Fiber laser

Abstract

The embodiment of the utility model discloses an optical fiber laser, and relates to the field of optical fiber amplification technology application. The optical fiber laser is composed of a laser source, a light splitting assembly, an optical fiber amplification assembly, a beam combining assembly and a shaping lens, laser emitted by the laser source is split into multiple sub laser beams through the light splitting assembly, and the multiple sub laser beams are subjected to energy density amplification through the optical fiber amplification assembly; and the beam combining assembly combines the multiple sub laser beams after energy density amplification, so that the energy density of the laser is increased, and the defects that the energy density of the laser is reduced and the quality of the laser beams is reduced due to wavelength conversion are overcome.

Description

Technical Field

[0001] This application relates to the application of fiber optic amplification technology, specifically to fiber lasers. Background Technology

[0002] In traditional technologies, neither gas lasers, solid-state lasers, nor other types of lasers can achieve continuous wavelength selection, resulting in a very limited range of laser wavelengths that can be used on a large scale in industry. Therefore, lasers with wavelengths close to the application requirements can only be obtained through a series of conversion methods. However, this wavelength conversion process causes a significant loss of laser energy, leading to a substantial reduction in the beam quality and energy density of the converted laser. Utility Model Content

[0003] This application provides a fiber laser to improve the problem of a significant reduction in laser beam quality and energy density caused by wavelength conversion.

[0004] This application provides a fiber laser, including:

[0005] Laser source;

[0006] A beam splitting component is disposed at the laser emission end of the laser source and is used to split the laser emitted by the laser source into multiple sub-laser beams.

[0007] An optical fiber amplification component is disposed at the laser output end of the beam splitter and is used to amplify the energy density of the sub-laser beam;

[0008] A beam combiner is located at the laser output end of the fiber optic amplifier and is used to combine multiple sub-laser beams.

[0009] A shaping lens is disposed at the laser output end of the beam combining assembly.

[0010] In some embodiments of this application, the beam splitting component includes a multi-stage beam splitter, all of which are disposed at the laser emission end of the laser source and are used to split the laser beam into multiple sub-laser beams.

[0011] In some embodiments of this application, the beam splitter splits the laser beam into transmitted light and reflected light, the optical path of the transmitted light is perpendicular to the optical path of the reflected light, and multiple beam splitters are arranged at intervals along the path of the reflected light.

[0012] In some embodiments of this application, the beam splitting assembly further includes a reflector located on the path of the reflected light from the final beam splitter.

[0013] In some embodiments of this application, the fiber optic amplification assembly includes a multi-stage fiber optic amplification group. In the fiber optic amplification group before the final stage, the first-stage fiber optic amplification group is located on one side of the transmitted light of the first-stage beam splitter, and the final-stage fiber optic amplification group is located on the path of the reflected light of the reflector.

[0014] In some embodiments of this application, the fiber optic amplification group includes an optical fiber, a coupler, and an optical fiber amplifier. The coupler is connected to one end of the optical fiber and is located between the beam splitter and the optical fiber, and is used to couple the transmitted light into the optical fiber. The optical fiber amplifier is disposed on the optical fiber and is used to amplify the energy density of the sub-laser beam transmitted through the optical fiber.

[0015] In some embodiments of this application, the fiber optic amplifier group further includes a first combiner and a second combiner. The first combiner is disposed on the fiber optic line and located at the input end of the fiber optic amplifier, and the second combiner is disposed on the fiber optic line and located at the output end of the fiber optic amplifier.

[0016] In some embodiments of this application, the fiber amplification group further includes a first excitation source and a second excitation source, wherein the first excitation source is connected to the first combiner and the second excitation source is connected to the second combiner.

[0017] In some embodiments of this application, a first isolator and a second isolator are provided on the optical fiber line, the first isolator being located between the coupler and the first combiner, and the second isolator being located at the output end of the second combiner.

[0018] In some embodiments of this application, a condenser is provided on one side of the beam splitter along the direction of the transmitted light, and the condenser is located between the beam splitter and the coupler, for focusing the transmitted light into the coupler.

[0019] Therefore, the fiber laser disclosed in the embodiments of this application comprises a laser source, a beam splitter, a fiber amplification component, a beam combiner, and a shaping lens. The beam splitter divides the laser beam emitted from the laser source into multiple sub-beams. The fiber amplification component amplifies the energy density of these sub-beams. The beam combiner then combines these amplified beams, increasing the laser's energy density to compensate for the energy density reduction and beam quality degradation caused by wavelength changes. Specifically, the beam splitter decomposes the single laser beam from the laser source into multiple sub-beams, with the energy of each sub-beam evenly distributed to reduce the energy load on the fiber amplification component. Each sub-beam is amplified by the fiber amplification component, utilizing the interaction between the fiber doping medium (such as erbium-doped or ytterbium-doped) and the pump light to significantly increase the energy density of the sub-beams through stimulated emission. The amplified multiple laser beams are then combined by the beam combiner into a single high-energy-density beam while maintaining the beam's directionality and mode quality. Shaping lenses are used to adjust the shape and spot distribution of the beam after beam combining, ensuring the uniformity and collimation of the output beam to suit specific application scenarios. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of a fiber laser provided in an embodiment of this application;

[0022] Figure 2 This is a schematic diagram of another fiber laser provided in an embodiment of this application.

[0023] Explanation of reference numerals in the attached figures:

[0024] 1. Laser source; 2. Beam splitter assembly; 21. Beam splitter mirror; 22. Reflector mirror; 3. Fiber optic amplifier assembly; 31. Fiber optic cable; 32. Coupler; 33. Fiber optic amplifier; 34. First beam combiner; 35. Second beam combiner; 36. First excitation source; 37. Second excitation source; 38. First isolator; 39. Second isolator; 4. Beam combiner assembly; 5. Shaping lens; 6. Condenser mirror; 7. Beam expander mirror. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or specifying the number of technical features indicated. Therefore, features defined with "first" and "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0027] Please see Figures 1 to 2 The embodiments of this application provide a fiber laser, including a laser source 1, a beam splitter 2, a fiber amplification assembly 3, a beam combiner 4, and a shaping lens 5.

[0028] The beam splitter 2 is located at the laser emission end of the laser source 1 and is used to split the laser beam emitted by the laser source 1 into multiple sub-laser beams. The fiber optic amplifier 3 is located at the laser output end of the beam splitter 2 and is used to amplify the energy density of the sub-laser beams. The beam combiner 4 is located at the laser output end of the fiber optic amplifier 3 and is used to combine the multiple sub-laser beams. The shaping lens 5 is located at the laser output end of the beam combiner 4.

[0029] The technical solution provided in this application utilizes a beam splitter 2 to split the laser beam emitted from a laser source 1 into multiple sub-laser beams. An optical fiber amplification component 3 amplifies the energy density of these sub-laser beams, and a beam combiner 4 combines the amplified beams to increase the laser's energy density, thus compensating for the energy density reduction and beam quality degradation caused by wavelength changes. Specifically, the beam splitter 2 decomposes the single laser beam from the laser source 1 into multiple sub-laser beams, with the energy of each sub-beam evenly distributed to reduce the energy load on the optical fiber amplification component 3. Each sub-laser beam is amplified by the optical fiber amplification component 3, and the interaction between the fiber doping medium (such as erbium-doped or ytterbium-doped) and the pump light significantly increases the energy density of the sub-beams through stimulated emission. The amplified multiple laser beams are then combined into a single high-energy-density beam by the beam combiner 4, while maintaining the beam's directionality and mode quality. A shaping lens 5 is used to adjust the shape and spot distribution of the combined beam, ensuring the uniformity and collimation of the output beam to suit specific application scenarios.

[0030] In some embodiments, the beam splitter 2 includes a multi-stage beam splitter 21, each stage located at the laser emission end of the laser source 1, for splitting the laser beam into multiple sub-beams. In this embodiment, the beam splitter 2 employs a two-stage beam splitter 21 structure, including a first-stage beam splitter 21 and a second-stage beam splitter 21. The first-stage beam splitter 21 is composed of a semi-transparent reflective film, used to split the laser beam emitted from the laser source 1 into transmitted light and reflected light. The transmitted light continues to propagate along the original optical path, while the reflected light is deflected by 90°. The second-stage beam splitter 21 is located on the path of the reflected light from the first-stage beam splitter 21, for further beam splitting, further splitting the reflected light into transmitted light and reflected light.

[0031] The semi-transparent reflective film of beam splitter 21 is designed with specific transmittance and reflectance. For example, the first-stage beam splitter 21 has a transmittance of 25% and a reflectance of 75%, which splits the laser beam energy into two beams. The second-stage beam splitter 21 still has a reflectance of 66.7%, further splitting the first-stage reflected light into two beams, and so on. Finally, the entire beam splitter assembly 2 outputs four sub-laser beams of equal energy. In this embodiment, beam splitter 21 is made of a quartz glass substrate with a specific beam splitting film (dielectric film) coated on its surface. The first-stage beam splitter 21 has a transmittance of 25% and a reflectance of 75%, used for initial beam splitting. The second-stage beam splitter 21 has a transmittance of 33.3% and a reflectance of 66.7%, further splitting the reflected light beams.

[0032] Directly inputting high-energy laser light into a traditional fiber laser can cause the fiber amplifier 33 to exceed its damage threshold, affecting system stability. By splitting a single high-energy laser beam into multiple low-energy beams, the input optical power of each amplifier can be reduced, thereby improving system reliability. Furthermore, the multi-stage beam splitter 21 can precisely control the beam splitting ratio at each stage, ensuring energy balance among the sub-beams.

[0033] Furthermore, beam splitter 21 splits the laser beam into transmitted and reflected rays. The optical paths of the transmitted and reflected rays are perpendicular. Multiple beam splitters 21 are sequentially spaced along the path of the reflected rays, ensuring that the reflected rays are split step-by-step, ultimately separating multiple laser beams. The first-stage beam splitter 21 splits the laser beam into a transmitted ray and a reflected ray. The transmitted ray propagates in a straight line, while the reflected ray is deflected by 90°. The second-stage beam splitter 21 is positioned on the path of the reflected ray from the first-stage beam splitter 21, again splitting the reflected ray into transmitted and reflected rays. The multiple-stage beam splitters 21 are arranged sequentially to ensure a progressively balanced distribution of the beam splitting ratio. By adjusting the incident angle of the beam splitter 21, the laser beam is precisely incident on the center of the beam splitting film, avoiding uneven light energy distribution. The perpendicular optical path design of the multiple-stage beam splitters 21 completely separates the directions of the transmitted and reflected rays, preventing interference between beams. By adopting a design where transmitted and reflected light are perpendicular, the space in the vertical direction can be used to the maximum extent to arrange multiple beam splitters 21, making the system more compact.

[0034] In some embodiments, see Figure 2 The beam splitter assembly 2 also includes a reflector 22, which is located on the path of the reflected light from the final beam splitter 21. The reflector 22 is a plane mirror using high-reflectivity coating technology, achieving a reflectivity of over 99% to ensure efficient reflection of laser energy. Positioned on the path of the reflected light from the final beam splitter 21, the reflector 22 adjusts the reflected light from the final beam splitter 21 to a new optical path direction. This new optical path direction is the same as the direction of the transmitted light, preventing some light from the final beam splitter 21 from being unable to enter the fiber amplification assembly 3 due to reflection, thus avoiding energy loss. After reflection by the reflector 22, the laser beam reflected by the final beam splitter 21 remains parallel to the transmitted light from the preceding beam splitter 21, both pointing towards the input end of the same fiber amplification assembly 3. The reflector 22 only adjusts the reflected light from the final beam splitter 21; the transmitted and reflected light from other beam splitters 21 are unaffected. The reflector 22 adjusts the reflected light from the final beam splitter 21 to be parallel to the transmitted light, so that all beams can enter the fiber amplifier 33 or the beam combiner in a consistent manner, thereby improving the efficiency and stability of optical path integration.

[0035] In some embodiments, the fiber optic amplification assembly 3 includes a multi-stage fiber optic amplification group. In the fiber optic amplification group before the final stage, the first-stage fiber optic amplification group is located on one side of the transmitted light from the first-stage beam splitter 21, and the final-stage fiber optic amplification group is located on the path of the reflected light from the reflector 22. By establishing a one-to-one correspondence between the fiber optic amplification groups and beam splitters 21 in the fiber optic amplification group before the final stage, the sub-laser beams split by each stage beam splitter 21 can enter the corresponding fiber optic amplification group for energy density enhancement. The reflected light from the final-stage beam splitter 21, after being oriented by the reflector 22, is coupled to the input end of the final-stage fiber optic amplification group. The final-stage fiber optic amplification group is responsible for the final amplification of the reflected light, preventing the light reflected from the last stage beam splitter 21 from failing to enter the fiber optic amplification group and causing some energy loss.

[0036] Further, please see Figure 2 The fiber optic amplification assembly includes an optical fiber 31, a coupler 32, and an optical fiber amplifier 33. The coupler 32 is connected to one end of the optical fiber 31 and located between the beam splitter 21 and the optical fiber 31, used to couple transmitted light to the optical fiber 31. The optical fiber amplifier 33 is located on the optical fiber 31 and used to amplify the energy density of the sub-laser beam transmitted through the optical fiber 31. The optical fiber 31 is used to transmit the laser and is selected from single-mode or multimode doped fibers adapted to the target wavelength. For example, erbium-doped fiber (EDFA) is used for lasers with a wavelength of 1064 nm. The coupler 32 is located at the input end of the optical fiber 31 and is used to precisely couple the transmitted light output from the beam splitter 2 or the reflected light adjusted by the mirror 22 into the optical fiber 31. The optical fiber amplifier 33 is positioned along the optical fiber 31 and provides gain through an external pump source, amplifying the laser power passing through the optical fiber 31. The coupler 32 uses a free-space coupling method, precisely guiding the split laser light to the input end of the optical fiber 31 through a collimating lens, achieving a coupling efficiency of over 95% and minimizing coupling loss. The fiber amplifier 33 consists of a doped fiber and an external pump source. The length of the fiber and the pump power are optimized according to the target gain requirements. The pump source is typically a semiconductor laser with a wavelength matched to the absorption peak of the fiber doped ions; for example, a 980nm pump light is used to excite an erbium-doped fiber. The fiber amplifier 33 can amplify the input laser power by tens of times or more, while maintaining high beam quality. The transmitted light output from the beam splitter 21 is directly coupled to fiber 31, and the reflected light is oriented by the reflector 22 and then coupled to another fiber 31. Each fiber 31 is connected to an independent fiber amplifier 33 for amplification. The amplified beam is then output to the beam combiner 4 or other optical systems to complete energy aggregation or application processing.

[0037] In some embodiments, a beam expander 7 is provided at the laser emission end of the laser source 1, and the beam expander 7 is located between the beam splitter 2 and the laser source 1. That is, before the laser beam is split, the beam is expanded to increase the diameter of the laser beam, reduce the beam divergence angle, and improve the beam collimation.

[0038] In some embodiments, see Figure 2 The fiber optic amplifier group also includes a first combiner 34 and a second combiner 35. The first combiner 34 is located on the fiber optic cable 31 at the input end of the fiber optic amplifier 33, and the second combiner 35 is located on the fiber optic cable 31 at the output end of the fiber optic amplifier 33. The first combiner 34, located at the input end of the fiber optic amplifier 33, guides and couples the multi-beam split laser beam into a single fiber, avoiding energy dispersion and loss at the input stage. The first combiner 34 employs a fiber-coupled design, introducing multiple beams of light in spatial or fiber form through multiple input ports and converting them into a single fiber output. The combining efficiency exceeds 95%, with minimal loss. The second combiner 35, located at the output end of the fiber optic amplifier 33, combines the amplified laser beams into a single high-power laser beam.

[0039] In some embodiments, the fiber amplifier group further includes a first excitation source 36 and a second excitation source 37. The first excitation source 36 is connected to a first combiner 34 and provides pump light to the input of the fiber amplifier 33 via optical coupling. The first excitation source 36 is a semiconductor laser with a wavelength matching the absorption peak of the fiber doped ions, and a power of 10W to 50W. The excitation light is connected to the first combiner 34 via a fiber coupling module to achieve efficient pumping. The second excitation source 37 is connected to a second combiner 35 and is used to provide compensating pump light for the beam after multi-stage amplification, ensuring that the final output beam power reaches the target value.

[0040] In some embodiments, the optical fiber 31 is provided with a first isolator 38 and a second isolator 39. The first isolator 38 is located between the coupler 32 and the first beam combiner 34, and is used to prevent backscattered light during the coupling process from entering the fiber amplifier 33. When the coupler 32 introduces a laser beam into the optical fiber 31, some light may be reflected due to reflection at the fiber input end face, forming backscattered light. The first isolator 38, through a unidirectional light transmission design, blocks the reflected light from returning to the coupler 32. The first isolator 38 adopts a design combining a Faraday rotator and a polarization beam splitter. When the beam enters the isolator, it undergoes a 45° polarization rotation via the Faraday rotator; when the backscattered light passes through the isolator again, its polarization direction is further rotated, deviating from the original incident light path, thereby achieving unidirectional light transmission.

[0041] The second isolator 39 is located at the output end of the second combiner 35 and is used to prevent the back-reflected light of the final output beam from entering the fiber amplifier 33 and the second combiner 35. The second isolator 39 isolates reflected light that the output laser may encounter (e.g., back-reflected light from processing highly reflective materials), preventing reflected light from entering the fiber amplification link and affecting amplification efficiency or causing device damage. The second isolator 39 employs Faraday rotation polarization isolation technology and integrates a high-reflectivity, damage-resistant coating to adapt to high-power laser reflection environments.

[0042] In some embodiments, see Figure 2 A condenser lens 6 is provided on one side of the beam splitter 21 along the direction of the transmitted light. The condenser lens 6 is located between the beam splitter 21 and the coupler 32, and is used to focus the transmitted light into the coupler 32. The condenser lens 6 is a convex lens or a compound lens, with an anti-reflective coating on its surface to reduce energy loss during beam passage. The focal length and aperture of the condenser lens 6 are designed according to the beam diameter of the laser beam and the input characteristics of the coupler 32, ensuring that the beam is focused within the effective input area of ​​the coupler 32. The condenser lens 6 is located on the propagation path of the transmitted light from the beam splitter 21, close to the input end of the coupler 32, and can moderately constrict and collimate the beam. By moderately focusing, the condenser lens 6 adjusts the divergence angle and spot diameter of the laser beam, giving the beam higher light energy density and directionality before entering the coupler 32. The condenser lens 6 also acts as a collimator, converging potentially slightly divergent transmitted light into a collimated beam, facilitating stable beam entry into the fiber optic amplification assembly. The focal point of the condenser lens 6 is aligned with the input port of the coupler 32, resulting in a stable optical path and minimal light energy loss.

[0043] The basic concepts have been described above. Obviously, for those skilled in the art, the detailed disclosure above is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore remain within the spirit and scope of the exemplary embodiments of this application.

[0044] Furthermore, this application uses specific terms to describe embodiments of the application. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of the application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0045] Similarly, it should be noted that, in order to simplify the description of the present application and thus aid in the understanding of one or more embodiments, the foregoing description of the embodiments of the present application sometimes combines multiple features into a single embodiment, drawing, or description thereof. However, this disclosure method does not imply that the subject matter of the present application requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of the single embodiments disclosed above.

[0046] For each patent, patent application, patent application publication, and other material such as articles, books, specifications, publications, and documents referenced in this application, the entire contents of that patent application are incorporated herein by reference, except for historical application documents that are inconsistent with or conflict with the content of this application, and documents that limit the broadest scope of the claims of this application (currently or subsequently appended to this application). It should be noted that if there are any inconsistencies or conflicts between the descriptions, definitions, and / or terminology used in the supplementary materials of this application and the content of this application, the descriptions, definitions, and / or terminology used in this application shall prevail.

[0047] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A fiber laser, characterized in that, include: Laser source; A beam splitting component is disposed at the laser emission end of the laser source and is used to split the laser emitted by the laser source into multiple sub-laser beams. An optical fiber amplification component is disposed at the laser output end of the beam splitter and is used to amplify the energy density of the sub-laser beam; A beam combiner is located at the laser output end of the fiber optic amplifier and is used to combine multiple sub-laser beams. A shaping lens is disposed at the laser output end of the beam combining assembly.

2. The fiber laser according to claim 1, characterized in that, The beam splitting assembly includes multiple beam splitters, each of which is located at the laser emission end of the laser source and is used to split the laser beam into multiple sub-laser beams.

3. The fiber laser according to claim 2, characterized in that, The beam splitter splits the laser beam into transmitted light and reflected light, with the optical path of the transmitted light perpendicular to the optical path of the reflected light. Multiple beam splitters are arranged at intervals along the path of the reflected light.

4. The fiber laser according to claim 3, characterized in that, The beam splitter also includes a reflector located on the path of the reflected light from the final beam splitter.

5. The fiber laser according to claim 4, characterized in that, The fiber optic amplification assembly includes multiple fiber optic amplification groups. In the fiber optic amplification groups before the final stage, the first-stage fiber optic amplification group is located on one side of the transmitted light from the first-stage beam splitter, and the final-stage fiber optic amplification group is located on the path of the reflected light from the reflector.

6. The fiber laser according to claim 5, characterized in that, The fiber optic amplifier group includes an optical fiber, a coupler, and an optical fiber amplifier. The coupler is connected to one end of the optical fiber and is located between the beam splitter and the optical fiber, and is used to couple the transmitted light into the optical fiber. The optical fiber amplifier is disposed on the optical fiber and is used to amplify the energy density of the sub-laser beam transmitted through the optical fiber.

7. The fiber laser according to claim 6, characterized in that, The fiber amplifier group further includes a first combiner and a second combiner. The first combiner is disposed on the fiber and located at the input end of the fiber amplifier, and the second combiner is disposed on the fiber and located at the output end of the fiber amplifier.

8. The fiber laser according to claim 7, characterized in that, The fiber optic amplifier group further includes a first excitation source and a second excitation source, wherein the first excitation source is connected to the first combiner and the second excitation source is connected to the second combiner.

9. The fiber laser according to claim 7, characterized in that, The optical fiber line is provided with a first isolator and a second isolator. The first isolator is located between the coupler and the first combiner, and the second isolator is located at the output end of the second combiner.

10. The fiber laser according to claim 6, characterized in that, The beam splitter has a condenser lens on one side along the direction of the transmitted light, and the condenser lens is located between the beam splitter and the coupler, for focusing the transmitted light into the coupler.

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