Tunable fiber laser and control method thereof

Abstract

The invention relates to the technical field of lasers, in particular to a tunable fiber laser and a control method thereof. The tunable fiber laser comprises: a seed source module configured to output initial laser; the seed source module comprises multiple of a continuous and quasi-continuous laser sub-module, a nanosecond laser sub-module and a picosecond laser sub-module; the type of the initial laser corresponds to the type of the laser sub-module included in the seed source module; a first beam combiner; the seed source module is connected with the amplifier module through a first beam combiner; the amplifier module is configured to amplify the initial laser to form target laser; and the control module is in communication connection with the seed source module and the amplifier module so as to regulate and control the type of the laser output by the seed source module and regulate and control the working state of the amplifier module. The same laser can output various lasers with different types and intensities, the light source cost needed by laser processing materials is reduced, and the processing efficiency is improved.

Description

Technical Field

[0001] The present application relates to the field of laser technology, and in particular to a tunable fiber laser and a control method thereof. Background Art

[0002] Multi-laser composite manufacturing refers to the use of multiple lasers with different performance parameters to participate in the same processing process and change the material properties. It overcomes the weaknesses of single laser manufacturing technology in terms of quality, efficiency, cost, etc., and achieves the effect of one plus one being greater than two. It is becoming a research trend in the current laser manufacturing field. Among common industrial lasers, continuous lasers are suitable for rough cutting and welding of materials, quasi-continuous lasers are suitable for precision spot welding, nanosecond pulse lasers are suitable for surface cleaning and marking of materials, and picosecond lasers are suitable for precision cutting and engraving of materials. If it is necessary to use the above multiple laser processes continuously, the traditional method is to place the samples to be processed on different types of laser processing machines in turn for processing. If a shared laser processing platform is used, it is necessary to repeatedly replace the laser, or to couple the lasers output by multiple lasers to the same laser processing platform through a complex laser beam combining device.

[0003] It can be seen that the current need to use a variety of laser processing materials requires a high light source cost and low laser processing efficiency.

[0004] Therefore, it is urgent to propose a fiber laser that can output multiple lasers to solve the above technical problems. Summary of the invention

[0005] The embodiments of the present application provide a tunable fiber laser and a control method thereof, which enable the same laser to output lasers of different types and intensities using the same fiber, thereby reducing the cost of light sources required for processing materials using different lasers and improving the material processing efficiency of laser processing.

[0006] In some embodiments, a tunable fiber laser is provided, including: a seed source module, the seed source module is configured to output an initial laser; the seed source module includes multiple types of continuous and quasi-continuous laser sub-modules, nanosecond laser sub-modules and picosecond laser sub-modules; the type of the initial laser corresponds to the type of the laser sub-module included in the seed source module; a first beam combiner; an amplifier module, the seed source module and the amplifier module are connected through the first beam combiner; the amplifier module is configured to amplify the initial laser to form a target laser; and a control module, which is communicatively connected to the seed source module and the amplifier module, respectively, to regulate the type of laser output by the seed source module and regulate the working state of the amplifier module.

[0007] By using the tunable fiber laser provided in the embodiment of the present application, different types of laser submodules in the seed source module can be switched through the control module to change the type of the initial laser. In addition, the working state of the amplifier module is regulated by the control module so that the amplifier module amplifies the initial laser to obtain the target laser. The parameters such as the laser type and intensity output by the tunable fiber laser can be regulated and changed, so that the tunable fiber laser provided in the embodiment of the present application can be used to output a variety of lasers of different types and intensities, reduce the cost of the light source required for using different laser processing materials, and improve the processing efficiency of laser processed materials.

[0008] Optionally, the continuous and quasi-continuous laser submodule is configured to output continuous laser and / or quasi-continuous laser; the continuous and quasi-continuous laser submodule includes: a second beam combiner, a first high-reflection grating, a first gain fiber and a low-reflection grating arranged in sequence along the optical axis; the first high-reflection grating and the low-reflection grating form a first resonant cavity; the first gain fiber is configured to provide laser gain; the continuous and quasi-continuous laser submodule also includes: a first semiconductor pump laser, configured to output a first pump laser; the first pump laser is coupled to the first gain fiber through the second beam combiner; the first semiconductor pump laser The number of the first semiconductor pump lasers is one or more; when the number of the first semiconductor pump lasers is multiple, multiple first pump lasers output by the multiple first semiconductor pump lasers are combined into a total pump laser through the second beam combiner and coupled to the first gain fiber; wherein the first semiconductor pump laser is driven to output the first pump laser, the first pump laser enters the first resonant cavity through the first high-reflection grating, the first pump laser oscillates in the first resonant cavity along the first gain fiber, and part of the first pump laser outputs the first resonant cavity through the low-reflection grating to output continuous laser and / or quasi-continuous laser.

[0009] Optionally, the nanosecond laser submodule is configured to output nanosecond laser; the nanosecond laser submodule includes: a single-mode semiconductor laser, a first optical isolator, a first wavelength division multiplexer, a second gain fiber, and a second semiconductor pump laser arranged in sequence along the optical axis; the single-mode semiconductor laser is configured to be driven by a pulse current source to output a seed laser; the first optical isolator is configured to resist reflected light in a subsequent optical path of the first optical isolator; the second gain fiber is configured to provide laser gain; the second optical isolator is configured to resist reflected light in a subsequent optical path of the second optical isolator; the second semiconductor pump laser is configured to output a second pump laser to the second gain fiber; the second pump laser output by the second semiconductor pump laser is coupled to the second gain fiber through the first wavelength division multiplexer; wherein the single-mode semiconductor laser outputs a seed laser, the seed laser enters the second gain fiber after passing through the first optical isolator, the second pump laser output by the second semiconductor pump laser is coupled to the seed laser to form a coupled laser, and the second pump laser, the seed laser and the coupled laser pass through the second optical isolator along the second gain fiber to output the nanosecond laser.

[0010] Optionally, the picosecond laser submodule is configured to output picosecond laser; the picosecond laser submodule includes: a semiconductor saturable absorber mirror, a second wavelength division multiplexer, a third gain fiber, a beam splitter and a second high-reflection grating arranged in sequence along the optical axis; the semiconductor saturable absorber mirror and the second high-reflection grating form a second resonant cavity; the third gain fiber is configured to provide laser gain; the beam splitter includes a first branch optical path and a second branch optical path, and the first branch optical path is optically connected to the second high-reflection grating; the picosecond laser submodule also includes: a pulse selector and a third optical isolator connected in sequence to the second branch optical path; a third semiconductor pump laser, the third semiconductor pump laser is configured to output a third pump laser to the third gain fiber; the third semiconductor pump The third pump laser output by the semiconductor laser is coupled to the third gain fiber through the second wavelength division multiplexer; the beam splitter is configured to divide the third pump laser in the second resonant cavity into a first sub-laser and a second sub-laser, the first sub-laser is configured to resonate in the second resonant cavity, and the second sub-laser is configured to form an initial laser; wherein, the third semiconductor pump laser outputs the third pump laser, the third pump laser is coupled to the third gain fiber through the second wavelength division multiplexer, the third pump laser is divided by the beam splitter into a first sub-laser via the first branch optical path and a second sub-laser via the second branch optical path, the first sub-laser resonates in the second resonant cavity, the second sub-laser is output and passes through the pulse selector and the third optical isolator to output picosecond laser.

[0011] Optionally, the seed source module also includes: a state detection device configured to detect whether the seed source module is working; the continuous and quasi-continuous laser sub-module includes a second beam combiner; the state detection device includes a first photodetector, and the first photodetector is connected to the second beam combiner; the nanosecond laser sub-module includes a second optical isolator; the state detection device includes a sampling beam splitter and a second photodetector connected to the second optical isolator in sequence; the sampling beam splitter is configured to extract part of the initial laser output by the second optical isolator to the second photodetector; the picosecond laser sub-module includes a second high-reflection grating; the state detection device includes a third photodetector, and the third photodetector is connected to the second high-reflection grating; and / or, a semiconductor refrigeration plate, and other devices in the seed source module are all arranged on the semiconductor refrigeration plate.

[0012] Optionally, the amplifier module includes: one or more amplifier sub-modules; the amplifier sub-module includes a light inlet and a light outlet; when the amplifier module includes multiple amplifier sub-modules, the multiple amplifier sub-modules are connected in sequence, and the light inlet of the amplifier sub-module is connected in sequence to the light outlet of the previous amplifier sub-module; the amplifier sub-module includes: an isolation filter and a fourth gain optical fiber arranged in sequence along the optical axis; the isolation filter is configured to filter out clutter in the laser entering from the light inlet and resist reflected light in a subsequent optical path of the isolation filter; the amplifier sub-module also includes: a third beam combiner and a fourth semiconductor pump laser; the number of the fourth semiconductor pump laser is one or more; the fourth pump laser output by the fourth semiconductor pump laser is coupled to the fourth gain optical fiber through the third beam combiner.

[0013] Optionally, when there are multiple fourth semiconductor pump lasers, the central wavelength of each fourth semiconductor pump laser is different.

[0014] Optionally, in the amplifier sub-modules connected in sequence, the fiber core diameters of the fourth gain fibers increase in sequence.

[0015] Optionally, the control module includes: a laser main control submodule and a power driver submodule; the laser main control submodule is connected to the seed source module and the power driver submodule through a signal line, and the laser main control submodule is configured to control the seed source module and the power driver submodule; the power driver submodule is connected to the amplifier module and the seed source module through a power line and a signal line, and the power driver submodule is configured to supply energy to the amplifier module and the seed source module, and control the operating current and operating temperature of the amplifier module and the seed source module.

[0016] In some embodiments, a control method for a tunable fiber laser is provided. The control method for a tunable fiber laser is used for a tunable fiber laser as in any one of the above embodiments. The control method for a tunable fiber laser includes: S1, acquiring target laser parameter information; S2, determining seed source operating parameters and amplifier operating parameters corresponding to the target laser parameter information; S3, controlling the seed source module to operate according to the seed source operating parameters; S4, detecting the operating state of the seed source module; S5, when the seed source module is in the operating state, controlling the amplifier module to operate according to the amplifier operating parameters.

[0017] The control method for a tunable fiber laser provided in the embodiment of the present application is used to control the operation of the seed source module and the amplifier module according to the target laser parameter information input by the user, so as to output the target laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the embodiments are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0019] Figure 1 A structural block diagram of a first tunable fiber laser provided in an embodiment of the present application; Figure 2 A structural block diagram of a second tunable fiber laser provided in an embodiment of the present application; Figure 3 A structural block diagram of a third tunable fiber laser provided in an embodiment of the present application; Figure 4 A structural block diagram of a fourth tunable fiber laser provided in an embodiment of the present application; Figure 5 A structural block diagram of the first continuous and quasi-continuous laser submodule provided in an embodiment of the present application; Figure 6 A structural block diagram of the second continuous and quasi-continuous laser submodule provided in an embodiment of the present application; Figure 7 A structural block diagram of the first nanosecond laser submodule provided in an embodiment of the present application; Figure 8 A structural block diagram of a second nanosecond laser submodule provided in an embodiment of the present application; Fig. 9 A structural block diagram of the first picosecond laser submodule provided in an embodiment of the present application; Fig.10 A structural block diagram of a second picosecond laser submodule provided in an embodiment of the present application; Fig.11 A schematic diagram of the structure of the amplifier submodule provided in an embodiment of the present application; Fig.12 A schematic diagram of parameters of a tunable fiber laser outputting continuous laser light provided in an embodiment of the present application; Fig.13 A schematic diagram of parameters of a tunable fiber laser outputting quasi-continuous laser light provided in an embodiment of the present application; Fig.14 A schematic diagram of parameters of a tunable fiber laser outputting nanosecond lasers provided in an embodiment of the present application; Fig.15 A schematic diagram of parameters of a tunable fiber laser outputting picosecond lasers provided in an embodiment of the present application; Fig.16 A schematic flow chart of a control method for a tunable fiber laser provided in an embodiment of the present application.

[0020] Reference numerals: 1. Tunable fiber laser; 11. Seed source module; 111. CW and quasi-CW laser submodule; 111a. First resonant cavity; 111b. First high-reflection grating; 111c. Low-reflection grating; 111d. First gain fiber; 111e. Second beam combiner; 111f. First semiconductor pump laser; 111g. First photodetector; 112. Nanosecond laser submodule; 112a. Single-mode semiconductor laser; 112b. First optical isolator; 112c. First wavelength division multiplexer; 112d. Second gain fiber; 112e. Second optical isolator; 112f. Second semi-conductor Conductor pump laser; 112g, sampling beam splitter; 112h, second photodetector; 113, picosecond laser submodule; 113a, second resonant cavity; 113b, semiconductor saturable absorber mirror; 113c, second high-reflection grating; 113d, third gain fiber; 113e, second wavelength division multiplexer; 113f, beam splitter; 113g, pulse selector; 113h, third optical isolator; 113i, third semiconductor pump laser; 113j, third photodetector; 114, continuous laser submodule; 115, quasi-continuous laser submodule; 12. The first beam combiner; 13. Amplifier module; 131. Isolation filter; 132. Fourth gain fiber; 133. Third beam combiner; 134. Fourth semiconductor pump laser; 135. First amplifier submodule; 136. Second amplifier submodule; 137. Third amplifier submodule; 14. Control module; 141. Laser main control submodule; 142. Power drive submodule. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be described clearly below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments of the present application, other embodiments obtained by ordinary technicians in this field without making creative work all belong to the protection scope of the present application.

[0022] In the following, the terms "first", "second", etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0023] In addition, in the present application, directional terms such as "upper", "lower", "inner" and "outer" are defined relative to the orientation of the components schematically placed in the drawings. It should be understood that these directional terms are relative concepts. They are used for relative description and clarification, and they can change accordingly according to the changes in the orientation of the components placed in the drawings.

[0024] Figure 1 This is a structural block diagram of the first tunable fiber laser provided in an embodiment of the present application.

[0025] Figure 2 This is a structural block diagram of a second tunable fiber laser provided in an embodiment of the present application.

[0026] Figure 3 This is a structural block diagram of the third tunable fiber laser provided in an embodiment of the present application.

[0027] Figure 4 This is a structural block diagram of the fourth tunable fiber laser provided in an embodiment of the present application.

[0028] Combination Figures 1 to 4 As shown, an embodiment of the present application provides a tunable fiber laser 1, comprising: a seed source module 11, a first beam combiner 12, an amplifier module 13 and a control module 14. The seed source module 11 is configured to output an initial laser; the seed source module 11 includes a plurality of continuous and quasi-continuous laser submodules 111, nanosecond laser submodules 112 and picosecond laser submodules 113; the type of the initial laser corresponds to the type of laser submodule included in the seed source module 11. The seed source module 11 is connected to the amplifier module 13 through the first beam combiner 12; the amplifier module 13 is configured to amplify the initial laser to form a target laser. The control module 14 is respectively connected to the seed source module 11 and the amplifier module 13 in communication to adjust the type of laser output by the seed source module 11 and to adjust the working state of the amplifier module 13.

[0029] By using the tunable fiber laser 1 provided in the embodiment of the present application, different types of laser submodules in the seed source module 11 can be switched through the control module 14 to change the type of the initial laser. In addition, the working state of the amplifier module 13 is regulated by the control module 14 so that the amplifier module 13 amplifies the initial laser to obtain the target laser. The parameters such as the type and intensity of the laser output by the tunable fiber laser 1 can be regulated and changed, so that the tunable fiber laser 1 provided in the embodiment of the present application can be used to output a variety of lasers of different types and intensities, reduce the cost of the light source required for processing materials using different lasers, and improve the processing efficiency of laser-processed materials.

[0030] Combination Figure 2 , Figure 3 and Figure 4 As shown, if multiple different types of lasers need to be output, multiple laser sub-modules are required. The input end optical fiber of the first beam combiner 12 is connected to the initial laser output end of each laser sub-module respectively, and the output end optical fiber of the first beam combiner 12 is connected to the input end of the amplifier module 13, so that multiple initial lasers can be transmitted to the amplifier module 13.

[0031] For example, combined with Figure 2 As shown, in the case where the seed source module 11 includes three laser sub-modules, the first combiner 12 includes three input end branches and one output end branch, and the three input end branches are respectively connected to each laser sub-module to receive the initial laser output by each laser sub-module, and output the initial laser to the amplifier module 13 through the output end branch.

[0032] In the embodiment of the present application, various types of laser sub-modules are coupled to the same amplifier module 13 through a first beam combiner 12, and various different types of lasers can be switched and output through the same optical fiber. In this way, only one laser processing machine is required, and the processing of different types of materials can be conveniently adapted without replacing the laser.

[0033] Optionally, the input end optical fiber of the first beam combiner 12 is a signal optical fiber. In this way, the initial laser light received by the input end optical fiber of the first beam combiner 12 will all enter the output end optical fiber of the first beam combiner 12 .

[0034] Specifically, the optical fiber at the input end of the existing commercial laser beam combiner is divided into two types: pump fiber and signal fiber. The pump fiber is used to provide pump laser, which enters the cladding of the optical fiber at the output end. The signal fiber provides signal light, which enters the core of the output optical fiber. Compared with the existing commercial laser beam combiner, the optical fiber at the input end of the first beam combiner 12 provided in the embodiment of the present application is all signal fiber, that is, in the first beam combiner 12 provided in the embodiment of the present application, the initial laser received at the input end all enters the core of the optical fiber at the output end.

[0035] Optionally, the sum of the core areas of the optical fibers at the input end of the first beam combiner 12 is less than or equal to the core area of ​​the optical fibers at the output end. In this way, the problem of the initial laser being leaked from the connection between the input optical fiber and the output optical fiber during the process of the initial laser being transmitted from the input optical fiber of the first beam combiner 12 to the output optical fiber can be avoided, thereby reducing the burning of the laser.

[0036] Specifically, existing commercial laser combiners only require that the core area of ​​the signal fiber be less than or equal to the core area of ​​the output fiber, while the sum of the core areas of all signal fibers of the first combiner 12 provided in the embodiment of the present application must be less than or equal to the core area of ​​the output fiber, thereby reducing the leakage of the initial laser.

[0037] Figure 5 This is a structural block diagram of the first continuous and quasi-continuous laser sub-module provided in an embodiment of the present application.

[0038] Optionally, combined Figure 5As shown, the continuous and quasi-continuous laser submodule 111 is configured to output continuous laser and / or quasi-continuous laser; the continuous and quasi-continuous laser submodule 111 includes: a second beam combiner 111e, a first high-reflection grating 111b, a first gain fiber 111d and a low-reflection grating 111c arranged in sequence along the optical axis; the first high-reflection grating 111b and the low-reflection grating 111c form a first resonant cavity 111a; the first gain fiber 111d is configured to provide laser gain; the continuous and quasi-continuous laser submodule 111 also includes: a first semiconductor pump laser 111f, configured to output a first pump laser; the first pump laser is coupled to the first gain fiber 111d through the second beam combiner 111e; the first semiconductor pump The number of lasers 111f is one or more; when the number of first semiconductor pump lasers 111f is multiple, multiple beams of first pump lasers output by multiple first semiconductor pump lasers 111f are combined into a total pump laser through the second combiner 111e and coupled to the first gain fiber 111d; wherein, the first semiconductor pump laser 111f is driven to output the first pump laser, the first pump laser enters the first resonant cavity 111a through the first high-reflection grating 111b, the first pump laser oscillates in the first resonant cavity 111a along the first gain fiber 111d, and part of the first pump laser is output from the first resonant cavity 111a through the low-reflection grating 111c to output continuous laser and / or quasi-continuous laser.

[0039] In this embodiment, continuous laser and / or quasi-continuous laser can be output through the continuous and quasi-continuous laser submodule 111, that is, the type of the initial laser output by the seed source module 11 is continuous laser or quasi-continuous laser. In addition, by using the continuous and quasi-continuous laser submodule 111 to output two different lasers, the integration of the system is improved, the volume required by the seed source module 11 is reduced, and the cost of the system light source is reduced.

[0040] Specifically, the number of the first semiconductor pump lasers 111f needs to take into account the total demand for pump power of the CW and quasi-CW laser sub-module 111 (the higher the target output power of the CW and quasi-CW laser sub-module 111, the higher the required pump power) and the market production level of the first semiconductor pump laser 111f. For example, for a first semiconductor pump laser 111f with a maximum output power of 200W, if the CW and quasi-CW laser sub-module 111 requires a pump power of 600W, at least three first semiconductor pump lasers 111f are required.

[0041] If there is only one first semiconductor pump laser 111f in the continuous and quasi-continuous laser submodule 111, it is still necessary to set up the second beam combiner 111e. This is because there will be back-reflected light inside the core of the first high-reflection grating 111b. The higher the power of the first semiconductor pump laser 111f, the more back-reflected light there is. If there is no second beam combiner 111e, the first pump laser output by the first semiconductor pump laser 111f will be directly connected to the core of the first high-reflection grating 111b (the second beam combiner 111e connects the first pump laser to the optical fiber cladding of the first high-reflection grating 111b, but not to the core), and the back-reflected light inside the core of the first high-reflection grating 111b will be directly reflected back to the first semiconductor pump laser 111f, causing the first semiconductor pump laser 111f to burn out.

[0042] Optionally, when the first semiconductor pump laser 111f is driven by a constant current source, the continuous and quasi-continuous laser submodule 111 outputs continuous laser, that is, the type of the initial laser output by the seed source module 11 is continuous laser. When the first semiconductor pump laser 111f is driven by a pulse current source with tunable repetition rate and pulse width, the continuous and quasi-continuous laser submodule 111 outputs quasi-continuous laser, that is, the type of the initial laser output by the seed source module 11 is quasi-continuous laser.

[0043] It is understandable that, combined with Figure 3 As shown, the seed source module 11 provided in the embodiment of the present application has a continuous laser submodule 114 and a quasi-continuous laser submodule 115 with the same structure, a constant current source is used to drive the first semiconductor pump laser 111f in the continuous laser submodule 114 to output continuous laser, and a pulse current source with tunable repetition rate and pulse width is used to drive the first semiconductor pump laser 111f in the quasi-continuous laser submodule 115 to output quasi-continuous laser, so that the initial laser output by the seed source module 11 is continuous laser or quasi-continuous laser. Alternatively, in combination with Figure 2 As shown, the seed source module 11 provided in the embodiment of the present application has a continuous and quasi-continuous laser sub-module 111. When the initial laser to be output is a continuous laser, a constant current source is used to drive the first semiconductor pump laser 111f in the continuous laser sub-module 114. When the initial laser to be output is a quasi-continuous laser, a pulse current source with tunable repetition rate and pulse width is used to drive the first semiconductor pump laser 111f in the quasi-continuous laser sub-module 115, so that the initial laser output by the seed source module 11 is a continuous laser or a quasi-continuous laser.

[0044] Specifically, the power of the continuous laser output by the continuous and quasi-continuous laser submodule 111 can be adjusted in the range of 0 W to 500 W. The power of the quasi-continuous laser output by the continuous and quasi-continuous laser submodule 111 can be adjusted in the range of 0 W to 50 W, the frequency can be adjusted in the range of 0 kHz to 5 kHz, and the pulse width can be adjusted in the range of 0.05 ms to 50 ms.

[0045] Optionally, the first gain fiber 111d is a double-clad gain fiber.

[0046] Optionally, the wavelength of the first pump laser is between 900 nm and 980 nm.

[0047] Optionally, the first high-reflection grating 111b and the low-reflection grating 111c have the same preset central wavelength, and the preset central wavelength is 1030nm, 1064nm, etc.

[0048] Optionally, the reflectivity of the first high-reflection grating 111b is 99.9%, and the reflectivity of the low-reflection grating 111c is 5% to 15%.

[0049] Optionally, when the continuous and quasi-continuous laser submodule 111 outputs quasi-continuous laser, or the quasi-continuous laser submodule 115 outputs quasi-continuous laser, the laser damage threshold of the first high-reflection grating 111b and the low-reflection grating 111c needs to be adapted to the pulse working state of the laser submodule. Specifically, the damage threshold is the maximum laser working power marked by the first high-reflection grating 111b and the low-reflection grating 111c, and the damage threshold is affected by the production process of the grating. In the pulse working state (that is, when the current source driving the output quasi-continuous laser is a pulse current source), the pulse peak power of the first semiconductor pump laser 111f cannot exceed the damage threshold, otherwise the grating may be burned.

[0050] Figure 6 This is a structural block diagram of the second continuous and quasi-continuous laser sub-module provided in an embodiment of the present application.

[0051] Optionally, combined Figure 6 As shown, the seed source module 11 further includes: a state detection component. The state detection component is configured to detect whether the seed source module 11 is working. The continuous and quasi-continuous laser submodule 111 includes a second beam combiner 111e; the state detection component includes a first photodetector 111g, and the first photodetector 111g is connected to the second beam combiner 111e.

[0052] In this embodiment, a first photodetector 111g is provided to detect whether an optical signal exists in the optical path of the second beam combiner 111e, so that it is possible to determine whether the continuous and quasi-continuous laser submodule 111 is working, that is, whether the seed source module 11 is working, according to whether the optical signal exists. If the seed source module 11 is working, the amplifier module 13 can be controlled to work. If the seed source module 11 is not working, controlling the amplifier module 13 to work may burn the amplifier module 13. Therefore, determining whether the continuous and quasi-continuous laser submodule 111 is working according to whether the optical signal exists can improve the safety of the system.

[0053] Optionally, the seed source module 11 further includes: a semiconductor refrigeration chip. Other components in the seed source module 11 are all arranged on the semiconductor refrigeration chip. In this way, the temperature of other components in the seed source module 11 can be regulated by using the semiconductor refrigeration chip.

[0054] Specifically, the first high-reflection grating 111b, the low-reflection grating 111c, the first gain fiber 111d, the second beam combiner 111e and the first semiconductor pump laser 111f are arranged on the semiconductor refrigeration chip. When the state detection element includes the first photodetector 111g, the first photodetector 111g is also arranged on the semiconductor refrigeration chip.

[0055] Figure 7 This is a structural block diagram of the first nanosecond laser submodule provided in an embodiment of the present application.

[0056] Optionally, combined Figure 7As shown, the nanosecond laser submodule 112 is configured to output nanosecond laser; the nanosecond laser submodule 112 includes: a single-mode semiconductor laser 112a, a first optical isolator 112b, a first wavelength division multiplexer 112c, a second gain fiber 112d and a second optical isolator 112e, and a second semiconductor pump laser 112f, which are sequentially arranged along the optical axis direction; the single-mode semiconductor laser 112a is configured to be driven by a pulse current source to output a seed laser; the first optical isolator 112b is configured to resist reflected light in a subsequent optical path of the first optical isolator 112b; the second gain fiber 112d is configured to provide laser gain; the second optical isolator 112e is configured to resist the second optical isolator 112 e; the second semiconductor pump laser 112f is configured to output a second pump laser to the second gain fiber 112d; the second pump laser output by the second semiconductor pump laser 112f is coupled to the second gain fiber 112d through the first wavelength division multiplexer 112c; wherein, the single-mode semiconductor laser 112a outputs a seed laser, the seed laser enters the second gain fiber 112d after passing through the first optical isolator 112b, the second pump laser output by the second semiconductor pump laser 112f is coupled to the seed laser to form a coupled laser, and the second pump laser, the seed laser and the coupled laser pass through the second optical isolator 112e along the second gain fiber 112d to output nanosecond laser.

[0057] In this embodiment, a pulse current source with adjustable output current repetition frequency and pulse width is used to drive the single-mode semiconductor laser 112a to output the seed laser, so that the repetition frequency and pulse width of the seed laser can be tunable. In addition, the second semiconductor pump laser 112f provides pump power to the second pump laser, and the laser gain is provided through the second gain fiber 112d, so that the initial laser output by the seed source module 11 is a nanosecond laser.

[0058] Specifically, the central wavelength of the laser output by the nanosecond pulse laser submodule depends on the central wavelength of the laser output by the single-mode semiconductor laser 112a, and can be optionally set to 1030nm, 1064nm, etc.

[0059] Exemplarily, the single-mode semiconductor laser 112 a is a butterfly package single-mode semiconductor laser.

[0060] Optionally, the wavelength of the second pump laser is between 940 nm and 980 nm.

[0061] Specifically, the power of the nanosecond laser output by the nanosecond laser submodule 112 can be adjusted in the range of 0 W to 100 W, the frequency can be adjusted in the range of 10 kHz to 3000 kHz, and the pulse width can be adjusted in the range of 5 ns to 200 ns.

[0062] Figure 8This is a structural block diagram of the second nanosecond laser submodule provided in an embodiment of the present application.

[0063] Optionally, combined Figure 8 As shown, the seed source module 11 further includes: a state detection component. The state detection component is configured to detect whether the seed source module 11 is working. The nanosecond laser submodule 112 includes a second optical isolator 112e; the state detection component includes a sampling beam splitter 112g and a second photodetector 112h which are sequentially connected to the second optical isolator 112e; the sampling beam splitter 112g is configured to extract part of the initial laser output by the second optical isolator 112e to the second photodetector 112h.

[0064] In this embodiment, a second photodetector 112h is provided to detect whether there is an optical signal in the optical path of the second optical isolator 112e outputting the initial laser, so that it is possible to determine whether the nanosecond laser submodule 112 is working, that is, whether the seed source module 11 is working, based on whether the optical signal is present. If the seed source module 11 is working, the amplifier module 13 can be controlled to work. The problem of the amplifier module 13 burning out is reduced, and the safety of the system is improved.

[0065] Optionally, the splitting ratio of the sampling beam splitter 112g may be any ratio between 99:1 and 99.9:0.1.

[0066] Optionally, the seed source module 11 further includes: a semiconductor refrigeration chip. Other components in the seed source module 11 are all arranged on the semiconductor refrigeration chip. In this way, the temperature of other components in the seed source module 11 can be regulated by using the semiconductor refrigeration chip.

[0067] Specifically, the single-mode semiconductor laser 112a, the first optical isolator 112b, the first wavelength division multiplexer 112c, the second gain fiber 112d, the second optical isolator 112e and the second semiconductor pump laser 112f are arranged on the semiconductor refrigeration chip. When the state detection element includes the second photodetector 112h, the second photodetector 112h is also arranged on the semiconductor refrigeration chip.

[0068] Fig. 9 This is a structural block diagram of the first picosecond laser submodule provided in an embodiment of the present application.

[0069] Optionally, combined Fig. 9As shown, the picosecond laser submodule 113 is configured to output picosecond laser; the picosecond laser submodule 113 includes: a semiconductor saturable absorber mirror 113b, a second wavelength division multiplexer 113e, a third gain fiber 113d, a beam splitter 113f and a second high-reflection grating 113c arranged in sequence along the optical axis; the semiconductor saturable absorber mirror 113b and the second high-reflection grating 113c form a second resonant cavity 113a; the third gain fiber 113d is configured to provide laser gain; the beam splitter 113f includes a first branch optical path and a second branch optical path, and the first branch optical path is optically connected to the second high-reflection grating 113c; the picosecond laser submodule 113 also includes: a pulse selector 113g and a third optical isolator 113h connected in sequence to the second branch optical path; a third semiconductor pump laser 113i, and the third semiconductor pump laser 113i is configured to output a third pump laser to the third gain fiber 113c 13d; the third pump laser output by the third semiconductor pump laser 113i is coupled to the third gain fiber 113d through the second wavelength division multiplexer 113e; the beam splitter 113f is configured to divide the third pump laser in the second resonant cavity 113a into a first sub-laser and a second sub-laser, the first sub-laser is configured to resonate in the second resonant cavity 113a, and the second sub-laser is configured to form an initial laser; wherein, the third semiconductor pump laser 113i outputs the third pump laser, the third pump laser is coupled to the third gain fiber 113d through the second wavelength division multiplexer 113e, the third pump laser is divided by the beam splitter 113f into a first sub-laser via the first branch optical path and a second sub-laser via the second branch optical path, the first sub-laser resonates in the second resonant cavity 113a, the second sub-laser is output and passes through the pulse selector 113g and the third optical isolator 113h to output picosecond laser.

[0070] In this embodiment, the third semiconductor pump laser 113i is driven by current to provide a third pump current, thereby obtaining laser gain, so that the initial laser output by the seed source module 11 is picosecond laser.

[0071] Specifically, the semiconductor saturable absorber mirror 113b is a laser mode locking and feedback device, which is used to realize the picosecond laser pulse operation of the module. The second wavelength division multiplexer 113e, the third gain fiber 113d and the beam splitter 113f are sequentially arranged in the second resonant cavity 113a. The pulse selector 113g is a commercial high-speed optical modulation device that can adjust the repetition frequency of the output laser within a certain range.

[0072] Specifically, the power of the picosecond laser output by the picosecond laser submodule 113 can be adjusted in the range of 0 W to 50 W, the repetition frequency can be adjusted in the range of 1 kHz to 30 MHz, and the pulse width is preset to a fixed value within the range of 7 ps to 1000 ps.

[0073] Fig.10This is a structural block diagram of the second picosecond laser sub-module provided in an embodiment of the present application.

[0074] Optionally, combined Fig.10 As shown, the seed source module 11 further includes: a state detection member. The state detection member is configured to detect whether the seed source module 11 is working. The picosecond laser submodule 113 includes a second high-reflection grating 113c; the state detection member includes a third photodetector 113j, and the third photodetector 113j is connected to the second high-reflection grating 113c.

[0075] In this embodiment, a third photodetector 113j is provided to detect whether there is an optical signal in the optical path of the second high-reflection grating 113c projecting the initial laser, so that it is possible to determine whether the picosecond laser submodule 113 is working, that is, whether the seed source module 11 is working, based on whether the optical signal is present. If the seed source module 11 is working, the amplifier module 13 can be controlled to work. The problem of the amplifier module 13 burning out is reduced, and the safety of the system is improved.

[0076] Optionally, the reflectivity of the second high-reflection grating 113c is greater than 90%, and the preset reflection center wavelength can be selected as 1030nm, 1064nm, etc. In this way, part of the light projected by the second high-reflection grating 113c will be detected by the third photodetector 113j, so as to determine whether the seed source module 11 is working.

[0077] Specifically, when the third photodetector 113j detects an optical signal, it sends a pulse trigger signal to the pulse selector 113g.

[0078] Optionally, the seed source module 11 further includes: a semiconductor refrigeration chip. Other components in the seed source module 11 are all arranged on the semiconductor refrigeration chip. In this way, the temperature of other components in the seed source module 11 can be regulated by using the semiconductor refrigeration chip.

[0079] Specifically, the semiconductor saturable absorber mirror 113b, the second wavelength division multiplexer 113e, the third gain fiber 113d, the beam splitter 113f, the second high reflection grating 113c, the pulse selector 113g and the third optical isolator 113h are arranged on the semiconductor refrigeration chip. In the case where the state detection element includes the third photodetector 113j, the second photodetector 112h is also arranged on the semiconductor refrigeration chip.

[0080] Fig.11 This is a schematic diagram of the amplifier submodule structure provided in an embodiment of the present application.

[0081] Optionally, combined Figure 4 and Fig.11As shown, the amplifier module 13 includes: one or more amplifier submodules; the amplifier submodule includes a light inlet and a light outlet; in the case where the amplifier module 13 includes multiple amplifier submodules, the multiple amplifier submodules are connected in sequence, and the light inlet of the amplifier submodule is connected in sequence to the light outlet of the previous amplifier submodule; the amplifier submodule includes: an isolation filter 131 and a fourth gain fiber 132 arranged in sequence along the optical axis. The isolation filter 131 is configured to filter out clutter in the laser entering from the light inlet and resist reflected light in the subsequent optical path of the isolation filter 131. The amplifier submodule also includes: a third beam combiner 133 and a fourth semiconductor pump laser 134. The number of the fourth semiconductor pump laser 134 is one or more; the fourth pump laser output by the fourth semiconductor pump laser 134 is coupled to the fourth gain fiber 132 through the third beam combiner 133.

[0082] In this embodiment, the initial laser output by the seed source module 11 enters from the light inlet of the first amplifier submodule, is amplified by the amplifier module 13 to form the target laser, and is output from the light outlet of the last amplifier submodule.

[0083] Exemplarily, the number of amplifier submodules can be increased or decreased according to the power of the target laser to be output. Taking the amplification process of an amplifier submodule as an example, the initial laser enters from the light inlet of the amplifier submodule, enters the isolation filter 131 to filter out the clutter in the initial laser, propagates to the fourth gain fiber 132, and couples with the fourth pump laser to achieve amplification of the initial laser by a single amplifier submodule. If multiple amplifier submodules are required, each amplifier submodule is used in turn to amplify the initial laser.

[0084] Specifically, the center wavelength of the output laser of each laser submodule should be consistent, such as 1064nm, 1030nm. This is to allow the initial laser to pass through the isolation filter in the amplifier submodule. The isolation filter is equipped with a coated lens inside, and its transmission laser center wavelength has a certain range. Lasers beyond the range cannot pass through. Generally, the light transmission range of commercial laser coated lenses is within 10nm, such as 1064nm±5nm, or 1030nm±5nm. If the center wavelengths of the output lasers of each laser submodule are inconsistent, some of the light output by the laser submodules will not pass through.

[0085] Continue to combine Figure 4As shown, in the example given in the embodiment of the present application, the amplifier module 13 includes three amplifier submodules, namely, a first amplifier submodule 135, a second amplifier submodule 136, and a third amplifier submodule 137. The first amplifier submodule 135, the second amplifier submodule 136, and the third amplifier submodule 137 are sequentially connected through optical fibers, and the third amplifier submodule 137 is responsible for the output of the target laser. The initial laser is amplified by the first amplifier submodule 135, the second amplifier submodule 136, and the third amplifier submodule 137 in sequence to form a target laser.

[0086] Specifically, the number of pump arms of the third beam combiner 133 provided in the embodiment of the present application is determined according to the number of fourth semiconductor pump lasers 134 , that is, one fourth semiconductor pump laser 134 corresponds to one pump arm.

[0087] Optionally, in the amplifier sub-modules connected in sequence, the fiber core diameters of the fourth gain fibers 132 increase in sequence.

[0088] Specifically, combined Figure 4 As shown, the core diameter of the fourth gain fiber 132 in each amplifier submodule should not be less than the core diameter of the fourth gain fiber 132 in the previous amplifier submodule, and the core diameter of the fourth gain fiber 132 in the first amplifier submodule (i.e., the first amplifier submodule 135) should not be less than the core diameter of the fiber at the output end of the first combiner 12. For example, the core diameter of the fiber at the output end of the first combiner 12 is 10μm, and the core diameters of the fourth gain fiber 132 in the first to third amplifier submodules (i.e., the first amplifier submodule 135, the second amplifier submodule 136, and the third amplifier submodule 137) are 12μm, 20μm, and 25μm, respectively. This is to avoid that when the optical fiber with a thicker core is directly fused with the optical fiber with a thinner core under the same numerical aperture, when the laser enters the thinner core optical fiber from the thick core optical fiber, there will be laser leakage from the fault where the core suddenly changes, and the large leakage light power will ignite the optical fiber at the leakage point, causing the laser to burn.

[0089] Optionally, when there are multiple fourth semiconductor pump lasers 134, the central wavelength of each fourth semiconductor pump laser 134 is different. In this way, it is convenient to control the working state of the fourth semiconductor pump laser 134 to provide fourth pump lasers with different pump powers.

[0090] For example, in combination Fig.11 As shown, each amplifier submodule includes two fourth semiconductor pump lasers 134 , and the central wavelengths of the two fourth semiconductor pump lasers 134 are 915 nm and 976 nm respectively.

[0091] Optionally, the fourth gain fiber 132 uses a double-clad ytterbium-doped gain fiber with a high pump light absorption coefficient, the absorption coefficient of the 915nm pump light should be in the range of 2dB / m to 5dB / m, and the length of the fourth gain fiber 132 does not exceed 6m.

[0092] Specifically, different types of lasers in the related art have different requirements for fiber length and gain, which is an important reason why these types of lasers in the related art cannot coexist. The embodiment of the present application provides a compatible solution. The reasons for achieving compatibility are as follows: Under certain conditions, the more pump light is absorbed, the higher the laser output power the laser can provide, and the greater the heat generated by the gain fiber.

[0093] For high-power continuous and quasi-continuous fiber lasers, low-absorption ytterbium-doped double-clad gain fiber is often used in related technologies. Its absorption coefficient for 915nm pump light is about 0.4dB / m, so that the heat generation of the fiber per unit length is low, and the heat dissipation area can be increased by lengthening the gain fiber. However, if the fiber length is too long, the Raman scattered light gain will also increase, affecting the laser output. The embodiment of the present application proposes that for such lasers, the gain fiber length is about 40m when using 915nm semiconductor laser pumping, which can take into account both laser output power and heat dissipation. When using 976nm semiconductor laser pumping, the gain fiber length is about 20m, which can take into account both laser output power and heat dissipation.

[0094] For nanosecond and picosecond pulsed lasers, the high-gain ytterbium-doped double-clad gain fiber commonly used in the related art has an absorption coefficient of about 3.5dB / m for 915 nm pump light. Because the peak power of the pulsed light is relatively high, the increase in the gain fiber length is more likely to cause stimulated Raman scattering and self-oscillation, which endanger the safety of laser operation, and the fiber with a high absorption coefficient can be used shorter. The embodiment of the present application proposes that for such lasers, the gain fiber length is about 4m when using a 915nm semiconductor laser pump, which can take into account both the laser output power and the reduction of Raman scattered light gain. When using a 976nm semiconductor laser pump, the gain fiber length is about 2m, which can take into account both the laser output power and the reduction of Raman scattered light gain.

[0095] The embodiment of the present application proposes that for high-power continuous and quasi-continuous fiber lasers, a high-gain ytterbium-doped double-clad gain fiber is used instead, and a 915nm and 976nm fourth semiconductor pump laser 134 is used to jointly pump the gain fiber. The gain fiber length can be reduced to about 6m at the expense of the laser amplifier pump light absorption efficiency and the decrease in the fiber heat dissipation surface area.

[0096] The embodiments of the present application propose that, for nanosecond and picosecond pulse lasers, a pulsed ytterbium-doped double-clad gain fiber is used, and a 915nm semiconductor laser is used to pump the gain fiber, so that the fiber length can be increased to about 6m at the expense of the single pulse energy of the laser pulse.

[0097] In this way, by setting the length of the fourth gain fiber 132 in the amplifier module 13 to be no more than 6m and using the fourth semiconductor pump laser 134 with a central wavelength of 915nm and 976nm, it is achieved that these types of lasers are compatible with various laser sub-modules, gain fibers of the amplifier module 13, and pumping methods while ensuring laser output.

[0098] Specifically, when the initial laser type output by the seed source module 11 is a quasi-continuous laser, that is, when the continuous and quasi-continuous laser sub-module 111 outputs a quasi-continuous laser or the quasi-continuous laser sub-module 115 is in operation, all fourth semiconductor pump lasers 134 in the amplifier module 13 should adopt a pulse operating mode, and their pulse operating states should be synchronized in time with the optical pulses of the output quasi-continuous laser.

[0099] Optionally, combined Figure 4 As shown, the control module 14 includes: a laser main control submodule 141 and a power drive submodule 142. The laser main control submodule 141 is connected to the seed source module 11 and the power drive submodule 142 through a signal line (combined with Figure 4 As shown by the dashed arrow in the middle, the laser main control submodule 141 is configured to control the seed source module 11 and the power drive submodule 142. The power drive submodule 142 is connected to the amplifier module 13 and the seed source module 11 through a power line and a signal line (combined with Figure 4 As shown by the dashed arrow in the figure, the power driving submodule 142 is configured to supply energy to the amplifier module 13 and the seed source module 11, and to control the operating current and operating temperature of the amplifier module 13 and the seed source module 11.

[0100] The present application provides a specific embodiment of a tunable fiber laser 1, which is as follows: The amplifier module 13 adopts a multi-stage structure with three amplifier submodules. The first-stage amplifier submodule (i.e., the first amplifier submodule, the output end of the first beam combiner 12 is connected to the light inlet of the first-stage amplifier submodule) uses a 915nm pumped 30W fourth semiconductor pump laser 134, and a 976nm pumped 27W fourth semiconductor pump laser 134. The second-stage amplifier submodule (i.e., the second amplifier submodule, the light outlet of the first amplifier submodule is connected to the light inlet of the second amplifier submodule) uses a 915nm pumped 70W fourth semiconductor pump laser 134, and a 976nm pumped 60W fourth semiconductor pump laser 134. The third-stage amplifier submodule (i.e., the third amplifier submodule, the light outlet of the second amplifier submodule is connected to the light inlet of the third-stage amplifier submodule) uses two 915nm pumped 170W fourth semiconductor pump lasers 134, and two 976nm pumped 140W fourth semiconductor pump lasers 134.

[0101] Fig.12 A schematic diagram of parameters of a tunable fiber laser outputting continuous laser light provided in an embodiment of the present application. Fig.12 (a) is a schematic diagram of the power of the continuous laser output by the tunable fiber laser 1. Fig.12 (b) is a schematic diagram of the spectrum of the continuous laser output by the tunable fiber laser 1.

[0102] When the continuous and quasi-continuous laser submodule 111 is turned on to output continuous laser, or the continuous laser submodule 114 is turned on to output continuous laser, the fourth semiconductor pump laser 134 in the control amplifier module 13 is all turned on. The average power of the laser output by the tunable fiber laser 1 is 353W, the central wavelength is 1063.9nm, and the power is as follows: Fig.12 As shown in (a), the spectrum is Fig.12 As shown in (b).

[0103] Fig.13 A schematic diagram of parameters of a tunable fiber laser outputting quasi-continuous laser provided in an embodiment of the present application. Fig.13 (a) is a schematic diagram of the power of the quasi-continuous laser output by the tunable fiber laser 1. Fig.13 (b) is a schematic diagram of the spectrum of the quasi-continuous laser output by the tunable fiber laser 1. Fig.13 (c) is a schematic diagram of a pulse sequence of quasi-continuous laser output by the tunable fiber laser 1.

[0104] When the continuous and quasi-continuous laser submodule 111 is turned on to output quasi-continuous laser, or the quasi-continuous laser submodule 115 is turned on to output quasi-continuous laser, the continuous and quasi-continuous laser submodule 111 or the quasi-continuous laser submodule 115 is set to output light with a duty cycle of 10%, a repetition rate of 10 Hz, and a pulse width of 50 ms, and the fourth semiconductor pump laser 134 in the control amplifier module 13 is fully turned on and maintained in a pulse working state synchronized with the laser submodule. The peak power of the output light pulse of the tunable fiber laser 1 is 350 W, the duty cycle is 10%, the repetition rate is 10 Hz, and the pulse width is 50 ms. The average power of the output laser is 35 W, and the central wavelength is 1064.2 nm. The power is as follows: Fig.13 As shown in (a), the spectrum is Fig.13 As shown in (b), the pulse sequence is Fig.13 As shown in (c).

[0105] Fig.14 A schematic diagram of parameters of a tunable fiber laser outputting nanosecond lasers provided in an embodiment of the present application. Fig.14 (a) is a schematic diagram of the power of the nanosecond laser output by the tunable fiber laser 1. Fig.14 (b) is a schematic diagram of the spectrum of nanosecond laser output by tunable fiber laser 1. Fig.14 (c) is a schematic diagram of the pulse sequence of nanosecond laser output by the tunable fiber laser 1. Fig.14 (d) is a schematic diagram of the pulse width of nanosecond laser output by the tunable fiber laser 1.

[0106] When the nanosecond laser submodule 112 is turned on to output nanosecond laser, the 915nm fourth semiconductor pump laser 134 in the control amplifier module 13 is turned on. The average power of the laser output by the tunable fiber laser 1 is 100.4W, the central wavelength is 1062.88nm, the pulse width is 11ns, and the repetition frequency is 3000kHz. Fig.14 As shown in (a), the spectrum is Fig.14 As shown in (b), the pulse sequence is Fig.14 As shown in (c), the pulse width is Fig.14 As shown in (d).

[0107] Fig.15 A schematic diagram of parameters of a tunable fiber laser outputting picosecond lasers provided in an embodiment of the present application. Fig.15 (a) is a schematic diagram of the power of the picosecond laser output by the tunable fiber laser 1. Fig.15 (b) is a schematic diagram of the spectrum of picosecond laser output by tunable fiber laser 1. Fig.15 (c) is a schematic diagram of the pulse sequence of picosecond laser output by the tunable fiber laser 1. Fig.15(d) is a schematic diagram of the pulse width of the picosecond laser output by the tunable fiber laser 1.

[0108] When the picosecond laser submodule 113 is turned on to output picosecond laser, the 915nm fourth semiconductor pump laser 134 in the control amplifier module 13 is turned on. The average power of the laser output by the tunable fiber laser 1 is 31.8W, the central wavelength is 1062.7nm, the pulse width is 20.2ps, and the repetition frequency is 18.5MHz. Fig.15 As shown in (a), the spectrum is Fig.15 As shown in (b), the pulse sequence is Fig.15 As shown in (c), the pulse width is Fig.15 As shown in (d).

[0109] Fig.16 A schematic flow chart of a control method for a tunable fiber laser provided in an embodiment of the present application.

[0110] Corresponding to the above-mentioned embodiment of the tunable fiber laser 1, the present application also provides an embodiment of a control method for the tunable fiber laser 1. The control method for the tunable fiber laser 1 is used for the tunable fiber laser 1 as in any one of the above-mentioned embodiments, and the execution body of the method can be the control module 14, combined with Fig.16 As shown, the control method for the tunable fiber laser 1 includes steps S1 to S5, which are specifically as follows: Step S1, obtaining target laser parameter information.

[0111] In this step, the laser main control submodule 141 in the control module 14 obtains the target laser parameter information input by the user, such as the type and power of the target laser input by the user.

[0112] Optionally, the target laser parameter information includes the type, power, repetition rate and pulse width of the target laser.

[0113] Step S2, determining the seed source operating parameters and amplifier operating parameters corresponding to the target laser parameter information.

[0114] Specifically, according to the type of target laser in the target laser parameter information, the laser submodule that needs to work is determined, that is, which laser submodule the seed source working parameter represents needs to work, and the working parameters required by the laser submodule, such as current, repetition rate and pulse width, etc. In addition, according to the type of target laser selected by the user, the corresponding amplifier module 13 parameter configuration scheme is referred to to form the amplifier working parameters.

[0115] Step S3, controlling the seed source module 11 to operate according to the seed source operating parameters.

[0116] In this step, the corresponding laser submodule is driven to work through the power line of the power driver submodule 142, and the information such as current, repetition rate and pulse width are loaded to the laser submodule through the signal line of the power driver submodule 142.

[0117] Step S4, detecting the working status of the seed source module 11.

[0118] In this step, by obtaining the presence or absence of the optical signal detected by the status detection component, it is determined whether the working status of the seed source module 11 is working, so that when the working status of the seed source module 11 is working, the amplifier module 13 is controlled to work to reduce the problem of laser burning.

[0119] Specifically, the photoelectric detector is used to detect whether the corresponding seed source module 11 has been operated.

[0120] Step S5: When the seed source module 11 is in working state, the amplifier module 13 is controlled to work according to the amplifier working parameters.

[0121] The control method for the tunable fiber laser 1 provided in the embodiment of the present application is used to control the operation of the seed source module 11 and the amplifier module 13 according to the target laser parameter information input by the user, so as to output the target laser.

[0122] Specifically, since the parameters of the amplifier module 13 required for the optical amplification process of different types of laser sub-modules are obviously different, for example, the continuous and quasi-continuous laser sub-modules 111 need to control the heating of the amplifier module 13, the amplification of the nanosecond laser sub-module 112 requires that the amplifier module 13 cannot self-oscillate during operation, and the amplification of the picosecond laser sub-module 113 requires that the amplifier module 13 cannot self-oscillate and pulse broaden during operation, different requirements are put forward for the parameter setting of the amplifier module 13.

[0123] Exemplarily, the laser main control submodule 141 receives external input of laser parameter setting instructions, such as light type, laser frequency, pulse width, light power, etc., and parses and determines the corresponding seed source working parameters and amplifier working parameters. The seed source of the corresponding working state is turned on according to the seed source working parameters. The amplifier working parameters are sent to the power driver submodule 142, such as the operating current and operating temperature instructions of each amplifier submodule. The power driver submodule 142 turns on each amplifier submodule in sequence according to the amplifier working parameters, so that the tunable fiber laser 1 emits light. During operation, the control of the specific light emission parameters is realized by relying on the instructions loaded by the internal drive circuit of the seed source module 11, the light output power is controlled by relying on the current value of the fourth semiconductor pump laser 134, and the switching of the light emission type is realized by relying on the switching of the laser submodule inside the seed source module 11.

[0124] Exemplarily, taking the case where each amplifier submodule includes two fourth semiconductor pump lasers 134, and the central wavelengths of the two fourth semiconductor pump lasers 134 are 915 nm and 976 nm respectively, the embodiment of the present application comprehensively considers the above requirements and proposes a compatible amplifier module 13 parameter configuration scheme as follows: When the continuous and quasi-continuous laser submodule 111 is started, the fourth semiconductor pump laser 134 with a central wavelength of 915 nm and 976 nm in each amplifier submodule can be turned on simultaneously to provide a pump laser with maximum power.

[0125] When the nanosecond or picosecond laser submodule 113 is used, only the fourth semiconductor pump laser 134 with a central wavelength of 915 nm in each amplifier submodule is turned on to provide pump laser.

[0126] Specifically, the principle of the parameter configuration scheme of the amplifier module 13 is as follows: The absorption spectrum of the double-clad ytterbium-doped gain fiber corresponds to a spectral range of 880nm to 1030nm. Within this range, there are two significant absorption peaks, namely 915nm and 976nm. Compared with the 915nm absorption peak, the absorption cross-sectional area at 976nm is about 3 times more than the absorption cross-sectional area at 915nm. This means that under the same fiber length and absorption coefficient, the absorption efficiency of 976nm light waves in double-clad ytterbium-doped gain fibers is 2 to 3 times that of 915nm light waves. Such a huge difference in absorption efficiency leads to the fact that for gain fibers of the same specifications and length, using 976nm semiconductor laser pumping can obtain a higher amplifier gain than 915nm. In addition, the higher the pump light absorption, the higher the gain, while stimulated Raman scattering is positively correlated with gain and fiber length, and self-oscillation is positively correlated with gain. That is, the greater the gain, the greater the stimulated Raman scattering and self-oscillation.

[0127] For the continuous and quasi-continuous laser submodule 111, the laser power is output relatively smoothly and the peak power is not high. The fourth semiconductor pump laser 134 with a central wavelength of 915nm and a central wavelength of 976nm is used in combination to provide a fourth pump laser with a higher power, thereby providing as much gain as possible and increasing the output optical power.

[0128] For the nanosecond or picosecond laser submodule 113, the peak power of the pulsed light is relatively high, and it is more prone to stimulated Raman scattering and self-oscillation, which endanger the safety of the laser operation. Compared with using 976nm pumping, using the fourth semiconductor pump laser 134 with a central wavelength of 915nm will reduce the gain, but it can suppress stimulated Raman scattering and self-oscillation and protect the safety of the laser.

[0129] Optionally, after step S5, the method further includes: Step S6: when the target laser parameter information changes, the seed source module 11 and the amplifier module 13 are turned off, and the target laser parameter information is acquired and updated.

[0130] In this embodiment, when the target laser parameter information changes, it indicates that the laser type, power and other information currently required by the user have changed, so it is necessary to re-change the operation of the laser sub-module in the seed source module 11, and to shut down the amplifier module 13 to reduce laser burnout.

[0131] It should be noted that those skilled in the art will easily think of other embodiments of the present application after considering the specification and practicing the application disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary technical means in the art that are not disclosed in the present application. The specification and examples are only regarded as exemplary, and the true scope of the present application is indicated by the claims.

[0132] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A tunable fiber laser, characterized in that: include: A seed source module (11), wherein the seed source module (11) is configured to output an initial laser; The seed source module (11) comprises a plurality of continuous and quasi-continuous laser submodules (111), nanosecond laser submodules (112) and picosecond laser submodules (113); the type of the initial laser corresponds to the type of the laser submodule included in the seed source module (11); A first beam combiner (12); an amplifier module (13), wherein the seed source module (11) and the amplifier module (13) are connected via the first beam combiner (12); the amplifier module (13) is configured to amplify the initial laser to form a target laser; The control module (14) is respectively connected to the seed source module (11) and the amplifier module (13) for communication, so as to control the type of laser output by the seed source module (11) and the working state of the amplifier module (13).

2. The tunable fiber laser according to claim 1, characterized in that: The continuous and quasi-continuous laser submodule (111) is configured to output continuous laser and / or quasi-continuous laser; the continuous and quasi-continuous laser submodule (111) comprises: A second beam combiner (111e), a first high-reflection grating (111b), a first gain optical fiber (111d), and a low-reflection grating (111c) are sequentially arranged along the optical axis direction; The first high-reflection grating (111b) and the low-reflection grating (111c) form a first resonant cavity (111a); The first gain fiber (111d) is configured to provide laser gain; The continuous and quasi-continuous laser submodule (111) further comprises: A first semiconductor pump laser (111f) is configured to output a first pump laser; the first pump laser is coupled to the first gain fiber (111d) through the second beam combiner (111e); the number of the first semiconductor pump lasers (111f) is one or more; when the number of the first semiconductor pump lasers (111f) is multiple, multiple beams of the first pump lasers output by the multiple first semiconductor pump lasers (111f) are combined into a total pump laser through the second beam combiner (111e) and coupled to the first gain fiber (111d); The first semiconductor pump laser (111f) is driven to output the first pump laser, the first pump laser enters the first resonant cavity (111a) through the first high-reflection grating (111b), the first pump laser oscillates in the first resonant cavity (111a) along the first gain optical fiber (111d), and part of the first pump laser outputs the first resonant cavity (111a) through the low-reflection grating (111c) to output the continuous laser and / or the quasi-continuous laser.

3. The tunable fiber laser according to claim 1, characterized in that: The nanosecond laser submodule (112) is configured to output nanosecond laser; the nanosecond laser submodule (112) comprises: A single-mode semiconductor laser (112a), a first optical isolator (112b), a first wavelength division multiplexer (112c), a second gain optical fiber (112d) and a second optical isolator (112e), and a second semiconductor pump laser (112f) are sequentially arranged along the optical axis direction; The single-mode semiconductor laser (112a) is configured to be driven by a pulse current source to output a seed laser; The first optical isolator (112b) is configured to resist reflected light in a subsequent optical path of the first optical isolator (112b); The second gain fiber (112d) is configured to provide laser gain; The second optical isolator (112e) is configured to resist reflected light in a subsequent optical path of the second optical isolator (112e); The second semiconductor pump laser (112f) is configured to output a second pump laser to the second gain optical fiber (112d); the second pump laser output by the second semiconductor pump laser (112f) is coupled to the second gain optical fiber (112d) through the first wavelength division multiplexer (112c); The single-mode semiconductor laser (112a) outputs the seed laser, the seed laser passes through the first optical isolator (112b) and enters the second gain optical fiber (112d), the second pump laser output by the second semiconductor pump laser (112f) is coupled to the seed laser to form a coupled laser, and the second pump laser, the seed laser and the coupled laser pass through the second optical isolator (112e) along the second gain optical fiber (112d) to output the nanosecond laser.

4. The tunable fiber laser according to claim 1, characterized in that: The picosecond laser submodule (113) is configured to output picosecond laser; the picosecond laser submodule (113) comprises: A semiconductor saturable absorption mirror (113b), a second wavelength division multiplexer (113e), a third gain optical fiber (113d), a beam splitter (113f) and a second high-reflection grating (113c) are sequentially arranged along the optical axis direction; The semiconductor saturable absorption mirror (113b) and the second high-reflection grating (113c) form a second resonant cavity (113a); The third gain fiber (113d) is configured to provide laser gain; The beam splitter (113f) comprises a first branch light path and a second branch light path, the first branch light path being optically connected to the second high-reflection grating (113c); The picosecond laser submodule (113) further includes: A pulse selector (113g) and a third optical isolator (113h) connected in sequence to the second branch optical path; a third semiconductor pump laser (113i), the third semiconductor pump laser (113i) being configured to output a third pump laser to the third gain optical fiber (113d); the third pump laser output by the third semiconductor pump laser (113i) is coupled to the third gain optical fiber (113d) through the second wavelength division multiplexer (113e); The beam splitter (113f) is configured to split the third pump laser in the second resonant cavity (113a) into a first sub-laser and a second sub-laser, the first sub-laser being configured to resonate in the second resonant cavity (113a), and the second sub-laser being configured to form the initial laser; The third semiconductor pump laser (113i) outputs the third pump laser, the third pump laser is coupled to the third gain fiber (113d) through the second wavelength division multiplexer (113e), the third pump laser is divided by the beam splitter (113f) into the first sub-laser via the first branch optical path and the second sub-laser via the second branch optical path, the first sub-laser resonates in the second resonant cavity (113a), the second sub-laser is output and passes through the pulse selector (113g) and the third optical isolator (113h) to output the picosecond laser.

5. The tunable fiber laser according to any one of claims 1 to 4, characterized in that: The seed source module (11) further comprises: A status detection component configured to detect whether the seed source module (11) is working; The continuous and quasi-continuous laser submodule (111) comprises a second beam combiner (111e); the state detection component comprises a first photodetector (111g), and the first photodetector (111g) is connected to the second beam combiner (111e); The nanosecond laser submodule (112) comprises a second optical isolator (112e); the state detection element comprises a sampling beam splitter (112g) and a second photodetector (112h) connected to the second optical isolator (112e) in sequence; the sampling beam splitter (112g) is configured to extract a portion of the initial laser output by the second optical isolator (112e) to the second photodetector (112h); The picosecond laser submodule (113) comprises a second high-reflection grating (113c); the state detection component comprises a third photodetector (113j), and the third photodetector (113j) is connected to the second high-reflection grating (113c); And / or, a semiconductor refrigeration sheet, and other devices in the seed source module (11) are all arranged on the semiconductor refrigeration sheet.

6. The tunable fiber laser according to claim 1, characterized in that: The amplifier module (13) comprises: one or more amplifier sub-modules; The amplifier submodule includes a light inlet and a light outlet; In the case where the amplifier module (13) comprises a plurality of amplifier submodules, the plurality of amplifier submodules are connected in sequence, and the light inlet of the amplifier submodule is connected in sequence to the light outlet of the previous amplifier submodule; The amplifier submodule comprises: An isolation filter (131) and a fourth gain optical fiber (132) arranged in sequence along the optical axis; The isolation filter (131) is configured to filter out clutter in the laser light entering through the light inlet and to resist reflected light in a subsequent optical path of the isolation filter (131); The amplifier submodule further comprises: a third beam combiner (133) and a fourth semiconductor pump laser (134); The number of the fourth semiconductor pump lasers (134) is one or more; The fourth pump laser output by the fourth semiconductor pump laser (134) is coupled to the fourth gain optical fiber (132) through the third beam combiner (133).

7. The tunable fiber laser according to claim 6, characterized in that: When there are a plurality of fourth semiconductor pump lasers (134), the central wavelength of each of the fourth semiconductor pump lasers (134) is different.

8. The tunable fiber laser according to claim 6, characterized in that: In the amplifier submodules connected in sequence, the fiber core diameters of the fourth gain optical fibers (132) increase in sequence.

9. The tunable fiber laser according to claim 1, characterized in that: The control module (14) comprises: a laser main control submodule (141) and a power drive submodule (142); The laser main control submodule (141) is connected to the seed source module (11) and the power drive submodule (142) via a signal line, and the laser main control submodule (141) is configured to control the seed source module (11) and the power drive submodule (142); The power driving submodule (142) is connected to the amplifier module (13) and the seed source module (11) via a power line and a signal line. The power driving submodule (142) is configured to supply energy to the amplifier module (13) and the seed source module (11), and to control the operating current and operating temperature of the amplifier module (13) and the seed source module (11).

10. A control method for a tunable fiber laser, characterized in that: The control method for a tunable fiber laser is used for the tunable fiber laser according to any one of claims 1 to 9, and the control method for a tunable fiber laser comprises: S1, obtaining target laser parameter information; S2, determining the seed source operating parameters and amplifier operating parameters corresponding to the target laser parameter information; S3, controlling the seed source module (11) to operate according to the seed source operating parameters; S4, detecting the working state of the seed source module (11); S5, when the working state of the seed source module (11) is in operation, controlling the amplifier module (13) to operate according to the amplifier operating parameters.

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