Laser shaping device based on output end face of microstructure optical fiber

Abstract

The invention discloses a laser shaping device based on a microstructure optical fiber output end face, and relates to the technical field of laser shaping, the laser shaping device based on the microstructure optical fiber output end face comprises an optical fiber, the optical fiber is sequentially provided with an input end face, a transmission section and an output end face, the input end face is used for being fixedly connected with a laser generator, and the transmission section is used for being fixedly connected with the output end face. The transmission section is arranged on the input end face and receives laser beams emitted by the laser generator, the transmission section can transmit the laser beams on the input end face to the output end face, the output end face is provided with a plurality of microstructure units, and all the microstructure units can cooperatively regulate and control light intensity distribution and / or light spot shapes of the laser beams; the laser shaping device based on the output end face of the microstructure optical fiber is simple in structure, high in integration level, efficient and low in loss.

Description

Technical Field

[0001] The present invention relates to the technical field of laser shaping, and in particular to a laser shaping device based on a microstructured optical fiber output end face. Background Art

[0002] In industrial laser manufacturing, Gaussian-like laser beams are often converted into flat-top beams. Flat-top beams are characterized by uniform energy at the top and a very sharp boundary. Specifically, the "transition zone" is short, and the steep curve from 90% to 10% of the laser energy across the beam creates a distinct laser boundary, clearly distinguishing the laser-processed area from the unprocessed area. Therefore, flat-top beams are ideal for various laser processing applications, achieving high efficiency and precision.

[0003] In traditional laser shaping technology, external optical elements such as spatial light modulators (SLMs), diffractive optical elements (DOEs), lens groups, or reflectors are usually used to control the laser beam to achieve uniform light intensity distribution (such as converting a Gaussian beam into a flat-top beam) or transform the spot shape (such as converting a circular spot into a square or linear spot). However, there are the following limitations:

[0004] 1. Complex system: Multiple sets of optical components are required, resulting in a large optical path structure, high difficulty in adjustment, and strict requirements on the installation and adjustment accuracy of optical devices;

[0005] 2. High energy loss: When a light beam passes through multiple optical interfaces, it is easy to cause multiple energy losses due to reflection, scattering or absorption;

[0006] 3. Low integration: External optical components are difficult to integrate compactly with fiber optic systems, which limits the development of miniaturized and portable devices.

[0007] Therefore, there is an urgent need for a laser shaping device with a simple structure and high efficiency integration to overcome the shortcomings of the existing technology. Summary of the Invention

[0008] The purpose of the present invention is to provide a laser shaping device based on the output end face of a microstructured optical fiber to solve the problems existing in the above-mentioned prior art, with a simple structure, high integration, high efficiency and low loss.

[0009] To achieve the above object, the present invention provides the following solutions:

[0010] The present invention provides a laser shaping device based on a microstructured optical fiber output end face, comprising an optical fiber, wherein the optical fiber sequentially has an input end face, a transmission section, and an output end face. The input end face is used to be fixedly connected to a laser generator and receive a laser beam emitted by the laser generator. The transmission section can transmit the laser beam on the input end face to the output end face. The output end face has a plurality of microstructure units, all of which can collaboratively regulate the light intensity distribution and / or spot shape of the laser beam.

[0011] Preferably, all the microstructure units are arranged side by side at intervals on the output end face, one end of the microstructure unit is a wide end, and the other end of the microstructure unit is a narrow end, the wide end is placed between the transmission section and the narrow end, and the microstructure unit gradually narrows from the wide end to the narrow end along the two oblique side surfaces on the microstructure unit, the angle between the two oblique side surfaces on the microstructure unit is 5° to 160°, the maximum width of the wide end is 1μm to 1300μm, and the distance between the narrow end and the wide end is 0.1μm to 650μm; the distance between any two adjacent microstructure units is 1μm to 650μm; the angle between the center line of the microstructure unit and the center line of the transmission section is 0° to 45°.

[0012] Preferably, all the microstructure units are evenly distributed on the output end surface, the microstructure units are two-dimensional structures, and the surface height of the microstructure units is:

[0013]

[0014] Wherein, z(x) is the surface height, c=1 / R is the curvature, R is the base circle radius, k is the cone constant, and a4, a6, ... are higher-order coefficients used to correct higher-order aberrations and optimize light intensity uniformity.

[0015] Preferably, all the microstructure units are evenly distributed on the output end surface, the microstructure units are three-dimensional structures, and the surface height of the microstructure units is:

[0016]

[0017] Wherein, z(x, y) is the surface height, c=1 / R is the curvature, R is the base circle radius, k is the cone constant, and a4, a6... are high-order coefficients used to correct high-order aberrations and optimize light intensity uniformity.

[0018] Preferably, a nano grating is fixedly provided on the surface of the microstructure unit, and the period of the nano grating is less than 1 / 2 of the wavelength of the incident light; the groove depth of the nano grating is 200nm to 500nm, and the groove width is 100nm to 300nm.

[0019] Preferably, a first anti-reflection coating is fixedly provided on the outer surface of the microstructure unit, and the refractive index of the first anti-reflection coating gradually changes from 1.8 to 1.2 from the outer surface of the microstructure unit to the outside; a second anti-reflection coating is fixedly provided on the inner surface of the microstructure unit, and the refractive index of the first anti-reflection coating gradually decreases from 1.5 to 1.1 from the inner surface of the microstructure unit to the inside.

[0020] Preferably, the surfaces of any two adjacent microstructure units are transitionally connected via a wedge-shaped transition structure; the width of the wedge-shaped transition structure is 2 μm-20 μm, and the inclination angle is 5° to 30°.

[0021] Preferably, the microstructure unit is square, circular, hemispherical, spherical, pyramidal, multi-stepped or parabolic.

[0022] Preferably, the optical fiber has a graded refractive index optical fiber segment, which is placed between the transmission segment and the output end face. The graded refractive index optical fiber segment can convert the laser beam transmitted by the transmission segment into a collimated laser beam and transmit the collimated laser beam to the output end face.

[0023] Preferably, the microstructure unit is made by picosecond or femtosecond laser writing with a pulse energy of 0.1 μJ to 1 mJ and a repetition frequency of 10 KHz to 200 MHz.

[0024] Compared with the prior art, the present invention has achieved the following technical effects:

[0025] The laser shaping device based on the output end face of a microstructured optical fiber provided by the present invention has a plurality of microstructure units arranged on the output end face, and the light intensity distribution and / or spot shape of the laser beam are synergistically regulated by all the microstructure units, and the output spot characteristics are directly regulated by all the microstructure units, without the need for additional spatial light path modulators, diffraction optical elements or complex lens groups, which greatly reduces the number of optical elements, makes the system structure more compact, and is easy to integrate into miniaturized and portable devices, with a simple structure and high integration. After the laser is transmitted inside the optical fiber, it is directly modulated and output by all the microstructure units, avoiding the energy loss such as reflection and scattering caused by traditional optical interfaces, improving the utilization rate of light energy, and achieving high efficiency and low loss. All microstructure units The structural unit can adopt a specific periodic or non-periodic arrangement design based on the actual laser output requirements, combine phase modulation and diffraction effects, and use the interference and diffraction principles to reconstruct the light field distribution, realize light intensity conversion or light spot conversion, and realize the regulation of light intensity distribution and / or light spot shape to adapt to the needs of different application scenarios; the integrated structure of laser transmission and modulation of optical fiber avoids the influence of the installation deviation of traditional external optical components on the beam quality, and the output light field is more stable, which is suitable for high-precision fields such as industrial processing and medical surgery. Therefore, the laser shaping device based on the output end face of the microstructured optical fiber provided by the present invention realizes the lightweight and high efficiency of the beam shaping technology, and solves the core technical defects of the existing technology such as complex system and high loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 A schematic structural diagram of a laser shaping device based on a microstructured optical fiber output end face provided by the present invention;

[0028] Figure 2 for Figure 1 Schematic diagram of setting a microstructure unit on the output end surface;

[0029] Figure 3 for Figure 2 cross-section of the structure;

[0030] Figure 4 for Figure 1 A schematic diagram of a case where multiple microstructure units are arranged side by side on the output end surface;

[0031] Figure 5 for Figure 4 A top view of the structure;

[0032] Figure 6 for Figure 4 cross-section of the structure;

[0033] In the figure: 10-optical fiber, 101-input end face, 102-transmission segment, 103-output end face, 104-graded refractive index optical fiber segment, 20-microstructure unit, 201-oblique side surface, 202-wedge-shaped transition structure. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying 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 making creative efforts are within the scope of protection of the present invention.

[0035] The purpose of the present invention is to provide a laser shaping device based on the output end face of a microstructured optical fiber to solve the problems existing in the above-mentioned prior art, with a simple structure, high integration, high efficiency and low loss.

[0036] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] like Figures 1 to 6 As shown, the present invention provides a laser shaping device based on a microstructured optical fiber output end face, comprising an optical fiber 10, which sequentially has an input end face 101, a transmission segment 102, and an output end face 103. The input end face 101 is used to be fixedly connected to a laser generator and receive a laser beam emitted by the laser generator. The transmission segment 102 can transmit the laser beam on the input end face 101 to the output end face 103. The output end face 103 has a plurality of microstructure units 20, and all of the microstructure units 20 can collaboratively control the light intensity distribution and / or spot shape of the laser beam.

[0038] The laser shaping device based on the output end face of a microstructured optical fiber provided by the present invention has a plurality of microstructure units 20 arranged on the output end face 103. The light intensity distribution and / or spot shape of the laser beam are coordinated and regulated by all the microstructure units 20. The output spot characteristics are directly regulated by all the microstructure units 20. There is no need to add an additional spatial light path modulator, diffraction optical element or complex lens group, which greatly reduces the number of optical elements, makes the system structure more compact, and is easy to be integrated into miniaturized and portable devices. The structure is simple and the integration is high. After the laser is transmitted inside the optical fiber 10, it is directly output by the optical fiber 10. The microstructure unit 20 modulates the output, avoiding the energy loss such as reflection and scattering caused by the traditional optical interface, improving the utilization rate of light energy, and achieving high efficiency and low loss. All microstructure units 20 can adopt specific periodic or non-periodic arrangement design according to the actual laser output requirements, combining phase modulation and diffraction effects, and reconstructing the light field distribution by using the interference and diffraction principles to achieve light intensity conversion or light spot conversion, and realize the regulation of light intensity distribution and / or light spot shape to adapt to the requirements of different application scenarios. The integrated structure of laser transmission and modulation of optical fiber 10 avoids the influence of traditional external optical component installation deviation on beam quality. The output light field is more stable due to the influence of the amount of light, and is suitable for high-precision fields such as industrial processing and medical surgery. Therefore, the laser shaping device based on the output end face of the microstructured optical fiber provided by the present invention realizes the lightweight and high-efficiency of the beam shaping technology, and solves the core technical defects of the existing technology such as complex system and large loss. For example, the phase compensation of the Gaussian beam edge of the laser unit is used to achieve energy uniformity, and all the microstructure units 20 cooperate to adjust the light intensity Gaussian distribution to a flat-top distribution. For example, the spatial filtering or diffraction superposition of all the microstructure units 20 changes the shape of the output light spot, thereby As for outputting a light spot of a specific shape, for example, by setting the cross-sectional shape of the microstructure unit 20 to be linear, circular, square or elliptical, a linear, circular, square or elliptical light spot can be output accordingly, that is: by setting the cross-sectional shape of the microstructure unit 20 to be linear, a linear light spot can be output accordingly; by setting the cross-sectional shape of the microstructure unit 20 to be circular, a circular light spot can be output accordingly; by setting the cross-sectional shape of the microstructure unit 20 to be square, a square light spot can be output accordingly; by setting the cross-sectional shape of the microstructure unit 20 to be elliptical, an elliptical light spot can be output accordingly.

[0039] As a more preferred implementation of this embodiment, all microstructure units 20 are arranged side by side on the output end face 103, one end of the microstructure unit 20 is a wide end, and the other end of the microstructure unit 20 is a narrow end. The wide end is placed between the transmission section 102 and the narrow end. The microstructure unit 20 gradually narrows from the wide end to the narrow end along the two oblique side surfaces 201 on the microstructure unit 20. The angle between the two oblique side surfaces 201 on the microstructure unit 20 is 5° to 160°. The microstructure unit 20 changes the propagation direction of the laser beam by refraction and total reflection. The maximum width of the wide end is 1 μm to 1300 μm, and the distance between the narrow end and the wide end is 0.1 μm. m~650μm; the distance between any two adjacent microstructure units 20 is 1μm~650μm; the angle between the center line of the microstructure unit 20 and the center line of the transmission segment 102 is 0°~45°, the laser beam is controlled to be superimposed in a specific direction, and the laser output spot is adjusted to a linear spot. By adjusting the arrangement parameters of the microstructure unit 20, the line width and uniformity of the output laser can be optimized; in this embodiment, the number of microstructure units 20 arranged side by side at intervals on the output end face 103 is 1 or more, and the number of microstructure units 20 arranged on the output end face 103 can be determined in combination with actual usage requirements.

[0040] As a more preferred implementation of this embodiment, all microstructure units 20 are evenly distributed on the output end surface 103. The microstructure units 20 are two-dimensional structures, and the surface height of the microstructure units 20 is:

[0041]

[0042] Among them, z(x) is the surface height, c=1 / R is the curvature, R is the base circle radius, k is the cone constant, a4, a6... are high-order coefficients, which are used to correct high-order aberrations and optimize the uniformity of light intensity. Phase modulation and diffraction effects are introduced by changing the surface height of the microstructure unit 20. These effects are used to adjust the emission and interference of light, thereby modulating the light uniformity and changing the light field distribution.

[0043] As a preferred implementation of this embodiment, all microstructure units 20 are evenly distributed on the output end surface 103. The microstructure units 20 are three-dimensional structures, and the surface height of the microstructure units 20 is:

[0044]

[0045] Among them, z(x, y) is the surface height, c=1 / R is the curvature, R is the base circle radius, k is the cone constant, a4, a6... are high-order coefficients, which are used to correct high-order aberrations and optimize the uniformity of light intensity. Phase modulation and diffraction effects are introduced by changing the surface height of the microstructure unit 20 to change the light field distribution.

[0046] As a more preferred implementation of this embodiment, a nanograting is fixedly provided on the surface of the microstructure unit 20, and the period of the nanograting is less than 1 / 2 of the wavelength of the incident light; the groove depth of the nanograting is 200nm to 500nm and the groove width is 100nm to 300nm, forming a plasmon-enhanced grating, which suppresses Rayleigh scattering and Fresnel reflection, enhances transmission through the surface plasmon effect, and can effectively reduce scattering loss.

[0047] As a more preferred implementation of this embodiment, a first anti-reflection coating is fixedly provided on the outer surface of the microstructure unit 20, and the refractive index of the first anti-reflection coating gradually changes from 1.8 to 1.2 from the outer surface of the microstructure unit 20 to the outside; a second anti-reflection coating is fixedly provided on the inner surface of the microstructure unit 20, and the refractive index of the first anti-reflection coating gradually decreases from 1.5 to 1.1 from the inner surface of the microstructure unit 20 to the inside, thereby reducing Fresnel reflection, increasing the transmittance to more than 99%, and significantly improving energy utilization.

[0048] As a more preferred implementation of this embodiment, the surfaces of any two adjacent microstructure units 20 are transitionally connected by a wedge-shaped transition structure 202 to enhance the coupling efficiency; the width of the wedge-shaped transition structure 202 is 2μm-20μm, and the inclination angle is 5°~30°. The inclined surface transition of the wedge-shaped transition structure 202 can reduce mode field mismatch and enhance mode field coupling efficiency, thereby increasing the coupling efficiency by 10%~20%.

[0049] As a more preferred implementation of this embodiment, the microstructure unit 20 is square, circular, hemispherical, spherical, pyramidal, multi-step or parabolic, and can be flexibly selected based on actual shaping requirements.

[0050] As a more preferred implementation of this embodiment, the optical fiber 10 has a graded refractive index fiber segment 104, which is placed between the transmission segment 102 and the output end face 103. The graded refractive index fiber segment 104 can convert the laser beam transmitted by the transmission segment 102 into a collimated laser beam, and transmit the collimated laser beam to the output end face 103. The output end face 103 is located in the collimated position, and the laser beam forms parallel light and falls on the output end face 103, which can effectively improve the spot control accuracy of the microstructure unit 20 and reduce energy loss; the graded refractive index fiber is also called self-focusing fiber. The refractive index of the fiber is highest at the center and decreases radially. The light beam propagates in the optical fiber and can be automatically focused without dispersion.

[0051] As a more preferred implementation of this embodiment, the microstructure unit 20 is made by picosecond or femtosecond laser engraving with a pulse energy of 0.1μJ~1mJ and a repetition frequency of 10KHz~200MHz, which can achieve cold processing, reduce the heat-affected zone, and ensure accuracy.

[0052] As a more preferred implementation scheme of this embodiment, the microstructure unit 20 is made by dual laser beam writing. The dual laser beams used include a main ultrafast laser beam with a wavelength of 343nm~1030nm and a pulse energy of 100μJ~2mJ and a continuous laser-assisted controlled laser beam with a wavelength of 515nm or 532nm and a power of 50mW~3W. The dual laser beams used are coaxially focused on a preset path to engrave the microstructure unit 20. The picosecond laser processing accuracy reaches the sub-micron level. The use of dual laser beam writing can effectively reduce the edge cracks of the microstructure unit 20, improve the surface quality of the microstructure unit 20, and ensure efficient transmission of the laser beam.

[0053] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A laser shaping device based on a microstructured optical fiber output end face, characterized by: The optical fiber comprises an input end face, a transmission section, and an output end face in sequence. The input end face is used to be fixedly connected to a laser generator and receive a laser beam emitted by the laser generator. The transmission section can transmit the laser beam on the input end face to the output end face. The output end face has a plurality of microstructure units, and all of the microstructure units can collaboratively regulate the light intensity distribution and / or spot shape of the laser beam.

2. The laser shaping device based on the microstructured optical fiber output end face according to claim 1, characterized in that: All the microstructure units are arranged side by side at intervals on the output end face, one end of the microstructure unit is a wide end, and the other end of the microstructure unit is a narrow end, the wide end is placed between the transmission section and the narrow end, and the microstructure unit gradually narrows from the wide end to the narrow end along the two oblique side surfaces on the microstructure unit, the angle between the two oblique side surfaces on the microstructure unit is 5° to 160°, the maximum width of the wide end is 1μm to 1300μm, and the distance between the narrow end and the wide end is 0.1μm to 650μm; the distance between any two adjacent microstructure units is 1μm to 650μm; the angle between the center line of the microstructure unit and the center line of the transmission section is 0° to 45°.

3. The laser shaping device based on the microstructured optical fiber output end face according to claim 1, characterized in that: All the microstructure units are evenly distributed on the output end surface. The microstructure units are two-dimensional structures. The surface height of the microstructure units is: Wherein, z(x) is the surface height, c=1 / R is the curvature, R is the base circle radius, k is the cone constant, and a4, a6, ... are higher-order coefficients used to correct higher-order aberrations and optimize light intensity uniformity.

4. The laser shaping device based on the microstructured optical fiber output end face according to claim 1, characterized in that: All the microstructure units are evenly distributed on the output end surface. The microstructure units are three-dimensional structures. The surface height of the microstructure units is: Wherein, z(x, y) is the surface height, c=1 / R is the curvature, R is the base circle radius, k is the cone constant, and a4, a6, ... are higher-order coefficients used to correct higher-order aberrations and optimize light intensity uniformity.

5. The laser shaping device based on the microstructured optical fiber output end face according to claim 1, characterized in that: A nano grating is fixedly provided on the surface of the microstructure unit, wherein the period of the nano grating is less than 1 / 2 of the wavelength of the incident light; the groove depth of the nano grating is 200nm to 500nm, and the groove width is 100nm to 300nm.

6. The laser shaping device based on the microstructured optical fiber output end face according to claim 1, characterized in that: A first anti-reflection coating is fixedly provided on the outer surface of the microstructure unit, and the refractive index of the first anti-reflection coating gradually changes from 1.8 to 1.2 from the outer surface of the microstructure unit to the outside; a second anti-reflection coating is fixedly provided on the inner surface of the microstructure unit, and the refractive index of the first anti-reflection coating gradually decreases from 1.5 to 1.1 from the inner surface of the microstructure unit to the inside.

7. The laser shaping device based on the microstructured optical fiber output end face according to claim 1, characterized in that: The surfaces of any two adjacent microstructure units are transitionally connected via a wedge-shaped transition structure; the width of the wedge-shaped transition structure is 2 μm-20 μm, and the inclination angle is 5° to 30°.

8. The laser shaping device based on the microstructured optical fiber output end face according to claim 1, characterized in that: The microstructure unit is in the shape of a square, a circle, a hemisphere, a sphere, a pyramid, a multi-step or a parabola.

9. The laser shaping device based on the microstructured optical fiber output end face according to claim 1, characterized in that: The optical fiber has a graded refractive index optical fiber segment, which is placed between the transmission segment and the output end face. The graded refractive index optical fiber segment can convert the laser beam transmitted by the transmission segment into a collimated laser beam and transmit the collimated laser beam to the output end face.

10. The laser shaping device based on the microstructured optical fiber output end face according to claim 1, characterized in that: The microstructure unit is made by engraving with a picosecond or femtosecond laser having a pulse energy of 0.1 μJ to 1 mJ and a repetition frequency of 10 KHz to 200 MHz.

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