CN219937584U - Small-volume high-power fiber laser and laser processing equipment - Google Patents

Abstract

The utility model discloses a small-volume high-power fiber laser and laser processing equipment, wherein the laser comprises a first pumping source, a forward beam combiner, a resonant cavity, a reverse beam combiner and a second pumping source which are sequentially connected, the resonant cavity comprises a broadband high-reflection grating, an active optical fiber and a broadband low-reflection grating which are sequentially connected, pump light generated by the first pumping source and the second pumping source is respectively input into the resonant cavity through the forward beam combiner and the reverse beam combiner, the laser adopts the pumping source with the wavelength of 900nm-999nm, the working bandwidth of the broadband high-reflection grating is 4nm-8nm, the working bandwidth of the broadband low-reflection grating is 2nm-4nm, the intensity of light with different wavelengths in the working bandwidth is reduced, the Raman effect of the laser is reduced, and the fiber laser can realize laser output with high power and good beam quality on the premise of miniaturization and cost saving.

Description

Small-volume high-power fiber laser and laser processing equipment

Technical Field

The utility model belongs to the technical field of laser processing, and particularly relates to a small-volume high-power fiber laser and laser processing equipment.

Background

Since the development of the last sixties of century, fiber lasers have been increasingly used in medical health, processing and manufacturing, defense and military and other fields with the performance advantages of strong electromagnetic interference resistance, small volume, high light-light conversion efficiency, convenient heat dissipation, compact structure and the like. Meanwhile, compared with other types of lasers, the fiber laser can realize laser output with the magnitude of kW or more and simultaneously maintain good beam quality.

Compared with multimode kW magnitude fiber lasers, single-mode and quasi-single-mode fiber lasers are more suitable for the industries of laser welding, laser marking and the like due to good beam quality characteristics. At first, the method is limited by factors such as single-mode gain fiber pump coupling efficiency, nonlinear effect and the like, domestic and foreign research teams can not realize kW-level laser output of a fiber laser while maintaining good beam quality, and because the heat collection phenomenon exists at the fiber during high-power output of the laser, TMI effect and Raman effect are easy to generate, and the power improvement of the laser is limited. Until 2006, the IPG company uses the same-band pumping technology to realize laser output with the wavelength of 1075nm, the highest laser power of 1960W and the beam quality of 1.2 in the fiber laser with the fiber core diameter of 15 μm, and uses the same-band pumping technology to realize laser output with the wavelength of 20kW in 2013, so that a feasible scheme is provided for the fiber laser to realize high-power output and maintain good beam quality.

In the same band pumping technical scheme, compared with a 9XX (the pumping wavelength is in the range of 900nm-999 nm) series pumping source, the pumping source wavelength is closer to the oscillation wavelength, the light-light conversion efficiency is higher, the thermal management is more convenient, and the mode instability threshold is higher. However, the gain fiber in the technology often needs several tens of meters in service length, so that the whole fiber laser is large in size, the miniaturization of the laser is not facilitated, and meanwhile, the cost of a device of the scheme is high, and the cost is not facilitated to be saved. The use length of the gain optical fiber matched with the 9XX series pump source is usually less than 22m, so that the whole optical fiber laser is smaller in size, meanwhile, the 9XX series pump source is more mature to prepare, the preparation cost is lower, and the production cost is saved. Therefore, in response to the overall performance requirements of the laser welding industry for single mode fiber lasers, there is an urgent need to develop a miniaturized fiber laser that has both kW-scale and good beam quality laser output.

Disclosure of Invention

The embodiment of the utility model aims to provide a small-size high-power fiber laser and laser processing equipment, so that the fiber laser can realize laser output of high-power and good-beam quality laser on the premise of miniaturization and cost saving.

The utility model solves the technical problems by adopting the following technical scheme:

the small-volume high-power fiber laser comprises a first pump source, a forward beam combiner, a resonant cavity, a reverse beam combiner and a second pump source which are sequentially connected, wherein the resonant cavity comprises a broadband high-reflection grating, an active fiber and a broadband low-reflection grating which are sequentially connected, and pump light generated by the first pump source and the pump light generated by the first pump source are respectively input into the resonant cavity through the forward beam combiner and the reverse beam combiner; wherein the wavelength of the pumping light generated by the pumping source is 900nm-999nm.

Preferably, the active optical fiber has a core diameter of 12 μm to 16 μm and a cladding diameter of 240 μm to 260 μm.

As a preferable scheme, the working bandwidth of the broadband high-reflection grating is 4nm-8nm, the working bandwidth of the broadband low-reflection grating is 2nm-4nm, the central working wavelength of the broadband high-reflection grating is 1080nm, the reflectivity of the broadband high-reflection grating to the wavelength light in the working bandwidth is more than or equal to 99%, the central working wavelength of the broadband low-reflection grating is 1080nm, and the reflectivity of the broadband low-reflection grating to the wavelength light in the working bandwidth is 9% -11%.

Preferably, the ratio of the power of the total pump Pu Guang connected to the forward beam combiner to the power of the total pump Pu Guang connected to the backward beam combiner is between 1:1.5 and 1:3.

As a preferred scheme, the fiber laser further comprises a reverse mode stripper, the reverse mode stripper is connected with the forward beam combiner through the passive fiber, and the passive fiber between the reverse mode stripper and the forward beam combiner forms a reverse stripping winding small ring through winding, so as to eliminate the laser transmitted in the fiber core in the reverse direction.

Preferably, the bending radius of the small winding circle of the optical fiber is 2.5cm-3.5cm, and the winding circle number is 4-6.

Preferably, the wavelength of the pump light is 915nm or 976nm.

Preferably, the output power of the fiber laser is 1kW-4kW.

As a preferable scheme, the fiber laser further comprises a water cooling plate, and the first pumping source, the second pumping source, the forward beam combiner, the resonant cavity and the backward beam combiner are respectively arranged on two sides of the water cooling plate.

The utility model also provides laser processing equipment, which comprises the optical fiber laser of any scheme.

The beneficial effects of the utility model are as follows: by adopting a double-end pumping mode, continuous laser with a small-core fiber output kW level and above is realized, and a mode instability (TMI) threshold is improved; the high absorption capacity of the gain fiber to the pumping light with the wavelength of 9XX series (the pumping light wavelength is 900nm-999 nm) is utilized, so that the length of the gain fiber is greatly shortened, and the volume of the fiber laser can be reduced; meanwhile, the resonator adopts the broadband high-reflection grating and the broadband low-reflection grating, so that the working bandwidth of the resonator is enlarged, and the laser reduces the intensity of lasers (or signal lights) with different wavelengths in the working bandwidth on the premise of outputting the same power, thereby effectively reducing the heat collection degree in the gain fiber, improving the Raman threshold and effectively improving the beam quality of the output laser.

Drawings

One or more embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements, and in which the figures of the drawings are not to scale, unless expressly stated otherwise.

FIG. 1 is a schematic diagram of a broadband grating-based small-volume high-power fiber laser;

FIG. 2 is a schematic diagram of a specific optical path of a broadband grating-based small-volume high-power fiber laser;

FIG. 3 is a front view of a broadband grating based small-volume high-power fiber laser;

fig. 4 is a back structure diagram of a small-volume high-power fiber laser based on broadband grating.

Detailed Description

In order that the utility model may be readily understood, a more particular description thereof will be rendered by reference to specific embodiments that are illustrated in the appended drawings. It will be understood that when an element is referred to as being "fixed" to "/" affixed "to" another element, it can be directly on the other element or one or more intervening elements may be present therebetween. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or one or more intervening elements may be present therebetween. The terms "vertical," "horizontal," "left," "right," "inner," "outer," and the like are used in this specification for purposes of illustration only.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this novel technology belongs. The terminology used in the description of the utility model herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the utility model. The term "and/or" as used in this specification includes any and all combinations of one or more of the associated listed items.

In addition, the technical features mentioned in the different embodiments of the utility model described below can be combined with one another as long as they do not conflict with one another.

The up-down orientation of the various components of the device is now defined when the device is in the state shown in fig. 3.

Referring to fig. 1 and 2, fig. 1 is a schematic diagram of a small-volume high-power fiber laser based on a broadband grating, and fig. 2 is a specific light path diagram of a small-volume high-power fiber laser based on a broadband grating.

Specifically, the small-volume high-power fiber laser disclosed in the present embodiment includes a first pump source 1, a passive fiber 11, a forward combiner 3, and a resonant cavity 5. The resonant cavity 5 includes a broadband high reflection grating 51, an active optical fiber 53 and a broadband low reflection grating 52, which are sequentially connected. One end of the forward beam combiner 3 is connected with the broadband high reflection grating 51 through the passive optical fiber 11, and the first pump source 1 is connected with the other end of the forward beam combiner 3 through the passive optical fiber 11.

The laser of this embodiment further includes a reverse beam combiner 4, and a second pump source 2, where one end of the reverse beam combiner 4 is connected to the broadband low reflection grating 52 through a passive optical fiber 11, and the second pump source 2 is connected to the other end of the reverse beam combiner 4 through the passive optical fiber 11.

The laser further comprises an indication light source 6, a reverse mode stripper 7, a reverse wound small turn 9, a passive fiber 11 with a core/cladding diameter of 14/250 μm and a passive fiber 12 with a core/cladding diameter of 20/250 μm.

Wherein, reverse mode stripper 7 one end is connected with instruction light source 6 through passive optic fibre 11, and first pumping source 1 passes through passive optic fibre 12 to be connected at the other end of reverse mode stripper 7 to, passive optic fibre 12 between reverse mode stripper 7 and the forward beam combiner 3 is formed with reverse stripping winding ringlet 9 through the winding, is convenient for increase the higher order mode optical loss through passive optic fibre 12, even is convenient for eliminate high order mode light. Specifically, the reverse mode stripper 7 is used to eliminate the reverse-transmitted laser light leaking from the broadband high-reflection grating 51 into the passive optical fiber 11 and the impurity light in the cladding, so as to avoid damage to the indication light source 6 and other sensing devices.

The optical fiber laser also comprises a forward mode stripper 8, a laser output head 10 and a pumping optical fiber 13 with the fiber core/cladding diameter of 135/155 mu m, wherein one end of the forward mode stripper 8 is connected with the reverse beam combiner 4 through a passive optical fiber 11, and the laser output head 10 is connected with the other end of the forward mode stripper 8 through the passive optical fiber 11.

As shown in fig. 3 and 4, the fiber laser further includes a fiber groove 14, a water cooling plate 15, a water outlet 16, a water inlet 17, and an output pigtail holder 18. Wherein, the resonant cavity 5 and the inverse beam combiner 4 are both arranged on the front surface of the water cooling plate 15, and the first pump source 1 and the second pump source 2 are arranged on the back surface of the water cooling plate 15. Wherein the reversely-stripped winding small ring 9 is horizontally arranged and fixed on the back surface of the water cooling plate 15 by tinfoil.

Specifically, the first pump source 1 is coupled into the passive optical fiber 11 through the pump light generated by the forward combiner 3 and then is input into the resonant cavity 5. The pump light generated by the second pump source 2 is coupled into the passive optical fiber 11 through the inverse beam combiner 4 and then is input into the resonant cavity 5. Then, the pump light inputted into the resonant cavity 5 is amplified in gain to form laser, and outputted from the broadband low reflection grating 52 side, and transmitted to the laser collimation output head 10 through the passive optical fiber 11 to output laser.

Because the two-way pumping mode is adopted, the resonant cavity 5 adopts the broadband high-reflection grating 51 and the broadband low-reflection grating 52, and the broadband high-reflection grating 51 and the broadband low-reflection grating 52 have larger working bandwidths, compared with the traditional high-reflection grating and the traditional low-reflection grating adopted by the resonant cavity of the traditional fiber laser, the working bandwidths are enlarged, so that the laser intensity of each wavelength with the pumping light wavelength of 9XX series (the pumping light wavelength is in the range of 900nm-999 nm) is reduced in the working bandwidths of the fiber gratings on the premise of outputting the same power, the heat collection degree in the gain fiber is reduced, and meanwhile, the Raman threshold and The Mode Instability (TMI) threshold are respectively improved by outputting with small core diameters. The continuous laser of the kW level is output by the small-core fiber on the premise of not utilizing the same-band pumping technology.

Specifically, the center working wavelength of the broadband high reflection grating 51 is 1080nm, the working bandwidth is 4nm-8nm, and the reflectivity of the broadband high reflection grating on the wavelength light in the working bandwidth is more than or equal to 99%. Further, it can be known that the bandwidth of the broadband high reflection grating 51 may be 4nm; the bandwidth of the broadband high reflection grating 51 can be 8nm; the bandwidth of the broadband high reflective grating 51 may be 6nm, which is not illustrated here.

Specifically, the center working wavelength of the broadband low reflection grating 52 is 1080nm, the working bandwidth is 2nm-4nm, and the reflectivity of the broadband low reflection grating to the wavelength light in the working bandwidth is 10% ± 1%. Further, it can be seen that the bandwidth of the broadband low reflection grating 52 may be 2nm; the bandwidth of the broadband high reflective grating 52 may also be 4nm; the broadband high reflective grating 52 may have a bandwidth of 3nm, which is not illustrated herein.

Compared with the prior fiber laser, the broadband high-reflection grating 51 and the broadband low-reflection grating 52 have larger working bandwidths on the premise of outputting the same power, so that the intensities of the pumping light with different wavelengths, which adopts the pumping light wavelength of 9XX series (the pumping light wavelength is in the range of 900nm-999 nm), are greatly reduced, the heat collection degree in the gain fiber is reduced, and meanwhile, the Raman threshold and The Mode Instability (TMI) threshold are respectively improved by small-core output. So that a small core transmission fiber can carry more laser power.

In one embodiment, the first pump source 1 and the second pump source 2 generate pump light having a uniform wavelength, for example, 915nm at the same time or 976nm at the same time.

In one embodiment, the core diameter of the active optical fiber 53 is 12 μm-16 μm, the core diameter of the passive optical fiber 11 is 12 μm-16 μm, and the core diameter of the passive optical fiber 12 is 18 μm-22 μm, so that continuous laser can be output in a small-core optical fiber with a kW level on the premise of not using the same-band pumping technology, and the output power of the fiber laser can reach 1kW-4kW, or even higher.

Further, it can be known that the core diameter of the active optical fiber 53 may be 12 μm; the core diameter of the active optical fiber 53 may also be 16 μm; the core diameter of the active optical fiber 53 may be 13 μm, which is not shown here.

In one embodiment, the ratio of the total pump light power accessed by the forward combiner 3 to the total pump Pu Guang power accessed by the backward combiner 4 is between 1:1.5-1:3. The Raman threshold of the fiber laser is improved as much as possible, so that the influence of the Raman effect on the fiber laser is reduced as much as possible.

Of course, in other embodiments, the ratio of the total pump power accessed by the forward beam combiner 3 to the total pump power accessed by the backward beam combiner 4 is 1:1.5. The ratio of the total pump light power accessed by the forward beam combiner 3 to the total pump light power accessed by the backward beam combiner 4 is 1:3. The ratio of the total pump light power accessed by the forward beam combiner 3 to the total pump light power accessed by the backward beam combiner 4 is 1:1.8, which is not shown here.

In one embodiment, the bending radius of the reversely-stripped winding small circle 9 is 2.5cm-3.5cm, the winding circle number is 4-6, the high-order mode transmission loss of the fiber core of the passive optical fiber 11 is increased, the winding circle number is enough to ensure that the high-order mode light can be transmitted to be gradually attenuated to be 0 in the small circle, an optical device for filtering the high-order mode is not required to be additionally added, the operation is simple and convenient, the cost is saved, the reverse transmission laser in the fiber core is eliminated, the transmission loss of a single mode in the fiber core is not influenced, and the laser can keep good beam transmission quality as much as possible.

In addition, cold water can be transmitted inside the water cooling plate 15 for heat dissipation. An active optical fiber 53 is installed in the optical fiber groove 14 and is used as an excitation medium for exciting the pump light. Based on the existing laser, the radius of the inner ring of the optical fiber groove is 12cm, and the radius of the outer ring is 22cm, so that the heat dissipation of the active optical fiber 53 is facilitated. The output pigtail holder 18 is used for holding the pigtail and serves as a holder to prevent the fiber and other optical devices from being damaged by drag.

Of course, in other embodiments, the radius of the inner and outer rings of the optical fiber groove 14 is above 8cm, and the upper limit is determined by the size of the specific laser housing, so that the phenomenon that the active optical fiber 53 placed in the optical fiber groove 14 is burnt seriously due to too small inner diameter is avoided, and meanwhile, the situation that other devices on the water cooling plate 15 are not assembled well due to too large inner diameter is avoided.

The utility model also provides laser processing equipment, which comprises the optical fiber laser of any scheme.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present utility model, and are not limiting; the technical features of the above embodiments or in the different embodiments may also be combined within the idea of the utility model, the steps may be implemented in any order, and there are many other variations of the different aspects of the utility model as described above, which are not provided in detail for the sake of brevity; although the utility model has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the utility model.

Claims (10)

1. The small-volume high-power fiber laser is characterized by comprising a first pump source, a forward beam combiner, a resonant cavity, a reverse beam combiner and a second pump source which are sequentially connected, wherein the resonant cavity comprises a broadband high-reflection grating, an active fiber and a broadband low-reflection grating which are sequentially connected, and pump light generated by the first pump source and the second pump source is input into the resonant cavity through the forward beam combiner and the reverse beam combiner respectively; wherein the wavelength of the pumping light generated by the pumping source is 900nm-999nm.

2. The fiber laser of claim 1, wherein the active fiber has a core diameter of 12 μm to 16 μm and a cladding diameter of 240 μm to 260 μm.

3. The fiber laser of claim 1, wherein the broadband high-reflection grating has an operating bandwidth of 4nm-8nm, the broadband low-reflection grating has an operating bandwidth of 2nm-4nm, the broadband high-reflection grating has a center operating wavelength of 1080nm, the reflectivity of the broadband high-reflection grating for wavelength light within the operating bandwidth is greater than or equal to 99%, the broadband low-reflection grating has a center operating wavelength of 1080nm, and the reflectivity of the broadband low-reflection grating for wavelength light within the operating bandwidth is 9% -11%.

4. The fiber laser of claim 1, wherein the ratio of the total pump Pu Guang power accessed by the forward combiner to the total pump Pu Guang power accessed by the reverse combiner is between 1:1.5-1:3.

5. The fiber laser of claim 1, further comprising a reverse stripper connected to the forward combiner by a passive fiber, the passive fiber between the reverse stripper and the forward combiner being wound to form a reverse stripper winding loop for eliminating reverse transmitted laser light in the fiber core.

6. The fiber laser of claim 5, wherein the bend radius of the counter-stripping winding turns is 2.5cm-3.5cm and the number of turns is 4-6.

7. The fiber laser of claim 1, wherein the pump light has a wavelength of 915nm or 976nm.

8. The fiber laser of claim 1, wherein the fiber laser has an output power of 1kW-4kW.

9. The fiber laser of claim 1, further comprising a water cooled plate, wherein the first pump source, the second pump source, the forward combiner, the resonant cavity, and the backward combiner are disposed on two sides of the water cooled plate, respectively.

10. A laser processing apparatus comprising a fibre laser as claimed in any one of claims 1 to 9.