A master amplifier and high peak value dual pulse fiber laser
By integrating active pump signal combiners and spatial isolators, the problems of peak power enhancement and pulse control in fiber lasers have been solved, resulting in a high-efficiency, high-peak-value dual-pulse fiber laser suitable for industrial processing and precision marking.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- WUHAN LEISHENG TECH CO LTD
- Filing Date
- 2025-08-06
- Publication Date
- 2026-05-29
AI Technical Summary
Existing fiber lasers suffer from problems such as low system integration, severe nonlinear effects, decreased beam quality, and difficulty in achieving narrow pulse width dual-pulse control using traditional electrical modulation when increasing peak power, resulting in unsatisfactory processing effects.
An integrated design of an active pump signal combiner, spatial isolator, beam expander lens group and reflector group is adopted. Combined with a high peak value dual-pulse fiber laser structure, through the optical path connection of seed source, isolator and amplification module, efficient pump light coupling and beam adjustment are achieved, nonlinear effects are reduced and pulse interval and peak ratio are controlled.
It achieves peak power >200kW and average power >300W output, reduces nonlinear effects, improves beam quality and processing accuracy, adapts to different ambient temperatures, and allows customers to adjust the beam themselves.
Smart Images
Figure CN224305155U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of fiber laser technology, specifically to a main amplifier and a high-peak-value dual-pulse fiber laser. Background Technology
[0002] Fiber lasers are widely used in industrial marking and cutting applications due to their flexible design, stability, and maintenance-free operation. Common types include continuous fiber lasers, Q-switched fiber lasers, and MOPA fiber lasers. In specialized applications such as precision marking and glass processing, where narrow pulse widths and high peak power are required, more expensive ultrafast lasers or solid-state lasers can be chosen. Alternatively, the peak power limitation of fiber lasers can be overcome to achieve the same processing effect. However, ultrafast and solid-state lasers are expensive, have lower power output compared to fiber lasers, and are more difficult to maintain. Fiber lasers, on the other hand, are favored by the market due to their stability and low cost.
[0003] Fiber lasers typically consist of one or more stages of amplification, with the last stage generally called the main amplifier. This stage can be adjusted freely depending on the application. Taking the MOPA fiber laser as an example, its typical structure is as follows: Figure 4 As shown, the focus here is on the main amplifier section, which is fabricated by fusing the MFA mode field adapter, active fiber, pump signal combiner, CPS cladding stripping region, and isolator separately. Its advantages include ease of operation, mass production, and convenient maintenance, with a peak power typically around 20kW. The main reason for the lower peak power is the low system integration and long fiber transmission path, leading to a series of nonlinear effects that limit further increases in peak power. Common methods to increase peak power include increasing the core diameter of the main amplifier fiber, but this sacrifices beam quality, or artificially shortening the connecting fibers between components. This makes splicing difficult and creates significant bottlenecks, limiting the peak power to around 100kW. Currently, there is also a method of spatially coupling the pump light to the active fiber. The advantage is higher peak power, reaching 250kW, but the disadvantages include significant coupling heat, difficulty in controlling the pump coupling angle, easy damage to the active fiber at the coupling point, difficulty in achieving high average power (rarely exceeding 200W), and high fabrication difficulty and cost.
[0004] In some cutting applications, especially with brittle materials, a dual-pulse configuration is used to reduce edge chipping. However, traditional electrical modulation struggles to control the pulse interval while maintaining an output pulse width within 10ns, resulting in unsatisfactory performance. Furthermore, controlling the height of the two pulses is difficult, causing the peak power of the amplified first pulse to far exceed that of the second pulse, negatively impacting the machining effect. Utility Model Content
[0005] To achieve the above objectives, this utility model provides the following technical solution:
[0006] On one hand, the main amplifier includes a water-cooled mounting plate and a first active optical fiber, an active pump signal combiner, a spatial isolator, a beam expander lens group, a reflector group, and a power meter arranged sequentially on the water-cooled mounting plate. The output optical fiber of the active pump signal combiner has a quartz end cap. A long tube aperture is provided between the reflector groups. The main amplifier is also provided with a window on the reflected output optical path of the reflector group.
[0007] Furthermore, the active pump signal combiner includes a copper housing, on which a copper substrate and a sapphire substrate are disposed. A passive signal fiber is disposed on the sapphire substrate. One end of the passive signal fiber is fused to a first active optical fiber, and the fusion point is located on the copper substrate. A tapered region and a cladding light stripping region are formed on the passive signal fiber. At the same time, at least one pump arm is fused to the passive signal fiber. The output end of the passive signal fiber is equipped with the quartz end cap.
[0008] Furthermore, the space isolator includes an outer shell, within which are disposed a strong magnetic ring, a first birefringent crystal, a Faraday rotator crystal, and a second birefringent crystal. The strong magnetic ring is used to provide a magnetic field for the Faraday rotator crystal, and the first birefringent crystal, the Faraday rotator crystal, and the second birefringent crystal are arranged in sequence along optical paths.
[0009] Furthermore, a heating ring is provided on the outside of the space isolator.
[0010] Furthermore, the beam-expanding lens group includes a first adjustable lens mount and a second adjustable lens mount, wherein a plano-concave lens is mounted on the first adjustable lens mount and a plano-convex lens is mounted on the second adjustable lens mount.
[0011] Furthermore, the reflector assembly includes a third adjustable mirror mount and a fourth adjustable mirror mount. A first reflector is mounted on the third adjustable mirror mount, and a second reflector is mounted on the fourth adjustable mirror mount. The window is located in the reflection direction of the second reflector, and the power meter is located in the transmission direction of the second reflector.
[0012] On the other hand, the high peak dual-pulse fiber laser includes a seed source, a 1*2 isolator, a 2*1 isolator, a first-stage amplification module, a second-stage amplification module, and the main amplifier, which are connected in sequence by optical paths.
[0013] The two outputs of the 1*2 isolator are respectively connected to a delay fiber and an acousto-optic modulator.
[0014] The two inputs of the 2*1 isolator are connected to the optical paths of the delay fiber and the acousto-optic modulator, respectively, and its output is connected to the optical path of the first-stage amplifier module.
[0015] The first-stage amplification module includes a third active optical fiber, a 980nm single-mode pump source, and a first wavelength division multiplexer connected in sequence, and a first online isolator is provided between the first-stage amplification module and the second-stage amplification module.
[0016] The secondary amplification module includes a second active optical fiber, a 915nm multimode pump source, and a pump signal combiner connected in sequence via optical paths. A second in-line isolator and a mode field adapter are provided between the secondary amplification module and the main amplifier.
[0017] Compared with the prior art, the technical solution of this application has the following beneficial effects:
[0018] 1. This utility model replaces the spatial pump coupling method with an integrated design of an active pump signal combiner, resulting in high average laser power, easy mass production, and low price. Furthermore, the use of an end cap and spatial isolator scheme, without any extra transmission fiber in the middle, makes it easier to achieve the amplifier output fiber length limit, achieving a similar effect to spatial coupling, further reducing nonlinear effects, and enabling peak power >200kW and average power >300W output.
[0019] 2. This utility model adopts a split beam expander lens group, which is convenient for customers to replace to match different galvanometer systems; it adopts a long tube aperture to protect the lens group, which greatly reduces the lens damage caused by defocusing during mirror material processing; it adds a reflector group, which makes it convenient for customers to adjust the actual beam direction to match the external structure, compensate for machining errors, and can also add an integrated power acquisition feedback system, which is convenient for power feedback compensation during high-precision processing.
[0020] 3. This utility model adopts a replaceable window plate to reduce further losses caused by operational errors of end customers; in cold weather areas such as the north, a heating ring can be selected to solve the problems of slow water circulation heating and easy damage to the machine during cold start. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the structure of this utility model;
[0022] Figure 2 This is a schematic diagram of the internal connection structure of the main amplifier in this utility model;
[0023] Figure 3 This utility model Figure 2 Schematic diagram of the connection structure of the active pump signal combiner;
[0024] Figure 4 This refers to the existing fiber laser structure.
[0025] In the diagram: 001, Seed source; 002, 1*2 isolator; 003, Delay fiber; 004, Acousto-optic modulator; 005, 2*1 isolator; 006, Third active fiber; 007, 980nm single-mode pump source; 008, Wavelength division multiplexer; 009, First in-line isolator; 010, Second active fiber; 011, 915nm multimode pump source; 012, Pump signal combiner; 013, Second in-line isolator; 014, Mode field adapter; 015, Main amplifier; 00, Water-cooled mounting plate; 10, Active pump signal combiner; 11, Cladding stripping region; 12, Tapered region; 13, Copper substrate. 14. First active optical fiber; 15. First pump arm; 16. Second pump arm; 17. Quartz end cap; 20. Spatial isolator; 21. Housing; 22. Strong magnet ring; 23. First birefringent crystal; 25. Second birefringent crystal; 24. Faraday rotator crystal; 30. First adjustable mirror mount; 40. Second adjustable mirror mount; 50. Third adjustable mirror mount; 70. Fourth adjustable mirror mount; 31. Plano-concave lens; 41. Plano-convex lens; 51. First reflecting mirror; 71. Second reflecting mirror; 60. Long tube aperture; 80. Power meter; 90. Window; 2. Copper housing; 4. Sapphire substrate; 6. Passive signal fiber. Detailed Implementation
[0026] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0027] Please see Figure 2 and 3 The main amplifier shown in this embodiment includes a water-cooled mounting plate 00 and, fixed on the water-cooled mounting plate 00, a first active optical fiber 14, an active pump signal combiner 10, a spatial isolator 20, a beam expander lens group, a reflector group, and a power meter 80 arranged sequentially. The output optical fiber of the active pump signal combiner 10 has a quartz end cap 17 to increase the light spot and reduce the surface power density at the output end. A long tube aperture 60 is provided between the reflector groups. A window 90 is also provided on the reflected output optical path of the main amplifier 015 located within the reflector group. The water-cooled mounting plate 00 is used to fix all components and provide heat dissipation. The active pump signal combiner 10 is used to couple the pump light to the first active optical fiber. The spatial isolator 20 is used to protect the entire amplifier and prevent backlighting from affecting amplification.
[0028] like Figure 3The active pump signal combiner 10 includes a copper housing 2, on which a copper substrate 13 and a sapphire substrate 4 are disposed. A passive signal fiber 6 is disposed on the sapphire substrate 4. One end of the passive signal fiber 6 is fused to a first active optical fiber 14, and the fusion point is located on the copper substrate 13. The copper substrate is used to ensure stability. A tapered region 12 and a cladding light stripping region 11 are formed on the passive signal fiber 6 to remove unwanted cladding light. Here, the cladding light stripping region is an optical fiber segment that has been etched or specially treated, and whose surface has been roughened. At the same time, the passive signal fiber 6 is also fused with at least one pump arm for connecting to a pump source. The pump arms shown in the figure are the first pump arm 15 and the second pump arm 16. The tapered region 12 is formed by bonding and sintering the pump fiber and the signal fiber to form a tapered structure, which efficiently couples the pump light to the passive signal fiber 6 and the first active fiber 14. The output end of the passive signal fiber 6 is equipped with the quartz end cap 17, which is used to increase the light spot and reduce the surface power density of the output end.
[0029] Alternatively, the copper substrate and the outer shell can be made into a single structure. In this embodiment, the sapphire substrate is embedded and installed into the copper outer shell. The sapphire substrate is relatively thin, approximately 1 mm thick, while the outer shell is thicker than the sapphire substrate. The copper outer shell has an overall width of 10 mm, a height of 6 mm, and a length of approximately 90 mm.
[0030] The space isolator 20 includes a housing 21. Inside the housing 21 are a strong magnetic ring 22, a first birefringent crystal 23, a Faraday rotator crystal 24, and a second birefringent crystal 25. The strong magnetic ring 22 provides a magnetic field to the Faraday rotator crystal 24. The first birefringent crystal 23, the Faraday rotator crystal 24, and the second birefringent crystal 25 are arranged sequentially in optical paths to isolate backlighting and protect the amplifier. The housing 21 supports and protects the internal components of the space isolator and provides mounting holes for fixing it to a water-cooled plate. The birefringent crystal separates incident light into linearly polarized light in two directions. The Faraday rotator crystal rotates the linearly polarized light by a certain angle.
[0031] In addition, the beam expander lens group includes a first adjustable lens mount 30 and a second adjustable lens mount 40. The first adjustable lens mount 30 and the second adjustable lens mount 40 are respectively equipped with a plano-concave lens 31 and a plano-convex lens 41. The lens mount can magnify the light spot to a preset size by adjusting the plano-concave lens 31 and the plano-convex lens 41.
[0032] To further explain, the reflector assembly includes a third adjustable mirror mount 50 and a fourth adjustable mirror mount 70. The third adjustable mirror mount 50 and the fourth adjustable mirror mount 70 respectively mount the first reflector 51 and the second reflector 71. The first reflector 51 reflects the light path by 90°, and the second reflector 71 reflects a small amount of light, such as 0.5%, to the power meter 80 for monitoring feedback. The remaining light is output through the window 90.
[0033] Additionally, the long tube aperture 60 is used to block stray light reflected from highly reflective materials; the window 90 is a replaceable structure to reduce losses due to operational errors; and a heating ring can be installed on the outside of the space isolator 20 to adapt to low-temperature environments.
[0034] In this embodiment, the high-peak-value dual-pulse fiber laser includes a seed source 001, a 1*2 isolator 002, a 2*1 isolator 005, a first-stage amplification module, a second-stage amplification module, and a main amplifier 015, which are connected in sequence via optical paths. The two outputs of the 1*2 isolator 002 are respectively connected to a delay fiber 003 and an acousto-optic modulator 004, which are used to split the signal light output from the seed source into two paths. The delay fiber achieves a time delay of the first path signal light by setting a specific length to control the dual-pulse interval. The acousto-optic modulator acts as an optical switch to intercept a specific pulse width of the second path signal light to achieve pulse width adjustment. The two inputs of the 2*1 isolator 005 are respectively connected to the optical paths of the delay fiber 003 and the acousto-optic modulator 004, which combine the two path signal lights into a dual-pulse signal with a specific interval, pulse width, and peak ratio, and output it to the first-stage amplification module.
[0035] The primary amplification module includes a third active optical fiber 006, a 980nm single-mode pump source 007, and a first wavelength division multiplexer 008 connected in sequence via optical paths. The 980nm single-mode pump source 007 provides pump energy, which is coupled to the third active optical fiber 006 via the first wavelength division multiplexer 008. The third active optical fiber 006 performs preliminary amplification of the dual-pulse signal under pump light excitation to ensure a high signal-to-noise ratio for low-power signals. A first in-line isolator 009 is provided between the primary amplification module and the secondary amplification module to block the backlight from the secondary amplification module and protect the primary amplification module for stable operation.
[0036] In addition, the secondary amplification module includes a second active optical fiber 010, a 915nm multimode pump source 011, and a pump signal combiner 012 connected in sequence via optical paths. The 915nm multimode pump source 011 outputs high-power pump light, which is injected into the second active optical fiber 010 through the pump signal combiner 012. The second active optical fiber 010 further amplifies the signal after the first-stage amplification, increasing the signal power. A second in-line isolator 013 and a mode field adapter 014 are provided between the secondary amplification module and the main amplifier 015. The second in-line isolator 013 prevents backlight interference from the main amplifier; the mode field adapter 014 enables matching connections of optical fibers with different core diameters, reducing losses.
[0037] The working principle of the above embodiments is as follows:
[0038] The seed source outputs an initial pulse with a set pulse width, which is split into two paths by a 1*2 isolator: the first path achieves time misalignment via a delay fiber, and the second path intercepts the pulse signal via an acousto-optic modulator. The two signals are combined by a 2*1 isolator to form a dual-pulse signal, which enters the first-stage amplification module. The pump light output from the 980nm single-mode pump source is coupled to the third active fiber via the first wavelength division multiplexer for preliminary signal amplification. The first in-line isolator blocks the return light, and the preliminarily amplified signal enters the second-stage amplification module. The high-power pump light output from the 915nm multimode pump source is injected into the second active fiber via a pump signal combiner, further increasing the signal power. The second in-line isolator protects the second-stage amplification module, and the mode field adapter is connected to the main amplifier after matching the fiber core diameter.
[0039] In the main amplifier, the signal output fiber to be amplified is fused to the first active fiber 14, and the pump source is fused to the first pump arm 15 and the second pump arm 16. The pump source injects pump light into the first active fiber 14 through the source pump signal combiner 10. The amplified signal light is output again through the first active fiber 10, and useless cladding light is stripped away. The signal light passes through a fiber less than 10cm long to the quartz end cap expander 17 and is slightly expanded. Then it passes through the spatial isolator 20 to be isolated and reflected back to the output. Then it passes through a beam-expanding lens group composed of a plano-concave lens and a plano-convex lens to magnify the light spot to 10mm. The appropriate beam expansion ratio is selected according to the usage requirements. After being reflected 90° by the first reflector 51, the light passes through the long tube aperture 60. About 0.5% of the light passes through the second reflector 71 and reaches the power meter 80 for optical rate monitoring and feedback. Most of the remaining light is reflected 90° by the second reflector 71 and output.
[0040] When processing highly reflective materials, the long tube aperture blocks some of the reflected stray light; in low-temperature environments, the external heating ring of the space isolator is activated to avoid damage from cold starts.
[0041] The entire workflow is now complete, and anything not described in detail in this specification is existing technology known to those skilled in the art.
[0042] It should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0043] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A main amplifier, characterized in that, The main amplifier (015) includes a water-cooled mounting plate (00) and a first active optical fiber (14), an active pump signal combiner (10), a spatial isolator (20), a beam expander lens group, a reflector group, and a power meter (80) arranged sequentially on the water-cooled mounting plate (00). The output optical fiber of the active pump signal combiner (10) has a quartz end cap (17). A long tube aperture (60) is provided between the reflector groups. The main amplifier (015) is also provided with a window (90) on the reflected output optical path of the reflector group.
2. The main amplifier according to claim 1, characterized in that: The active pump signal combiner (10) includes a copper shell (2), a copper substrate (13) and a sapphire substrate (4) on the copper shell (2), a passive signal fiber (6) on the sapphire substrate (4), one end of the passive signal fiber (6) is fused to the first active optical fiber (14), and the fusion point is located on the copper substrate (13). A tapered region (12) and a cladding light stripping region (11) are formed on the passive signal fiber (6). At the same time, at least one pump arm is fused to the passive signal fiber (6). The output end of the passive signal fiber (6) is equipped with the quartz end cap (17).
3. A main amplifier according to claim 1, characterized in that: The space isolator (20) includes an outer shell (21), in which a strong magnet ring (22), a first birefringent crystal (23), a Faraday rotator crystal (24), and a second birefringent crystal (25) are provided. The strong magnet ring (22) is used to provide a magnetic field for the Faraday rotator crystal (24). The first birefringent crystal (23), the Faraday rotator crystal (24), and the second birefringent crystal (25) are arranged in sequence along the optical path.
4. A main amplifier according to claim 3, characterized in that: The space isolator (20) is provided with a heating ring on the outside.
5. A main amplifier according to claim 1, characterized in that: The beam-expanding lens group includes a first adjustable lens mount (30) and a second adjustable lens mount (40). A plano-concave lens (31) is mounted on the first adjustable lens mount (30), and a plano-convex lens (41) is mounted on the second adjustable lens mount (40).
6. A main amplifier according to claim 1, characterized in that: The reflector assembly includes a third adjustable mirror mount (50) and a fourth adjustable mirror mount (70). A first reflector (51) is mounted on the third adjustable mirror mount (50), and a second reflector (71) is mounted on the fourth adjustable mirror mount (70). The window plate (90) is located in the reflection direction of the second reflector (71), and the power meter (80) is located in the transmission direction of the second reflector (71).
7. A high-peak-value dual-pulse fiber laser, characterized in that: It includes a seed source (001), a 1*2 isolator (002), a 2*1 isolator (005), a first-stage amplification module, a second-stage amplification module, and a main amplifier (015) as described in any one of claims 1-6, which are connected in sequence by optical paths. The two outputs of the 1*2 isolator (002) are respectively connected to a delay fiber (003) and an acousto-optic modulator (004); The two input terminals of the 2*1 isolator (005) are respectively connected to the optical paths of the delay fiber (003) and the acousto-optic modulator (004), and its output terminal is connected to the optical path of the first-stage amplification module. The first-stage amplification module includes a third active optical fiber (006), a 980nm single-mode pump source (007), and a first wavelength division multiplexer (008) connected in sequence by optical paths, and a first online isolator (009) is provided between the first-stage amplification module and the second-stage amplification module. The secondary amplification module includes a second active optical fiber (010), a 915nm multimode pump source (011), and a pump signal combiner (012) connected in sequence by optical paths. A second in-line isolator (013) and a mode field adapter (014) are provided between the secondary amplification module and the main amplifier (015).