Dual-output fiber laser and multimode combined fiber laser

Abstract

The present invention discloses a double-ended output fiber laser, which includes two optical resonators, two gain fibers, and two sets of pump sources. Each optical resonator is composed of a low-reflection grating and a high-reflection grating, and the high-reflection gratings of the two optical resonators are fused together or share the same high-reflection grating. During the operation of the double-ended output fiber laser, on the one hand, the lasers generated by the two optical resonators respectively are transmitted through their respective low-reflection gratings and output through their respective fiber end caps, so as to achieve the simultaneous output of two beams of lasers and improve the output power of the laser; on the other hand, the two optical resonators can mutually use the pump light transmitted by the other through the high-reflection grating, ensuring the full absorption of the pump light and improving the optical-to-optical conversion efficiency of the laser. The present invention also discloses a multi-mode combined fiber laser, and the beam combination sub-module adopts the above-mentioned double-ended output fiber laser, which helps to realize the miniaturization and high efficiency of the multi-mode combined fiber laser system.

Description

Technical Field

[0001] The present invention belongs to the technical field of fiber lasers, and particularly relates to a double-end output fiber laser and a multi-mode combined fiber laser. Background Art

[0002] A fiber laser generally consists of a pump source, a fiber combiner, a reflection grating, a gain fiber, a cladding light filter, and a fiber end cap. The pump source light is combined by the fiber combiner and then injected into the gain fiber. Under the action of an optical resonator composed of two reflection gratings, laser is formed in the gain fiber. After the cladding light is filtered by the cladding light filter, the laser finally outputs through the fiber end cap.

[0003] Currently, the main reason restricting the single-cavity structure fiber laser from hitting higher power is the Raman effect of the gain fiber. Increasing the diameter of the gain fiber and reducing the length of the gain fiber can reduce the Raman effect. However, increasing the diameter of the gain fiber will bring an increase in laser modes, resulting in a decrease in the stability of the laser; reducing the length of the gain fiber will also reduce the optical-optical conversion efficiency of the laser.

[0004] The above factors are the pain points of current high-power fiber lasers and need to be solved urgently. Summary of the Invention

[0005] Aiming at the above problems, the purpose of the present invention is to provide a double-end output fiber laser and a multi-mode combined fiber laser, which can effectively improve the Raman effect of the gain fiber and improve the stability of the laser while increasing the output power of the laser.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] In a first aspect, an embodiment of the present invention provides a double-end output fiber laser, including a first semiconductor laser and a second semiconductor laser, and further including a first fiber end cap, a first cladding light filter, a first fiber combiner, a first low-reflection grating, a first gain fiber, a first high-reflection grating, a second high-reflection grating, a second gain fiber, a second low-reflection grating, a second fiber combiner, a second cladding light filter, and a second fiber end cap that are sequentially connected through a signal transmission fiber; the first semiconductor laser is connected to the first fiber combiner through a pump transmission fiber, and the second semiconductor laser is connected to the second fiber combiner through a pump transmission fiber; the first low-reflection grating and the first high-reflection grating form a first optical resonator, and the second low-reflection grating and the second high-reflection grating form a second optical resonator.

[0008] In a possible implementation, the reflectivities of the first low-reflection grating and the second low-reflection grating are between 5% and 50%; the reflectivities of the first high-reflection grating and the second high-reflection grating are between 50% and 99%.

[0009] In a possible implementation, the laser wavelengths generated by the first optical resonator and the second optical resonator are different.

[0010] In a possible implementation, the laser wavelengths generated by the first optical resonator and the second optical resonator are the same.

[0011] In a possible implementation, the first optical resonator and the second optical resonator share the same water-cooled plate.

[0012] In a possible implementation, it further includes a first power amplification component and / or a second power amplification component. The first power amplification component is disposed between the first fiber end cap and the first cladding light filter, and the second power amplification component is disposed between the second fiber end cap and the second cladding light filter.

[0013] In a possible implementation, the first power amplification component includes a third semiconductor laser, a third fiber combiner, a third gain fiber, and a third cladding light filter that are sequentially connected through a signal transfer fiber. The third semiconductor laser is connected to the third fiber combiner through a pump transfer fiber; the second power amplification component includes a fourth semiconductor laser, a fourth fiber combiner, a fourth gain fiber, and a fourth cladding light filter that are sequentially connected through a signal transfer fiber. The fourth semiconductor laser is connected to the fourth fiber combiner through a pump transfer fiber.

[0014] In a second aspect, an embodiment of the present invention provides another dual-end output fiber laser, including a first semiconductor laser and a second semiconductor laser, and further including a first fiber end cap, a first cladding light filter, a first fiber combiner, a first low-reflection grating, a first gain fiber, a third high-reflection grating, a second gain fiber, a second low-reflection grating, a second fiber combiner, a second cladding light filter, and a second fiber end cap that are sequentially connected through a signal transfer fiber; the first semiconductor laser is connected to the first fiber combiner through a pump transfer fiber, and the second semiconductor laser is connected to the second fiber combiner through a pump transfer fiber; the first low-reflection grating and the third high-reflection grating form a first optical resonator, and the second low-reflection grating and the third high-reflection grating form a second optical resonator.

[0015] In a possible implementation, the reflectivity of the first low-reflection grating and the second low-reflection grating is between 5% and 50%; the reflectivity of the third high-reflection grating is between 50% and 99%.

[0016] In a third aspect, an embodiment of the present invention provides a multimode combined fiber laser, which includes a plurality of combined sub-modules, and the combined sub-module adopts the above-mentioned double-ended output fiber laser.

[0017] The advantages and beneficial effects of the present invention are as follows:

[0018] The two double-ended output fiber lasers provided by the embodiments of the present invention both include two optical resonators, two gain fibers, and two sets of pump sources. On the one hand, the lasers generated by the two optical resonators respectively can be transmitted through their respective low-reflection gratings and output through their respective fiber end caps, realizing the simultaneous output of two lasers, improving the output power of the laser. In this way, when ensuring the same output power of the laser, the length of the gain fiber of a single optical resonator can be shortened, the power density in the cavity can be reduced, the Raman effect of the gain fiber can be improved, and the stability of the laser can be enhanced; on the other hand, the high-reflection gratings of the two optical resonators are connected to each other, and the pump light transmitted through the high-reflection grating in one optical resonator can be injected into the other optical resonator, enabling the two optical resonators to share the pump light transmitted through each other, ensuring the full absorption of the pump light, and improving the optical-to-optical conversion efficiency of the laser.

[0019] For the multimode combined fiber laser provided by the embodiments of the present invention, the combined sub-module adopts the above-mentioned double-ended output fiber laser, which helps to realize the miniaturization and high efficiency of the multimode combined fiber laser system.

[0020] Other features and advantages of the present invention will be described in the subsequent description, and part of them will become obvious from the description or be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained by the structures specifically pointed out in the written description and the drawings.

[0021] The technical solutions of the present invention will be further described in detail below through the drawings and embodiments. Description of the Drawings

[0022] The drawings are used to provide a further understanding of the present invention, and constitute a part of the description. They are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention. In the drawings:

[0023] Figure 1 It is a schematic structural diagram of a double-ended output fiber laser provided by an embodiment of the present invention;

[0024] Figure 2Schematic diagram of a double-ended output fiber laser with a power amplification component provided in an embodiment of the present invention;

[0025] Figure 3 Schematic diagram of another double-ended output fiber laser provided in an embodiment of the present invention.

[0026] In the drawings: 1 - first fiber end cap; 2 - first cladding light filter; 3 - first fiber combiner; 4 - first low-reflection grating; 5 - first gain fiber; 6 - first high-reflection grating; 7 - second high-reflection grating; 8 - second gain fiber; 9 - second low-reflection grating; 10 - second fiber combiner; 11 - second cladding light filter; 12 - second fiber end cap; 13 - first semiconductor laser; 14 - second semiconductor laser; 15 - third fiber combiner; 16 - third semiconductor laser; 17 - third gain fiber; 18 - third cladding light filter; 19 - fourth fiber combiner; 20 - fourth semiconductor laser; 21 - fourth gain fiber; 22 - fourth cladding light filter; 30 - third high-reflection grating. Detailed implementation manners

[0027] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0028] In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more, unless otherwise specifically defined.

[0029] In the present invention, unless otherwise clearly specified and limited, terms such as "installed", "connected", "connected to", "fixed" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0030] The present invention discloses a double-ended output fiber laser, which includes two optical resonators, two gain fibers, and two sets of pump sources. Each optical resonator is composed of a low-reflection grating and a high-reflection grating, and the high-reflection gratings of the two optical resonators are fused together or share the same high-reflection grating. During the operation of the double-ended output fiber laser, on the one hand, the lasers generated by the two optical resonators respectively are transmitted through their respective low-reflection gratings and output through their respective fiber end caps, enabling the simultaneous output of two lasers and increasing the output power of the laser. On the other hand, the two optical resonators can mutually use the pump light transmitted by the other through the high-reflection grating, ensuring the full absorption of the pump light and improving the optical-to-optical conversion efficiency of the laser.

[0031] The following describes the preferred embodiments of the present invention with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only for the purpose of illustrating and explaining the present invention and are not intended to limit the present invention.

[0032] Embodiment 1

[0033] See Figure 1 As shown, the double-ended output fiber laser provided in Embodiment 1 of the present invention includes a first semiconductor laser 13 and a second semiconductor laser 14, and further includes a first fiber end cap 1, a first cladding light filter 2, a first fiber combiner 3, a first low-reflection grating 4, a first gain fiber 5, a first high-reflection grating 6, a second high-reflection grating 7, a second gain fiber 8, a second low-reflection grating 9, a second fiber combiner 10, a second cladding light filter 11, and a second fiber end cap 12 that are sequentially connected through a signal transmission fiber; the first semiconductor laser 13 is connected to the first fiber combiner 3 through a pump transmission fiber, and the second semiconductor laser is connected to the second fiber combiner 10 through a pump transmission fiber; wherein, the first low-reflection grating 4 and the first high-reflection grating 6 constitute a first optical resonator, and the second low-reflection grating 9 and the second high-reflection grating 7 constitute a second optical resonator.

[0034] It can be seen from Figure 1 that the double-ended output fiber laser provided in Embodiment 1 of the present invention includes two optical resonators, two gain fibers, and two sets of pump sources, and the high-reflection gratings of the two optical resonators are fused together with each other.

[0035] On the one hand, during the operation of the double-ended output fiber laser, the lasers generated by the two optical resonators respectively are transmitted through their respective low-reflection gratings and output through their respective fiber end caps, enabling the simultaneous output of two lasers and increasing the output power of the laser. In this way, when ensuring the same output power of the laser, the length of the gain fiber of a single optical resonator can be shortened, the power density in the cavity can be reduced, the Raman effect of the gain fiber can be improved, and the stability of the laser can be enhanced.

[0036] Specifically, the pump light generated by the first semiconductor laser 13 is injected into the first fiber combiner 3 through the pump energy transfer fiber, and then injected into the first optical resonator from the first low-reflection grating 4 end through the signal energy transfer fiber. Under the excitation of the pump light and the action of the resonator, the first gain fiber 5 generates the first laser. The first laser transmits through the first low-reflection grating 4, and after passing through the first fiber combiner 3 and the first cladding light filter 2 in sequence, it is output from the first fiber end cap 1. Similarly, the pump light generated by the second semiconductor laser 14 is injected into the second fiber combiner 10 through the pump energy transfer fiber, and then injected into the second optical resonator from the second low-reflection grating 9 end through the signal energy transfer fiber. Under the excitation of the pump light and the action of the resonator, the second gain fiber 8 generates the second laser. The second laser transmits through the second low-reflection grating 9, and after passing through the second fiber combiner 10 and the second cladding light filter 11 in sequence, it is output from the second fiber end cap 12.

[0037] Taking the example that a single laser requires 40 m of gain fiber, if the dual-output fiber laser of Embodiment 1 of the present invention is adopted, when ensuring the same output power of the laser, the lengths of the gain fibers in the two optical resonators can both be 20 m. By using 40 m of gain fiber in the two optical resonators together, the length of a single optical resonator is greatly reduced, and the Raman effect of the gain fiber can be effectively improved.

[0038] On the other hand, during the operation of the dual-output fiber laser, the pump light transmitted through the first high-reflection grating 6 in the first optical resonator can be injected into the second optical resonator, and the pump light transmitted through the second high-reflection grating 7 in the second optical resonator can be injected into the first optical resonator, enabling the two optical resonators to mutually use the pump light transmitted by each other, ensuring the full absorption of the pump light, and improving the optical-to-optical conversion efficiency of the laser.

[0039] It can be understood that the two low-reflection gratings in Embodiment 1 of the present invention are both reflection devices and output coupling devices of the optical resonator, and their fiber core diameters are both matched with the diameter of the signal energy transfer fiber. The two low-reflection gratings partially reflect the laser generated by the gain fiber back into the optical resonator and partially transmit it out of the optical resonator, enabling the simultaneous output of two lasers and increasing the output power of the laser. The two high-reflection gratings in Embodiment 1 of the present invention are mainly used as reflection devices of the optical resonator, and can also be output coupling devices, and their fiber core diameters are matched with each other. By fusing the two high-reflection gratings together at the end not connected to the gain fiber, the pump light that cannot be absorbed by one optical resonator can enter the other optical resonator through the high-reflection grating and be absorbed again, ensuring the full absorption of the pump light and improving the optical-to-optical conversion efficiency of the laser.

[0040] The grating reflectivity affects the laser power fed back into the optical resonator and thus affects the laser output power. Excessive laser power in the optical resonator can trigger stimulated Raman scattering (SRS), and the occurrence of SRS limits the increase in the output power of the laser. In the preferred embodiment, the reflectivities of the first low-reflection grating 4 and the second low-reflection grating 9 are selected to be between 5% and 50%, and the reflectivities of the first high-reflection grating 6 and the second high-reflection grating 7 are selected to be between 50% and 99%. When selecting the grating reflectivity, it is necessary to comprehensively consider the output power of the laser and the Raman effect, and minimize the Raman effect as much as possible on the premise that the output power of the laser meets the requirements, so as to improve the stability of the laser.

[0041] The central wavelengths of the gratings on both sides of the optical resonator need to match to achieve laser oscillation and laser output. The laser wavelength generated by the optical resonator is jointly determined by the gain fiber and the central wavelengths of the gratings on both sides. The laser wavelengths generated by the two optical resonators in Embodiment 1 of the present invention can be the same or different. For example, the central wavelength matched by the first low-reflection grating 4 and the first high-reflection grating 6 is L1, and the central wavelength matched by the second low-reflection grating 9 and the second high-reflection grating 7 is L2. If L1 is equal to L2, the laser wavelengths generated by the first optical resonator and the second optical resonator are the same; if L1 is not equal to L2, the laser wavelengths generated by the first optical resonator and the second optical resonator are different.

[0042] The dual-output fiber laser in Embodiment 1 of the present invention can output single-wavelength laser or dual-wavelength laser according to application needs. For example, in power combining applications, the lasers with the same wavelength can be generated by controlling the two optical resonators. Compared with a fiber laser with only one optical resonator of the same power, when combining the power of the lasers with the same wavelength output from both ends, it is beneficial to reduce the power density in the transmission fiber, reduce the Raman effect during high-power laser output, and further reduce the impact of the Raman effect on the increase in output power, thereby achieving higher laser power output. However, in some other applications, such as fiber sensing, optical device testing, optical wavelength division multiplexing systems, terahertz wave generation, etc., the lasers with different wavelengths can be generated by controlling the two optical resonators.

[0043] The gain fiber used in Embodiment 1 of the present invention is a gain fiber doped with rare earth ions, which can be used for the generation and transmission of laser. The cross-sectional structure of the gain fiber is selected from one of the cross-sectional structures of double-clad or triple-clad fiber; rare earth ions are doped in the core for generating laser, and no rare earth ions are doped in the cladding for transmitting pump light. The length of the gain fiber is determined according to the design of the laser. The lengths of the gain fibers in the two optical resonators can be the same or different. Moreover, the model parameters of the gain fibers in the two optical resonators can be the same or different. The present invention does not limit the length and model parameters of the gain fiber.

[0044] The semiconductor laser used in Embodiment 1 of the present invention is an excitation source that can generate upper-level particles in the gain fiber, and it includes semiconductor lasers in multiple bands that match the absorption peak of the gain fiber. The signal energy transmission fiber is a non-rare-earth-ion-doped fiber for laser transmission, and its cross-sectional structure is a double-clad or triple-clad structure. The pump energy transmission fiber is a non-rare-earth-ion-doped fiber for pump laser transmission, and its structure is mostly a double-clad structure at present. Its advantage is that it does not need to directly couple the pump energy into the fiber with a relatively small mode field diameter, and it is more suitable for using low-cost large-mode-field (multimode) high-power semiconductor lasers.

[0045] For the fiber combiner used in Embodiment 1 of the present invention, the signal laser can be transmitted with low loss in both forward and reverse directions, and the pump light can be transmitted with low loss in the forward direction. The way of injecting the pump light into the fiber combiner can be end pumping, side pumping, and other pumping methods. Among them, end pumping is to couple one or more beams of pump light into the fiber end face; side pumping is to couple the pump light to one side of the fiber and then couple it into the inner cladding of the fiber through a coupler.

[0046] The cladding light filter used in Embodiment 1 of the present invention can filter out the residual pump light and high-order modes in the signal fiber, and its geometric size is the same as that of the signal energy transmission fiber. The fiber end cap used in the embodiment of the present invention can expand the beam of the signal light in the signal energy transmission fiber and output it, reduce the power density of the output end face, and improve the reliability of the laser.

[0047] In summary, the double-end output fiber laser provided in Embodiment 1 of the present invention includes two optical resonators, two gain fibers, and two sets of pump sources. On the one hand, the lasers generated by the two optical resonators are transmitted through their respective low-reflection gratings and output through their respective fiber end caps, which can realize the simultaneous output of two beams of laser, improve the output power of the laser. In this way, when ensuring the same output power of the laser, the length of the gain fiber in a single optical resonator can be shortened, the power density in the cavity can be reduced, the Raman effect of the gain fiber can be improved, and the stability of the laser can be enhanced; on the other hand, the high-reflection gratings of the two optical resonators are connected to each other, so that the two optical resonators can share the pump light transmitted by each other, ensuring the full absorption of the pump light and improving the optical-to-optical conversion efficiency of the laser.

[0048] In addition, the dual-output fiber laser of Embodiment 1 of the present invention realizes the power output of two traditional lasers in an all-fiber laser system composed of a set of optical components, a driving power supply, and a control module, which can reduce the volume, weight, and material cost of the laser. The two laser output heads can be synchronously used in two cutting machines, which helps to improve the utilization rate of the laser and the cutting efficiency. The water-cooled plate for coiling the optical fiber can be one piece or multiple pieces spliced together. When the two optical resonators share the same water-cooled plate, for example, the two optical resonators are respectively placed on the front and back sides of the same water-cooled plate, the volume, weight, and material cost of the laser can be further reduced.

[0049] Embodiment 2

[0050] To further improve the output power of the laser, as shown in Figure 2 The dual-output fiber laser provided in Embodiment 2 of the present invention may further include a first power amplification component and / or a second power amplification component on the basis of Embodiment 1 above, wherein the first power amplification component is disposed between the first fiber end cap 1 and the first cladding light filter 2, and the second power amplification component is disposed between the second fiber end cap 12 and the second cladding light filter 11.

[0051] It is easy to understand that according to the requirement of the laser power output, only the laser output from one end can be power-amplified. For example, only the first power amplification component is disposed between the first fiber end cap 1 and the first cladding light filter 2, or only the second power amplification component is disposed between the second fiber end cap 12 and the second cladding light filter 11. Of course, when necessary, the lasers output from both ends can be power-amplified simultaneously, and in this case, both the first power amplification component and the second power amplification component need to be disposed.

[0052] Further referring to Figure 2 As shown, the first power amplification component includes a third semiconductor laser 16 and a third fiber combiner 15, a third gain fiber 17, and a third cladding light filter 18 that are sequentially connected through a signal transfer optical fiber, and the third semiconductor laser 16 is connected to the third fiber combiner 15 through a pump transfer optical fiber. The second power amplification component includes a fourth semiconductor laser 20 and a fourth fiber combiner 19, a fourth gain fiber 21, and a fourth cladding light filter 22 that are sequentially connected through a signal transfer optical fiber, and the fourth semiconductor laser 20 is connected to the fourth fiber combiner 19 through a pump transfer optical fiber.

[0053] Among them, the third fiber combiner 15 and the fourth fiber combiner 19 can be a forward combiner or a reverse combiner. Taking the first power amplification component as an example, Figure 2The third fiber optic combiner 15 shown is set as a reverse combiner. The pump light generated by the third semiconductor laser 16 is combined by the third fiber optic combiner 15 and then transmitted reversely to the third gain fiber 17. The laser generated by the first optical resonator serves as the seed laser, which is output to the third gain fiber 17 via the third fiber optic combiner 15. The seed laser entering the third gain fiber 17 is amplified in power under the excitation of the pump light, and a laser with a higher output power density is output. Then, after the residual pump light and high-order modes are filtered out by the third cladding light filter 18, it is output by the first fiber end cap 1.

[0054] For the first power amplification component and the second power amplification component in Embodiment 2 of the present invention, a Master Oscillator Power Amplifier (MOPA) structure is adopted. The laser output from one end or both ends of Embodiment 2 of the present invention can be power-amplified to meet the application requirements in the aspect of kilowatt-level high power.

[0055] Embodiment 3

[0056] See Figure 3 As shown, the dual-output fiber laser provided in Embodiment 3 of the present invention includes a first semiconductor laser 13 and a second semiconductor laser 14, and further includes a first fiber end cap 1, a first cladding light filter 2, a first fiber optic combiner 3, a first low-reflection grating 4, a first gain fiber 5, a third high-reflection grating 30, a second gain fiber 8, a second low-reflection grating 9, a second fiber optic combiner 10, a second cladding light filter 11, and a second fiber end cap 12 that are sequentially connected through a signal transmission fiber; the first semiconductor laser 13 is connected to the first fiber optic combiner 3 through a pump transmission fiber, and the second semiconductor laser is connected to the second fiber optic combiner 10 through a pump transmission fiber; wherein, the first low-reflection grating 4 and the third high-reflection grating 30 form a first optical resonator, and the second low-reflection grating 9 and the third high-reflection grating 30 form a second optical resonator.

[0057] It can be seen from Figure 3 that the dual-output fiber laser provided in Embodiment 3 of the present invention includes two optical resonators, two gain fibers, and two sets of pump sources, and the two optical resonators share the same high-reflection grating.

[0058] When selecting the grating reflectivity, the output power and Raman effect of the laser need to be comprehensively considered. In a preferred embodiment, the reflectivities of the first low-reflection grating 4 and the second low-reflection grating 9 are selected between 5% and 50%, and the reflectivity of the third high-reflection grating 30 is selected between 50% and 99%, which can reduce the Raman effect and improve the laser stability while ensuring that the output power of the laser meets the requirements.

[0059] In the solution of Embodiment 3 of the present invention, the laser wavelengths generated by the first optical resonator and the second optical resonator are the same, and the laser wavelengths of the double-end output are basically the same. This is because the laser wavelength is jointly determined by the gain fiber, the central wavelengths of the high-reflection grating and the low-reflection grating. In the solution of Embodiment 3 of the present invention, there is only one high-reflection grating, and the central wavelengths of the two low-reflection gratings need to be the same as the central wavelength of this high-reflection grating, so that the laser wavelengths generated by the first optical resonator and the second optical resonator are the same.

[0060] Similar to Embodiment 1 above, during the operation of the double-end output fiber laser of Embodiment 3 of the present invention: on the one hand, the lasers generated by the two optical resonators are transmitted through their respective low-reflection gratings and output through their respective fiber end caps, enabling the simultaneous output of two lasers, improving the output power of the laser. In this way, while ensuring the same output power of the laser, the length of the gain fiber of a single optical resonator can be shortened, the power density in the cavity can be reduced, the Raman effect of the gain fiber can be improved, and the stability of the laser can be enhanced. On the other hand, the pump light transmitted through the third high-reflection grating 30 in the first optical resonator can be injected into the second optical resonator, and the pump light transmitted through the third high-reflection grating 30 in the second optical resonator can be injected into the first optical resonator, enabling the two optical resonators to share the pump light transmitted by each other, ensuring the full absorption of the pump light, and improving the optical-to-optical conversion efficiency of the laser.

[0061] Compared with the solution of fusing two high-reflection gratings in Embodiment 1 above, since only one high-reflection grating is used in Embodiment 3 of the present invention, compared with Embodiment 1 above, one high-reflection grating is reduced, which can save device costs; the optical-to-optical conversion efficiency will be slightly reduced by 3%-5% compared with the non-shared high-reflection grating solution in Embodiment 1 above, but it is still sufficient to meet the actual laser power output.

[0062] Embodiment 4

[0063] Embodiment 4 of the present invention provides a multimode combined fiber laser, which includes a plurality of combined sub-modules, and these combined sub-modules adopt the double-end output fiber lasers of the above Embodiments 1-3.

[0064] The multimode combined fiber laser is currently the main way to improve the laser output power. It combines multiple low-power combined sub-modules through a signal combiner to achieve high-power laser output. Therefore, the multimode combined fiber laser needs to be composed of multiple low-power combined sub-modules. By improving the power and efficiency of each combined sub-module, it will be beneficial to improve the power and efficiency of the multimode combined fiber laser.

[0065] As described above, the dual-output fiber lasers of Embodiments 1-3 of the present invention can improve the output power and optical-to-optical conversion efficiency of the laser. By applying the dual-output fiber lasers of the above Embodiments 1-3 as beam combining sub-modules (the two output end caps need to be removed) to Embodiment 4 of the present invention, the power and efficiency of the multi-mode beam combining fiber laser can be improved, which helps to realize the miniaturization and high efficiency of the multi-mode beam combining fiber laser system.

[0066] In a preferred embodiment, the two optical resonators of the dual-output fiber laser serving as the beam combining sub-module are controlled to generate lasers of the same wavelength. In this way, compared with a fiber laser with only one resonator of the same power, when the lasers of the same wavelength are output from both ends and combined in power, it is beneficial to reduce the power density in the transmission fiber, reduce the Raman effect during high-power laser output, and further reduce the influence of the Raman effect on the improvement of the output power, thereby achieving a higher laser power output.

[0067] The above are only specific embodiments of the present invention. Under the above teachings of the present invention, those skilled in the art can make other improvements or deformations based on the above embodiments. Those skilled in the art should understand that the above specific description is only a better explanation of the purpose of the present invention. Those skilled in the art can make various changes and deformations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and deformations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these changes and deformations.

Claims

1. A dual-output fiber laser, characterized in that, It includes a first semiconductor laser and a second semiconductor laser, and also includes a first fiber end cap, a first cladding light filter, a first fiber combiner, a first low-reflection grating, a first gain fiber, a first high-reflection grating, a second high-reflection grating, a second gain fiber, a second low-reflection grating, a second fiber combiner, a second cladding light filter, and a second fiber end cap that are sequentially connected through a signal transmission optical fiber; the first semiconductor laser is connected to the first fiber combiner through a pump transmission optical fiber, and the second semiconductor laser is connected to the second fiber combiner through a pump transmission optical fiber; the first low-reflection grating and the first high-reflection grating form a first optical resonator, and the second low-reflection grating and the second high-reflection grating form a second optical resonator; The pump light generated by the first semiconductor laser is injected into the first fiber combiner through the pump transmission optical fiber, and then injected into the first optical resonator from the first low-reflection grating end through the signal transmission optical fiber. Under the excitation of the pump light and the action of the resonator, the first gain fiber generates first laser light. The first laser light transmits through the first low-reflection grating, and after passing through the first fiber combiner and the first cladding light filter in sequence, it is output by the first fiber end cap; The pump light generated by the second semiconductor laser is injected into the second fiber combiner through the pump transmission optical fiber, and then injected into the second optical resonator from the second low-reflection grating end through the signal transmission optical fiber. Under the excitation of the pump light and the action of the resonator, the second gain fiber generates second laser light. The second laser light transmits through the second low-reflection grating, and after passing through the second fiber combiner and the second cladding light filter in sequence, it is output by the second fiber end cap, realizing the simultaneous output of two-way laser light; The pump light transmitted through the first high-reflection grating in the first optical resonator is injected into the second optical resonator, and the pump light transmitted through the second high-reflection grating in the second optical resonator is injected into the first optical resonator, realizing the mutual use of the pump light transmitted through each other by the two optical resonators.

2. The dual-output fiber laser according to claim 1, wherein, The reflectivity of the first low-reflection grating and the second low-reflection grating is between 5% and 50%; the reflectivity of the first high-reflection grating and the second high-reflection grating is between 50% and 99%.

3. The double-ended output fiber laser according to claim 1, characterized in that, The laser wavelengths generated by the first optical resonator and the second optical resonator are different.

4. The double-ended output fiber laser according to claim 1, wherein The laser wavelengths generated by the first optical resonator and the second optical resonator are the same.

5. The double-ended output fiber laser according to claim 1, wherein, The first optical resonator and the second optical resonator share the same water-cooling plate.

6. The double-ended output fiber laser according to any one of claims 1-5, characterized in that, It also includes a first power amplification component and / or a second power amplification component. The first power amplification component is arranged between the first fiber end cap and the first cladding light filter, and the second power amplification component is arranged between the second fiber end cap and the second cladding light filter.

7. The dual-output fiber laser according to claim 6, wherein The first power amplification component includes a third semiconductor laser and a third fiber combiner, a third gain fiber, and a third cladding light filter that are sequentially connected through a signal transmission optical fiber. The third semiconductor laser is connected to the third fiber combiner through a pump transmission optical fiber; The second power amplification component includes a fourth semiconductor laser, a fourth fiber combiner, a fourth gain fiber, and a fourth cladding light filter connected in sequence through a signal energy transmission fiber, and the fourth semiconductor laser is connected to the fourth fiber combiner through a pump energy transmission fiber.

8. A double-ended output fiber laser, characterized in that, It includes a first semiconductor laser and a second semiconductor laser, and further includes a first fiber end cap, a first cladding light filter, a first fiber combiner, a first low-reflection grating, a first gain fiber, a third high-reflection grating, a second gain fiber, a second low-reflection grating, a second fiber combiner, a second cladding light filter, and a second fiber end cap connected in sequence through a signal energy transmission fiber; the first semiconductor laser is connected to the first fiber combiner through a pump energy transmission fiber, and the second semiconductor laser is connected to the second fiber combiner through a pump energy transmission fiber; the first low-reflection grating and the third high-reflection grating form a first optical resonant cavity, and the second low-reflection grating and the third high-reflection grating form a second optical resonant cavity.

9. The double-ended output fiber laser according to claim 8, wherein The reflectivities of the first low-reflection grating and the second low-reflection grating are between 5% and 50%; the reflectivity of the third high-reflection grating is between 50% and 99%.

10. A multimode combined fiber laser, comprising a plurality of combined sub-modules, characterized in that, The beam combining sub-module uses the double-ended output fiber laser according to any one of claims 1-9.

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