A resonant-pumped solid-state laser system and a multi-parameter collaborative optimization method thereof

Abstract

The application relates to the technical field of solid-state lasers. The application provides a resonant-pumped solid-state laser system and a multi-parameter collaborative optimization method thereof. The system comprises a pumping source, a beam shaping unit, a resonant cavity, and a gain medium located in the resonant cavity. The gain medium has a multi-parameter collaborative optimization architecture, and the optimization parameters include the length and the doping concentration of the gain medium. The beam shaping unit determines the specific beam waist position of the pumping light according to an absorption-weighted minimization strategy, so that the effective pumping spot radius of the pumping light in the gain medium is minimized. The resonant-pumped solid-state laser system is optimized through multi-parameter collaboration, so that the local gain in the full-length range of the gain medium is always higher than the absorption loss, and the gain dead zone is eliminated.

Description

Technical Field

[0001] This application relates to the field of solid-state laser technology, and more specifically, to a resonant-pumped solid-state laser system and its multi-parameter collaborative optimization method. Background Technology

[0002] In existing technologies, researchers generally prefer to use shorter (usually) lengths. And the doping concentration is high (usually) The gain medium is the 790 nm pumping medium. This design bias mainly stems from the path dependence of traditional 790 nm pumping technology. In the 790 nm pumping scheme, a high doping concentration is required to induce a significant cross-relaxation (CR) effect in order to achieve a quantum efficiency multiplication of "pumping one photon to generate two excited-state ions".

[0003] However, upon transitioning to 1.7 Following resonant pumping, the researchers continued with the high-doping approach. For example, they used crystals only 4 mm long. In fact, resonant pumping involves direct level transitions and does not require cross-relaxation. On the contrary, excessively high doping concentrations can exacerbate the harmful energy transfer upconversion (ETU) effect, leading to increased thermal load.

[0004] Furthermore, in existing resonant-pumped solid-state lasers, increasing the pump power is typically necessary to improve output power. This carries the risk of severe thermal lensing and physical damage due to excessive thermal load concentration at high power pumping on short crystals. Additionally, there is the problem of reduced pump intensity at the crystal's output end due to the Gaussian diffraction divergence characteristics of the pump light, caused by simply increasing the crystal length. Moreover, when the pump rate falls below the inversion distribution threshold, the crystal's output end becomes a strong reabsorber (i.e., a "gain dead zone"), leading to a significant decrease in slope efficiency.

[0005] Therefore, it is necessary to provide a resonant pumped solid-state laser system and its multi-parameter collaborative optimization method to solve one of the above-mentioned technical problems. Summary of the Invention

[0006] The purpose of this application is to provide a resonant-pumped solid-state laser system that can solve at least one of the technical problems mentioned above. The specific solution is as follows: According to a specific embodiment of this application, this application provides a resonant-pumped solid-state laser system, comprising: A pump source is used to emit pump light of a specified wavelength; a beam shaping unit includes a first lens and a second lens, which is used to collimate and focus the pump light; a resonant cavity includes a plane mirror and a curved mirror; a gain medium is located in the resonant cavity, which has a multi-parameter collaborative optimization architecture, and the optimization parameters include the length and doping concentration of the gain medium; wherein, the beam shaping unit determines the specific beam waist position of the pump light by minimizing the effective pump spot radius of the pump light in the gain medium according to an absorption weighted minimization strategy.

[0007] According to a specific embodiment of this application, this application provides a multi-parameter collaborative optimization method for a resonant-pumped solid-state laser system, which is implemented using the resonant-pumped solid-state laser system described in this application. The multi-parameter collaborative optimization method includes: determining the initial range of the length and doping concentration of the gain medium; establishing a target optimization function based on the effective pump spot radius to determine the specific beam waist position of the pump light; performing physical constraint verification on the determined specific beam waist position of the pump light; and calculating the thermal load temperature in the gain medium based on the effective pump spot radius determined by the optimized specific beam waist position, so as to dynamically adjust the length and doping concentration of the gain medium to obtain the optimal parameter combination.

[0008] The above-described solutions in the embodiments of this application have at least the following beneficial effects: This application optimizes the resonant pumped solid-state laser system by optimizing the structure of the beam shaping unit, the length of the gain medium, the doping concentration, and the physical constraint of minimizing the effective pump spot radius to determine the specific beam waist position of the pump light. This multi-parameter collaborative optimization eliminates the gain death region and improves the slope efficiency of the system by more than 15% without increasing the total pump power. Attached Figure Description

[0009] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings: Figure 1 This is a schematic diagram of the overall structure of the resonant-pumped solid-state laser system provided in the embodiments of this application; Figure 2 A schematic diagram of parameter curves showing the process by which the optimal length and optimal doping concentration of the gain medium are dynamically adjusted as the pump power increases in the resonant pumped solid-state laser system provided in this application embodiment. Figure 3A schematic diagram of parameter curves for optimizing the specific beam waist position of the pump light as the pump power increases in the resonant pumped solid-state laser system provided in this application embodiment; Figure 4 A schematic diagram showing the axial position of the pump light entering the gain medium in the existing method is shown; Figure 5 A schematic diagram showing the axial position of the pump light entering the gain medium in a resonant pumped solid-state laser system provided in this application embodiment; Figure 6 A flowchart illustrating the multi-parameter collaborative optimization method for a resonant-pumped solid-state laser system provided in this application embodiment; Figure 7 A comparison diagram showing the effect verification of the multi-parameter collaborative optimization method for the resonant pumped solid-state laser system provided in the embodiments of this application with existing methods.

[0010] Explanation of reference numerals in the attached figures: 10: Pump source; 20: Beam shaping unit; 30: Resonant cavity; 40: Gain medium; f1: First lens; f2: Second lens; IM: Plane mirror; OC: Curved mirror. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0012] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the article or device that includes said element.

[0013] In view of the above problems, this application provides a resonant-pumped solid-state laser system and its multi-parameter collaborative optimization method. This application utilizes structural optimization of the beam shaping unit, optimization of the length of the gain medium, optimization of the doping concentration, and physical constraints based on minimizing the effective pump spot radius to determine the specific beam waist position of the pump light. Multi-parameter collaborative optimization further optimizes the resonant-pumped solid-state laser system, eliminates the gain death region, and improves the slope efficiency of the system by more than 15% without increasing the total pump power.

[0014] The following is in conjunction with the appendix Figures 1 to 5 Detailed description of optional embodiments of this application.

[0015] like Figure 1 As shown, according to a specific embodiment of this application, this application provides a resonant-pumped solid-state laser system. The resonant-pumped solid-state laser system includes a pump source 10, a beam shaping unit 20, a resonant cavity 30, and a gain medium 40 located within the resonant cavity 30.

[0016] Specifically, the pump source is used to emit pump light of a specified wavelength, where the specified wavelength refers to a wavelength locked in the 1.7 μm band, which can, for example, enable thulium ions to transition from their ground state... 3 to excited state 3 The direct transition. A gain medium 40 is provided inside the resonant cavity 30. The gain medium 40 has a multi-parameter cooperative optimization architecture, which can obtain a high-efficiency output beam.

[0017] Alternatively, the gain medium may employ a long-size, low-doped architecture.

[0018] Specifically, the gain medium 40 is, for example, Tm:YAP. The length of the gain medium (e.g., represented by L) is the length of the gain medium after optimization based on the principle of high power heat load distribution, and the value is 20mm to 60mm. By setting the above length range, the high power heat load can be distributed to a larger volume, which can suppress the thermal lensing effect.

[0019] Optionally, the doping concentration (e.g., represented by C) is 0.5 at.% to 2 at.%. With concentration compensation based on the set length range of the gain medium, the axial absorption coefficient can be reduced, ensuring that the pump light energy penetrates the entire length of the long crystal and avoiding excessive heat deposition at the front end.

[0020] Specifically, the beam shaping unit 20 is located between the pump source 10 and the gain medium 40. The beam shaping unit 20 includes a first lens f1 and a second lens f2. The first lens is used to collimate the pump light emitted by the pump source 10, and the second lens f2 is used to focus the pump light emitted by the pump source 10, so that the pump light emitted by the pump source 10 can be precisely shaped.

[0021] The beam shaping unit 20 minimizes the effective pump spot radius of the pump light within the gain medium 40 according to an absorption-weighted minimization strategy. The specific beam waist position of the pump light is determined based on the physical constraint of minimizing the effective pump spot radius.

[0022] In this example, a specific beam waist position of the pump light is disposed within the incident light region of the gain medium, and the distance between the position point corresponding to the specific beam waist position and the starting point of the incident light region of the gain medium (e.g., using...) (represented) less than a specific length (e.g., using) (where L represents the length of the optimized gain medium), which satisfies the following expression: The beam waist radius (also known as the effective pump spot radius) is the position of the beam waist formed along the axial direction of the pump beam. The diameter of the wire waist is 200 μm, and the wire waist diameter is 400 μm, which is 2. .

[0023] Optionally, the length of the optimized gain medium The diameter is 20mm to 60mm.

[0024] exist Figure 1 In the example, the resonant cavity 30 includes a cavity located on the first side (i.e., Figure 1 The plane mirror IM on the left side of the middle, located on the second side (i.e. Figure 1 A resonant cavity is formed between the curved mirror OC (on the right side of the image) and the plane mirror IM. The pump light, shaped by the curved mirror, passes through the plane mirror IM and enters the resonant cavity. The plane mirror IM is highly transparent to the pump light but highly reflective of, for example, 2μm laser light. The curved mirror OC, i.e., the output coupler, allows the first portion of the 2μm laser light to be projected and output, while the rest is reflected back into the resonant cavity 30. A gain medium 40 is disposed within the resonant cavity 30.

[0025] To achieve a gain-free dead zone, the length of the gain medium 40 was optimized so that the pump light forms a specified length when entering the resonant cavity 30 (e.g., using...). (represented), and the specified length satisfies the following expression: .in, This indicates that the pump light forms a specified length when it enters the resonant cavity 30. This indicates the length of the optimized gain medium.

[0026] Based on the change in pump power, the size of the light spot formed by the pump is controlled, and the length and doping concentration of the gain medium are dynamically adjusted.

[0027] Regarding the length of the gain medium, this application employs a multi-parameter collaborative determination process under pump power conditions ranging from 10W to 100W. Particularly in extreme environments with pump power ranging from 80W to 100W, the pump spot size is controlled in accordance with power variations, and a multi-parameter collaborative determination process is performed in conjunction with the length and concentration configuration of the gain medium (see details). Figure 2 and Figure 3 This allows for the elimination of reabsorption loss at the output of the gain medium without thermal damage, by satisfying the physical constraint of a specified length formed when the pump light enters the resonant cavity.

[0028] Figure 2 The diagram illustrates the variation of the optimal crystal length and optimal doping concentration of the gain medium (i.e., the crystal) as the pump power increases (10W–100W). In the first power stage (10W–20W), due to the relatively low heat load, a high doping concentration (approximately 4 at.%) and a short crystal (approximately 10mm–20mm) are preferred to achieve high gain output within a compact crystal size. In the second power stage (20W–70W), the optimal doping concentration remains relatively stable, and the concentration curve enters a plateau region. In the third power stage (80W–100W), to cope with the significantly increased heat load, the optimal doping concentration decreases to 0.5 at.%, while the optimal crystal length gradually increases to 80mm.

[0029] Figure 3 This paper illustrates the optimization process of the waist radius of the pump beam (i.e., a specific waist position) as pump power increases, as well as the dynamic adjustment process of the optimal crystal length and optimal doping concentration of the gain medium (i.e., the crystal). After the power exceeds 40W, the waist radius at the specific waist position, i.e., the effective pump spot radius, rapidly increases from 120μm to nearly 300μm with increasing power. In the 20W–70W range, due to limited increases in crystal length, the heat generation intensity per unit area is preferentially reduced by increasing the spot area. When the power reaches 90W–100W, the waist radius at the specific waist position shows a slight pullback; the crystal length has increased to 80mm, providing sufficient axial heat dissipation space, allowing for a suitable reduction in spot size to improve pump intensity and slope efficiency, thereby obtaining the optimal specific waist position, i.e., the optimal pump beam.

[0030] Using existing dynamic models, the absorption of the pump beam at the current pump beam quality in crystals of various concentrations and lengths is directly calculated to determine the doping concentration and length of the gain medium.

[0031] It should be noted that regarding the physical relationship between beam quality and various doping concentrations, lengths, etc., beam quality (e.g.) The doping factor directly determines the diffraction and divergence characteristics of the pump beam within the gain medium (i.e., the crystal) (i.e., whether the pump beam is "long and thin" or "short and thick"), which fundamentally determines the spatial power density distribution within the crystal. Beam quality and thermal load (corresponding to the coordination of concentration and length) are crucial; the absorption of the pump beam within the crystal follows an exponential decay, with most energy deposited at the incident end. If the beam quality is good and the focusing is minimal, the local power density at the front end will be extremely high. The kinetic model is based on this physical reality. To prevent thermal damage at the incident end under high power, the crystal doping concentration must be reduced (weakening the absorptivity per unit volume, shifting the thermal load to subsequent stages), while simultaneously increasing the crystal length significantly (to compensate for the decrease in overall absorptivity due to low doping concentration and to provide greater axial heat dissipation space). Figure 2 In the third power stage (i.e., the high power stage), the concentration drops sharply and the length increases significantly.

[0032] Beam quality and gain dead zone (corresponding) Figure 3 Beam waist radius adjustment at a specific beam waist position: Due to the natural divergence of the pump beam, if the crystal is too long or the beam quality is poor (divergence is too fast), the pump intensity at the output end of the gain medium (i.e., the crystal) will be lower than the inversion distribution threshold, forming a "reabsorption dead zone" (i.e., Figure 4 (The region is represented by P). Therefore, the spot size must be strictly matched with the crystal length.

[0033] The parameter co-optimization process includes the following steps.

[0034] Step S201: Input boundary parameters.

[0035] Specifically, the beam quality parameters of the current pump source, the preset maximum pump power, and the thermal damage safety threshold are input into the dynamic model.

[0036] Step S202: First dynamic optimization process.

[0037] Reference Figure 2 and Figure 3 Within the power range of 10W to 70W, calculations show that the heat generation at the input end has not reached the physical limit. At this point, the kinetic model output prioritizes maintaining a high doping concentration (approximately 2.2 at.% to 4 at.%) and a shorter crystal, and appropriately adjusts the beam waist radius at a specific beam waist position, i.e., the effective pump spot radius (e.g., 120 μm to 230 μm), in exchange for the shortest resonant cavity and the highest small-signal gain.

[0038] Step S203: Second dynamic optimization process.

[0039] As the power continues to increase (80W–100W), the calculated thermal load at the input optical terminal is about to exceed the safety threshold. At this point, the kinetic model triggers a low-level constraint mechanism, forcibly reducing the doping concentration to 0.5 at.%, and simultaneously increasing the crystal length to 80mm (see [reference]). Figure 2 ).

[0040] Step S204: Beam shaping coordination process.

[0041] After determining the long crystal and low doping concentration, a judgment was made based on the beam divergence law (Rayleigh length constraint). If the beam spot is too small, the focal point will be extremely hot; if the beam spot is too large, there will be no gain dead zone at the output end. Ultimately, it was calculated that at a power of 80W, the beam waist radius at a specific position needs to be increased to 300μm to distribute the heat, while at a power of 90W–100W, it is finely adjusted back to 230μm to ensure the pump threshold at the output end of the long crystal (see [reference]). Figure 3 ).

[0042] It should be noted that the doping concentration and the length of the gain medium are not independent variables, but rather the globally optimal solution obtained by the kinetic model under two contradictory physical constraints: "preventing thermal damage at the front end (requiring low concentration and large spot size)" and "eliminating the gain dead zone at the light output end (requiring Rayleigh length matching the crystal length and high pump intensity)".

[0043] from Figure 2 and Figure 3 As can be seen from this, the length of the optimized gain medium Preferably, the diameter is greater than 30 mm and less than 60 mm.

[0044] Furthermore, a cooling device (not shown in the figure) is provided on the outside of the gain medium 40, for example, using cooling water, the temperature of which is... The gain medium 40 is placed in a cooling device to dissipate the heat generated during high-power operation.

[0045] Figure 4 A schematic diagram showing the axial position of the pump light entering the gain medium (i.e., the crystal) in the existing method is shown. Figure 4 The horizontal axis in the diagram represents the horizontal direction, i.e., the axial position of the crystal, and is represented by Z. Figure 4 The vertical axis in the figure represents the vertical direction, i.e., the radial position, and is represented by R. Figure 5 This application provides a schematic diagram of the axial position of the pump light entering the gain medium (i.e., the crystal). Figure 5 The horizontal axis in the diagram represents the horizontal direction, i.e., the axial position of the crystal, and is represented by Z. Figure 5 The vertical axis in the graph represents the vertical direction, i.e., the radial position, denoted by R. From Figure 4 and Figure 5As can be seen from the existing methods, the pump light diverges too quickly, resulting in extremely low energy density and forming a "reabsorption dead zone," i.e., the dead zone P of the gain medium. However, this application, through beam shaping unit 20 and by positioning a specific beam waist position of the pump light in the incident region of the gain medium, allows the pump light to enter the gain medium 40 (i.e., the crystal) at a specific beam waist position and a specified length. This demonstrates that the pump light remains collimated and penetrates the entire gain medium (i.e., the crystal), effectively eliminating the dead zone of the gain medium and enabling high-efficiency laser beam output.

[0046] By utilizing a combination of the first and second lenses in the beam shaping unit, the pump light is directed into the gain medium 40 (i.e., the crystal) at a specific beam waist position and a designated length. This precise spatial matching achieves a gain dead zone-free state, effectively solving the heat dissipation problem (for long crystals) and the reabsorption loss problem.

[0047] It should be noted that the above is only an optional example and should not be construed as a limitation of this application.

[0048] Compared with existing technologies, this application optimizes the resonant pumped solid-state laser system by optimizing the structure of the beam shaping unit, the length of the gain medium, the doping concentration, and the physical constraint of minimizing the effective pump spot radius to determine the specific beam waist position of the pump light. This multi-parameter collaborative optimization ensures that the local gain of the gain medium is always higher than the absorption loss throughout the entire length of the gain medium, eliminating the gain death region. Without increasing the total pump power, the slope efficiency of the system in this application is improved by more than 15%.

[0049] Furthermore, by eliminating the gain death region, a higher beam quality and brighter output beam were obtained; the thermal management advantages of low-doped crystals were fully utilized, reducing the risk of thermal damage.

[0050] Below, we will refer to Figure 1 , Figure 6 and Figure 7 Using a beam generation example, the multi-parameter collaborative optimization method of this application will be explained in detail, which is implemented using a resonant-pumped solid-state laser system. Specifically, it includes the following steps.

[0051] First, in step S101, the length of the gain medium and the initial range of the doping concentration are determined.

[0052] Specifically, the physical limiting parameters of the pump source 10 are obtained, including the maximum injection power, the pump beam quality coefficient, and the pump wavelength. The maximum injection power is, for example, 100W. The pump wavelength is, for example, [missing information]. Wavelength of the band.

[0053] Pump source 10 emits pump light of a specified wavelength, where the specified wavelength refers to the wavelength locked in the 1.7μm band.

[0054] Furthermore, an initial range for the length of the gain medium 40 is determined, for example, from 20 mm to 60 mm. The initial range for the doping concentration is from 0.5 at.% to 4 at.%.

[0055] It should be noted that the above is only an optional example and should not be construed as a limitation of this application.

[0056] Next, in step S102, a target optimization function based on the effective pump spot radius is established to determine the specific beam waist position of the pump light.

[0057] To resolve the contradiction between the axial exponential attenuation and diffraction divergence of the pump light in the gain medium 40, the beam shaping unit 20 employs an absorption-weighted minimization strategy to minimize the effective pump spot radius within the gain medium 40. The effective pump spot radius is a comprehensive indicator that combines the propagation characteristics of the Gaussian beam with the absorption characteristics of the crystal.

[0058] The effective pump spot radius of the pump light within the gain medium 40 is expressed by the following expression: , in, This represents the effective pump spot radius of the pump light within the gain medium; This indicates the length of the optimized gain medium. The pump light absorption coefficient is represented by z, which represents the position coordinate of the pump light along the axial direction (direction of light propagation) Z inside the gain medium, i.e., the length of the pump light along the axial direction (direction of light propagation) inside the gain medium. This represents the function representing the variation of the pump spot along the axial direction. ,in, The effective pump spot radius of the pump light within the gain medium. This indicates the focusing position of the pump light, that is, the beam waist formed by the pump light along the axial direction. The specified length, i.e. the Rayleigh length of the pump beam, is formed when the pump light enters the resonant cavity 30.

[0059] It should be noted that in this application, the starting point is the intersection of the incident end face of the gain medium (crystal) (i.e., the end face where the pump beam just passes through the left coating and enters the crystal) and the light propagation direction (i.e., axis Z). The ending point is the emitting end face of the gain medium (crystal) (because L is the length of the optimized gain medium), meaning the length of the pump beam along the axial direction (propagation direction) inside the gain medium is equal to the total axial length. The region formed by moving a certain distance from the starting point along the emitting end face along the light propagation direction is the incident end region. The variable represents the real-time axial depth of the pump beam from the incident end face when it propagates along the light propagation direction (i.e., axis Z) inside the gain medium (crystal). express.

[0060] The specific beam waist position of the pump light is determined based on the physical constraint of minimizing the effective pump spot radius. Specifically, by minimizing the effective pump spot radius, the optimal balance point (i.e., the specific beam waist position) is automatically found between the extremely high density at the beam waist position and the low density at the divergence position, so as to ensure that the region with the most concentrated energy (the region with strong absorption) obtains the specific beam waist position.

[0061] In this example, the specific beam waist position of the pump light is located in the incident region of the gain medium, and the effective pump spot radius formed by the pump light along the axial direction (using...) The diameter of the wire waist is 200 μm, and the wire waist diameter is 400 μm, which is 2. .

[0062] The exponential absorption characteristics of the pump light in the gain medium 40 ( The specific beam waist position of the pump light is no longer focused at the crystal center, but is disposed in the incident end region of the gain medium, and the distance between the position point corresponding to the specific beam waist position and the starting point of the incident end region of the gain medium (e.g., using...) (indicated) less than a specific length (e.g., using) (where L represents the length of the optimized gain medium), which satisfies the following expression: By aligning the highest power density (at the specific beam waist) with the strongest absorption region (i.e., the incident light region) through the aforementioned specific beam waist configuration, the average power density within the effective gain volume is maximized, which aligns with the absorption weighted minimization strategy.

[0063] It should be noted that the above is only an optional example and should not be construed as a limitation of this application.

[0064] Next, in step S103, the physical constraint verification of the determined specific beam waist position of the pump light is performed.

[0065] Based on Rayleigh length matching law, the length of the gain medium was optimized so that the specified length formed when the pump light enters the resonant cavity satisfies the physical constraint with the optimized length of the gain medium. This is expressed by the following expression. , in, This indicates the Rayleigh length of the pump beam when it enters the resonant cavity 30, representing the length of the pump beam formed. ,in, The effective pump spot radius of the pump light within the gain medium is given by n, which represents the refractive index of the gain medium (e.g., a Tm:YAP crystal, with a value of 1.94). This indicates the wavelength of the pump light, for example, the wavelength in the 1.7μm band. The beam quality factor represents the pump source and is used to measure the divergence of the actual beam relative to the ideal Gaussian beam; L represents the length of the optimized gain medium.

[0066] Specifically, the length of the optimized gain medium is greater than 30 mm and less than 60 mm.

[0067] It should be noted that the judgment is based on the beam divergence law (Rayleigh length constraint). If the beam spot is too small, the focal point will be extremely hot; if the beam spot is too large, there will be no gain dead zone at the output end. See [link to relevant documentation] for details. Figure 3 .

[0068] When the specific beam waist position of the pump light satisfies the physical constraints, it indicates that the pump intensity at the output end of the gain medium is higher than the inversion distribution threshold.

[0069] When the determined specific beam waist position of the pump beam does not meet the physical constraints, the beam waist radius of the pump beam is repeatedly increased automatically, and / or the length of the gain medium is adjusted, until the physical constraints are met, so that the specific beam waist position of the pump beam is located in the incident end region of the gain medium, and the gain dead region is eliminated.

[0070] It should be noted that the above is only an optional example and should not be construed as a limitation of this application.

[0071] Next, in step S104, the thermal load temperature in the gain medium is calculated based on the effective pump spot radius determined by the optimized specific beam waist position, so as to dynamically adjust the length and doping concentration of the gain medium to obtain the optimal parameter combination.

[0072] The thermal load temperature within the gain medium is calculated based on the effective pump spot radius determined by the optimized specific beam waist position.

[0073] If the calculated thermal load temperature within the gain medium exceeds the safety threshold, it will automatically trigger a reduction in doping concentration and a linear increase in length.

[0074] If the calculated thermal load temperature within the gain medium does not exceed the safety threshold, the final output will be the optimal combination of parameters that dynamically evolves with power. This optimal combination of parameters includes the optimal doping concentration of the gain medium, the optimal length, and the specific beam waist position of the pump light.

[0075] Based on the obtained optimal parameter combination, the laser beam generation process is executed.

[0076] Figure 7 A comparison diagram showing the effect verification of the multi-parameter collaborative optimization method for the resonant pumped solid-state laser system provided in the embodiments of this application with existing methods.

[0077] To verify the practical advantages of this application, a comparative simulation experiment of power amplification and beam quality tracking under high-power pump conditions was conducted. The pump power (… The x-axis (where x is the horizontal axis) is the independent variable, continuously increasing from 10W to 150W, comparing the output power (...). (left ordinate) and beam quality factor (M) 2 The right-hand vertical axis represents two core performance indicators. Combined with... Figure 7 The solid line containing the circle indicates that the method of this application has the following advantages compared with the prior art: it breaks through the thermal saturation limit, achieving a continuous increase in output power; it effectively suppresses thermal lens distortion, maintaining constant and high-quality beam quality across the entire power range. Figure 7 As shown by the dashed line containing the black square, a laser system using a conventional design (such as a fixed highly doped, short crystal) exhibits severe thermal saturation in its output power curve after reaching a pump power of approximately 80W, resulting in a significant decrease in slope efficiency. In contrast, as... Figure 7 As shown by the solid line containing the white triangle, after applying the multi-parameter collaborative optimization method of this application, the long crystal, low doping concentration, and increased pump spot size were automatically matched under high power, and the heat load was evenly distributed, so that the output power maintained excellent linear growth with the pump power. Even under the extreme pumping condition of 150W, no thermally induced power foldback occurred, significantly improving the upper limit of the system's power extraction. Figure 7 As shown by the dashed line containing the black triangle, in existing technologies, under high-power pumping, excessively concentrated heat deposition induces a severe thermal lensing effect, leading to a rapid deterioration of beam quality. 2 The beam quality factor spiked and spiraled out of control (greater than 5) in the later stages, reducing its application value and scope. In contrast, this application (containing the solid line of the white triangle) benefits from optimized Rayleigh length matching and beam spot control, completely eliminating the gain dead zone at the output end and reducing front-end heat density. This ensures that the beam quality remains consistently excellent across the entire power range of 10W to 150W, resulting in a high beam quality factor. It smoothly approaches the ideal diffraction limit (approximately 1.1 to 1.2).

[0078] In summary, the multi-parameter collaborative optimization method of this application effectively solves the physical contradiction between power enhancement and beam quality degradation in traditional resonant pumping schemes, and achieves the dual goals of high power output and high beam quality without increasing the total pump power.

[0079] It should be noted that the above is only an optional example and should not be construed as a limitation of this application.

[0080] Compared with existing technologies, this application determines the initial range of the length and doping concentration of the gain medium, establishes a target optimization function based on the effective pump spot radius, and determines the specific beam waist position of the pump light. It then performs physical constraint verification on the determined specific beam waist position of the pump light. Based on the effective pump spot radius determined by the optimized specific beam waist position, it calculates the thermal load temperature within the gain medium to dynamically adjust the length and doping concentration of the gain medium to obtain the optimal parameter combination. Through multi-parameter synergistic optimization, the resonant pumped solid-state laser system is optimized so that the local gain throughout the entire length of the gain medium is always higher than the absorption loss, eliminating the gain death region. Without increasing the total pump power, the slope efficiency of the system in this application is improved by more than 15%.

[0081] Furthermore, by eliminating the gain death region, a higher beam quality and brighter output beam were obtained; the thermal management advantages of low-doped crystals were fully utilized, reducing the risk of thermal damage.

[0082] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems or apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0083] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A resonant-pumped solid-state laser system, characterized in that, include: A pump source, used to emit pump light of a specified wavelength; A beam shaping unit, including a first lens and a second lens, is used to collimate and focus the pump light. A resonant cavity, which includes plane mirrors and curved mirrors; A gain medium is located within the resonant cavity. The gain medium has a multi-parameter collaborative optimization architecture, and the optimization parameters include the length and doping concentration of the gain medium. The beam shaping unit determines the specific beam waist position of the pump light by minimizing the effective pump spot radius within the gain medium according to an absorption-weighted minimization strategy. The effective pump spot radius of the pump light within the gain medium is expressed by the following expression: ， in, This represents the effective pump spot radius of the pump light within the gain medium; This indicates the length of the optimized gain medium. denoted by the pump light absorption coefficient, and z represents the position coordinates of the pump light along the propagation direction inside the gain medium; This represents the function representing the variation of the pump spot along the axial direction. ,in, The effective pump spot radius of the pump light within the gain medium. This indicates the focusing position of the pump light, that is, the beam waist position formed by the pump light along the axial direction. The pump light is formed to a specified length, i.e., the Rayleigh length of the pump beam, when it enters the resonant cavity; the length of the optimized gain medium is 20mm to 60mm.

2. The resonant-pumped solid-state laser system according to claim 1, characterized in that, The pump light is positioned at a specific beam waist location within the incident region of the gain medium, and the distance between the location corresponding to the specific beam waist location and the starting point of the incident region of the gain medium is less than a specific length, i.e., satisfying the following expression: ， in, L represents the distance between the location point corresponding to a specific beam waist position and the starting point of the light-incident region of the gain medium; L represents the length of the optimized gain medium.

3. The resonant-pumped solid-state laser system according to claim 1, characterized in that, The length of the gain medium was optimized so that the specified length formed when the pump light enters the resonant cavity satisfies the physical constraint with the length of the optimized gain medium, as expressed by the following expression: ， in, This indicates the Rayleigh length of the pump beam when it enters the resonant cavity, which is the length of the pump beam. ,in, The effective pump spot radius of the pump light within the gain medium is given by n, where n represents the refractive index of the gain medium. This indicates the wavelength of the pump light; The beam quality factor represents the pump source and is used to measure the degree of divergence of the actual beam relative to the ideal Gaussian beam. This indicates the length of the optimized gain medium.

4. The resonant-pumped solid-state laser system according to claim 1, characterized in that, The doping concentration of the gain medium is 0.5 at.% to 2 at.%.

5. The resonant-pumped solid-state laser system according to claim 2 or 3, characterized in that, The length of the gain medium is greater than 30 mm and less than 60 mm.

6. The resonant-pumped solid-state laser system according to claim 1, characterized in that, Based on the change in pump power, the size of the light spot formed by the pump is controlled, and the length and doping concentration of the gain medium are dynamically adjusted.

7. The resonant-pumped solid-state laser system according to claim 6, characterized in that, The pump power is 10W to 100W.

8. The resonant-pumped solid-state laser system according to claim 1, characterized in that, A cooling device is also provided on the outside of the gain medium, which is used to cool and dissipate heat from the gain medium.

9. A multi-parameter collaborative optimization method for a resonant-pumped solid-state laser system, characterized in that, It is performed using the resonant-pumped solid-state laser system according to any one of claims 1 to 8, wherein the multi-parameter collaborative optimization method includes: Determine the initial range of the length of the gain medium and the doping concentration; Establish a target optimization function based on the effective pump spot radius to determine the specific beam waist position of the pump light; Physical constraint verification is performed on the specific beam waist position of the determined pump light; Based on the effective pump spot radius determined by the optimized specific beam waist position, the thermal load temperature in the gain medium is calculated to dynamically adjust the length and doping concentration of the gain medium to obtain the optimal parameter combination.

10. The multi-parameter collaborative optimization method according to claim 9, characterized in that, When the specific beam waist position of the pump light satisfies the physical constraints, it means that the pump intensity at the output end of the gain medium is higher than the inversion distribution threshold. When the determined specific beam waist position of the pump beam does not meet the physical constraints, the beam waist radius of the pump beam is repeatedly increased automatically, and / or the length of the gain medium is adjusted, until the physical constraints are met, so that the specific beam waist position of the pump beam is located in the incident end region of the gain medium.

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