A multi-core doped rare earth ion multi-wavelength power adjustable fiber laser

Abstract

The application discloses a multi-core doped rare earth ion multi-wavelength power adjustable optical fiber laser. The multi-core doped rare earth ion multi-wavelength power adjustable optical fiber laser can realize high-power composite wavelength fiber laser output with the output power of multiple wavelengths being controlled individually. The composite wavelength fiber laser uses a multi-core doped active optical fiber as a gain fiber, and combines a signal light+pump light combiner to realize the amplification output of the signal light.

Description

Technical Field

[0001] The present invention relates to a multi-core rare earth ion doped multi-wavelength power tunable optical fiber laser, which can be used to realize high-power amplified output of the multi-wavelength optical fiber laser. Background Art

[0002] Fiber lasers have been widely applied in numerous research fields, such as industry, medicine, and scientific research. In particular, with the continuous advancement of technologies in these research fields, new demands for laser technology applications are constantly emerging to meet these evolving needs, driving the rapid development of related research fields and ultimately, promoting rapid progress in society. In recent years, as fiber laser technology and its manufacturing processes have gradually matured, fiber lasers in various types, including continuous, quasi-continuous, pulsed, multi-wavelength or single-wavelength, and polarization-maintaining or non-polarization-maintaining, have become mature products and are being applied in various industries. With the development of various industries, each is gradually moving towards high-end, sophisticated manufacturing to enhance the technical capabilities of creating high-end products. In recent years, the fields of medicine, precision materials processing, and scientific research have also seen rapid development. In particular, composite wavelength laser technology, based on the superposition of multiple wavelengths, has been applied in these fields. Examples include multi-wavelength test light sources, dental care, and metal surface treatment.

[0003] Currently, the main technologies used for multi-wavelength lasers include laser frequency doubling, resonant cavity multi-wave oscillation, ASE combined with grating arrays, and quantum dot semiconductor lasers. Each of these technologies has its own unique advantages and drawbacks in achieving multi-wavelength lasers. For example, 1. Optical frequency doubling: Laser frequency doubling significantly expands the wavelength range of lasers and is the primary method for converting lasers to shorter wavelengths. This method primarily utilizes a pump laser combined with a nonlinear crystal to achieve multi-wavelength laser output. However, this method has certain limitations: ① The low conversion efficiency of nonlinear crystals limits high-power output; ② Due to their spatial structure, their stability and reliability are relatively poor compared to all-fiber lasers. ③ To achieve multiple wavelengths of laser output, multiple frequency doubling cycles are often required, which can lead to a more complex spatial structure. ④ In terms of application, it is difficult to individually control multiple wavelengths, resulting in limited application flexibility. 2. Resonant cavity: This method primarily utilizes a multi-wavelength grating pair or a multi-wavelength coated cavity mirror in conjunction with a gain medium to form a multi-wavelength resonant cavity to achieve multi-wavelength laser output. The output power of each wavelength of the multi-wavelength laser obtained using this method is uncontrollable, primarily determined by the resonant cavity losses and the gain curve of the gain medium. Furthermore, the output power corresponding to each wavelength cannot be individually controlled, resulting in a lack of flexibility in application. 3. Combining amplified spontaneous emission (ASE) with a multi-wavelength grating array: This method utilizes the spontaneous emission effect of the gain medium to generate a broad spectrum. The multi-wavelength grating array then separates the multiple discrete wavelengths. These multiple discrete wavelength lasers are then combined to form a multi-wavelength composite laser. However, the spontaneous emission process is generally accompanied by reabsorption, resulting in poor output efficiency and easily causing heating of the gain medium. Therefore, this method has serious drawbacks in achieving high-power output. Furthermore, the output power of individual wavelength lasers cannot be individually controlled. 4. Quantum cascade laser: This method primarily utilizes quantum semiconductor materials to produce multi-wavelength lasers. This method can produce lasers with a wide wavelength range, covering the mid-infrared and far-infrared. Due to its inherent physical properties, the maximum output power of a single module is generally limited to watts, and its price is relatively high. Therefore, it is generally used in scientific research. In addition, it is impossible to individually control the output power of a single wavelength laser.

[0004] Existing fiber output using multi-core technology, such as CN101719621A, utilizes discrete doped cores to achieve multi-wavelength output. This not only complicates fiber fabrication but also reduces space utilization, making high-power processing difficult. CN109286122A employs fan-shaped partitioning to create multiple doped regions. These regions are susceptible to mutual interference, and the output laser is difficult to apply in high-power laser processing scenarios. Although CN101814687A and others mention multi-layered annular doped amplifying fibers, this is merely a simple concept for gain fibers and does not address the issues of how to rationally design pump and signal input and coupling structures to reduce coupling losses and laser dissipation. Furthermore, the ingenious design of an all-fiber structure without increasing the laser and energy loss rate is particularly important in high-power processing scenarios. Every 1% reduction in energy loss in a laser processing device can save tens of thousands of dollars in electricity costs. In the field of high-power laser processing, much creative work is needed to optimize energy utilization and maximize energy efficiency.

[0005] To address the two key technical issues common to all of the aforementioned multi-wavelength laser generation technologies and limiting their application, namely, the difficulty in achieving high-power output and the uncontrollable output of single-wavelength lasers, and the lack of a simple and stable overall laser coupling and pumping structure that can simultaneously improve energy utilization and reduce nonlinear effects, the solution described in this patent uses a multi-core rare-earth ion-doped fiber as a gain fiber to achieve controllable high-power multi-wavelength fiber laser output. Summary of the Invention

[0006] The purpose of the present invention is to provide a multi-doped rare earth ion multi-wavelength fiber laser.

[0007] To solve the above problems, the present invention creatively transforms the structure of the multi-layer fiber core, cleverly combines the designed fiber bundle structure with the unique multi-core doped fiber, and provides a laser that outputs a composite wavelength annular spot laser.

[0008] The invention discloses a multi-doped rare earth ion multi-wavelength fiber laser, which can realize high-power composite wavelength fiber laser output with independently controllable output powers of multiple wavelengths.

[0009] The composite wavelength fiber laser uses a multi-core doped active fiber as a gain fiber and combines the signal light + pump light combiner to achieve amplified output of the signal light.

[0010] The composite wavelength fiber laser mainly consists of four parts: signal light and pump light module, signal light and pump light output fiber bundling area, bundling tapered area, and multi-core doped active fiber.

[0011] The signal light and pump light module includes a signal light module and a pump light module. The signal light module can output the signal laser to be amplified. Preferably, the signal light module can simultaneously output the signal laser to be amplified including two wavelengths, namely, the first signal laser L1 and the second signal laser L2. The first signal laser or L1 and the second signal laser L2 can be output from the signal light module through their respective waveguide output structures or spatial light output structures; preferably, the signal light module can simultaneously output three wavelengths of signal laser to be amplified, namely, the first signal laser L1, the second signal laser L2, and the third signal laser L3. The first signal laser or L1, the second signal laser L2, and the third signal laser L3 can be output from the signal light module through their respective waveguide output structures or spatial light output structures; preferably, the signal light module can simultaneously output n wavelengths (n>3, a positive integer) of signal laser to be amplified, namely, the first signal laser L1, the second signal laser L2, the third signal laser L3, (the fourth signal laser L4) ... the nth signal laser Ln. The first signal laser L1 , the second signal laser L2 , the third signal laser L3 , (the fourth signal laser L4 ) . . . the nth signal laser Ln can be output from the signal light module through their respective waveguide output structures or spatial light output structures.

[0012] The pump light module outputs the corresponding pump light required to achieve signal light amplification. Preferably, the pump light includes pump lasers of multiple wavelengths corresponding to the multiple wavelengths of signal light. Preferably, when the signal light module can simultaneously output two wavelengths of signal lasers to be amplified, namely the first signal laser L1 and the second signal laser L2, the pump light module outputs two wavelengths of corresponding pump light, namely the first pump laser P1 and the second pump laser P2; preferably, the signal light module can simultaneously output three wavelengths of signal lasers to be amplified, namely the first signal laser L1, the second signal laser L2, and the third signal laser L3. When the laser L3 is used, the pump light module outputs corresponding pump lights of three wavelengths, namely the first pump laser P1, the second pump laser P2, and the third pump laser P3; preferably, the signal light module can simultaneously output n wavelengths (n>3, a positive integer) of signal lasers to be amplified, namely the first signal laser L1, the second signal laser L2, the third signal laser L3, (the fourth signal laser L4)...When the nth signal laser Ln is used, the pump light module outputs corresponding pump lights of n wavelengths, namely the first pump laser P1, the second pump laser P2, the third pump laser P3...the nth pump laser Pn.

[0013] The signal laser corresponds to the laser that can be emitted and / or amplified by the multi-core optical fiber doped with rare earth ion materials, while the pump laser is a pump laser that can be absorbed by the rare earth ions and cause the ion population to flip. Preferably, the first signal laser L1 corresponds to the first pump laser P1, the first rare earth ion material absorbs the first pump laser P1 and flips the ion population, and emits the amplified first signal laser L1; preferably, the second signal laser L2 corresponds to the second pump laser P2, the second rare earth ion material absorbs the second pump laser P2 and flips the ion population, and emits the amplified second signal laser L2; preferably, the third signal laser L3 corresponds to the third pump laser P3, the third rare earth ion material absorbs the third pump laser P3 and flips the ion population, and emits the amplified third signal laser L3; preferably, the nth signal laser Ln corresponds to the nth pump laser Pn, the nth rare earth ion material absorbs the nth pump laser Pn and flips the ion population, and emits the amplified nth signal laser Ln (n>3, a positive integer).

[0014] Preferably, the power of the first pump laser, the second pump laser, the third pump laser...the nth pump laser is independently adjustable, that is, the power of the first pump laser is independently adjustable, that is, the power of the second pump laser is independently adjustable, that is, the power of the third pump laser is independently adjustable, that is, the power of the nth pump laser is independently adjustable (n>3, a positive integer), so as to achieve independent controllability of the output light of each wavelength.

[0015] Preferably, the power of the first signal laser, the second signal laser, the third signal laser ... the nth signal laser is independently adjustable.

[0016] Preferably, the signal laser may be a single-mode signal laser to improve the beam quality of the output light.

[0017] Preferably, the pump laser may be a multi-mode pump laser.

[0018] The signal light and pump light output fiber bundling area includes a signal fiber and a pump fiber, which bundles the signal fiber and the pump fiber. Preferably, it also includes a tube for enclosing the signal fiber and the pump fiber. The tube for enclosing the signal fiber and the pump fiber is a quartz glass tube.

[0019] For convenience, the signal light and pump light output fiber bundling area is referred to as the bundling area below.

[0020] Preferably, the refractive index of the quartz glass tube is also lower than the core refractive index of the signal optical fiber (here, lower than the core refractive index of the signal optical fiber means lower than the core refractive index of all signal optical fibers).

[0021] Preferably, the quartz low-refractive-index glass tube can be manufactured by doping. Preferably, the quartz low-refractive-index glass tube is a fluorine- or boron-doped quartz low-refractive-index glass tube.

[0022] Preferably, the signal optical fiber may be a single-mode optical fiber to obtain good single-mode signal light. Preferably, the signal optical fiber is a 10 / 125 single-mode optical fiber.

[0023] Preferably, the pump fiber adopts a multimode pump fiber that can accommodate high-power multimode light. Preferably, the pump fiber has parameters of 105 / 125 / 0.22.

[0024] Preferably, the cluster area is divided into multiple area parts, preferably, it can include the first part of the cluster area, the second part of the cluster area; preferably, it can include the first part of the cluster area, the second part of the cluster area, the third part of the cluster area; preferably, it can include the first part of the cluster area, the second part of the cluster area, the third part of the cluster area,... the nth part of the cluster area.

[0025] Preferably, each part includes a signal optical fiber and a pump optical fiber.

[0026] Preferably, the signal optical fiber is a passive matching optical fiber capable of transmitting corresponding laser light excited by corresponding ions doped therein.

[0027] Preferably, the pump fiber is a pump source coupling output fiber in the pump optical module.

[0028] Preferably, the various parts of the cluster area are arranged layer by layer starting from the center outwards.

[0029] Preferably, the cluster area has, from the inside to the outside, a first cluster area part, a second cluster area part, a third cluster area part, ... an nth cluster area area (n>3, a positive integer).

[0030] Preferably, the first part of the cluster area is a circular area in the center, the second part of the cluster area is a circular area surrounding the first part of the cluster area, the third part of the cluster area is a circular area surrounding the second part of the cluster area,... the nth part of the cluster area (n>3, a positive integer) is a circular area surrounding the (n-1)th part of the cluster area.

[0031] Each portion of the cluster region preferably includes a respective signal fiber and its corresponding pump fiber.

[0032] Preferably, the first part of the clustering region includes a first signal fiber and a first pump fiber corresponding thereto, the first signal fiber is used to transmit the first signal laser L1, and the first pump fiber is used to transmit the first pump laser P1, preferably there are one or more first signal fibers, preferably there are two or more first signal fibers, preferably there are one or more first pump fibers, preferably there are two or more first pump fibers; preferably, the second part of the clustering region includes a second signal fiber and a second pump fiber corresponding thereto, the second signal fiber is used to transmit the second signal laser L2, and the second pump fiber is used to transmit the second pump laser P2, preferably there are one or more second signal fibers, preferably there are two or more second signal fibers, preferably there are one or more second pump fibers, preferably there are two or more second pump fibers; Preferably, the third part of the clustering area includes a third signal fiber and a corresponding third pump fiber, the third signal fiber is used to transmit the third signal laser L3, and the third pump fiber is used to transmit the third pump laser P3. Preferably, there are one or more third signal fibers, and preferably, there are two or more third signal fibers. Preferably, there are one or more third pump fibers, and preferably, there are two or more third pump fibers. Preferably, the nth part of the clustering area includes an nth signal fiber and a corresponding nth pump fiber, the nth signal fiber is used to transmit the nth signal laser Ln, and the nth pump fiber is used to transmit the nth pump laser Pn. Preferably, there are one or more nth signal fibers, and preferably, there are two or more nth signal fibers. Preferably, there are one or more nth pump fibers, and preferably, there are two or more nth pump fibers.

[0033] Preferably, the first rare earth ion material corresponding to the first signal laser L1 and the first pump laser P1 can be selected from one of rare earth doped materials such as ytterbium-doped material, erbium-doped material, thulium-doped material, neodymium-doped material, holmium-doped material, samarium-doped material, praseodymium-doped material, and erbium-ytterbium co-doped material.

[0034] Preferably, the second rare earth ion material corresponding to the second signal laser L2 and the second pump laser P2 can be selected from one of rare earth-doped materials such as ytterbium-doped materials, erbium-doped materials, thulium-doped materials, neodymium-doped materials, holmium-doped materials, samarium-doped materials, praseodymium-doped materials, and erbium-ytterbium co-doped materials. Preferably, the second rare earth ion material should be different from the first rare earth ion material and can be used to emit different, controllable, annular layered wavelengths. That is, the wavelength of the second signal laser L2 is different from the wavelength of the first signal laser L1.

[0035] Preferably, the third rare earth ion material corresponding to the third signal laser L3 and the third pump laser P3 can be selected from one of rare earth-doped materials such as ytterbium-doped materials, erbium-doped materials, thulium-doped materials, neodymium-doped materials, holmium-doped materials, samarium-doped materials, praseodymium-doped materials, and erbium-ytterbium co-doped materials. Preferably, the third rare earth ion material should be different from the first rare earth ion material, and the third rare earth ion material should be different from the second rare earth ion material, so as to emit different annular layered and controllable wavelengths. That is, the wavelength of the third signal laser L3 is different from the wavelength of the second signal laser L2, and that of the third signal laser L3 is different from the wavelength of the first signal laser L1.

[0036] Preferably, the nth rare earth ion material corresponding to the nth signal laser Ln and the nth pump laser Pn can be selected from one of ytterbium-doped materials, erbium-doped materials, thulium-doped materials, neodymium-doped materials, holmium-doped materials, samarium-doped materials, praseodymium-doped materials, and erbium-ytterbium co-doped materials. Preferably, the nth rare earth ion material should be different from the rare earth ion materials corresponding to the signal lasers and pump lasers in other parts of the beamforming region, so as to emit different wavelengths that can be controlled by annular layering.

[0037] The wavelength of the pump light in the relatively inner portion of the beam-forming region is smaller than the wavelength of the pump light in the relatively outer portion of the beam-forming region surrounding it, and / or the wavelength of the signal light in the relatively inner portion of the beam-forming region is smaller than the wavelength of the signal light in the relatively outer portion of the beam-forming region surrounding it.

[0038] Preferably, the signal optical fiber in the first portion of the beam-forming region is a passive matching optical fiber capable of transmitting corresponding laser light excited by doped ytterbium ions.

[0039] Preferably, the pump fiber in the first portion of the cluster region is a coupled output fiber of a pump source that outputs laser light capable of pumping the ytterbium-doped material. Preferably, the pump source is a laser diode (LD) pump source.

[0040] Preferably, the signal optical fiber in the second portion of the beam-forming region is a passive matching optical fiber capable of transmitting corresponding laser light excited by erbium-doped ions.

[0041] Preferably, the pump fiber in the second portion of the cluster region is a coupled output fiber of a pump source that outputs laser light capable of pumping the Erbium-Ytterbium co-doped ion material. Preferably, the pump source is an optical laser diode (LD) pump source.

[0042] Preferably, the signal optical fiber in the third portion of the beam-forming region is a passive matching optical fiber capable of transmitting corresponding laser light excited by thulium ions.

[0043] Preferably, the pump fiber in the third portion of the cluster region is a coupled output fiber of a pump source that outputs a laser capable of pumping the thulium-doped material. Preferably, the pump source is an optical laser diode (LD) pump source.

[0044] Preferably, when there is an nth part of the beam-forming region (n>3, a positive integer), suitable signal fibers, pump fibers and pump sources can be selected.

[0045] Preferably, the refractive index of the silica low-refractive-index glass tube is lower than the refractive index of the cladding of the pump fiber (herein, lower than the refractive index of the cladding of the pump fiber means lower than the refractive index of the claddings of all pump fibers).

[0046] Preferably, the refractive index of the quartz low-refractive-index glass tube is lower than the refractive index of the cladding of the signal optical fiber (here, lower than the refractive index of the cladding of the signal optical fiber means lower than the refractive index of the cladding of all signal optical fibers).

[0047] Preferably, a low-refractive-index quartz glass tube is positioned between various sections of the clustering region. For example, a low-refractive-index quartz glass tube is positioned between the first and second sections of the clustering region; between the second and third sections of the clustering region; and between the (n-1)th section and the nth section of the clustering region. The outermost section of the clustering region for the signal and pump light output fibers comprises a low-refractive-index quartz glass tube. Preferably, the low-refractive-index quartz glass tube is a fluorine- or boron-doped low-refractive-index glass tube.

[0048] The clustering area includes the first part of the clustering area, the second part of the clustering area, and the third part of the clustering area; the first part of the clustering area is basically a circular area, and the outer diameter of the first part of the clustering area is basically 375μm; the second part of the clustering area is basically an annular area, the inner diameter of the second part of the clustering area is 425μm, and the outer diameter of the second part of the clustering area is 675μm; the third part of the clustering area is basically an annular area, the inner diameter of the third part of the clustering area is 725μm, and the outer diameter of the third part of the clustering area is 975μm (the inner diameter and outer diameter mentioned here refer to the diameter).

[0049] Preferably, the first rare earth ion material may be an ytterbium ion-doped material, the first signal laser L1 corresponds to a single-mode signal laser that can be emitted by the doped ytterbium ions, the first pump laser P1 corresponds to a multi-mode pump laser that can be absorbed by the doped ytterbium ions, and the output peak of the ytterbium ions may be substantially 1080 nm, and its absorption peak may be substantially 915 nm or 976 nm; that is, the peak wavelength of the first signal laser is substantially 1080 nm, and the peak wavelength of the first pump laser is substantially 915 nm or substantially 976 nm.

[0050] Preferably, the second rare earth ion material can be an erbium-doped ytterbium co-doped ion material, the second signal laser L2 corresponds to the single-mode signal laser emitted by the doped erbium ions, and the second pump laser P2 corresponds to the multi-mode pump laser absorbed by the erbium-doped ytterbium co-doped ions. The output peak of the erbium-doped ytterbium co-doped ions can be basically 1550nm, and its optional absorption peak can be basically 940 or 980nm; that is, the peak wavelength of the second signal laser is basically 1550nm, and the peak wavelength of the second pump laser is basically 940nm or basically 980nm.

[0051] Preferably, the third rare earth ion material can be a thulium ion-doped material, the third signal laser L3 corresponds to the single-mode signal laser emitted by the doped thulium ions, the third pump laser P3 corresponds to the multi-mode pump laser absorbed by the doped thulium ions, the output peak of the doped thulium ions can be basically 1940nm or basically 1980nm, and its optional absorption peak can be basically 793nm or 1550nm; that is, the peak wavelength of the second signal laser can be basically 1940nm or basically 1980nm, and the peak wavelength of the second pump laser can be basically 793nm or 1550nm.

[0052] Preferably, the nth rare earth dopant ion material can be other dopant ion materials available for fiber lasers, and the nth signal laser Ln and the nth pump laser Pn correspond to the single-mode signal laser and multi-mode pump laser emitted and absorbed by the nth rare earth dopant ion.

[0053] A clustering tapered area is set at the rear side of the clustering area: in order to achieve low insertion loss coupling between the clustering area and the multi-core doped active optical fiber, the clustering area needs to be tapered.

[0054] Preferably, the bundled tapered region 3 is obtained by performing a tapered process on the signal light and pump light output fiber bundled region 2 .

[0055] In order to reduce the loss of light energy, preferably, the taper length satisfies the insulating taper condition: the diffraction angle within the optical fiber ≥ the optical fiber taper angle.

[0056] Preferably, the taper ratio of this section is 2:1.

[0057] Preferably, for efficient coupling, after the optical fiber is tapered, the tapered end is cut, and then it is fused with the multi-core doped active optical fiber. The fusion splicing method can be CO2 laser, electrode discharge, hydrogen-oxygen flame, graphite heating and other fusion splicing methods.

[0058] Preferably, the tapered end can be cut using a fiber cleaver.

[0059] In order to match the clustering region, the multi-core doped active fiber includes multiple doped parts. That is, when the clustering region includes a plurality of m parts, the multi-core doped active fiber includes the same number of m doped parts.

[0060] The cluster area consists of three parts, namely, the first cluster area part, the second cluster area part, and the third cluster area part.

[0061] The multi-core doped active optical fiber includes multiple rare earth ion-doped regions, preferably at least two rare earth ion-doped regions. Preferably, it has an innermost central rare earth ion-doped region, while the outer rare earth ion-doped regions can be annular regions. The innermost rare earth ion-doped region is a basic circular region, while the other rare earth ion-doped regions, i.e., the outer rare earth ion-doped regions, are annular regions. Preferably, they include at least one central doped ion region and one annular rare earth ion-doped region. That is, the multi-core in the multi-core doped active optical fiber refers to an amplified region having at least two rare earth ion doped regions. Preferably, the multi-core doped active optical fiber includes three rare earth ion-doped regions, preferably, the multi-core doped active optical fiber includes a central rare earth ion-doped region and two annular rare earth ion-doped regions.

[0062] Preferably, it can be mainly composed of three parts 1, 2, and 3. The third region is a region doped with rare earth thulium ions, preferably a substantially annular region. The second region 2 is a region co-doped with rare earth erbium and ytterbium ions, preferably a substantially annular region. The first region is a region doped with ytterbium ions, preferably a substantially circular region. The inner diameter of the third region is 362.5 μm, and the outer diameter of the third region is 487.5 μm. The inner diameter of the second region is 212.5 μm, and the outer diameter of the second region is 337.5 μm. The inner diameter of the first doped region is 62.5 μm, and the outer diameter of the first doped region is 187.5 μm. The composition of parts 4, 5, 6, and 7 is quartz.

[0063] The first region is basically a circular region, doped with a first rare earth ion, and is used to amplify the first signal light; the second region surrounds the first region, the second region is basically a (circular) ring region, doped with a second rare earth ion, and is used to amplify the second signal light; the third region surrounds the second region, the second region is basically a (circular) ring region, doped with a third rare earth ion, and is used to amplify the third signal light.

[0064] That is, a quartz layer is provided between the first region and the second region. The thickness of the quartz layer is preferably the inner diameter of the second region minus the outer diameter of the first region, that is, the thickness on one side is 12.5 μm, and the thickness on both sides is 25 μm in total.

[0065] A quartz layer is provided between the second region and the third region. The thickness of the quartz layer is preferably the inner diameter of the third region minus the outer diameter of the second region, with a thickness of 12.5 μm on one side and a total thickness of 25 μm on both sides.

[0066] A quartz layer is provided outside the third region. The thickness of the quartz layer is preferably 12.5 μm on one side and 25 μm in total on both sides.

[0067] A quartz core region is arranged inside the first region. The quartz core region is substantially a circular region, and a diameter of the quartz core region is substantially the inner diameter of the first doped region.

[0068] According to the design, the refractive index of the quartz layer is lower than that of the first region, the refractive index of the quartz layer is lower than that of the second region, and the refractive index of the quartz layer is lower than that of the third region. Preferably, the refractive index of the quartz core region is lower than that of the first doped region.

[0069] Preferably, the optical fiber in the middle of the first part of the cluster region is a pump fiber.

[0070] Preferably, in the multi-wavelength amplified ring laser output by the multi-core doped active optical fiber, the first signal light L1 and the first pump light P1 and the output laser part corresponding to the first region are the first output light part Q1; the second signal light L2 and the second pump light P2 and the output laser part corresponding to the second region are the second output light part Q1; the third signal light L3 and the third pump light P3 and the output laser part corresponding to the third region are the third output light part Q3; when the part of the beam area exceeds 3 parts, the nth signal light Ln and the nth pump light Pn and the output laser part corresponding to the nth region are the nth output light part Qn (n>3, which is a positive integer).

[0071] Through the design of optical fiber structure, the number of core areas of multi-core doped optical fiber can be increased to increase the types of doped rare earth ions, such as neodymium, holmium, samarium, praseodymium, etc.

[0072] Preferably, the signal fiber is a few-mode fiber with a core diameter greater than 15 μm and a cladding diameter greater than 150 μm. Preferably, the pump fiber is a multi-mode fiber with a core diameter greater than 133 μm and a cladding diameter greater than 153 μm.

[0073] The beneficial effects of the present invention are:

[0074] (1) The structure of the multi-layer fiber core is creatively modified, and the designed fiber bundle structure and the unique multi-core doped fiber are cleverly combined to provide a laser that outputs a composite wavelength annular spot laser. The coupling efficiency of the input pump light is high, the input signal pattern is more stable, and the input signal is more uniform in spatial distribution. It can greatly increase the laser power while greatly reducing energy loss. This is the object of research in the field of high-power laser processing. At the same time, the rational structural arrangement makes the output light beam quality higher, the pattern more stable, and reduces nonlinear effects, meeting the needs of high-power laser processing.

[0075] (2) It is capable of high-energy multi-wavelength laser ring output, which meets the requirements of some specific processing application scenarios in high-power laser processing, such as some scenarios in precision welding, etc., and realizes ring-shaped multi-wavelength composite laser output with good light field symmetry. When the number and type of output wavelengths need to be adjusted, there is no need to change the settings and structures in a complicated way. It only needs to turn on or off the signal laser and pump laser of the corresponding wavelength to replace them with another uniform ring laser with central symmetry.

[0076] (3) A quartz low-refractive-index layer is provided in the clustering region. In the multi-core doped active optical fiber, a plurality of annular rare-earth ion-doped regions are included. A quartz layer is provided between any two rare-earth ion-doped regions to reduce the interference between each clustering region and each rare-earth ion-doped region and to improve the utilization rate of the laser. A quartz layer is provided outside the outermost rare-earth ion-doped region to prevent laser leakage from causing harm to people.

[0077] (4) The wavelength of the signal laser in the inner layer is set to be smaller than that of the signal laser in the outer layer. Then, the pump laser or excitation light energy that occasionally overflows from the inner layer can also be absorbed by the rare earth ions in the outer layer, thereby improving the utilization rate of the pump light energy. This not only reduces costs at high energy output, but also reduces the heat generation and heat load of the entire gain fiber, preventing nonlinear effects caused by overheating.

[0078] (5) According to the design of the optical fiber structure, each area has a numerical aperture. At the same time, each thulium-doped, erbium-ytterbium, and ytterbium laser that needs to be amplified and the corresponding pump laser are respectively restricted to transmission in areas 1, 2, and 3. Therefore, the amplification of the above three lasers is spatially separated. Therefore, the amplification size of each laser can be controlled by controlling the injection size of the signal light and the pump light in areas 1, 2, and 3. The amplification structure is essentially a Mopa amplification structure. Therefore, it has the characteristic that the amplified output laser depends on the beam quality of the signal laser. In the present invention, thulium, erbium, and ytterbium single-mode lasers are used as signal light, so that high beam quality and high output power output can be obtained.

[0079] (6) The inventors can replace the signal fiber with a few-mode laser fiber to solve the mode mismatch problem during the pumping process. At the same time, the core diameter of the few-mode signal fiber and the core diameter of the multi-mode pump fiber can be increased. Through the fiber structure design, the number of core regions of the multi-core doped fiber can be increased to increase the number of rare earth ion doping species, such as neodymium, holmium, samarium, praseodymium, etc.

[0080] (7) The number of parts of the beam-gathering region is at least three, that is, the beam-gathering region should at least include the first beam-gathering region, the second beam-gathering region, and the third beam-gathering region. Compared with the case where there are only two parts, when the beam-gathering region includes three or more parts, it can be simply controlled to emit a plurality of combinations of laser wavelength ring outputs, such as the combination of the second signal light and the third signal light, the combination of the first signal light and the third signal light (this combination is also a composite laser with greater spatial separation, which has good application in precision cladding processing), the first signal light and the second signal light, the first signal light and the second signal light and the third signal light, etc. In this way, more processing functions can be realized through simple and quick operation, and the power of the total output light can be greatly improved, which greatly exceeds the power level and functionality of the ring laser output of the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 It is a structural schematic diagram of the present invention.

[0082] Figure 2 It is a cross-sectional schematic diagram of the signal light and pump light output fiber bundling area of ​​the present invention.

[0083] Figure 3 Schematic cross-sectional view of a specific embodiment of the signal optical fiber and the pump optical fiber of the present invention.

[0084] Figure 4 Schematic cross-sectional view of the multi-core doped active optical fiber of the present invention. DETAILED DESCRIPTION

[0085] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific implementation methods.

[0086] like Figure 1 As shown, the present invention discloses a multi-doped rare earth ion multi-wavelength fiber laser, which can realize high-power composite wavelength fiber laser output with independently controllable output power of multiple wavelengths.

[0087] The composite wavelength fiber laser uses a multi-core doped active fiber as a gain fiber and combines the signal light + pump light combiner to achieve the amplified output of the signal light (see attached Figure 1 ).

[0088] The composite wavelength fiber laser mainly consists of four parts: signal light and pump light module, signal light and pump light output fiber bundling area, bundling tapered area, and multi-core doped active fiber.

[0089] The signal light and pump light module includes a signal light module and a pump light module. The signal light module can output the signal laser to be amplified. Preferably, the signal light module can simultaneously output two wavelengths of signal laser to be amplified, namely the first signal laser L1 and the second signal laser L2. The first signal laser or L1 and the second signal laser L2 can be output from the signal light module through their respective waveguide output structures or spatial light output structures; preferably, the signal light module can simultaneously output three wavelengths of signal laser to be amplified, namely the first signal laser L1, the second signal laser L2, and the third signal laser L3. The first signal laser or L1, the second signal laser L2, and the third signal laser L3 can be output from the signal light module through their respective waveguide output structures or spatial light output structures. The laser L3 can be output from the signal light module through their respective waveguide output structures or spatial light output structures; preferably, the signal light module can simultaneously output n wavelengths (n>3, a positive integer) of signal lasers to be amplified, namely the first signal laser L1, the second signal laser L2, the third signal laser L3, (the fourth signal laser L4)...the nth signal laser Ln, and the first signal laser L1, the second signal laser L2, the third signal laser L3, (the fourth signal laser L4)...the nth signal laser Ln can be output from the signal light module through their respective waveguide output structures or spatial light output structures.

[0090] The pump light module outputs the corresponding pump light required to achieve signal light amplification. Preferably, the pump light includes pump lasers of multiple wavelengths corresponding to the multiple wavelengths of signal light. Preferably, when the signal light module can simultaneously output two wavelengths of signal lasers to be amplified, namely the first signal laser L1 and the second signal laser L2, the pump light module outputs two wavelengths of corresponding pump light, namely the first pump laser P1 and the second pump laser P2; preferably, the signal light module can simultaneously output three wavelengths of signal lasers to be amplified, namely the first signal laser L1, the second signal laser L2, and the third signal laser L3. When the laser L3 is used, the pump light module outputs corresponding pump lights of three wavelengths, namely the first pump laser P1, the second pump laser P2, and the third pump laser P3; preferably, the signal light module can simultaneously output n wavelengths (n>3, a positive integer) of signal lasers to be amplified, namely the first signal laser L1, the second signal laser L2, the third signal laser L3, (the fourth signal laser L4)...When the nth signal laser Ln is used, the pump light module outputs corresponding pump lights of n wavelengths, namely the first pump laser P1, the second pump laser P2, the third pump laser P3...the nth pump laser Pn.

[0091] The signal laser corresponds to the laser that can be emitted and / or amplified by the multi-core optical fiber doped with rare earth ion materials, while the pump laser is a pump laser that can be absorbed by the rare earth ions and cause the ion population to flip. Preferably, the first signal laser L1 corresponds to the first pump laser P1, the first rare earth ion material absorbs the first pump laser P1 and flips the ion population, and emits the amplified first signal laser L1; preferably, the second signal laser L2 corresponds to the second pump laser P2, the second rare earth ion material absorbs the second pump laser P2 and flips the ion population, and emits the amplified second signal laser L2; preferably, the third signal laser L3 corresponds to the third pump laser P3, the third rare earth ion material absorbs the third pump laser P3 and flips the ion population, and emits the amplified third signal laser L3; preferably, the nth signal laser Ln corresponds to the nth pump laser Pn, the nth rare earth ion material absorbs the nth pump laser Pn and flips the ion population, and emits the amplified nth signal laser Ln (n>3, a positive integer).

[0092] Preferably, the power of the first pump laser, the second pump laser, the third pump laser...the nth signal laser is independently adjustable, that is, the power of the first pump laser is independently adjustable, that is, the power of the second pump laser is independently adjustable, that is, the power of the third pump laser is independently adjustable, that is, the power of the nth pump laser is independently adjustable (n>3, a positive integer), so as to achieve independent controllability of the output light of each wavelength.

[0093] Preferably, the signal laser may be a single-mode signal laser to improve the beam quality of the output light.

[0094] Preferably, the pump laser may be a multi-mode pump laser, which can enable the rare earth ions in various locations of the gain material to be excited in a well-balanced manner and expand the power scenario.

[0095] The signal light and pump light output fiber cluster area includes signal fiber, pump fiber (such as attached Figure 2 ) which bundles the signal fiber and the pump fiber. Preferably, to stably secure the signal fiber and the pump fiber bundle, a tube is also included to enclose the signal fiber and the pump fiber. To facilitate subsequent tapering, the tube enclosing the signal fiber and the pump fiber is a quartz glass tube.

[0096] For convenience, the signal light and pump light output fiber bundling area is referred to as the bundling area below.

[0097] Preferably, because the energy of the pump light is very high and the cladding of the pump fiber is relatively thin, to reduce light energy loss and improve light efficiency, the quartz glass tube is a low-refractive-index quartz glass tube. Using a low-refractive-index quartz glass tube can effectively confine the pump light within the glass tube in the subsequent tapering region, preventing light loss. The low refractive index in the low-refractive-index quartz glass tube refers to a refractive index of the quartz glass tube lower than the core refractive index of the pump fiber (here, lower than the core refractive index of the pump fiber means lower than the core refractive index of all pump fibers). At the same time, although the energy of the signal light is low and the cladding of the signal fiber is thick, the probability of signal light loss is low. However, due to the subsequent tapering process, there is still a possibility of signal light loss in the tapering region. Therefore, it is best to better confine the signal light. Preferably, the refractive index of the quartz glass tube is also lower than the core refractive index of the signal fiber (here, lower than the core refractive index of the signal fiber means lower than the core refractive index of all signal fibers).

[0098] Preferably, the quartz low-refractive-index glass tube can be manufactured by doping. Preferably, in order to better match the optical fiber in the tapered region, the quartz low-refractive-index glass tube is preferably a fluorine- or boron-doped quartz low-refractive-index glass tube.

[0099] Preferably, the signal fiber can be a single-mode fiber to obtain a single-mode signal light with high beam quality. Preferably, the signal fiber is a 10 / 125 single-mode fiber (such as the attached Figure 3 ).

[0100] Preferably, the pump fiber adopts a multimode pump fiber that can accommodate high-power multimode light. Preferably, the pump fiber has a parameter of 105 / 125 / 0.22 (as shown in the attached figure). Figure 3 ), the use of this multimode pump fiber will increase the injection capability of the pump laser.

[0101] Preferably, in order to enable different laser partition pumping to improve pumping efficiency, the beam zone is divided into multiple regional parts, preferably, it can include the first part of the beam zone and the second part of the beam zone; preferably, it can include the first part of the beam zone, the second part of the beam zone, and the third part of the beam zone; preferably, it can include the first part of the beam zone, the second part of the beam zone, the third part of the beam zone, and... the nth part of the beam zone.

[0102] Preferably, each part includes a signal optical fiber and a pump optical fiber.

[0103] Preferably, in order to better transmit signal light and improve the quality of output signal laser, so that the signal laser is more matched with the active optical fiber, preferably, the signal optical fiber is a passive matching optical fiber that can transmit the corresponding laser excited by the corresponding ions.

[0104] Preferably, the pump fiber is a pump source coupling output fiber in the pump optical module.

[0105] Preferably, when a multi-wavelength laser is output, in high-power application scenarios such as welding, it is often required that the multi-wavelength lasers have the same output axis. In order to solve this problem and to achieve the individual control of the laser components of the output composite wavelength laser, when only part of the multi-wavelength laser is used, the output lasers should have the same axis and symmetrical distribution. Preferably, the beam zone adopts the following method: Figure 2 The various parts of the cluster area are arranged layer by layer starting from the center and moving outwards.

[0106] Preferably, the cluster area has, from the inside to the outside, a first cluster area part, a second cluster area part, a third cluster area part, ... an nth cluster area area (n>3, a positive integer).

[0107] Preferably, the first part of the cluster area is a circular area in the center, the second part of the cluster area is an annular area surrounding the first part of the cluster area, the third part of the cluster area is an annular area surrounding the second part of the cluster area,... the nth part of the cluster area (n>3, a positive integer) is an annular area surrounding the (n-1)th part of the cluster area.

[0108] Preferably, in order to achieve high-quality laser output, the second part of the beam area is a circular area surrounding the first part of the beam area, the third part of the beam area is a circular area surrounding the second part of the beam area,... the nth part of the beam area (n>3, a positive integer) is a circular area surrounding the (n-1)th part of the beam area.

[0109] Each portion of the cluster region preferably includes a respective signal fiber and its corresponding pump fiber.

[0110] Preferably, the first part of the clustering region includes a first signal fiber and a first pump fiber corresponding thereto, the first signal fiber is used to transmit the first signal laser L1, the first pump fiber is used to transmit the first pump laser P1, preferably, the number of the first signal fibers is one or more, preferably, the number of the first signal fibers is two or more, preferably, the number of the first pump fibers is one or more, preferably, the number of the first pump fibers is two or more; preferably, the second part of the clustering region includes a second signal fiber and a second pump fiber corresponding thereto, the second signal fiber is used to transmit the second signal laser L2, the second pump fiber is used to transmit the second pump laser P2, preferably, the number of the second signal fibers is one or more, preferably, the number of the second signal fibers is two or more, preferably, the number of the second pump fibers is one or more, preferably, the number of the second pump fibers is two or more; Preferably, the third part of the clustering area includes a third signal fiber and a corresponding third pump fiber, the third signal fiber is used to transmit the third signal laser L3, and the third pump fiber is used to transmit the third pump laser P3. Preferably, the number of the third signal fibers is one or more, preferably, the number of the third signal fibers is two or more, preferably, the number of the third pump fibers is one or more, preferably, the number of the third pump fibers is two or more; preferably, the nth part of the clustering area includes an nth signal fiber and a corresponding nth pump fiber, the nth signal fiber is used to transmit the nth signal laser Ln, and the nth pump fiber is used to transmit the nth pump laser Pn. Preferably, the number of the nth signal fibers is one or more, preferably, the number of the nth signal fibers is two or more, preferably, the number of the nth pump fibers is one or more, preferably, the number of the nth pump fibers is two or more.

[0111] Preferably, the number of parts of the cluster area should be at least greater than two, that is, the cluster area should at least include a first cluster area part, a second cluster area part, and a third cluster area part (see Figure 2 In an embodiment), compared with the case where there are only two parts (i.e., only the first part of the beam-forming area and the second part of the beam-forming area), when the beam-forming area includes three parts or more, it can be simply controlled to emit a plurality of combinations of laser wavelength ring outputs (rather than only one combination as in the case of two parts), such as the second signal light and the third signal light combination, the first signal light and the third signal light combination (this combination is also a composite laser with greater spatial separation, which has good application in precision cladding processing), the first signal light and the second signal light, the first signal light and the second signal light and the third signal light, etc., so that more processing functions can be realized with simple and quick operation, and the power of the total output light can be greatly improved, which greatly exceeds the power level and functionality of the ring laser output in the prior art.

[0112] Preferably, the first rare earth ion material corresponding to the first signal laser L1 and the first pump laser P1 can be selected from one of ytterbium-doped material, erbium-doped material, thulium-doped material, neodymium-doped material, holmium-doped material, samarium-doped material, praseodymium-doped material, erbium-ytterbium co-doped material and the like.

[0113] Preferably, the second rare earth ion material corresponding to the second signal laser L2 and the second pump laser P2 can be selected from one of ytterbium-doped materials, erbium-doped materials, thulium-doped materials, neodymium-doped materials, holmium-doped materials, samarium-doped materials, praseodymium-doped materials, and erbium-ytterbium co-doped materials. Preferably, the second rare earth ion material should be different from the first rare earth ion material to emit different, controllable annular layered wavelengths. That is, the wavelength of the second signal laser L2 is different from the wavelength of the first signal laser L1.

[0114] Preferably, the third rare earth ion material corresponding to the third signal laser L3 and the third pump laser P3 can be selected from one of ytterbium-doped materials, erbium-doped materials, thulium-doped materials, neodymium-doped materials, holmium-doped materials, samarium-doped materials, praseodymium-doped materials, and erbium-ytterbium co-doped materials. Preferably, the third rare earth ion material should be different from the first rare earth ion material, and the third rare earth ion material should be different from the second rare earth ion material, so as to emit different annular layered and controllable wavelengths. That is, the wavelength of the third signal laser L3 is different from the wavelength of the second signal laser L2, and that of the third signal laser L3 is different from the wavelength of the first signal laser L1.

[0115] Preferably, the nth rare earth ion material corresponding to the nth signal laser Ln and the nth pump laser Pn can be selected from one of ytterbium-doped materials, erbium-doped materials, thulium-doped materials, neodymium-doped materials, holmium-doped materials, samarium-doped materials, praseodymium-doped materials, and erbium-ytterbium co-doped materials. Preferably, the nth rare earth ion material should be different from the rare earth ion materials corresponding to the signal lasers and pump lasers in other parts of the beamforming region, so as to emit different wavelengths that can be controlled by annular layering.

[0116] Because the arrangement of the active doping regions in a multi-core doped active fiber is best aligned with the arrangement of the various parts of the cluster region, the doping regions in the multi-core doped active fiber are also arranged layer by layer, starting from the center and working outward. During high-energy laser pumping, the pump light and excitation light in the inner regions of the tapered region and multi-core doped active fiber are more likely to escape outward, thus easily wasting pump light and reducing laser efficiency. Therefore, in order to improve the utilization efficiency of the pump light and improve the laser efficiency, it is preferred to arrange the various parts of the beam region in the following manner: the wavelength of the pump light of the relatively inner portion of the beam region is smaller than the wavelength of the pump light of the relatively outer portion of the beam region surrounding it; the wavelength of the first pump laser P1 in the inner layer is smaller than the wavelength of the second pump laser P2 located in the second portion of the beam region surrounding it; the wavelength of the second pump laser P2 located in the second portion of the beam region is smaller than the wavelength of the third pump laser P3 located in the third portion of the beam region; the wavelength of the pump laser P(n-1) located in the (n-1)th portion of the beam region is smaller than the wavelength of the pump laser P(n-1) located in the nth portion of the beam region The wavelength of the pump laser Pn of the beam section is smaller than that of the pump laser Pn of the beam section (n>3, which is a positive integer); and / or, the wavelength of the signal light in the relatively inner portion of the beam section is smaller than the wavelength of the signal light in the relatively outer portion of the beam section surrounding it, the wavelength of the first signal laser L1 in the inner layer is smaller than the wavelength of the second signal laser L2 in the second portion of the beam section surrounding it; the wavelength of the second signal laser L2 in the second portion of the beam section is smaller than the wavelength of the third signal laser L3 in the third portion of the beam section; the wavelength of the signal laser L(n-1) in the (n-1)th portion of the beam section is smaller than the wavelength of the pump laser Pn in the nth portion of the beam section (n>3, which is a positive integer). Because the wavelength of the inner pump laser is smaller than that of the outer pump laser, and / or the wavelength of the inner signal laser is smaller than that of the outer signal laser, occasional overflow of the inner pump laser or excitation light energy can be absorbed by the outer rare earth ions, improving the utilization of the pump light energy. This not only reduces costs at high energy output, but also reduces heat generation and heat load of the entire gain fiber, preventing nonlinear effects caused by overheating. Furthermore, the above arrangement can also take into account the reasonable distribution of laser modes in the multi-core doped active fiber.

[0117] Preferably, the following specific implementations can be selected to implement the above concept.

[0118] Preferably, the signal optical fiber in the first portion of the beam-forming region is a passive matching optical fiber capable of transmitting corresponding laser light excited by doped ytterbium ions.

[0119] Preferably, the pump fiber in the first portion of the cluster region is a coupled output fiber of a pump source that outputs a laser capable of pumping ytterbium-doped materials. Preferably, the pump source is a laser diode (LD) pump source that outputs a pump laser capable of pumping ytterbium-doped materials.

[0120] Preferably, the signal optical fiber in the second portion of the beam-forming region is a passive matching optical fiber capable of transmitting corresponding laser light excited by erbium-doped ions.

[0121] Preferably, the pump fiber in the second portion of the cluster region is a coupled output fiber of a pump source that outputs a laser capable of pumping the erbium-ytterbium co-doped ion material. Preferably, the pump source is a laser diode (LD) pump source that outputs a pump laser capable of pumping the erbium-ytterbium co-doped ion material.

[0122] Preferably, the signal optical fiber in the third portion of the beam-forming region is a passive matching optical fiber capable of transmitting corresponding laser light excited by thulium ions.

[0123] Preferably, the pump fiber in the third portion of the cluster region is a coupled output fiber of a pump source that outputs a laser capable of pumping thulium-doped ion materials. Preferably, the pump source is a laser diode (LD) pump source that outputs a pump laser capable of pumping thulium-doped ion materials.

[0124] Preferably, when there is an nth part of the beam-forming region (n>3, a positive integer), suitable signal fibers, pump fibers and pump sources can be selected.

[0125] Since the absorption peak of the ytterbium ion-doped material under normal conditions is 915nm or 976nm, and the output peak is 1080nm, the absorption peak of the erbium-ytterbium co-doped ion material under normal conditions is 940nm or 980nm, and the output peak is 1550nm, the absorption peak of the thulium ion-doped material under normal conditions can be basically 793nm or 1550nm, and the output peak is 1940nm or 1980nm, which meet the above-mentioned requirements for the wavelengths of pump light and excitation light. Therefore, the arrangement of the above-mentioned bundled optical fibers can basically perfectly meet the above-mentioned requirements of improving energy utilization, reducing heat generation, and taking into account the reasonable distribution of laser modes in multi-core doped active optical fibers.

[0126] The inventors recognized that in the clustered tapered region, due to the tapering of the optical fiber, the possibility of laser light overflowing from the optical fiber cladding increases. If the overflowing pump light can be made to undergo total reflection at the interface between the cladding and the quartz glass tube, the pump light will be better confined and prevented from entering other areas and affecting the properties of other areas. Therefore, in order to prevent interference and improve the efficiency of pump light use, the pump light caused by the tapering is reflected back from the interface between the cladding of the pump fiber and the quartz glass tube. Preferably, the refractive index of the low-refractive-index quartz glass tube is lower than the refractive index of the cladding of the pump fiber (here, lower than the refractive index of the cladding of the pump fiber means lower than the refractive index of the cladding of all pump fibers).

[0127] Similarly, if the risk of interference caused by leakage of signal light is taken into consideration, preferably, the refractive index of the quartz low-refractive-index glass tube is lower than the refractive index of the cladding of the signal optical fiber (here, lower than the refractive index of the cladding of the signal optical fiber means lower than the refractive index of the cladding of all signal optical fibers).

[0128] Based on the above, in order to reduce interference between the lasers in the clustering region and the clustering tapered region, and to further improve energy utilization and output laser quality, preferably, quartz low-refractive-index glass tubes are placed between the various parts of the clustering region. For example, a quartz low-refractive-index glass tube is placed between the first and second parts of the clustering region; a quartz low-refractive-index glass tube is placed between the second and third parts of the clustering region; and a quartz low-refractive-index glass tube is placed between the (n-1)th part of the clustering region and the nth part of the clustering region. Of course, the outermost part of the signal light and pump light output fiber clustering region includes a quartz low-refractive-index glass tube, which has been described previously and will not be repeated here. Preferably, the quartz low-refractive-index glass tube is a fluorine-doped low-refractive-index glass tube.

[0129] The following describes a specific embodiment. The cluster area includes a first cluster area portion, a second cluster area portion, and a third cluster area portion. The first cluster area portion is substantially a circular area (corresponding to Figure 2 The outer diameter of the first part of the clustering area is basically 375 μm; the second part of the clustering area is basically an annular area (corresponding to Figure 2 b area), preferably, the second part of the cluster area is basically a circular ring area, the inner diameter of the second part of the cluster area is 425 μm, and the outer diameter of the second part of the cluster area is 675 μm; the third part of the cluster area is basically a ring area (corresponding to Figure 2 a area), preferably, the third part of the clustering area is basically a circular area, the inner diameter of the third part of the clustering area is 725 μm, and the outer diameter of the third part of the clustering area is 975 μm (the inner diameter and outer diameter mentioned above refer to diameters).

[0130] In a specific embodiment, for example, the quartz low-refractive-index glass tube between the first portion of the focusing region and the second portion of the focusing region corresponds to Figure 2 The thickness of the fluorine-doped low-refractive-index glass tube in the f region is preferably 25 μm. The quartz low-refractive-index glass tube between the second and third parts of the focusing region corresponds to Figure 2 The thickness of the fluorine-doped low-refractive-index glass tube in the e region is preferably 25 μm. The quartz low-refractive-index glass tube outside the third part of the clustering region corresponds to Figure 2The thickness of the fluorine-doped low-refractive-index glass tube in region d is preferably 25 μm. This serves to limit the transmission of signal and pump light within each of regions a, b, and c, ensuring that both signal and pump light can be transmitted within their respective regions without causing cross-transmission of signal and pump light between different regions.

[0131] Since the wavelengths corresponding to the laser pump and output cannot be precisely determined, they are usually close to a certain value. Therefore, the following description often uses "basically" to refer to a certain wavelength.

[0132] Preferably, the first rare earth ion material may be an ytterbium ion-doped material, the first signal laser L1 corresponds to a single-mode signal laser that can be emitted by the doped ytterbium ions, the first pump laser P1 corresponds to a multi-mode pump laser that can be absorbed by the doped ytterbium ions, and the output peak of the ytterbium ions may be substantially 1080 nm, and its absorption peak may be substantially 915 nm or 976 nm; that is, the peak wavelength of the first signal laser is substantially 1080 nm, and the peak wavelength of the first pump laser is substantially 915 nm or substantially 976 nm.

[0133] Preferably, the second rare earth ion material can be an erbium-doped ytterbium co-doped ion material, the second signal laser L2 corresponds to the single-mode signal laser emitted by the erbium-doped co-doped ions, and the second pump laser P2 corresponds to the multi-mode pump laser absorbed by the erbium-doped ytterbium co-doped ions. The output peak of the erbium-doped ytterbium co-doped ions can be basically 1550nm, and its optional absorption peak can be basically 940 or 980nm; that is, the peak wavelength of the second signal laser is basically 1550nm, and the peak wavelength of the second pump laser is basically 940nm or basically 980nm.

[0134] Preferably, the third rare earth ion material can be a thulium ion-doped material, the third signal laser L3 corresponds to the single-mode signal laser emitted by the doped thulium ions, the third pump laser P3 corresponds to the multi-mode pump laser absorbed by the doped thulium ions, the output peak of the doped thulium ions can be basically 1940nm or basically 1980nm, and its optional absorption peak can be basically 793nm or 1550nm; that is, the peak wavelength of the second signal laser can be basically 1940nm or basically 1980nm, and the peak wavelength of the second pump laser can be basically 793nm or 1550nm.

[0135] Preferably, the nth rare earth dopant ion material can be other dopant ion materials available for fiber lasers, and the nth signal laser Ln and the nth pump laser Pn correspond to the single-mode signal laser and multi-mode pump laser emitted and absorbed by the nth rare earth dopant ion.

[0136] A clustering tapered area is set at the rear side of the clustering area: in order to achieve low insertion loss coupling between the clustering area and the multi-core doped active optical fiber, the clustering area needs to be tapered.

[0137] Preferably, the bundled tapered region 3 is obtained by performing a tapered process on the signal light and pump light output fiber bundled region 2 .

[0138] In order to reduce the loss of light energy, preferably, the taper length satisfies the insulating taper condition: the diffraction angle within the optical fiber ≥ the optical fiber taper angle.

[0139] Preferably, the taper ratio of this section is 2:1.

[0140] Preferably, for efficient coupling, after the optical fiber is tapered, the tapered end is cut, and then it is fused with the multi-core doped active optical fiber. The fusion splicing method can be CO2 laser, electrode discharge, hydrogen-oxygen flame, graphite heating and other fusion splicing methods.

[0141] Preferably, the tapered end can be cut using a fiber cleaver.

[0142] In order to match the bunching region, the multi-core doped active optical fiber includes multiple different doped parts, that is, when the bunching region includes m parts, the multi-core doped active optical fiber includes m doped parts; for example, when the bunching region includes 4 parts, namely the first part of the bunching region, the second part of the bunching region, the third part of the bunching region, and the fourth part of the bunching region, the multi-core doped active optical fiber also includes 4 doped parts; when the bunching region includes 3 parts, namely the first part of the bunching region, the second part of the bunching region, and the third part of the bunching region, the multi-core doped active optical fiber also includes 3 doped parts.

[0143] Figure 4 For a specific embodiment, its corresponding Figure 2 An embodiment of a cluster area.

[0144] Figure 4 In a corresponding embodiment, the cluster area includes three parts, namely, the first cluster area part, the second cluster area part, and the third cluster area part.

[0145] A multi-core doped active fiber includes multiple rare earth ion-doped regions, preferably at least two. Preferably, it has an innermost central rare earth ion-doped region, while the outer rare earth ion-doped regions can be annular. For better symmetry and fiber mode matching, the innermost rare earth ion-doped region is a basic circular region, while the other rare earth ion-doped regions, i.e., the outer rare earth ion-doped regions, are annular. Preferably, it includes at least one central doped ion region and one annular rare earth ion-doped region. In other words, the multi-core in a multi-core doped active fiber refers to amplification regions having at least two rare earth ion-doped regions. Preferably, the multi-core doped active fiber includes three rare earth ion-doped regions, preferably one central rare earth ion-doped region and two annular rare earth ion-doped regions. Compared to multiple discrete circular cores, the stacked annular regions significantly improve the spatial efficiency of laser pumping and increase the laser output energy. This approach offers significant economic advantages in the field of high-power laser output, facilitates heat dissipation, and reduces the occurrence of nonlinear effects.

[0146] Specific reference Figure 4 For explanation. Preferably, the multi-core doped active optical fiber can be mainly composed of three parts 1, 2, and 3 from a cross-sectional view. The third region 1 is a region doped with rare earth thulium ions, preferably a basically annular (ring-shaped) region, the second region 2 is a region co-doped with rare earth erbium and ytterbium ions, preferably a basically annular (ring-shaped) region, and the first region (including 3 and 6) is a region doped with ytterbium ions, preferably a basically circular region. The inner diameter of the third region 1 is 362.5 μm, and the outer diameter of the third region 1 is 487.5 μm. The inner diameter of the second region 2 is 212.5 μm, and the outer diameter of the second region 2 is 337.5 μm.

[0147] When all light wavelengths are to be output in the form of annular light, preferably, the first region includes a central quartz region 6 located in the center and not doped with rare earth ions, and an outer first doped region 3 in the form of annular light. In this case, the optical fiber located at the center of the first part of the cluster region is preferably a pump fiber, which facilitates omnidirectional pumping of the first doped region with a pump laser (because no excitation light is emitted from the center, if the center is a signal fiber, it will not have any beneficial effect and will reduce the excitation efficiency), thereby improving the excitation efficiency and reducing energy loss.

[0148] In this case, the inner diameter of the first doped region 3 is 62.5 μm, and the outer diameter of the first doped region 3 is 187.5 μm. Portions 4, 5, 6, and 7 are composed of quartz. Of course, if the optical field cross-section of the laser wavelength at the center of the final output laser is required to be circular, the first region may not include the central region 6 undoped with rare earth ions, and may only include the first doped region 3, which is circular.

[0149] The first region is a substantially circular region, doped with a first rare earth ion, and configured to amplify a first signal light. The second region surrounds the first region, the second region being substantially annular (ring-shaped) and doped with a second rare earth ion, and configured to amplify a second signal light. The third region surrounds the second region, the second region being substantially annular (ring-shaped) and doped with a third rare earth ion, and configured to amplify a third signal light. The multi-core doped active optical fiber includes a central rare earth ion-doped region and one or more outer annular (ring-shaped) rare earth ion-doped regions. Preferably, a quartz layer is disposed between any two rare earth ion-doped regions to isolate the laser. Preferably, a quartz layer is disposed outside the outermost rare earth ion-doped region to prevent laser leakage and human injury.

[0150] A quartz layer 7 is provided between the first region and the second region 2 . The thickness of the quartz layer is preferably the inner diameter of the second region minus the outer diameter of the first region 3 , ie, the thickness on one side is 12.5 μm and the thickness on both sides is 25 μm in total.

[0151] A quartz layer 5 is provided between the second region 2 and the third region 1 . The thickness of the quartz layer is preferably the inner diameter of the third region 1 minus the outer diameter of the second region 2 , with a thickness of 12.5 μm on one side and a total thickness of 25 μm on both sides.

[0152] A quartz layer 4 is provided on the outside of the third region 1 . The thickness of the quartz layer is preferably 12.5 μm on one side and 25 μm in total on both sides.

[0153] Preferably, a quartz core region (ie, central quartz region) 6 is provided inside the first region. The quartz core region 6 is substantially a circular region, and the diameter of the quartz core region 6 is substantially the inner diameter of the first doped region 3 .

[0154] According to the design, the refractive index of the quartz layer and the quartz core is lower than that of the first region, the refractive index of the quartz layer is lower than that of the second region, and the refractive index of the quartz layer is lower than that of the third region. Preferably, the refractive index of regions 1, 2, and 3 doped with rare earth ions is the same and greater than the refractive index of the quartz material in regions 4, 5, 6, and 7. Therefore, the effective numerical aperture of region 1 is 0.3; the effective numerical aperture of region 2 is 0.3; and the effective numerical aperture of region 3 is 0.3. Therefore, regions 1, 2, and 3 all have excellent functions of limiting light transmission, and can basically realize separate transmission of laser light in each region without basically interfering with each other. Similar to the core of an optical fiber, the optical fiber can be considered as a ring-shaped multi-core structure optical fiber. As shown in the attached figure Figure 2 、 4As shown, the first part c of the clustering area, the second part b of the clustering area, and the third part a of the clustering area respectively correspond to the first region, the second region 2, and the third region 1 of the multi-core doped active optical fiber; that is, the first part c of the clustering area corresponds to the first region through the clustering tapered area, the second part b of the clustering area corresponds to the second region 2 through the clustering tapered area, and the third part a of the clustering area corresponds to the third region 3 through the clustering tapered area.

[0155] Points d, e, and f in the clustering region correspond to regions 4, 5, and 7 of the multi-core doped active fiber, respectively. Specifically, the low-refractive-index silica glass tube between the first and second portions of the clustering region passes through the clustering tapered region and corresponds to the silica layer between the first and second portions of the multi-core doped active fiber; the low-refractive-index silica glass tube between the second and third portions of the clustering region passes through the clustering tapered region and corresponds to the silica layer between the second and third portions of the multi-core doped active fiber; and the low-refractive-index silica glass tube outside the third portion of the clustering region passes through the clustering tapered region and corresponds to the silica layer outside the third portion of the multi-core doped active fiber.

[0156] Preferably, in the multi-wavelength amplified ring laser output by the multi-core doped active optical fiber, the first signal light L1 and the first pump light P1 and the output laser part corresponding to the first region are the first output light part Q1; the second signal light L2 and the second pump light P2 and the output laser part corresponding to the second region are the second output light part Q2; the third signal light L3 and the third pump light P3 and the output laser part corresponding to the third region are the third output light part Q3; when the part of the beam area exceeds 3 parts, the nth signal light Ln and the nth pump light Pn and the output laser part corresponding to the nth region are the nth output light part Qn (n>3, which is a positive integer).

[0157] Regarding the amplification of the multi-core fiber laser, according to the above information, since each region 1, 2, and 3 is doped with different rare earth ions, the third region 1 is doped with thulium ions, the second region 2 is co-doped with erbium and ytterbium ions, and the first region is doped with ytterbium ions. According to the design of the fiber structure, each region has a numerical aperture. At the same time, each thulium-doped, erbium-ytterbium, and ytterbium laser that needs to be amplified and the corresponding pump laser are respectively restricted to be transmitted in regions 1, 2, and 3. Therefore, the amplification of the above three lasers is spatially separated. Therefore, the amplification size of each of the above lasers can be controlled by controlling the injection size of the signal light and the pump light in regions 1, 2, and 3. This amplification structure is essentially a Mopa amplification structure. Therefore, it has the characteristic that the amplified output laser depends on the beam quality of the signal laser. In this patent, thulium, erbium, and ytterbium single-mode lasers are used as signal light, so that high beam quality and high output power output can be obtained.

[0158] Furthermore, the signal and pump fibers in regions a, b, and c have the same outer diameter of 125 μm. Therefore, while maintaining the same total number of signal and pump fibers in each region, the ratio of signal to pump fibers can be adjusted based on application requirements, either increasing the number of signal fibers and decreasing the number of pump fibers, or decreasing the number of signal fibers and increasing the number of pump fibers. This method allows for flexible control of the injection ratio of signal and pump light, ultimately enabling the individual control of the output of each amplified laser.

[0159] Preferably, sometimes due to slight differences in the taper conditions of the various optical fibers in the clustering tapered area, the energy transmission conditions of the various pump fibers and signal fibers are different, which causes the light field of the annular light spot to be slightly uneven. In order to solve this problem, the inventors have thought of making the energy and power of the pump lasers corresponding to the various pump fibers in the various parts of the clustering area independently adjustable. For example, the first part of the clustering area includes multiple pump fibers, and the energy of the pump laser in each pump fiber is independently adjustable. A detection device for the annular light spot is set at the output end of the multi-core rare earth ion doped gain fiber. A device (for example, a CCD camera including an attenuator) independently adjusts the pump laser power of each pump fiber according to the light field uniformity of the annular light spot detected by the annular light spot detection device. When the light field uniformity of the annular light spot obtained by the annular light spot detection device reaches a predetermined value, the pump laser power values ​​in the respective pump fibers and / or the pump laser power ratios of the respective pump fibers at that time are recorded. Then, the pump laser power values ​​in the respective pump fibers and / or the pump laser power ratios of the respective pump fibers are used to obtain a uniform first output laser portion.

[0160] Preferably, the second part of the beam-forming region may include a plurality of pump fibers, the energy of the pump laser in each pump fiber is independently adjustable, a ring-shaped light spot detection device (for example, a CCD camera including an attenuation plate) is provided at the output end of the multi-core rare-earth ion-doped gain fiber, and the pump laser power of each pump fiber is independently adjusted according to the light field uniformity of the ring-shaped light spot detected by the ring-shaped light spot detection device. When the light field uniformity of the ring-shaped light spot obtained by the ring-shaped light spot detection device reaches a predetermined value, the pump laser power value in each pump fiber and / or the pump laser power ratio of each pump fiber at this time is recorded, and then the pump laser power value in each pump fiber and / or the pump laser power ratio of each pump fiber are used to obtain a uniform second output laser portion.

[0161] Preferably, the third part of the beam-forming region may include a plurality of pump fibers, the energy of the pump laser in each pump fiber is independently adjustable, a ring-shaped light spot detection device (for example, a CCD camera including an attenuator) is provided at the output end of the multi-core rare-earth ion-doped gain fiber, and the pump laser power of each pump fiber is independently adjusted according to the light field uniformity of the ring-shaped light spot detected by the ring-shaped light spot detection device. When the light field uniformity of the ring-shaped light spot obtained by the ring-shaped light spot detection device reaches a predetermined value, the pump laser power value in each pump fiber and / or the pump laser power ratio of each pump fiber at this time is recorded, and then the pump laser power value in each pump fiber and / or the pump laser power ratio of each pump fiber are used to obtain a uniform third output laser portion.

[0162] Preferably, the nth part of the clustering region may include multiple pump fibers, the energy of the pump laser in each pump fiber is independently adjustable, and a ring-shaped light spot detection device (for example, a CCD camera including an attenuation plate) is provided at the output end of the multi-core rare earth ion-doped gain fiber. The pump laser power of each pump fiber is independently adjusted according to the light field uniformity of the ring-shaped light spot detected by the ring-shaped light spot detection device. When the light field uniformity of the ring-shaped light spot obtained by the ring-shaped light spot detection device reaches a predetermined value, the pump laser power value in each pump fiber and / or the pump laser power ratio of each pump fiber at this time is recorded. Then, the pump laser power value in each pump fiber and / or the pump laser power ratio of each pump fiber are used to obtain a uniform nth output laser part (n>3, which is a positive integer).

[0163] In view of the structural design of the multi-core rare earth ion-doped gain fiber, it can realize the output of composite wavelength laser ring spot laser.

[0164] Through optical fiber structure design, the number of core regions of a multi-core doped optical fiber can be increased to increase the types of doped rare earth ions, such as neodymium, holmium, samarium, praseodymium, etc.; for the selection of signal light wavelength in this patent, the wavelength selection can be extended to the wavelength covered by the emission spectrum of each doped rare earth ion.

[0165] The advantage of the present application also lies in the structural design of the bundled fiber area combiner that achieves efficient coupling with multi-core doped optical fibers.

[0166] In addition to achieving the output of high-power composite wavelength lasers, this application also enables the output of composite wavelength annular spot lasers. At the same time, the individual wavelength components of the composite wavelength laser can be independently controlled. Preferably, the signal light module in the signal light and pump light module can independently control the intensity and emission of the signal lasers at each wavelength. The pump light module in the signal light and pump light module can independently control the intensity and emission of the pump lasers at each wavelength.

[0167] Since the pump laser is multimode, there will be mode mismatch when using a single-mode signal fiber, resulting in low utilization efficiency of the pump light, wasting light energy, and reducing efficiency. To solve this problem, the inventor replaced the signal fiber with a few-mode laser fiber to solve the mode mismatch problem in the above-mentioned pumping process. At the same time, the core diameter of the few-mode signal fiber and the core diameter of the multimode pump fiber can be increased. Preferably, the signal fiber is selected as a few-mode fiber with a core diameter greater than 15μm and a cladding diameter greater than 150μm, and preferably, the pump fiber is selected as a multimode fiber with a core diameter greater than 133μm and a cladding diameter greater than 153 (or more preferably, the signal fiber is selected as a few-mode fiber with a core diameter greater than 18μm and a cladding diameter greater than 180μm, and preferably, the pump fiber is selected as a multimode fiber with a core diameter greater than 150μm and a cladding diameter greater than 180); so that the multimode pump fiber can transmit more energy and reduce the energy density per unit cross section to reduce heat generation and nonlinear effects. At the same time, due to the limitation of the taper ratio, the core diameter and cross-sectional area of ​​each part of the multi-core rare earth ion-doped gain fiber can be correspondingly increased to output higher-energy laser light and reduce the energy density per unit cross-section, thereby reducing nonlinear effects. For example, this may include the following embodiments.

[0168] By designing the clustering region and multi-core doped fiber structure, the pump fiber and signal fiber in the clustering region are replaced with fibers with the same cladding diameter but larger core diameters and higher numerical apertures. For example, the pump fiber can be replaced with a 200 / 220 / 0.22 multimode fiber, and the signal fiber can be replaced with a 20 / 200 few-mode laser fiber. This reduces the pump light brightness requirement of the amplifier structure, thereby reducing its manufacturing cost.

[0169] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are intended solely to illustrate the principles of the present invention and are not to be construed in any way as limiting the scope of protection of the present invention. Based on the explanations herein, those skilled in the art will readily conceive of other specific embodiments of the present invention without inventive effort, and such embodiments will fall within the scope of protection of the present invention.

Claims

1. A multi-core rare earth ion-doped multi-wavelength power-tunable fiber laser, comprising a signal light and pump light module, a signal light and pump light output fiber bundling region, a bundling tapered region, and a multi-core doped active fiber; the signal light and pump light module is used to output the signal laser to be amplified and the pump laser required for signal light amplification; the signal light and pump light output fiber bundling region comprises a signal fiber and a pump fiber, which bundles the signal fiber and the pump fiber; the signal fiber is used to transmit the signal laser to be amplified, and the pump fiber is used to transmit the pump laser required for signal light amplification; the bundling tapered region is obtained by tapering the signal light and pump light output fiber bundling region; the bundling tapered region is connected to the multi-core doped active fiber, characterized in that: The multi-core doped active optical fiber includes at least two rare earth ion doped regions, and the signal light and pump light output fiber bundling area includes a first bundling area part and a second bundling area part. The first bundling area part includes a signal optical fiber and a pump optical fiber, and the second bundling area part includes a signal optical fiber and a pump optical fiber. The first bundling area part is a circular area, and the second bundling area part surrounds the first bundling area part. The second bundling area part is an annular area. The first bundling area part includes a first signal optical fiber and a first pump optical fiber. The first signal optical fiber is used to transmit a first signal laser L1, and the first pump optical fiber is used to transmit a first pump laser P1. The second bundling area part includes a second signal optical fiber and a second pump optical fiber. The second signal optical fiber is used to transmit a second signal laser L2, and the second pump optical fiber is used to transmit a second pump laser P2. The first rare earth ion material absorbs the first pump laser P1 and inverts the particle number, and emits the amplified first signal laser L1. The second rare earth ion material absorbs the second pump laser P2 and inverts the particle number, and emits the amplified second signal laser L2.

2. A multi-core rare earth ion-doped multi-wavelength power-tunable fiber laser according to claim 1, further comprising a third portion of a beam-coating region, the third portion of the beam-coating region comprising a signal fiber and a pump fiber, the third portion of the beam-coating region being an annular region surrounding the second portion of the beam-coating region, the third portion of the beam-coating region comprising a third signal fiber and a third pump fiber, the third signal fiber being configured to transmit a third signal laser L3, and the third pump fiber being configured to transmit a third pump laser P3; the third rare earth ion material absorbs the third pump laser P3 and causes a population inversion, thereby emitting amplified third signal laser L3.

3. According to claim 2, a multi-core rare earth ion-doped multi-wavelength power tunable fiber laser, wherein a quartz low-refractive-index glass tube is disposed between the first and second portions of the beam-forming region; a quartz low-refractive-index glass tube is disposed between the second and third portions of the beam-forming region; and the outermost portion of the beam-forming region of the signal light and pump light output fiber comprises a quartz low-refractive-index glass tube, the refractive index of the quartz low-refractive-index glass tube being lower than the refractive index of the core of the pump fiber.

4. According to claim 2, a multi-core rare earth ion-doped multi-wavelength power tunable fiber laser, the multi-core doped active fiber comprising a first region, a second region, and a third region, wherein the first region is doped with a first rare earth ion for amplifying a first signal light; the second region surrounds the first region, the second region is an annular region, and is doped with a second rare earth ion for amplifying a second signal light; and the third region surrounds the second region, the third region is an annular region, and is doped with a third rare earth ion for amplifying a third signal light.

5. A multi-core rare earth ion doped multi-wavelength power tunable fiber laser according to claim 3, wherein the multi-core doped active fiber comprises a first region, a second region, and a third region, wherein the first region is doped with a first rare earth ion; The second region is a ring-shaped region doped with a second rare earth ion; The third region is an annular region, doped with a third rare earth ion, and a quartz layer is arranged between the first region and the second region; a quartz layer is arranged between the second region and the third region; a quartz layer is arranged outside the third region, and the refractive index of the quartz layer is lower than the refractive index of the first region, the refractive index of the quartz layer is lower than the refractive index of the second region, and the refractive index of the quartz layer is lower than the refractive index of the third region.

6. According to claim 4, in a multi-core rare earth ion-doped multi-wavelength power tunable fiber laser, the wavelength of the first signal laser L1 is smaller than the wavelength of the second signal laser L2 located in the second portion of the beam-focusing region; and the wavelength of the second signal laser L2 located in the second portion of the beam-focusing region is smaller than the wavelength of the third signal laser L3 located in the third portion of the beam-focusing region.

7. According to claim 2, a multi-core rare earth ion-doped multi-wavelength power-tunable fiber laser, the signal fiber in the first part of the beam region is a passively matched single-mode fiber capable of transmitting laser light emitted by ytterbium ions, and the pump fiber in the first part of the beam region is a coupled-out fiber of a pump source that outputs laser light that can pump ytterbium ion-doped materials; the signal fiber in the second part of the beam region is a passively matched single-mode fiber capable of transmitting laser light that can be emitted by erbium ions, and the pump fiber in the second part of the beam region is a coupled-out fiber of a pump source that outputs laser light that can pump erbium-ytterbium ion co-doped materials; the signal fiber in the third part of the beam region is a passively matched single-mode fiber capable of transmitting laser light that can be emitted by thulium ions, and the pump fiber in the third part of the beam region is a coupled-out fiber of a pump source that outputs laser light that can pump thulium ion-doped materials; and the pump source is a laser diode pump source.

8. According to claim 1, a multi-core rare earth ion doped multi-wavelength power tunable fiber laser, wherein the taper length of the cluster taper region satisfies the insulating taper condition: the diffraction angle within the fiber ≥ the fiber taper angle; after the fiber is tapered, the taper end is cut and then fused to the multi-core doped active fiber.

9. A multi-core rare earth ion-doped multi-wavelength power tunable fiber laser according to claim 1, wherein the signal fiber is a single-mode fiber and the pump fiber is a multi-mode fiber; or, the signal fiber is a few-mode laser fiber and the pump fiber core diameter is greater than 133 μm.

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