Inner cavity frequency doubling blue light fiber laser welding device based on fiber bragg grating

Abstract

The utility model discloses an inner cavity frequency doubling blue light fiber laser welding device based on a fiber bragg grating, and relates to the technical field of fiber lasers. The semiconductor pump light source is connected to the input end of the optical fiber wavelength division multiplexer, the output end of the optical fiber wavelength division multiplexer is sequentially connected with the ytterbium-doped optical fiber, the frequency doubling crystal and the end face reflector, and the optical fiber bragg grating is obtained by adopting a purple light mask method in an inscribing mode, connected to the other input end of the wavelength division multiplexer and then sequentially connected with the dichroscope, the collimator and the welding head. Under excitation of pump light, ions in the ytterbium-doped optical fiber generate stimulated radiation, laser oscillates in a resonant cavity formed by the fiber Bragg grating and the end face reflector, 490 nm blue light is generated through the frequency doubling crystal, the blue light is transmitted through the two-phase color mirror, 980 nm light is reflected through the two-phase color mirror, and finally the laser is output through the welding head. The fiber bragg grating is high in inscribing resolution, high in stability, high in production efficiency, high in inner cavity frequency doubling electro-optical conversion efficiency, high in quality of output blue light beams, compact in structure and suitable for welding of high-reflectivity materials.

Description

Technical Field

[0001] This utility model relates to the field of fiber laser technology, and more specifically to a cavity frequency doubling blue fiber laser welding device based on a fiber grating. Background Technology

[0002] In the welding field, kilowatt-level infrared fiber lasers have been widely used and are highly favored for their high efficiency and high power. However, infrared lasers do not perform ideally with highly reflective metals such as Al, Cu, and Au. Highly reflective metals have a low absorption rate of infrared lasers, around 5%, resulting in low energy conversion efficiency and making them prone to defects such as porosity, cracks, and incomplete fusion during processing. In contrast, blue lasers with wavelengths in the 450-500nm range have an absorption rate more than 10 times higher. Therefore, blue lasers have enormous potential in the welding of highly reflective non-ferrous metals.

[0003] Despite the immense application potential of blue lasers, several bottlenecks remain in their technological development. Current technologies for obtaining blue light from solid-state lasers typically involve directly fabricating semiconductor laser diodes in the blue light band using semiconductor materials. This method requires expensive equipment and substrate materials, and the output beam quality is relatively poor, significantly limiting its application in welding. While frequency doubling of blue laser light from fiber lasers is primarily achieved through external cavity frequency doubling in a spatial structure, the laser beam passes through the frequency doubling crystal only once, resulting in a significant reduction in intensity and lower frequency conversion efficiency. Furthermore, achieving substantial frequency doubling output typically requires higher pump power, leading to increased system energy consumption and cost.

[0004] Therefore, how to propose an intracavity frequency-doubled blue fiber laser welding device based on fiber Bragg grating to achieve high-power, high-beam-quality blue light output while reducing system energy consumption and complexity is a problem that urgently needs to be solved by those skilled in the art. Utility Model Content

[0005] In view of this, the present invention provides a cavity-doubled blue fiber laser welding device based on a fiber grating. The fiber grating is fabricated using a violet photomask method, which provides high resolution, high stability, and high production efficiency, making it suitable for harsh industrial environments. Simultaneously, the cavity frequency doubling method results in high electro-optical conversion efficiency, leading to higher beam quality in the obtained blue laser output, making it suitable for welding highly reflective materials.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An intracavity frequency-doubled blue fiber laser welding device based on fiber Bragg grating, comprising a fiber wavelength division multiplexer;

[0008] The input end of the fiber wavelength division multiplexer is connected to one end of the fiber Bragg grating, and a dichroic mirror, a collimator, and a welding head are sequentially connected to the other end of the fiber Bragg grating.

[0009] The output of the fiber wavelength division multiplexer is subsequently connected to a ytterbium-doped fiber, a frequency-doubling crystal, and an end-face mirror in sequence.

[0010] The input of the fiber wavelength division multiplexer is also connected to a semiconductor pump source.

[0011] Preferably, the fiber Bragg grating and the end face reflector are used as the front cavity mirror and the rear cavity mirror, respectively, to form a resonant cavity.

[0012] Preferably, the semiconductor pump source is a 915nm semiconductor pump source.

[0013] Preferably, the fiber wavelength division multiplexer is a 915 / 978nm fiber wavelength division multiplexer.

[0014] Preferably, the fiber Bragg grating is a fiber grating with a center wavelength of 980 nm obtained by using a violet photomask writing method.

[0015] Preferably, the dichroic mirror has a transmittance of more than 90% for 490nm blue light and a reflectance of more than 90% for 980nm wavelength light.

[0016] As can be seen from the above technical solution, compared with the prior art, this utility model discloses an intracavity frequency-doubling blue fiber laser welding device based on a fiber grating. A high-reflectivity fiber grating is written using a violet photomask method, and the written fiber grating with a center wavelength of 980nm in the reflection spectrum serves as the frequency selection device for the fiber optic system. A 915nm semiconductor pump is connected to a 915 / 978nm fiber wavelength division multiplexer. Another input port of the 915 / 978nm fiber wavelength division multiplexer is connected to a high-reflectivity Bragg fiber grating, and the output port of the 915 / 978nm fiber wavelength division multiplexer is connected to a ytterbium-doped fiber. The ytterbium-doped fiber is subsequently connected to a frequency-doubling crystal and an end-face mirror. The laser oscillates in the resonant cavity formed by the fiber Bragg grating and the end-face mirror, simultaneously performing intracavity frequency doubling. The fiber Bragg grating is subsequently connected to a dichroic mirror and a collimator, and the collimator is connected to the welding head for blue light output. This invention features a compact structure, high output power, and higher frequency doubling efficiency compared to fiber lasers, enabling the production of high-power, high-beam-quality blue light output for welding highly reflective materials. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0018] Figure 1 This is a structural schematic diagram of the present invention.

[0019] In the figure, 101-semiconductor pump source; 102-fiber wavelength division multiplexer; 103-ytterbium-doped fiber; 104-frequency doubling crystal; 105-end face mirror; 106-fiber Bragg grating; 107-dichroic mirror; 108-collimator; 109-welding head. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0021] like Figure 1 As shown, this embodiment of the invention proposes an intracavity frequency doubling blue fiber laser welding device based on a fiber grating, including a fiber wavelength division multiplexer 102.

[0022] The input end of the fiber wavelength division multiplexer 102 is connected to one end of the fiber Bragg grating 106, and the other end of the fiber Bragg grating 106 is subsequently connected to a dichroic mirror 107, a collimator 108, and a welding head 109.

[0023] The output of the fiber wavelength division multiplexer 102 is subsequently connected to a ytterbium-doped fiber 103, a frequency doubling crystal 104, and an end-face mirror 105 in sequence.

[0024] The input of the fiber wavelength division multiplexer 102 is also connected to the semiconductor pump source 101.

[0025] A resonant cavity is formed by using a fiber Bragg grating 106 and an end-face mirror 105 as the front and rear cavity mirrors, respectively.

[0026] Semiconductor pump source 101 is a 915nm semiconductor pump source.

[0027] The fiber wavelength division multiplexer 102 is a 915 / 978nm fiber wavelength division multiplexer.

[0028] The fiber Bragg grating 106 is a fiber grating with a reflection spectrum center wavelength of 980 nm, obtained by using a violet photomask writing method.

[0029] The fabrication steps of an intracavity frequency-doubled blue fiber laser welding device based on a fiber Bragg grating are as follows:

[0030] Step a: Laser writing is performed on the fiber Bragg grating 106, and a fiber grating with a center wavelength of 980nm in the reflection spectrum is obtained by using the ultraviolet photomask writing method.

[0031] Step b: Connect the 915nm semiconductor pump light source 101 to the input of the 915 / 978nm fiber wavelength division multiplexer 102;

[0032] Step c: Connect ytterbium-doped fiber 103, frequency doubling crystal 104, and end face mirror 105 sequentially to the output end of the 915 / 978nm fiber wavelength division multiplexer 102.

[0033] Step d: Connect the inscribed fiber Bragg grating 106 to the other input of the 915 / 978nm fiber wavelength division multiplexer 102;

[0034] Step e: After the fiber Bragg grating 106, a dichroic mirror 107, a collimator 108, and a welding head 109 are connected in sequence for blue light output to achieve welding of highly reflective materials.

[0035] The writing of fiber Bragg grating 106 includes the following steps:

[0036] Step a1: Apply photoresist to the optical fiber using a spin coater to form a uniform photoresist film;

[0037] Step a2: Using an ultraviolet lithography machine, the designed grating structure pattern is transferred onto the photoresist through optical projection of the mask;

[0038] Step a3: Develop the exposed photoresist and remove the photoresist from the unexposed or exposed areas according to the exposure conditions.

[0039] Step a4: Using a wet etching process, the developed photoresist pattern is transferred to the surface of the optical fiber to form a grating structure;

[0040] Step a4: Connect the two ends of the fiber Bragg grating to the spectrometer and the light source respectively, observe the parameters, and ensure that the manufacturing quality meets the requirements.

[0041] In the specific implementation process, the pump light is incident on the optical fiber system. The fiber Bragg grating 106, ytterbium-doped fiber 103, frequency doubling crystal 104, and end-face mirror 105 ensure the formation of the fundamental frequency oscillation. The fiber Bragg grating 106 and end-face mirror 105 act as front and rear cavity mirrors. Under the continuous excitation of the semiconductor pump source 101, the ytterbium-doped luminescent ions in the fiber core undergo population inversion, generating stimulated emission. The laser oscillates in the resonant cavity formed by the fiber Bragg grating 106 and end-face mirror 105, and simultaneously generates 490nm blue light after passing through the frequency doubling crystal 104.

[0042] The dichroic mirror 107 has a transmittance of more than 90% for the 490nm blue light generated by the frequency doubling crystal 104 and a reflectance of more than 90% for the 980nm wavelength light. The dichroic mirror 107 selects to transmit the frequency-doubled light generated by the frequency doubling crystal 104 to the collimator, and the collimator 108 is connected to the welding head 109 to output blue light.

[0043] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0044] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A cavity frequency-doubled blue fiber laser welding device based on a fiber Bragg grating, characterized in that, Includes fiber wavelength division multiplexer (102); The input end of the fiber wavelength division multiplexer (102) is connected to one end of the fiber Bragg grating (106), and the other end of the fiber Bragg grating (106) is subsequently connected to a dichroic mirror (107), a collimator (108), and a welding head (109). The output of the fiber wavelength division multiplexer (102) is subsequently connected to a ytterbium-doped fiber (103), a frequency doubling crystal (104), and an end-face mirror (105) in sequence. The input of the fiber wavelength division multiplexer (102) is also connected to a semiconductor pump source (101).

2. The cavity frequency-doubled blue fiber laser welding device based on a fiber Bragg grating according to claim 1, characterized in that, The fiber Bragg grating (106) and the end face mirror (105) are used as the front cavity mirror and the rear cavity mirror, respectively, to form a resonant cavity.

3. The cavity frequency-doubled blue fiber laser welding device based on a fiber Bragg grating according to claim 1, characterized in that, The semiconductor pump source (101) is a 915nm semiconductor pump source.

4. The cavity frequency-doubled blue fiber laser welding device based on a fiber Bragg grating according to claim 1, characterized in that, The fiber wavelength division multiplexer (102) is a 915 / 978nm fiber wavelength division multiplexer.

5. The cavity frequency-doubled blue fiber laser welding device based on a fiber Bragg grating according to claim 1, characterized in that, The fiber Bragg grating (106) is a fiber grating with a reflection spectrum center wavelength of 980 nm obtained by using a violet photomask writing method.

6. The cavity frequency-doubled blue fiber laser welding device based on a fiber Bragg grating according to claim 1, characterized in that, The dichroic mirror (107) has a transmittance of more than 90% for 490nm blue light and a reflectance of more than 90% for 980nm wavelength light.

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