Method for suppressing stimulated raman scattering effect in fiber laser amplifier and evaluation method

Abstract

The application provides a method for inhibiting stimulated Raman scattering effect of a fiber laser amplifier and an evaluation method, wherein a new seed laser is added in the fiber laser amplifier to be optimized, two seed lasers output by the new seed laser and an original seed laser are coupled into one laser by a signal coupler, and the laser is injected into a gain fiber of the fiber laser amplifier to realize power amplification, wherein time domain stability of the laser output by the new seed laser is better than that of the laser output by the original seed laser; four-wave mixing effect of the two seed lasers in the power amplification process of a main amplification stage of the fiber laser amplifier is utilized to realize regulation of time domain and spectral characteristics of the whole injection seed laser in the power amplification process of the main amplification stage, effectively improve laser time domain stability or broaden laser spectral width, reduce effective Raman gain coefficient, and then inhibit stimulated Raman scattering effect and improve stimulated Raman scattering effect threshold of the fiber laser amplifier.

Description

Technical Field

[0001] This invention mainly relates to the field of fiber laser technology, and in particular to a method and evaluation method for suppressing stimulated Raman scattering effect in a fiber laser amplifier. Background Technology

[0002] In high-power fiber laser systems, the impact of nonlinear effects in the fiber becomes increasingly significant with the increase in output power, especially stimulated Raman scattering (SRS). SRS transfers most of the signal light energy to Raman light of the corresponding wavelength after the fiber laser system reaches its threshold power, thus limiting further increases in the output power of high-power fiber laser systems. Effectively suppressing SRS has become a key factor in further improving the power of high-power fiber laser systems.

[0003] Fiber laser amplifiers based on a master oscillator power amplification structure are currently the main method for achieving high-power fiber laser output. In fiber laser amplifiers based on this structure, Raman spectral components are mainly generated in the master amplification stage. Therefore, suppressing stimulated Raman scattering (SRS) in fiber laser amplifiers primarily revolves around the structural design of the master amplification stage. Common methods fall into two main categories: The first is to modify the structural design of the gain fiber. This method can increase the effective mode area of ​​the fiber, reduce the fiber length, reduce the power overlap factor between the Raman spectral components and the signal spectral components, or increase the loss coefficient of the Raman spectral components. The second is to introduce additional Raman spectral component filtering devices. This method can directly separate the Raman spectral components from the signal spectral components in the laser. However, both of these methods require additional components to match the new gain fiber and filtering devices. While suppressing SRS, this can easily lead to degradation of other performance characteristics of the fiber laser amplifier, such as beam quality, power conversion efficiency, and reliability.

[0004] Based on the existing problems and limitations, this paper proposes a method to effectively suppress stimulated Raman scattering in fiber laser amplifiers without changing the main amplification stage structure design. This method has important practical significance for further improving the power and performance of high-power fiber lasers. Summary of the Invention

[0005] To address the technical problems existing in the prior art, this invention proposes a method and evaluation method for suppressing stimulated Raman scattering effect in fiber laser amplifiers.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] On one hand, the present invention provides a method for suppressing stimulated Raman scattering in a fiber laser amplifier, comprising:

[0008] The fiber laser amplifier to be optimized is identified. The fiber laser amplifier to be optimized includes a primary seed laser for injecting seed laser into the fiber laser amplifier.

[0009] Optimization of a fiber laser amplifier involves adding a new seed laser to the amplifier. The two seed lasers output from the new and original seed lasers are coupled into a single laser stream via a signal coupler and injected into the gain fiber of the fiber laser amplifier for power amplification. The temporal stability of the laser output from the new seed laser is superior to that from the original seed laser. By utilizing the four-wave mixing effect of the two seed lasers during the power amplification process in the main amplification stage of the fiber laser amplifier, the temporal and spectral characteristics of the injected seed laser during the power amplification process in the main amplification stage can be controlled. This effectively improves the temporal stability of the laser or broadens the laser spectral width, reduces the effective Raman gain coefficient, and thus suppresses stimulated Raman scattering, thereby increasing the stimulated Raman scattering threshold of the fiber laser amplifier.

[0010] Furthermore, the type of fiber laser amplifier described in this invention is not limited, and it can be a forward-pumped fiber laser amplifier, a backward-pumped fiber laser amplifier, or a bidirectional pumped fiber laser amplifier.

[0011] Furthermore, the fiber laser amplifier described in this invention is a non-polarization-maintaining fiber laser amplifier or a polarization-maintaining fiber laser amplifier.

[0012] Furthermore, the types of lasers used in the original seed laser and the new seed laser of this invention are not limited, and the original seed laser and the new seed laser can use the same type of laser or different types of lasers. The optional laser types for the original seed laser and the new seed laser include different types such as fiber laser oscillators, superfluorescent fiber lasers, random fiber lasers, single-frequency fiber lasers, and phase-modulated single-frequency fiber lasers.

[0013] Furthermore, the power difference between the original seed laser and the new seed laser described in this invention is within 10%.

[0014] The doping distribution of the core of the gain fiber is not limited; it can be uniformly doped, partially uniformly doped, or non-uniformly doped. The gain dopant in the gain fiber is Yb. 3+ Er 3+ 、Nd 3+ Ho 3+ and Tm 3+ Any one or more rare earth ions.

[0015] On the other hand, an evaluation method is provided for the above-mentioned method of suppressing stimulated Raman scattering effect in fiber laser amplifiers, including:

[0016] The power P of the Raman laser in the output laser of the fiber laser amplifier to be optimized before adding a new seed laser is determined. R0 ;

[0017] Determine the power P of the Raman laser in the output laser of the fiber laser amplifier after adding a new seed laser and injecting additional new seed laser. R1 ;

[0018] Based on P R0 / P R1 To evaluate the ability of a fiber laser amplifier to suppress stimulated Raman scattering after the addition of a new seed laser, specifically, P R0 / P R1 The larger the value, the stronger the ability of the optimized fiber laser amplifier to suppress stimulated Raman scattering.

[0019] The above evaluation method provides a clear approach for optimizing the selection of new seed lasers to effectively suppress stimulated Raman scattering in fiber laser amplifiers.

[0020] Furthermore, based on the above evaluation method, a method for optimizing the seed laser in a fiber laser amplifier is provided, wherein among several candidate seed lasers, the one that makes P... R0 / P R1 The largest new seed laser was ultimately chosen as the new seed laser for the fiber laser amplifier.

[0021] The beneficial effects of this invention are as follows:

[0022] 1. Compared with existing methods for suppressing stimulated Raman scattering in fiber laser amplifiers, this invention does not require changes to the structural design of the main amplification stage in the fiber laser amplifier, and has good stability.

[0023] 2. This invention does not require additional design of gain fiber or fiber device; the required new seed laser can be directly designed using existing fiber seed lasers, making it simple to implement.

[0024] 3. This invention is versatile and can be widely applied to suppress stimulated Raman scattering in various types of fiber laser amplifiers.

[0025] In summary, this invention has significant application value in the field of high-power lasers, particularly in the system design and performance optimization of high-power fiber laser amplifiers. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of the fiber laser amplifier to be optimized in one embodiment;

[0028] Figure 2 This is a schematic diagram of the optimized fiber laser amplifier in one embodiment;

[0029] Figure 3 This is a typical spectral effect diagram of suppressing stimulated Raman scattering in one embodiment, where the horizontal axis is wavelength (nm) and the vertical axis is the spectral normalized intensity (dB) based on the total laser power.

[0030] Figure 4 This is a typical Raman light power ratio effect diagram for suppressing stimulated Raman scattering in one embodiment, where the horizontal axis is the output power (kW) and the vertical axis is the ratio of Raman light power to total laser power (dB).

[0031] Numbering on the map:

[0032] 1. Original seed laser; 2. New seed laser; 3. Signal coupler; 4. Pump source; 5. Pump signal combiner; 6. Gain fiber. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0034] Reference Figure 1 One embodiment provides a method for suppressing stimulated Raman scattering in a fiber laser amplifier, comprising:

[0035] The fiber laser amplifier to be optimized is identified. The fiber laser amplifier to be optimized includes a primary seed laser for injecting seed laser into the fiber laser amplifier.

[0036] Optimization of a fiber laser amplifier involves adding a new seed laser to the amplifier. The two seed lasers output from the new and original seed lasers are coupled into a single laser stream via a signal coupler and injected into the gain fiber of the fiber laser amplifier for power amplification. The temporal stability of the laser output from the new seed laser is superior to that from the original seed laser. By utilizing the four-wave mixing effect of the two seed lasers during the power amplification process in the main amplification stage of the fiber laser amplifier, the temporal and spectral characteristics of the injected seed laser during the power amplification process in the main amplification stage can be controlled. This effectively improves the temporal stability of the laser or broadens the laser spectral width, reduces the effective Raman gain coefficient, and thus suppresses stimulated Raman scattering, thereby increasing the stimulated Raman scattering threshold of the fiber laser amplifier.

[0037] Furthermore, this invention proposes a method to improve the ability to suppress stimulated Raman scattering (SRS) in fiber laser amplifiers by injecting an additional new seed laser. The key to improving the ability to suppress SRS depends on the temporal stability of the original seed laser and the new seed laser, and the wavelength interval between them. Specifically, the temporal stability of the new seed laser is superior to that of the original seed laser. Preferably, the center wavelengths of the original seed laser and the new seed laser can be the same or different. If the center wavelengths of the original seed laser and the new seed laser are different, then the difference between their center wavelengths must be less than 5 nm.

[0038] In one embodiment, an evaluation method is provided for the above-described method of suppressing stimulated Raman scattering effect in a fiber laser amplifier, comprising:

[0039] The power P of the Raman laser in the output laser of the fiber laser amplifier to be optimized before adding a new seed laser is determined. R0 ;

[0040] Determine the power P of the Raman laser in the output laser of the fiber laser amplifier after adding a new seed laser and injecting additional new seed laser. R1 ;

[0041] Based on P R0 / P R1 To evaluate the ability of a fiber laser amplifier to suppress stimulated Raman scattering after the addition of a new seed laser, specifically, P R0 / P R1 The larger the value, the stronger the ability of the optimized fiber laser amplifier to suppress stimulated Raman scattering.

[0042] The power of the Raman laser in the output laser of a fiber laser amplifier can be calculated using the following equation and the corresponding structural parameters of the fiber laser amplifier:

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050] A s =A1+A2 (8)

[0051] P R =<|A R | 2 > (9)

[0052] Where ± represents the forward and reverse propagation along the gain fiber, respectively, and P p Γ represents the pump laser power, z represents the position along the gain fiber direction, and Γ represents the position along the gain fiber direction. p The power overlap factor of the pump laser is represented by N1 and N2, which represent the total number of rare earth ions in the ground and excited states of the gain fiber, respectively. N0 = N1 + N2 is the concentration of rare earth doped ions in the gain fiber. σ p a and σ p e α represents the absorption and emission cross-sections of rare-earth doped rare-earth ions in the gain fiber at the pump laser wavelength, respectively. p This represents the loss factor of the pump laser in the gain fiber; g represents the envelope of the signal laser field in the frequency domain. s The signal laser gain coefficient, α, in the gain fiber s Let F{} represent the loss coefficient of the signal laser in the gain fiber, F{} represent the Fourier transform operation, and R... s β represents the Raman response parameter of the signal laser. 2,s γ represents the second-order dispersion coefficient at the signal laser wavelength in the gain fiber, where ω is the angular frequency of the laser, and γ is the second-order dispersion coefficient. s A represents the nonlinear Kerr coefficient at the signal laser wavelength in the gain fiber. s f represents the envelope of the signal laser field in the time domain. R A represents the contribution of the delayed Raman response to the nonlinear polarizability. R This represents the envelope of the Raman laser field in the time domain; G represents the envelope of the Raman laser field in the frequency domain.R Raman laser gain coefficient, α in gain fiber R R represents the loss coefficient of Raman laser light in a gain fiber. R β represents the Raman response parameter of a Raman laser. 2,R γ represents the second-order dispersion coefficient at the Raman laser wavelength in the gain fiber. R Γ represents the nonlinear Kerr coefficient at the Raman laser wavelength in the gain fiber; s σ represents the power overlap factor of the laser signal. s a and σ s e These represent the absorption and emission cross sections of rare-earth doped rare-earth ions in the gain fiber at the signal laser wavelength, respectively; Γ R σ represents the power overlap factor of the pump laser. R a and σ R e These represent the absorption and emission cross sections of rare-earth doped rare-earth ions in the gain fiber at the Raman laser wavelength, respectively; h R Let ω be the Raman response function in the gain fiber. s and ω R These represent the angular frequencies of the signal laser and the Raman laser, respectively. * denotes convolution operation, * denotes complex conjugation operation; A1 and A2 represent the time-domain envelopes of the original seed laser and the new seed laser, respectively; P R This represents the power of the Raman laser, and <> indicates averaging.

[0053] This invention proposes a method to suppress stimulated Raman scattering (SRS) in fiber laser amplifiers by injecting additional new seed lasers. The ability of the proposed method to suppress SRS depends on the temporal stability of the original seed laser and the new seed laser, as well as the wavelength spacing between the original seed laser and the new seed laser.

[0054] The Raman laser power P in the output laser of the fiber amplifier before the new seed laser is injected can be calculated using equations (1) to (9) and the corresponding fiber laser amplifier structural parameters. R0 Raman laser power P in the output laser of the fiber amplifier after additional injection of new seed laser R1 The ratio P between the two R0 / P R1 The larger the value, the stronger the ability to suppress stimulated Raman scattering, providing a clear method for optimizing the selection of new seed lasers to effectively suppress stimulated Raman scattering in fiber laser amplifiers.

[0055] The above evaluation method provides a clear approach for optimizing the selection of new seed lasers to effectively suppress stimulated Raman scattering in fiber laser amplifiers.

[0056] The method provided by this invention is universal and can be widely applied to suppress stimulated Raman scattering in various types of fiber laser amplifiers. In terms of pumping method, the fiber laser amplifier described in this invention can be a forward-pumped fiber laser amplifier, a backward-pumped fiber laser amplifier, or a bidirectional pumped fiber laser amplifier. In terms of pump source, the fiber laser amplifier described in this invention can be a semiconductor-pumped fiber laser amplifier or a co-band pumped fiber laser amplifier. In terms of polarization characteristics, the fiber laser amplifier described in this invention can be a non-polarization-maintaining fiber laser amplifier or a polarization-maintaining fiber laser amplifier. In terms of seed laser type, the original seed laser in the fiber laser amplifier described in this invention can be different types of fiber seed lasers, such as fiber laser oscillators, superfluorescent fiber lasers, random fiber lasers, single-frequency fiber lasers, and phase-modulated single-frequency fiber lasers.

[0057] In one embodiment, based on the above evaluation method, a method for selecting the optimal seed laser in a fiber laser amplifier is provided, wherein among several candidate seed lasers, the one that makes P... R0 / P R1 The largest new seed laser was ultimately chosen as the new seed laser for the fiber laser amplifier.

[0058] As attached Figure 1 As shown in the figure, this embodiment provides a method for suppressing stimulated Raman scattering effect in a fiber laser amplifier.

[0059] Fiber laser amplifiers to be optimized, such as Figure 1 As shown, it includes a seed laser 1, a pump source 4, a pump signal combiner 5, and a gain fiber 6. When only the seed laser 1 is used, the corresponding fiber laser amplifier is in its original state without suppression of stimulated Raman scattering.

[0060] right Figure 1 The fiber laser amplifier shown is optimized by adding a new seed laser 2. The two seed lasers output from the new seed laser 2 and the original seed laser 1 are coupled into a single laser beam via a signal coupler 3. This beam is then injected into the gain fiber 6 along with the pump light 4 via a pump signal combiner 5 to achieve power amplification. When both the original seed laser 1 and the new seed laser 2 are used simultaneously, the corresponding fiber laser amplifier is in an optimized state that suppresses stimulated Raman scattering.

[0061] In this application example, without loss of generality, the original seed laser 1 is a phase-modulated single-frequency fiber laser with a working wavelength of 1064.5nm and a power of 30W. The new seed laser 2 is a phase-modulated single-frequency fiber laser with a working wavelength of 1064nm and a power of 30W. The fiber laser amplifier uses 976nm pump light for pumping, and the pump light power is adjustable. The gain fiber 6 is ytterbium-doped fiber with a fiber length of 16m. When the original seed laser 1 and the original seed laser 2 are used simultaneously, in order to keep the total power of the injected seed lasers constant, their power is set to 15W.

[0062] The output spectral characteristics of the fiber laser amplifier were measured under two conditions: using only the original seed laser 1 and using an additional new seed laser, when the output power of the fiber laser amplifier was 2.2kW. (See attached figure.) Figure 2 As shown. (From the appendix) Figure 3 The results show that, under the same output power, using two seed lasers simultaneously effectively reduces the Raman spectral components in the output laser, thus suppressing the stimulated Raman scattering effect.

[0063] The changes in the proportion of Raman light power in the output laser of the fiber laser amplifier under two conditions—using only the original seed laser 1 and using an additional new seed laser—are shown in the attached figure. Figure 4 As shown. (From the appendix) Figure 3 The results show that, under the same output power, when two seed lasers are used simultaneously, the proportion of Raman light power in the output laser decreases significantly with the increase of output power, indicating that the stimulated Raman scattering effect in the fiber laser amplifier is effectively suppressed.

[0064] Matters not covered in this invention are common knowledge.

[0065] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0066] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

[0067] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for suppressing stimulated Raman scattering in a fiber laser amplifier, characterized in that, include: The fiber laser amplifier to be optimized is identified. The fiber laser amplifier to be optimized includes a primary seed laser for injecting seed laser into the fiber laser amplifier. This method optimizes a fiber laser amplifier without altering the structural design of the main amplification stage or requiring additional gain fiber or fiber optic devices. Specifically, it adds a new seed laser to the amplifier. The two seed lasers output from the new and original seed lasers are coupled together via a signal coupler and injected into the gain fiber of the fiber laser amplifier for power amplification. The temporal stability of the output laser from the new seed laser is superior to that from the original seed laser. By utilizing the four-wave mixing effect of the two seed lasers during the power amplification process in the main amplification stage, the temporal and spectral characteristics of the injected seed laser during the power amplification process can be controlled. This effectively improves the temporal stability of the laser or broadens the laser spectral width, reduces the effective Raman gain coefficient, and thus suppresses stimulated Raman scattering, thereby increasing the stimulated Raman scattering threshold of the fiber laser amplifier.

2. The method for suppressing stimulated Raman scattering in a fiber laser amplifier according to claim 1, characterized in that, The fiber laser amplifier is a forward-pumped fiber laser amplifier, a backward-pumped fiber laser amplifier, or a bidirectional pumped fiber laser amplifier.

3. The method for suppressing stimulated Raman scattering in a fiber laser amplifier according to claim 1, characterized in that, The fiber laser amplifier is either a non-polarization-maintaining fiber laser amplifier or a polarization-maintaining fiber laser amplifier.

4. The method for suppressing stimulated Raman scattering in a fiber laser amplifier according to claim 1, characterized in that, The original seed laser and the new seed laser may use the same or different types of lasers.

5. The method for suppressing stimulated Raman scattering in a fiber laser amplifier according to claim 4, characterized in that, The original seed laser and the new seed laser are fiber laser oscillators, superfluorescent fiber lasers, random fiber lasers, single-frequency fiber lasers, or phase-modulated single-frequency fiber lasers.

6. The method for suppressing stimulated Raman scattering effect in a fiber laser amplifier according to any one of claims 1 to 5, characterized in that, The original seed laser and the new seed laser have the same center wavelength.

7. The method for suppressing stimulated Raman scattering effect in a fiber laser amplifier according to any one of claims 1 to 5, characterized in that, The original seed laser and the new seed laser have different center wavelengths, and the difference between the center wavelengths of the original seed laser and the new seed laser is less than 5 nm.

8. The method for suppressing stimulated Raman scattering in a fiber laser amplifier according to any one of claims 1 to 5, characterized in that, The power difference between the original seed laser and the new seed laser is within 10%.

9. An evaluation method for the method of suppressing stimulated Raman scattering effect in a fiber laser amplifier as described in claim 1, characterized in that: include: The power of the Raman laser in the output laser of the fiber laser amplifier to be optimized before adding a new seed laser. P R0 ; Determine the power of the Raman laser in the output laser of the fiber laser amplifier after adding a new seed laser and injecting additional new seed laser. P R1 ; P R0 / P R1 The larger the value, the stronger the ability of the optimized fiber laser amplifier to suppress stimulated Raman scattering. The power of the Raman laser in the output laser of the fiber laser amplifier is calculated using the following equation and the corresponding structural parameters of the fiber laser amplifier: (1) (2) (3) (4) (5) (6) (7) (8) (9) Where ± represents the forward and reverse propagation along the gain fiber, respectively. P p Indicates the pump laser power. z Indicates the position along the direction of the gain fiber. Γ p The power overlap factor represents the power of the pump laser. N 1 and N 2 represents the total number of rare earth ions in the ground and excited states in the gain fiber, respectively. N 0= N 1+ N 2 represents the concentration of rare earth ions doped in the gain fiber. σ p a and σ p e These represent the absorption and emission cross sections of rare-earth doped ions in the gain fiber at the pump laser wavelength, respectively. α p This represents the loss factor of the pump laser in the gain fiber; Ã s This represents the envelope of the signal laser light field in the frequency domain. g s Signal laser gain coefficient in gain fiber α s This represents the loss factor of the signal laser in the gain fiber. F {} represents the Fourier transform operation. R s The Raman response parameters of the signal laser are represented. β 2,s This represents the second-order dispersion coefficient at the signal laser wavelength in the gain fiber. ω The angular frequency of the laser. γ s This represents the nonlinear Kerr coefficient at the signal laser wavelength in the gain fiber. A s This represents the envelope of the signal laser light field in the time domain. f R This represents the contribution of the delayed Raman response to the nonlinear polarizability. A R This represents the envelope of the Raman laser field in the time domain; Ã R This represents the envelope of the Raman laser light field in the frequency domain. g R Raman laser gain coefficient in gain fiber α R This represents the loss coefficient of the Raman laser in the gain fiber. R R This represents the Raman response parameters of a Raman laser. β 2,R This represents the second-order dispersion coefficient at the Raman laser wavelength in the gain fiber. γ R This represents the nonlinear Kerr coefficient at the Raman laser wavelength in the gain fiber; Γ s The power overlap factor of the laser signal is represented. σ s a and σ s e These represent the absorption and emission cross sections of the rare-earth doped ions in the gain fiber at the signal laser wavelength, respectively. Γ R The power overlap factor represents the power of the pump laser. σ R a and σ R e These represent the absorption and emission cross sections of rare-earth doped rare-earth ions in the gain fiber at the Raman laser wavelength, respectively. h R This refers to the Raman response function in a gain fiber. ω s and ω R These represent the angular frequencies of the signal laser and the Raman laser, respectively. The symbol represents convolution, and * represents complex conjugate. A 1 and A 2 represents the time-domain envelopes of the original seed laser and the new seed laser, respectively; P R This represents the power of the Raman laser, and <> indicates averaging.

10. A preferred method for a new seed laser in a fiber laser amplifier based on the evaluation method of claim 9, characterized in that, Among several candidate new seed lasers, the one chosen is... P R0 / P R1 The largest new seed laser was ultimately chosen as the new seed laser for the fiber laser amplifier.

Images