Control method for a fiber laser device and fiber laser device

Abstract

A control method for a fiber laser device (1000) and a fiber laser device (1000) are disclosed. The fiber laser device (1000) comprises a fiber laser generator (1), wherein the fiber laser generator (1) comprises a pump source (11), a plurality of light signal detection devices (2), a device for checking relative laser intensity (3), and a control device (4).The control method for the fiber laser device (1000) comprises the following steps: acquiring a start command; upon receiving the start command, controlling the fiber laser generator (1000) to operate so that laser light is output; acquiring a laser wavelength signal and a wavelength signal of stimulated Raman scattered light in an output laser light, which are detected by the plurality of light signal detecting devices (2); calculating a relative intensity depending on the laser wavelength signal and the wavelength signal of stimulated Raman scattered light in the output laser light; controlling, depending on a relationship between the relative intensity and a set threshold value, the fiber laser generator to regulate a wavelength and an output power of a laser light output by the pump source (11) or to stabilize it in a current operating state.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from Chinese patent application No. 202311322211.2 filed on October 12, 2023, the entire contents of which are incorporated by reference into this application. TECHNICAL FIELD

[0002] The present application relates to the field of laser technology, in particular to a control method for a fiber laser device and a fiber laser device. STATE OF THE ART

[0003] Fiber lasers are widely used in industrial manufacturing, national defense, scientific research, and many other fields due to their small size, compact design, easy thermal management, maintenance-free all-fiber structure, good beam quality, and high power. With the widespread application of fiber lasers in cutting, increasingly stringent requirements for laser output power and brightness are being placed on the pursuit of cutting efficiency. Stimulated Raman scattering (SRS) in fibers is the main factor limiting the output power and brightness of fiber lasers. The occurrence of SRS in fibers not only affects the stability of the laser but can also damage it. CONTENT OF THE PRESENT INVENTION

[0004] The main object of the present application is to provide a control method for a fiber laser device and a fiber laser device capable of automatically suppressing the stimulated Raman scattering effect.

[0005] In order to achieve the above-mentioned object, the present application proposes a control method for a fiber laser device, wherein the fiber laser device comprises an electrically connected fiber laser generator, wherein the fiber laser generator comprises a pump source, a plurality of light signal detection devices, a device for checking relative laser intensity and a control device, wherein the control method for the fiber laser device comprises the following steps: Acquiring a start command; Controlling, upon receiving the start command, the fiber laser generator to operate so that a laser light is output;

[0006] Acquiring a laser wavelength signal and a wavelength signal of stimulated Raman scattered light in an output laser light detected by the plurality of light signal detecting devices;

[0007] Calculating a relative intensity depending on the laser wavelength signal and the wavelength signal of the stimulated Raman scattered light in the output laser light;

[0008] Controlling, depending on a relationship between the relative intensity and a set threshold, the fiber laser generator to regulate a wavelength and an output power of a laser light emitted by the pump source or to stabilize it in a current operating state.

[0009] In one embodiment, the step of “controlling, depending on a relationship between the relative intensity and a set threshold value, the fiber laser generator to regulate a wavelength and an output power of a laser light emitted by the pump source or to stabilize it in a current operating state” comprises: Controlling the fiber laser generator to regulate the wavelength and output power of the laser light emitted by the pump source when a current relative intensity is below the set threshold; Acquiring an output laser light intensity in a controlled output laser light detected by the plurality of light signal detecting devices, and calculating a controlled relative intensity; Comparing the output laser light intensity before control with the output laser light intensity before control and calculating a change value of the laser light output intensity;

[0010] Controlling the fiber laser device to stabilize at a current wavelength and a current output power of the laser light output by the pump source when the controlled relative intensity is greater than or equal to the set threshold and the change value of the laser light output intensity is within a preset range;

[0011] Repeating the above step of controlling the fiber laser generator to control a wavelength and an output power of the laser light output by the pump source when the controlled relative intensity is below the set threshold.

[0012] In one embodiment, the preset range is between -0.5% and 0.5%.

[0013] In one embodiment, the control method further comprises, after the step “calculating a relative intensity depending on the laser wavelength signal and the wavelength signal of the stimulated Raman scattered light in the output laser light”: Acquiring a relative measurement intensity of the output laser light measured by the relative laser intensity testing device; Controlling, depending on the relative measurement intensity, a light transmittance of the light signal detection devices in order to correct the relative intensity until a current relative intensity is equal to the relative measurement intensity.

[0014] The present application further proposes a fiber laser device comprising: a fiber laser generator for outputting a laser light; a plurality of light signal detecting devices disposed within the fiber laser generator and used to detect a laser wavelength signal, a wavelength signal of stimulated Raman scattered light, and a value of an output laser light intensity in an output laser light of the fiber laser generator; a relative laser intensity test device used to measure a relative measurement intensity of the output laser light of the fiber laser generator; and a control device electrically connected to the fiber laser generator, the plurality of light signal detection devices, and the relative laser intensity testing device, the control device comprising a memory, a processor, and a fiber laser device control program stored on the memory and executable on the processor, the fiber laser device control program being configured to implement the steps of the fiber laser device control method described above.

[0015] In one embodiment, it is provided that each of the light signal detection devices comprises: an optical power transmission fiber for providing a signal of the output laser light; a hollow body, wherein an interior of the hollow body is spherically shaped, wherein an outer surface of the hollow body is provided with a through hole and a light-transmitting hole which are arranged at a distance from each other, wherein the through hole is provided for the passage of the optical energy transmission fiber, wherein an aperture adjusting device is provided at the light-transmitting hole; a filter arranged at the light-transmitting hole; and a photodetector arranged on the filter and used to detect a laser light signal emerging from the light-transmitting hole and passing through the filter, and to convert the laser light signal into an electrical signal and transmit it to the control device.

[0016] In one embodiment, the device for testing relative laser intensity is a spectrum analyzer used to measure a relative measurement intensity of the output laser light.

[0017] In one embodiment, the fiber laser device comprises: two pump sources comprising a forward pump source and a reverse pump source, and used to provide a laser light source; two pump light couplers, each comprising a double-clad fiber, wherein an inner cladding of the two double-clad fibers is coupled to the forward pump source and the reverse pump source, respectively; a fiber laser resonator, each end of which is connected to a fiber of the respective pump light coupler; two cladding light strippers comprising a first stripper and a second stripper, one end of the first stripper being electrically connected to the reverse pumping source and the other end of the first stripper being connected to the second stripper, the light signal detection means performing spatial optical signal detection between the first stripper and the second stripper; and a laser output head connected to the second stripper and used to connect to a laser processing head and output a laser light.

[0018] In one embodiment, it is provided that each of the pump sources comprises: a pump semiconductor laser chip for converting electrical energy into a divergent laser output; a heat sink device for dissipating heat from the pump semiconductor laser chip; a collimating lens arranged on one side of the pump semiconductor laser chip and used to collimate a divergent laser light output by the pump semiconductor laser chip into parallel light; a volume grating arranged on a side of the collimating lens remote from the pump semiconductor laser chip and used to control a laser wavelength of the pump semiconductor laser chip; a focusing lens arranged on a side of the volume grating remote from the pump semiconductor laser chip and used to focus the laser light output from the pump semiconductor laser chip; a fiber end cap arranged on a side of the focusing lens remote from the pump semiconductor laser chip, wherein a focus of a focused beam converges at the fiber end cap; and a pump light output fiber arranged on a side of the fiber end cap remote from the pump semiconductor laser chip and used to output a pump laser light.

[0019] In one embodiment, it is provided that a piezoceramic or a temperature control plate is arranged on the volume grid.

[0020] In the technical solution of the present application, after receiving the start command, the fiber laser generator is controlled to operate and output laser light. When the output power of the output laser light reaches a certain intensity, the stimulated Raman scattering effect in the fiber affects the output power and brightness of the output laser light. Therefore, the plurality of light signal detecting devices detect the laser wavelength signal and the wavelength signal of the stimulated Raman scattered light in the output laser light, and the relative intensity is calculated depending on the detected laser wavelength signal and the detected wavelength signal of the stimulated Raman scattered light in the output laser light. If the relative intensity is below the set threshold, this indicates that the stimulated Raman scattering effect is affecting the stability of the fiber laser device.Therefore, the wavelength and output power of the laser light output from the pump source of the fiber laser generator are controlled by the controller, thereby reducing the influence of the stimulated Raman scattering effect on the fiber laser device while ensuring that the output power remains stable within a certain value range, thereby improving the operating stability of the fiber laser device. SHORT DESCRIPTION OF THE DRAWING

[0021] In order to more clearly illustrate the technical solutions in the embodiments or the prior art of the present application, the accompanying drawings to be used in the description of the embodiments or the prior art are briefly introduced below, and it is obvious that the accompanying drawings in the following description are only some of the embodiments of the present application, and that for the person with ordinary knowledge in the field, other drawings can be obtained based on the structures shown in the drawings without creative work. Fig. 1 shows a schematic structural view of an embodiment of a fiber laser device according to the present application; Fig. 2 shows a schematic structural view of a light signal detection device from Fig. 1; Fig. 3 shows a schematic structural view of a fiber laser generator from Fig. 1; Fig. 4 shows a comparison diagram between a wavelength signal of an output laser light and a wavelength signal of a stimulated Raman scattered light. List of reference symbols: 1000 fiber laser device 1 fiber laser generator 11 Pump source 132 Yb-doped double-clad fiber low- 133 reflective fiber grating 14 Mantle Light Strippers 111 pump semiconductor laser chip; 112 Heat sink device 113 Collimating lens 114 volume grids 1141 Piezoceramic 1142 Temperature control plate 115 Focusing lens 116 Fiber end cap 117 Pump light output fiber 12 pump light couplers 13 Fiber laser resonator highly reflective 131 fiber gratings 141 first stripper 142 second stripper 15 Laser output head 2 Light signal detection device 21 optical energy transmission fiber 22 hollow bodies 222 translucent hole 223 Aperture adjustment device 23 filters 24 photodetector 3 Device for testing relative laser intensity 4 Control device

[0022] The realization of the purpose of the present application, the functional features and the advantages are described in more detail in connection with the embodiments and with reference to the accompanying drawings. Detailed embodiments

[0023] The technical solutions in the embodiments of the present application are described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present application. It is understood that the described embodiments represent only a part of the embodiments of the present application and not all embodiments. Starting from the embodiments in the present application, all other embodiments achieved by a person with ordinary skill in the art without creative work fall within the scope of the present application.

[0024] It should be noted that all directional terms (such as up, down, left, right, forward, back ......) in the embodiments of the present application are only used to explain the relative positional relationship, movement, etc. between the components in a specific posture (as shown in the attached drawings), and the directional terms will be changed accordingly when the specific posture is changed.

[0025] Furthermore, the terms "first," "second," etc., are used in this application for descriptive purposes only and are not to be understood as an indication of their relative importance or as an implicit statement of the number of technical features specified. Consequently, a feature defined as "first" or "second" may include at least one such feature, either explicitly or implicitly. Furthermore, the technical solutions of the various embodiments may be combined with each other, but only on the basis that they can be achieved by a person with ordinary skill in the art. If the combination of technical solutions is contradictory or unattainable, it should be assumed that the combination of such technical solutions does not exist and does not fall within the scope of the present application.

[0026] Fiber lasers are widely used in industrial manufacturing, national defense, scientific research, and many other fields due to their small size, compact design, easy thermal management, maintenance-free all-fiber structure, good beam quality, and high power. With the widespread application of fiber lasers in cutting, increasingly stringent requirements for laser output power and brightness are being placed on the pursuit of cutting efficiency. Stimulated Raman scattering (SRS) in fibers is the main factor limiting the output power and brightness of fiber lasers. The occurrence of SRS in fibers not only affects the stability of the laser but can also damage it.

[0027] To solve the above problems, the present application proposes a control method for a fiber laser device and a fiber laser device. Fig. 1 to 4 illustrate schematic structural views of an embodiment of the control method for the fiber laser device and the fiber laser device according to the present application.

[0028] With reference to Fig. 1, the present application proposes a fiber laser device 1000, wherein the fiber laser device 1000 comprises an electrically connected fiber laser generator 1, a plurality of light signal detection devices 2, a relative laser intensity test device 3, and a control device 4, wherein the fiber laser generator 1 is used to output a laser light, wherein the plurality of light signal detection devices 2 are used to detect a laser wavelength signal, a wavelength signal of stimulated Raman scattered light, and an output laser light intensity value in an output laser light of the fiber laser generator 1, wherein the relative laser intensity test device 3 is used to measure a relative measurement intensity of the output laser light of the fiber laser generator 1, and wherein the control device 4 is electrically connected to the fiber laser generator 1,the plurality of light signal detection devices 2 and the device for testing relative laser intensity 3, wherein the control device 4 comprises a memory, a processor, and a control program 1000 stored in the memory and executable on the processor, wherein the control program of the fiber laser device 1000 is configured to implement the steps of the control method for the fiber laser device 1000.

[0029] In the technical solution of the present application, after receiving the start command, the fiber laser generator 1 is controlled to operate and output laser light. When the output laser light output power reaches a certain intensity, the stimulated Raman scattering effect in the fiber affects the output laser light output power and brightness. Therefore, the plurality of light signal detecting devices 2 detect the laser wavelength signal and the wavelength signal of the stimulated Raman scattered light in the output laser light, and the relative intensity is calculated based on the detected laser wavelength signal and the detected wavelength signal of the stimulated Raman scattered light in the output laser light. At the same time, the relative intensity is detected by the relative laser intensity checking device 3 to obtain a relative measurement intensity.Using the relative measurement intensity, the calculated relative intensity is corrected so that it is equal to the relative measurement intensity. The corrected relative intensity is then compared with a set threshold. If the corrected relative intensity is below the set threshold, this indicates that the stimulated Raman scattering effect is affecting the stability of the fiber laser device 1000. Therefore, the wavelength and output power of the laser light output from the pump source 11 of the fiber laser generator 1 are controlled by the controller 4, thereby reducing the influence of the stimulated Raman scattering effect on the fiber laser device 1000 while ensuring that the output power remains stable within a certain value range, thereby improving the operational stability of the fiber laser device 1000.

[0030] In order to better capture the laser wavelength and the wavelength of stimulated Raman scattered light in the output laser, with reference to Fig. 2 Each of the light signal detection devices 2 includes an optical energy transmission fiber 21, a hollow body 22, a filter 23, and a photodetector 24. The optical energy transmission fiber 21 is used to provide a signal of the output laser light. An interior of the hollow body 22 is spherically shaped, and an outer surface of the hollow body 22 is provided with a through-hole and a light-transmitting hole 222 arranged at a distance from each other. The through-hole is provided for the passage of the optical energy transmission fiber 21. An aperture adjustment device 223 is provided at the light-transmitting hole 222. The filter 23 is arranged at the light-transmitting hole 222.The photodetector 24 is arranged on the filter 23 and is used to detect a laser light signal emerging from the light-transmitting hole 222 and passing through the filter, converting the laser light signal into an electrical signal, and transmitting it to the control device 4. Specifically, the power transmission optical fiber 21 is connected to the fiber laser generator to receive the laser light generated by this fiber laser generator. In the solution of the present application, the interior of the hollow body 22 may have a regular shape, such as a sphere or an ellipsoid, but not limited thereto. The interior of the hollow body 22 can evenly distribute the laser light signal emitted by the power transmission optical fiber 21 and the stimulated Raman scattered light signal within the interior, thereby ensuring the stability of the light signal output from the light-transmitting hole 222.It is understood that the light-transmitting hole 222 is arranged in the center of the upper end surface of the hollow body 22. The light-transmitting hole 222 can be circular. An aperture adjusting device 223 is arranged at the light-transmitting hole 222. In particular, the aperture adjusting device 223 can be a flange device. The aperture adjusting device 223 and the light-transmitting hole 222 cooperate to regulate the amount of light transmittance and thus control the intensity of the transmitted light signal. Furthermore, a filter 23 is arranged at the light-transmitting hole 222. The filter 23 is an optical filter 23 with wavelength selectivity, thus retaining the laser light signal required for the present application and the stimulated Raman scattered light signal, and filtering out the influence of scattered light in other bands.After receiving the required laser light signal and the stimulated Raman scattered light signal, the photodetector 24 converts the light signal into a current or voltage signal and transmits it to the control device 4.

[0031] In addition, in order to ensure the accuracy of the relative laser intensity correction, the relative laser intensity checking device 3 is a spectrum analyzer used to measure a relative measurement intensity of the output laser light, wherein after comparing the relative measurement intensity with the calculated relative intensity, the light signal detecting device is adjusted to ensure that the calculated relative intensity agrees with the relative measurement intensity, thereby completing the relative laser intensity correction.

[0032] With reference to Fig. 1, in one embodiment of the present application, the fiber laser device 1 comprises two pump sources 11, two pump light couplers 12, a fiber laser resonator 13, two cladding light strippers 14, and a laser output head 15. In the present embodiment, the two pump sources 11 comprise a forward pump source 11 and a reverse pump source 11, wherein the pump sources 11 are used to provide a laser light source; wherein the two pump light couplers 12 each comprise a double-clad fiber, wherein an inner cladding of the two double-clad fibers is connected to the forward pump source 11 orthe reverse pump source 11, wherein two ends of the fiber laser resonator 13 are each connected to a fiber of the respective pump light coupler 12, wherein the two cladding light strippers 14 comprise a first stripper 141 and a second stripper 142, wherein one end of the first stripper 141 is electrically connected to the reverse pump source 11 and the other end of the first stripper 141 is connected to the second stripper 142, wherein the light signal detection device 2 performs spatial optical signal detection between the first stripper 141 and the second stripper 142, and wherein the laser output head 15 is connected to the second stripper 142 and is used for connection to a laser processing head and for outputting a laser light.

[0033] The pump source 11 is a semiconductor fiber output pump source 11. In the present application, the pump source 11 comprises a group of forward pump sources 11 and a group of backward pump sources 11, wherein the forward pump sources 11 are connected to one of the pump light couplers 12, wherein the pump light coupler 12 is in turn connected to one end of the fiber laser resonator 13, wherein the other end of the fiber laser resonator 13 is connected to another of the pump light couplers 12, which is connected to the backward pump sources 11. In particular, the pump source 11 has a wavelength range of 900 nm to 1000 nm, wherein the semiconductor output fiber has a core diameter of 100 µm to 220 µm and a numerical aperture range of 0.15 to 0.22 to enable power supply of a resonant cavity and a gain medium.The pump light coupler 12 is used to couple the multiple pump sources 11 into the inner cladding of the double-clad fiber. In particular, a coupling mode of (6+1)×1 or (18+1)×1 can be used.

[0034] Furthermore, the fiber laser resonator 13 resonantly amplifies the wavelength of the pump source 11 to the wavelength of the output laser light, with the wavelength of the output laser light being in the range of 1030 nm to 1090 nm. The fiber laser resonator 13 consists of a highly reflective fiber grating 131, a pair of low-reflective fiber gratings 133, and a Yb-doped double-clad fiber 132. More specifically, the highly reflective fiber grating 131 and the low-reflective fiber grating 133 are double-clad fiber Bragg gratings or chirped fiber gratings. Furthermore, the double-clad fiber has a core diameter of 20 µm to 30 µm and a numerical aperture of 0.04 to 0.07, with the inner cladding having a diameter of 350 µm to 600 µm and a numerical aperture of 0.4 to 0.5, with the central wavelength range of the fiber grating being between 1030 nm and 1090 nm.The high-reflectivity fiber grating 131 has a reflectivity of more than 99% and a 3 dB bandwidth from 2 nm to 3 nm, while the low-reflectivity fiber grating 133 has a reflectivity of 10% ± 5% and a 3 dB bandwidth from 1 nm to 1.5 nm. It is particularly important to note that when using a chirped fiber grating, the connection direction must be considered. The Yb-doped double-clad fiber serves to provide population inversion to realize the amplification of the output laser light. The Yb-doped double-clad fiber has a core diameter of 20 µm to 30 µm, a numerical aperture of 0.04 to 0.07, the inner cladding has a diameter of 350 µm to 600 µm and a numerical aperture of 0.4 to 0.5, and the absorption of the pump wavelength is 0.3 dB / m to 1.5 dB / m.The fiber laser resonator 13 is connected to the first stripper 141 for stripping the cladding laser light generated in the fiber laser resonator 13 and the remaining cladding pump light. The other end of the first stripper 141 is electrically connected to one end of the light signal detector 2, and the second stripper 142 is electrically connected to the other end of the light signal detector 2. The second stripper 142 serves to strip the light returning from the processing output to prevent the returning light from affecting the measurement accuracy of the light signal detector 2. A laser output head 15 is connected downstream of the second stripper 142, which interacts with the laser processing head to process the material. The laser output head 15 can also be configured with a standard interface such as QCS, QBH, or QD to connect to the laser processing head, but this is not limited here.

[0035] Reference is made to Fig.3. To adjust the output power and wavelength of the fiber laser generator 1, the pump source 11 must be controlled. Therefore, in the present application, each of the pump sources 11 comprises a pump semiconductor laser chip 111, a heat sink device 112, a volume grating 114, a focusing lens 115, a fiber end cap 116, and a pump light output fiber 117. The pump semiconductor laser chip 111 is used to convert electrical energy into a divergent laser output. The heat sink device 112 is arranged annularly around the outside of the pump semiconductor laser chip 111 and is used to dissipate heat from the pump semiconductor laser chip 111. The collimation lens 113 is arranged on one side of the pump semiconductor laser chip 111 and is used to collimate a divergent laser light output by the pump semiconductor laser chip 111 into parallel light, which facilitates the wavelength control by the volume grating 114.The volume grating 114 is arranged on a side of the collimating lens 113 remote from the pump semiconductor laser chip 111 and is used to control a laser wavelength of the pump semiconductor laser chip 111. The focusing lens 115 is arranged on a side of the volume grating 114 remote from the pump semiconductor laser chip 111 and is used to focus the laser light output from the pump semiconductor laser chip 111. The fiber end cap 116 is arranged on a side of the focusing lens 115 remote from the pump semiconductor laser chip 111. The fiber end cap 116 can increase the light-receiving area of ​​the fiber end face, reduce the energy density of the fiber end face, and prevent the fiber end face from burning out due to excessive energy density. A focus of a focused beam converges at the fiber end cap 116.The pump light output fiber 117 is arranged on a side of the fiber end cap 116 remote from the pump semiconductor laser chip 111 and is used to output pump laser light. Furthermore, the pump semiconductor laser chip 111 is connected to a constant-current driver board. The controller 4 can regulate the constant-current driver board and thus control the power of the laser light output from the pump semiconductor laser chip 111.

[0036] In one embodiment, a piezoceramic 1141 or a temperature control plate 1142 is arranged on the volume grating 114 to adjust the wavelength of the output laser light. In one embodiment of the present application, the piezoceramic 1141 or the temperature control plate 1142 is arranged symmetrically to the volume grating 114. The piezoceramic 1141 can regulate the stress exerted on the volume grating 114 by changing the voltage, while the temperature control plate 1142 can regulate the temperature of the volume grating 114 by changing the current. With changes in stress and temperature, the volume grating 114 changes its effective refractive index in the grating region, thereby changing the central wavelength of refraction of the volume grating 114 and thus controlling the output wavelength.

[0037] The control device 4 comprises a memory, a processor and a control program of the fiber laser device 1000, which is stored on the memory and executable on the processor, wherein the control program of the fiber laser device 1000 is configured to implement the steps of the control method for the fiber laser device 1000.|

[0038] The control device 4 can comprise a processor, e.g., a central processing unit (CPU), a communication bus, a user interface, a network interface, and a memory. The communication bus serves to implement the connection or communication between these components. The user interface can comprise a screen (display), an input unit such as a keyboard. The user interface can also comprise standard wired interfaces and wireless interfaces. The network interface can comprise standard wired interfaces and wireless interfaces, such as a wireless fidelity (Wi-Fi) interface. The memory can be a high-speed random access memory (RAM) or a stable non-volatile memory (NVM), e.g., a disk drive.The memory may also be a storage device independent of the aforementioned processor.

[0039] Those skilled in the art will understand that the control device 4 may include more or fewer components than those described above, or may combine certain components or have other component arrangements.

[0040] In the control device 4, the network interface is primarily used for data communication with other devices, while the user interface is primarily used for data interaction with a user. In the present application, the processor and memory can be arranged in the control device 4. The control device 4 calls the control program of the fiber laser device 1000 stored in the memory via the processor and executes the steps of the control method for the fiber laser device 1000 according to the present embodiment. Specifically, the control device 4 executes at least the following steps: Acquiring a start command; Controlling, upon receiving the start command, the fiber laser generator 1 to operate so that a laser light is output; Acquiring a laser wavelength signal I XL and a wavelength signal of stimulated Raman scattered light I λSRSin the output laser light detected by the plurality of light signal detecting devices 2;

[0041] Calculating a relative intensity depending on the laser wavelength signal I λL and the wavelength signal of the stimulated Raman scattered light I λSRS in the output laser light;

[0042] Controlling, depending on a relationship between the relative intensity and a set threshold value, the fiber laser generator 1 to regulate a wavelength and an output power of a laser light output by the pump source 11 or to stabilize it in a current operating state.

[0043] Embodiments of the present application provide a control method for a fiber laser device 1000 comprising the following steps: S10: Acquiring a start command.

[0044] During operation of the fiber laser device 1000, the influence of the stimulated Raman scattering effect also increases with gradually increasing output power and brightness. The start command mentioned here is a start signal received when the fiber laser device 1000 starts operating, which is, for example, a power-on signal from a power source or a switching signal, etc., which is not limited here.

[0045] S20: Control, after receiving the start command, the fiber laser generator 1 to operate so that a laser light is output.

[0046] Depending on the start command, the fiber laser generator 1 starts operating, activating the pump source 11 to provide a laser light source.

[0047] S30: Acquiring a laser wavelength signal I λL and a wavelength signal of stimulated Raman scattered light I λSRSin the output laser light detected by the plurality of light signal detecting devices 2;

[0048] In the technical solution of the present application, a laser light signal and a stimulated Raman scattered light signal are generated during operation of the fiber laser device 1000. When the stimulated Raman scattering effect occurs, the energy of the laser wavelength is transferred to the stimulated Raman scattering wavelength.

[0049] In a fiber, the following relationship exists between the stimulated Raman light wavelength and the laser wavelength: ΔU=CλL2Δλ

[0050] Where Δ U for a frequency shift produced by the stimulated Raman light relative to the laser light in a quartz fiber, this frequency shift depending on the fiber material, where in the quartz fiber Δ U is about 13 THz, where C is the speed of light in vacuum, where λ Lstands for a laser wavelength signal, where Δλ is the difference between the wavelength signal of the stimulated Raman scattered light and the laser wavelength signal in the fiber. Therefore, the wavelength signal of the stimulated Raman scattered light λ SRS in the fiber using the following formula: λSRS=λL+Δλ

[0051] For example, for a laser light with a wavelength signal λ L of 1080 nm the stimulated Raman scattered light signal λ SRS in a quartz fiber about 1132 nm.

[0052] Depending on the difference between the laser wavelength signal λ L and the wavelength signal of the stimulated Raman scattered light λ SRSthe filters 23 located on the photodetector 24 can be provided. In this embodiment, the number of light signal detection devices 2 is set to three. The filter 23 on one of the light signal detection devices 2 can be provided such that it only passes the laser light signal, while another of the filters 23 can be provided such that it only passes the wavelength signal of the stimulated Raman scattered light, so that a current laser wavelength signal λ L1 and a current wavelength signal of the stimulated Raman scattered light λ SRS1It should be noted that the light signal detecting device 2 that detects the current laser light signal and the light signal detecting device that detects the current wavelength signal of the stimulated Raman scattered light may be photodetector 24 with the same wavelength response or photodetector 24 with different wavelength response, and their specific settings and measurement sequences are not limited.

[0053] S40: Calculating a relative intensity depending on the laser wavelength signal I λL and the wavelength signal of the stimulated Raman scattered light I λSRS in the output laser light;

[0054] The relative intensity is represented by ΔI and is generally calculated using the following formula: ΔI=IλLIλ SRS(dB)

[0055] This serves to characterize the extent of the influence of the stimulated Raman scattered light on the fiber laser device 1000. The influence on the stability of the laser system is evaluated by the magnitude of the relative intensity ΔI. In general, a larger value of the relative intensity ΔI indicates that the laser wavelength signal is significantly larger than the wavelength signal of the stimulated Raman scattered light; therefore, the stimulated Raman scattered light has a smaller influence on the stability of the fiber laser device 1000. A smaller value of the relative intensity ΔI indicates that the laser wavelength signal gradually approaches the wavelength signal of the stimulated Raman scattered light; at this time, the stimulated Raman scattered light has a greater influence on the stability of the fiber laser device 1000.If the relative intensity ΔI reaches a certain threshold, measures must be taken to reduce the wavelength of the stimulated Raman scattered light.

[0056] S50: Controlling, depending on a relationship between the relative intensity and a set threshold, the fiber laser generator 1 to regulate a wavelength and an output power of a laser light output by the pump source 11 or to stabilize it in a current operating state.

[0057] In one embodiment of the present application, the set threshold is set to 30 dB. It should be understood that under normal circumstances, in the case of ΔI ≥ 30 dB, the stimulated Raman scattered light signal has little or no influence on the stability of the fiber laser device 1000 and can thus be neglected, and the fiber laser generator is controlled to be stabilized in the current operating state. In the case of ΔI < 30 dB, the stimulated Raman scattered light signal has a greater influence on the stability of the fiber laser device 1000, and it is necessary to control the wavelength and output power of the output laser light of the fiber laser generator 1 to increase the relative intensity ΔI to satisfy the above-mentioned set threshold relationship.

[0058] In one embodiment, the step of “controlling, depending on a relationship between the relative intensity and a set threshold value, the fiber laser generator to regulate a wavelength and an output power of a laser light emitted by the pump source 11 or to stabilize it in a current operating state” comprises: S501: Controlling the fiber laser generator 1 to regulate the wavelength and output power of the laser light output by the pump source 11 when a current relative intensity is below the set threshold.

[0059] According to the embodiment described above, for example, at a threshold value of 30 dB and an actual relative intensity ΔI1 below 30 dB, the stimulated Raman scattered light signal has a greater influence on the stability of the fiber laser device, and the wavelength and output power of the output laser light of the pump source 11 of the fiber laser generator 1 must be controlled to increase the relative intensity.

[0060] In this embodiment, the volume grating 114 is arranged on a side of the collimating lens 113 remote from the pump semiconductor laser chip 111 and can control the laser wavelength of the pump semiconductor laser chip 111. Specifically, the central wavelength selected by the volume grating 114 can be expressed by the following formula: λc=2neffΛ

[0061] Where λ c for the central wavelength selected by the volume grating 114, where n effstands for an effective refractive index of the grating area and ∧ for the grating period. The control system controls the piezoceramic 1141 or temperature control board 1142 arranged on the volume grating 114 and controls the stress and temperature of the volume grating 114 to determine the effective refractive index n eff of the grating region, thereby changing the wavelength of the output laser. Furthermore, the control device 4 regulates the power of the laser output from the pump source 11 via the constant current driver board and subsequently obtains a regulated output laser light.

[0062] S502: Acquiring an output laser light intensity in a controlled output laser light detected by the plurality of light signal detecting devices, and calculating a controlled relative intensity.

[0063] In this embodiment, the number of the light signal detectors 2 is set to three, two of the light signal detectors 2 are used to detect the laser wavelength signal and the wavelength signal of the stimulated Raman scattered light in the controlled output laser light, and the remaining light signal detector 2 is used to detect the laser wavelength before the control to monitor the stability of the power of the output laser light after the automatic control and thus keep the final intensity of the output laser light constant.It should be noted that the filter 23 of the optical signal detector 2 for detecting the laser wavelength before control is configured as a filter 23 that can only transmit the laser wavelength. The three optical signal detectors 2 may have the same wavelength response or different wavelength responses, and the order of mounting the three optical signal detectors 2 is not limited. Furthermore, the controlled relative intensity ΔI2 can be determined based on the laser wavelength signal and the wavelength signal of the stimulated Raman scattered light after control, which are detected by the plurality of optical signal detectors 2.

[0064] S503: Compare the output laser light intensity before control with the output laser light intensity before control and calculate a change value ΔI L the laser light output intensity;

[0065] Since the laser intensity changes before and after the control, the corresponding change value ΔI L of the laser light output intensity by the control system. More precisely, ΔI L the laser intensity after control minus the laser intensity before control and is used to characterize the change in the output laser light intensity before and after control.

[0066] S504: Controlling the fiber laser device 1000 to stabilize at a current wavelength and a current output power of the laser light output by the pump source when the controlled relative intensity is greater than or equal to the set threshold and the change value ΔI L the laser light output intensity is within a preset range;

[0067] If the controlled relative intensity is greater than or equal to the set threshold, the stimulated Raman scattered light signal has little or no influence on the stability of the fiber laser device 1000 and can be neglected. Furthermore, by adjusting the change value ΔI L By adjusting the laser light output intensity to the preset range, the laser intensity after adjustment and the laser intensity before adjustment are kept the same, or the change values ​​of the laser intensity before and after adjustment are limited within a small range to ensure that the output laser light intensity does not undergo large changes while suppressing the stimulated Raman scattering effect. At this time, the fiber laser generator is controlled to be stably stabilized in the current operating state.

[0068] S505: Repeating the above-mentioned step of controlling the fiber laser generator 1 to control a wavelength and an output power of the laser light output by the pump source 11 when the controlled relative intensity is below the set threshold.

[0069] If the controlled relative intensity is greater than or equal to the set threshold, the above-mentioned step of controlling the pump source 11 is repeated to increase the relative intensity after re-control until the above-mentioned requirement is met.

[0070] The preset range is -0.5% ≤ ΔI L ≤ 0.5%. If the change value ΔI Lbetween the output laser light intensity before control and the output laser light intensity after control is in the range of -0.5% to 0.5%, it can ensure that the intensity of the laser output is not changed significantly, which can reduce the influence of the stimulated Raman scattering effect while ensuring that the laser light intensity remains relatively unchanged.

[0071] In a further embodiment, it is provided that the control method after the step “calculating a relative intensity depending on the laser wavelength signal I λL and the wavelength signal of the stimulated Raman scattered light I λSRS in the output laser light” further includes: S401: Acquire a relative measurement intensity of the output laser light measured by the relative laser intensity test device 3.

[0072] The Relative Laser Intensity Testing Device 3 is a spectrum analyzer (OSA), an optical instrument for testing the intensity of a single light signal or the relative intensity of multiple light signals. Thus, it can measure the relative intensities of the laser light and stimulated Raman scattered light.

[0073] S402: Controlling, depending on the relative measurement intensity, a light transmittance of the light signal detection devices 2 in order to correct the relative intensity until a current relative intensity is equal to the relative measurement intensity.

[0074] Since there is a certain difference between the calculated relative intensity and the relative measurement intensity, the intensity of the laser light entering the photodetector 24 is changed by controlling the light transmittance of the light signal detecting device 2 (more precisely, the aperture adjusting device 223 is adjusted) so that the calculated relative intensity after the control is equal to the relative measurement intensity, thus achieving the final correction effect.

[0075] The above are only optional embodiments of the present application and are not intended to limit the scope of the patent of the present application, and any equivalent structural transformations made according to the inventive concept of the present application using the contents of the specification of the present application and the accompanying drawings or directly / indirectly applied in other related technical fields are included in the scope of the patent protection of the present application.

Claims

[1] A control method for a fiber laser device, the fiber laser device comprising an electrically connected fiber laser generator, the fiber laser generator comprising a pump source, a plurality of light signal detection devices, a device for checking relative laser intensity, and a control device, the control method for the fiber laser device comprising the following steps: Acquiring a start command; Controlling, upon receiving the start command, the fiber laser generator to operate so that a laser light is output; Acquiring a laser wavelength signal and a wavelength signal of stimulated Raman scattered light in an output laser light detected by the plurality of light signal detecting devices; Calculating a relative intensity depending on the laser wavelength signal and the wavelength signal of the stimulated Raman scattered light in the output laser light; Controlling, depending on a relationship between the relative intensity and a set threshold, the fiber laser generator to regulate a wavelength and an output power of a laser light emitted by the pump source or to stabilize it in a current operating state. [2] A control method for a fiber laser device according to claim 1, wherein the step of “controlling, depending on a relationship between the relative intensity and a set threshold, the fiber laser generator to regulate a wavelength and an output power of a laser light output by the pump source or to stabilize in a current operating state” comprises: Controlling the fiber laser generator to regulate the wavelength and output power of the laser light emitted by the pump source when a current relative intensity is below the set threshold; Acquiring an output laser light intensity in a controlled output laser light detected by the plurality of light signal detecting devices, and calculating a controlled relative intensity; Comparing the output laser light intensity before control with the output laser light intensity before control and calculating a change value of a laser light output intensity; Controlling the fiber laser device to stabilize at a current wavelength and a current output power of the laser light output by the pump source when the controlled relative intensity is greater than or equal to the set threshold and the change value of the laser light output intensity is within a preset range; Repeating the above step of controlling the fiber laser generator to control a wavelength and an output power of the laser light output by the pump source when the controlled relative intensity is below the set threshold. [3] A control method for a fiber laser device according to claim 2, wherein the preset range is between -0.5% and 0.5%. [4] A control method for a fiber laser device according to claim 1, further comprising, after the step of calculating a relative intensity depending on the laser wavelength signal and the wavelength signal of the stimulated Raman scattered light in the output laser light: Acquiring a relative measurement intensity of the output laser light measured by the relative laser intensity testing device; Controlling, depending on the relative measurement intensity, a light transmittance of the light signal detection devices in order to correct the relative intensity until a current relative intensity is equal to the relative measurement intensity. [5] Fiber laser device, the fiber laser device comprising: a fiber laser generator for outputting a laser light; a plurality of light signal detecting devices disposed within the fiber laser generator and used to detect a laser wavelength signal, a wavelength signal of stimulated Raman scattered light, and a value of an output laser light intensity in one of the fiber laser generator; a relative laser intensity test device used to measure a relative measurement intensity of the output laser light of the fiber laser generator; and a control device electrically connected to the fiber laser generator, the plurality of light signal detection devices, and the relative laser intensity testing device, the control device comprising a memory, a processor, and a fiber laser device control program stored on the memory and executable on the processor, the fiber laser device control program being configured to implement the steps of the fiber laser device control method according to any one of claims 1 to 4. [6] A fiber laser device according to claim 5, wherein each of the light signal detecting means comprises: an optical power transmission fiber for providing a signal of the output laser light; a hollow body, wherein an interior of the hollow body is spherically shaped, wherein an outer surface of the hollow body is provided with a through hole and a light-transmitting hole which are arranged at a distance from each other, wherein the through hole is provided for the passage of the optical energy transmission fiber, wherein an aperture adjusting device is provided at the light-transmitting hole; a filter arranged at the light-transmitting hole; and a photodetector arranged on the filter and used to detect a laser light signal emerging from the light-transmitting hole and passing through the filter, and to convert the laser light signal into an electrical signal and transmit it to the control device. [7] The fiber laser device according to claim 5, wherein the relative laser intensity checking means is a spectrum analyzer used to measure a relative measurement intensity of the output laser light. [8] A fiber laser device according to claim 5, wherein the fiber laser generator comprises: two pump sources comprising a forward pump source and a reverse pump source, and used to provide a laser light source; two pump light couplers, each comprising a double-clad fiber, wherein an inner cladding of the two double-clad fibers is coupled to the forward pump source and the reverse pump source, respectively; a fiber laser resonator, each end of which is connected to a fiber of the respective pump light coupler; two cladding light strippers comprising a first stripper and a second stripper, one end of the first stripper being connected to the fiber of the reverse pump source and the other end of the first stripper being connected to the second stripper, the light signal detection means performing spatial optical signal detection between the first stripper and the second stripper; and a laser output head connected to the second stripper and used to connect to a laser processing head and output a laser light. [9] A fiber laser device according to claim 8, wherein each of the pump sources comprises: a pump semiconductor laser chip for converting electrical energy into a divergent laser output; a heat sink device for dissipating heat from the pump semiconductor laser chip; a collimating lens arranged on one side of the pump semiconductor laser chip and used to collimate a divergent laser light output by the pump semiconductor laser chip into parallel light; a volume grating arranged on a side of the collimating lens remote from the pump semiconductor laser chip and used to control a laser wavelength of the pump semiconductor laser chip; a focusing lens arranged on a side of the volume grating remote from the pump semiconductor laser chip and used to focus the laser light output from the pump semiconductor laser chip; a fiber end cap arranged on a side of the focusing lens remote from the pump semiconductor laser chip, wherein a focus of a focused beam converges at the fiber end cap; and a pump light output fiber arranged on a side of the fiber end cap remote from the pump semiconductor laser chip and used to output a pump laser light. [10] Fiber laser device according to claim 9, wherein a piezoceramic or a temperature control plate is arranged on the volume grating.

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