Single-fiber one-hundred-thousand-watt-level fiber laser based on auxiliary laser and cladding composite pumping

Abstract

The application discloses a single-fiber 100-kilowatt-level fiber laser based on auxiliary laser and cladding composite pumping, multi-wavelength auxiliary laser and signal laser are simultaneously injected into a gain fiber core, and the gain fiber provides gain for the auxiliary laser and the signal laser under multi-wavelength cladding pumping. The multi-wavelength auxiliary laser and the signal laser are amplified in turn under the action of gain competition, so that the amplification efficiency of the signal laser in the front section of the gain fiber is inhibited, and in the rear section of the gain fiber, the signal laser is effectively amplified after the multi-wavelength auxiliary laser is reabsorbed. In the amplification process, quantum loss is gradually released, so that the heat load in the gain fiber is homogenized, the bearing capacity of laser power is improved, the suppression of mode instability effect is further realized, meanwhile, the existence of gain competition reduces the effective nonlinear effect length of the signal laser, the suppression of nonlinear effect is realized, and 100-kilowatt-level high-power near-diffraction-limited laser output is obtained.

Description

Technical Field

[0001] This invention relates to the field of high-power fiber laser amplification, and more particularly to an amplification technology for a single-fiber 100 MW fiber laser based on auxiliary laser and cladding composite pumping. Background Technology

[0002] Near-diffraction-limited single-fiber high-power fiber lasers have broad application prospects in defense, scientific research, and industrial processing. Improving the output power of single-fiber lasers has always been a research hotspot in the field of high-power fiber laser technology. Single-fiber high-power fiber lasers mainly adopt the master oscillator power amplifier (MOPA) structure. Based on this structure, near-diffraction-limited laser output of up to 20 kW has been reported. With the advancement of fiber fabrication technology and the improvement of pump source brightness, the factors limiting further improvement of fiber MOPA power are mainly thermal load, nonlinear effects, and mode instability (TMI) effects. Among them, nonlinear effects include stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS) effects.

[0003] In high-power fiber optic systems, thermal load is primarily caused by quantum defects during the pump-to-signal conversion process. This thermal load increases the thermal management pressure on fiber laser systems, and the TMI effect under high thermal load leads to a sharp deterioration in laser beam quality. Methods to mitigate fiber thermal effects mainly include optimizing the pump wavelength and reducing the rare-earth ion doping concentration in the fiber. Essentially, both methods optimize the thermal load of the laser system by reducing the absorption efficiency of the pump laser in the gain fiber. However, reducing the pump absorption efficiency means compensating for the laser efficiency by increasing the length of the gain fiber, which in turn lowers the nonlinear threshold.

[0004] In recent years, fiber laser amplification methods based on gain competition have been proposed. These methods select a pump laser in the short wavelength direction and amplify it simultaneously with the signal laser, then reabsorb it in the later stages of the amplifier to continue amplifying the signal laser using in-band pumping. This method can alleviate the thermal load in the initial stage of the amplifier, improving system stability. Furthermore, the smaller quantum defect of the in-band pumping method effectively increases the TMI threshold. Simultaneously, this method effectively reduces the effective nonlinear length of the signal laser, thereby increasing the nonlinear effect threshold. However, there are still significant challenges in selecting the short-wavelength pump laser in this method. Firstly, while a short-wavelength pump laser close to the cladding pump wavelength can reduce the thermal load in the initial stage of the amplifier, it still generates a high temperature peak in the later stage of the amplifier. Furthermore, the strong reabsorption effect will produce severe amplified spontaneous emission (ASE) between the wavelengths of the short-wavelength laser and the signal laser, which cannot be suppressed by the frequency hole-burning effect of the signal laser. If the short-wavelength pump laser is close to the signal laser, it cannot effectively reduce the thermal load in the initial stage of the amplifier. Moreover, due to the decrease in the absorption efficiency of the fiber for the short-wavelength pump laser, the short-wavelength pump laser cannot effectively pump the signal laser. The long fiber length and high pump power in 100 watt-class fiber amplifiers will make the above problems more obvious. If multiple short-wavelength lasers are used as auxiliary lasers, and the laser energy is gradually transferred to the signal laser by means of cascaded gain competition and the relatively long gain fiber length in the high-power laser system, not only can a uniform distribution of thermal load be achieved, but also the thermal load generated by the amplified signal laser can be effectively reduced and the effective nonlinear length can be shortened. On this basis, by combining multi-wavelength cladding pumping, the absorption distribution of the pump laser in the laser system can be optimized, further optimizing the system thermal load and breaking through the power bottleneck of single-fiber lasers.

[0005] In summary, the power improvement of single-fiber high-power fiber amplifiers remains constrained by thermal effects, nonlinear effects, and the TMI effect, posing significant challenges. Optimizing the thermal load of fiber laser systems and reducing the effective length for quantum loss and nonlinear effect accumulation in signal laser amplification through cascaded gain competition methods and multi-wavelength composite pumping is of great significance in overcoming the bottleneck of output power in single-fiber near-diffraction-limited fiber laser amplifiers. Summary of the Invention

[0006] This invention provides a single-fiber 100 MW-level fiber laser based on auxiliary laser and cladding composite pumping. Addressing the challenges of thermal load and nonlinear effects limiting power improvement in single-fiber 10 MW-level fiber lasers, this invention employs multi-wavelength auxiliary laser and cladding composite pumping to achieve a breakthrough in output power. Preferably, one or more pump wavelengths in the multi-wavelength cladding pumping method are located within the absorption band of rare-earth ions, and the cladding pump light propagates within the cladding and is absorbed by the gain fiber. Preferably, there are two or more auxiliary laser wavelengths, which are located within the emission band of rare-earth doped ions and exhibit a certain degree of absorption. Furthermore, in the short wavelength direction of the signal laser, both the auxiliary laser and the signal laser propagate and amplify within the fiber core. Through gain competition, the auxiliary laser is preferentially amplified while the amplification of the signal laser is suppressed. During laser amplification, as the cladding pump light is absorbed and gradually weakens, the auxiliary laser will be gradually absorbed as the pump light for the signal laser in the later section of the fiber, thus enabling the signal laser to be effectively amplified in the later section of the amplifier. This invention can effectively suppress stimulated Raman scattering and mode instability effects, and can achieve a uniform distribution of thermal load in the gain fiber, ensuring the stable operation of high-power fiber lasers. See the description below for details:

[0007] A single-fiber 100 MW-class fiber laser based on auxiliary laser and cladding composite pumping, the laser comprising:

[0008] The center wavelength of the signal laser seed source output is λ S The signal laser, with the first auxiliary laser source, the second auxiliary laser source, ... the Nth auxiliary laser source having output center wavelengths of λ respectively. P1 , λ P2 , λ P3 …λ PN The lasers output from the auxiliary laser, signal laser seed source, first auxiliary laser source, second auxiliary laser source... Nth auxiliary laser source are coupled into the fiber core of the signal input port of the cladding pump light combiner through the laser signal combiner, and then enter the gain fiber.

[0009] The output center wavelengths of the first cladding pump source, the second cladding pump source, the third cladding pump source, ..., the Nth cladding pump source are respectively λ PC1 , λ PC2 …λ PCN The cladding pump laser has a gradually increasing wavelength and is coupled into the cladding of the power amplifier stage fiber through the cladding pump beam combiner.

[0010] The lasers output from the first auxiliary laser source, the second auxiliary laser source, ... the Nth auxiliary laser source and the signal laser seed source are sequentially amplified in the gain fiber. The amplification efficiency of the signal laser output from the signal laser seed source is suppressed in the front section of the gain fiber. As the cladding pump light power decreases, the first auxiliary laser source, the second auxiliary laser source, ... the Nth auxiliary laser source are gradually reabsorbed in the gain fiber. The 1090nm single-mode laser is amplified in the rear section of the gain fiber, and a 100 MW-level near-diffraction-limited 1090nm fiber laser output is obtained after the output cap.

[0011] Wherein, the center wavelength λ of the auxiliary laser source P1 , λ P2 , λ P3 …λ PN It should be located within the laser emission band of the rare-earth doped ions in the gain fiber, with the rare-earth doped ions at the center wavelength λ. P1 , λ P2 , λ P3 …λ PN The absorption and emission cross sections are higher than the center wavelength λ. S The signal laser.

[0012] Furthermore, the center wavelength is λ P1 , λ P2 …λ PN Assisted laser and center wavelength λ s The laser signal is amplified sequentially in the power amplifier stage, with a center wavelength of λ. P1 The smaller wavelength difference between the auxiliary laser and the cladding pump laser reduces the thermal load at the amplifier input. P2 …λ PN Assisted laser and center wavelength λ s When the signal laser is amplified sequentially, the quantum loss generated when each laser wavelength is amplified is reduced, and the thermal load is evenly distributed in the amplifier.

[0013] Furthermore, the center wavelength is λ P1 , λ P2 …λ PN The auxiliary laser is used to core-pump the signal laser at the center wavelength in the back section of the amplifier, reducing the waste heat generated by quantum defect, improving the gain saturation of the system, and achieving an increase in the TMI effect threshold of the signal laser.

[0014] Furthermore, the center wavelength is λ P1 , λ P2 …λ PN The introduction of auxiliary laser suppresses the gain of the center wavelength signal laser in the front end of the amplifier, modulates the gain distribution of the signal laser in the power amplifier stage, shortens the effective nonlinear length of the signal laser, and achieves suppression of nonlinear effects.

[0015] The output power of the signal laser seed source and the first auxiliary laser source, the second auxiliary laser source, ... the Nth auxiliary laser source are individually adjusted to control the energy transfer process of the auxiliary laser and the signal laser in the subsequent power amplification stage.

[0016] Furthermore, the first auxiliary laser source, the second auxiliary laser source... the Nth auxiliary laser source are solid-state lasers, fiber lasers, or semiconductor lasers; the first auxiliary laser source, the second auxiliary laser source... the Nth auxiliary laser source are single-longitudinal-mode lasers or multi-longitudinal-mode lasers; the first auxiliary laser source, the second auxiliary laser source... the Nth auxiliary laser source are single-transverse-mode lasers or higher-order transverse-mode lasers.

[0017] The first cladding pump source, the second cladding pump source, the third cladding pump source... the Nth cladding pump source are in the form of semiconductor lasers, solid-state lasers or fiber lasers.

[0018] Furthermore, the signal laser seed source and auxiliary laser source are in the form of oscillators or amplifiers. The output cap is a laser transmission device used to reduce the power density at the laser output end face.

[0019] The beneficial effects of the technical solution provided by this invention are:

[0020] 1. Based on this technology, it is possible to comprehensively suppress nonlinear effects and TMI effects during high-power amplification, break through the single-fiber power output bottleneck of fiber lasers, and realize high-power fiber laser output at the 100 MW level near diffraction limit.

[0021] 2. This invention can balance the thermal load in high-power fiber amplifiers, achieve uniform temperature distribution, and improve the system's operational stability under high-power conditions;

[0022] 3. The auxiliary laser used in this technique can be effectively absorbed in the later stage of the power amplification stage, thus obtaining a relatively pure signal laser in the output laser without the need for beam splitting;

[0023] 4. The method for suppressing nonlinear effects in this technique does not require special design of the fiber optic system. It only requires optimizing and adjusting the power ratio and wavelength of the laser seed source and the auxiliary laser to effectively suppress nonlinear effects.

[0024] 5. This invention can simultaneously suppress nonlinear effects in high-power fiber laser amplifiers; and achieve near-diffraction-limited laser output at the 100 MW level in a single fiber. Attached Figure Description

[0025] Figure 1This is a schematic diagram of a single-fiber 100 MW fiber laser based on auxiliary laser and cladding composite pumping.

[0026] The attached diagram lists the components represented by each number as follows:

[0027] 1: Signal laser seed source; 2: First auxiliary laser source;

[0028] 3: Second auxiliary laser source; 4: Nth auxiliary laser source;

[0029] 5: Laser signal beam combiner; 6: First cladding pump source;

[0030] 7: Second cladding pump source; 8: Third cladding pump source;

[0031] 9: Nth cladding pump source; 10: Cladding pump beam combiner;

[0032] 11: Gain fiber; 12: Cladding optical stripper;

[0033] 13: Output cap. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below.

[0035] A single-fiber 100 MW-level fiber laser based on auxiliary laser synergistic amplification and cladding composite pumping adopts a master oscillating fiber amplifier structure, including: a signal laser seed source 1, a first auxiliary laser source 2, a second auxiliary laser source 3... an Nth auxiliary laser source 4, a laser signal beam combiner 5, a first cladding pump source 6, a second cladding pump source 7, a third cladding pump source 8... an Nth cladding pump source 9, a cladding pump beam combiner 10, a gain fiber 11, a cladding stripper 12, and an output cap 13.

[0036] In this embodiment of the invention, the center wavelength of the signal laser seed source 1 is λ. S The signal laser, with the first auxiliary laser source 2, the second auxiliary laser source 3, ... the Nth auxiliary laser source 4, outputs center wavelengths λ respectively. P1 , λ P2 , λ P3 …λ PNThe auxiliary lasers, signal laser seed source 1, first auxiliary laser source 2, second auxiliary laser source 3... Nth auxiliary laser source 4, output lasers are coupled through laser signal combiner 5 into the fiber core of the signal input port of cladding pump beam combiner 10, and then into gain fiber 11. The output power of signal laser seed source 1 and first auxiliary laser source 2, second auxiliary laser source 3... Nth auxiliary laser source 4 can be individually adjusted to control the energy transfer process of auxiliary lasers and signal lasers in subsequent power amplification stages. The output center wavelengths of first cladding pump source 6, second cladding pump source 7, third cladding pump source 8... Nth cladding pump source 9 are λ... PC1 , λ PC2 …λ PCN The cladding pump laser has a gradually increasing wavelength and is coupled into the cladding of the power amplifier stage fiber through the cladding pump beam combiner 10.

[0037] In this embodiment of the invention, the center wavelengths are respectively λ s The signal laser and the center wavelength are respectively λ P1 , λ P2 …λ PN The auxiliary laser in the power amplifier stage first changes with the center wavelength λ. PC1 , λ PC2 …λ PCN The cladding pump laser is injected and simultaneously amplified. Due to the gain competition effect, the wavelength is λ. P1 The auxiliary laser is first amplified in the main power amplifier stage, at which time the wavelength is λ. P2 …λ PN The auxiliary laser and wavelength λ s The amplification of the laser signal is suppressed; as the laser propagates and the cladding pump power decreases, the wavelength λ... P1 The auxiliary laser is reabsorbed, and the wavelength is λ. P2 The auxiliary laser begins to be amplified, and the laser energy is transferred to λ. P2 The auxiliary laser, and then the wavelength is λ P2 The auxiliary laser continues to be reabsorbed, gradually transferring energy to the center wavelength λ. PN The auxiliary laser, during which the signal laser is always in a state of power amplification and suppression, when the center wavelength is λ PN When the auxiliary laser is reabsorbed, the signal laser begins to be effectively amplified, due to the wavelength λ of the signal laser. s Greater than λ P1 , λ P2 …λ PN Therefore, in the power amplifier stage, the laser energy is ultimately transferred to the signal laser, and the signal laser can be effectively amplified when all the auxiliary laser is effectively absorbed.

[0038] In this embodiment of the invention, the center wavelength of the auxiliary laser should be within the laser emission band of the rare earth doped ions in the gain fiber. At the same time, the absorption and emission cross sections of the rare earth doped ions in the active fiber at these wavelengths should be higher than the center wavelength of the signal laser. This ensures that the gain is effectively extracted in the pre-amplification stage to suppress the signal laser, and that the laser energy is reabsorbed in the post-amplification stage, so that the laser energy is transferred to the signal laser.

[0039] In this embodiment of the invention, taking a ytterbium-doped fiber amplifier as an example, considering the special characteristics of high-power fiber amplifiers, the center wavelength λ of the signal laser... s The preferred wavelength is 1060-1090nm. The wavelength range of the auxiliary laser is 1010nm-1090nm, and the longest wavelength of the auxiliary laser should be shorter than the center wavelength of the signal laser.

[0040] In this embodiment of the invention, considering the transmission of cladding pump light within the inner cladding, the rare-earth ions in the gain fiber should have a high absorption cross-section at the center wavelength of the cladding pump light. Taking a ytterbium-doped fiber amplifier as an example, the center wavelength of the cladding pump light is selected between three bands: 915nm±5nm, 976nm±5nm, and 940nm±5nm, to ensure the absorption of the cladding pump laser by the gain fiber.

[0041] The principle of balancing the heat load in this embodiment of the invention is as follows: the center wavelength is λ P1 , λ P2 …λ PN Assisted laser and center wavelength λ s The laser signal is effectively amplified sequentially in the power amplifier stage, with a center wavelength of λ. P1 The small wavelength difference between the auxiliary laser and the cladding pump laser effectively reduces the thermal load at the amplifier input. P2 …λ PN Assisted laser and center wavelength λ s When the signal laser is amplified sequentially, the in-band pumping method provides more laser gain, which can greatly reduce the quantum loss generated when each laser wavelength is amplified, so that the thermal load is evenly distributed in the amplifier.

[0042] The principle for suppressing the TMI effect in this embodiment of the invention is as follows: the center wavelength is λ s When the signal laser is effectively amplified in the later stage of the amplifier, most of its laser energy comes from the auxiliary laser. The pumping method is in-band pumping, which reduces the quantum defect generated by the amplified signal laser and thus reduces the waste heat generated in the amplifier. Furthermore, the weak absorption of the auxiliary laser in the gain fiber can effectively improve the gain saturation effect in the power amplifier, thereby suppressing the TMI effect.

[0043] The principle of suppressing the SRS effect in this embodiment of the invention is as follows: by using gain competition, the center wavelength λ is effectively suppressed. s The amplification efficiency of the signal laser in the front end of the power amplifier is reduced, thus shortening the effective accumulation length of the nonlinear effect in the power amplifier stage, thereby enabling the suppression of SRS.

[0044] Among them, the total power of the signal laser seed source 1, the first auxiliary laser source 2, the second auxiliary laser source 3... the Nth auxiliary laser source 4 must meet the conditions for effective extraction of energy level ions on the gain fiber.

[0045] The power ratio of the signal laser seed source 1, the first auxiliary laser source 2, the second auxiliary laser source 3... the Nth auxiliary laser source 4 can be freely adjusted according to the length of the amplifier gain fiber, the doping concentration, and the target amplification power, as long as the auxiliary laser is ultimately effectively absorbed.

[0046] Among them, the output cap 13 is a laser transmission device used to reduce the power density of the laser output end face and prevent system damage.

[0047] Example 1

[0048] A single-fiber 100 MW fiber laser based on auxiliary laser and cladding composite pumping, see [link to relevant documentation]. Figure 1As shown, it includes: a signal laser seed source 1 with a center wavelength of 1090nm, which is a single-mode fiber amplifier (maximum output power 50W) with an output pigtail size of 10 / 130μm; a first auxiliary laser source 2 with a center wavelength of 1020nm, which is a single-mode fiber amplifier (maximum output power 100W) with an output pigtail size of 10 / 130μm; a second auxiliary laser source 3 with a center wavelength of 1040nm, which is a single-mode fiber amplifier (maximum output power 100W) with an output pigtail size of 10 / 130μm; a third auxiliary laser source 4 with a center wavelength of 1060nm, which is a single-mode fiber amplifier (maximum output power 200W) with an output pigtail size of 10 / 130μm; and a laser signal combiner 5, which is a 4×1 signal combiner with input pigtail sizes of 10μm and 10 / 130μm. The fiber has an input signal fiber size of 20 / 130μm and an output signal fiber size of 100 / 400 / 480μm. The first cladding pump source 6 is a 981nm pump source, a high-power pump source achieved through semiconductor laser beam combining; the second cladding pump source 7 is a 976nm pump source, a high-power pump source achieved through semiconductor laser beam combining; the third cladding pump source 8 is a 940nm pump source, a high-power pump source achieved through semiconductor laser beam combining; the fourth cladding pump source 9 is a 915nm pump source, a high-power pump source achieved through semiconductor laser beam combining; the (18+1)×1 cladding pump beam combiner 10 has an input signal fiber size of 20 / 130μm and an output signal fiber that is a triple-clad fiber with dimensions of 100 / 400 / 480μm, internally integrating a mode field matcher to suppress the generation of higher-order modes; the gain fiber 11 is Yb-doped. 3+ Triple-clad optical fiber with dimensions of 100 / 400 / 480μm; cladding optical stripper 12 with optical fiber dimensions of 100 / 400 / 480μm; output end cap 13 with pigtail dimensions of 100 / 400 / 480μm.

[0049] The signal laser seed source 1, the first auxiliary laser source 2, the second auxiliary laser source 3... and the third auxiliary laser source 4 enter the core of the output pigtail through the laser signal combiner 5; then they are coupled into the core of the gain fiber 11 through the (18+1)×1 cladding pump light combiner 10; the first cladding pump source to the 18th cladding pump source are all coupled into the inner cladding of the gain fiber 11 through the (18+1)×1 cladding pump light combiner 10.

[0050] The gain fiber 11 has a total length of 20m and a cladding absorption coefficient of 7.5dB / m at 915nm. The lasers output from the first auxiliary laser source 2, the second auxiliary laser source 3…the Nth auxiliary laser source 4, and the signal laser seed source 1 are sequentially amplified within the gain fiber 11. The amplification efficiency of the signal laser output from the signal laser seed source 1 is suppressed in the front section of the gain fiber 11; as the cladding pump power decreases, the auxiliary lasers are gradually reabsorbed in the gain fiber 11, resulting in effective amplification of the 1090nm single-mode laser in the rear section of the gain fiber 11. This leads to a near-diffraction-limited 1090nm fiber laser output at the output cap 13, reaching a power output of 100 kilowatts.

[0051] Example 2

[0052] In this embodiment of the invention, the rare earth ions in the active optical fiber of the gain fiber 11 can be ytterbium ions, thulium ions, holmium ions, neodymium ions, etc.

[0053] In this embodiment of the invention, the selection of the signal laser and auxiliary laser wavelengths for active optical fibers doped with different rare earth ions is only required to meet the concept of the invention, and this embodiment of the invention does not impose any restrictions on this.

[0054] In this embodiment of the invention, the first auxiliary laser source 2, the second auxiliary laser source 3... the Nth auxiliary laser source 4 can be in the form of a solid-state laser, a fiber laser, a semiconductor laser, etc., as long as it can generate laser light of that wavelength; it can be a single longitudinal mode laser or a multi-longitudinal mode laser; it can be a single transverse mode laser or a higher-order transverse mode laser, as long as it can be coupled into a fiber laser system for transmission, amplification, and absorption. This embodiment of the invention does not limit the model, type, etc. of the above-mentioned devices.

[0055] In this embodiment of the invention, the signal laser seed source 1 can be a solid-state laser, a fiber laser, a semiconductor laser, etc., as long as it can generate single-mode laser of that wavelength and couple it into the entire laser system for transmission and amplification.

[0056] In this embodiment of the invention, the signal laser seed source 1 and the first auxiliary laser source 2, the second auxiliary laser source 3... the Nth auxiliary laser source 4 can be in the form of an oscillator or an amplifier, as long as the injection power and wavelength requirements are met. This embodiment of the invention does not impose any restrictions on this.

[0057] In this embodiment of the invention, the first cladding pump source 6, the second cladding pump source 7, the third cladding pump source 8... the Nth cladding pump source 9 can be in the form of a semiconductor laser, a solid-state laser, or a fiber laser. It is only necessary to output the required pump laser wavelength and power and couple it into the cladding of the gain fiber 11. This embodiment of the invention does not limit this.

[0058] In this embodiment of the invention, the gain fiber 11 only needs to meet the amplification requirements of the laser seed source. This embodiment of the invention does not impose any restrictions on the fiber type, doping concentration, or size of the gain fiber 11.

[0059] Unless otherwise specified, the model numbers of the various devices in this embodiment of the invention are not limited, and any device that can perform the above functions is acceptable.

[0060] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of a preferred embodiment, and the sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A single-fiber 100 MW-class fiber laser based on auxiliary laser and cladding composite pumping, characterized in that, The laser includes: The center wavelength of the signal laser seed source output is λ S The signal laser, with the first auxiliary laser source, the second auxiliary laser source, ... the Nth auxiliary laser source having output center wavelengths of λ respectively. P1 , λ P2 , λ P3 …λ PN The lasers output from the auxiliary laser, signal laser seed source, first auxiliary laser source, second auxiliary laser source... Nth auxiliary laser source are coupled into the fiber core of the signal input port of the cladding pump light combiner through the laser signal combiner, and then enter the gain fiber. The output center wavelengths of the first cladding pump source, the second cladding pump source, the third cladding pump source, ..., the Nth cladding pump source are respectively λ PC1 , λ PC2 …λ PCN The cladding pump laser has a gradually increasing wavelength and is coupled into the cladding of the power amplifier stage fiber through the cladding pump beam combiner. The lasers output from the first auxiliary laser source, the second auxiliary laser source, ... the Nth auxiliary laser source and the signal laser seed source are sequentially amplified in the gain fiber. The amplification efficiency of the signal laser output from the signal laser seed source is suppressed in the front section of the gain fiber. As the cladding pump light power decreases, the first auxiliary laser source, the second auxiliary laser source, ... the Nth auxiliary laser source are gradually reabsorbed in the gain fiber. The signal laser is amplified in the rear section of the gain fiber, and a near-diffraction-limited laser output of 100 kilowatts is obtained after the output cap.

2. A single-fiber 100 MW-level fiber laser based on auxiliary laser and cladding composite pumping as described in claim 1, characterized in that, The center wavelength λ of the auxiliary laser source P1 , λ P2 , λ P3 …λ PN It should be located within the laser emission band of the rare-earth doped ions in the gain fiber, with the rare-earth doped ions at the center wavelength λ. P1 , λ P2 , λ P3 …λ PN The absorption and emission cross sections are higher than the center wavelength λ. S The signal laser.

3. A single-fiber 100 MW-level fiber laser based on auxiliary laser and cladding composite pumping as described in claim 1, characterized in that, The center wavelength is λ P1 , λ P2 …λ PN Assisted laser and center wavelength λ s The laser signal is amplified sequentially in the power amplifier stage, with a center wavelength of λ. P1 The smaller wavelength difference between the auxiliary laser and the cladding pump laser reduces the thermal load at the amplifier input. P2 …λ PN Assisted laser and center wavelength λ s When the signal laser is amplified sequentially, the quantum loss generated when each laser wavelength is amplified is reduced, and the thermal load is evenly distributed in the amplifier.

4. A single-fiber 100 MW-level fiber laser based on auxiliary laser and cladding composite pumping according to claim 1, characterized in that, The center wavelength is λ P1 , λ P2 …λ PN The auxiliary laser at the back of the amplifier is used to adjust the center wavelength λ. s The signal laser is used for core pumping to improve the threshold of signal laser mode instability effect.

5. A single-fiber 100 MW-level fiber laser based on auxiliary laser and cladding composite pumping according to claim 1, characterized in that, The center wavelength is λ P1 , λ P2 …λ PN The introduction of auxiliary lasers is used to suppress the center wavelength λ. s The gain of the signal laser in the amplifier front end is adjusted, the gain distribution of the signal laser in the power amplifier stage is controlled, and the effective nonlinear length of the signal laser is shortened.

6. A single-fiber 100 MW-level fiber laser based on auxiliary laser and cladding composite pumping according to claim 1, characterized in that, The output power of the signal laser seed source and the first auxiliary laser source, the second auxiliary laser source, ... the Nth auxiliary laser source can be adjusted individually to control the energy transfer process of the auxiliary laser and the signal laser in the subsequent power amplification stage.

7. A single-fiber 100 MW-level fiber laser based on auxiliary laser and cladding composite pumping according to claim 1, characterized in that, The first auxiliary laser source, the second auxiliary laser source, ... the Nth auxiliary laser source are solid-state lasers, fiber lasers, or semiconductor lasers; The first auxiliary laser source, the second auxiliary laser source, ... the Nth auxiliary laser source are single-longitudinal-mode lasers or multi-longitudinal-mode lasers; The first auxiliary laser source, the second auxiliary laser source, ... the Nth auxiliary laser source are single transverse mode lasers or higher-order transverse mode lasers.

8. A single-fiber 100 MW-level fiber laser based on auxiliary laser and cladding composite pumping according to claim 1, characterized in that, The first cladding pump source, the second cladding pump source, the third cladding pump source, ... the Nth cladding pump source can be in the form of a semiconductor laser, a solid-state laser, or a fiber laser.

9. A single-fiber 100 MW-level fiber laser based on auxiliary laser and cladding composite pumping according to claim 1, characterized in that, The signal laser seed source and auxiliary laser source are in the form of oscillators or amplifiers.

10. A single-fiber 100 MW-level fiber laser based on auxiliary laser and cladding composite pumping according to claim 1, characterized in that, The output cap is a laser transmission device used to reduce the power density at the laser output end face.

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