A laser shaping device based on the output end face of a microstructured fiber

Abstract

The application discloses a laser shaping device based on a microstructure optical fiber output end face, relates to the technical field of laser shaping, and discloses the laser shaping device based on the microstructure optical fiber output end face, which comprises an optical fiber, the optical fiber has an input end face, a transmission section and an output end face in sequence, the input end face is used for being fixedly connected with a laser generator and receiving 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 is provided with a plurality of microstructure units, and all the microstructure units can cooperatively control the light intensity distribution and / or the spot shape of the laser beam; the laser shaping device based on the microstructure optical fiber output end face disclosed by the application has the advantages of simple structure, high integration degree and high efficiency and low loss.

Description

Technical Field

[0001] This invention relates to the field of laser shaping technology, and in particular to a laser shaping device based on the output end face of a microstructured optical fiber. Background Technology

[0002] In laser industrial manufacturing, Gaussian-like laser beams are typically converted into flat-top beams. Flat-top beams are characterized by uniform energy at the top and very sharp boundaries, meaning a short "transition zone" and a steep energy curve (90% to 10%) that clearly distinguishes the processed and unprocessed areas. Therefore, flat-top beams are well-suited for various laser processing applications, achieving both high efficiency and high precision.

[0003] In traditional laser reshaping techniques, external optical components such as spatial light modulators (SLMs), diffractive optical elements (DOEs), lens groups, or mirrors are typically used to control the laser beam, achieving uniform intensity distribution (e.g., converting a Gaussian beam into a flat-top beam) or changing the beam shape (e.g., converting a circular beam into a square or linear beam). However, the following limitations exist:

[0004] 1. Complex system: It requires the introduction of multiple sets of optical components, resulting in a large optical path structure, high adjustment difficulty, and strict requirements on the assembly and adjustment accuracy of optical devices;

[0005] 2. High energy loss: When the light beam passes through multiple optical interfaces, it is prone to 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 simple and highly efficient integrated laser shaping device to overcome the shortcomings of existing technologies. Summary of the Invention

[0008] The purpose of this invention is to provide a laser shaping device based on the output end face of a microstructured optical fiber, so as to solve the problems existing in the prior art. It has a simple structure, high integration, high efficiency and low loss.

[0009] To achieve the above objectives, the present invention provides the following solution:

[0010] This invention provides a laser shaping device based on a microstructured optical fiber output end face, comprising an optical fiber having an input end face, a transmission section, and an output end face sequentially thereon. The input end face is used to be fixedly connected to a laser generator and to 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 control the 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 each microstructure unit is a wide end, and the other end is a narrow end. The wide end is positioned between the transmission segment and the narrow end. The microstructure unit gradually narrows from the wide end to the narrow end along two inclined surfaces. The included angle between the two inclined surfaces of the microstructure unit is 5° to 160°. The maximum width of the wide end is 1μm to 1300μm. 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 centerline of the microstructure unit and the centerline of the transmission segment is 0° to 45°.

[0012] Preferably, all the microstructure units are uniformly distributed on the output end face, and the microstructure unit is a two-dimensional structure with a surface height of:

[0013]

[0014] Where z(x) is the surface height, c = 1 / R is the curvature, R is the radius of the base circle, k is the conic 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 uniformly distributed on the output end face, and the microstructure unit has a three-dimensional structure with a surface height of:

[0016]

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

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

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

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

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

[0022] Preferably, the optical fiber has a graded refractive index fiber segment, which is placed between the transmission segment and the output end face. The graded refractive index 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 fabricated using a picosecond or femtosecond laser with a pulse energy of 0.1 μJ to 1 mJ and a repetition frequency of 10 kHz to 200 MHz.

[0024] The present invention achieves the following technical effects compared to the prior art:

[0025] The laser shaping device based on the output end face of a microstructured optical fiber provided by this invention has several microstructure units arranged on the output end face. The intensity distribution and / or spot shape of the laser beam are controlled collaboratively by all microstructure units. The output spot characteristics are directly controlled by all microstructure units, eliminating the need for additional spatial optical path modulators, diffractive optical elements, or complex lens groups. This significantly reduces the number of optical components, making the system structure more compact and easy to integrate into miniaturized and portable devices. The structure is simple and highly integrated. After the laser propagates inside the optical fiber, it is directly modulated and output by all microstructure units, avoiding energy losses such as reflection and scattering caused by traditional optical interfaces, improving light energy utilization, and achieving high efficiency and low loss. All microstructure units... The structural units can be designed with specific periodic or non-periodic arrangements to meet actual laser output requirements. By combining phase modulation and diffraction effects, the light field distribution can be reconstructed using interference and diffraction principles to achieve light intensity conversion or spot conversion, thereby controlling the light intensity distribution and / or spot shape to adapt to different application scenarios. The integrated structure of laser transmission and modulation in optical fiber avoids the influence of beam quality on the assembly and adjustment deviations of traditional external optical components, resulting in higher stability of the output light field. It is suitable for high-precision fields such as industrial processing and medical surgery. Thus, the laser shaping device based on the output end face of microstructured optical fiber provided by this invention achieves lightweight and efficient beam shaping technology, solving the core technical defects of existing technologies such as system complexity and high loss. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

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

[0028] Figure 2 for Figure 1 A schematic diagram of a microstructure unit placed on the output end face of the device;

[0029] Figure 3 for Figure 2 Cross-sectional view of the structure;

[0030] Figure 4 for Figure 1 A schematic diagram of multiple microstructure units arranged side by side on the output end face of the device;

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

[0032] Figure 6 for Figure 4 Cross-sectional view of the structure;

[0033] In the figure: 10-fiber, 101-input end face, 102-transmission section, 103-output end face, 104-gradient refractive index fiber section, 20-microstructure unit, 201-oblique side surface, 202-wedge transition structure. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] The purpose of this invention is to provide a laser shaping device based on the output end face of a microstructured optical fiber, so as to solve the problems existing in the prior art. It has a simple structure, high integration, high efficiency and low loss.

[0036] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be 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 the output end face of a microstructured optical fiber, including an optical fiber 10. The optical fiber 10 has an input end face 101, a transmission section 102, and an output end face 103 in sequence. The input end face 101 is used to be fixedly connected to a laser generator and to receive the laser beam emitted by the laser generator. The transmission section 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. All microstructure units 20 can coordinately control the 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 this invention has a plurality of microstructure units 20 arranged on the output end face 103. The intensity distribution and / or spot shape of the laser beam are controlled collaboratively by all microstructure units 20, and the output spot characteristics are directly controlled by all microstructure units 20. This eliminates the need for additional spatial optical path modulators, diffractive optical elements, or complex lens groups, significantly reducing the number of optical components and making the system structure more compact. It is easy to integrate into miniaturized and portable devices, exhibiting a simple structure and high integration. The laser beam is directly shaped after transmission within the optical fiber 10. With microstructure unit 20 for modulation output, energy loss due to reflection and scattering caused by traditional optical interfaces is avoided, improving light energy utilization and achieving high efficiency and low loss. All microstructure units 20 can be arranged in specific periodic or non-periodic patterns according to actual laser output requirements. Combining phase modulation and diffraction effects, the light field distribution is reconstructed using interference and diffraction principles to achieve light intensity conversion or spot conversion, realizing the control of light intensity distribution and / or spot shape, adapting to different application scenarios. The integrated laser transmission and modulation structure of fiber 10 avoids the impact of beam quality on traditional external optical element assembly and adjustment deviations. Due to the influence of quantity, the output light field stability is higher, making it suitable for high-precision fields such as industrial processing and medical surgery. Therefore, the laser shaping device based on the output end face of a microstructured optical fiber provided by this invention achieves lightweight and efficient beam shaping technology, solving the core technical defects of existing technologies such as system complexity and high loss. For example, phase compensation at the edge of the Gaussian beam of the laser unit achieves energy homogenization, and all microstructure units 20 collaboratively regulate the Gaussian distribution of light intensity to a flat-top distribution. For example, spatial filtering or diffraction superposition of all microstructure units 20 changes the shape of the output light spot, from... The output can be 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. That is: by setting the cross-sectional shape of the microstructure unit 20 to be linear, a linear light spot can be output; by setting the cross-sectional shape of the microstructure unit 20 to be circular, a circular light spot can be output; by setting the cross-sectional shape of the microstructure unit 20 to be square, a square light spot can be output; and by setting the cross-sectional shape of the microstructure unit 20 to be elliptical, an elliptical light spot can be output.

[0039] In a preferred embodiment of this invention, all microstructure units 20 are arranged side-by-side at intervals on the output end face 103. One end of each microstructure unit 20 is a wide end, and the other end is a narrow end. The wide end is positioned between the transmission section 102 and the narrow end. The microstructure unit 20 gradually narrows from the wide end to the narrow end along two inclined surfaces 201. The included angle between the two inclined surfaces 201 of the microstructure unit 20 is 5° to 160°. The microstructure unit 20 changes the propagation direction of the laser beam through refraction and total internal 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. The distance between any two adjacent microstructure units 20 is 1 μm to 650 μm; the angle between the center line of the microstructure unit 20 and the center line of the transmission section 102 is 0° to 45°. The laser beam is controlled to be superimposed in a specific direction, and the laser output spot is adjusted into a linear spot. By adjusting the arrangement parameters of the microstructure unit 20, the linewidth 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 one or more, and the number of microstructure units 20 arranged on the output end face 103 can be determined according to the actual usage requirements.

[0040] In a preferred embodiment of this invention, all microstructure units 20 are uniformly distributed on the output end face 103. Each microstructure unit 20 is a two-dimensional structure, and the surface height of each microstructure unit 20 is:

[0041]

[0042] Where z(x) is the surface height, c = 1 / R is the curvature, R is the radius of the base circle, k is the conic constant, and a4, a6... are higher-order coefficients used to correct higher-order aberrations and optimize light intensity uniformity. The change in surface height of the microstructure unit 20 introduces phase modulation and diffraction effects, which adjust the emission and interference of light, thereby modulating the light uniformity and changing the light field distribution.

[0043] In a preferred embodiment of this invention, all microstructure units 20 are uniformly distributed on the output end face 103. Each microstructure unit 20 has a three-dimensional structure, and the surface height of each microstructure unit 20 is:

[0044]

[0045] Where z(x, y) is the surface height, c = 1 / R is the curvature, R is the radius of the base circle, k is the conic constant, and a4, a6... are higher-order coefficients used to correct higher-order aberrations and optimize light intensity uniformity. The change in surface height of the microstructure unit 20 introduces phase modulation and diffraction effects, thereby changing the light field distribution.

[0046] As a preferred embodiment of this invention, a nanograting is fixed on the surface of the microstructure unit 20. The period of the nanograting is less than 1 / 2 of the incident light wavelength. The groove depth of the nanograting is 200nm to 500nm and the groove width is 100nm to 300nm, forming a plasmonic enhancement grating. This suppresses Rayleigh scattering and Fresnel reflection, and enhances transmission through the surface plasmon effect, effectively reducing scattering loss.

[0047] In a preferred embodiment of this invention, a first anti-reflective coating is fixedly provided on the outer surface of the microstructure unit 20. From the outer surface of the microstructure unit 20 outwards, the refractive index of the first anti-reflective coating gradually changes from 1.8 to 1.2. A second anti-reflective coating is fixedly provided on the inner surface of the microstructure unit 20. From the inner surface of the microstructure unit 20 inwards, the refractive index of the first anti-reflective coating gradually decreases from 1.5 to 1.1, thereby reducing Fresnel reflection, increasing transmittance to over 99%, and significantly improving energy utilization.

[0048] In a preferred embodiment of this invention, the surfaces of any two adjacent microstructure units 20 are connected by a wedge-shaped transition structure 202 to enhance coupling efficiency. The width of the wedge-shaped transition structure 202 is 2μm-20μm and the tilt angle is 5°-30°. The inclined transition of the wedge-shaped transition structure 202 can reduce mode field mismatch and enhance mode field coupling efficiency, thereby improving the coupling efficiency by 10%-20%.

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

[0050] In a preferred embodiment of this invention, the optical fiber 10 has a graded refractive index fiber segment 104, which is positioned 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 in a collimated position, and the laser beam forms parallel light that 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 known as a self-focusing fiber. The refractive index of the fiber is highest at the center and decreases radially. The beam can automatically focus without dispersion when propagating in the fiber.

[0051] As a preferred embodiment of this invention, the microstructure unit 20 is fabricated using a picosecond or femtosecond laser with a pulse energy of 0.1 μJ to 1 mJ and a repetition frequency of 10 kHz to 200 MHz, which enables cold processing, reduces the heat-affected zone, and ensures accuracy.

[0052] As a preferred embodiment of this invention, the microstructure unit 20 is fabricated using dual laser beams. The dual laser beams include a main ultrafast laser beam with a wavelength of 343nm to 1030nm and a pulse energy of 100μJ to 2mJ, and a continuous laser-assisted control laser beam with a wavelength of 515nm or 532nm and a power of 50mW to 3W. The dual laser beams are coaxially focused on a preset path to fabricate the microstructure unit 20. The picosecond laser processing accuracy reaches the submicron level. Using dual laser beams for fabrication can effectively reduce edge cracks in the microstructure unit 20, improve the surface quality of the microstructure unit 20, and ensure efficient transmission of the laser beam.

[0053] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A laser shaping device based on the output end face of a microstructured optical fiber, characterized in that: The optical fiber includes 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 to receive the 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 number of microstructure units, and all the microstructure units can coordinate to control the intensity distribution and / or spot shape of the laser beam. A nanograting is fixed on the surface of the microstructure unit. The nanograting forms a plasmon-enhanced grating, which suppresses Rayleigh scattering and Fresnel reflection and enhances transmission through the surface plasmon effect. The optical fiber has a graded refractive index fiber segment, which is placed between the transmission segment and the output end face. The graded refractive index 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.

2. The laser shaping device based on the microstructure 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 each microstructure unit is a wide end, and the other end is a narrow end. The wide end is positioned between the transmission segment and the narrow end. The microstructure unit gradually narrows from the wide end to the narrow end along two inclined surfaces. The angle between the two inclined surfaces of the microstructure unit is 5° to 160°. The maximum width of the wide end is 1μm to 1300μm. 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 centerline of the microstructure unit and the centerline of the transmission segment is 0° to 45°.

3. The laser shaping device based on the microstructure fiber output end face according to claim 1, characterized in that: All the aforementioned microstructure units are uniformly distributed on the output end face. Each microstructure unit has a two-dimensional structure, and the surface height of the microstructure unit is: ， Where z(x) is the surface height, c=1 / R is the curvature, R is the radius of the base circle, k is the conic 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 microstructure fiber output end face according to claim 1, characterized in that: All the aforementioned microstructure units are uniformly distributed on the output end face. Each microstructure unit has a three-dimensional structure, and the surface height of the microstructure unit is: ， Where z(x, y) is the surface height, c=1 / R is the curvature, R is the radius of the base circle, k is the conic 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 output end face of a microstructured optical fiber according to claim 1, characterized in that: The period of the nanograting is less than 1 / 2 of the incident light wavelength; the groove depth of the nanograting is 200nm~500nm and the groove width is 100nm~300nm.

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

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

8. The laser shaping device based on the output end face of a microstructured optical fiber according to claim 1, characterized in that: The microstructure units are square, circular, hemispherical, spherical, pyramidal, multi-step, or parabolic.

9. The laser shaping device based on the microstructure fiber output end face according to claim 1, characterized in that: The microstructure units are fabricated using picosecond or femtosecond lasers with pulse energy of 0.1 μJ to 1 mJ and repetition frequency of 10 kHz to 200 MHz.

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