A pattern homogenizer and its manufacturing method

Abstract

The present invention is applicable to the technical field of optical devices, and provides a mode homogenizer and a manufacturing method. The homogenizer includes: an input optical fiber, a multi-core optical fiber and an output optical fiber. The input optical fiber is a single-core optical fiber. The input optical fiber is coaxially fused with one end of the multi-core optical fiber, and the core of the input optical fiber is aligned with the central core of the multi-core optical fiber, and the other end of the multi-core optical fiber is coaxially fused with the output optical fiber. The present invention proposes a new mode homogenizer manufacturing technology, which can flexibly control the effect of mode homogenization from the design and process, and provides a low-cost, new technical solution for beam homogenization in the field of optical fiber laser processing.

Description

Technical Field

[0001] The invention belongs to the technical field of optical devices, and in particular relates to a pattern homogenizer and a manufacturing method thereof. Background Art

[0002] The field of fiber laser has always been one of the hot spots in optical research, and mode homogenizer, as an important component, has also attracted much attention. The main function of the mode homogenizer is to convert the Gaussian distribution of the input light into a more uniform flat-top beam output to meet the needs of various laser processing fields. The research on mode homogenizers in the field of fiber laser mainly focuses on the following aspects:

[0003] First, the mode homogenizer based on the optical fiber structure. This solution specially designs the core refractive index distribution of the optical fiber to achieve the regulation of the laser mode. The use of mode homogenizing fiber is the current mainstream mode homogenization solution. Since the performance of mode homogenizing fibers from different manufacturers varies greatly, and the length of the mode homogenizing fiber also affects the homogenization effect, the use of mode homogenizing fibers in the industry is not mature and the stability needs to be improved.

[0004] Secondly, the mode homogenizer based on beam shaping. This scheme uses beam shaping devices, such as lens groups, gratings, etc., to adjust the laser beam to make its mode more uniform. For example, the mode can be homogenized through the lens configuration of the lens group and the diffraction effect of the beam.

[0005] In addition, there is a mode homogenizer based on adaptive optics. This solution uses adaptive optical elements, such as deformable mirrors and electro-optic modulators, to adjust the shape of optical elements in real time according to the spatial distribution of input light, making the output light beam pattern more uniform. This method has the advantages of real-time and flexibility.

[0006] In addition, some new research directions of mode homogenizers are emerging, such as mode homogenization based on photonic crystals, etc. These new methods utilize the special properties and structures of materials to achieve the regulation of light with high efficiency and flexibility.

[0007] At present, the research on mode homogenizers in the field of fiber lasers is in a stage of continuous development and exploration. With the advancement of science and technology and the deepening of research, the application of mode homogenizers in fiber laser systems is gradually increasing, bringing more possibilities for the development of fiber laser technology. Overall, the current production scheme of mode homogenizers still has the problems of high cost and difficulty. Summary of the invention

[0008] In view of the above problems, the purpose of the present invention is to provide a pattern homogenizer and a method for manufacturing the same, which is a brand-new manufacturing method and aims to solve the technical problems of high cost and great difficulty of existing solutions.

[0009] The present invention adopts the following technical solution:

[0010] The mode homogenizer comprises an input optical fiber, a multi-core optical fiber and an output optical fiber. The input optical fiber is a single-core optical fiber. The input optical fiber is coaxially fused with one end of the multi-core optical fiber, and the core of the input optical fiber is aligned with the central core of the multi-core optical fiber. The other end of the multi-core optical fiber is coaxially fused with the output optical fiber, and the core diameter of the output optical fiber is not less than the total diameter formed by all the cores in the multi-core optical fiber. The middle part of the multi-core optical fiber is tapered to form a straight area.

[0011] Furthermore, the multi-core optical fiber has seven cores, one core in the center and six cores evenly distributed outside, and there is no crosstalk between the cores.

[0012] Furthermore, the preparation method comprises the following steps:

[0013] Step S1, preparing input optical fiber, multi-core optical fiber and output optical fiber;

[0014] Step S2, using a cutting knife to flatten the end faces of the input optical fiber and one end of the multi-core optical fiber, and then aligning and coaxially splicing them, and before splicing, ensuring that the core of the input optical fiber is aligned with the central core of the multi-core optical fiber;

[0015] Step S3, using a cutting knife to cut the end faces of the other end of the multi-core optical fiber and one end of the output optical fiber flat, and then aligning and welding them using a cladding alignment method;

[0016] Step S4, placing the combined optical fiber after fusion on a taper drawing machine to prepare for taper drawing, and adjusting the position so that the taper drawing machine clamps the input optical fiber and the output optical fiber respectively;

[0017] Step S5, connect the input end of the input optical fiber to the laser, connect the output end of the output optical fiber to the spot detector, start the taper program, monitor the spot shape displayed by the spot detector, and stop tapering until the ideal homogenized spot is reached, so as to obtain a mode homogenizer.

[0018] Furthermore, the preparation method further comprises the following steps:

[0019] Step S6: fix the pattern homogenizer on the packaging substrate by glue dispensing to complete the packaging.

[0020] The beneficial effects of the present invention are as follows: the present invention designs a mode homogenizer based on the mode coupling effect of a multi-core optical fiber, the mode homogenizer manufacturing scheme is simple in process, the manufacturing requires conventional optical fiber processing technologies such as cutting, welding, and tapering, and the manufactured devices are all full-fiber devices, the structure is stable and reliable, and the cost is much lower than the existing design scheme. Moreover, by adjusting the parameters of the tapering, the degree of optical coupling can be flexibly changed, thereby flexibly controlling the effect of mode homogenization. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of a homogenizer before taper drawing in a manufacturing mode provided by an embodiment of the present invention;

[0022] Figure 2 It is a schematic diagram of the structure of the homogenizer after taper of the manufacturing mode provided by the embodiment of the present invention;

[0023] Figure 3 It is a cross-sectional schematic diagram of the relative position and shape of the fiber core after tapering;

[0024] Figure 4 It is the core power intensity distribution diagram in multi-core optical fiber;

[0025] Figure 5 This is a graph showing the core power ratio in a multi-core optical fiber. DETAILED DESCRIPTION

[0026] 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 accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0027] In order to illustrate the technical solution of the present invention, a specific embodiment is provided below for illustration.

[0028] First, Figure 1 , 2 As shown, this embodiment provides a mode homogenizer, including an input optical fiber 1, a multi-core optical fiber 3 and an output optical fiber 5, wherein the input optical fiber 1 is a single-core optical fiber, the input optical fiber 1 is coaxially fused with one end of the multi-core optical fiber 3, and ensures that the input optical fiber core 2 is aligned with the central core 4 of the multi-core optical fiber 3, the other end of the multi-core optical fiber 3 is coaxially fused with the output optical fiber 5, and the diameter of the output optical fiber core 6 is not less than the total diameter formed by all the cores in the multi-core optical fiber, and the middle part of the multi-core optical fiber 3 is tapered to form a straight area 7.

[0029] In this structure, the input optical fiber 1 of the mode homogenizer is a conventional single-core optical fiber, and there are multiple cores inside the multi-core optical fiber, of which the central one is the central core and the outer circle is the outer core. As an example, in this embodiment, the multi-core optical fiber 2 has seven cores, one core in the center and six cores evenly distributed on the outer sides. Each core can guide light independently, and there is no crosstalk between the cores. The output optical fiber of the mode homogenizer generally has a larger core. The two ends of the multi-core optical fiber are fused with the input optical fiber and the output optical fiber respectively, and then the middle multi-core optical fiber is tapered. Of course, in the present invention, the multi-core optical fiber is not limited to a seven-core optical fiber.

[0030] After the multi-core optical fiber is tapered at high temperature, the tapering forms a straight area, this area becomes thinner, the distance between the cores becomes shorter, and the mode fields of each core overlap. According to the mode coupling theory, the laser beam is introduced from the input optical fiber, and then along the input optical fiber core, after the light beam is injected into the central core of the multi-core optical fiber, part of the energy of the light in this area will gradually couple to the peripheral core for transmission. The intensity of the coupling of the central light to the periphery can be flexibly adjusted by the length and diameter of the tapered area. After leaving this area, the single beam of light will become multiple beams of light and transmit into the core of the output optical fiber. At this time, the energy of the beam will fill the core of the output optical fiber more evenly, thereby achieving the effect of beam homogenization.

[0031] Therefore, the mode homogenizer of the present invention utilizes the mode coupling after tapering of the multi-core optical fiber to split an input laser beam into multiple laser beams entering the output optical fiber, so that the laser is evenly dispersed in the core of the output optical fiber, thereby achieving the purpose of homogenizing the output light beam.

[0032] In addition, based on the above-mentioned model homogenizer, this embodiment also provides a specific preparation method, comprising the following steps:

[0033] Step S1, preparing input optical fiber, multi-core optical fiber and output optical fiber.

[0034] Take the common 14 / 250-100 / 120 / 360 mode homogenizer (parameter unit is micron, the same below) as an example. Prepare a conventional 14 / 250 single-core optical fiber with a core of 14μm and a cladding of 250μm. It is mainly connected to the 14 / 250 output laser, and the laser is transmitted through the 14μm core. The multi-core optical fiber is a seven-core optical fiber with a cladding diameter of 250μm. There is a central core in the center of the cladding. Six peripheral cores of the same diameter are evenly and equidistantly arranged around the central core. The diameters are all 14μm. A total of 7 cores are arranged in a regular hexagon, and the center distance between each core is 25μm. The output optical fiber is a 50 / 70 / 360 optical fiber (50 / 70 / 360 are the core / cladding / coating diameters, respectively).

[0035] Step S2: Use a cutting knife to cut the end faces of the input optical fiber and one end of the multi-core optical fiber flat, and then align and coaxially weld them. Before welding, ensure that the core of the input optical fiber is aligned with the central core of the multi-core fiber.

[0036] Use a cleaver to cut the end faces of the input optical fiber and one end of the multi-core optical fiber respectively, and align and fuse them so that the two optical fibers are fused into one optical fiber, and ensure that the core of the input optical fiber is aligned with the central core of the multi-core fiber.

[0037] Step S3: Use a cutting knife to flatten the end faces of the other end of the multi-core optical fiber and one end of the output optical fiber, and then perform alignment and fusion splicing using a cladding alignment method.

[0038] Cut the output optical fiber, i.e. 50 / 70 / 360 optical fiber, and the other end of the multi-core optical fiber flat and align and fuse them into one optical fiber. The cladding is aligned during the fusion. Figure 1 shown.

[0039] Step S4, placing the combined optical fiber after fusion on a taper drawing machine to prepare for taper drawing, and after adjusting the position, the taper drawing machine clamps the input optical fiber and the output optical fiber respectively.

[0040] The combined optical fiber obtained by the above two fusion splicings is placed on a taper machine. The taper machine clamps the input optical fiber and the output optical fiber respectively, and the clamping position is adjusted so that the multi-core optical fiber is located in the middle of the taper machine torch.

[0041] Step S5, connect the input end of the input optical fiber to the laser, connect the output end of the output optical fiber to the spot detector, start the taper program, monitor the spot shape displayed by the spot detector, and stop tapering until the ideal homogenized spot is reached, so as to obtain a mode homogenizer.

[0042] Connect the input fiber to the laser and the output fiber to the spot detector. Start the taper program and use the taper machine to thin the middle of the multi-core fiber. Monitor the spot shape displayed by the spot detector at the same time. Stop tapering until the ideal homogenized spot is reached. The cross-sectional diagram of the relative position and shape of the fiber core after tapering is shown in the figure below. Figure 3 As shown in the figure, the center is the central core and the two sides are the peripheral cores. After the taper, the taper position of the multi-core optical fiber becomes thinner, and all the cores become thinner at the same time. The core distance of the multi-core optical fiber is also significantly reduced, achieving the conditions for optical coupling. When the light from the central optical fiber passes through this area, it will gradually couple to the outer peripheral cores until the light energy is evenly distributed in the central core and the surrounding peripheral cores. The power intensity distribution diagram in the multi-core optical fiber is shown in the figure below. Figure 4 shown.

[0043] Figure 4 In the example, the initial condition is to inject laser into the central core, and the laser power intensity of the incident laser is set to 100%. At this time, the power intensity of the outer cores on both sides is 0; when the laser passes through the thinning area, it will gradually couple to the cores on both sides as the transmission distance increases, and the power intensity of the central core will gradually decrease ( Figure 5 The light intensity of the outer cores on both sides will gradually increase ( Figure 5 The green and red lines in the middle show that at the end of the tapered area, the power of the central core and the peripheral core is exactly equal. After the tapered area, the distance between the cores becomes larger, and optical coupling cannot occur between them, so the power distribution in the center and the periphery continues to be maintained. Finally, a beam of light is evenly divided into multiple beams of light and injected into the output fiber, achieving a mode homogenization effect.

[0044] Step S6: fix the pattern homogenizer on the packaging substrate by glue dispensing to complete the packaging.

[0045] After the tapering is completed, the combined optical fiber after tapering is removed from the tapering machine, fixed on a suitable packaging substrate and fixed by glue, and the final mode homogenizer is obtained after the packaging is completed.

[0046] In summary, the present invention provides a new manufacturing process for a mode homogenizer, which is completely different from the existing process. It utilizes the mode coupling after tapering of the multi-core optical fiber to split an input laser beam into multiple laser beams entering the output optical fiber, so that the laser is evenly dispersed in the core of the output optical fiber, thereby achieving the purpose of homogenizing the output light beam.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a pattern homogenizer, characterized in that: The mode homogenizer comprises an input optical fiber, a multi-core optical fiber and an output optical fiber, wherein the input optical fiber is a single-core optical fiber, the input optical fiber is coaxially fused with one end of the multi-core optical fiber, and the core of the input optical fiber is aligned with the central core of the multi-core optical fiber, the other end of the multi-core optical fiber is coaxially fused with the output optical fiber, and the core diameter of the output optical fiber is not less than the total diameter formed by all the cores in the multi-core optical fiber, and the middle part of the multi-core optical fiber is tapered to form a straight area; the preparation method comprises the following steps: Step S1, preparing input optical fiber, multi-core optical fiber and output optical fiber; Step S2, using a cutting knife to flatten the end faces of the input optical fiber and one end of the multi-core optical fiber, and then aligning and coaxially splicing them, and before splicing, ensuring that the core of the input optical fiber is aligned with the central core of the multi-core optical fiber; Step S3, using a cutting knife to cut the end faces of the other end of the multi-core optical fiber and one end of the output optical fiber flat, and then aligning and welding them using a cladding alignment method; Step S4, placing the combined optical fiber after fusion on a taper drawing machine to prepare for taper drawing, and adjusting the position so that the taper drawing machine clamps the input optical fiber and the output optical fiber respectively; Step S5, connecting the input end of the input optical fiber to the laser, connecting the output end of the output optical fiber to the spot detector, starting the taper program, and monitoring the spot shape displayed by the spot detector. After the taper is pulled until the ideal homogenized spot is reached, the taper is stopped, and a mode homogenizer can be obtained; After the tapering, the tapering position of the multi-core optical fiber becomes thinner, and all the cores of the multi-core optical fiber become thinner at the same time. The core distance of the multi-core optical fiber is also significantly reduced, meeting the conditions for optical coupling. When the light of the central optical fiber passes through this area, it will gradually couple to the outer peripheral cores until the light energy is evenly distributed in the central core and the surrounding peripheral cores.

2. The method for preparing the pattern homogenizer according to claim 1, characterized in that: The preparation method further comprises the following steps: Step S6: fix the pattern homogenizer on the packaging substrate by glue dispensing to complete the packaging.

3. The method for preparing the pattern homogenizer according to claim 2, characterized in that: The multi-core optical fiber has seven fiber cores, one fiber core in the center and six fiber cores around the outside are evenly distributed, and there is no crosstalk between the fiber cores.

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