Nanosecond pulse fiber laser

Abstract

The utility model provides a nanosecond pulse fiber laser. The nanosecond pulse fiber laser comprises 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 is used for outputting seed light, the input end of the first-stage amplification module is connected with the seed source module, the input end of the second-stage amplification module is connected with the output end of the first-stage amplification module, the input end of the third-stage amplification module is connected with the output end of the second-stage amplification module, and the input end of the output isolator is connected with the output end of the third-stage amplification module. The first-stage amplification module is provided with a first photoelectric detector, the first photoelectric detector is used for detecting an optical signal output by the first-stage amplification module, and / or the third-stage amplification module is provided with a second photoelectric detector, and the second photoelectric detector is used for detecting an optical signal output by the third-stage amplification module. The nanosecond pulse fiber laser provided by the utility model is beneficial to improving the use performance.

Description

Technical Field

[0001] The present application belongs to the technical field of fiber lasers, and more specifically, relates to a nanosecond pulse fiber laser. Background Art

[0002] Nanosecond pulsed fiber lasers have been rapidly developing due to their excellent output beam quality, compact structure, and high flexibility. However, further improvements are needed to enhance their performance. Utility Model Content

[0003] The purpose of the embodiments of the present application is to provide a nanosecond pulse fiber laser to improve performance.

[0004] To achieve the above objectives, the technical solution adopted in this application is:

[0005] A nanosecond pulse 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 is configured to output seed light. The input end of the first-stage amplification module is connected to the seed source module, the input end of the second-stage amplification module is connected to the output end of the first-stage amplification module, the input end of the third-stage amplification module is connected to the output end of the second-stage amplification module, and the input end of the output isolator is connected to the output end of the third-stage amplification module. The first-stage amplification module is provided with a first photodetector configured to detect the optical signal output by the first-stage amplification module, and / or the third-stage amplification module is provided with a second photodetector configured to detect the optical signal output by the third-stage amplification module.

[0006] Through the above technical solution, the first-stage amplification module can amplify the seed light for the first time, the second-stage amplification module can amplify the seed light after the first amplification for the second time, and the third-stage amplification module can amplify the seed light after the second amplification for the third time, thereby amplifying the seed light three times to achieve the target performance index. In addition, the first photodetector can detect the optical signal output by the first-stage amplification module, and / or the second photodetector is used to detect the optical signal output by the third-stage amplification module. In this way, the optical path of the nanosecond pulse fiber laser can be detected, and the operating status of the nanosecond pulse fiber laser can be determined based on the detection results. The nanosecond pulse fiber laser can also be adjusted based on the detection results, which is beneficial to protecting the optical path system of the nanosecond pulse fiber laser and thus improving its performance.

[0007] In some embodiments, the seed source module includes a directly modulated semiconductor laser diode and a first online isolator, the output end of the semiconductor laser diode is connected to the input end of the first online isolator, the input end of the first-stage amplification module is connected to the output end of the first online isolator, and the output end of the first online isolator is used to output seed light.

[0008] In some embodiments, the first-stage amplification module includes a coupler, the input end of the coupler is used to receive the optical signal, 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.

[0009] In some embodiments, the splitting ratio of the coupler is 1:1000, and of the optical signal received by the coupler, 999‰ of the power is transmitted to the input end of the secondary amplification module, and 1‰ of the power is transmitted to the first photodetector.

[0010] In some embodiments, the first-stage amplification module further includes a first pump laser and a first beam combiner, a first gain fiber, and a second online isolator connected in sequence, the input end of the first beam combiner is connected to the seed source module, 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, and the output end of the second online isolator is connected to the input end of the coupler.

[0011] In some embodiments, the secondary amplification module includes a red light laser, a second pump laser, and a wavelength division multiplexer, a first mode field adapter, a second gain fiber, a second combiner, and a third online isolator connected in sequence. The input end of the wavelength division multiplexer is connected to the output end of the primary amplification module, the output end of the red light laser is connected to the input end of the wavelength division multiplexer, the input end 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 light laser, the output end of the second pump laser is connected to the output end of the second combiner, and the input end of the tertiary amplification module is connected to the output end of the third online isolator.

[0012] In some embodiments, the three-stage amplification module further includes a second mode field adapter, a third gain fiber, a third combiner, and a third pump laser connected in sequence, the input end of the second 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, the output end of the third combiner is also connected to the input end of the output isolator, and the second photodetector is arranged at the connection between the output end of the third combiner and the input end of the output isolator.

[0013] In some embodiments, the signal fiber of the third combiner is arranged at the input end of the third combiner, the pump fiber of the third combiner and the output fiber of the third combiner are arranged at the output end of the third combiner, the output fiber of the third combiner is fused with the input end of the output isolator, the second photodetector is arranged at the fusion point between the output fiber of the third combiner and the input end of the output isolator, and the output end of the third pump laser is connected to the pump fiber of the third combiner.

[0014] In some embodiments, the specifications of the output optical fiber of the seed source module are the same as the specifications of the optical fiber of the main optical path of the first-stage amplification module; and / or, the specifications of the output optical fiber of the first-stage amplification module are different from the specifications of the optical fiber of the main optical path of the second-stage amplification module; and / or, the specifications of the output optical fiber of the second-stage amplification module are different from the specifications of the optical fiber of the main optical path of the third-stage amplification module.

[0015] In some embodiments, the central wavelength of the semiconductor laser diode is 1064 nm, the linewidth of the semiconductor laser diode is less than 15 nm, and the output fiber of the semiconductor laser diode is a Hi1060 fiber; and / or the central wavelength of the first in-line isolator is 1059 nm, the operating bandwidth of the first in-line isolator is 16 nm, the input fiber of the first in-line isolator is a Hi1060 fiber, and the output fiber of the first in-line isolator is a 10 / 125 single-clad fiber. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0017] Figure 1 A schematic diagram of the structure of a nanosecond pulsed fiber laser provided in an embodiment of the present application;

[0018] Figure 2 A schematic diagram of the structure of the seed source module provided in an embodiment of the present application;

[0019] Figure 3 A schematic structural diagram of a first-stage amplification module provided in an embodiment of the present application;

[0020] Figure 4 A schematic structural diagram of a secondary amplification module provided in an embodiment of the present application;

[0021] Figure 5 This is a schematic structural diagram of the three-stage amplification module provided in an embodiment of the present application.

[0022] Among them, the reference numerals in the figures are:

[0023] 10-seed source module; 11-semiconductor laser diode; 12-first online isolator; 20-first stage amplification module; 21-first pump laser; 22-first combiner; 23-first gain fiber; 24-second online isolator; 25-coupler; 26-first photodetector; 30-second stage amplification module; 31-red laser; 32-wavelength division multiplexer; 33-first mode field adapter; 34-second gain fiber; 35-second combiner; 36-second pump laser; 37-third online isolator; 40-third stage amplification module; 41-second mode field adapter; 42-third gain fiber; 43-third combiner; 44-third pump laser; 45-second photodetector; 50-output isolator. DETAILED DESCRIPTION

[0024] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0025] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0026] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and 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, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0027] 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 the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0028] Nanosecond pulsed fiber lasers have been rapidly developing due to their advantages, such as excellent output beam quality, compact structure, and high flexibility. Related art nanosecond pulsed fiber lasers utilize Q-switching technology (Q-switching) and semiconductor laser diodes to generate seed light, which is then amplified by an amplifier module to achieve the target performance indicators. However, these related art nanosecond pulsed fiber lasers require further improvements to enhance their performance.

[0029] For example, nanosecond pulse fiber lasers in related technologies use master oscillator power amplifier (MOPA) technology to amplify seed light. This utilizes multiple sequentially connected amplifier modules to amplify the seed light, resulting in a long optical path. This prevents effective detection of the optical signal during transmission, making it difficult to determine the operating status of the nanosecond pulse fiber laser.

[0030] Please also refer to Figures 1 to 5 , the nanosecond pulse fiber laser provided in the embodiments of the present application is now described.

[0031] See also Figure 1 The nanosecond pulse fiber laser provided in the embodiment of the present application 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 can output seed light, the input end of the first-stage amplification module 20 is connected to the seed source module 10, the first-stage amplification module 20 can amplify the seed light for the first time, the input end of the second-stage amplification module 30 is connected to the output end of the first-stage amplification module 20, the second-stage amplification module 30 can amplify the seed light after the first amplification for the second time, the input end of the third-stage amplification module 40 is connected to the output end of the second-stage amplification module 30, the third-stage amplification module 40 can amplify the seed light after the second amplification for the third time, the input end of the output isolator 50 is connected to the output end of the third-stage amplification module 40, and the output isolator 50 is used to output the amplified seed light.

[0032] See also Figure 2 In some embodiments, the seed source module 10 includes a directly modulated semiconductor laser diode 11 and a first online isolator 12. The output end of the semiconductor laser diode 11 is connected to the input end of the first online isolator 12. The input end of the first-stage amplification module 20 is connected to the output end of the first online isolator 12. The output end of the first online isolator 12 is used to output seed light.

[0033] Among them, the semiconductor laser diode 11 can be directly modulated to achieve a more flexible frequency tuning range, and the pulse width is tunable, and the corresponding optical signal can be output according to demand, thereby meeting the diversified application market needs.

[0034] Exemplarily, the semiconductor laser diode 11 can be a commercial superluminescent diode (SLD), which has the advantages of high power, wide spectrum, small ripple, and good temperature stability. Exemplarily, the center wavelength of the semiconductor laser diode 11 can be 1064nm. Exemplarily, the line width of the semiconductor laser diode 11 is less than 15nm. Exemplarily, the output fiber of the semiconductor laser diode 11 is a Hi1060 fiber. Exemplarily, the output state of the semiconductor laser diode 11 is pulsed. Exemplarily, the pulse width range of the semiconductor laser diode 11 can be 10ns-400ns, which can have a wide tuning range. Exemplarily, the pulse width range of the semiconductor laser diode 11 can also be 40ns-400ns, which can have a wide tuning range. Exemplarily, the repetition frequency of the semiconductor laser diode 11 can be 1kHz-4000kHz.

[0035] Exemplarily, the central wavelength of the first in-line isolator 12 can be 1059 nm. Exemplarily, the operating bandwidth of the first in-line isolator 12 can be 16 nm. Exemplarily, the input optical fiber of the first in-line isolator 12 can be Hi1060 optical fiber. Exemplarily, the output optical fiber of the first in-line isolator 12 can be 10 / 125 single-clad optical fiber. In addition, the optical fiber of the main optical path of the first-stage amplification module 20 is a 10 / 125 optical fiber. In this way, the specifications of the output optical fiber of the seed source module 10 are the same as the specifications of the optical fiber of the main optical path of the first-stage amplification module 20, which facilitates the connection between the seed source module 10 and the first-stage amplification module 20.

[0036] Exemplarily, the first in-line isolator 12 can withstand an average power of 300 mW. The average power withstand of the first in-line isolator 12 is greater than the output power of the semiconductor laser diode 11, and the average power withstand of the first in-line isolator 12 can match that of the semiconductor laser diode 11. Exemplarily, the insertion loss of the first in-line isolator 12 is less than 3 dB. Exemplarily, the isolation of the first in-line isolator 12 is greater than 25 dB.

[0037] See also Figure 3 In some embodiments, the primary amplification module 20 is provided with a first photodetector 26, which is used to detect the optical signal output by the primary amplification module 20. Thus, the first photodetector 26 can detect the optical path of the nanosecond pulse fiber laser, thereby determining the operating status of the nanosecond pulse fiber laser based on the detection results. The nanosecond pulse fiber laser can also be adjusted based on the detection results, which helps protect the optical path system of the nanosecond pulse fiber laser and thus improves its performance.

[0038] For example, the nanosecond pulse fiber laser provided in the embodiment of the present application may also include a controller, which is electrically connected to the first photodetector 26. The first photodetector 26 may also be electrically connected to the seed source module 10. The controller can obtain information detected by the first photodetector 26, so that the seed source module 10 can be controlled according to the information detected by the first photodetector 26, thereby adjusting the nanosecond pulse fiber laser.

[0039] Exemplarily, the first photodetector 26 is a commercial fiber-coupled photodetector, and the optical fiber of the first photodetector 26 may be a Hi1060 optical fiber.

[0040] Please continue reading Figure 3 In some embodiments, the first-stage amplification module 20 further includes a coupler 25. The input end of the coupler 25 is used to receive an optical signal. The first output end of the coupler 25 is connected to the input end of the second-stage amplification module 30. The second output end of the coupler 25 is connected to the first photodetector 26. In this way, the first photodetector 26 can receive the optical signal from the coupler 25, thereby detecting the operating status of the optical path of the nanosecond pulse fiber laser.

[0041] For example, the splitting ratio of coupler 25 can be 1:1000, or in other words, the coupling ratio of coupler 25 is 999:1. Thus, of the optical signal received by coupler 25, 999‰ of the power is transmitted to the input of secondary amplification module 30, and 1‰ of the power is transmitted to first photodetector 26. The first photodetector 26 can detect the operating status of the optical path of the nanosecond pulse fiber laser using this smaller power ratio.

[0042] For example, the coupler 25 may be able to withstand an average power of 2 W and may be used in the first-stage amplification module 20 .

[0043] Exemplarily, the optical fiber at the input end of the coupler 25 can be a 10 / 125 single-clad optical fiber. Exemplarily, the optical fiber at the first output end of the coupler 25 can be a 10 / 125 single-clad optical fiber. Exemplarily, the optical fiber at the second output end of the coupler 25 can be a 10 / 125 single-clad optical fiber.

[0044] Please continue reading Figure 3In some embodiments, the first-stage amplification module 20 further includes a first pump laser 21 and a first combiner 22, a first gain fiber 23, and a second online isolator 24 connected in sequence. The input end of the first 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 combiner 22. The input end of the first 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 online isolator 24 is connected to the input end of the coupler 25. The first output end of the coupler 25 forms the output end of the first-stage amplification module 20.

[0045] The output power of the first pump laser 21 is greater than 10 W, the central wavelength of the first pump laser 21 is 915 nm, and the output fiber of the first pump laser 21 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 an ytterbium-doped fiber. Exemplarily, the first gain fiber 23 is an ytterbium-doped 10 / 125 double-clad fiber.

[0046] Exemplarily, 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. Exemplarily, 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 tolerance is greater than 1W, and the pump light power tolerance is greater than 10W.

[0047] For example, the input fiber of the second inline isolator 24 can be a 10 / 125 single-clad fiber. For example, the output fiber of the second inline 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 facilitates optical signal transmission.

[0048] Exemplarily, the center wavelength of the second in-line isolator 24 is 1062 nm. Exemplarily, the operating bandwidth of the second in-line isolator 24 is 20 nm. Exemplarily, the average power withstand of the second in-line isolator 24 is 2 W. Exemplarily, the insertion loss of the second in-line isolator 24 is less than 1.5 dB. Exemplarily, the isolation of the second in-line isolator 24 is greater than 25 dB.

[0049] See also Figure 4In some embodiments, the secondary amplification module 30 includes a red laser 31, a second pump laser 36, and a wavelength division multiplexer 32, a first mode field adapter 33, a second gain fiber 34, a second combiner 35 and a third online isolator 37 connected in sequence.

[0050] Among them, the input end of the wavelength division multiplexer 32 is connected to the output end of the first-stage amplification module 20, the output end of the red light laser 31 is connected to the input end of the wavelength division multiplexer 32, the input end of the wavelength division multiplexer 32 is used to receive the optical signal output by the first-stage amplification module 20 and the red light output by the red light laser 31, the output end of the second pump laser 36 is connected to the output end of the second combiner 35, and the input end of the third-stage amplification module 40 is connected to the output end of the third online isolator 37.

[0051] Exemplarily, the red laser is a commercial red laser diode. Exemplarily, the output fiber of the red laser 31 is a Hi1060 fiber, and the output power of the red laser 31 is greater than 60 mW.

[0052] In some embodiments, the input end 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 end of the first-stage amplifier module 20 (the first output end of the coupler 25), and the red light port of the wavelength division multiplexer 32 is connected to the output end of the red light laser 31 (the output optical fiber of the red light laser 31). The optical fiber of the signal port is a 10 / 125 single-clad optical fiber, and the optical fiber of the red light port is a Hi1060 optical fiber. The optical fiber of the signal port of the wavelength division multiplexer 32 and the optical fiber of the first output end of the coupler 25 have the same specifications and can be directly connected. The optical fiber of the red light port of the wavelength division multiplexer 32 and the optical fiber of the output optical fiber of the red light laser 31 have the same specifications 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 light laser 31.

[0053] Exemplarily, the wavelength division multiplexer can withstand an average power greater than 2W.

[0054] For example, the second gain fiber 34 may be an ytterbium-doped fiber. For example, the second gain fiber 34 may be an ytterbium-doped 20 / 125 double-clad fiber.

[0055] It will be appreciated that the second pump laser 36 can provide pump excitation for the second gain fiber 34. Exemplarily, the output power of the second pump laser 36 is greater than 30 W. Exemplarily, the output power of the second pump laser 36 is greater than 50 W. Exemplarily, the central wavelength of the second pump laser 36 is 915 nm. Exemplarily, the output fiber of the second pump laser 36 is a 105 / 125 multimode fiber.

[0056] Exemplarily, the signal fiber of the second combiner 35 is arranged at the input end of the second combiner 35, the pump fiber and the output fiber of the second combiner 35 are arranged at the output end of the second combiner 35, the output end of the second pump laser 36 is connected to the pump fiber of the second combiner 35, the signal fiber of the second combiner 35 is connected to the output end of the second gain fiber 34, the output fiber of the second combiner 35 is connected to the input end of the third online isolator 37, and the output end of the third online isolator 37 forms the output end of the secondary amplification module 30.

[0057] The signal fiber of the second combiner 35 can be a 20 / 125 double-clad fiber, the output fiber of the second combiner 35 can be a 20 / 125 double-clad fiber, and the pump fiber of the second combiner 35 can be a 105 / 125 multimode fiber. Exemplarily, the pump light coupling efficiency of the second combiner 35 is greater than 95%. Exemplarily, the signal light power of the second combiner 35 can withstand greater than 10W. Exemplarily, the signal light power of the second combiner 35 can withstand greater than 20W. Exemplarily, the pump light power of the second combiner 35 can withstand greater than 30W. Exemplarily, the pump light power of the second combiner 35 can withstand greater than 50W.

[0058] Exemplarily, the input fiber of the third in-line isolator 37 is a 20 / 125 single-clad fiber. Exemplarily, the output fiber of the second in-line isolator 24 is a 20 / 125 single-clad fiber. Exemplarily, the center wavelength of the third in-line isolator 37 is 1062 nm. Exemplarily, the operating bandwidth of the third in-line isolator 37 is 20 nm. Exemplarily, the average power withstand of the third in-line isolator 37 is 10 W. Exemplarily, the average power withstand of the third in-line isolator 37 is 20 W. Exemplarily, the insertion loss of the third in-line isolator 37 is less than 1 dB. Exemplarily, the isolation of the third in-line isolator 37 is greater than 25 dB.

[0059] It is understood that the 20 / 125 fiber specifications used to transmit optical signals in the main optical path of the secondary amplifier module 30, which are used by the second gain fiber 34, the second combiner 35, and the third in-line isolator 37, can be directly connected. Therefore, the fiber specifications of the main optical path of the secondary amplifier module 30 are 20 / 125 fiber. The optical fiber at the output end of the primary amplifier module 20 and the optical fiber at the output end of the wavelength division multiplexer 32 are 10 / 125 single-clad fiber. The specifications of the output fiber of the primary amplifier module 20 are different from those of the main optical path of the secondary amplifier module 30. The primary amplifier module 20 and the secondary amplifier module 30 use optical fibers of different specifications as the optical fibers for the main optical path to accommodate the specifications of their respective optical devices, but there is a mode field mismatch, which can easily affect optical signal transmission.

[0060] Please continue reading Figure 4In some embodiments, the optical fiber at the input end of the first mode field adapter 33 is a 10 / 125 single-clad optical fiber, which has the same specifications as the optical fiber at the output end of the wavelength division multiplexer 32. The optical fiber at the output end of the first mode field adapter 33 is a 20 / 130 single-clad optical fiber, which has the same specifications as the second gain fiber 34. Exemplarily, the first mode field adapter 33 can withstand an average power greater than 2W.

[0061] The optical fiber at the input end of the first mode field adapter 33 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 first mode field adapter 33 is connected to the input end of the second gain fiber 34, so that the first-stage amplification module 20 and the second-stage amplification module 30 can be connected through the wavelength division multiplexer 32 and the first mode field adapter 33 without affecting the transmission of optical signals.

[0062] See also Figure 5 In some embodiments, the three-stage amplification module 40 is provided with a second photodetector 45, which is used to detect the optical signal output by the three-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 status of the nanosecond pulse fiber laser based on the detection results. The nanosecond pulse fiber laser can also be adjusted based on the detection results, which is beneficial for protecting the optical path system of the nanosecond pulse fiber laser and thus improving its performance.

[0063] For example, the controller can be electrically connected to the second photodetector 45, and the second photodetector 45 can also be electrically connected to the seed source module 10. The controller can obtain the information detected by the second photodetector 45, so that the seed source module 10 can be controlled according to the information detected by the second photodetector 45, thereby adjusting the nanosecond pulse fiber laser.

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

[0065] In some embodiments, the three-stage amplification module 40 also includes a second 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 second 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, and the output end of the third combiner 43 is also connected to the input end of the output isolator 50. The second photodetector 45 is arranged at the connection between the output end of the third combiner 43 and the input end of the output isolator 50.

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

[0067] Exemplarily, the second photodetector 45 is disposed above a fusion point between the output optical fiber of the third combiner 43 and the input end of the output isolator 50 .

[0068] For example, the third gain fiber 42 may be an ytterbium-doped fiber. For example, the third gain fiber 42 may be an ytterbium-doped 50 / 400 double-clad fiber. For example, the third gain fiber 42 may be an ytterbium-doped 30 / 600 double-clad fiber.

[0069] It is understood that 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 150 W. Exemplarily, the central wavelength of the third pump laser 44 is 915 nm. Exemplarily, the output fiber of the third pump laser 44 is a 105 / 125 multimode fiber.

[0070] Exemplarily, the output power of the third pump laser 44 is greater than 450 W. Exemplarily, the central wavelength of the third pump laser 44 is 976 nm. Exemplarily, the output fiber of the third pump laser 44 is a 200 / 220 multimode fiber.

[0071] Exemplarily, the signal fiber of the third combiner 43 can be a 50 / 400 double-clad fiber. Exemplarily, the signal fiber of the third combiner 43 can be a 30 / 600 double-clad fiber. Exemplarily, the pump fiber of the third combiner 43 can be a 105 / 125 multimode fiber. Exemplarily, the pump fiber of the third combiner 43 can be a 200 / 220 multimode fiber. Exemplarily, the pump light coupling efficiency of the third combiner 43 is greater than 95%. Exemplarily, the signal light power of the third combiner 43 can withstand greater than 70W. Exemplarily, the pump light power of the third combiner 43 can withstand greater than 150W.

[0072] The fiber specifications of the third gain fiber 42 and the third combiner 43 can both be 50 / 400 fiber, or 30 / 600 fiber. The fiber specifications of the main optical path of the three-stage amplification module 40 are 50 / 400 fiber or 30 / 600 fiber, while the fiber specifications of the output end of the secondary amplification module 30 are 20 / 125 fiber. The specifications of the output fiber of the secondary amplification module 30 differ from those of the main optical path of the three-stage amplification module 40. The secondary amplification module 30 and the three-stage amplification module 40 use different optical fibers for their main optical paths to accommodate the specifications of their respective optical components, but this makes connection inconvenient and can easily affect optical signal transmission.

[0073] Please continue reading Figure 5 In some embodiments, the optical fiber at the input end of the second mode field adapter 41 is a 20 / 125 single-clad optical fiber, which has the same specifications as the optical fiber at the output end of the secondary amplification module 30. For example, the output end of the second mode field adapter 41 can be a 50 / 400 double-clad optical fiber or a 30 / 600 double-clad optical fiber. The optical fiber specifications at the output end of the second mode field adapter 41 are consistent with those of the third gain fiber 42. For example, the second mode field adapter 41 can withstand an average power greater than 10 W.

[0074] The optical fiber at the input end of the second 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 second mode field adapter 41 is connected to the input end of the third gain fiber 42, so that the secondary amplification module 30 and the tertiary amplification module 40 can be connected without affecting the transmission of optical signals.

[0075] Please continue reading Figure 1 In some embodiments, the operating wavelength of the output isolator 50 is 1064 nm. Exemplarily, the input fiber of the output isolator 50 can be a 50 / 400 double-clad fiber. Exemplarily, the input fiber of the output isolator 50 can be a 30 / 600 double-clad fiber. Exemplarily, the output isolator 50 can withstand an average power greater than 70 W. Exemplarily, the output isolator 50 can withstand an average power greater than 500 W. Exemplarily, the output isolator 50 can withstand a peak power greater than 20 kW. Exemplarily, the output isolator 50 has an isolation greater than 25 dB.

[0076] The specifications of the input optical fiber of the output isolator 50 are consistent with the specifications of the optical fiber at the output end of the third combiner 43 .

[0077] In some embodiments, the nanosecond pulse fiber laser provided in the embodiments of the present application further includes an output collimator, which is connected to the input optical fiber of the output isolator 50, or the output collimator is connected to the output optical fiber of the output isolator 50. The operating wavelength of the output collimator is consistent with the operating wavelength of the output isolator 50, the optical fiber specifications of the output collimator are consistent with the optical fiber specifications of the output isolator 50, the average power withstand of the output collimator is consistent with the average power withstand of the output isolator 50, and the peak power withstand of the output collimator is consistent with the peak power withstand of the output isolator 50.

[0078] In some embodiments, the output isolator 50 can be replaced with an output collimator.

[0079] It should be noted that, in the present application, the connections between various devices and optical fibers are all fusion-spliced ​​using an optical fiber fusion splicer.

[0080] The nanosecond pulse fiber laser provided in the embodiments of this application, achieved through a rationally designed output waveform, appropriate optical path selection, and optimized gain distribution, has the advantages of a compact optical path structure, a simple structure, and uniform output spot energy distribution, making it an ideal laser light source for laser marking and laser precision welding. The nanosecond pulse fiber laser provided in the embodiments of this application can overcome problems such as severe nonlinear effects caused by excessively high output peak power and low reliability of fiber laser systems caused by improper fiber selection.

[0081] Specifically, the nanosecond pulse fiber laser provided in the embodiment of the present application uses a 915nm multimode semiconductor laser as a pump laser, and utilizes a three-stage amplification structure to amplify the seed light power to 70W average power, greater than 20kW peak power, and greater than 1.4mJ single pulse energy, thereby achieving nanosecond pulse laser output with high energy, high power, and uniform output spot energy distribution.

[0082] The nanosecond pulse fiber laser provided in the embodiment of the present application can also use a 976nm multimode semiconductor laser as a pump laser, and utilize a three-stage amplification structure to amplify the seed light power to an average power of 500W, a peak power greater than 10kW, and a single pulse energy greater than 1.8mJ, thereby achieving nanosecond pulse laser output with high energy, high power, and uniform output spot energy distribution.

[0083] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A nanosecond pulse fiber laser, characterized in that: include: A seed source module, the seed source module is used to output seed light; a first-stage amplification module, wherein an input end of the first-stage amplification module is connected to the seed source module; a secondary amplification module, wherein the input end of the secondary amplification module is connected to the output end of the primary amplification module; A three-stage amplification module, wherein the input end of the three-stage amplification module is connected to the output end of the two-stage amplification module; an output isolator, wherein the input end of the output isolator is connected to the output end of the three-stage amplification module; The first-stage amplification module is provided with a first photodetector, which is used to detect the optical signal output by the first-stage amplification module, and / or the third-stage amplification module is provided with a second photodetector, which is used to detect the optical signal output by the third-stage amplification module.

2. The nanosecond pulse fiber laser according to claim 1, wherein The seed source module includes a directly modulated semiconductor laser diode and a first online isolator. The output end of the semiconductor laser diode is connected to the input end of the first online isolator. The input end of the first-stage amplification module is connected to the output end of the first online isolator. The output end of the first online isolator is used to output the seed light.

3. The nanosecond pulse fiber laser according to claim 1, wherein The first-stage amplification module includes a coupler, an input end of the coupler is used to receive an optical signal, a first output end of the coupler is connected to the input end of the second-stage amplification module, and a second output end of the coupler is connected to the first photodetector.

4. The nanosecond pulse fiber laser according to claim 3, wherein: The splitting ratio of the coupler is 1:1000. Among the optical signals received by the coupler, 999‰ of the power is transmitted to the input end of the secondary amplification module, and 1‰ of the power is transmitted to the first photodetector.

5. The nanosecond pulse fiber laser according to claim 3, wherein: The first-stage amplification module also includes a first pump laser and a first beam combiner, a first gain fiber, and a second online isolator connected in sequence. The input end of the first beam combiner is connected to the seed source module, 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, and the output end of the second online isolator is connected to the input end of the coupler.

6. The nanosecond pulse fiber laser according to claim 1, wherein: The secondary amplification module includes a red light laser, a second pump laser, and a wavelength division multiplexer, a first mode field adapter, a second gain fiber, a second combiner, and a third online isolator connected in sequence. The input end of the wavelength division multiplexer is connected to the output end of the primary amplification module, the output end of the red light laser is connected to the input end of the wavelength division multiplexer, the input end 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 light laser, the output end of the second pump laser is connected to the output end of the second combiner, and the input end of the tertiary amplification module is connected to the output end of the third online isolator.

7. The nanosecond pulse fiber laser according to claim 1, wherein: The three-stage amplification module also includes a second mode field adapter, a third gain fiber, a third combiner and a third pump laser connected in sequence. The input end of the second 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 arranged at the connection between the output end of the third combiner and the input end of the output isolator.

8. The nanosecond pulse fiber laser according to claim 7, wherein: The signal fiber of the third combiner is arranged at the input end of the third combiner, the pump fiber of the third combiner and the output fiber of the third combiner are arranged at the output end of the third combiner, the output fiber of the third combiner is fused with the input end of the output isolator, the second photodetector is arranged at the fusion point between the output fiber of the third combiner and the input end of the output isolator, and the output end of the third pump laser is connected to the pump fiber of the third combiner.

9. The nanosecond pulse fiber laser according to any one of claims 1 to 8, characterized in that: The specifications of the output optical fiber of the seed source module are the same as the specifications of the optical fiber of the main optical path of the first-stage amplification module; and / or, the specifications of the output optical fiber of the first-stage amplification module are different from the specifications of the optical fiber of the main optical path of the second-stage amplification module; and / or, the specifications of the output optical fiber of the second-stage amplification module are different from the specifications of the optical fiber of the main optical path of the third-stage amplification module.

10. The nanosecond pulse fiber laser according to claim 2, wherein: The center wavelength of the semiconductor laser diode is 1064 nm, the linewidth of the semiconductor laser diode is less than 15 nm, and the output fiber of the semiconductor laser diode is Hi1060 fiber; and / or the center wavelength of the first in-line isolator is 1059 nm, the operating bandwidth of the first in-line isolator is 16 nm, the input fiber of the first in-line isolator is Hi1060 fiber, and the output fiber of the first in-line isolator is 10 / 125 single-clad fiber.

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