Fiber laser

Abstract

This application discloses a fiber laser, relating to the field of laser technology. The fiber laser includes a light source emitting module, an amplification module, and a frequency doubling module. The amplification module is located at the output end of the light source emitting module, and the frequency doubling module is located at the output end of the amplification module. The light beam emitted by the light source emitting module is a first composite beam, which has a continuous mode and / or a pulsed mode. The first composite beam includes a continuous beam and / or a pulsed beam. The first composite beam is amplified by the amplification module and then frequency-doubled by the frequency doubling module to output a second composite beam. The fiber laser of this application can output a second composite beam, which has the characteristics of dual wavelengths and dual operating modes, enriching the application scope of fiber lasers.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser, in particular to a fiber laser. BACKGROUND

[0002] In the copper metal processing technology, the copper has a high reflectivity to the laser of 1um waveband, so the 532nm green light is needed to be used for processing. Since the existing pulse fiber laser has the fiber nonlinear limitation, the output green light laser power of the pulse fiber laser is limited, which limits the application of the pulse fiber laser. SUMMARY

[0003] Therefore, the present application provides a fiber laser to solve the problem of the limited green light output power of the pulse laser in the prior art, which limits the application of the pulse laser.

[0004] The present application provides:

[0005] A fiber laser, comprising:

[0006] A light source emitting module, the light beam emitted by the light source emitting module is a first composite light beam, the first composite light beam has a continuous mode and / or a pulse mode, and the first composite light beam comprises a continuous light beam and / or a pulse light beam;

[0007] An amplification module arranged at the output end of the light source emitting module, the amplification module comprises at least one first amplification unit, and the first amplification unit is used for amplifying the power of the first composite light beam;

[0008] A frequency doubling module arranged at the output end of the amplification module, the frequency doubling module comprises a frequency doubling crystal, and the frequency doubling crystal is used for converting the pulse light beam amplified by the amplification module into a second-harmonic pulse light beam.

[0009] In addition, the fiber laser according to the present application can also have the following additional technical features:

[0010] In some embodiments of the present application, the frequency doubling module further comprises a polarization unit, the polarization unit is arranged at the output end of the amplification module, the frequency doubling crystal is arranged at the output end of the polarization unit, and the polarization unit is used for rotating the polarization angle of the first composite light beam to a preset angle.

[0011] In some embodiments of the present application, the polarization unit comprises a half-wave plate and a first driving part, the half-wave plate is connected with the first driving part, the first driving part drives the half-wave plate to rotate, so as to change the angle of the included angle between the first composite light beam incident to the half-wave plate and the axis of the half-wave plate.

[0012] In some embodiments of the present application, the frequency doubling module further comprises a converging lens, which is arranged between the half-wave plate and the frequency doubling crystal, and used to converge the light beam emitted from the half-wave plate to the center of the frequency doubling crystal.

[0013] In some embodiments of the present application, the first amplification unit comprises a first unidirectional transmitter and a first polarization maintaining fiber amplifier, and the first polarization maintaining fiber amplifier is arranged at the output end of the first unidirectional transmitter.

[0014] In some embodiments of the present application, the amplification module further comprises a second amplification unit, which is arranged at the output end of the first amplification unit, and the second amplification unit comprises a second unidirectional transmitter and a power amplifier, and the power amplifier is arranged at the output end of the second unidirectional transmitter.

[0015] In some embodiments of the present application, the first unidirectional transmitter and the second unidirectional transmitter are both fiber-coupled isolators.

[0016] In some embodiments of the present application, the power amplifier is a second polarization maintaining fiber amplifier with a unidirectional or bidirectional pump source.

[0017] In some embodiments of the present application, the light source emission module is a single-mode semiconductor laser emission element.

[0018] In some embodiments of the present application, the frequency doubling crystal is a lithium triborate crystal.

[0019] Compared with the prior art, the present application has the following beneficial effects: the present application provides a fiber laser, wherein the light beam emitted by the light source emission module is a first composite light beam, and the first composite light beam has a continuous mode and / or a pulse mode, so that the first composite light beam contains a continuous light beam and / or a pulse light beam. By arranging the amplification module at the output end of the light source emission module and arranging the frequency doubling module at the output end of the amplification module, the first composite light beam is amplified by the amplification module and then output as a second composite light beam after frequency doubling by the frequency doubling module. In this way, the fiber laser of the present application can output a second composite light beam with double wavelengths and double working modes, thereby enriching the application of the fiber laser. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0021] Figure 1 Fig. 1 shows a structural schematic diagram of a fiber laser in some embodiments of the present application;

[0022] Figure 2 Fig. 2 shows a structural schematic diagram of an amplification module in some embodiments of the present application;

[0023] Figure 3 Fig. 3 shows a structural schematic diagram of a frequency doubling module in some embodiments of the present application;

[0024] Figure 4 Fig. 4 shows a mode diagram of a first composite light beam in some embodiments of the present application.

[0025] Main element symbol explanation:

[0026] 100-fiber laser; 110-light source emitting module; 120-amplification module; 121-first amplification unit; 1211-first unidirectional transmitter; 1212-first polarization maintaining fiber amplifier; 122-second amplification unit; 1221-second unidirectional transmitter; 1222-power amplifier; 123-third collimator; 130-frequency doubling module; 131-frequency doubling crystal; 132-first collimator; 133-polarization unit; 1331-half-wave plate; 1332-first driving part; 134-converging lens; 135-reflecting unit; 1351-dichroic mirror; 1352-second driving part; 136-second collimator; 137-light beam collector. DETAILED DESCRIPTION

[0027] Embodiments of the present application are described in detail below with reference to the accompanying drawings, in which examples of the embodiments are shown, and the same or similar notations or references denote the same or similar elements throughout. The embodiments described below by reference to the drawings are examples only, and are used only for the purpose of explaining the present application, and cannot be understood as limiting the present application.

[0028] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0030] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0031] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0032] like Figures 1 to 3 As shown, an embodiment of this application provides a fiber laser 100, primarily used to provide a second composite beam with dual wavelengths and dual operating modes. The fiber laser 100 includes a light source emitting module 110, an amplification module 120, and a frequency doubling module 130. The amplification module 120 is located at the output end of the light source emitting module 110, and the frequency doubling module 130 is located at the output end of the amplification module 120. The beam emitted by the light source emitting module 110 is a first composite beam, which has a continuous mode and / or a pulsed mode, thereby including a continuous beam and / or a pulsed beam.

[0033] Specifically, in this embodiment, the light source emitting module 110 adopts a single-mode semiconductor laser emitting element, such as a single-mode semiconductor laser. The continuous beam and pulsed beam of the first composite beam are both generated by the same single-mode semiconductor laser, thus ensuring that the continuous beam and pulsed beam emitted by the single-mode semiconductor laser have the same linear polarization state and spectral characteristics.

[0034] The single-mode semiconductor laser can output a first composite light beam. Adjusting the proportion of the direct current component of the single-mode semiconductor laser can adjust the mode of the first composite light beam, so that the proportion of the continuous light beam in the first composite light beam is 0%-100%, and the proportion of the pulsed light beam is 100%-0%. It can be understood that by adjusting the proportion of the continuous light beam and the pulsed light beam in the first composite light beam, the proportion of the high-power infrared light beam and the second-harmonic light beam in the second composite light beam can be adjusted.

[0035] Further, the first composite light beam has a mode as shown in Figure 4 Figure 4 Fig. (a) is a continuous mode diagram, Fig. (b) is a pulsed mode diagram, and Fig. (c) is a continuous and pulsed composite mode diagram. By adjusting the proportion of the direct current component of the light source emission module, the first composite light beam can have different modes. For example:

[0036] When the proportion of the direct current component is 0%, the mode of the first composite light beam is as shown in Fig. (b), and the proportion of the continuous light beam in the first composite light beam is 0%, and the proportion of the pulsed light beam is 100%.

[0037] When the proportion of the direct current component is 50%, the mode of the first composite light beam is as shown in Fig. (c), and the proportion of the continuous light beam in the first composite light beam is 50%, and the proportion of the pulsed light beam is 50%.

[0038] When the proportion of the direct current component is 100%, the mode of the first composite light beam is as shown in Fig. (a), and the proportion of the continuous light beam in the first composite light beam is 100%, and the proportion of the pulsed light beam is 0%.

[0039] It should be noted that in the present embodiment, the continuous light beam in the first composite light beam is continuous light of 1064 nm wavelength, and the pulsed light beam is pulsed light of 1064 nm wavelength and 1-30 ns pulse width. In other embodiments, the wavelength of the continuous light beam, the wavelength and pulse width of the pulsed light beam can be adjusted as required.

[0040] The amplification module 120 includes at least one first amplification unit 121 for amplifying the power of the first composite light beam; the frequency doubling module 130 includes a frequency doubling crystal 131 for converting the pulsed light beam amplified by the amplification module 120 into a second-harmonic pulsed light beam.

[0041] The continuous light beam in the first composite light beam is amplified by the amplification module 120, and since the continuous light beam is not limited by the nonlinearity of the frequency doubling crystal 131, it is difficult to be frequency-doubled, so the continuous light beam can output a high-power infrared light beam after being amplified by the amplification module 120; the pulsed light beam in the first composite light beam is first amplified by the amplification module 120 and then frequency-doubled by the frequency doubling module 130, and finally outputs a second-harmonic pulsed light beam, and the high-power infrared light beam and the second-harmonic pulsed light beam form a second composite light beam.​

[0042] Further, the frequency doubling crystal 131 is used to convert the amplified pulse light beam outputted by the amplification module 120 into a second harmonic pulse light beam. For example, the 1064 nm wavelength pulse light beam is converted into a 532 nm wavelength second harmonic pulse light beam after passing through the frequency doubling crystal 131. Since the peak power of the 1064 nm wavelength continuous light beam is low, it is difficult to be doubled by the frequency doubling crystal 131, and the 1064 nm wavelength continuous light beam is still outputted after passing through the frequency doubling crystal 131. In this way, the second composite light beam has the advantage of dual wavelength. In addition, since the first composite light beam has continuous and / or pulse modes, the second composite light beam also has continuous and / or pulse modes, which expands the application of the fiber laser 100.

[0043] In other embodiments, the light source emission module 110 is a Q-switched laser. The Q-switched laser can also support continuous and pulse modes of the first composite light beam, but the proportion of the continuous mode and the pulse mode in the first composite light beam cannot be adjusted, and the proportion of the high-power infrared light beam and the second harmonic pulse light beam in the second composite light beam needs to be adjusted by the frequency doubling module 130 to expand the application of the fiber laser 100.

[0044] Specifically, the frequency doubling module 130 further includes a first collimator 132, a polarization unit 133, a converging lens 134, a reflecting unit 135, a second collimator 136, and a beam collector 137.

[0045] The first collimator 132 collimates the light beam amplified by the amplification module 120 to maximize the coupling of the light beam outputted by the amplification module 120 into the polarization unit 133. The focal length of the first collimator 132 is 45 mm, NA=0.09, and the collimated light beam diameter is 1 mm.

[0046] The polarization unit 133 is arranged at the output end of the first collimator 132, and the frequency doubling crystal 131 is arranged at the output end of the polarization unit 133. The polarization unit 133 is used to rotate the polarization angle of the first composite light beam to a preset angle.

[0047] Specifically, the polarization unit 133 includes a half-wave plate 1331 and a first driving part 1332. The half-wave plate 1331 is connected with the first driving part 1332, and the first driving part 1332 drives the half-wave plate 1331 to rotate to change the angle of the included angle between the first composite light beam incident to the half-wave plate 1331 and the axis of the half-wave plate 1331. In this way, the polarization angle of the first composite light beam can be rotated to a preset angle according to actual needs, and the polarization state of the first composite light beam incident to the frequency doubling crystal 131 is adjusted to change the matching degree of the polarization state and the frequency doubling crystal, so that the proportion of the second harmonic pulse light beam in the second composite light beam is 0%-100%.

[0048] For example, when the included angle is 15°, the polarization angle is 30°, and the matching degree of the polarization angle to the frequency doubling crystal is cos 30°, the ratio of the second composite light beam to the frequency-doubled pulse light beam is 75%, and the ratio of the high-power infrared light beam is 25%.

[0049] When the included angle is 30°, the polarization angle is 60°, and the matching degree of the polarization angle to the frequency doubling crystal is cos 60°, the ratio of the second composite light beam to the frequency-doubled pulse light beam is 25%, and the ratio of the high-power infrared light beam is 75%.

[0050] When the included angle is 45°, the polarization angle is 90°, and the matching degree of the polarization angle to the frequency doubling crystal is cos 90°, the ratio of the second composite light beam to the frequency-doubled pulse light beam is 0%, and the ratio of the high-power infrared light beam is 100%.

[0051] The converging lens 134 is arranged between the half-wave plate 1331 and the frequency doubling crystal 131, and is used to converge the light beam emitted from the half-wave plate 1331 to the center of the frequency doubling crystal 131. The focal length of the converging lens 134 is 50 mm, and the antireflection film is 1030 nm-1080 nm.

[0052] In the embodiment, the frequency doubling crystal 131 is a lithium triborate crystal. It can be understood that lithium triborate (LiB3O5, LBO) is a nonlinear medium, and the transmission of light waves in the nonlinear medium is essentially a process of electromagnetic field interacting with the nonlinear medium, and the nonlinear medium generates a corresponding induced polarization field. The properties of the induced polarization field are mainly determined by the electromagnetic field. There are two cases of electromagnetic field propagation in the nonlinear medium, namely linear propagation and nonlinear propagation. The two propagation modes generate corresponding induced polarization fields. When the intensity of the propagating light field is weak, the induced polarization field generated in the nonlinear medium is linear, and there is no interaction between the electromagnetic fields and the medium, and the emitted light and the incident light maintain a linear relationship; when the intensity of the propagating light field is strong, the induced polarization field of the nonlinear medium exhibits nonlinear properties, and the emitted light and the incident light no longer maintain a simple linear relationship, and energy exchange occurs between the electromagnetic fields, generating a light field of a new frequency.

[0053] Optionally, the size of the frequency doubling crystal is 3 mm x 3 mm x 20 mm.

[0054] The reflection unit 135 is arranged at the output end of the frequency doubling crystal 131, and the reflection unit 135 includes a dichroic mirror 1351 and a second driving part 1352. The dichroic mirror 1351 is connected to the second driving part 1352, and the second driving part 1352 drives the dichroic mirror 1351 to insert into the light path or move out of the light path. The dichroic mirror 1351 can transmit a 532 nm wavelength light beam and reflect a 1064 nm wavelength light beam.

[0055] When the second driving unit 1352 drives the dichroic mirror 1351 to be inserted into the optical path, the high-power infrared beam in the second composite beam is reflected, and the second-harmonic pulse beam is transmitted. The reflected high-power infrared beam is absorbed by the beam collector 137, and the transmitted second-harmonic pulse beam is output after passing through the second collimator 136. At this time, the output second composite beam contains only the second-harmonic pulse beam.

[0056] When the second driving unit 1352 drives the dichroic mirror 1351 to move out of the optical path, the high-power infrared beam is not reflected, and the second composite beam is output after passing through the second collimator 136. At this time, the second composite beam contains a high-power infrared beam and a second-harmonic pulse beam.

[0057] It is not difficult to conclude from the foregoing that the reflection unit 135, by adjusting whether there is a high-power infrared beam in the second composite beam, thereby changes the ratio of the high-power infrared beam and the second harmonic composite beam in the second composite beam.

[0058] The beam collector 137 is used to collect the high-power infrared beam reflected by the dichroic mirror 1351.

[0059] The second collimator 136 is used to collimate the second composite beam. The focal length of the second collimator 136 is 200mm, NA=0.095, and the diameter of the collimated beam is 2.5mm.

[0060] In addition, the first collimator 132, the half-wave plate 1331, the converging lens 134, the dichroic mirror 1351, and the second collimator 136 are arranged coaxially in sequence to improve the quality of the second composite beam.

[0061] It is understood that the polarization unit 133 in the frequency doubling module 130 can adjust the ratio of the high-power infrared beam and the second-harmonic pulse beam in the second composite beam. The reflection unit 135 can adjust whether the second composite beam contains a high-power infrared beam. In this way, the ratio of the high-power infrared beam and the second-harmonic beam in the second composite beam can be adjusted according to actual production needs, further expanding the application scope of the fiber laser 100.

[0062] In this embodiment, the first amplification unit 121 is connected to the output end of the light source emitting module 110. Each first amplification unit 121 includes a first unidirectional transmitter 1211 and a first polarization-maintaining fiber amplifier 1212, with the first polarization-maintaining fiber amplifier 1212 located at the output end of the first unidirectional transmitter 1211. The first unidirectional transmitter 1211 is a fiber optic coupling isolator, which enables unidirectional beam transmission and prevents reflected light from connectors, end faces, etc., in the optical path from returning and affecting the stability of the output beam.

[0063] When there are multiple first amplification units 121, the multiple first amplification units 121 are arranged along the transmission direction of the first composite beam, and adjacent first amplification units 121 are connected. In this way, the first amplification units 121 pre-amplify the first composite beam.

[0064] Since the power obtained by the multiple first amplification units 121 may not reach the power requirement for frequency doubling, the amplification module 120 also includes a second amplification unit 122. The first amplification unit 121 first amplifies the first composite beam emitted by the light source emitting module 110 by a certain power, and then the second amplification unit 122 amplifies the first composite beam to the required power. In other embodiments, the amplification module 120 may also include more amplification units, which can be selected according to actual conditions during specific implementation.

[0065] The second amplification unit 122 is located at the output end of the first amplification unit 121. The second amplification unit 122 includes a second unidirectional transmitter 1221 and a power amplifier 1222. The power amplifier 1222 is located at the output end of the second unidirectional transmitter 1221.

[0066] The second unidirectional transmitter 1221 is an optical fiber coupling isolator, which enables unidirectional beam transmission and prevents reflected light from connectors, end faces, etc., in the optical path from returning and affecting the stability of the output beam. The power amplifier 1222 is a second polarization-maintaining fiber amplifier with a unidirectional or bidirectional pump source. The second polarization-maintaining fiber amplifier uses a large-mode-field polarization-maintaining fiber and related pump coupling devices. Nonlinear effects are suppressed by shortening the cavity length using high-absorption large-mode-field fiber, and the beam quality of the signal light is improved by adjusting parameters such as the cutting tension, blade polishing, and fusion discharge during large-mode-field fiber splicing.

[0067] In this embodiment, the amplification module 120 further includes a third collimator 123, which is used to collimate the light beam amplified by the first amplification unit 121 and the second amplification unit 122.

[0068] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0069] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A fiber laser, characterized in that, include: A light source emitting module emits a first composite beam, which has a continuous mode and a pulsed mode. The first composite beam includes a continuous beam and a pulsed beam, and the continuous beam and the pulsed beam have the same linear polarization state. An amplification module is disposed at the output end of the light source emitting module. The amplification module includes at least one first amplification unit, which is used to amplify the power of the first composite beam. A frequency doubling module is located at the output end of the amplification module. The frequency doubling module includes a frequency doubling crystal, which is used to convert the pulse beam amplified by the amplification module into a second-harmonic pulse beam. The frequency doubling module further includes a polarization unit, which is located at the output end of the amplification module. The frequency doubling crystal is located at the output end of the polarization unit. The polarization unit is used to rotate the polarization angle of the first composite beam to a preset angle. The polarization unit includes a half-wave plate and a first driving unit. The half-wave plate is connected to the first driving unit, and the first driving unit drives the half-wave plate to rotate, thereby changing the angle formed between the first composite beam incident on the half-wave plate and the axis of the half-wave plate.

2. The fiber laser according to claim 1, characterized in that, The frequency doubling module also includes a converging lens, which is disposed between the half-wave plate and the frequency doubling crystal, and is used to converge the light beam emitted from the half-wave plate to the center of the frequency doubling crystal.

3. The fiber laser according to claim 1, characterized in that, The first amplification unit includes a first unidirectional transmitter and a first polarization-maintaining fiber amplifier, wherein the first polarization-maintaining fiber amplifier is located at the output end of the first unidirectional transmitter.

4. The fiber laser according to claim 3, characterized in that, The amplification module further includes a second amplification unit, which is located at the output end of the first amplification unit. The second amplification unit includes a second unidirectional transmitter and a power amplifier, with the power amplifier located at the output end of the second unidirectional transmitter.

5. The fiber laser according to claim 4, characterized in that, Both the first unidirectional transmitter and the second unidirectional transmitter are fiber optic couplers.

6. The fiber laser according to claim 4, characterized in that, The power amplifier is a second polarization-maintaining fiber amplifier with a unidirectional or bidirectional pump source.

7. The fiber laser according to claim 1, characterized in that, The light source emitting module is a single-mode semiconductor laser emitting element.

8. The fiber laser according to any one of claims 1 to 7, characterized in that, The frequency doubling crystal is a lithium triborate crystal.

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