Manufacturing method of mode scrambler, mode scrambler and laser system

Abstract

The invention discloses a manufacturing method of a mode scrambler, the mode scrambler and a laser system. The manufacturing method comprises the following steps: step 1, placing a section of multimode optical fiber on an optical fiber rotating clamp; 2, performing etching in the fiber core of the multimode fiber by using femtosecond laser to form dot marks or line marks; and step 3, adjusting the spatial position of the multimode optical fiber to enable a plurality of point marks and / or line marks to be etched and distributed in the fiber core of the multimode optical fiber so as to change the refractive index distribution of the fiber core of the multimode optical fiber. The manufacturing method has the advantages of being easy to operate, good in repeatability, low in cost and the like, and the mode scrambler manufactured through the manufacturing method is simple in structure, higher in reliability and better in integrity.

Description

Technical Field

[0001] The invention belongs to the technical field of optical fiber lasers, and in particular relates to a method for manufacturing a mode scrambler, a mode scrambler and a laser system. Background Art

[0002] Fiber lasers are greatly welcomed and developed in the industrial market due to their compact structure, high stability, and flexible laser transmission. However, different industrial processing application scenarios have different requirements for the characteristic parameters of fiber lasers. For example, in cutting applications, cutting equipment requires fiber lasers with high beam quality to increase the cutting speed, while in welding applications, the beam energy output by high beam quality fiber lasers is too concentrated, resulting in a small tolerance for weld assembly gaps, which is not suitable for special joints that require a larger fusion width. At the same time, the welding process is more complicated in laser deep fusion welding, and excessive evaporation in local areas can easily cause keyhole collapse and violent fluctuations in the molten pool, resulting in poor weld formation quality and easy generation of porosity defects. Against this market demand background, mode disruptors were invented and applied to fiber lasers.

[0003] At present, there are two types of existing mode scramblers: one type of mode scrambler is formed by staggered fusion of single-mode fiber and multi-mode fiber, which changes the incident angle of the multi-mode fiber into which the light in the single-mode fiber enters through staggered fusion, thereby exciting the high-order mode in the fiber; although this mode scrambler has the advantages of small size, simple production, low cost, and stable mode, it will cause laser energy loss due to its preparation through staggered fusion, and the leakage of laser will easily cause the fusion point to burn, and the reliability is low. The other type of mode scrambler is formed by mechanically squeezing the transmission fiber, which makes the internal modes of the fiber couple with each other, thereby controlling the mode of the fiber output laser, that is, changing the beam quality; this mode scrambler has a complex structure, relies on high-precision adjustment of the mechanical mechanism, and has high requirements on the precision of the mechanical device, making it costly. Summary of the invention

[0004] In view of the above problems, the present invention discloses a method for manufacturing a mode scrambler, a mode scrambler and a laser system to overcome the above problems or at least partially solve the above problems.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] One aspect of the present invention discloses a method for manufacturing a mode scrambler, the method comprising the following steps:

[0007] Step 1, placing a section of multimode optical fiber on an optical fiber rotating fixture;

[0008] Step 2, using a femtosecond laser to etch into the core of the multimode optical fiber to form a dot mark or a line mark;

[0009] Step 3, adjusting the spatial position of the multimode optical fiber so that a plurality of the point marks and / or the line marks are etched and distributed in the core of the multimode optical fiber to change the refractive index distribution of the core of the multimode optical fiber.

[0010] Furthermore, the step 2 is specifically as follows:

[0011] Focusing a femtosecond laser with a wavelength of 515 nm on the core of the multimode optical fiber through a first reflector, a second reflector, a galvanometer, and a short-focus lens in sequence, and etching a dot mark or a line mark in the core of the multimode optical fiber;

[0012] Wherein, the galvanometer and the short-focus lens are arranged on a displacement frame, and the displacement frame can move horizontally along the direction of the output light beam of the short-focus lens.

[0013] Furthermore, the step 3 also includes:

[0014] The direction of the etching line mark is controlled by moving the displacement frame and swinging the galvanometer.

[0015] Further, the adjusting the spatial position of the multimode optical fiber is specifically:

[0016] The rotation angle of the multimode optical fiber is adjusted by rotating the optical fiber rotating fixture; and the axial displacement of the multimode optical fiber is adjusted by moving the moving platform below the optical fiber rotating fixture.

[0017] Furthermore, the manufacturing method further comprises:

[0018] Step 4, adjusting the short-focus lens so that the femtosecond laser is focused on the cladding of the multimode optical fiber, etching on the outer circumference of the cladding of the multimode optical fiber to form a roughened section with destroyed total reflection characteristics, and burning to form multiple cavities in the cladding of the multimode optical fiber.

[0019] Another aspect of the present invention discloses a mode scrambler, which is manufactured by the method for manufacturing a mode scrambler described above.

[0020] Furthermore, the axial length of the mode scrambler is 8 cm to 12 cm.

[0021] Another aspect of the present invention discloses a laser system, comprising a fiber laser and the above-mentioned mode scrambler;

[0022] The mode scrambler is arranged at the output end of the optical fiber laser.

[0023] The advantages and beneficial effects of the present invention are:

[0024] In the method for manufacturing the mode scrambler of the present invention, a plurality of dot marks and / or line marks are etched in the optical fiber core by a femtosecond laser to change the refractive index distribution of the optical fiber core, thereby realizing the coupling of the core transmission laser mode, and the method has the advantages of simple operation, good repeatability, low cost, etc.; and the mode scrambler manufactured by the manufacturing method has a simple structure, higher reliability, and better integrity. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0026] Figure 1 FIG. 1 is a diagram showing the implementation steps of a method for manufacturing a mode scrambler in one embodiment of the present invention;

[0027] Figure 2 It is a structural diagram of a femtosecond laser writing device in one embodiment of the present invention.

[0028] In the figure: 1. Femtosecond laser; 2. First reflector; 3. Second reflector; 4. Vibration mirror; 5. Short-focus lens; 6. Displacement frame; 7. Optical fiber rotation fixture; 8. Multimode optical fiber. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] The technical solutions provided by various embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0031] In one embodiment of the present invention, a method for manufacturing a mode scrambler is provided. Figure 1 As shown, the production method comprises the following steps:

[0032] Step 1: Place a section of multimode optical fiber on the optical fiber rotation fixture.

[0033] Wherein, a section of multimode optical fiber may be an optical fiber having a coating layer, such as Figure 2 As shown, the multimode optical fiber 8 is clamped on the optical fiber rotation clamp 7 along the axial direction, and the optical fiber rotation clamp 7 allows the multimode optical fiber 8 to rotate circumferentially.

[0034] Step 2: using a femtosecond laser to etch into the core of the multimode optical fiber to form dot marks or line marks.

[0035] Among them, the femtosecond laser can pass through the coating and cladding of the multimode optical fiber and focus on the core of the multimode optical fiber. By controlling the output power of the femtosecond laser, the femtosecond laser etches into point marks or line marks in the core of the multimode optical fiber, and the coating and cladding of the multimode optical fiber will not be damaged during the etching process, thus ensuring the structural integrity of the multimode optical fiber.

[0036] Step 3, adjusting the spatial position of the multimode optical fiber so that a plurality of point marks and / or line marks are etched and distributed in the core of the multimode optical fiber to change the refractive index distribution of the core of the multimode optical fiber, thereby forming a mode scrambler.

[0037] After etching a certain area of ​​the fiber core to form dots or lines, the spatial position of the multimode optical fiber is adjusted so that the femtosecond laser forms dots or lines in other areas of the fiber core, thereby distributing multiple dots and / or lines in the core of the multimode optical fiber.

[0038] In summary, in the method for manufacturing the mode scrambler of the present embodiment, a plurality of dot marks and / or line marks are etched in the optical fiber core by a femtosecond laser to change the refractive index distribution of the optical fiber core, thereby realizing the coupling of the core transmission laser mode, which has the advantages of simple operation, good repeatability, and low cost; and the mode scrambler manufactured by this manufacturing method has a simple structure, higher reliability, and better integrity.

[0039] In this embodiment, step 2 is specifically as follows:

[0040] like Figure 2 As shown, the femtosecond laser with a wavelength of 515 nm output by the femtosecond laser 1 is focused on the core of the multimode optical fiber 8 through the first reflector 2, the second reflector 3, the galvanometer 4 and the short-focus lens 5 in sequence, and point marks or line marks are etched in the core of the multimode optical fiber 8, thereby achieving precise control of the femtosecond laser.

[0041] Among them, the galvanometer 4 and the short-focus lens 5 are arranged on a displacement frame 6, and the displacement frame 6 can move horizontally along the direction of the output light beam of the short-focus lens 5. The displacement frame 6 moves horizontally, driving the galvanometer 4 and the short-focus lens 5 to move horizontally, so that the short-focus lens 5 can focus on different positions in the core of the multi-mode optical fiber 8.

[0042] Furthermore, step 3 further includes:

[0043] By moving the displacement frame and swinging the galvanometer, the direction of the etching line marks can be controlled to achieve precise control of the refractive index of the optical fiber core.

[0044] In addition, the spatial position of the multimode optical fiber is adjusted as follows:

[0045] The rotation angle of the multimode optical fiber is adjusted by rotating the optical fiber rotating fixture, and the optical fiber rotating fixture is fixed on a moving platform; the axial displacement of the multimode optical fiber is adjusted by moving the moving platform below the optical fiber rotating fixture; in this way, multiple point marks and / or line marks are distributed in the core of the multimode optical fiber, thereby realizing the regulation of the refractive index of the optical fiber core.

[0046] In other embodiments, the method for manufacturing the mode scrambler further includes:

[0047] Step 4, adjust the short-focus lens to focus the femtosecond laser on the cladding of the multimode optical fiber, and etch a roughened section with destroyed total reflection characteristics on the outer circumference of the cladding of the multimode optical fiber to form a cladding light filter, so that the cladding light is emitted from the cladding at the roughened section to achieve cladding light stripping. The setting of the roughened section does not destroy the overall structure of the cladding of the multimode optical fiber, so that the cladding of the multimode optical fiber still has good mechanical properties. The roughened section is etched on the section of multimode optical fiber by a femtosecond laser, so that the section of multimode optical fiber has both cladding light stripping and mode scrambling functions.

[0048] In addition, the femtosecond laser burns into multiple cavities in the cladding of the multimode optical fiber; in this way, a part of the cladding light transmitted in the cladding of the multimode optical fiber will be emitted through the roughened section when reflected to the roughened section, thereby achieving the stripping of the cladding light; another part of the cladding light transmitted in the cladding of the multimode optical fiber will be scattered when it is emitted to the cavity, and the generated scattered light will be emitted through the roughened section, thereby achieving the stripping of the cladding light, thereby making the stripping degree of the cladding light higher. Moreover, by setting the cavity, the required axial length of the roughened section can be reduced, thereby making the volume of the cladding light filter smaller. Similarly, the setting of the cavity does not destroy the overall structure of the cladding, so that the cladding still has good mechanical properties.

[0049] The sizes of the multiple cavities are different, so that the cladding light in the cladding of the multimode optical fiber is scattered at different angles through different cavities, thereby making the scattered light have a larger scattering range, so that the scattered light generated by the cladding light can be better emitted through the roughened area, so that the stripping effect of the cladding light is better. The multiple cavities are spaced at different distances in the axial direction of the cladding, so that the cladding light with different reflection angles in the cladding of the multimode optical fiber can be scattered and stripped, thereby improving the stripping degree of the cladding light.

[0050] Another embodiment of the present invention provides a mode scrambler, which is manufactured by the method for manufacturing the mode scrambler in the above embodiment, wherein the axial length of the mode scrambler is 8 cm to 12 cm.

[0051] The mode scrambler has the advantages of simple structure, higher reliability, better integrity, etc.

[0052] The above scrambler is tested, and the test structure is as follows:

[0053] The power of the beam input to the mode scrambler is 434 W, and the output power of the beam after passing through the mode scrambler is 425.5 W, with an efficiency of 98.04%, an insertion loss of 0.086 dB, a beam quality reduction of 19.66%, and a beam divergence increase of 7.62%.

[0054] In yet another embodiment of the present invention, a laser system is provided. The laser system includes a fiber laser and the mode scrambler in the above embodiment.

[0055] Specifically, the mode scrambler is arranged at the output end of the optical fiber laser.

[0056] The laser system has better output beam uniformity.

[0057] The above is only a specific embodiment of the present invention. Under the above teachings of the present invention, those skilled in the art can make other improvements or modifications on the basis of the above embodiments. Those skilled in the art should understand that the above specific description is only to better explain the purpose of the present invention, and the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for manufacturing a mode scrambler, characterized in that: The production method comprises the following steps: Step 1, placing a section of multimode optical fiber on an optical fiber rotating fixture; Step 2, using a femtosecond laser to etch into the core of the multimode optical fiber to form a dot mark or a line mark; Step 3, adjusting the spatial position of the multimode optical fiber so that a plurality of the point marks and / or the line marks are etched and distributed in the core of the multimode optical fiber to change the refractive index distribution of the core of the multimode optical fiber.

2. The method for manufacturing a mode scrambler according to claim 1, characterized in that: The step 2 is specifically as follows: Focusing a femtosecond laser with a wavelength of 515 nm on the core of the multimode optical fiber through a first reflector, a second reflector, a galvanometer, and a short-focus lens in sequence, and etching a dot mark or a line mark in the core of the multimode optical fiber; Wherein, the galvanometer and the short-focus lens are arranged on a displacement frame, and the displacement frame can move horizontally along the direction of the output light beam of the short-focus lens.

3. The method for manufacturing a mode scrambler according to claim 2, characterized in that: The step 3 also includes: The direction of the etching line mark is controlled by moving the displacement frame and swinging the galvanometer.

4. The method for manufacturing a mode scrambler according to claim 1, characterized in that: The adjusting of the spatial position of the multimode optical fiber is specifically as follows: The rotation angle of the multimode optical fiber is adjusted by rotating the optical fiber rotating fixture; and the axial displacement of the multimode optical fiber is adjusted by moving the moving platform below the optical fiber rotating fixture.

5. The method for manufacturing a mode scrambler according to claim 2, characterized in that: The production method further comprises: Step 4, adjusting the short-focus lens so that the femtosecond laser is focused on the cladding of the multimode optical fiber, etching on the outer circumference of the cladding of the multimode optical fiber to form a roughened section with destroyed total reflection characteristics, and burning to form multiple cavities in the cladding of the multimode optical fiber.

6. A mode scrambler, characterized in that: The mode scrambler is manufactured by the method for manufacturing a mode scrambler according to any one of claims 1 to 4.

7. The mode scrambler according to claim 6, characterized in that The axial length of the mode scrambler is 8 cm to 12 cm.

8. A laser system, characterized in that: comprising a fiber laser and the mode scrambler as claimed in claim 6; The mode scrambler is arranged at the output end of the optical fiber laser.

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