Nanosecond pulsed fiber laser

Abstract

The present application provides a nanosecond pulse fiber laser, which includes a laser seed source and at least one amplification component, wherein the laser seed source is a directly modulated semiconductor laser diode, the central wavelength is 1064nm, and the output state is pulsed; the amplification component includes a pump laser and an ytterbium-doped double-clad fiber, the central wavelength of the pump laser is 915±5nm, the laser seed source is connected to the ytterbium-doped double-clad fiber, and the pump laser is connected to the ytterbium-doped double-clad fiber. The nanosecond pulse fiber laser can achieve a large frequency tuning range and tunable pulse width, so that it can meet the needs of the laser processing field with higher flexibility in parameter adjustment.

Description

Technical Field

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

[0002] Nanosecond pulse fiber lasers have excellent output beam quality, compact structure, high flexibility, high reliability, and maintenance-free advantages, so they are developing rapidly. The current nanosecond pulse fiber lasers have insufficient flexibility in output pulse width tuning. Summary of the invention

[0003] The purpose of the embodiments of the present application is to provide a nanosecond pulse fiber laser to solve the technical problem of insufficient flexibility in output pulse width tuning of nanosecond pulse fiber lasers in the prior art.

[0004] To achieve the above purpose, the technical solution adopted in this application is: to provide a nanosecond pulse fiber laser, the nanosecond pulse fiber laser comprising:

[0005] Laser seed source; the laser seed source is a directly modulated semiconductor laser diode with a central wavelength of 1064nm and a pulse output state;

[0006] At least one amplification component; the amplification component includes a pump laser and an ytterbium-doped double-clad optical fiber, the central wavelength of the pump laser is 915±5nm, the laser seed source is connected to the ytterbium-doped double-clad optical fiber, and the pump laser is connected to the ytterbium-doped double-clad optical fiber.

[0007] Optionally, the directly modulated semiconductor laser diode is an SLD semiconductor laser diode, the line width of the SLD semiconductor laser diode is less than 15 nm, the output optical fiber is a Hi1060 optical fiber, the pulse width range is 5-500 ns, and the repetition frequency is 1-4500 kHz.

[0008] Optionally, the nanosecond pulse fiber laser also includes a first online isolator, which is connected between the laser seed source and the amplification component. The first online isolator has a central wavelength of 1059nm, an operating bandwidth of 16nm, an input optical fiber of Hi1060 optical fiber, an output optical fiber of 10 / 125 single-clad optical fiber, an average power of 300mW, an insertion loss of less than 3dB, and an isolation greater than 25dB.

[0009] Optionally, the amplification component includes a first-stage amplification component, which includes a first pump laser, a first ytterbium-doped double-clad optical fiber and a first beam combiner;

[0010] The signal end of the first beam combiner is connected to the laser seed source, the pump end of the first beam combiner is connected to the first pump laser, and the output end of the first beam combiner is connected to the first ytterbium-doped double-clad optical fiber, so that the first pump laser provides pump excitation to the first ytterbium-doped double-clad optical fiber;

[0011] The output power of the first pump laser is greater than 10W, the central wavelength is 915nm±5nm, and the output optical fiber is a 105 / 125 multimode optical fiber; the first ytterbium-doped double-clad optical fiber is an ytterbium-doped 10 / 125 double-clad optical fiber; the optical fiber at the signal end of the first combiner is a 10 / 125 double-clad optical fiber, and the optical fiber at the pump end is a 105 / 125 multimode optical fiber, the pump light coupling efficiency is greater than 95%, the signal light withstand power is greater than 2W, and the pump light withstand power is greater than 10W.

[0012] Optionally, the amplification component includes a secondary amplification component, which includes a second pump laser, a second ytterbium-doped double-clad optical fiber, and a second combiner;

[0013] The second ytterbium-doped double-clad optical fiber is connected to the first-stage amplification component, the pump end of the second beam combiner is connected to the second pump laser, and the output end of the second beam combiner is connected to the second ytterbium-doped double-clad optical fiber, so that the second pump laser provides pump excitation to the second ytterbium-doped double-clad optical fiber, and the signal end of the second beam combiner serves as the output end of the second-stage amplification component;

[0014] The output power of the second pump laser is greater than 30W, the central wavelength is 915nm±5nm, and the output optical fiber is 105 / 125 multimode optical fiber; the second ytterbium-doped double-clad optical fiber is ytterbium-doped 10 / 125 double-clad optical fiber; the optical fiber at the signal end of the second combiner is 10 / 125 double-clad optical fiber, and the optical fiber at the pump end is 105 / 125 multimode optical fiber, the pump light coupling efficiency is greater than 95%, the signal light withstand power is greater than 10W, and the pump light withstand power is greater than 30W.

[0015] Optionally, the nanosecond pulse fiber laser further comprises a second online isolator, the second online isolator being connected between the first ytterbium-doped double-clad fiber and the second ytterbium-doped double-clad fiber;

[0016] The central wavelength of the second online isolator is 1062nm, the working bandwidth is 20nm, the input fiber is 10 / 125 single-clad fiber, the output fiber is 10 / 125 single-clad fiber, the average power is 2W, the insertion loss is less than 1.5dB, and the isolation is greater than 25dB.

[0017] Optionally, the amplification component includes a three-stage amplification component, and the second-stage amplification component includes a third pump laser, a third ytterbium-doped double-clad optical fiber, and a third beam combiner;

[0018] The third ytterbium-doped double-clad optical fiber is connected to the secondary amplification component, the pump end of the third beam combiner is connected to the third pump laser, and the output end of the third beam combiner is connected to the third ytterbium-doped double-clad optical fiber, so that the third pump laser provides pump excitation to the third ytterbium-doped double-clad optical fiber, and the signal end of the third beam combiner serves as the output end of the three-stage amplification component;

[0019] The output power of the third pump laser is greater than 200W, the central wavelength is 915nm±5nm, and the output fiber is 135 / 155 multimode fiber; the third ytterbium-doped double-clad fiber is ytterbium-doped 30 / 250 double-clad fiber; the fiber at the signal end of the third combiner is 30 / 250 double-clad fiber, and the fiber at the pump end is 135 / 155 multimode fiber, the pump light coupling efficiency is greater than 95%, the signal light withstand power is greater than 100W, and the single-arm pump light withstand power is greater than 200W.

[0020] Optionally, the nanosecond pulse fiber laser further comprises a third online isolator, which is connected between the second ytterbium-doped double-clad fiber and the third ytterbium-doped double-clad fiber;

[0021] The central wavelength of the third online isolator is 1062nm, the working bandwidth is 20nm, the input fiber is 10 / 125 double-clad fiber, the output fiber is 10 / 125 double-clad fiber, the average power is 10W, the insertion loss is less than 1dB, and the isolation is greater than 25dB.

[0022] Optionally, the nanosecond pulse fiber laser also includes a mode field adapter, which is connected between the third online isolator and the three-stage amplification component. The input end of the mode field adapter is a 10 / 125 double-clad optical fiber, and the output end is a 30 / 250 double-clad optical fiber, which can withstand an average power greater than 10W.

[0023] Optionally, the nanosecond pulse fiber laser also includes an output isolator, which is arranged at the output end of the three-stage amplification component. The working wavelength of the output isolator is 1064nm, the input optical fiber is 30 / 250 double-clad optical fiber, and can withstand an average power greater than 100W, a peak power greater than 20kW, and an isolation greater than 25dB.

[0024] The beneficial effect of the nanosecond pulse fiber laser provided by the present application is that, compared with the prior art, the nanosecond pulse fiber laser of the present application adopts a directly modulated semiconductor laser diode as a seed source, and combines a pump laser with a central wavelength of 915±5nm and an ytterbium-doped double-clad optical fiber for amplification, which can achieve a very large frequency tuning range and tunable pulse width, so that it can meet the needs of the laser processing field for higher flexibility in parameter adjustment. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 paying creative labor.

[0026] Figure 1 Schematic diagram of a nanosecond pulse fiber laser in an embodiment of the present application.

[0027] Among them, the reference numerals in the figure are:

[0028] Seed source component 1; SLD semiconductor laser diode 11; first online isolator 12; first-stage amplification component 2; first pump laser 21; first combiner 22; first ytterbium-doped double-clad fiber 23; second online isolator 24; second-stage amplification component 3; second ytterbium-doped double-clad fiber 31; second combiner 32; second pump laser 33; third online isolator 34; third-stage amplification component 4; mode field adapter 41; third ytterbium-doped double-clad fiber 42; third combiner 43; third pump laser 44, output isolator 51. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0030] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can 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 can be directly connected to the other element or indirectly connected to the other element.

[0031] 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 drawings, and are only for the convenience of describing the present 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 should not be understood as a limitation on the present application.

[0032] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0033] Nanosecond pulse fiber lasers have excellent output beam quality, compact structure, high flexibility, high reliability, and maintenance-free advantages, so they are developing rapidly. At present, the main methods for generating nanosecond pulse fiber lasers are Q-switching technology, direct modulation of semiconductor laser diodes, and MOPA technology based on several stages of fiber amplifiers to achieve the target performance indicators.

[0034] The nanosecond pulse laser produced by combining Q-switching technology with MOPA technology has disadvantages such as single output pulse width and limited tuning frequency range, and cannot meet the needs of diversified application markets.

[0035] See also Figure 1 Now, the nanosecond pulse fiber laser provided in the embodiment of the present application is described. The nanosecond pulse fiber laser includes:

[0036] Laser seed source; the laser seed source is a directly modulated semiconductor laser diode, the central wavelength of the laser seed source is 1064nm, and the output state is pulse;

[0037] At least one amplification component 2; the amplification component includes a pump laser and an ytterbium-doped double-clad optical fiber, the central wavelength of the pump laser is 915±5nm, the laser seed source is connected to the ytterbium-doped double-clad optical fiber, and the pump laser is connected to the ytterbium-doped double-clad optical fiber.

[0038] The laser seed source of this embodiment is a directly modulated semiconductor laser diode, which is a laser that adjusts the laser output intensity and frequency by directly changing its injection current. The central wavelength of the directly modulated semiconductor laser diode is 1064nm. Lasers of this wavelength are easily absorbed by a variety of materials such as metals, plastics, and ceramics, and are suitable for laser processing of a variety of materials. Pulsed lasers have the characteristics of high peak power and short duration, and are suitable for laser processing scenarios that require high precision and high energy density. The nanosecond pulse fiber laser of this embodiment has one or more stages of amplification components. The amplification component includes a pump laser and an ytterbium-doped double-clad fiber. The pump laser provides energy to excite the ytterbium ions in the ytterbium-doped double-clad fiber. The ytterbium ions in the ytterbium-doped double-clad fiber absorb the energy of the pump light and transition from the ground state to the excited state. Through continuous pumping, the number of excited state particles of the ytterbium ions exceeds the number of ground state particles, forming a population inversion. Under the condition of population inversion, when the laser photons of the laser seed source pass through the fiber, more ytterbium ions can be stimulated to transition from the excited state back to the ground state, and at the same time, photons with the same frequency and phase as the laser photons of the laser seed source are released, realizing stimulated emission amplification. As the gain medium of the laser, the ytterbium-doped double-clad fiber can absorb the energy of the pump laser and convert it into laser output through stimulated emission amplification. The design of the double-cladding structure enables the pump light to be more effectively absorbed and utilized by the fiber.

[0039] In a nanosecond pulse fiber laser, a laser seed source generates an initial pulse laser, which is then amplified by an ytterbium-doped double-clad fiber. A pump laser provides energy to excite the ytterbium ions in the fiber, thereby generating a population inversion and forming gain. The output power of the laser can be controlled by adjusting parameters such as the power of the pump laser and the length of the ytterbium-doped double-clad fiber. This embodiment can achieve a wider frequency tuning range and high-speed modulation by directly modulating a semiconductor laser diode, thereby generating laser pulses of different pulse widths. The combination of a pump laser and an ytterbium-doped double-clad fiber can maintain the stability and coherence of the seed laser while amplifying the laser, further improving the frequency tuning range and achieving tunable pulse width.

[0040] In some embodiments of the present application, the directly modulated semiconductor laser diode is an SLD semiconductor laser diode, the line width of the SLD semiconductor laser diode 11 is less than 15 nm, the output optical fiber is Hi1060 optical fiber, the pulse width range is 5-500ns, and the repetition frequency is 1-4500kHz.

[0041] The SLD semiconductor laser diode 11 is a superluminescent diode, which is a light source that combines the characteristics of a light-emitting diode and a semiconductor laser, has broadband emission characteristics, and can be directly modulated. . The line width of the SLD semiconductor laser diode 11 is a key indicator for measuring the spectral purity of the light source. The line width is less than 15nm, so the SLD semiconductor laser diode 11 of this embodiment has a relatively high spectral purity. The output optical fiber is Hi1060 optical fiber, which is a high-performance optical fiber designed for optical signal transmission near a wavelength of 1060nm. It usually has the characteristics of low attenuation, high bending resistance and good environmental stability, and is very suitable for laser transmission systems. The output of the SLD is transmitted through the Hi1060 optical fiber to ensure stable and efficient transmission of the optical signal. The laser seed source pulse width range is 5-500ns, which can generate nanosecond laser pulses. The repetition frequency refers to the number of pulses generated by the light source per second. The laser seed source repetition frequency is 1-4500kHz, which can be freely selected within this range according to needs, and the repetition frequency of some pulse widths can be less than 4500kHz.

[0042] In some embodiments of the present application, the nanosecond pulse fiber laser also includes a first online isolator 12, which is connected between the laser seed source and the amplification component. The first online isolator 12 has a central wavelength of 1059 nm, an operating bandwidth of 16 nm, an input optical fiber of Hi1060 optical fiber, and an output optical fiber of 10 / 125 single-clad optical fiber. The average power it withstands is 300 mW, the insertion loss is less than 3 dB, and the isolation is greater than 25 dB.

[0043] The first online isolator 12 is located between the laser seed source and the amplifying component. It can not only prevent the reverse propagation of the optical signal, protect the laser and other components in the system from damage by reflected light, but also ensure the stability and efficiency of the optical signal during transmission. The central wavelength refers to the wavelength at which the online isolator works best. The central wavelength is 1059nm. The laser at this wavelength has good unidirectional transmission. The working bandwidth refers to the wavelength range in which the isolator can effectively isolate the optical signal. In this embodiment, the working bandwidth is 16nm, which means that the isolator can provide effective isolation effect in a wider wavelength range near 1059nm. The input optical fiber is the port at which the isolator receives the optical signal from the laser seed source. The first online isolator 12 uses Hi1060 optical fiber as the input optical fiber, which can ensure the efficient transmission and stable performance of the optical signal. The output optical fiber is the port at which the isolator transmits the optical signal to the amplifying component. The first online isolator 12 uses 10 / 125 single-clad optical fiber as the output optical fiber, which can ensure the stability and efficiency of the optical signal during transmission. The average power is the maximum average optical power that the isolator can withstand. The first online isolator 12 has an average power of 300mW, which means that the isolator can operate stably for a long time without exceeding this power level. Insertion loss refers to the loss introduced by the isolator during the transmission of optical signals. The insertion loss of the first online isolator 12 is less than 3dB, indicating that it has low energy loss. Isolation refers to the ability of the isolator to suppress reverse propagating optical signals. The isolation of the first online isolator 12 is greater than 25dB, indicating that the isolator has excellent reverse optical signal suppression capabilities.

[0044] In some embodiments of the present application, the amplification component includes a first-stage amplification component 2, which includes a first pump laser 21, a first ytterbium-doped double-clad optical fiber 23 and a first beam combiner 22; the signal end of the first beam combiner 22 is connected to a laser seed source, the pump end of the first beam combiner 22 is connected to the first pump laser 21, and the output end of the first beam combiner 22 is connected to the first ytterbium-doped double-clad optical fiber 23, so that the first pump laser 21 provides a pump laser to the first ytterbium-doped double-clad optical fiber 23. excitation; the output power of the first pump laser 21 is greater than 10W, the central wavelength is 915nm±5nm, and the output optical fiber is a 105 / 125 multimode optical fiber; the first ytterbium-doped double-clad optical fiber 23 is an ytterbium-doped 10 / 125 double-clad optical fiber; the optical fiber at the signal end of the first combiner 22 is a 10 / 125 double-clad optical fiber, the optical fiber at the pump end is a 105 / 125 multimode optical fiber, the pump light coupling efficiency is greater than 95%, the signal light withstand power is greater than 2W, and the pump light withstand power is greater than 10W.

[0045] The first-stage amplifier component 2 is responsible for the preliminary amplification of the optical signal generated by the laser seed source. The first-stage amplifier component 2 includes a first pump laser 21, a first ytterbium-doped double-clad fiber 23 and a first beam combiner 22. In the first-stage amplifier component 2, the optical signal generated by the laser seed source first enters the first beam combiner 22 through the signal end of the first beam combiner 22. At the same time, the pump light signal generated by the first pump laser 21 enters the first beam combiner 22 through the pump end of the first beam combiner 22. Inside the first beam combiner 22, the signal light and the pump light are combined and transmitted to the first ytterbium-doped double-clad fiber 23. In the first ytterbium-doped double-clad fiber 23, the pump light is absorbed by ytterbium ions and converted into energy, which is then used to amplify the signal light. The amplified signal light is then output from the output end of the ytterbium-doped double-clad fiber for subsequent amplification or application.

[0046] The output power of the first pump laser 21 is greater than 10W, ensuring sufficient pump energy for amplifying optical signals; the central wavelength is 915nm±5nm, which is a pump wavelength that is well adapted to the ytterbium-doped optical fiber; the output optical fiber is a 105 / 125 multimode optical fiber, which has a large core diameter and can accommodate multiple optical modes, and is suitable for the transmission of high-power pump light. The first ytterbium-doped double-clad optical fiber 23 is the core part of the amplification component, which uses the energy level transition of ytterbium ions to amplify optical signals. The specification of the first ytterbium-doped double-clad optical fiber 23 in this embodiment is 10 / 125, which means that the core diameter of the optical fiber is 10μm and the cladding diameter is 125μm.

[0047] The signal end of the first beam combiner 22 is used to receive the optical signal from the laser seed source, and transmit it to the ytterbium-doped double-clad optical fiber after merging it with the pump light. A 10 / 125 double-clad optical fiber is used. The pump end is used to receive the optical signal from the pump laser and guide it to the cladding of the ytterbium-doped double-clad optical fiber. A 105 / 125 multimode optical fiber is used, which is compatible with the first pump laser 21. The pump light coupling efficiency is one of the important indicators to measure the performance of the beam combiner. It indicates the proportion of the pump light signal that is effectively coupled to the ytterbium-doped double-clad optical fiber. The coupling efficiency of the first beam combiner 22 is greater than 95%, ensuring efficient pump excitation. The signal light withstand power indicates the maximum signal light power that the beam combiner can handle. The withstand power of the first beam combiner 22 greater than 2W ensures that the beam combiner can process the optical signal from the laser seed source, and transmit it to the ytterbium-doped double-clad optical fiber after merging it with the pump light. The pump light withstand power indicates the maximum pump light power that the beam combiner can handle. The power handling capacity of the first beam combiner 22 of more than 10 W ensures that the beam combiner can process the optical signal from the pump laser and effectively couple it into the Yb-doped double-clad optical fiber.

[0048] In some embodiments of the present application, the amplifier assembly includes a secondary amplifier assembly 3, which includes a second pump laser 33, a second ytterbium-doped double-clad fiber 31, and a second combiner 32; the second ytterbium-doped double-clad fiber 31 is connected to the primary amplifier assembly 2, the pump end of the second combiner 32 is connected to the second pump laser 33, and the output end of the second combiner 32 is connected to the second ytterbium-doped double-clad fiber 31, so that the second pump laser 33 provides pump excitation to the second ytterbium-doped double-clad fiber 31, and the signal end of the second combiner is connected to the second pump laser 33. As the output end of the secondary amplification component; the second pump laser 33 has an output power greater than 30W, a central wavelength of 915nm±5nm, and an output optical fiber is a 105 / 125 multimode optical fiber; the second ytterbium-doped double-clad optical fiber 31 is an ytterbium-doped 10 / 125 double-clad optical fiber; the optical fiber at the signal end of the second combiner 32 is a 10 / 125 double-clad optical fiber, and the optical fiber at the pump end is a 105 / 125 multimode optical fiber, the pump light coupling efficiency is greater than 95%, the signal light withstand power is greater than 10W, and the pump light withstand power is greater than 30W.

[0049] The secondary amplifier component 3 is used to further amplify the optical signal output by the primary amplifier component 2, and mainly includes a second pump laser 33, a second ytterbium-doped double-clad optical fiber 31 and a second combiner 32. The signal light from the primary amplifier component 2 enters the second ytterbium-doped double-clad optical fiber 31. At the same time, the pump light signal generated by the second pump laser 33 enters the combiner through the pump end of the combiner, and the pump light is combined and transmitted to the second ytterbium-doped double-clad optical fiber 31. In the ytterbium-doped double-clad optical fiber, the pump light is absorbed by the ytterbium ions and generates a population inversion to form a gain, which is then used to further amplify the signal light. The signal light after secondary amplification is then output from the signal end of the second combiner 32 and can be used for subsequent amplification, modulation or application. The signal end of the second combiner 32 serves as the output end of the secondary amplifier component 3, which can ensure that the output signal light is purer and does not contain the pump light component. The central wavelength and output fiber of the second pump laser 33 are consistent with those of the first pump laser 21, but the output power is greater than 30W, ensuring that sufficient pump energy is provided for the ytterbium-doped double-clad fiber to achieve efficient amplification of the optical signal. The second ytterbium-doped double-clad fiber 31 adopts the same specifications as the first ytterbium-doped double-clad fiber 23. The signal end fiber, pump end fiber, and pump light coupling efficiency of the second combiner 32 are consistent with those of the first combiner 22, but the signal light withstands a power greater than 10W and the pump light withstands a power greater than 30W, thereby meeting the laser requirements after amplification by the first-stage amplifier component 2.

[0050] In some embodiments of the present application, the nanosecond pulse fiber laser also includes a second online isolator 34, which is connected between the first ytterbium-doped double-clad fiber 23 and the second ytterbium-doped double-clad fiber 31; the central wavelength of the second online isolator 34 is 1062nm, the working bandwidth is 20nm, the input fiber is a 10 / 125 single-clad fiber, the output fiber is a 10 / 125 single-clad fiber, the average power it withstands is 2W, the insertion loss is less than 1.5dB, and the isolation is greater than 25dB.

[0051] The second online isolator 34 is placed between the first ytterbium-doped double-clad fiber 23 and the second ytterbium-doped double-clad fiber 31, and its central wavelength is 1062nm, which is consistent with the seed source laser wavelength. The working bandwidth is 20nm, which means that the second online isolator 34 can provide effective isolation effect within the wavelength range of 1062nm±10nm. Both the input fiber and the output fiber are 10 / 125 single-clad fibers, which are compatible with the first-stage amplification component 2. The insertion loss is less than 1.5dB, and the attenuation of the optical signal is small, thereby maintaining the efficient transmission of the optical signal. The attenuation of the optical signal is small, thereby maintaining the efficient transmission of the optical signal. The isolation is greater than 25dB, which ensures that the isolator can effectively prevent the optical signal from propagating in the optical fiber system in reverse, thereby protecting the stability and performance of the laser.

[0052] In some embodiments of the present application, the amplification component includes a three-stage amplification component 4, and the three-stage amplification component 4 includes a third pump laser 44, a third ytterbium-doped double-clad fiber 42 and a third combiner 43; the third ytterbium-doped double-clad fiber 42 is connected to the two-stage amplification component, the pump end of the third combiner 43 is connected to the third pump laser 44, and the output end of the third combiner 43 is connected to the third ytterbium-doped double-clad fiber 42, so that the third pump laser 44 provides pump excitation to the third ytterbium-doped double-clad fiber 42, and the signal end of the third combiner 43 serves as the third amplification component. The output end of the stage amplifier component 4; the output power of the third pump laser 44 is greater than 200W, the central wavelength is 915nm±5nm, and the output optical fiber is a 135 / 155 multimode optical fiber; the third ytterbium-doped double-clad optical fiber 42 is an ytterbium-doped 30 / 250 double-clad optical fiber; the optical fiber at the signal end of the third combiner 43 is a 30 / 250 double-clad optical fiber, the optical fiber at the pump end is a 135 / 155 multimode optical fiber, the pump light coupling efficiency is greater than 95%, the signal light withstand power is greater than 100W, and the single-arm pump light withstand power is greater than 200W.

[0053] The three-stage amplifier component 4 is an amplifier component after the two-stage amplifier component 3 in the nanosecond pulse fiber laser system, and mainly includes a third pump laser 44, a third ytterbium-doped double-clad fiber 42, and a third combiner 43. In the three-stage amplifier component 4, the signal light from the two-stage amplifier component 3 enters the third ytterbium-doped double-clad fiber 42. At the same time, the pump light signal generated by the third pump laser 44 enters the combiner through the pump end of the combiner, and the pump light is combined and transmitted to the third ytterbium-doped double-clad fiber 42. In the ytterbium-doped double-clad fiber, the pump light is absorbed by the ytterbium ions and generates a population inversion to form a gain, which is then used to further amplify the signal light. The signal light after the three-stage amplification is then output from the signal end of the third combiner 43. The signal end of the third combiner 43 is used as the output end of the three-stage amplifier component 4, which can ensure that the output signal light is purer and does not contain the pump light component. The output power of the third pump laser 44 is greater than 200W, ensuring sufficient pump energy for the ytterbium-doped double-clad optical fiber to achieve efficient amplification of optical signals, thereby meeting the processing requirements of laser processing, marking, welding, etc. The central wavelength is 915nm±5nm, which matches the absorption characteristics of the third ytterbium-doped double-clad optical fiber 42. The output optical fiber is a 135 / 155 multimode optical fiber, which supports multimode transmission and is suitable for the transmission of high-power pump light. The third ytterbium-doped double-clad optical fiber 42 adopts ytterbium-doped 30 / 250 double-clad optical fiber, which helps to withstand high-power optical signals and achieve efficient amplification. The optical fiber at the signal end of the third combiner 43 is a 30 / 250 double-clad optical fiber, and the optical fiber at the pump end is a 135 / 155 multimode optical fiber. The pump light coupling efficiency is greater than 95%, the signal light withstand power is greater than 100W, and the single-arm pump light withstand power is greater than 200W, which can meet the needs of three-stage amplification.

[0054] In some embodiments of the present application, the nanosecond pulse fiber laser also includes a third online isolator 34, which is connected between the second ytterbium-doped double-clad fiber 31 and the third ytterbium-doped double-clad fiber 42; the central wavelength of the third online isolator 34 is 1062nm, the working bandwidth is 20nm, the input fiber is a 10 / 125 double-clad fiber, the output fiber is a 10 / 125 double-clad fiber, the average power it withstands is 10W, the insertion loss is less than 1dB, and the isolation is greater than 25dB.

[0055] The third online isolator 34 is connected between the second ytterbium-doped double-clad fiber 31 and the third ytterbium-doped double-clad fiber 42 to prevent the reverse propagation of the laser after the secondary amplification component 3. The central wavelength of the third online isolator 34 is 1062nm, and the working bandwidth is 20nm. It can provide effective isolation effect within the wavelength range of 1062nm±10nm, covering most of the wavelength range of the optical signal that the laser may generate. The input fiber is a 10 / 125 double-clad fiber, and the output fiber is a 10 / 125 double-clad fiber, which matches the second ytterbium-doped double-clad fiber 31; the average power is 10W, the insertion loss is less than 1dB, and the isolation is greater than 25dB, which can meet the laser requirements after secondary amplification.

[0056] In some embodiments of the present application, the nanosecond pulse fiber laser also includes a mode field adapter 41, which is connected between the third online isolator 34 and the three-stage amplification component 4. The input end of the mode field adapter 41 is a 10 / 125 double-clad optical fiber, and the output end is a 30 / 250 double-clad optical fiber, which can withstand an average power greater than 10W.

[0057] The mode field adapter 41 is arranged between the third online isolator 34 and the three-stage amplification component 4, and its input end is a 10 / 125 double-clad fiber matched with the third online isolator 34, and its output end is a 30 / 250 double-clad fiber matched with the third ytterbium-doped double-clad fiber 42. The average power is greater than 10W, which can withstand the laser power after the second-stage amplification.

[0058] In some embodiments of the present application, the nanosecond pulse fiber laser also includes an output isolator 51, which is arranged at the output end of the three-stage amplification component 4. The working wavelength of the output isolator 51 is 1064nm, and the input optical fiber is a 30 / 250 double-clad optical fiber. It can withstand an average power greater than 100W, a peak power greater than 20kW, and an isolation greater than 25dB.

[0059] The output isolator 51 is arranged at the output end of the three-stage amplification component 4, which can prevent the reverse transmission of the laser after the three-stage amplification component 4. The working wavelength of the output isolator 51 is 1064nm, which matches the main wavelength generated by the laser, thereby ensuring the efficient transmission of the optical signal. The input end adopts a 30 / 250 double-clad optical fiber that matches the third ytterbium-doped double-clad optical fiber 42. It can withstand an average power greater than 100W and a peak power greater than 20kW, and can withstand the laser power after three-stage amplification. The isolation is greater than 25dB, so that the output isolator 51 can effectively attenuate the reflected light.

[0060] The following is an embodiment of the present application.

[0061] like Figure 1As shown, a time-domain high-precision tunable nanosecond pulse fiber laser of this example mainly includes four parts, namely a seed source component 1, which is composed of an SLD semiconductor laser diode 11 and a first online isolator 12; a first-stage amplification component 2, which is composed of a first pump laser 21, a first combiner 22, a first ytterbium-doped double-clad fiber 23, and a second online isolator 24; a second-stage amplification component 3, which is composed of a second ytterbium-doped double-clad fiber 31, a second combiner 32, a second pump laser 33, and a second online isolator 34; a third-stage amplification component 4, which is composed of a mode field adapter 41, a third ytterbium-doped double-clad fiber 42, a third combiner 43, and a third pump laser 44. The structural relationship between the various components is: the output end of the SLD semiconductor laser diode is connected to the input end of the first online isolator, the output end of the first online isolator is connected to the signal end of the first combiner, the output end of the first pump laser is connected to the pump end of the first combiner, the output end of the first combiner is connected to the first ytterbium-doped double-clad fiber, the other end of the first ytterbium-doped double-clad fiber is connected to the input end of the second online isolator, the output end of the second online isolator is connected to the second ytterbium-doped double-clad fiber, the other end of the second ytterbium-doped double-clad fiber is connected to the output end of the second combiner, the pump end of the second combiner is connected to the second pump laser, the signal end of the second combiner is connected to the input end of the second online isolator, the output end of the second online isolator is connected to the input end of the mode field adapter, the output end of the mode field adapter is connected to the third ytterbium-doped double-clad fiber, the other end of the third ytterbium-doped double-clad fiber is connected to the output end of the third combiner, the pump end of the third combiner is connected to the third pump laser, and the signal end of the third combiner is connected to the input end of the output isolator 51.

[0062] The SLD semiconductor laser diode 11, in this example, is an SLD semiconductor laser diode, with a central wavelength of 1064nm, a line width less than 15nm, an output fiber optic Hi1060 fiber, an output state of pulse, a pulse width range of 5-500ns, a total of 100 pulse widths to choose from, a repetition frequency of 1-4500kHz, and a repetition frequency of some pulse widths less than 4500kHz.

[0063] In this example, the first-stage amplifier component 2, the second-stage amplifier component 3, and the third-stage amplifier component 4 all use a cladding-pumped MOPA structure to amplify the signal light. In this example, each amplifier module uses ytterbium-doped double-clad optical fiber, and the pump light source uses a 915nn multi-mode semiconductor laser. Using a three-stage amplifier structure, the seed source power is amplified to an average power of 100W, a peak power greater than 20kW, and a single pulse energy greater than 1.5mJ. The pulse width tuning accuracy can reach 5ns, the frequency range is 1-4500kHz, the pulse width range is 5-500ns, and a total of 100 pulse widths are optional, achieving high repetition rate, high power, high beam quality, and high time domain tuning accuracy. Nanosecond pulse laser output. The optical path structure of this example is compact, simple, and the output beam quality is excellent. It is understood that it is the first time-domain high-precision tunable nanosecond pulse fiber laser in the field.

[0064] In general, the nanosecond pulse fiber laser of this embodiment utilizes a reasonably designed output waveform, more appropriate optical path selection, and optimized gain distribution to maintain a good output spectrum for each stage of the fiber amplifier. After three-stage amplifier amplification, it achieves an average power of 100W, a peak power greater than 20kW, and a single pulse energy greater than 1.5mJ. The pulse width tuning accuracy can reach 5ns, the frequency range is 1-4500kHz, the pulse width range is 5-500ns, and a total of 100 pulse widths are optional, achieving high repetition rate, high power, high beam quality, and high time domain tuning accuracy nanosecond pulse laser output, which is an ideal laser light source for laser marking and laser precision welding.

[0065] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A nanosecond pulse fiber laser, characterized in that: The nanosecond pulse fiber laser comprises: Laser seed source; the laser seed source is a directly modulated semiconductor laser diode with a central wavelength of 1064nm and a pulse output state; At least one amplification component; the amplification component includes a pump laser and an ytterbium-doped double-clad optical fiber, the central wavelength of the pump laser is 915±5nm, the laser seed source is connected to the ytterbium-doped double-clad optical fiber, and the pump laser is connected to the ytterbium-doped double-clad optical fiber.

2. The nanosecond pulse fiber laser according to claim 1, characterized in that: The directly modulated semiconductor laser diode is an SLD semiconductor laser diode, the line width of the SLD semiconductor laser diode is less than 15nm, the output optical fiber is Hi1060 optical fiber, the pulse width range is 5-500ns, and the repetition frequency is 1-4500kHz.

3. The nanosecond pulse fiber laser according to claim 1, characterized in that: The nanosecond pulse fiber laser also includes a first online isolator, which is connected between the laser seed source and the amplification component. The first online isolator has a central wavelength of 1059 nm, a working bandwidth of 16 nm, an input optical fiber of Hi1060 optical fiber, an output optical fiber of 10 / 125 single-clad optical fiber, an average power of 300 mW, an insertion loss of less than 3 dB, and an isolation of greater than 25 dB.

4. The nanosecond pulse fiber laser according to claim 1, characterized in that: The amplification component comprises a first-stage amplification component, and the first-stage amplification component comprises a first pump laser, a first ytterbium-doped double-clad optical fiber and a first beam combiner; The signal end of the first beam combiner is connected to the laser seed source, the pump end of the first beam combiner is connected to the first pump laser, and the output end of the first beam combiner is connected to the first ytterbium-doped double-clad optical fiber, so that the first pump laser provides pump excitation to the first ytterbium-doped double-clad optical fiber; The output power of the first pump laser is greater than 10W, the central wavelength is 915nm±5nm, and the output optical fiber is a 105 / 125 multimode optical fiber; the first ytterbium-doped double-clad optical fiber is an ytterbium-doped 10 / 125 double-clad optical fiber; the optical fiber at the signal end of the first combiner is a 10 / 125 double-clad optical fiber, the optical fiber at the pump end is a 105 / 125 multimode optical fiber, the pump light coupling efficiency is greater than 95%, the signal light withstand power is greater than 2W, and the pump light withstand power is greater than 10W.

5. The nanosecond pulse fiber laser according to claim 4, characterized in that: The amplification component includes a secondary amplification component, and the secondary amplification component includes a second pump laser, a second ytterbium-doped double-clad optical fiber, and a second beam combiner; The second ytterbium-doped double-clad optical fiber is connected to the first-stage amplification component, the pump end of the second beam combiner is connected to the second pump laser, and the output end of the second beam combiner is connected to the second ytterbium-doped double-clad optical fiber, so that the second pump laser provides pump excitation to the second ytterbium-doped double-clad optical fiber, and the signal end of the second beam combiner serves as the output end of the second-stage amplification component; The output power of the second pump laser is greater than 30W, the central wavelength is 915nm±5nm, and the output optical fiber is a 105 / 125 multimode optical fiber; the second ytterbium-doped double-clad optical fiber is an ytterbium-doped 10 / 125 double-clad optical fiber; the optical fiber at the signal end of the second combiner is a 10 / 125 double-clad optical fiber, the optical fiber at the pump end is a 105 / 125 multimode optical fiber, the pump light coupling efficiency is greater than 95%, the signal light withstand power is greater than 10W, and the pump light withstand power is greater than 30W.

6. The nanosecond pulse fiber laser according to claim 5, characterized in that: The nanosecond pulse fiber laser further comprises a second online isolator, wherein the second online isolator is connected between the first ytterbium-doped double-clad fiber and the second ytterbium-doped double-clad fiber; The central wavelength of the second online isolator is 1062nm, the working bandwidth is 20nm, the input fiber is 10 / 125 single-clad fiber, the output fiber is 10 / 125 single-clad fiber, the average power it withstands is 2W, the insertion loss is less than 1.5dB, and the isolation is greater than 25dB.

7. The nanosecond pulse fiber laser according to claim 5, characterized in that: The amplification component comprises a three-stage amplification component, and the two-stage amplification component comprises a third pump laser, a third ytterbium-doped double-clad optical fiber and a third beam combiner; The third ytterbium-doped double-clad optical fiber is connected to the secondary amplification component, the pump end of the third beam combiner is connected to the third pump laser, and the output end of the third beam combiner is connected to the third ytterbium-doped double-clad optical fiber, so that the third pump laser provides pump excitation to the third ytterbium-doped double-clad optical fiber, and the signal end of the third beam combiner serves as the output end of the three-stage amplification component; The output power of the third pump laser is greater than 200W, the central wavelength is 915nm±5nm, and the output optical fiber is a 135 / 155 multimode optical fiber; the third ytterbium-doped double-clad optical fiber is an ytterbium-doped 30 / 250 double-clad optical fiber; the optical fiber at the signal end of the third combiner is a 30 / 250 double-clad optical fiber, the optical fiber at the pump end is a 135 / 155 multimode optical fiber, the pump light coupling efficiency is greater than 95%, the signal light withstand power is greater than 100W, and the single-arm pump light withstand power is greater than 200W.

8. The nanosecond pulse fiber laser according to claim 7, characterized in that: The nanosecond pulse fiber laser further comprises a third online isolator, wherein the third online isolator is connected between the second ytterbium-doped double-clad fiber and the third ytterbium-doped double-clad fiber; The central wavelength of the third online isolator is 1062nm, the working bandwidth is 20nm, the input optical fiber is 10 / 125 double-clad optical fiber, the output optical fiber is 10 / 125 double-clad optical fiber, the average power it withstands is 10W, the insertion loss is less than 1dB, and the isolation is greater than 25dB.

9. The nanosecond pulse fiber laser according to claim 8, characterized in that: The nanosecond pulse fiber laser also includes a mode field adapter, which is connected between the third online isolator and the three-stage amplification component. The input end of the mode field adapter is a 10 / 125 double-clad optical fiber, and the output end is a 30 / 250 double-clad optical fiber, and can withstand an average power greater than 10W.

10. The nanosecond pulse fiber laser according to claim 7, characterized in that: The nanosecond pulse fiber laser also includes an output isolator, which is arranged at the output end of the three-stage amplification component. The output isolator has an operating wavelength of 1064nm, and the input optical fiber is a 30 / 250 double-clad optical fiber. It can withstand an average power greater than 100W, a peak power greater than 20kW, and an isolation greater than 25dB.

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