Laser device for performing heat effect compensation on end face pump and method for generating laser

Abstract

The invention discloses a laser device for performing heat effect compensation on end face pumping and a method for generating laser. The device comprises a first pumping source, a second pumping source, a solid laser medium, a reflecting mirror and an output mirror, the first pumping source is used for outputting first pumping light which enters the solid laser medium from the large surface of the solid laser medium and is emitted to the first end surface of the solid laser medium; the second pumping source is used for outputting second pumping light entering the solid laser medium from the large surface of the solid laser medium, and the second pumping light is used for performing heat effect compensation on the first pumping light; the solid laser medium generates laser in response to excitation of the first pump light and the second pump light; the reflector is used for reflecting the laser output by the first end face, and the output mirror is used for reflecting part of the laser output by the second end face and outputting the laser output by the second end face. According to the invention, the large-surface pumping is added on the basis of the end-surface pumping, so that the condition of non-uniform distribution of the pumping light caused by the end-surface pumping is compensated, and the pumping power density is improved.

Description

Technical Field

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

[0002] In the design and application of solid-state lasers, the selection and configuration of the pump source plays a vital role in the performance of the laser. For example, when using a solid-state laser doped with three-level system ions such as ytterbium (Yb), since Yb ​​ions belong to a three-level system, there are certain difficulties in achieving population inversion. This characteristic requires that the doping concentration of Yb ions usually needs to be kept at a low level to avoid reduced laser efficiency due to insufficient population inversion. However, the absorption coefficient is reduced due to low doping, which makes the effective absorption length of the pump light insufficient, thereby affecting 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 the choice of pumping method, although side pumping can provide a certain pumping efficiency due to its short absorption length, it often faces the problems of low absorption efficiency and insufficient light conversion efficiency in practical applications. End pumping can significantly increase the absorption length of light, improve the absorption efficiency of pump light, and thus improve the light conversion efficiency. However, end pumping brings 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 the thermal effect of end-face pumping and a method for generating laser, 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 thermal effect compensation 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 reflecting mirror 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, and 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, and 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 face and the second large face 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, and a first plane mirror for reflecting the first pump light and a second plane mirror for reflecting the fourth pump light are respectively arranged 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, and 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 comprises a third pump source for outputting a third pump light entering the solid laser medium from the large surface of the solid laser medium;

[0017] The solid laser medium is used 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 comprises 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 used 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 comprises 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] A 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, 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;

[0025] Outputting, by a second pump source, a second pump light entering the solid laser medium from a large surface of the solid laser medium, and performing thermal effect compensation on the first pump light by the second pump light;

[0026] Generating laser light by means of 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, the compensating the thermal effect of the first pump light by the second pump light includes:

[0029] The light 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 on the basis of end-face pumping of a solid laser medium, and compensates for the thermal effect caused by end-face pumping through large-surface pumping, thereby improving the pump power density of the laser device; compensating for the uneven distribution of pump light caused by the exponential absorption characteristics of end-face pumping, achieving complementary distribution of pump light between the end face and the large surface, making the mixed pump light in the solid laser medium evenly distributed, improving the beam quality, and improving the thermal stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The specific implementation modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0033] Figure 1 A schematic diagram of a laser device for compensating the thermal effect of single-ended pumping by single-side pumping of a slab laser medium according to the present invention is shown;

[0034] Figure 2 A schematic diagram of a laser device for compensating the thermal effect of single-end pumping by double-side pumping of a slab laser medium according to the present invention is shown;

[0035] Figure 3 A schematic diagram of a laser device for compensating the thermal effect of double-end pumping by single-side pumping of a slab laser medium according to the present invention is shown;

[0036] Figure 4 A schematic diagram of a laser device for compensating the thermal effect of double-end pumping by double-side pumping of a slab laser medium according to the present invention is shown;

[0037] Figure 5 A schematic diagram of a laser device for compensating the thermal effect of double-end pumping by single-side pumping of a rod-shaped laser medium according to the present invention is shown;

[0038] Figure 6 A comparison diagram showing the output power of the case of only end pumping in the embodiment of the present invention and the output power of adding large-surface pumping to compensate for the thermal effect of the end pumping;

[0039] FIG. 7( a ) is a schematic diagram showing uniform distribution of pump light inside a solid laser medium when double-end pumping is performed on a slab laser medium in an embodiment of the present invention;

[0040] FIG. 7( b ) is a schematic diagram showing uniform distribution of pump light inside a solid laser medium after thermal effect compensation of double-ended pumping by large-surface pumping of a slab laser medium in an embodiment of the present invention;

[0041] FIG8( a ) is a schematic diagram showing the temperature gradient inside the solid laser medium when double-end pumping is performed on the slab laser medium in an embodiment of the present invention;

[0042] FIG8( b ) is a schematic diagram showing the temperature gradient inside the solid laser medium after the thermal effect of double-ended pumping is compensated by large-surface pumping of the slab laser medium in an embodiment of the present invention;

[0043] FIG9( a ) is a schematic diagram showing the internal thermal stress of the solid laser medium when double-end pumping is performed on the slab laser medium in an embodiment of the present invention;

[0044] FIG9( b ) is a schematic diagram showing the thermal stress inside the solid laser medium after the thermal effect of double-end pumping is compensated by large-surface pumping of the slab laser medium in an embodiment of the present invention. 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 content specifically described below 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 the thermal effect of end-face pumping and a method for generating laser. 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 at one side of the first end face of the solid laser medium, and is used to output the first pump light which enters the solid laser medium from the large surface of the solid laser medium and is emitted to 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 in response to the excitation of the first pump light and the second pump light, and 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 light intensity of the first pump light. The first pump light is shaped by controlling the parameters of the first pump coupling structure to effectively adjust the light intensity distribution of the first pump light to meet specific light 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 light intensity of the second pump light. The second pump light is shaped by controlling the parameters of the second pump coupling structure, and the light intensity distribution of the second pump light is effectively adjusted to meet specific light 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 constitute a resonant cavity. The reflector is coated with a laser reflective film. The reflector is arranged on one side of the first end face of the solid laser medium and is used to reflect and amplify the laser. The output mirror is arranged on one side of 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] The large-surface pumping of the solid laser medium is optimized by controlling the parameters of the second pump coupling structure. The thermal effect caused by the end-face pumping is compensated by the large-surface pumping. The uneven distribution of pump light caused by the exponential absorption characteristics of the end-face pumping is compensated. 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 a 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 end face of the solid laser medium 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 The present invention is a schematic diagram of a laser device for compensating for thermal effects of single-ended pumping by single-side pumping of a slab laser medium. The end face pumping mode of the slab laser medium 1 is single-ended pumping, and the large face pumping mode is single-side pumping. The first pumping source 2 outputs a first pumping light that enters the slab laser medium 1 from the large face and is reflected from the first end face to the inside of the slab laser medium 1. The second pumping source 4 outputs a second pumping light that enters the slab laser medium 1 from the large face. The intensity of the second pumping light is adjusted by adjusting the parameters of the second pump coupling structure 5 to achieve thermal effect compensation of single-ended pumping by large face pumping.

[0058] The slab laser medium 1 generates laser in response to the excitation of the first 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.

[0059] When the pumping mode of the end face of the slab laser medium 1 is single-ended pumping, a monotonically decreasing light intensity distribution from the pump end to the output end is obtained. In order to compensate for the uneven distribution of pump light 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 of the large surface of the slab laser medium 1 to achieve complementarity between the single-ended pumping and the large surface pump light distribution, so that it can achieve a more uniform or balanced distribution in the medium, thereby improving the laser output power.

[0060] Figure 2 Schematic diagram of a laser device for compensating for thermal effects of single-ended pumping by double-sided pumping of a slab laser medium. The end face pumping mode of the slab laser medium 1 is single-ended pumping, and the large face pumping mode 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 respectively to adjust the intensities of the second pump light and the third pump light, so as 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 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 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.

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

[0063] Figure 3 A schematic diagram of a laser device for compensating for thermal effects of double-end pumping by single-side pumping of a slab laser medium, wherein the pumping mode of the end face of the slab laser medium 1 is double-end pumping and the pumping mode of the large face is single-side pumping, the device further comprises a fourth pumping source 11 and a fourth pump coupling structure 12, the fourth pumping source 11 being used to output a fourth pumping 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 pumping light is adjusted by adjusting the parameters of the second pump coupling structure 5, and thermal effects of the first pumping light and the fourth pumping light incident on the end face are compensated.

[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 of 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 double-ended pumping exponential absorption characteristics, thereby achieving complementarity between the double-ended pumping and the large surface pump light distribution and improving the laser output power.

[0066] Figure 4 Schematic diagram of a laser device for compensating the thermal effect of double-end 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, wherein 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: Double-end pumping, the large surface is pumped in a double-sided pumping mode, 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 surface 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, and the intensities of the second pump light and the third pump light are respectively adjusted 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 surface.

[0067] The slab laser medium 1 generates laser 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 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.

[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 of 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 double-ended pumping exponential absorption characteristics, realize the complementarity of the double-ended pumping and the large surface pump light distribution, and improve the laser output power.

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

[0070] Figure 5 The schematic diagram of a laser device for compensating the thermal effect of double-end pumping by single-side pumping of a rod-shaped laser medium is shown. The end face pumping mode of the rod-shaped laser medium is double-end pumping, and the large face pumping mode is single-side pumping. The structure of the rod-shaped laser device is similar to that of the slab laser device, which will not be repeated here. The difference is that plane mirrors are placed on both sides of the two end faces of the rod-shaped laser medium away from the rod-shaped laser medium, and the plane mirrors are used to reflect pump light and transmit 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. Among them, 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, and the plane mirror includes 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 face 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. The rod-shaped laser medium 13 generates laser gain oscillation in response to the excitation of the first pump light, the second pump light and the fourth pump light. The reflector 6 and the output mirror 7 form a resonant cavity. The laser is output from the first end face of the rod-shaped laser medium 13 and then transmits through the first plane mirror 14 to the reflector 6. The reflector 6 reflects the laser back to the rod-shaped laser medium 13, outputs through the second end face of the rod-shaped laser medium 13 and then transmits through the second plane mirror 15 to the output mirror 7. The laser is reflected back and forth in the resonant cavity and oscillates and amplifies, and then outputs the resonant cavity through the output mirror 7. The intensity of the second pump light is adjusted by adjusting the parameters of the second pump coupling structure 5 to achieve compensation for the thermal effect of the large-surface pump on the double-ended pump, to compensate for the uneven distribution of the pump light caused by the double-ended pump exponential absorption characteristics, to achieve complementary distribution of the double-ended pump and the large-surface pump light, and to improve the laser output power.

[0071] The first plane mirror 14 is coated with a reflection film of the first pump light and an anti-reflection film of the laser, and the second plane mirror 15 is coated with a reflection film of the fourth pump light and an anti-reflection film of 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-end 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] The first pumping light emitted by the first pumping source 2 is shaped by the first pump coupling structure 3, and then enters the slab laser medium 1 through the large surface of the slab laser medium 1, and then couples into the slab laser medium 1 through the first end surface reflection; the second pumping light emitted by the second pumping source 4 is shaped by the second pump coupling structure 5, and then couples into the slab laser medium 1 through the large surface of the slab laser medium 1; the fourth pumping light emitted by the fourth pumping source 11 is shaped by the fourth pump coupling structure 12, and then enters the slab laser medium 1 through the large surface of the slab laser medium 1, and then couples into the slab laser medium 1 through the second end surface reflection. The slab laser medium 1 generates laser light in response to the excitation of the first pumping light, the second pumping light, and the fourth pumping light; the reflector 6 and the output mirror 7 constitute a resonant cavity, and the laser light oscillates and amplifies in the resonant cavity, and the laser beam is output through the output mirror 7 after the laser reflection and amplification by the reflector 6 of the resonant cavity.

[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 double-ended pumping exponential absorption characteristics, thereby achieving complementarity between the double-ended pumping and the large surface pump light distribution 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] A first pump light reflection film and a laser anti-reflection film are plated on the first end face of the slab laser medium 1 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 reflection 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] A 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, which is used to transmit the shaped second pump light; a cooling module 8 is welded on the large surface of the slab laser medium 1 away from the second pump source 4, and the cooling module is a cooling heat sink used to cool the slab laser medium 1.

[0080] In this embodiment, it should be noted that when the laser device does not have a resonant cavity, it can be used as a laser amplifier. The function of the laser amplifier is to amplify the intensity of the input light beam, but no new laser beam output is generated. The atoms or molecules in the solid laser medium are excited by the pump light to generate 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 face 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 results in the output light beam not having a high degree of directionality and coherence like a laser. Therefore, the light beam of the laser amplifier usually has a large divergence angle and relatively poor coherence.

[0081] In this embodiment, a method of adding large-surface pumping on the basis of end-face pumping is adopted. The design of large-surface pumping is optimized by controlling the parameters of the second pump coupling structure. The large-surface pumping compensates for the thermal effect caused by end-face pumping, thereby improving the pump power density of the laser device; 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 face is complementary, so that the mixed pump light is evenly distributed in the entire solid laser medium, effectively reducing the formation of temperature gradients and improving thermal stability; the stress distribution inside the solid laser medium also tends to be uniform, and the laser device can operate stably at higher power, thereby improving the laser output power limit and improving the reliability and service life of the laser. In addition, the uniform pump light distribution also reduces the wavefront distortion of the beam and improves the beam quality, making it more suitable for high beam quality applications.

[0082] Figure 6The following is a comparison chart of the output power of this embodiment in the case of end pumping only and the output power of adding large-surface pumping to compensate for the thermal effect of end pumping. Among them, the end pumping method of the slab laser medium 1 adopts double-end pumping, and the slab laser medium 1 in the laser device adopts Yb:YAG slab medium. In the simulation calculation model, the slab size is set to 120mm×35mm×5mm, of which the size along the X-axis direction is 120mm, the size along the Y-axis direction is 5mm, and the size along the Z-axis direction is 35mm. The basic conditions of the slab are the same. The output power obtained when the device is adjusted to different pump current gears in the two cases of single end pumping and adding large-surface pumping to compensate for the thermal effect of end pumping is compared to intuitively show the effect comparison of output power 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 gear, 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 uniform distribution of pump light 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 uniform distribution of pump light inside the slab laser medium after thermal effect compensation of double-ended pumping is performed by large-surface pumping in this embodiment, wherein the horizontal axis represents an arbitrary position in the length direction of the X-axis of the Yb:YAG slab medium.

[0085] Figure 7(a) adopts the double-end pumping method. Since the exponential absorption of the pump light in the end-face pumping gradually weakens along the length direction of the slab medium, the pump light intensity is unevenly distributed. The distribution of the pump light is concave in the middle and convex at both ends. That is, when the pump light propagates in the slab laser medium, the light intensity is higher near the two end faces, and as the distance increases, the light intensity gradually weakens. This unevenness directly leads to the formation of temperature gradients, which in turn causes thermal and stress problems. Figure 7(b) adopts the method of large-face pumping to compensate for the thermal effect of double-end pumping. Large-face pumping is added to compensate for the thermal effect. The design of large-face pumping is optimized by controlling the parameters of the second pump coupling structure, compensating for the uneven distribution of pump light caused by the exponential absorption characteristics of the end-face pumping, making the pump light distribution in the slab medium more uniform, achieving complementary pump light distribution at the end face and large face, and making the mixed pump light uniformly distributed in the entire slab medium.

[0086] This embodiment uses large-surface pumping to compensate for the thermal effect of end-surface pumping, which helps to evenly distribute the pump light inside the slab medium.

[0087] FIG8(a) is a schematic diagram of the temperature gradient inside the slab laser medium during double-end pumping in this embodiment, and FIG8(b) is a schematic diagram of the temperature gradient inside the slab laser medium after the thermal effect of double-end pumping is compensated by large-surface pumping in this embodiment. The horizontal and vertical axes represent the spatial positions of the slab laser medium, respectively, and the color scale represents the temperature distribution at different positions.

[0088] Figure 8(a) uses double-end pumping, and the temperature is more concentrated at the edge of the slab medium, resulting in higher temperatures at both ends of the slab laser medium and uneven temperature distribution. Figure 8(b) uses large-surface pumping to compensate for the thermal effect of double-end pumping. By adjusting the parameters of the second pump coupling structure to adjust the intensity of the second pump light, the temperature distribution inside the slab laser medium is more uniform, the gradient change is smoother, and there is no obvious temperature hot spot; the temperature gradient changes more gently in the depth and lateral direction of the slab laser medium, and the thermal stability is better; and although the heat source is still concentrated at the incident position of the pump beam, the thermal effect compensation allows the high-temperature area to obtain better thermal diffusion, the temperature distribution tends to be balanced, and the formation of temperature gradient inside the slab laser medium is effectively reduced. This not only improves the performance and efficiency of the laser, but also reduces the thermal effect caused by uneven temperature, ensures the stability of the laser device, and extends its life.

[0089] Figure 9(a) is a schematic diagram of the thermal stress inside the slab laser medium during double-end pumping in this embodiment, and Figure 9(b) is a schematic diagram of the thermal stress inside the slab laser medium after the thermal effect of double-end pumping is compensated by large-surface pumping in this embodiment. Based on further calculation of the temperature field, the temperature distribution is uneven, thereby generating thermal stress. Due to the different thermal expansion coefficients of different materials, thermal stress will be generated as the temperature inside the laser changes.

[0090] Thermal stress is usually directly related to temperature difference. Figures 9(a) and 9(b) show the magnitude of thermal stress at different locations in the same material. In Figure 9(a), when only end-face pumping is used, due to the large temperature difference, the distribution of thermal stress is particularly concentrated near the pumping surface and at the edge of the material. In Figure 9(b), after adding large-surface pumping to compensate for the thermal effect of end-face pumping, the temperature difference is significantly reduced, the thermal stress is more evenly distributed, and the total amount is relatively low, which reduces the temperature gradient, effectively reduces thermal stress, and improves the stability of the laser device. In this embodiment, when adding large-surface pumping to compensate for the thermal effect of end-face pumping, the fluctuation and mutation of thermal stress are smaller than those of the single end-face pumping method, that is, the laser device responds more gently to thermal management.

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

[0092] The present invention adds large-surface pumping on the basis of end-face pumping to compensate for thermal effects. The thermal effects caused by end-face pumping are compensated by controlling the parameters of the pump coupling structure on one side of the large surface, thereby improving the pump power density of the laser device; 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 in the entire solid laser medium. 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 improving 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 light 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 for thermal effect compensation, 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 second pumping source and entering the solid laser medium from a large surface of the solid laser medium, and thermally compensating the first pumping light through the second pumping light;

[0096] Laser generation by means of a 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 the first pump coupling structure; 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 pumping mode of the end face is single-ended pumping, 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 single-ended pumping exponential absorption characteristics, and the single-ended and large-face pump light distributions are complementary, so that the mixed pump light is evenly distributed in the entire medium, and the laser output power is improved; if the pumping mode of the end face is double-ended pumping, a light intensity distribution that is strong at both ends and weak in the middle is obtained. The light intensity distribution that is weak at both ends and strong in the middle is obtained by adjusting the parameters of the second pump coupling structure to compensate for the uneven pump light distribution caused by the double-ended pumping exponential absorption characteristics, and the double-ended and large-face pump light distributions are complementary, so that the mixed pump light is evenly distributed in the entire medium, and the laser output power is improved.

[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 a higher power, thereby improving the laser output power limit, and improving 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 light 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 terms "upper", "lower", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are 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 position, be constructed and operated in a specific position, 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 an indirect connection through an intermediate medium, or it can be a connection between the 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 only used 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 "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including 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 protection scope 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 reflector 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 reflecting mirror 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.

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, the first end face and the second end face of the slab laser medium are respectively coated with a reflection film of the first pump light and a reflection film of 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 of the laser; the first large face and the second large face of the slab laser medium are respectively coated with an anti-reflection film of the second pump light and an anti-reflection film of the third pump light; The solid laser medium is a rod-shaped laser medium, and a first plane mirror for reflecting the first pump light and a second plane mirror for reflecting the fourth pump light are respectively arranged 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, and 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 also includes 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 also 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 used 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 used 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, 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; Outputting, by 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 thermal effects of the first pump light by the second pump light; Generating laser light by means of the solid laser medium; 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.

10. The method according to claim 9, characterized in that The compensating the thermal effect of the first pump light by using the second pump light includes: The light 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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