of the output isolator 50, and the second photodetector 45 is disposed at the connection between the output end of the third combiner 43 and the input end of the output isolator 50.

[0066] The signal fiber of the third combiner 43 is located at the input end of the third combiner 43 and is connected to the third gain fiber 42. The pump fiber and the output fiber of the third combiner 43 are located at the output end of the third combiner 43. The output fiber of the third combiner 43 is fused to the input end of the output isolator 50. The second photodetector 45 is located at the fusion point between the output fiber of the third combiner 43 and the input end of the output isolator 50. The output end of the third pump laser 44 is connected to the pump fiber of the third combiner 43.

[0067] For example, the second photodetector 45 is positioned above the fusion point between the output fiber of the third combiner 43 and the input end of the output isolator 50.

[0068] For example, the third gain fiber 42 can be a ytterbium-doped fiber. For example, the third gain fiber 42 can be a ytterbium-doped 14 / 250 double-clad fiber.

[0069] Understandably, the third pump laser 44 can provide pump excitation to the third gain fiber 42. Exemplarily, the output power of the third pump laser 44 is greater than 250W. Exemplarily, the center wavelength of the third pump laser 44 is 976nm. Exemplarily, the output fiber of the third pump laser 44 is a 135 / 155 multimode fiber.

[0070] Exemplarily, the signal fiber of the third combiner 43 can be 14 / 250 double-clad fiber. Exemplarily, the pump fiber of the third combiner 43 can be 135 / 155 multimode fiber. Exemplarily, the pump light coupling efficiency of the third combiner 43 is greater than 95%. Exemplarily, the signal light handling power of the third combiner 43 is greater than 300W. Exemplarily, the pump light handling power of the third combiner 43 is greater than 250W.

[0071] The fiber specifications of the third gain fiber 42 and the third combiner 43 can both be 14 / 250 fiber. The fiber specification of the main optical path of the third-stage amplification module 40 is 14 / 250 fiber, while the fiber specification of the output end of the second-stage amplification module 30 is 10 / 125 fiber. The specification of the output fiber of the second-stage amplification module 30 is different from that of the main optical path fiber of the third-stage amplification module 40. The second-stage amplification module 30 and the third-stage amplification module 40 use different specifications of fiber as the main optical path fiber to adapt to the specifications of their respective optical devices, but this results in mode field mismatch, which can easily affect optical signal transmission.

[0072] Please continue reading. Figure 5 In some embodiments, the input fiber of the mode field adapter 41 is a 10 / 125 single-clad fiber, consistent with the fiber specification of the output fiber of the secondary amplification module 30. Exemplarily, the output of the mode field adapter 41 can be a 14 / 250 double-clad fiber, with the fiber specification of the output fiber consistent with that of the third gain fiber 42. Exemplarily, the mode field adapter 41 can handle an average power greater than 20W.

[0073] The optical fiber at the input end of the mode field adapter 41 is connected to the optical fiber at the output end of the wavelength division multiplexer 32, and the optical fiber at the output end of the mode field adapter 41 is connected to the input end of the third gain optical fiber 42. This allows the second-stage amplification module 30 and the third-stage amplification module 40 to be connected. The mode field adapter 41 connects optical fibers of different specifications, which has little impact on the optical signal transmission, thus avoiding the impact on the optical signal transmission when the optical fiber specifications are different.

[0074] Therefore, the nanosecond pulsed fiber laser provided in this application embodiment can solve the technical problem in the related art where the main optical path fiber specifications are mismatched among multiple amplification modules, affecting the transmission of optical signals.

[0075] Please continue reading. Figure 1In some embodiments, the output isolator 50 operates at a wavelength of 1064 nm. Exemplarily, the input fiber of the output isolator 50 can be 14 / 250 double-clad fiber. Exemplarily, the output isolator 50 can handle an average power greater than 300 W. Exemplarily, the output isolator 50 can handle a peak power greater than 2 kW. Exemplarily, the isolation of the output isolator 50 is greater than 25 dB.

[0076] The specifications of the input optical fiber of the output isolator 50 are the same as those of the output optical fiber of the third combiner 43.

[0077] It should be noted that in this application, all devices and optical fibers are connected by using an optical fiber fusion splicer.

[0078] The nanosecond pulsed fiber laser provided in this application, achieved through reasonable output waveform design, appropriate optical path selection, and optimized gain allocation, possesses advantages such as compact optical path structure, simple structure, and uniform energy distribution of the output beam, making it an ideal laser source for laser marking and precision laser welding. The nanosecond pulsed fiber laser provided in this application can overcome problems such as severe nonlinear effects caused by excessively high output peak power and low reliability of fiber laser systems due to unreasonable fiber selection.

[0079] Specifically, the nanosecond pulsed fiber laser provided in this application uses 915nm and 976nm multimode semiconductor lasers as pump lasers. It utilizes a three-stage amplification structure to amplify the seed light power to an average power of 300W, a peak power greater than 2kW, and a single pulse energy greater than 0.2mJ, thereby achieving high repetition rate, high power, and high beam quality nanosecond pulsed laser output.

[0080] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

[0081] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A nanosecond pulsed fiber laser, characterized in that, include: Seed source module, the seed source module is used to output seed light; A primary amplification module, the input of which is connected to the seed source module; A secondary amplification module, wherein the input terminal of the secondary amplification module is connected to the output terminal of the primary amplification module; A three-stage amplification module, wherein the input terminal of the three-stage amplification module is connected to the output terminal of the two-stage amplification module; An output isolator, the input terminal of which is connected to the output terminal of the three-stage amplifier module; The output fiber of the seed source module has the same specifications as the fiber of the main optical path of the first-stage amplification module; the output fiber of the first-stage amplification module has the same specifications as the fiber of the main optical path of the second-stage amplification module; the output fiber of the second-stage amplification module has different specifications than the fiber of the main optical path of the third-stage amplification module, and the third-stage amplification module includes a mode field adapter.

2. The nanosecond pulsed fiber laser as described in claim 1, characterized in that, The seed source module includes a directly modulated semiconductor laser diode and a first in-line isolator. The output terminal of the semiconductor laser diode is connected to the input terminal of the first in-line isolator. The input terminal of the first-stage amplification module is connected to the output terminal of the first in-line isolator. The output terminal of the first in-line isolator is used to output the seed light.

3. The nanosecond pulsed fiber laser as described in claim 2, characterized in that, The center wavelength of the semiconductor laser diode is 1064nm, and / or the linewidth of the semiconductor laser diode is less than 15nm, and / or the output fiber of the semiconductor laser diode is Hi1060 fiber.

4. The nanosecond pulsed fiber laser as described in claim 2, characterized in that, The center wavelength of the first online isolator is 1059nm, and / or the operating bandwidth of the first online isolator is 16nm, and / or the input fiber of the first online isolator is Hi1060 fiber, and / or the output fiber of the first online isolator is 10 / 125 single-clad fiber.

5. The nanosecond pulsed fiber laser as described in claim 2, characterized in that, The first-stage amplification module further includes a first pump laser, a first photodetector, and a first beam combiner, a first gain fiber, a second in-line isolator, and a coupler connected in sequence. The input end of the first beam combiner is connected to the output end of the first in-line isolator, and the output end of the first pump laser is connected to the input end of the first beam combiner. The input end of the first beam combiner is used to receive the seed light and the pump light output by the first pump laser. The first output end of the coupler is connected to the input end of the second-stage amplification module, and the second output end of the coupler is connected to the first photodetector.

6. The nanosecond pulsed fiber laser as described in claim 5, characterized in that, The pump fiber and signal fiber of the first combiner are disposed at the input end of the first combiner. The output end of the first pump laser is connected to the pump fiber of the first combiner. The signal fiber of the first combiner is connected to the output end of the first in-line isolator. The signal fiber of the first combiner is a 10 / 125 double-clad fiber. The pump fiber of the first combiner is a 105 / 125 multimode fiber. And / or, the first gain fiber is a ytterbium-doped 10 / 125 double-clad fiber. And / or, the input fiber and output fiber of the second in-line isolator are both 10 / 125 single-clad fibers. And / or, the fiber at the input end, the fiber at the first output end, and the fiber at the second output end of the coupler are all 10 / 125 single-clad fibers.

7. The nanosecond pulsed fiber laser as described in claim 5, characterized in that, The secondary amplification module includes a red laser, a second pump laser, and a wavelength division multiplexer, a second gain fiber, a second beam combiner, and a third in-line isolator connected in sequence. The input of the wavelength division multiplexer is connected to the output of the primary amplification module, and the output of the red laser is connected to the input of the wavelength division multiplexer. The input of the wavelength division multiplexer is used to receive the optical signal output by the primary amplification module and the red light output by the red laser. The output of the second pump laser is connected to the output of the second beam combiner, and the input of the tertiary amplification module is connected to the output of the third in-line isolator.

8. The nanosecond pulsed fiber laser as described in claim 7, characterized in that, The wavelength division multiplexer (WDM) has a signal port and a red light port at its input. The signal port is connected to the output of the first-stage amplification module, and the red light port is connected to the output of the red laser. The optical fibers for the signal port and the output of the WDM are 10 / 125 single-clad fibers, and the optical fiber for the red light port is Hi1060 fiber. Alternatively, the second gain fiber is a ytterbium-doped 10 / 125 double-clad fiber. Or, the signal fiber of the second combiner is located at the input of the second combiner, and the pump fiber and output fiber of the second combiner are located at... At the output end of the second combiner, the output end of the second pump laser is connected to the pump fiber of the second combiner, the signal fiber of the second combiner is connected to the output end of the second gain fiber, and the output fiber of the second combiner is connected to the input end of the third in-line isolator. The signal fiber and output fiber of the second combiner are 10 / 125 double-clad fibers, and the pump fiber of the second combiner is a 105 / 125 multimode fiber; and / or, the input fiber of the third in-line isolator is a 10 / 125 single-clad fiber, and the output fiber of the second in-line isolator is a 10 / 125 single-clad fiber.

9. The nanosecond pulsed fiber laser as described in claim 1, characterized in that, The three-stage amplification module further includes a second photodetector and a mode field adapter, a third gain fiber, a third combiner, and a third pump laser connected in sequence. The input end of the mode field adapter is connected to the output end of the two-stage amplification module, the output end of the third pump laser is connected to the output end of the third combiner, and the output end of the third combiner is also connected to the input end of the output isolator. The second photodetector is located at the connection between the output end of the third combiner and the input end of the output isolator.

10. The nanosecond pulsed fiber laser as described in claim 9, characterized in that, The input fiber of the mode field adapter is a 10 / 125 single-clad fiber, and the output fiber of the mode field adapter is a 14 / 250 double-clad fiber; and / or, the third gain fiber is a ytterbium-doped 14 / 250 double-clad fiber; and / or, the signal fiber of the third combiner is located at the input of the third combiner, the pump fiber and the output fiber of the third combiner are located at the output of the third combiner, the output fiber of the third combiner is fused to the input of the output isolator, the second photodetector is located at the fusion point between the output fiber of the third combiner and the input of the output isolator, the output of the third pump laser is connected to the pump fiber of the third combiner, the signal fiber and the output fiber of the third combiner are 14 / 250 double-clad fibers, and the pump fiber of the third combiner is a 135 / 155 multimode fiber; and / or, the input fiber of the output isolator is a 135 / 155 multimode fiber.

Images