Single crystal optical fiber growing device based on hollow pentagonal prism

Abstract

The invention belongs to the field of single crystal optical fiber preparation, and discloses a single crystal optical fiber growth device and method based on a hollow pentagonal prism. A beam splitter prism; a beam expanding system; a planar mirror; two spatial light debuggers; self-manufacturing a hollow pentagonal prism; a parabolic mirror; a rotating electrical machine system. According to the invention, the SLM is used for replacing a large-size conical lens, so that the light path adjustment difficulty is reduced; the beam splitter prism is introduced into the optical system, so that various single crystal optical fibers with different diameters can be grown at the same time, and the production efficiency is improved; the hollow pentagonal prism is used as a reflector of an optical system, so that the stability of an optical path is improved, and the high-quality single-crystal optical fiber is obtained.

Description

Technical Field

[0001] The present invention belongs to but is not limited to the technical field of single crystal optical fiber preparation, and in particular relates to a single crystal optical fiber growth device based on a hollow pentagonal prism. Background Art

[0002] Single crystal fiber is an optical fiber made of single crystal material. It not only has the chemical and physical properties of single crystal material, but also has the advantages of optical fiber. Such as anti-electromagnetic interference, good light transmission, small size, light weight, etc. Single crystal fiber can be used in crystal fiber lasers, crystal fiber frequency doublers, holographic data storage, high temperature detection, infrared laser transmission and other fields. Especially in the field of high temperature detection, high temperature single crystal fiber can be used for high temperature measurement above 1800℃, and this method has the advantages of high accuracy, high resolution, fast response, continuous measurement, etc. compared with traditional methods.

[0003] The two most commonly used methods for preparing single-crystal optical fibers are the μ-PD method and the laser-heated pedestal method. The μ-PD method uses microchannel technology, i.e., hot melt, to grow crystals. The LHPG method is a micro-optical floating zone method that focuses a circular CO2 laser beam on the top of the raw material rod to form a micro-melting zone, and then introduces the seed crystal into the melt and pulls it upward for crystal growth. This is currently the only way to grow high-quality single-crystal optical fibers with a diameter of 100 microns.

[0004] Currently, LHPG technology uses a biconical lens design to produce a collimated annular light ring. The annular light ring is focused by a turning mirror and a parabolic mirror to form a heated melting area. The seed crystal is immersed in the heating area and slowly pulled upward to form a single crystal optical fiber.

[0005] In view of the above analysis, the technical problems that need to be solved urgently in the prior art are:

[0006] The current mainstream LHPG technology solution has many degrees of freedom in optical path adjustment, and the optical path adjustment process is relatively cumbersome. Due to the huge size of the annular spot, this method requires large-size (about 80mm in diameter) lenses and reflectors, and has strict processing accuracy requirements. Its optical path adjustment is also relatively complex. In addition, the traditional LHPG system can only produce one single-crystal optical fiber, and the production efficiency is not high.

[0007] Precise alignment of the optical path is the key to ensuring high-quality optical fiber growth. The deflection of optical devices will affect the uniformity of the light field, causing defects in the grown optical fiber and reducing its optical quality. Summary of the invention

[0008] In view of the problems existing in the prior art, the present invention provides a single crystal optical fiber growth device and method based on a hollow pentagonal prism.

[0009] The present invention is implemented as follows: a single crystal optical fiber growth device based on a hollow pentagonal prism, characterized in that the single crystal optical fiber growth device based on a hollow pentagonal prism includes: a carbon dioxide (CO2) laser; a beam splitter; a beam expansion system; a plane reflector; two spatial light adjusters; a homemade hollow pentagonal prism; a parabolic reflector; and a rotating motor system.

[0010] Furthermore, the carbon dioxide laser is used to emit laser, the beam waist diameter of the emitted laser is 2.5mm, the beam quality is M2<1.25, the central wavelength is 10.6μm, the average power is 25w~140w, the power stability is <1%, and the laser type is a continuous laser.

[0011] The lens of the laser beam expander is made of ZnSe material, has an operating wavelength of 10.6 μm, a magnification of 4-8 times, and a maximum light output diameter of 29.4 mm.

[0012] The plane reflector is made of fused quartz, with gold-plated surface, reflectivity R>99.5%, working wavelength of 10.6 μm, diameter of 25.4 mm, thickness of 3 mm, and incident angle of 45°.

[0013] The spatial light modulator (SLM) is made of ZnSe material and has an operating wavelength of 10.6 μm.

[0014] The specially made hollow pentagonal prism includes two gold-plated working reflection surfaces, one of which has upper and lower through holes through which the crystal source rod can pass. The outgoing light beam of the spatial light modulator passes through the first reflection surface to the second reflection surface. The angle between the two reflection surfaces is 45°. When the light is reflected by the two working surfaces, the light beam is deflected by 90°.

[0015] Another object of the present invention is to provide a method for growing a single crystal optical fiber based on a hollow pentagonal prism, the method specifically comprising:

[0016] S1: Use a carbon dioxide laser to emit laser light, and split it into two laser beams to form two subsystems;

[0017] S2: Use a spatial light modulator (SLM) to shape the laser Gaussian beam into a Bessel ring beam;

[0018] S3: A hollow pentagonal prism is used to achieve a 90° deflection of the light path, and the incoming light beam is reflected and focused to the top of the prefabricated source rod, forming a ring-shaped heating area to achieve the growth of special optical fibers.

[0019] Further, the operation steps of the laser heating base method include:

[0020] (1) The single crystal optical fiber and the preform source are grown with a diameter reduction ratio of 1:3;

[0021] (2) After the single crystal fiber grows to the required length, the feeding system is turned off, and the pulling device continues to pull the single crystal fiber off, gradually reducing the laser power;

[0022] (3) Turn off the carbon dioxide laser, and then take the single crystal fiber out of the pulling device to obtain the single crystal fiber.

[0023] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0024] The present invention uses a hollow pentagonal prism to replace a plane reflector. The structure of the hollow pentagonal prism uses two reflectors at an angle of 45° as working surfaces. After the light beam enters the hollow pentagonal prism, the light beam is directionally deflected by 90°. The special feature of the hollow pentagonal prism is that the second reflector is provided with a through hole that passes through from top to bottom, and the crystal rod extends upward through the through hole to the laser heating melting zone. The main advantage of the hollow pentagonal prism is that when the pentagonal prism is deflected, it does not affect the exit position of the reflected light. The intervention of the pentagonal prism can make the modulation of our optical system more convenient.

[0025] With respect to the traditional LHPG optical system, only one single crystal optical fiber can be prepared at a time, and the production efficiency is not high. The present invention provides an optical system, which is applied to a special optical fiber growth device, and a beam splitter prism is used to split the laser beam into two beams. The beam splitter prism is located after the laser emits the laser and after the beam expansion system. Two sub-beams of different powers and directions are emitted through a beam splitter prism. Two subsystems for optical fiber growth are built (the optical structure principles of the subsystems are similar). The device can be used to prepare single crystal optical fibers of different specifications, diameters, and different materials.

[0026] The present invention adopts a reflective spatial light modulator to modulate a Gaussian beam into a Bessel annular beam. Compared with the shaping by two coaxial conical lenses of the traditional system, the use of a reflective spatial light modulator greatly reduces the modulation work of the beam shaping system. The optical path system has a simple structure and does not require a complicated optical path adjustment process, because the traditional LHPG technical solution is to transform the Gaussian beam into an annular beam through a conical lens group and then focus it on the top of the crystal rod. However, it is difficult for the geometric optical axis of the annular beam to coincide with the optical axis of the conical lens, thereby increasing the complexity of the optical path adjustment. The use of a spatial light modulator greatly reduces the difficulty of beam shaping, and uses fewer optical devices to form an annular light spot, which can improve the uniformity of laser heating, simplify the degree of freedom of the optical path, and avoid a series of problems caused by excessive freedom of the optical path, which has important use significance.

[0027] In summary, the advantages and positive effects of the present invention are as follows:

[0028] Replace the reflector with a hollow pentagonal prism: Using a hollow pentagonal prism as a reflector in the optical system can suppress its own deflection effect (that is, a slightly larger deflection angle will not affect the alignment of the optical path), improve the stability of the optical path, and thus obtain high-quality single-crystal optical fiber.

[0029] Simplify the optical path: Use SLM to replace large-sized aconic lenses to reduce the difficulty of optical path adjustment;

[0030] Growing multiple optical fibers simultaneously: Introducing a beam splitter into the optical system allows the simultaneous growth of multiple single-crystal optical fibers of different diameters, thus improving production efficiency; BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of a dual-fiber drawing device based on SLM and hollow pentagonal prism provided in an embodiment of the present invention;

[0032] Figure 2 It is a specially made hollow pentagonal prism diagram provided by an embodiment of the present invention;

[0033] Figure 3 1. It is a light path diagram and an expanded diagram of a pentaprism provided by an embodiment of the present invention;

[0034] Figure 4 is a simplified diagram of the optical path of a hollow pentagonal prism provided in an embodiment of the present invention;

[0035] Figure 5 It is a reflection light path diagram of a plane mirror and a reflection light path diagram of a hollow pentagonal prism provided in an embodiment of the present invention;

[0036] Figure 6 is a flow chart of a single crystal optical fiber growth method based on a hollow pentagonal prism provided by an embodiment of the present invention;

[0037] Figure 7 It is a light path simulation diagram and a detector detection diagram of an ideal hollow pentagonal prism provided by an embodiment of the present invention;

[0038] Figure 8 It is a light path simulation diagram and a detector detection diagram of a hollow pentagonal prism rotated 2° clockwise provided by an embodiment of the present invention;

[0039] Fig. 9 It is a light path simulation diagram and a detector detection diagram of a hollow pentagonal prism rotated 2° counterclockwise provided by an embodiment of the present invention;

[0040] Fig.10 It is a light path simulation diagram and a detector detection diagram of an ideal case of a plane reflector provided by an embodiment of the present invention;

[0041] Fig.11This is a light path simulation diagram and a detector detection diagram of a plane reflector rotated 2° counterclockwise provided by an embodiment of the present invention;

[0042] Fig.12 This is a light path simulation diagram and a detector detection diagram of a plane reflector rotated 2° clockwise provided by an embodiment of the present invention;

[0043] In the figure: 11, carbon dioxide (CO2) laser; 21, beam splitter prism; 31, 32, beam expansion system; 41, plane reflector; 51, 52, two spatial light adjusters; 61, 62, homemade hollow pentagonal prism; 71, 72, parabolic reflector; 81, 82, rotating motor system. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0045] The embodiment of the present invention provides a single crystal optical fiber growth device based on a hollow pentagonal prism, which is a special optical fiber growth device. The special optical fiber growth device includes an optical system, a preformed source rod, a seed optical fiber, a feeding system and a pulling device. The seed optical fiber is placed in the molten zone at the top of the preformed source rod. The feeding system can be used to deliver the preformed source rod upward during the growth of the special optical fiber. Special optical fibers are not limited to single crystal optical fibers, but also photonic crystal optical fibers, glass optical fibers, plastic optical fibers or multifunctional optical fibers.

[0046] Figure 1 The schematic diagram of the structure of the optical system applied to the special optical fiber growth device of the present invention is disclosed. The optical system of the embodiment of the present invention is respectively from right to left: a carbon dioxide (CO2) laser 11; a beam splitter prism 21; a beam expansion system 31, 32; a plane reflector 41; two spatial light adjusters 51, 52; a self-made hollow pentagonal prism 61, 62; a parabolic reflector 71, 72, and a rotating motor system 81, 82.

[0047] The optical system of the present invention is intended for the growth of special single crystal optical fibers, and through a carefully designed combination of optical elements, efficient and precise laser transmission and control are achieved. The system includes, from right to left, a carbon dioxide (CO2) laser 11, a beam splitter prism 21, beam expansion systems 31 and 32, a plane mirror 41, two spatial light modulators 51 and 52, homemade hollow pentagonal prisms 61 and 62, parabolic mirrors 71 and 72, and rotating motor systems 81 and 82.

[0048] The light source of the optical system is a carbon dioxide (CO2) laser 11, which can generate a high-power infrared laser beam as a heat source during the growth of special single-crystal optical fibers. The laser beam first enters a beam splitter prism 21, which is used to adjust the energy distribution of the incident laser according to the set splitting ratio to ensure the uniformity of the optical power in the subsequent optical path system, while reducing the damage to the optical components caused by the excessive local energy of the laser beam.

[0049] The laser beam coming out of the beam splitter 21 enters the beam expansion system 31 and 32. The beam expansion system is composed of multiple lenses. Its main function is to increase the spot size and improve the collimation of the beam, thereby optimizing the focusing effect of the laser. The beam after expansion passes through the plane reflector 41. The function of the plane reflector is to change the propagation direction of the laser so that it enters the spatial light modulator 51 and 52 according to a specific optical path, ensure the uniform distribution of light energy, and pre-adjust the laser phase to meet the needs of subsequent light field distribution.

[0050] After the laser beam enters the spatial light modulators 51 and 52, the modulator dynamically adjusts the phase distribution of the laser to achieve precise control of the spot shape and energy density. This link is particularly important because the growth process of single-crystal optical fiber requires a uniform and stable light field to prevent defects in the crystal structure. The modulated light beam further enters the homemade hollow pentagonal prisms 61 and 62. The function of these prisms is to change the propagation path of the light beam and perform multiple internal reflections to achieve multi-angle uniform irradiation of the light beam, making the thermal field of the growth area more uniform. The laser beam after passing through the hollow pentagonal prisms 61 and 62 is further focused by parabolic reflectors 71 and 72 to form a focal area with high power density, thereby meeting the growth requirements of single-crystal optical fiber. First, the carbon dioxide laser 11 is used as a high-power laser source to generate a stable laser beam. The laser beam first passes through the beam splitter prism 21. The function of the beam splitter prism is to divide the laser beam into multiple beams according to a specific ratio to meet the requirements of different power and energy distribution during the optical fiber growth process. Next, the split laser beam enters the beam expansion system 31 and 32. The beam expansion system is composed of a series of lenses, and its function is to expand the diameter of the laser beam and reduce the divergence angle of the beam, thereby improving the control accuracy of the laser beam by subsequent optical elements.

[0051] The expanded laser beam passes through the plane reflector 41, changing its propagation direction so that it can accurately enter the two spatial light modulators 51 and 52. The function of the spatial light modulator is to accurately modulate the phase, amplitude and wavefront of the laser beam to ensure that the laser beam has the required light field distribution and intensity distribution. This is crucial for controlling the growth morphology and quality of single crystal optical fiber, and can achieve precise control of the optical fiber diameter and crystal structure.

[0052] The modulated laser beam enters the self-made hollow pentagonal prisms 61 and 62. The hollow pentagonal prism, through its special pentagonal internal reflection structure, causes the laser beam to be totally reflected multiple times inside, changing the propagation path and focusing characteristics of the beam. In this way, the laser beam can be evenly focused on a specific growth area, improving energy utilization. Subsequently, the laser beam is further collected and focused by parabolic reflectors 71 and 72, which accurately focus the laser beam on the growth point of the single crystal optical fiber, ensuring uniform melting and crystallization of the optical fiber material at high temperature.

[0053] Finally, the rotary motor systems 81 and 82 are connected to the growth base and are responsible for driving the growth of the single crystal optical fiber.

[0054] A carbon dioxide laser can be used to emit laser light. In some embodiments, the central wavelength of the carbon dioxide laser is 10.57 to 10.63 μm. The type of laser light emitted by the carbon dioxide laser may include a continuous or quasi-continuous laser. The laser light emitted by the carbon dioxide laser has a beam waist diameter of 2.5 mm, a beam quality of M2 <1.25, a central wavelength of 10.6 μm, an average power of 25 w to 140 w, a power stability of <1%, and a continuous laser.

[0055] An ordinary beam splitter prism splits an incident light beam into reflected light and transmitted light at the surface. The beam splitter prism can be made of ZnSe material, with a size of 20*20mm, a height of 20mm, an operating wavelength of 10.6μm, and a transmission-reflection ratio of 20:80.

[0056] Laser beam expanders are used to reduce the divergence angle of laser beams by expanding the diameter of laser beams. The lens of the beam expander in this optical system is made of ZnSe material, with an operating wavelength of 10.6μm, a magnification of 4-8 times, and a maximum light output diameter of 29.4mm.

[0057] The plane reflector is used to change the direction of the light path. The material is fused quartz, the surface is gold-plated, the reflectivity R>99.5%, the working wavelength is 10.6μm, the diameter is 25.4mm, the thickness is 3mm, and the incident angle is 45°.

[0058] The spatial light modulator (SLM) is made of ZnSe material, has an operating wavelength of 10.6 μm, and is able to convert a Gaussian beam profile into an Airy disk intensity distribution.

[0059] The special hollow pentagonal prism is composed of two gold-plated working reflective surfaces, one of which is hollow, and the crystal source rod can pass through it. The outgoing light beam of the spatial light modulator passes through the first reflective surface to the second reflective surface. The angle between the two reflective surfaces is 45°. When the light is reflected by the two working surfaces, the light beam is deflected by 90°. The structure diagram of the special hollow pentagonal prism is as follows: Figure 2 Shown on the left. Figure 2Shown on the right is a simplified diagram of the light path through a pentaprism.

[0060] Figure 3 The figure is a light path diagram and an expanded diagram of a pentagonal prism provided by an embodiment of the present invention. The hollow pentagonal prism is based on the working principle of the pentagonal prism, and the entire pentagonal prism is replaced by two working surfaces. Therefore, the internal working medium of the hollow pentagonal prism is air, and the light will be refracted twice and reflected twice when it enters and exits the pentagonal prism. After the light enters the hollow pentagonal prism, it will not be refracted, but only reflected twice.

[0061] Deflecting light by 90° is one of the characteristics of a pentagonal prism, and a hollow pentagonal prism still has this characteristic. A hollow pentagonal prism has two reflective working interfaces, but the interior is a hollow structure. Under the premise that the angle between the two reflective mirror surfaces remains at 45°, the pentaprism still has the characteristic of deflecting light by 90°.

[0062] Ideally, the angle between the two reflective working surfaces of the special hollow pentagonal prism is 45°. No matter what the angle of the incident light is, the deflection angle of the outgoing light relative to the incident light in the main section is 90°, such as Figure 4 As shown, assuming that the light beams are all located within the main interface, the light is incident at an angle of θ1 degrees, and the working medium of the hollow pentagonal prism is air, so no refraction occurs. The two reflecting surfaces of the hollow pentagonal prism are equivalent to a double-sided mirror, and the angle between them is equal to 45°. According to the reflection principle of the plane mirror, then:

[0063] ∠BCD=∠DCE=2×45°=90°

[0064] Optical path deflection angle δ = ∠BCD = 90°

[0065] According to the above formula, within the range of angles at which light can be reflected, when light is incident at a certain angle, the deflection angle between the outgoing light and the incident light is always 90°.

[0066] The present invention utilizes the characteristic of a hollow pentagonal prism to deflect the outgoing light and the incident light by 90 degrees, thereby replacing the conventional plane mirror to reflect the light. Figure 5 The plane mirror and the hollow pentagonal prism are used for the reflection light path. According to the principle of light reflection, when the plane mirror is deflected by an angle ω, the reflected light will be deflected by 2ω. This plane reflector will increase the difficulty of adjusting the entire optical system. Using a special hollow pentagonal prism, after the incident light is incident, the reflected light is deflected by 90°. When calibrating the entire optical path system, it is only necessary to adjust the incident light to be horizontally incident, and the outgoing light will be emitted vertically upward from the horizontal plane. Ultimately, it is beneficial for the annular light beam to focus in the parabolic reflectors 71, 72. During the entire light beam reflection process, the hollow pentagonal prism only needs to ensure that the incident light can be completely emitted. Compared with the above two optical path steering structures, the hollow pentagonal prism is more conducive to the calibration and adjustment of the optical path system.

[0067] like Figure 6 As shown, the growth process of a single crystal optical fiber using the optical system of the embodiment of the present invention is as follows:

[0068] S1: The laser emitted by the carbon dioxide laser 11 first passes through a beam splitter prism and is split into two beams of light. One beam of light directly passes through a beam expander prism 31 upward for beam expansion, and the other beam of light changes its optical path direction through a plane reflector 41 and then enters a beam expansion system 32.

[0069] S2: The two expanded Gaussian beams are shaped into Bessel annular beams by spatial light modulators 51 and 52.

[0070] S3: The annular beam passes through a hollow pentagonal prism, and after the incident and outgoing beams are deflected by 90°, they are focused to the top of the preformed source rod through a parabolic reflector to form an annular heating area. Laser heating fully melts the preformed source rod to obtain the initial melt for the growth of the crystal fiber, and then the laser hot base method is used to grow the single crystal fiber.

[0071] The operation steps of the laser heating base method include:

[0072] (1) The single crystal optical fiber and the preform source are grown with a diameter reduction ratio of 1:3;

[0073] (2) After the single crystal fiber grows to the required length, the feeding system is turned off, and the pulling device continues to pull the single crystal fiber off, gradually reducing the laser power;

[0074] (3) Turn off the carbon dioxide laser 11, and then take the single crystal optical fiber out of the pulling device to obtain the single crystal optical fiber.

[0075] Figure 7 :Ideal optical path simulation and detector detection of hollow pentagonal prism

[0076] The ideal optical path simulation of a hollow pentagonal prism is as follows Figure 7 As shown in the figure, the laser beam maintains good collimation and spot shape after passing through the prism. The detector detection image shows that the spot is circular and the light intensity distribution is uniform. This result shows that under ideal conditions, the prism can stably transmit the light beam and provide reliable optical path control for the system.

[0077] Figure 8 :Optical path simulation and detector detection of a hollow pentagonal prism rotating 2° clockwise around the x-axis

[0078] When the hollow pentagonal prism is rotated 2° clockwise, the optical path simulation is as follows Figure 8 In the detector detection diagram, the light spot position remains in the center and the light intensity distribution is uniform. The results show that the angle deflection of the hollow pentagonal prism will not affect the shape of the focused light spot, thereby improving the stability of the optical path.

[0079] Fig. 9 :Optical path simulation and detector detection of hollow pentagonal prism rotating 2° counterclockwise around x-axis

[0080] like Fig. 9 As shown in the figure, when the hollow pentagonal prism is rotated 2° counterclockwise, the light spot position remains at the center and the light intensity distribution is uniform. The simulation results further confirm that the hollow pentagonal prism has the effect of improving the stability of the optical path.

[0081] Fig.10 :Ideal optical path simulation and detector detection of plane reflector

[0082] Under ideal conditions, the optical path simulation of the plane reflector is as follows Fig.10 As shown. After the laser beam passes through the reflector, there is no obvious deviation in its transmission path and the beam direction is stable. In the detector detection image, the light spot is located in the center and the light intensity is evenly distributed.

[0083] Fig.11 :Optical path simulation and detector detection of plane reflector rotating 2° counterclockwise

[0084] like Fig.11 As shown in the figure, when the reflector rotates 2° counterclockwise around the x-axis, the reflection angle of the light beam changes significantly. In the detector detection image, the spot position obviously deviates from the design center, the light intensity in some areas is weakened, and the spot shape is slightly deformed. The results show that a small angle change of the reflector will significantly affect the transmission path of the light beam and have a great impact on the growth of single crystal optical fiber.

[0085] Fig.12 :Optical path simulation and detector detection of a plane mirror rotating 2° clockwise around the x-axis

[0086] like Fig.12 As shown in the figure, after the plane reflector rotates 2° clockwise around the x-axis, the optical path deviation direction is opposite to the counterclockwise situation. The detector detection image shows that the light spot deviates from the center, the light intensity distribution is uneven, and the light intensity in some areas is reduced. This phenomenon shows that the angle error of the reflector has a significant impact on the optical path transmission and has a great impact on the growth of single crystal optical fiber.

[0087] pass Figures 7 to 12 The analysis shows that the hollow pentagonal prism can suppress the angle deflection, plays a key role in improving the stability of the optical path, significantly reduces the complexity of the optical path adjustment, and provides an important guiding basis for the design of this system. The above is only a specific implementation of the present invention, but the protection scope of the present invention is not limited to this. Any modification, equivalent substitution and improvement made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A single crystal optical fiber growth device based on a hollow pentagonal prism, characterized in that: The device includes: Carbon dioxide (CO2) laser, as a light source, produces a high-energy laser beam; A beam splitter prism, arranged in the optical path of the carbon dioxide laser, for splitting the laser beam into multiple beams; The beam expansion system is connected after the beam splitting prism and is used to expand the diameter of the laser beam after beam splitting; a plane reflector, arranged in the optical path of the beam expansion system, for changing the propagation direction of the laser beam; Two spatial light adjusters, located on both sides of the plane mirror, are used to adjust the phase and intensity of the laser beam; A self-made hollow pentagonal prism is set on the output optical path of the spatial light debugger to focus the laser beam on the growth area after multiple internal reflections; A parabolic reflector, disposed after the hollow pentagonal prism, is used to further focus and control the direction of the laser beam; The rotary motor system is installed on the base of the growth device and is used to drive the rotation of the single crystal material, thereby achieving uniform growth of the single crystal optical fiber.

2. The single crystal optical fiber growth device according to claim 1, characterized in that: The beam expansion system is composed of a group of lenses, which can be adjusted according to different beam diameter requirements to meet the requirements of different growth speeds and fiber diameters; the rotation speed of the rotary motor system is adjustable, and the growth rate of the single crystal fiber is accurately adjusted by controlling the rotation speed to ensure high-quality crystallization of the fiber.

3. The single crystal optical fiber growth device based on a hollow pentagonal prism as claimed in claim 1, characterized in that: The carbon dioxide laser is used to emit laser, the beam waist diameter of the emitted laser is 2.5 mm, the beam quality is M2<1.25, the central wavelength is 10.6 μm, the average power is 25W-140W, the power stability is <1%, and the laser type is a continuous laser.

4. The single crystal optical fiber growth device based on a hollow pentagonal prism as claimed in claim 1, characterized in that: The lens of the laser beam expander is made of ZnSe material, has an operating wavelength of 10.6 μm, a magnification of 4-8 times, and a maximum light output diameter of 29.4 mm.

5. The single crystal optical fiber growth device based on a hollow pentagonal prism as claimed in claim 1, characterized in that: The plane reflector is made of fused quartz, with gold-plated surface, reflectivity R>99.5%, working wavelength of 10.6 μm, diameter of 25.4 mm, thickness of 3 mm, and incident angle of 45°.

6. The single crystal optical fiber growth device based on hollow pentagonal prism according to claim 1, characterized in that: The spatial light modulator (SLM) is made of ZnSe material and has an operating wavelength of 10.6 μm.

7. The single crystal optical fiber growth device based on hollow pentagonal prism according to claim 1, characterized in that: The specially made hollow pentagonal prism includes two gold-plated working reflection surfaces, one of which is hollow and the crystal source rod can pass through it. The outgoing light beam of the spatial light modulator passes through the first reflection surface to the second reflection surface. The angle between the two reflection surfaces is 45°. When the light is reflected by the two working surfaces, the light beam is deflected by 90°.

8. A method for growing a single crystal optical fiber based on a hollow pentagonal prism as claimed in claims 1 to 7, characterized in that: The method specifically includes: S1: Use a carbon dioxide laser to emit laser light, and split it into two laser beams to form two subsystems; S2: Use a spatial light modulator (SLM) to shape the laser Gaussian beam into a Bessel ring beam; S3: A hollow pentagonal prism is used to achieve a 90° deflection of the light path, and the incoming light beam is reflected and focused to the top of the prefabricated source rod, forming a ring-shaped heating area to achieve the growth of special optical fibers.

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