A high-order Hermitian-Gaussian laser generator

Abstract

This utility model discloses a high-order Hermit-Gaussian laser generator, comprising a pump source for providing laser light, and a first lens, a laser gain medium, a second lens, and an output coupling mirror arranged coaxially along the laser direction emitted from the pump source. The laser gain medium and the output coupling mirror are spaced apart and form a laser resonant cavity. The second lens is movably disposed within the laser resonant cavity and is positioned close to the laser gain medium along the laser direction emitted from the pump source to form a fundamental mode Gaussian beam. By performing an off-axis translation of the second lens in a plane perpendicular to the laser direction emitted from the pump source, the fundamental mode Gaussian beam is converted into a high-order Hermit-Gaussian laser beam, which is then output through the output coupling mirror. This method can replace the off-axis pumping method used in the prior art to generate a high-order Hermit-Gaussian laser beam to obtain a vortex laser.

Description

Technical Field

[0001] This utility model relates to the field of laser technology, and in particular to a high-order Hermitian-Gaussian laser generator. Background Technology

[0002] Vortex lasers have broad application prospects in quantum optics, optical imaging, laser material processing and optical measurement, and the mainstream technical approach to obtaining vortex lasers is to use a pair of cylindrical lenses to perform mode conversion on a one-dimensional high-order Hermitian-Gaussian laser.

[0003] Currently, Hermitian-Gaussian lasers are mainly obtained through pump light spatial modulation. This method uses a semiconductor coupling module and a laser crystal is end-pumped after passing through a dichroic mirror. The laser crystal is usually a small rod or cuboid structure. In a fixed resonant cavity structure, the pump light is translated up, down, left, and right by a translation stage, or the excitation and selection of specific spatial modes are achieved by adjusting the angle of the concave cavity mirror, so as to generate high-order Hermitian-Gaussian laser beams of different orders. However, this modulation method is difficult to operate and the operation steps are relatively complex. Utility Model Content

[0004] To address the aforementioned problems, this invention provides a high-order Hermitian-Gaussian laser generator that can replace the pump light spatial modulation method used in the prior art to generate high-order Hermitian-Gaussian laser beams.

[0005] To achieve the above objectives, the technical solution provided by this utility model is as follows:

[0006] This invention provides a high-order Hermitian-Gaussian laser generator, comprising a pump source for providing laser light, and a first lens, a laser gain medium, a second lens, and an output coupling mirror arranged coaxially along the direction of the laser light emitted from the pump source. The laser gain medium and the output coupling mirror are spaced apart and form a laser resonant cavity. The second lens is movably disposed within the laser resonant cavity. The first lens is used to focus the laser light generated by the pump source into the laser resonant cavity. The laser gain medium is used to absorb the laser light focused by the first lens and form population inversion. The second lens is brought close to the laser gain medium along the direction of the laser light emitted from the pump source to form a fundamental mode Gaussian beam. The fundamental mode Gaussian beam is then converted into a high-order Hermitian-Gaussian laser beam by off-axis translation of the second lens in a plane perpendicular to the direction of the laser light emitted from the pump source, and then output through the output coupling mirror.

[0007] Furthermore, the second lens is a plano-convex lens with a focal length of 10–40 mm.

[0008] Furthermore, it also includes a multi-dimensional displacement stage; the laser emitted by the pump source is parallel to the Z-axis direction, the second lens is mounted on the moving end of the multi-dimensional displacement stage, and the multi-dimensional displacement stage is used to drive the second lens to move along the Z-axis direction and to perform off-axis translation in the X-axis and Y-axis directions in a plane perpendicular to the Z-axis direction.

[0009] Furthermore, it also includes an installation platform, on which the pump source, the first lens, the laser gain medium, the second lens, and the output coupling mirror are respectively mounted; the multidimensional displacement stage is disposed on one side of the installation platform perpendicular to the Z-axis direction.

[0010] Furthermore, the first lens is fixedly mounted on the mounting platform, and the distance between the laser gain medium and the first lens is the focal length of the first lens.

[0011] Furthermore, an input coupling mirror is provided at one end of the laser gain medium facing the pump source. The input coupling mirror and the output coupling mirror are both plane mirrors, so that the laser resonant cavity is a flat cavity. The distance between the input coupling mirror and the output coupling mirror is 10-20 mm greater than the focal length of the second lens.

[0012] Furthermore, the input coupling mirror is coated with a double-layer film, and its transmittance is greater than 95% between wavelengths of 400 and 800 nm, and its reflectance is greater than 99.6% between wavelengths of 800 nm and 2100 nm; the output coupling mirror is coated with a single-layer film, and its transmittance is 2 to 15% between wavelengths of 800 nm and 2100 nm.

[0013] Furthermore, the first lens is a plano-convex lens.

[0014] Furthermore, the matrix of the laser gain medium is a yttrium vanadate matrix, yttrium aluminum garnet matrix, lithium yttrium fluoride matrix, yttrium aluminate matrix, glass matrix, tungstate matrix, or potassium lanthanum barium sodium fluoride matrix doped with rare earth ions; the doping concentration of the rare earth ions is 0.2-10%, and the length of the crystal formed by the rare earth ions along its light propagation direction is 2-15 mm.

[0015] Furthermore, the pump source is a single-mode fiber laser with an output wavelength of 400–2100 nm; or the pump source is a single-mode fiber-coupled semiconductor laser, and its output wavelength is matched to the absorption wavelength of the laser gain medium, with an average output power of 0–400 W.

[0016] The technical solution provided by this utility model has the following beneficial effects:

[0017] By gradually and slowly bringing the second lens closer to the laser gain medium along the direction of the laser emitted from the pump source until a fundamental Gaussian beam is formed, and then by performing an off-axis translation of the second lens in a plane perpendicular to the direction of the laser emitted from the pump source, such as an off-axis translation along the X-axis or Y-axis respectively, and by increasing the translation amount, breaking the symmetry of the laser resonator, the fundamental Gaussian beam oscillating back and forth in the laser resonator is transformed into a higher-order Hermitian-Gaussian laser beam. Part of the higher-order Hermitian-Gaussian laser beam is output through the output coupling mirror. This can replace the pump light spatial modulation method used in the prior art to obtain a higher-order Hermitian-Gaussian laser beam, effectively reducing the difficulty of operation, and the operation steps are also relatively simple. Attached Figure Description

[0018] Figure 1 The diagram shown is a schematic representation of the high-order Hermitian-Gaussian laser generator in this embodiment.

[0019] Figure 2 The image shows a schematic diagram of the first and second lenses in the embodiment. Detailed Implementation

[0020] To further illustrate the various embodiments, the present invention provides accompanying drawings. These drawings are part of the disclosure of the present invention and are mainly used to illustrate the embodiments, and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these drawings, those skilled in the art should be able to understand other possible implementations and the advantages of the present invention. The components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0021] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0022] Reference Figure 1 and Figure 2 This embodiment provides a high-order Hermite-Gaussian laser generator (hereinafter referred to as the laser generator). In a solid-state laser system, the output of high-order Hermite-Gaussian mode (i.e., Hermite-Gaussian modes or HG mode) is achieved through the cooperation of various optical components, so that the high-order Hermite-Gaussian laser can be converted into a vortex laser in the next step. The converted vortex laser can be applied to multiple fields such as optical communication, precision measurement, and material processing.

[0023] like Figure 1As shown, the laser generating device of this embodiment includes a pump source 1 for providing laser or pump light, and a first lens 2, a laser gain medium 3, a second lens 4 and an output coupling mirror 6 arranged coaxially along the direction of the laser emitted from the pump source 1. The direction of the laser emitted from the pump source 1 is parallel to the Z-axis direction (i.e., the front and back directions), and the laser gain medium 3 and the output coupling mirror 6 are perpendicular to the propagation axis of the pump light emitted from the pump source 1 at angles.

[0024] The laser gain medium 3 and the output coupling mirror 6 are arranged with a front-to-back distance to form a laser resonant cavity 8. The second lens 4 is movably disposed in the laser resonant cavity 8, and the first lens 2 is used to focus the laser generated by the pump source 1 into the laser resonant cavity 8. The laser gain medium 3 is used to absorb the laser focused by the first lens 2 and form a population inversion.

[0025] In a specific implementation, the laser generating device of this embodiment also includes a multidimensional displacement stage 5 and a mounting platform 8. The pump source 1, the first lens 2, the laser gain medium 3, the second lens 4, and the output coupling mirror 6 are respectively mounted on the mounting platform 8. The multidimensional displacement stage 5 is set on one side of the mounting platform 8 perpendicular to the Z-axis direction (such as the left or right side in the X-axis direction), and the second lens 4 is mounted on the moving end of the multidimensional displacement stage 5. The multidimensional displacement stage 5 drives the second lens 4 to move along the Z-axis direction and to perform off-axis translation in the X-axis and Y-axis directions in a plane perpendicular to the Z-axis direction.

[0026] More specifically, pump source 1 is a single-mode fiber laser with an output wavelength of 400–2100 nm.

[0027] The matrix of the laser gain medium 3 is a yttrium vanadate matrix doped with rare earth ions. An input coupling mirror 31 is provided at one end of the laser gain medium 3 facing the pump source 1. The input coupling mirror 31 and the output coupling mirror 6 are both plane mirrors, so that the laser resonant cavity 8 is a flat-flat cavity structure.

[0028] Also, such as Figure 2 As shown, the first lens 2 and the second lens 4 are both plano-convex lenses, and the focal length of the second lens 4 is 10-40mm.

[0029] like Figure 1 As shown, the first lens 2 is fixedly mounted on the mounting platform 8. When in use, the distance between the first lens 2 and the laser gain medium 3 is the focal length of the first lens 2, so as to focus the pump light passing through the first lens 2.

[0030] In addition, when using the laser generator in this embodiment, the pump source 1 is first powered on to generate pump light in the Z-axis direction. The fixed position of the first lens 2 on the mounting platform 8 focuses the pump light onto the laser gain medium 3 and into the laser resonant cavity 8. Then, the angles of the laser gain medium 3 and the output coupling mirror 6 are adjusted so that they are perpendicular to the propagation axis of the pump light, so as to ensure that the pump light oscillates back and forth multiple times in the laser resonant cavity 8, thereby obtaining laser output.

[0031] Then adjust the placement angle of the first lens 2 until the center position of the pump beam after focusing is at the center of the front end surface of the laser gain medium 3, and the laser gain medium 3 generates a Gaussian beam with a wavelength of 800nm ​​to 2100nm when irradiated by the pump light.

[0032] Then, the second lens 4 is inserted into the laser resonant cavity 8 through the multidimensional displacement stage 5, and the initial position of the second lens 4 in the laser resonant cavity 8 is made closer to the output coupling mirror 6, and the center of the second lens 4 is aligned with the propagation axis of the pump light.

[0033] Next, the multidimensional displacement stage 5 is adjusted to slowly move the second lens 4 towards the laser gain medium 3 along the propagation axis of the pump light until a fundamental Gaussian beam is output. Then, the moving end of the multidimensional displacement stage 5 is finely adjusted to make the second lens 4 translate off-axis in the X or Y axis direction. As the translation amount increases, the symmetry of the resonant cavity is broken. Therefore, the laser output mode will change from the fundamental Gaussian beam to a higher-order HG mode. That is, the fundamental Gaussian beam oscillating back and forth in the laser resonant cavity 8 will be transformed into a higher-order Hermitian-Gaussian laser beam. Part of the higher-order Hermitian-Gaussian laser beam is output through the output coupling mirror 6, ultimately obtaining a vortex laser. However, due to the excessive off-axis displacement of the second lens 4, a large amount of loss is introduced, therefore the laser generator in this embodiment will no longer be able to output a laser beam.

[0034] By gradually and slowly bringing the second lens 4 closer to the laser gain medium 3 along the laser direction emitted by the pump source 1 until a fundamental mode Gaussian beam is formed, the second lens 4 is then translated off-axis in a plane perpendicular to the laser direction emitted by the pump source 1, such as off-axis translation in the X-axis or Y-axis direction. As the translation amount increases, the symmetry of the laser resonator 8 is broken, so as to transform the fundamental mode Gaussian beam oscillating back and forth in the laser resonator 8 into a higher-order Hermitian-Gaussian laser beam. Part of the higher-order Hermitian-Gaussian laser beam is output through the output coupling mirror 6. This can replace the pump light spatial modulation method used in the prior art to obtain a higher-order Hermitian-Gaussian laser beam, effectively reduce the operation difficulty, and the operation steps are also relatively simple.

[0035] Of course, in other embodiments, the pump source 1 can also be a single-mode fiber-coupled semiconductor laser, and its output wavelength is matched with the absorption wavelength of the laser gain medium 3, with an average output power of 0 to 400 W.

[0036] Furthermore, the matrix of the laser gain medium 3 can also be a rare earth ion-doped yttrium aluminum garnet matrix, yttrium lithium fluoride matrix, yttrium aluminate matrix, glass matrix, tungstate matrix, or potassium lanthanum barium sodium fluoride matrix.

[0037] More preferably, the distance between the input coupling mirror 31 and the output coupling mirror 6 is 10-20 mm longer than the focal length of the second lens 4, which is beneficial for the rapid formation of the fundamental mode Gaussian beam.

[0038] More preferably, the rare earth ion doping concentration of the matrix of the laser gain medium 3 is 0.2-10%, and the length of the crystal formed by the rare earth ions along its light propagation direction is 2-15 mm, so as to further play a laser gain role.

[0039] More preferably, the input coupling mirror 31 is coated with a double-layer film, and its transmittance is greater than 95% in the wavelength range of 400-800nm ​​and its reflectance is greater than 99.6% in the wavelength range of 800nm-2100nm. The output coupling mirror 6 is coated with a single-layer film, and its transmittance is 2-15% in the wavelength range of 800nm-2100nm. This is beneficial for generating a laser beam in the wavelength range of 800-2100nm.

[0040] Although the present invention has been specifically shown and described in conjunction with preferred embodiments, those skilled in the art should understand that various changes in form and detail may be made to the present invention without departing from the spirit and scope of the present invention as defined in the appended claims, and all such changes shall be within the scope of protection of the present invention.

Claims

1. A high-order Hermitian-Gaussian laser generator, characterized in that: It includes a pump source for providing laser light, and a first lens, a laser gain medium, a second lens, and an output coupling mirror arranged coaxially along the direction of the laser light emitted from the pump source. The laser gain medium and the output coupling mirror are spaced apart to form a laser resonant cavity, and the second lens is movably disposed within the laser resonant cavity; the first lens is used to focus the laser generated by the pump source into the laser resonant cavity; the laser gain medium is used to absorb the laser focused by the first lens and form population inversion; The second lens approaches the laser gain medium along the laser direction emitted by the pump source to form a fundamental Gaussian beam. Then, by translating the second lens off-axis in a plane perpendicular to the laser direction emitted by the pump source, the fundamental Gaussian beam is converted into a higher-order Hermitian-Gaussian laser beam, which is then output through the output coupling mirror.

2. The high-order Hermitian-Gaussian laser generator according to claim 1, characterized in that: The second lens is a plano-convex lens with a focal length of 10–40 mm.

3. The high-order Hermitian-Gaussian laser generator according to claim 1 or 2, characterized in that: It also includes a multi-dimensional displacement stage; the laser emitted by the pump source is parallel to the Z-axis direction, the second lens is mounted on the moving end of the multi-dimensional displacement stage, and the multi-dimensional displacement stage is used to drive the second lens to move along the Z-axis direction and to perform off-axis translation in the X-axis and Y-axis directions in a plane perpendicular to the Z-axis direction.

4. The high-order Hermitian-Gaussian laser generator according to claim 3, characterized in that: It also includes an installation platform, on which the pump source, the first lens, the laser gain medium, the second lens and the output coupling mirror are respectively mounted; the multidimensional displacement stage is disposed on one side of the installation platform perpendicular to the Z-axis direction.

5. The high-order Hermitian-Gaussian laser generator according to claim 4, characterized in that: The first lens is fixedly mounted on the mounting platform, and the distance between the laser gain medium and the first lens is the focal length of the first lens.

6. The high-order Hermitian-Gaussian laser generator according to claim 1 or 2, characterized in that: An input coupling mirror is provided at one end of the laser gain medium facing the pump source. The input coupling mirror and the output coupling mirror are both plane mirrors to make the laser resonant cavity a flat cavity. The distance between the input coupling mirror and the output coupling mirror is 10-20 mm greater than the focal length of the second lens.

7. The high-order Hermitian-Gaussian laser generator according to claim 6, characterized in that: The input coupling mirror is coated with a double-layer film, and its transmittance is greater than 95% between wavelengths of 400 and 800 nm, and its reflectance is greater than 99.6% between wavelengths of 800 nm and 2100 nm; the output coupling mirror is coated with a single-layer film, and its transmittance is 2 to 15% between wavelengths of 800 nm and 2100 nm.

8. The high-order Hermitian-Gaussian laser generator according to claim 1 or 2, characterized in that: The first lens is a plano-convex lens.

9. The high-order Hermitian-Gaussian laser generator according to claim 1 or 2, characterized in that: The matrix of the laser gain medium is a yttrium vanadate matrix, yttrium aluminum garnet matrix, lithium yttrium fluoride matrix, yttrium aluminate matrix, glass matrix, tungstate matrix, or potassium lanthanum barium sodium fluoride matrix doped with rare earth ions; the doping concentration of the rare earth ions is 0.2-10%, and the length of the crystal formed by the rare earth ions along its light propagation direction is 2-15 mm.

10. The high-order Hermitian-Gaussian laser generator according to claim 1 or 2, characterized in that: The pump source is a single-mode fiber laser with an output wavelength of 400–2100 nm; or the pump source is a single-mode fiber coupled semiconductor laser, and its output wavelength is matched to the absorption wavelength of the laser gain medium, with an average output power of 0–400 W.

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