A continuous wave fiber laser
Patent Information
- Application Number
- CN202522270036.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-27
- Publication Date
- 2026-08-28
- Estimated Expiration
- 2035-10-27
AI Technical Summary
但是，同带泵浦技术方案系统复杂，成本高昂，难以批量生产以应用于材料加工等场景
[0023]1.激光器整体采用全光纤结构设计，所有光学元件均通过光纤熔接相连，有利于提高激光器的稳定性和可靠性集成度，降低了装配成本；
Smart Images
Figure CN224697206U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of laser technology, and in particular to a continuous fiber laser. Background Technology
[0002] Improving brightness and beam quality is an important research direction in the field of high-power continuous fiber laser technology. High-power, high-brightness lasers have irreplaceable advantages in some precision manufacturing applications due to their high power density: for example, when matched with scanning galvanometers, they can achieve high-speed and high-quality welding of copper materials for new energy batteries; when matched with short-focal-length cutting heads, they can complete processes such as high-precision small-hole cutting, greatly improving processing efficiency and finished product quality.
[0003] However, existing technologies still face key challenges in the field of high-power laser output. Conventional solutions increase output power by increasing pump power; however, when the output power exceeds 2kW, nonlinear effects cause the target output laser wavelength power to attenuate. In other words, the actual output power of the laser is limited by the nonlinear effects generated by the interaction between the laser and the fiber medium, making it impossible to achieve stable output of higher power lasers. Another approach is to increase the fiber core diameter and reduce the power density to suppress nonlinear effects, but this sacrifices beam quality and cannot overcome the 2kW power output bottleneck.
[0004] To overcome these limitations, the industry has proposed a band-pumping technology: first, a 915nm / 976nm semiconductor laser is converted into a 1018nm wavelength laser, and then the 1018nm wavelength laser is used as a high-brightness pump source to further amplify the output to 1080nm laser, thereby achieving high-power, high-brightness laser output. However, the band-pumping technology is complex, costly, and difficult to mass-produce for applications such as materials processing.
[0005] Therefore, how to effectively suppress the nonlinear effects of high-power single-mode laser output while significantly improving beam quality under the premise of low cost and simplified structure has become a key problem that urgently needs to be solved in the development of current high-power continuous fiber laser technology. Utility Model Content
[0006] This utility model provides a continuous fiber laser. The continuous fiber laser converts the received reverse pump light into signal light through a few-mode laser oscillator and transmits the signal light to a mode filter. The mode filter can filter out higher-order modes other than the fundamental mode in the signal light, realizing single-mode laser output. By setting the first cladding light filter at the output end of the continuous fiber laser, it can be ensured that the signal light output by the continuous fiber laser includes only the fundamental mode, thereby obtaining signal light with higher energy density, which is beneficial to laser processing.
[0007] This utility model provides a continuous fiber laser, comprising a few-mode laser oscillation cavity, a pump source, a mode filter, and a first cladding optical filter connected sequentially by optical fibers, wherein...
[0008] The pump source injects pump light into the few-mode laser oscillator cavity through a reverse pump combiner.
[0009] The few-mode laser oscillator is used to convert the received pump light into signal light and output the signal light to the mode filter. The few-mode laser oscillator supports multiple different modes of laser oscillation.
[0010] The mode filter is used to filter higher-order modes in the signal light into the fiber cladding, while the fiber core allows only a single fundamental mode laser to pass through.
[0011] The first cladding optical filter is used to strip away the higher-order mode light and residual pump light that have been filtered out by the mode filter and coupled into the fiber cladding.
[0012] Optionally, a second cladding optical filter is also included, disposed between the few-mode laser oscillator and the mode filter, for filtering out the light beam in the fiber cladding.
[0013] Optionally, the few-mode laser oscillation cavity includes a few-mode gain fiber, a first fiber grating, and a second fiber grating;
[0014] The first fiber grating and the second fiber grating are located at the two ends of the few-mode gain fiber, respectively, and the reflectivity of the first fiber grating is greater than that of the second fiber grating.
[0015] Optionally, the core diameter of the few-mode gain fiber is greater than or equal to 14 μm and less than or equal to 25 μm.
[0016] Optionally, the output end of the reverse pump combiner is coupled to the second fiber grating, and the pump light is coupled from the second fiber grating into the few-mode laser oscillator cavity for reverse pumping.
[0017] Optionally, the few-mode gain fiber has at least one local bend.
[0018] Optionally, the mode filter includes a first optical fiber, a tapered structure, and a second optical fiber connected in sequence. The core diameter of the input end of the tapered structure is the same as the core diameter of the first optical fiber, and the core diameter of the output end of the tapered structure is the same as the core diameter of the second optical fiber. The core diameter of the first optical fiber is larger than the core diameter of the second optical fiber.
[0019] Optionally, the core diameter of the conical structure decreases linearly or non-linearly along the output direction of the signal light.
[0020] Optionally, it also includes a laser output head, the input end of which is coupled to the output end of the first cladding optical filter, and the laser output head is used to output the signal light.
[0021] Optionally, the continuous fiber laser further includes an indicator light source connected to the second fiber grating for outputting indicator light, which is used to indicate the position of the spot of the signal light.
[0022] The continuous fiber laser provided by this embodiment of the invention will have the following beneficial effects:
[0023] 1. The laser adopts an all-fiber structure design, and all optical components are connected by fiber optic fusion splicing, which helps to improve the stability and reliability of the laser and reduce assembly costs;
[0024] 2. By adopting a reverse-pumping injection method, the pump light and signal light are transmitted in opposite directions within the gain fiber, which helps to reduce the output power of Raman light and suppress nonlinear effects;
[0025] 3. By using few-mode gain fiber as the laser oscillation medium and combining it with a downstream mode filter to perform mode selection on the beam output from the oscillation cavity, it is possible to obtain high output power while ensuring better single-mode beam quality.
[0026] 4. By introducing a local bend with a specific bending radius into the few-mode gain fiber, the bending loss principle can be used to effectively suppress higher-order mode oscillations and improve the purity of the fundamental mode, which is beneficial to achieving better laser processing results.
[0027] 5. The single-mode output power of the continuous fiber laser of this application can reach 3kW.
[0028] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this utility model, nor is it intended to limit the scope of this utility model. Other features of this utility model will become readily apparent from the following description. Attached Figure Description
[0029] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0030] Figure 1This is a schematic diagram of the structure of a continuous fiber laser provided in an embodiment of the present invention;
[0031] Figure 2 This is a schematic diagram of another continuous fiber laser provided in this embodiment of the present invention;
[0032] Figure 3 This is a schematic diagram of another continuous fiber laser provided in this embodiment of the present invention;
[0033] Figure 4 This is a schematic diagram of the coiled shape of a few-mode gain optical fiber provided in an embodiment of this utility model;
[0034] Figure 5 This is a schematic diagram of another coiled shape of a few-mode gain optical fiber provided in this embodiment of the present invention;
[0035] Figure 6 This is a schematic diagram of the structure of the pattern filter provided in an embodiment of the present invention;
[0036] Figure 7 This is a schematic diagram of another continuous fiber laser provided in this embodiment of the present invention.
[0037] Explanation of reference numerals in the attached figures:
[0038] 100, Pump source; 101, Pump light output unit; 102, Reverse pump combiner; 200, Few-mode laser oscillator cavity; 201, First fiber grating; 202, Second fiber grating; 203, Few-mode gain fiber; 300, Mode filter; 301, First fiber; 302, Tapered structure; 303, Third fiber; 304, First fiber core; 305, First fiber cladding; 306, Second fiber cladding; 307, Second fiber core; 400, Fiber; 500, First cladding optical filter; 501, Second cladding optical filter; 600, Laser output head; 700, Indicator light source. Detailed Implementation
[0039] To enable those skilled in the art to better understand this solution, the technical solutions in the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this utility model.
[0040] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the utility model described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0041] This utility model provides a continuous fiber laser. Figure 1 This is a schematic diagram of a continuous fiber laser provided in an embodiment of the present invention, for reference. Figure 1 Continuous fiber lasers consist of 400 ( Figure 1 The components (all connecting lines are optical fibers) are sequentially connected to a few-mode laser oscillator 200, a pump source 100, a mode filter 300, and a first cladding optical filter 500. The pump source 100 injects pump light into the few-mode laser oscillator 200 through a reverse pump combiner 102. The few-mode laser oscillator 200 converts the received pump light into signal light and outputs the signal light to the mode filter 300. The few-mode laser oscillator 200 supports multiple different modes of laser oscillation. The mode filter 300 filters out higher-order modes in the signal light and directs them into the fiber cladding, while only a single fundamental mode signal light passes through the fiber core. The first cladding optical filter 500 strips away the higher-order mode light filtered out by the mode filter 300 and coupled into the fiber cladding, as well as any residual pump light.
[0042] refer to Figure 1 Pump source 100 outputs pump light, and few-mode laser oscillator 200 absorbs the pump light and radiates signal light. The signal light oscillates in the few-mode laser oscillator 200. Signal light modes that satisfy the resonance condition of the few-mode laser oscillator 200 are amplified in the few-mode laser oscillator 200, while signal light modes that do not satisfy the resonance condition of the few-mode laser oscillator 200 are lost in the few-mode laser oscillator 200. In specific implementations, pump source 100 may include multiple pump light output units 101 ( Figure 1 (Only two pump light output units 101 are shown schematically, and this is not a limitation of the present invention.) The pump light output by the multiple pump light output units 101 is coupled into the few-mode laser oscillation cavity 200 after being combined by the reverse pump combiner 102.
[0043] In one embodiment, the reverse pump combiner 102 can be of type (6+1)×1 or type (12+1)×1, and the core of the output fiber of the reverse pump combiner 102 can be 20μm. The output power of a single pump light output unit 101 can be 600W to 1000W, and the total output power of multiple pump light output units 101 can reach 4000W to 5000W.
[0044] In this application, the few-mode laser oscillator 200 includes two cavity mirrors respectively disposed at both ends, one cavity mirror having a higher reflectivity and the other cavity mirror having a lower reflectivity. The signal light mode satisfying the resonance condition of the few-mode laser oscillator 200 is amplified multiple times within the cavity by the high-reflectivity and low-reflectivity cavity mirrors before being output to the mode filter 300. The mode filter 300 transmits higher-order modes in the signal light to the fiber cladding and the fundamental mode to the fiber core. Then, the higher-order modes and residual pump light are filtered out by the first cladding optical filter 500, achieving single-mode laser output.
[0045] The continuous fiber laser provided by this utility model embodiment has the following beneficial effects: the laser adopts an all-fiber structure design, and all optical components are connected by fiber fusion splicing, which is conducive to improving the stability and reliability of the laser and reducing assembly costs; by adopting a reverse pumping injection method, the pump light and signal light are transmitted in opposite directions within the gain fiber, which helps to reduce the output power of Raman light and suppress nonlinear effects; by using the few-mode gain fiber as the laser oscillation medium, and cooperating with the downstream mode filter to perform mode selection on the beam output from the oscillation cavity, it is possible to obtain high output power while ensuring good single-mode beam quality; by introducing a local bending section with a specific bending radius on the few-mode gain fiber, the bending loss principle is used to effectively suppress higher-order mode oscillation and improve the purity of the fundamental mode, which is conducive to achieving better laser processing results. The single-mode output power of the continuous fiber laser of this application can reach 3kW.
[0046] Figure 2 This is a schematic diagram of another continuous fiber laser provided in this embodiment of the present invention, for reference. Figure 2 Optionally, the continuous fiber laser also includes a second cladding optical filter 501, which is disposed between the few-mode laser oscillation cavity 200 and the mode filter 300 to filter out the beam in the fiber cladding.
[0047] By setting a second cladding optical filter 501, the residual pump light and spontaneous emission light mixed in the fiber cladding of the signal light output from the few-mode laser oscillator cavity 200 can be stripped in advance before the signal light enters the mode filter 300, thus preventing such stray light from entering the mode filter 300 along with the signal light.
[0048] Continue to refer to Figure 2 Optionally, the continuous fiber laser also includes a laser output head 600, the input end of which is coupled to the output end of the first cladding optical filter 500, and the laser output head 600 is used to output signal light.
[0049] The laser output head 600 may include structures such as a collimating lens. Setting up the laser output head 600 can improve the beam quality of the output laser to meet the needs of different scenarios.
[0050] Figure 3 This is a schematic diagram of another continuous fiber laser provided in this embodiment of the present invention, for reference. Figure 3 The few-mode laser oscillation cavity 200 includes a few-mode gain fiber 203, a first fiber grating 201, and a second fiber grating 202. The first fiber grating 201 and the second fiber grating 202 are located at the two ends of the few-mode gain fiber 203, respectively. The reflectivity of the first fiber grating 201 is much greater than that of the second fiber grating 202.
[0051] refer to Figure 3 The first fiber grating 201 and the second fiber grating 202 act as cavity mirrors of the few-mode laser oscillator 200, reflecting the signal light so that it oscillates within the cavity. Signal light modes satisfying the resonance condition of the few-mode laser oscillator 200 are amplified, while those not satisfying are lost. The first fiber grating 201 exhibits high reflectivity, while the second fiber grating 202 partially reflects and partially transmits the incident signal light. The transmitted signal light from the second fiber grating 202 serves as the output light of the oscillator, transmitted to the downstream mode filter 300. The second fiber grating 202 is essentially the output end of the few-mode laser oscillator 200.
[0052] Furthermore, since continuous fiber lasers ultimately aim to achieve single-mode laser output, the few-mode gain fiber 203 should be made of fiber with a smaller core diameter to suppress higher-order modes. In specific implementation, the core diameter of the few-mode gain fiber 203 can be designed to be greater than 14μm and less than or equal to 25μm.
[0053] Specifically, if the core diameter is less than 14μm, only single-mode transmission can be achieved. The excessively small core space will lead to excessively high optical power density. When the output power is increased to 3kW, nonlinear effects such as stimulated Raman scattering and stimulated Brillouin scattering are easily induced. At the same time, the absorption efficiency of the core for pump light is greatly reduced, making it difficult to achieve high power output. If the core diameter is greater than 25μm, although the power density can be reduced to alleviate nonlinear effects, it will support more higher-order modes to oscillate simultaneously. These modes compete fiercely in the cavity, resulting in poor output power stability. Even after processing by mode filter 300, it is difficult to completely filter out all higher-order modes, and the beam quality is significantly reduced.
[0054] Continue to refer to Figure 3 The output end of the pump source 100 is coupled to the second fiber grating 202, and the pump light is coupled from the second fiber grating 202 into the few-mode laser oscillator 200 for reverse pumping. Alternatively, the pump light can be coupled from one end of the output signal light of the few-mode laser oscillator 200 into the few-mode laser oscillator 200, i.e., from the second fiber grating 202 with lower transmittance into the few-mode laser oscillator 200. This pumping method is called reverse pumping. Reverse pumping can suppress Raman nonlinear effects, thereby reducing the intensity of Raman light in the signal light, and consequently reducing the intensity of Raman light in the return light. Optionally, the wavelength of the pump light can be in the range of 975nm to 977nm. The few-mode gain fiber 203 has a high absorption coefficient for pump light in this wavelength range, thus the length of the few-mode gain fiber 203 can be shortened accordingly, thereby suppressing Raman nonlinear effects. Furthermore, a 976nm wavelength laser can be used as the pump light.
[0055] In embodiments of this application, at least one local bend is provided on the few-mode gain fiber. Optionally, the coiling shape of the few-mode gain fiber includes racetrack shape, figure-eight shape, B shape, wave shape, zigzag shape, and a combination arc shape formed by smoothly splicing arcs with different radii of curvature.
[0056] By setting part or all of the few-mode gain fiber into a bent structure, the loss of higher-order modes in the bent structure can be increased, thereby suppressing higher-order modes and concentrating the signal light mode on the fundamental mode.
[0057] Optionally, the curvature radius of the local bend is greater than or equal to 4 cm and less than or equal to 8 cm. Within this range, the curvature radius can effectively suppress higher-order modes.
[0058] Figure 4 This is a schematic diagram of the coiled shape of a few-mode gain optical fiber provided in an embodiment of this utility model. Figure 5 This is a schematic diagram of another coiled shape of a few-mode gain optical fiber provided in an embodiment of this utility model, for reference. Figure 4 and Figure 5The coiling shape of few-mode gain fiber includes racetrack-shaped or figure-eight-shaped. Both racetrack-shaped and figure-eight-shaped fibers have a curved structure, and coiling the few-mode gain fiber in this shape can suppress higher-order modes.
[0059] Figure 6 This is a schematic diagram of the structure of the pattern filter provided in an embodiment of this utility model, for reference. Figure 6 The mode filter includes a first optical fiber 301, a tapered structure 302, and a second optical fiber 303 connected in sequence. The first optical fiber 301 is connected to the input end of the tapered structure 302, and the second optical fiber 303 is connected to the output end of the tapered structure 302. The first optical fiber 301 is used to couple the signal light into the tapered structure 302. The tapered structure 302 is used to increase the loss of higher-order modes of the signal light, filter out higher-order modes, and output the fundamental mode to the second optical fiber 303. The core diameter of the input end of the tapered structure 302 is the same as the core diameter of the first optical fiber 302, and the core diameter of the output end of the tapered structure 302 is the same as the core diameter of the second optical fiber 303. The core diameter of the first optical fiber 301 is larger than the core diameter of the second optical fiber 303.
[0060] In one embodiment, the core diameter of the cone-shaped structure 302 decreases linearly or non-linearly along the output direction of the signal light.
[0061] It is understandable that when the core diameter of the conical structure 302 decreases linearly along the output direction of the signal light, the effective refractive index for higher-order modes gradually decreases as the core diameter decreases. Higher-order modes will leak uniformly into the cladding along the conical structure 302, while the fundamental mode remains in the core and is stably transmitted to the second fiber 303, ultimately achieving a better filtering effect, and the consistency of the linear gradient process is also better.
[0062] In some other embodiments, the core diameter of the cone structure 302 decreases nonlinearly along the output direction of the signal light.
[0063] Continue to refer to Figure 1 and Figure 6 For example, the first optical fiber 301 is a few-mode fiber, which can transmit fewer modes than a multimode fiber. A few-mode fiber typically transmits 2 to 6 modes (transverse modes), fewer than a multimode fiber. The second optical fiber 303 is a single-mode fiber, with a core diameter larger than that of a single-mode fiber. Since the cladding has a relatively small impact on the signal light in the core, there can be a certain difference between the cladding diameter at the input end of the tapered structure 302 and the diameter of the cladding 305 of the first optical fiber 301. The input end of the mode filter 300 is coupled to one end of the output signal light of the few-mode laser oscillator 200. The gain fiber in the few-mode laser oscillator 200 is a few-mode gain fiber, and the signal light in the few-mode gain fiber includes at least two modes.
[0064] In one embodiment, the cladding diameter of the few-mode gain fiber is 400 μm, and the core diameter is 20 μm. The core diameter 304 of the first fiber 301 needs to be the same as the core diameter of the few-mode gain fiber, while the cladding diameter 305 of the first fiber 301 can differ to some extent from the cladding diameter of the few-mode gain fiber. The output end of the mode filter 300 is coupled to a single-mode fiber, which has a cladding diameter of 250 μm and a core diameter of 14 μm. The core diameter 307 of the second fiber 303 needs to be the same as the core diameter of the single-mode fiber, while the cladding diameter 306 of the second fiber 303 can differ to some extent from the cladding diameter of the few-mode gain fiber. After entering the conical structure 302, the higher-order modes leak into the cladding 306 of the second fiber 303, while the fundamental mode enters the conical structure 302 and couples into the core 307 of the second fiber 303. Thus, the mode filter 300 can increase the loss of the higher-order modes, enabling the continuous fiber laser to achieve single-mode laser output.
[0065] Figure 7 This is a schematic diagram of another continuous fiber laser provided in this embodiment of the present invention, for reference. Figure 7 The continuous fiber laser also includes an indicator light source 700, which outputs an indicator light whose optical path coincides with that of the signal light. The indicator light is used to indicate the position of the signal light spot. Since the signal light may not be in the visible light band, such as the infrared band, the indicator light source 700 can emit an indicator light in the visible light band. The indicator light can indicate the optical path of the signal light and the position of the signal light spot, thus making the optical path of the continuous fiber laser more obvious and facilitating the debugging of the continuous fiber laser.
[0066] Compared with the prior art, the continuous fiber laser provided by this utility model embodiment will have the following beneficial effects:
[0067] 1. The laser adopts an all-fiber structure design, and all optical components are connected by fiber optic fusion splicing, which helps to improve the stability and reliability of the laser and reduce assembly costs;
[0068] 2. By adopting a reverse-pumping injection method, the pump light and signal light are transmitted in opposite directions within the gain fiber, which helps to reduce the output power of Raman light and suppress nonlinear effects;
[0069] 3. By using few-mode gain fiber as the laser oscillation medium and combining it with a downstream mode filter to perform mode selection on the beam output from the oscillation cavity, it is possible to obtain high output power while ensuring better single-mode beam quality.
[0070] 4. By introducing a local bend with a specific bending radius into the few-mode gain fiber, the bending loss principle can be used to effectively suppress higher-order mode oscillations and improve the purity of the fundamental mode, which is beneficial to achieving better laser processing results.
[0071] 5. The single-mode output power of the continuous fiber laser of this application can reach 3kW.
[0072] The specific embodiments described above do not constitute a limitation on the scope of protection of this utility model. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.
Claims
1. A continuous fiber laser, characterized in that, It includes a few-mode laser oscillator cavity, a pump source, a mode filter, and a first cladding optical filter, which are connected in sequence by optical fibers. The pump source injects pump light into the few-mode laser oscillator cavity through a reverse pump combiner. The few-mode laser oscillator is used to convert the received pump light into signal light and output the signal light to the mode filter. The few-mode laser oscillator supports multiple different modes of laser oscillation. The mode filter is used to filter higher-order modes in the signal light into the fiber cladding, while the fiber core allows only a single fundamental mode signal light to pass through. The first cladding optical filter is used to strip away the higher-order mode light and residual pump light that have been filtered out by the mode filter and coupled into the fiber cladding.
2. The continuous fiber laser according to claim 1, characterized in that, It also includes a second cladding optical filter, which is disposed between the few-mode laser oscillator and the mode filter to filter out the light beam in the fiber cladding.
3. The continuous fiber laser according to claim 1, characterized in that, The few-mode laser oscillation cavity includes a few-mode gain fiber, a first fiber grating, and a second fiber grating; The first fiber grating and the second fiber grating are located at the two ends of the few-mode gain fiber, respectively, and the reflectivity of the first fiber grating is greater than that of the second fiber grating.
4. The continuous fiber laser according to claim 3, characterized in that, The core diameter of the few-mode gain fiber is greater than or equal to 14 μm and less than or equal to 25 μm.
5. The continuous fiber laser according to claim 3, characterized in that, The output end of the reverse pump combiner is coupled to the second fiber grating, and the pump light is coupled from the second fiber grating into the few-mode laser oscillator cavity for reverse pumping.
6. The continuous fiber laser according to claim 3, characterized in that, The few-mode gain fiber has at least one local bend.
7. The continuous fiber laser according to claim 1, characterized in that, The mode filter includes a first optical fiber, a tapered structure, and a second optical fiber connected in sequence. The core diameter of the input end of the tapered structure is the same as the core diameter of the first optical fiber, and the core diameter of the output end of the tapered structure is the same as the core diameter of the second optical fiber. The core diameter of the first optical fiber is larger than the core diameter of the second optical fiber.
8. The continuous fiber laser according to claim 7, characterized in that, The diameter of the fiber core of the cone-shaped structure decreases linearly or non-linearly along the output direction of the signal light.
9. The continuous fiber laser according to claim 1, characterized in that, It also includes a laser output head, the input end of which is coupled to the output end of the first cladding optical filter, and the laser output head is used to output the signal light.
10. The continuous fiber laser according to claim 3, characterized in that, The continuous fiber laser also includes an indicator light source connected to the second fiber grating for outputting indicator light, which is used to indicate the position of the spot of the signal light.