Laser device and method for generating laser light with thermal effect compensation for end-pumping

Abstract

The application discloses a laser device and a method for generating laser, which compensates for thermal effects of end-pumping, and comprises a first pumping source, a second pumping source, a solid laser medium, a mirror and an output mirror; the first pumping source is used for outputting first pumping light which enters the solid laser medium from a large face of the solid laser medium and is directed to a first end face of the solid laser medium; the second pumping source is used for outputting second pumping light which enters the solid laser medium from the large face of the solid laser medium, and the second pumping light is used for compensating for thermal effects of the first pumping light; the solid laser medium generates laser in response to excitation of the first pumping light and the second pumping light; the mirror is used for reflecting laser output from the first end face, and the output mirror is used for reflecting part of laser output from a second end face and outputting laser output from the second end face. The application increases large-face pumping on the basis of end-pumping, compensates for uneven distribution of pumping light caused by end-pumping, and improves pumping power density.

Description

Technical Field

[0001] The present invention relates to the field of solid-state lasers, and more particularly to a laser device for compensating thermal effects of end-face pumping and a method for generating laser light. Background Art

[0002] In the design and application of solid-state lasers, the selection and configuration of the pump source plays a crucial role in the performance of the laser. For example, when using solid-state lasers doped with three-level system ions such as ytterbium (Yb), there are certain difficulties in achieving population inversion because Yb ions belong to a three-level system. This characteristic requires that the doping concentration of Yb ions usually be kept at a low level to avoid reduced laser efficiency due to insufficient population inversion. However, the reduced absorption coefficient caused by low doping results in insufficient effective absorption length of the pump light, which in turn affects the overall output performance of the laser. In order to improve the absorption efficiency of the pump light, it is usually necessary to design the length of the laser medium to be relatively long to increase the interaction between the pump light and the laser medium.

[0003] In terms of pumping method selection, side pumping, due to its short absorption length, can provide a certain degree of pumping efficiency, but in practical applications it often faces problems with low absorption efficiency and insufficient light conversion efficiency. End pumping can significantly increase the absorption length of light, increasing the absorption efficiency of pump light and thus improving light conversion efficiency. However, end pumping has the disadvantage of uneven light intensity distribution. This uneven light intensity distribution not only leads to unstable laser output mode and poor beam quality, but also affects the thermal management and performance stability of the laser. Summary of the Invention

[0004] The present invention provides a laser device for compensating for thermal effects of end-face pumping and a method for generating laser light, so as to solve at least one of the problems existing in the prior art.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A first aspect of the present invention provides a laser device for compensating for thermal effects of end-face pumping, the device comprising a first pump source, a second pump source, a solid laser medium, a reflector, and an output mirror;

[0007] The first pump source is used to output a first pump light that enters the solid laser medium from the large surface of the solid laser medium and is emitted toward the first end surface of the solid laser medium;

[0008] The second pump source is used to output a second pump light that enters the solid laser medium from the large surface of the solid laser medium, and the second pump light is used to compensate for the thermal effect of the first pump light;

[0009] The solid laser medium is used to generate laser light in response to excitation of the first pump light and the second pump light;

[0010] The reflector is used to reflect the laser output from the first end face, and the output mirror is used to reflect part of the laser output from the second end face opposite to the first end face and output the laser output from the second end face of the solid laser medium.

[0011] Optionally, the device also includes a shaping system, which is a pump coupling structure. The pump coupling structure includes a first pump coupling structure and a second pump coupling structure. The first pump coupling structure is used to shape the first pump light and then couple it into the solid laser medium. The second pump coupling structure is used to shape the second pump light and then couple it into the solid laser medium.

[0012] Optionally, the solid laser medium is a slab laser medium or a rod laser medium.

[0013] Optionally, the solid laser medium is a slab laser medium, the first end face and the second end face of the slab laser medium are respectively coated with a reflective film for the first pump light and a reflective film for the fourth pump light, and the first end face and the second end face of the slab laser medium are both coated with an anti-reflection film for the laser; the first large surface and the second large surface of the slab laser medium are respectively coated with an anti-reflection film for the second pump light and an anti-reflection film for the third pump light;

[0014] The solid laser medium is a rod-shaped laser medium. A first plane mirror for reflecting the first pump light and a second plane mirror for reflecting the fourth pump light are respectively provided on both sides of the first end face and the second end face of the rod-shaped laser medium. The first plane mirror and the second plane mirror are also used to transmit laser light. The first end face and the second end face of the rod-shaped laser medium are respectively coated with an anti-reflection film for the first pump light and an anti-reflection film for the fourth pump light.

[0015] Optionally, the device further comprises a cooling module disposed on a large surface of the solid laser medium away from the second pump source, for cooling the solid laser medium.

[0016] Optionally, the device further includes a third pump source for outputting a third pump light that enters the solid laser medium from the large surface of the solid laser medium;

[0017] The solid laser medium is configured to generate laser light in response to excitation by the first pump light, the second pump light, and the third pump light.

[0018] Optionally, the device further includes a fourth pump source for outputting a fourth pump light that enters the solid laser medium from the large surface of the solid laser medium and is emitted toward the second end surface of the solid laser medium;

[0019] The solid laser medium is configured to generate laser light in response to excitation by the first pump light, the second pump light, and the fourth pump light.

[0020] Optionally, the device further includes a fifth pump source for outputting a fifth pump light that enters the solid laser medium from the large surface of the solid laser medium and is emitted toward the second end surface of the solid laser medium;

[0021] The solid laser medium is used to generate laser light in response to excitation by the first pump light, the second pump light, the third pump light and the fifth pump light;

[0022] The fifth pump source and the fourth pump source are the same pump source.

[0023] The second aspect of the present invention provides a method for generating laser light by a laser device for compensating thermal effects of end-face pumping, the method comprising:

[0024] Outputting, through a first pump source, a first pump light that enters the solid laser medium from a large surface of the solid laser medium and is emitted toward a first end surface of the solid laser medium;

[0025] outputting, through a second pump source, a second pump light entering the solid laser medium from a large surface of the solid laser medium, and compensating for a thermal effect of the first pump light through the second pump light;

[0026] generating laser light by the solid laser medium;

[0027] The laser output from the first end face of the solid laser medium is reflected by a reflection mirror, and the laser output from the second end face opposite to the first end face is partially reflected by an output mirror, and the laser output from the second end face of the solid laser medium is output.

[0028] Optionally, compensating the thermal effect of the first pump light by the second pump light includes:

[0029] The intensity of the second pump light is controlled by adjusting the parameters of the second pump coupling structure to compensate for the thermal effect caused by the first pump light.

[0030] The beneficial effects of the present invention are as follows:

[0031] The present invention adds a large-surface pumping method to the end-face pumping of a solid laser medium. The large-surface pumping compensates for the thermal effect caused by the end-face pumping, thereby improving the pump power density of the laser device. It also compensates for the uneven distribution of pump light caused by the exponential absorption characteristics of the end-face pumping, realizes the complementary distribution of pump light between the end face and the large surface, and makes the mixed pump light in the solid laser medium evenly distributed, thereby improving the beam quality and thermal stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The specific embodiments of the present application are described in further detail below with reference to the accompanying drawings.

[0033] Figure 1 Figure 1 shows a schematic diagram of a laser device for compensating thermal effects of single-end pumping by single-side pumping of a slab laser medium according to the present application;

[0034] Figure 2 Figure 2 shows a schematic diagram of a laser device for compensating thermal effects of single-end pumping by double-side pumping of a slab laser medium according to the present application;

[0035] Figure 3 Figure 3 shows a schematic diagram of a laser device for compensating thermal effects of double-end pumping by single-side pumping of a slab laser medium according to the present application;

[0036] Figure 4 Figure 4 shows a schematic diagram of a laser device for compensating thermal effects of double-end pumping by double-side pumping of a slab laser medium according to the present application;

[0037] Figure 5 Figure 5 shows a schematic diagram of a laser device for compensating thermal effects of double-end pumping by single-side pumping of a rod laser medium according to the present application;

[0038] Figure 6 Figure 6 shows a comparison of output power in the case of only end-face pumping and output power after compensating thermal effects of end-face pumping by adding large-face pumping in an embodiment of the present application;

[0039] Figure 7(a) shows a schematic diagram of the uniformity of pumping light distribution inside a solid laser medium when double-end pumping a slab laser medium in an embodiment of the present application;

[0040] Figure 7(b) shows a schematic diagram of the uniformity of pumping light distribution inside a solid laser medium after compensating thermal effects of double-end pumping by large-face pumping of a slab laser medium in an embodiment of the present application;

[0041] Figure 8(a) shows a schematic diagram of the temperature gradient inside a solid laser medium when double-end pumping a slab laser medium in an embodiment of the present application;

[0042] Figure 8(b) shows a schematic diagram of the temperature gradient inside a solid laser medium after compensating thermal effects of double-end pumping by large-face pumping of a slab laser medium in an embodiment of the present application;

[0043] Figure 9(a) shows a schematic diagram of the thermal stress inside a solid laser medium when double-end pumping a slab laser medium in an embodiment of the present application;

[0044] Figure 9(b) shows a schematic diagram of the thermal stress inside a solid laser medium after compensating thermal effects of double-end pumping by large-face pumping of a slab laser medium in an embodiment of the present application. DETAILED DESCRIPTION

[0045] In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments and accompanying drawings. Similar components in the accompanying drawings are represented by the same reference numerals. It should be understood by those skilled in the art that the following detailed description is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention.

[0046] The present invention provides a laser device for compensating thermal effects of end-face pumping and a method for generating laser light. The laser device includes a first pump source, a second pump source, a solid laser medium, a shaping system, a reflector, and an output mirror, wherein:

[0047] The first pump source is arranged on one side of the first end face of the solid laser medium, and is used to output a first pump light that enters the solid laser medium from the large surface of the solid laser medium and is emitted toward the first end face of the solid laser medium. The first pump source can be a semiconductor LD laser or a stacked array;

[0048] The second pump source is arranged on one side of the large surface of the solid laser medium, and is used to output the second pump light entering the solid laser medium from the large surface of the solid laser medium. The second pump source can be a semiconductor LD laser or a stacked array;

[0049] The solid laser medium is used to generate laser light in response to the excitation of the first pump light and the second pump light. The solid laser medium can be a slab laser medium or a rod laser medium.

[0050] The shaping system is a pump coupling structure, which includes a first pump coupling structure and a second pump coupling structure. The first pump coupling structure is used to adjust the intensity of the first pump light. By controlling the parameters of the first pump coupling structure, the first pump light is shaped to effectively adjust the intensity distribution of the first pump light to meet specific intensity distribution requirements. The first pump coupling structure can be an optical waveguide, a lens, or a combination of an optical waveguide and a lens.

[0051] The second pump coupling structure is used to adjust the intensity of the second pump light. By controlling the parameters of the second pump coupling structure to shape the second pump light, the intensity distribution of the second pump light is effectively adjusted to meet specific intensity distribution requirements. The second pump coupling structure can be an optical waveguide, a lens, or a combination of an optical waveguide and a lens.

[0052] The solid laser medium is used to receive the shaped first pump light and the second pump light to generate laser. The first pump source generates the first pump light, which is shaped by the first pump coupling structure and coupled into the solid laser medium through the first end face of the solid laser medium; the second pump source generates the second pump light, which is shaped by the second pump coupling structure and coupled into the solid laser medium through the large face of the solid laser medium.

[0053] The reflector and the output mirror form a resonant cavity. The reflector is coated with a laser reflective film. The reflector is arranged on the first end face of the solid laser medium and is used to reflect and amplify the laser. The output mirror is arranged on the second end face of the solid laser medium and is used to reflect part of the laser output from the second end face and output the laser beam output from the second end face.

[0054] By controlling the parameters of the second pump coupling structure, the large-surface pumping of the solid laser medium is optimized. The large-surface pumping compensates for the thermal effect caused by the end-face pumping and the uneven distribution of pump light caused by the exponential absorption characteristics of the end-face pumping. The pump light distribution of the end face and the large surface is complementary, so that the mixed pump light is evenly distributed in the entire solid laser medium.

[0055] The laser device also includes a cooling module, which is arranged on the large surface of the solid laser medium away from the second pump source and is used to cool the solid laser medium. The solid laser medium can be cooled by welding a heat sink or setting a cooling liquid channel.

[0056] The pumping mode of the solid laser medium end face is single-end pumping or double-end pumping; the pumping mode of the large surface is single-side pumping or double-side pumping.

[0057] Figure 1 This is a schematic diagram of a laser device for compensating for the thermal effect of single-ended pumping by single-sided pumping of a slab laser medium according to the present invention. The end face pumping mode of the slab laser medium 1 is single-ended pumping, and the large face pumping mode is single-sided pumping. A first pumping light is output by a first pumping source 2, entering the slab laser medium 1 from the large face and reflected from the first end face into the interior of the slab laser medium 1. A second pumping light is output by a second pumping source 4, entering the slab laser medium 1 from the large face. The intensity of the second pumping light is adjusted by adjusting the parameters of a second pump coupling structure 5 to achieve thermal effect compensation for single-ended pumping by large face pumping.

[0058] The slab laser medium 1 generates laser light in response to the excitation of the first pump light and the second pump light. The reflector 6 is used to reflect the laser light output from the first end face, and the output mirror 7 is used to reflect part of the laser light output from the second end face opposite to the first end face and output the laser light output from the second end face of the slab laser medium 1.

[0059] When the end face of the slab laser medium 1 is pumped using single-ended pumping, a monotonically decreasing light intensity distribution is obtained from the pump end to the output end. To compensate for the uneven pump light distribution caused by the exponential absorption characteristics of single-ended pumping, the pump light distribution is optimized by controlling the parameters of the second pump coupling structure on the large face of the slab laser medium 1. This achieves complementary pump light distribution between single-ended pumping and the large face, resulting in a more uniform or balanced distribution in the medium and increased laser output power.

[0060] Figure 2 Schematic diagram of a laser device that compensates for the thermal effects of single-ended pumping through double-sided pumping of a slab laser medium. The end face pumping method of the slab laser medium 1 is single-ended pumping, and the large surface pumping method is double-sided pumping. The pump sources in the device include a first pump source 2, a second pump source 4, and a third pump source 9. The parameters of the second pump coupling structure 5 and the third pump coupling structure 10 are adjusted to adjust the intensities of the second pump light and the third pump light, respectively, to compensate for the thermal effects of the first pump light incident on the first end face.

[0061] The slab laser medium 1 generates laser light in response to the excitation of the first pump light, the second pump light and the third pump light. The reflector 6 is used to reflect the laser light output from the first end face, and the output mirror 7 is used to reflect part of the laser light output from the second end face opposite to the first end face and output the laser light output from the second end face of the slab laser medium 1.

[0062] When the end face of the slab laser medium 1 is pumped using single-ended pumping and the large face is pumped using double-sided pumping, the end face pumping obtains a monotonically decreasing light intensity distribution from the pump end to the output end. By controlling the parameters of the second pump coupling structure and the third pump coupling structure on the large face of the slab laser medium 1, the pump light distribution is optimized to compensate for the uneven pump light distribution caused by the exponential absorption characteristics of single-ended pumping, thereby achieving complementary pump light distribution between single-ended pumping and the large face, and improving the laser output power.

[0063] Figure 3 Schematic diagram of a laser device for compensating for thermal effects of double-ended pumping through single-sided pumping of a slab laser medium. When the end face of the slab laser medium 1 is pumped by double-ended pumping and the large face is pumped by single-sided pumping, the device also includes a fourth pump source 11 and a fourth pump coupling structure 12. The fourth pump source 11 is used to output fourth pump light that enters the solid laser medium from the large face of the slab laser medium 1 and is emitted toward the second end face of the slab laser medium 1. The intensity of the second pump light is adjusted by adjusting the parameters of the second pump coupling structure 5 to compensate for the thermal effects of the first and fourth pump lights incident on the end faces.

[0064] The slab laser medium 1 generates laser in response to the excitation of the first pump light, the fourth pump light and the second pump light. The reflector 6 is used to reflect the laser output from the first end face, and the output mirror 7 is used to reflect part of the laser output from the second end face opposite to the first end face and output the laser output from the second end face of the slab laser medium 1.

[0065] When the end face pumping of the slab laser medium 1 is double-ended pumping, a light intensity distribution with strong light at both ends and weak light in the middle is obtained. By controlling the parameters of the second pump coupling structure on the large surface of the slab laser medium 1, a light intensity distribution with weak light at both ends and strong light in the middle is obtained to compensate for the uneven distribution of pump light caused by the exponential absorption characteristics of double-ended pumping, thereby achieving complementary pump light distribution between double-ended pumping and large surface, and improving the laser output power.

[0066] Figure 4 Schematic diagram of a laser device for compensating for thermal effects of double-ended pumping by double-side pumping of a slab laser device. The device includes a slab laser medium 1, a first pump source 2, a first pump coupling structure 3, a second pump source 4, a second pump coupling structure 5, a reflector 6, an output mirror 7, a cooling module 8, a third pump source 9, a third pump coupling structure 10, a fifth pump source, and a fifth pump coupling structure. The fifth pump source and the fourth pump source 11 are the same pump source, and the fifth pump coupling structure and the fourth pump coupling structure 12 are the same pump coupling structure. The pumping mode of the end face of the slab laser medium 1 is as follows: Double-ended pumping, the large surface is pumped by double-sided pumping. The first pump source 2 and the fourth pump source 11 are used to respectively output the first pump light and the fourth pump light that enter the end face of the slab laser medium 1 from the large surface of the slab laser medium 1 and are reflected to the slab laser medium 1; the second pump source 4 and the third pump source 9 respectively output the second pump light and the third pump light that enter the slab laser medium 1 from the large surface of the slab laser medium 1. The intensities of the second pump light and the third pump light are adjusted respectively by the second pump coupling structure 5 and the third pump coupling structure 10 to compensate for the thermal effect of the first pump light and the fourth pump light incident on the end face.

[0067] The slab laser medium 1 generates laser light in response to the excitation of the first pump light, the second pump light, the third pump light and the fourth pump light. The reflector 6 is used to reflect the laser light output from the first end face, and the output mirror 7 is used to reflect part of the laser light output from the second end face opposite to the first end face and output the laser light output from the second end face of the slab laser medium 1.

[0068] When the end face pumping of the slab laser medium 1 is double-ended pumping, a light intensity distribution with strong light at both ends and weak light in the middle is obtained. By controlling the parameters of the second pump coupling structure and the fourth pump coupling structure on the large surface of the slab laser medium 1, a light intensity distribution with weak light at both ends and strong light in the middle is obtained to compensate for the uneven distribution of pump light caused by the exponential absorption characteristics of double-ended pumping, thereby achieving complementary pump light distribution between double-ended pumping and large surface, and improving the laser output power.

[0069] The solid laser medium is a slab laser medium, and a reflection film for the first pump light and a reflection film for the second pump light are respectively coated on the first end face and the second end face of the slab laser medium, and the first end face and the second end face of the slab laser medium are both coated with an anti-reflection film for the laser; the first large surface and the second large surface of the slab laser medium are respectively coated with anti-reflection films for the third pump light and the fourth pump light.

[0070] Figure 5 This is a schematic diagram of a laser device that compensates for thermal effects of double-end pumping by single-sided pumping of a rod-shaped laser medium. The rod-shaped laser medium is end-pumped using double-end pumping, while the large-surface pumping method is single-sided pumping. The structure of the rod-shaped laser device is similar to that of the slab laser device and will not be described in detail here. The difference is that plane mirrors are placed on both ends of the rod-shaped laser medium, away from the rod-shaped laser medium. These plane mirrors are used to reflect the pump light and transmit the laser light. The device includes a rod-shaped laser medium 13, a first pump source 2, a second pump source 4, a fourth pump source 11, a shaping system, a plane mirror, a reflector 6, and an output mirror 7. The shaping system is a pump coupling structure, including a first pump coupling structure 3, a second pump coupling structure 5, and a fourth pump coupling structure 12. The plane mirrors include a first plane mirror 14 and a second plane mirror 15. The first pump light output by the first pump source 2 is reflected by the first plane mirror 14 to the first end face of the rod-shaped laser medium 13 and enters the rod-shaped laser medium 13. The second pump light output by the second pump source 4 enters the rod-shaped laser medium 13 from the large surface of the rod-shaped laser medium 13. The fourth pump light output by the fourth pump source 11 is reflected by the second plane mirror 15 to the second end face of the rod-shaped laser medium 13 and enters the rod-shaped laser medium 13. In response to the excitation of the first pump light, the second pump light, and the fourth pump light, the rod-shaped laser medium 13 generates laser gain oscillation. The reflector 6 and the output mirror 7 form a resonant cavity. The laser light is output from the first end face of the rod-shaped laser medium 13, transmits through the first plane mirror 14, and reaches the reflector 6. The reflector 6 reflects the laser light back into the rod-shaped laser medium 13, outputs through the second end face of the rod-shaped laser medium 13, transmits through the second plane mirror 15, and reaches the output mirror 7. The laser light is reflected back and forth in the resonant cavity, oscillated, and amplified before being output from the resonant cavity through the output mirror 7. By adjusting the parameters of the second pump coupling structure 5, the intensity of the second pump light is adjusted to achieve compensation for the thermal effect of the large-surface pumping on the double-ended pumping, to compensate for the uneven distribution of pump light caused by the exponential absorption characteristics of the double-ended pumping, to achieve complementary distribution of pump light between the double-ended pumping and the large-surface pumping, and to improve the laser output power.

[0071] The first plane mirror 14 is coated with a reflective film for the first pump light and an anti-reflective film for the laser, and the second plane mirror 15 is coated with a reflective film for the fourth pump light and an anti-reflective film for the laser.

[0072] The device further comprises a cooling module 8 arranged on a side of the rod-shaped laser medium away from the second pump source 4, for cooling the rod-shaped laser medium.

[0073] In a specific embodiment, Figure 3 As shown, a laser device that compensates for the thermal effect of double-ended pumping by single-side pumping of a slab laser medium is taken as an example. The laser device includes a slab laser medium 1, a first pump source 2, a first pump coupling structure 3, a second pump source 4, a second pump coupling structure 5, a fourth pump source 11, a fourth pump coupling structure 12, a reflector 6, an output mirror 7 and a cooling module 8.

[0074] First pump source 2 emits a first pump light, which is shaped by first pump coupling structure 3 and then enters slab laser medium 1 through the large surface of slab laser medium 1. It is then coupled into slab laser medium 1 through reflection from the first end face. Second pump source 4 emits a second pump light, which is shaped by second pump coupling structure 5 and then coupled into slab laser medium 1 through the large surface of slab laser medium 1. Fourth pump source 11 emits a fourth pump light, which is shaped by fourth pump coupling structure 12 and then enters slab laser medium 1 through the large surface of slab laser medium 1 through reflection from the second end face. Slab laser medium 1 generates laser light in response to the excitation of the first, second, and fourth pump lights. Reflector 6 and output mirror 7 form a resonant cavity, where the laser light oscillates and amplifies. The laser light is then reflected and amplified by reflector 6 of the resonant cavity and then output through output mirror 7.

[0075] When the end face pumping of the slab laser medium 1 is double-ended pumping, a light intensity distribution with strong light at both ends and weak light in the middle is obtained. By controlling the parameters of the second pump coupling structure 5 on the large surface of the slab laser medium 1, a light intensity distribution with weak light at both ends and strong light in the middle is obtained to compensate for the uneven distribution of pump light caused by the exponential absorption characteristics of double-ended pumping, thereby achieving complementary distribution of pump light between double-ended pumping and large surface, and improving the laser output power.

[0076] Among them, the first pump source 2, the second pump source 4 and the fourth pump source can be the same pump source or different pump sources, and the first pump coupling structure 3, the second pump coupling structure 5 and the fourth pump coupling structure can be the same pump coupling structure or different pump coupling structures.

[0077] The first end face of the slab laser medium 1 is coated with a first pump light reflecting film and a laser anti-reflection film for reflecting the shaped first pump light and transmitting the laser output by the slab laser medium 1 and the laser reflected by the reflector 6 and the output mirror 7.

[0078] The second end face of the slab laser medium 1 is coated with a fourth pump light reflecting film and a laser anti-reflection film for reflecting the shaped fourth pump light and transmitting the laser output by the slab laser medium 1 and the laser reflected by the reflector 6 and the output mirror 7.

[0079] The second pump light anti-reflection film is coated on the large surface of the slab laser medium 1 close to the second pump source 4, for transmitting the shaped second pump light; the cooling module 8 is welded on the large surface of the slab laser medium 1 away from the second pump source 4, which is a cooling heat sink for cooling the slab laser medium 1.

[0080] In the embodiment, it should be noted that the laser device can be used as a laser amplifier when there is no resonant cavity, and the laser amplifier is used to amplify the intensity of the input light beam, but will not generate a new laser beam output. The atoms or molecules in the solid laser medium are excited by the pump light to produce gain, thereby amplifying the input light (i.e. seed light) passing through the medium. Specifically, the shaped first pump light and the fourth pump light are coupled into the slab laser medium through the end face of the slab laser medium, and the shaped second pump light is coupled into the slab laser medium through the large surface of the slab laser medium. The mixed pump light in the slab laser medium provides gain, amplifies the input seed laser signal, and finally outputs the amplified laser beam. The laser amplifier does not have precise optical feedback in the resonant cavity, which leads to the output light beam not having high directionality and coherence like a laser. Therefore, the beam of the laser amplifier usually has a larger divergence angle and relatively poor coherence.

[0081] In the embodiment, the end face pumping is increased by adding large surface pumping, the design of large surface pumping is optimized by controlling the parameters of the second pump coupling structure, the thermal effect caused by end face pumping is compensated by large surface pumping, and the pump power density of the laser device is improved; the uneven distribution of pump light caused by the exponential absorption characteristics of end face pumping is compensated, the pump light distribution of the end face and the large surface is complementary, the mixed pump light in the entire solid laser medium is uniformly distributed, the formation of temperature gradient is effectively reduced, and the thermal stability is improved; the stress distribution in the solid laser medium is also uniform, the laser device can stably operate at a higher power, and the laser output power limit is further improved, the reliability and service life of the laser are improved. In addition, uniform pump light distribution also reduces the wavefront distortion of the beam, improves the beam quality, and makes it more suitable for high beam quality applications.

[0082] Figure 6The following is a comparison of the output power of this embodiment when end-pumping alone is used, and when large-area pumping is added to compensate for the thermal effects of end-pumping. The end-pumping of slab laser medium 1 uses double-end pumping. The slab laser medium 1 in the laser device is a Yb:YAG slab medium. In the simulation model, the slab dimensions are set to 120mm × 35mm × 5mm, with 120mm along the X-axis, 5mm along the Y-axis, and 35mm along the Z-axis. The basic conditions of the slab are the same. The output power obtained when the device is adjusted to different pump current settings for both end-pumping alone and for thermal effects compensation with large-area pumping is compared, visually demonstrating the output power comparison under different pumping conditions.

[0083] According to the output power under different pumping conditions, when the laser device is adjusted to the same pump current level, the output power obtained after thermal effect compensation is relatively large. That is, after adding large-surface pumping to compensate for the thermal effect of end-face pumping, the pump power density is increased and the laser output power is improved.

[0084] FIG7( a ) is a schematic diagram showing the uniformity of the pump light distribution inside the slab laser medium when the Yb:YAG slab medium is double-ended pumped in this embodiment. FIG7( b ) is a schematic diagram showing the uniformity of the pump light distribution inside the slab laser medium after the Yb:YAG slab medium is subjected to large-surface pumping to compensate for the thermal effect of double-ended pumping in this embodiment. The horizontal axis represents an arbitrary position along the length direction of the X-axis of the Yb:YAG slab medium.

[0085] Figure 7(a) employs a double-ended pumping approach. Due to the exponential absorption of pump light in end-face pumping, which gradually weakens along the length of the slab medium, the pump light intensity is unevenly distributed, with a concave center and convex ends. Specifically, as the pump light propagates through the slab laser medium, the intensity is higher near the two end faces, but gradually weakens with increasing distance. This unevenness directly leads to the formation of temperature gradients, which in turn cause thermal and stress problems. Figure 7(b) employs large-surface pumping to compensate for the thermal effects of double-ended pumping. By adding a large-surface pump to compensate for the thermal effects, the design of the large-surface pump is optimized by controlling the parameters of the second pump coupling structure. This compensates for the uneven pump light distribution caused by the exponential absorption characteristics of the end-face pumping, resulting in significantly more uniform pump light distribution within the slab medium. This complements the pump light distributions at the end faces and the large surface, resulting in a uniform distribution of mixed pump light throughout the slab medium.

[0086] In this embodiment, the thermal effect of end-face pumping is compensated by large-surface pumping, which helps to evenly distribute the pump light inside the slab medium.

[0087] FIG. 8(a) is a schematic diagram of the temperature gradient inside the slab laser medium when double-end pumping is used in the present embodiment, and FIG. 8(b) is a schematic diagram of the temperature gradient inside the slab laser medium after the thermal effect compensation of double-end pumping by large-area pumping is used in the present embodiment. The horizontal and vertical coordinates represent the spatial position of the slab laser medium, and the color steps represent the temperature distribution at different positions.

[0088] FIG. 8(a) shows that the temperature is more concentrated to the edge of the slab medium when double-end pumping is used, resulting in higher temperature at both ends of the slab laser medium and uneven temperature distribution. FIG. 8(b) shows that the temperature distribution inside the slab laser medium is more uniform and the gradient change is smoother without obvious temperature hot spots when the thermal effect compensation of double-end pumping by large-area pumping is used. The temperature gradient changes more gently in the longitudinal and transverse directions of the slab laser medium, and the thermal stability is better. Although the heat source is still concentrated at the incident position of the pump light beam, the thermal effect compensation makes the high-temperature region better diffuse and the temperature distribution tends to be balanced, effectively reducing the formation of the temperature gradient inside the slab laser medium. This not only improves the performance and efficiency of the laser, but also reduces the thermal effect caused by uneven temperature, ensuring the stability of the laser device and prolonging the service life.

[0089] FIG. 9(a) is a schematic diagram of the thermal stress inside the slab laser medium when double-end pumping is used in the present embodiment, and FIG. 9(b) is a schematic diagram of the thermal stress inside the slab laser medium after the thermal effect compensation of double-end pumping by large-area pumping is used in the present embodiment. Based on the further calculation of the temperature field, uneven temperature distribution results in thermal stress. Since the thermal expansion coefficients of different materials are different, the thermal stress will change with the internal temperature of the laser.

[0090] Thermal stress is usually directly related to temperature difference. FIG. 9(a) and FIG. 9(b) show the thermal stress at different positions in the same material. In the case of end-pumping only in FIG. 9(a), the thermal stress is more concentrated near the pump surface and the edge of the material due to the large temperature difference. In FIG. 9(b), the temperature difference is significantly reduced after the thermal effect compensation of end-pumping by large-area pumping, and the thermal stress is more uniformly distributed with a relatively low total amount. This reduces the temperature gradient, effectively reduces the thermal stress, and improves the stability of the laser device. The thermal stress fluctuation and mutation in the present embodiment are smaller than those in the end-pumping only, i.e., the response of the laser device to thermal management is more gentle.

[0091] In one specific embodiment, the solid laser medium of the laser device of the present application is a rod-shaped laser medium, and its principle is the same as that of the first embodiment, which will not be described here.

[0092] The present invention adds large-surface pumping to end-face pumping to compensate for thermal effects. By controlling the parameters of the pump coupling structure on the large-surface side to compensate for the thermal effects caused by end-face pumping, the pump power density of the laser device is increased. The uneven distribution of pump light caused by the exponential absorption characteristics of end-face pumping is compensated, and the pump light distribution of the end face and the large surface is complementary, so that the mixed pump light is evenly distributed throughout the solid laser medium. The present invention reduces the variation of local light intensity, effectively reduces the formation of temperature gradients, and reduces temperature fluctuations within the material, thereby improving thermal stability. The thermal stress distribution within the solid laser medium of the present invention tends to be uniform, reducing the risk of damage caused by thermal stress. The laser device can operate stably at higher powers, thereby improving the laser output power limit and increasing the reliability and service life of the laser. The uniform pump light distribution within the solid laser medium reduces the wavefront distortion of the beam, improves the beam quality, and makes it more suitable for high-beam-quality applications.

[0093] The present invention also provides a method for compensating the thermal effect of an end-pumped laser device, the method comprising:

[0094] Outputting, by a first pump source, a first pump light that enters the solid laser medium from a large surface of the solid laser medium and is emitted toward a first end surface of the solid laser medium;

[0095] outputting a second pumping light through a large surface of the solid laser medium into the solid laser medium through a second pumping source, and thermally compensating the first pumping light through the second pumping light;

[0096] Laser generation by solid laser medium;

[0097] The laser output from the first end face of the solid laser medium is reflected by the reflection mirror, and the laser output from the second end face opposite to the first end face is partially reflected by the output mirror, and the laser output from the second end face of the solid laser medium is output.

[0098] The method also includes shaping the first pump light through a first pump coupling structure; and adjusting the light intensity distribution of the second pump light by adjusting the parameters of the second pump coupling structure so that the pump light in the solid laser medium is evenly distributed to compensate for the thermal effect caused by end-face pumping.

[0099] If the end face is pumped in a single-ended manner, a light intensity distribution that decreases monotonically from the pump end to the output end is obtained. The pump light distribution is optimized by adjusting the parameters of the second pump coupling structure to compensate for the uneven pump light distribution caused by the exponential absorption characteristics of the single-ended pumping, thereby achieving complementary pump light distribution between the single end and the large face, so that the mixed pump light is evenly distributed in the entire medium, thereby improving the laser output power. If the end face is pumped in a double-ended manner, a light intensity distribution that is strong at both ends and weak in the middle is obtained. By adjusting the parameters of the second pump coupling structure, a light intensity distribution that is weak at both ends and strong in the middle is obtained to compensate for the uneven pump light distribution caused by the exponential absorption characteristics of the double-ended pumping, thereby achieving complementary pump light distribution between the double end and the large face, thereby making the mixed pump light evenly distributed in the entire medium, thereby improving the laser output power.

[0100] The present invention reduces the variation amplitude of local light intensity, effectively reduces the formation of temperature gradients, reduces temperature fluctuations inside the material, and thus improves thermal stability; the thermal stress distribution inside the solid laser medium of the present invention tends to be uniform, reducing the risk of damage caused by thermal stress, and the laser device can operate stably at higher power, thereby improving the laser output power limit and increasing the reliability and service life of the laser; the uniform pump light distribution inside the solid laser medium reduces the wavefront distortion of the light beam, improves the beam quality, and makes it more suitable for high beam quality applications.

[0101] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper" and "lower" is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0102] It should also be noted that, in the description of the present invention, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0103] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A laser device for compensating thermal effects of end-face pumping, characterized in that: The device includes a first pump source, a second pump source, a solid laser medium, a reflecting mirror and an output mirror; The first pump source is used to output a first pump light that enters the solid laser medium from the large surface of the solid laser medium and is emitted toward the first end surface of the solid laser medium; The second pump source is used to output a second pump light that enters the solid laser medium from the large surface of the solid laser medium, and the second pump light is used to compensate for the thermal effect of the first pump light; The solid laser medium is used to generate laser light in response to excitation of the first pump light and the second pump light; The reflector is used to reflect the laser light outputted from the first end face, and the output mirror is used to reflect part of the laser light outputted from the second end face opposite to the first end face and output the laser light outputted from the second end face of the solid laser medium; Compensating the thermal effect of the first pump light by using the second pump light includes: The intensity of the second pump light is controlled by adjusting the parameters of the second pump coupling structure to compensate for the thermal effect caused by the first pump light.

2. The device according to claim 1, characterized in that The device also includes a shaping system, which is a pump coupling structure. The pump coupling structure includes a first pump coupling structure and a second pump coupling structure. The first pump coupling structure is used to shape the first pump light and then couple it into the solid laser medium. The second pump coupling structure is used to shape the second pump light and then couple it into the solid laser medium.

3. The device according to claim 1, characterized in that The solid laser medium is a slab laser medium or a rod laser medium.

4. The device according to claim 3, characterized in that The solid laser medium is a slab laser medium, wherein the first end face and the second end face of the slab laser medium are respectively coated with a reflective film for the first pump light and a reflective film for the fourth pump light, and the first end face and the second end face of the slab laser medium are both coated with an anti-reflection film for the laser; the first large surface and the second large surface of the slab laser medium are respectively coated with an anti-reflection film for the second pump light and an anti-reflection film for the third pump light; The solid laser medium is a rod-shaped laser medium. A first plane mirror for reflecting the first pump light and a second plane mirror for reflecting the fourth pump light are respectively provided on both sides of the first end face and the second end face of the rod-shaped laser medium. The first plane mirror and the second plane mirror are also used to transmit laser light. The first end face and the second end face of the rod-shaped laser medium are respectively coated with an anti-reflection film for the first pump light and an anti-reflection film for the fourth pump light.

5. The device according to claim 1, characterized in that The device further comprises a cooling module which is arranged on a large surface of the solid laser medium away from the second pump source and is used for cooling the solid laser medium.

6. The device according to claim 1, characterized in that The device further includes a third pump source for outputting a third pump light that enters the solid laser medium from the large surface of the solid laser medium; The solid laser medium is configured to generate laser light in response to excitation by the first pump light, the second pump light, and the third pump light.

7. The device according to claim 1, characterized in that The device further includes a fourth pump source for outputting a fourth pump light that enters the solid laser medium from the large surface of the solid laser medium and is emitted toward the second end surface of the solid laser medium; The solid laser medium is configured to generate laser light in response to excitation by the first pump light, the second pump light, and the fourth pump light.

8. The device according to claim 6, characterized in that The device further includes a fifth pump source for outputting a fifth pump light that enters the solid laser medium from the large surface of the solid laser medium and is emitted toward the second end surface of the solid laser medium; The solid laser medium is used to generate laser light in response to excitation by the first pump light, the second pump light, the third pump light and the fifth pump light; The fifth pump source and the fourth pump source are the same pump source.

9. A method for generating laser light by a laser device for thermal effect compensation of end-face pumping according to any one of claims 1 to 8, characterized in that: The method includes Outputting, through a first pump source, a first pump light that enters the solid laser medium from a large surface of the solid laser medium and is emitted toward a first end surface of the solid laser medium; outputting, through a second pump source, a second pump light entering the solid laser medium from a large surface of the solid laser medium, and compensating for a thermal effect of the first pump light through the second pump light; generating laser light by the solid laser medium; Reflecting the laser light outputted from the first end face of the solid laser medium through a reflecting mirror, reflecting part of the laser light outputted from the second end face opposite to the first end face through an output mirror, and outputting the laser light outputted from the second end face of the solid laser medium; The compensating the thermal effect of the first pump light by using the second pump light includes: The intensity of the second pump light is controlled by adjusting the parameters of the second pump coupling structure to compensate for the thermal effect caused by the first pump light.

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