High-power vortex beam generating device and packaging method thereof

Abstract

The invention relates to a high-power vortex beam generating device and a packaging method thereof. The device comprises a base, a light gathering cavity is fixedly connected to the base, a columnar gain crystal is arranged in the middle of the light gathering cavity, one side of the gain crystal is fixedly connected to the base, and a plurality of light passing windows are evenly formed in the light gathering cavity; a semiconductor laser bar array group is arranged in the light passing window, and one side, far away from the gain crystal, of the semiconductor laser bar array group is fixedly connected with a heat sink; the end face of one side, far away from the base, of the gain crystal is provided with a plurality of sector ring steps which are arranged from thin to thick clockwise or anticlockwise. According to the high-power vortex beam generation device, the phase modulation sector ring step is directly machined on the end face of the gain crystal, so that the vortex beam is generated through phase modulation, the limitation that the damage threshold value of a traditional phase modulation device is low is broken through, and the output power of the vortex beam is fundamentally improved.

Description

Technical Field

[0001] This invention relates to the field of vortex lasers, specifically to a high-power vortex beam generating device and its packaging method. Background Technology

[0002] Vortex beams, with their helical wavefront structure and orbital angular momentum characteristics, have been widely used in fields such as mode-division multiplexing optical communication, quantum high-dimensional entanglement, optical tweezers rotating particles, super-resolution imaging, femtosecond 3D laser processing, and strong-field attosecond radiation sources. From improving data transmission capacity to manipulating living cells, sculpting micro- and nano-structures, and generating X-ray vortices, their applications span multiple cutting-edge fields such as communication, biology, manufacturing, and strong-field physics, demonstrating broad development prospects.

[0003] However, existing technologies still face bottlenecks in generating high-power vortex beams: on the one hand, the damage threshold of external modulation devices (such as spatial light modulators and spiral phase plates) is low, making it impossible to directly modulate high-power, high-energy vortex lasers using a fundamental Gaussian mode; on the other hand, direct intracavity generation is limited by low amplification efficiency of higher-order modes and intense mode competition, resulting in vortex beams output by laser amplifiers generally not exceeding the fifth order, with power levels and beam quality far lower than those of a fundamental Gaussian beam under the same conditions. These challenges restrict the further development of vortex beams towards higher power and higher beam quality. Therefore, there is an urgent need for a vortex beam generation device that can increase vortex beam power, enhance higher-order mode power, and improve vortex beam quality. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a high-power vortex beam generating device and its packaging method, which can effectively increase the power of the vortex beam, increase the power of higher-order modes, and effectively improve the quality of the vortex beam.

[0005] Terminology Explanation: YAG crystal: refers to yttrium aluminum garnet crystal, i.e., Y3Al5O 12 .

[0006] The technical solution of the present invention is as follows: This invention provides a high-power vortex beam generating device, comprising a base, a focusing cavity fixedly connected to the base, a columnar gain crystal disposed in the center of the focusing cavity, one side of the gain crystal fixedly connected to the base, and a plurality of light-transmitting windows uniformly disposed on the focusing cavity; a semiconductor laser bar array group disposed within each light-transmitting window, and a heat sink fixedly connected to the side of the semiconductor laser bar array group away from the gain crystal; a plurality of fan-shaped steps arranged in a clockwise or counterclockwise direction from thin to thick are disposed on the end face of the gain crystal away from the base, the radius and central angle of the plurality of fan-shaped steps being equal, and the thickness of the fan-shaped steps varying with the azimuth angle. The relationship of change is as follows: ; in, h ( ) is in azimuth angle Thickness at that point, λ For the operating wavelength, For the target topological load number, n The refractive index of the gain crystal, The azimuth angle (from 0 to 2π) is the angle of rotation around the center.

[0007] According to a preferred embodiment of the present invention, the gain crystal is an Nd:YAG gain crystal, with Nd... 3+ Ions are used as activating ions, and YAG crystals are used as the matrix material.

[0008] According to a preferred embodiment of the present invention, the number of semiconductor laser bar array groups is the same as the number of fan ring steps, the positions of the semiconductor laser bar array groups and the fan ring steps correspond, and the light emission center of the semiconductor laser bar array groups is aligned with the geometric center of the corresponding fan ring steps.

[0009] According to a preferred embodiment of the present invention, the gain crystal has a hollow structure and is filled with white polytetrafluoroethylene.

[0010] According to a preferred embodiment of the present invention, the end face of the gain crystal on the side with the fan ring step is a stepped end face, and the stepped end face is coated with an antireflection film.

[0011] According to a preferred embodiment of the present invention, the end face of the gain crystal on the side away from the fan ring step is a planar end face, and the planar end face is coated with a total reflection film.

[0012] The present invention also provides a packaging method for the above-mentioned high-power vortex beam generating device.

[0013] A packaging method for a high-power vortex beam generating device includes the following steps: The semiconductor laser bar array is sintered onto the heat sink, and each semiconductor laser bar array is connected in series with wires. The heat sink, focusing cavity and gain crystal are fixed on the base. The gain crystal is filled with polytetrafluoroethylene, thus completing the encapsulation of the high-power vortex beam generation device.

[0014] Technical features and beneficial effects of the present invention: 1. The device of the present invention achieves phase modulation to generate vortex beams by directly processing phase modulation steps on the end face of the gain crystal, breaking through the limitation of low damage threshold of traditional phase modulation devices and fundamentally improving the output power of vortex beams.

[0015] 2. The device of the present invention uses a hollow gain crystal and fills it with white high-temperature resistant polytetrafluoroethylene material to suppress laser fundamental mode oscillation, increase higher-order mode power, and further improve vortex beam power.

[0016] 3. The device of the present invention uses multiple semiconductor laser bar arrays to uniformly surround the gain crystal for irradiation. The number of semiconductor laser bar arrays and the fan ring steps are the same and their positions correspond. The pump beam is gathered by the focusing cavity, so that the pump light field is uniform and regular, and the beam quality of the vortex beam is improved. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the high-power vortex beam generating device provided in Embodiment 1 of the present invention; Figure 2 This is a cross-sectional view of the gain crystal provided in Embodiment 1 of the present invention; Figure 3 This is a vortex beam diagram provided in Embodiment 1 of the present invention; The components are: 1. Gain crystal, 2. Concentrating cavity, 3. Semiconductor laser bar array, 4. Heat sink, and 5. Base. 11. Flat end face; 12. Stepped end face; 13. Polytetrafluoroethylene (PTFE). Detailed Implementation

[0018] The present invention will be further described below with reference to embodiments and accompanying drawings, but is not limited thereto. The described embodiments are some embodiments of the present invention. Based on these embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," etc., indicating the orientation or positional relationship are only for the convenience of describing this invention and simplifying the description, and should not be construed as limiting this invention.

[0020] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. Unless otherwise specified in the embodiments of the present invention, all techniques existing in the art can be used.

[0021] Example 1 like Figures 1-2As shown, a high-power vortex beam generating device includes a base 5, a focusing cavity 2 fixedly connected to the base 5, a columnar gain crystal 1 (Nd:YAG gain crystal) disposed in the center of the focusing cavity 2, one side of the gain crystal 1 being fixedly connected to the base 5, and eight light-transmitting windows uniformly disposed on the focusing cavity 2; a semiconductor laser bar array group is disposed within the light-transmitting window, and a heat sink 4 is fixedly connected to the side of the semiconductor laser bar array group away from the gain crystal 1; each semiconductor laser bar array group includes two semiconductor laser bar arrays 3 arranged axially, and each semiconductor laser bar array 3 includes two semiconductor laser bars closely arranged circumferentially, for a total of 32 semiconductor laser bars; the output wavelength of each semiconductor laser bar is 808nm, and the maximum output power is 200W; the pump laser generated by the semiconductor laser bars pumps the gain crystal 1 through the light-transmitting holes on the focusing cavity 2, with a total pump power of 6400W.

[0022] The end face of the gain crystal 1 away from the base 5 has eight fan-shaped steps arranged clockwise from thin to thick. The radius and central angle of the fan-shaped steps are equal. The geometric center of the fan-shaped steps is aligned with the light emission center of the corresponding semiconductor laser bar array group. The thickness of the fan-shaped steps varies with the azimuth angle. The relationship of change is as follows: ; in, h ( ) is in azimuth angle Thickness at that point, λ For the operating wavelength, For the target topological load number, n Let be the refractive index of gain crystal 1. The azimuth angle (from 0 to 2π) is the angle of rotation around the center.

[0023] Operating wavelength in this embodiment λ The target topological charge number is 1064nm. The refractive index of gain crystal 1 is 1. n The azimuth angle is 1.82 for the 8-fan ring steps. The values ​​are 1 / 4π, 1 / 2π, 3 / 4π, 1π, 5 / 4π, 3 / 2π, 7 / 4π, and 2π, respectively. The calculated thicknesses of the eight fan-ring steps are 73nm, 146nm, 219nm, 292nm, 365nm, 438nm, 512nm, and 585nm.

[0024] The gain crystal 1 has a hollow structure and is filled with white high-temperature resistant polytetrafluoroethylene 13. The pump light is reflected between the inner wall of the focusing cavity 2 and the white high-temperature resistant polytetrafluoroethylene 13, which ultimately achieves uniform pump light distribution and improves the beam quality of the vortex beam. In addition, the polytetrafluoroethylene 13 filling the gain crystal 1 can suppress the fundamental mode oscillation, increase the output power of higher-order modes, and maintain the stable high-power output of the vortex beam.

[0025] The end face of the gain crystal 1 on the side with the fan ring step is a stepped end face 12, and the stepped end face 12 is coated with a 1064nm antireflection film; the end face of the gain crystal 1 on the side away from the fan ring step is a planar end face 11, and the planar end face 11 is coated with a 1064nm total reflection film. The two faces form a resonant cavity, so that the 1064nm photons generated by the gain crystal 1 pumped by the 808nm semiconductor laser bar oscillate.

[0026] The packaging method for the above-mentioned high-power vortex beam generating device includes the following steps: The semiconductor laser bar array 3 is sintered onto the heat sink 4, and each semiconductor laser bar array 3 is connected in series with wires. The heat sink 4, the focusing cavity 2 and the gain crystal 1 are fixed on the base 5. The gain crystal 1 is filled with polytetrafluoroethylene 13, thus completing the encapsulation of the high-power vortex beam generating device.

[0027] In use, a quasi-continuous current of 200A is input to the semiconductor laser bar array 3. The semiconductor laser bar array 3 emits a laser pump gain crystal 1, and the stepped end face 12 of the gain crystal 1 outputs a vortex beam, such as... Figure 3 As shown.

Claims

1. A high-power vortex beam generating device, characterized in that, The device includes a base, on which a focusing cavity is fixedly connected. A columnar gain crystal is disposed in the center of the focusing cavity, and one side of the gain crystal is fixedly connected to the base. Multiple light-transmitting windows are uniformly arranged on the focusing cavity. A semiconductor laser bar array is disposed within each light-transmitting window, and a heat sink is fixedly connected to the side of the semiconductor laser bar array away from the gain crystal. Multiple fan-shaped steps arranged from thin to thick in a clockwise or counterclockwise direction are disposed on the end face of the gain crystal away from the base, and the radii and central angles of the multiple fan-shaped steps are equal.

2. The high-power vortex beam generating device according to claim 1, characterized in that, The thickness of the fan-shaped step varies with azimuth angle. The relationship of change is as follows: ； in, h ( ) is in azimuth angle Thickness at that point, λ For the operating wavelength, For the target topological load number, n The refractive index of the gain crystal, The azimuth angle (from 0 to 2π) is the angle of rotation around the center.

3. The high-power vortex beam generating device according to claim 1, characterized in that, The gain crystal is an Nd:YAG gain crystal, with Nd... 3+ Ions are used as activating ions, and YAG crystals are used as the matrix material.

4. The high-power vortex beam generating device according to claim 1, characterized in that, The number of semiconductor laser bar array groups is the same as the number of fan ring steps, and the positions of the semiconductor laser bar array groups and the fan ring steps correspond to each other.

5. The high-power vortex beam generating device according to claim 1, characterized in that, The light-emitting center of the semiconductor laser bar array is aligned with the geometric center of the corresponding fan ring step.

6. The high-power vortex beam generating device according to claim 1, characterized in that, The gain crystal has a hollow structure and is filled with white polytetrafluoroethylene.

7. The high-power vortex beam generating device according to claim 1, characterized in that, The gain crystal has a stepped end face on the side with the fan ring step, and the stepped end face is coated with an anti-reflection film.

8. The high-power vortex beam generating device according to claim 1, characterized in that, The gain crystal has a planar end face on the side away from the fan ring step, and the planar end face is coated with a total reflection film.

9. A packaging method for a high-power vortex beam generating device, used for packaging the high-power vortex beam generating device according to claim 1, characterized in that, Including the following steps: The semiconductor laser bar array is sintered onto the heat sink, and each semiconductor laser bar array is connected in series with wires. The heat sink, focusing cavity and gain crystal are fixed on the base. The gain crystal is filled with polytetrafluoroethylene, thus completing the encapsulation of the high-power vortex beam generation device.

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