Fiber laser based on chirp tilted fiber grating
Through chirped tilt fiber grating filtering technology, the problems of 1030nm ASE and self-excitation oscillation in high-power ytterbium-doped fiber lasers are solved, and efficient spectral purification and high-brightness 1018nm laser output are achieved.
Patent Information
- Application Number
- CN202422073252.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-26
- Publication Date
- 2025-08-08
- Estimated Expiration
- 2034-08-26
AI Technical Summary
The prior art is difficult to effectively suppress 1030nm ASE and self-excitation oscillation in high-power ytterbium-doped fiber lasers, resulting in fiber fuse, lateral mode instability and reduced optical efficiency.
Chirped inclined fiber grating filtering technology is used, and the filtering effect of chirped inclined fiber grating is used to filter out ASE near 1030nm and reduce its gain, purify the spectral components, and obtain a pure 1018nm high-power fiber with pump laser.
Effective suppression of 1030nm ASE and self-excitation is achieved, the optical efficiency and safety of the fiber laser are improved, and the output of high-power, high-brightness 1018nm laser is output.
Smart Images
Figure CN223206620U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to an optical fiber laser based on a chirped tilted optical fiber grating. Background Art
[0002] With the rapid development of industrial laser technology, military and some industrial applications have continuously put forward higher requirements for the output power and brightness of lasers. In order to obtain high-power fiber lasers with higher brightness, it is currently generally achieved through the Mopa single-fiber amplification solution, rather than through low-power module beam combining. Ultra-high-power single-fiber Mopa amplification solutions often generate waste heat due to the problem of photon loss, which causes severe heating of the active fiber, and then causes transverse mode instability, and ultimately limits the upper limit of the single-fiber output power. To solve this problem, co-band pumping is often used. The co-band pumping technology in fiber laser technology can greatly reduce the risks of fiber melting, transverse mode instability, and other risks caused by fiber thermal problems by using a pump laser with low photon loss. The laser light source used in high-power ytterbium-doped fiber laser co-band pumping technology is generally obtained through two methods: ytterbium-doped gain fiber combined with resonant cavity or mopa amplification. Given the absorption spectrum of ytterbium-doped fiber, the laser wavelength of the co-band pump light source should be less than 1030nm. However, this wavelength band is also within the absorption spectrum of ytterbium-doped fiber, which means that the reabsorption effect is strong. For the 1030nm wavelength, which is the emission peak and has a low reabsorption effect, the laser oscillation threshold of lasers with a central wavelength less than 1030nm is higher, making it more difficult to form laser oscillation. Therefore, high-power ytterbium-doped fiber lasers with a central wavelength less than 1030nm are generally accompanied by ASE or self-excited output of the 1030nm wavelength laser. The 1018nm wavelength light source serves as the co-band pump laser for the typical ytterbium-doped 1080nm laser. Therefore, obtaining high-power and high-brightness 1018nm pump laser is particularly important for high-power and bright 1080nm ytterbium-doped fiber lasers. Among them, high-power, high-brightness 1018nm pump light sources are more conducive to improving the pump injection capability, reliability, and amplification capability of the amplification system. 1018nm high-power, high-brightness lasers are generally obtained by pumping high-absorption ytterbium-doped fibers at 915nm, 940nm, or 976nm. Because 1018nm is within the strong absorption wavelength range of ytterbium-doped active fibers, it is more difficult to obtain gain at a wavelength of 1030nm, which is located in the strong emission peak band of ytterbium-doped active fibers. As a result, ASE and self-oscillation are very likely to occur in 1018nm light source systems based on ytterbium-doped fibers, which will limit the acquisition of high-power, high-brightness 1018nm lasers and may also cause certain damage to the optical system.
[0003] Existing solutions often involve shortening the active fiber or increasing the reflectivity of the low-reflection grating. While shortening the active fiber suppresses ASE and self-oscillation, it also reduces pump laser absorption, ultimately reducing optical efficiency. Increasing the reflectivity of the low-reflection grating increases the laser energy density within the cavity, potentially heating the active fiber due to 1018nm reabsorption. Furthermore, it can cause nonlinear effects, potentially compromising the safety of the optical system. Utility Model Content
[0004] The purpose of this utility model is to provide a fiber laser based on a chirped tilted fiber Bragg grating. In order to obtain a 1018nm laser with a purer spectrum and effectively suppress 1030nm ASE or self-excitation, the filtering effect of the chirped tilted fiber Bragg grating is utilized to filter out ASE near 1030nm, increasing loss and reducing 1030nm gain, thereby purifying the spectral components and obtaining a high-power ytterbium-doped fiber in-band pump laser with a pure spectrum and a central wavelength less than 1030nm.
[0005] To solve the above problems, the utility model provides a fiber laser based on chirped tilted fiber Bragg grating, comprising a pump source, a first beam combiner, a second beam combiner, an active fiber, a high-reflection grating, a low-reflection grating, and a tilted fiber Bragg grating, characterized in that: the pump fiber of the first beam combiner is connected to the pump source, and the output fiber of the first beam combiner is connected to the first end of the high-reflection grating; the second end of the high-reflection grating is connected to the first end of the active fiber, the second end of the active fiber is connected to the first end of the tilted fiber Bragg grating, and the second end of the tilted fiber Bragg grating is connected to the first end of the low-reflection grating; the pump fiber of the second beam combiner is connected to the pump source, the first end of the central fiber of the second beam combiner is connected to the second end of the low-reflection grating, and the second end of the central fiber of the second beam combiner outputs the laser in the resonant cavity; the tilted fiber Bragg grating is a chirped tilted fiber Bragg grating, which is used for filtering, and the chirped tilted fiber Bragg grating is used for ASE of the laser and suppression of self-excitation.
[0006] Preferably, the central wavelength of the chirped tilted fiber grating is 1030 nm, and the bandwidth is greater than 15 nm.
[0007] Preferably, it further comprises a stripper and an output device, the second end of the central fiber of the second combiner is connected to the first side of the stripper, the second side of the stripper is connected to the first side of the output device, and the second side of the output device is used to output laser.
[0008] Preferably, the laser output by the resonant cavity is an ytterbium-doped fiber in-band pump laser with a central wavelength less than 1030 nm.
[0009] Preferably, the resonant cavity outputs a 1018 nm fiber laser output greater than 1500 W.
[0010] Preferably, the pump source uses multiple pump light sources, including a forward pump light source and a reverse pump light source; the pump source is composed of a laser diode semiconductor laser or a fiber laser pump light source with a pump light operating wavelength of 915, 940nm or 976nm, wherein the output power of a single pump light source is greater than 600W.
[0011] Preferably, the first beam combiner adopts a forward 3*1 pump beam combiner, and the second beam combiner adopts a reverse (2+1)*1 beam combiner.
[0012] Preferably, the chirped tilted fiber grating is obtained by mask plate combined with femtosecond laser fiber core etching, and the core etching obtains its characteristics of high transparency for core transmission at 1018nm, and the core laser at 1030nm position for core transmission is coupled into the cladding.
[0013] Preferably, the fiber parameters of the pump fibers of the first and second combiners are 135 / 155 / 0.22, the fiber parameters of the central signal fiber are 30 / 250 / 0.065, and the length of the active fiber is greater than 5 m.
[0014] Preferably, the central wavelength of the high-reflection grating is 1018nm, the reflection bandwidth is 3nm, and the reflectivity is ≥99.5%; the central wavelength of the low-reflection grating is 1018nm, the reflection bandwidth is 1nm, and the reflectivity is 15%-5%; the output fiber type is 30 / 250 / 0.065, and the internal stripper is used to strip the cladding light.
[0015] The beneficial effect of this utility model lies in the effective suppression of 1030nm ASE by utilizing the filtering effect of a tilted fiber Bragg grating (FBG). This patented technology utilizes a chirped tilted fiber Bragg grating (FBG) to suppress 1030nm ASE and self-excitation. The chirped tilted fiber Bragg grating (FBG) suppresses ASE and self-excitation in lasers. With a central wavelength of 1030nm and a bandwidth of 15nm or greater, it can filter out ASE and self-excitation lasers with a relatively wide bandwidth, resulting in a higher suppression capability for ASE and self-excitation. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 It is a structural diagram of the present utility model.
[0017] Figure 2 It is a schematic diagram of the inclined grating of the present utility model. DETAILED DESCRIPTION
[0018] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific implementation methods.
[0019] like Figure 1As shown, the utility model is a fiber laser based on a chirped tilted fiber Bragg grating, which is used to improve the 1018nm laser power output of the resonant cavity solution and suppress the generation of ASE and self-excitation.
[0020] A high-power 1018nm laser based on tilted fiber Bragg grating ASE / self-excited suppression includes a pump source 1, a first beam combiner 2, a second beam combiner 3, an active fiber 4, a high-reflection grating 5, a low-reflection grating 6, a tilted fiber Bragg grating 7, a stripper 8, and an output device 9.
[0021] from Figure 1 It can be seen that the pump source 1 adopts multiple pump light sources, including a forward pump light source and a reverse pump light source; preferably, the pump source 1 is preferably composed of a laser diode (LD) semiconductor laser or a fiber laser pump light source with a pump light operating wavelength of 915, 940nm or 976nm, wherein the output fiber of a single pump light source is 135 / 155 / 0.22, with an output power ≥600W, and there are 5 in total, 3 forward pump sources and 2 reverse pump sources.
[0022] Preferably, the first combiner 2 can be a forward 3*1 pump combiner; preferably, the pump fibers are 135 / 155 / 0.22, and the output fibers are 30 / 250 / 0.065. The pump fiber of the first combiner is connected to the pump source, the multiple pump fibers of the first combiner are connected to multiple pump light sources, and the output fiber of the first combiner is connected to the first end of the high-reflection grating 5.
[0023] The second end of the high-reflection grating 5 is connected to the first end of the active optical fiber 4 , the second end of the active optical fiber 4 is connected to the first end of the tilted fiber grating, and the second end of the tilted fiber grating is connected to the first end of the low-reflection grating 6 .
[0024] Preferably, the second combiner 3 can be an inverse (2+1)*1 combiner. Preferably, the pump fiber is 135 / 155 / 0.22, and the input and output signal fibers are 30 / 250 / 0.065. The pump fiber of the second combiner is connected to the pump source, the first end of the central fiber of the second combiner is connected to the second end of the low-reflection grating 6, the second end of the central fiber of the second combiner outputs the laser in the resonant cavity, the second end of the central fiber of the second combiner is connected to the first side of the stripper 8, the second side of the stripper is connected to the first side of the output device, and the second side of the output device is used to output the laser.
[0025] Preferably, the fiber type of the active optical fiber 4 is 30 / 250 / 0.065, the absorption coefficient is ≥2.5dB / m@915nm, and the fiber length is ≥5nm.
[0026] The high-reflection grating 5 preferably has a central wavelength of 1018 nm, a reflection bandwidth of 3 nm, and a reflectivity of ≥99.5%, and can be obtained by using a mask combined with femtosecond laser fiber core etching.
[0027] The low-reflection grating 6 preferably has a central wavelength of 1018nm, a reflection bandwidth of 1nm, and a reflectivity of 15%-5%; preferably, a reflectivity of 10%, which can be achieved by using a mask combined with femtosecond laser fiber core etching. Engineers realized that due to the wide bandwidth of the 1030nm ASE laser, it is difficult for conventional tilted gratings to fully couple the ASE laser. Preferably, see the attached Figure 2 The tilted grating preferably adopts a chirped tilted fiber Bragg grating. Preferably, the central wavelength of the chirped tilted fiber Bragg grating is 1030nm and the bandwidth is ≥15nm. It can be obtained by combining a mask with a femtosecond laser fiber core etching. The core etching obtains its characteristics of high transmittance for 1018nm core transmission, and the core laser near the 1030nm position of the core transmission is coupled to the cladding, thereby suppressing ASE and self-excited laser in the 1030nm band.
[0028] Preferably, the stripper 8 is of optical fiber type: 30 / 250 / 0.065, obtained by etching the optical fiber cladding with a CO2 laser.
[0029] Preferably, the output device 9 is an optical fiber of type 30 / 250 / 0.065, and has an internal stripper to strip the cladding light.
[0030] This solution can achieve >1500W of 1018nm fiber laser output with high ASE suppression. The 1030nm spectral component suppression ratio can reach over 60dB relative to the 1018nm laser.
[0031] exist Figure 1 In the above text, the first end refers to the left side, and the second end refers to the right side.
[0032] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are intended solely to illustrate the principles of the present invention and should not be construed in any way as limiting the scope of protection of the present invention. Based on the explanations herein, those skilled in the art will be able to devise other specific implementations of the present invention without inventive effort, and such implementations will fall within the scope of protection of the present invention.
Claims
1. A fiber laser based on a chirped tilted fiber Bragg grating, comprising a pump source, a first beam combiner, a second beam combiner, an active fiber, a high-reflection grating, a low-reflection grating, and a tilted fiber Bragg grating, characterized in that: The pump fiber of the first beam combiner is connected to the pump source, and the output fiber of the first beam combiner is connected to the first end of the high-reflection grating; the second end of the high-reflection grating is connected to the first end of the active fiber, the second end of the active fiber is connected to the first end of the tilted fiber Bragg grating, and the second end of the tilted fiber Bragg grating is connected to the first end of the low-reflection grating; the pump fiber of the second beam combiner is connected to the pump source, the first end of the central fiber of the second beam combiner is connected to the second end of the low-reflection grating, and the second end of the central fiber of the second beam combiner outputs the laser in the resonant cavity; the tilted fiber Bragg grating is a chirped tilted fiber Bragg grating, which is used for filtering and is used for ASE of the laser and suppression of self-excitation.
2. The fiber laser based on chirped tilted fiber Bragg grating according to claim 1, characterized in that: The central wavelength of the chirped tilted fiber Bragg grating is 1030 nm, and the bandwidth is greater than 15 nm.
3. The fiber laser based on chirped tilted fiber Bragg grating according to claim 1, characterized in that: It also includes a stripper and an output device. The second end of the central fiber of the second combiner is connected to the first side of the stripper, the second side of the stripper is connected to the first side of the output device, and the second side of the output device is used to output laser.
4. The fiber laser based on chirped tilted fiber Bragg grating according to claim 2, characterized in that: The laser output from the resonant cavity is an ytterbium-doped fiber co-band pump laser with a central wavelength less than 1030 nm.
5. The fiber laser based on chirped tilted fiber Bragg grating according to claim 4, characterized in that: The resonant cavity output is greater than 1500W of 1018nm fiber laser output.
6. The fiber laser based on chirped tilted fiber Bragg grating according to claim 5, characterized in that: The pump source adopts multiple pump light sources, including forward pump light sources and reverse pump light sources; the pump source adopts a laser diode semiconductor laser or a fiber laser pump light source with a pump light working wavelength of 915nm, 940nm or 976nm, wherein the output power of a single pump light source is greater than 600W.
7. The fiber laser based on chirped tilted fiber Bragg grating according to claim 6, characterized in that: The first combiner uses a forward 3*1 pump combiner, and the second combiner uses a reverse (2+1)*1 combiner.
8. The fiber laser based on chirped tilted fiber Bragg grating according to claim 4, characterized in that: The chirped tilted fiber Bragg grating is obtained by combining a mask with a femtosecond laser fiber core etching. The core etching obtains its characteristics of high transparency for 1018nm transmission of the fiber core, and the core laser at 1030nm position of the fiber core transmission is coupled into the cladding.
9. The fiber laser based on chirped tilted fiber Bragg grating according to claim 8, characterized in that: The fiber parameters of the pump fibers of the first and second combiners are 135 / 155 / 0.22, the fiber parameters of the center fiber are 30 / 250 / 0.065, and the length of the active fiber is greater than 5m.
10. The fiber laser based on chirped tilted fiber Bragg grating according to claim 9, characterized in that: The high-reflection grating has a central wavelength of 1018nm, a reflection bandwidth of 3nm, and a reflectivity of ≥99.5%. The low-reflection grating has a central wavelength of 1018nm, a reflection bandwidth of 1nm, and a reflectivity of 15%-5%. The output fiber type is 30 / 250 / 0.065, and it has an internal stripper to strip the cladding light. Compared with a 1018nm laser, the 1030nm spectral component suppression ratio is over 60dB.