CN115425507A - Distributed gain high-power all-fiber laser resonant cavity - Google Patents

Abstract

The invention relates to a distributed gain high-power all-fiber laser resonant cavity. The adopted technical scheme is as follows: the system comprises a high-power all-fiber laser resonant cavity array and a multi-core fiber beam combiner which are connected; the laser resonant cavity arrays are the same, and the output optical fibers of the shared multi-core optical fiber beam combiner are used as output end resonant cavity mirrors; the input end of the multi-core optical fiber combiner is separated into a plurality of input tail fibers corresponding to fiber cores of output optical fibers of the multi-core optical fiber combiner, and the input tail of the multi-core optical fiber combiner and the laser output optical fibers of the laser resonant cavity array have matched fiber core mode field parameters; and the output optical fiber of the multi-core beam combiner is provided with a laser feedback element. The invention can greatly improve the pumping light power bearing capacity of the high-power all-fiber laser resonant cavity and effectively reduce the heat management difficulty of the high-power all-fiber laser, thereby greatly improving the output power level of the high-power all-fiber laser under the condition of the development process level of the existing high-power laser fiber material and device.

Description

A high-power all-fiber laser resonator with distributed gain

technical field

The invention relates to the field of laser technology, in particular to a high-power all-fiber laser resonator with distributed gain.

Background technique

High-power all-fiber lasers have many advantages, such as good beam quality, high electro-optic efficiency, free from debugging and maintenance, flexible laser output, small size, light weight, long service life, etc., and have gradually replaced original lasers in industrial processing, national defense and military applications. There are chemical, gas and general solid-state lasers for a wide range of applications. In recent years, the rapid development of high-power laser processing and other application technologies, such as: laser cutting, welding and other laser industrial processing speeds have been continuously improved, and there is a more urgent demand for high-power all-fiber lasers with higher power levels.

High-power all-fiber lasers use core fiber devices such as large-mode field gain fibers and fiber gratings, high-power fiber-coupled semiconductor lasers, and pump couplers. Generally, high-power all-fiber laser resonators are used to generate kilowatt-level high-beam quality fiber lasers, and then The amplified output of fiber laser power is realized through a high-power all-fiber laser resonator. In order to increase the output power level, it is necessary to increase the pump power, which makes the core fiber device of the high-power all-fiber laser concentratedly bear the heat generated by the higher power pump light, laser and laser gain. Therefore, the improvement of the existing integration technology level directly depends on the performance of the core fiber device of the high-power all-fiber laser. However, because the development process level of the core optical fiber device is difficult to meet the demand for a substantial increase in the output power level, the bottleneck of the integration technology appears. In recent years, the output power level of high-power all-fiber lasers has not increased significantly.

Contents of the invention

The purpose of the present invention is to provide a high-power all-fiber laser resonator with distributed gain, so as to solve the bottleneck problem faced by the existing high-power all-fiber laser in increasing the output power level.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A high-power all-fiber laser resonator with distributed gain, including a connected high-power all-fiber laser resonator array and a multi-core fiber combiner;

The high-power all-fiber laser resonator array has exactly the same device, integrated technical parameters and process, and it shares the output fiber of the multi-core fiber combiner as the output resonator mirror;

The input end of the multi-core fiber combiner is separated into a plurality of input pigtails corresponding to the core of the output fiber, the input pigtail of the multi-core fiber combiner and the laser output fiber of the high-power all-fiber laser resonator array With matching core mode field parameters;

The output fiber of the multi-core beam combiner is provided with a laser feedback element.

Further, the laser feedback element is to install a laser collimator mirror and a partially reflective plane mirror at the output end of the output fiber of the multi-core beam combiner.

Further, the laser feedback element is a fiber grating written on the output fiber core of the multi-core beam combiner.

Further, the output fiber of the multi-core fiber combiner is a multi-core fiber without doped gain ions, and its core diameter is expressed as dcore, which satisfies dcore≤30 μm, and the core spacing is expressed as Dcore, adjacent cores The gap between them (Dcore-dcore)≤20μm.

Compared with prior art, the advantage of the present invention is:

1) The present invention uses a multi-core fiber combiner to realize the array distributed gain of a high-power all-fiber laser resonator, effectively reducing the number of core fibers such as large-mode-field fiber gratings, large-mode-field gain fibers, and high-power fiber pump couplers. The risk of laser damage to the device can be obtained by using a high-power all-fiber laser resonator to obtain a high-power fiber laser with high beam quality.

2) The present invention uses an array-distributed high-power all-fiber laser resonator to realize the dispersed distribution of high-power pump light, and greatly improves the pump light power carrying capacity of the high-power all-fiber laser resonator.

3) When the high-power all-fiber laser resonator based on the present invention is working, the heat generated by laser gain is dispersed and distributed in the high-power all-fiber laser resonator array, which effectively reduces the difficulty of thermal management of the high-power all-fiber laser.

4) By optimizing the integration parameters and process of the multi-core beam combiner and the high-power all-fiber laser resonator array, it is expected that under the conditions of the existing high-power laser fiber material and device development process level, based on the present invention, close Diffraction-limited tens of kilowatts of fiber laser output.

5) Compared with the MOPA structure of high-power all-fiber laser resonator + high-power all-fiber laser amplifier commonly used in existing high-power all-fiber lasers, the high-power all-fiber laser based on the present invention only includes one level of high-power all-fiber laser Resonant cavity, when integrated with laser application systems such as laser industrial processing, the control difficulty is reduced, and the system compatibility is higher.

6) The two structures selected for the laser feedback element can be used in the resonant cavity mirror at the output end of the present invention to obtain a higher output laser power carrying capacity than the output cavity mirror of the existing high-power all-fiber laser resonant cavity. Among them, the laser feedback element composed of a laser collimator and a partially reflective plane mirror is separated from the output fiber of the multi-core beam combiner, which makes the production, installation, maintenance, replacement and upgrade simple and easy to operate; directly in the multi-core beam combiner The laser feedback element formed by writing fiber gratings on the output fiber of the beamer, forms an integrated high-power all-fiber laser resonator together with the high-power all-fiber laser resonator array and the multi-core fiber combiner, and obtains high-power flexible output Fiber laser, easy to integrate with laser processing and other equipment.

Description of drawings

Fig. 1 is the structure schematic diagram of the present invention.

Reference signs: 1-high-power all-fiber laser resonator array, 2-multi-core fiber combiner, 3-laser output fiber of high-power all-fiber laser resonator array, 4-input tail of multi-core fiber combiner Fiber, the output fiber of the 5-multicore beam combiner.

detailed description

The technical solutions in this embodiment will be clearly and completely described below in conjunction with the embodiments and accompanying drawings.

Embodiment: Referring to FIG. 1 , a high-power all-fiber laser resonator with distributed gain provided by the present invention includes a high-power all-fiber laser resonator array 1 and a multi-core fiber combiner 2 . The output fiber of the described multi-core fiber combiner 2 is a multi-core fiber of non-doped gain ions, its core diameter dcore≤30 μm, and the core spacing is expressed as Dcore, and the gap between adjacent cores (Dcore -dcore)≤20μm. The output fiber 5 of the multi-core beam combiner is equipped with a laser feedback element with a reflectivity of R to the laser wavelength, and the laser feedback element can be a laser collimator and a partially reflective plane mirror installed at the end of the output fiber 5, Or directly write the fiber grating on the 5th core of the output fiber of the multi-core beam combiner. The reflectivity of the laser feedback element in the two structures is R≤90%. Both structures can make the output fiber have both laser output and feedback functions. . The input end of the multi-core optical fiber combiner 2 is separated into a plurality of input pigtails 4 corresponding to the cores of the output optical fibers 5 of the multi-core optical fiber combiner, and the input pigtails 4 resonate with the high-power all-fiber laser The laser output fibers 3 of the cavity array have the same core mode field parameters. The all-fiber laser resonator array 1 is identical, has the same optical fiber devices, integrated technical parameters and processes, and the high-inverse resonator mirror and the laser feedback element of the output fiber 5 of the multi-core fiber combiner have the same laser reflection In the center of the spectrum, the output power of the array unit FL1-N can be independently adjusted by adjusting the pump light power by sharing the output fiber 5 of the multi-core fiber combiner as the output resonant cavity mirror.

Working principle of the present invention: referring to Fig. 1, the multi-channel fiber laser produced by the high-power all-fiber laser resonator array 1 is coupled into the output fiber 5 through the input pigtail 4 of the multi-core fiber combiner corresponding to the output fiber 3, Due to the strong coupling of multiple core optical fields of the output fiber 5, they are recombined and form a stable transmission fiber laser. The laser feedback element installed in the output fiber 5 outputs a part of the fiber laser transmitted therein, and the other part is reflected and then transmitted in reverse and injected into the corresponding high-power all-fiber laser resonator array 1 after beam splitting by the multi-core fiber combiner 2, Fiber laser resonance is formed.

During preparation, one end of the output fiber is bundled, fused and tapered and cut, and then fused with multiple cores of the multi-core fiber to form a multi-core fiber combiner; or the multi-core fiber is prefabricated when drawing the multi-core fiber One end of the rod is separated according to the distribution of the fiber cores, and the multi-core fiber combiner with one end of the tail fiber separated can be integrally drawn by drawing the optical fiber.

In this embodiment, the all-fiber laser resonator array 1 has better coherence; the multi-core optical fiber has the same-phase supermode close to the diffraction limit. Therefore, the high-power all-fiber laser cavity array 1 can obtain a high-power, high-beam-quality all-fiber laser beam through the output fiber 5 of the multi-core fiber. For example, the multi-core optical fiber 5 has 37 cores, and the all-fiber laser resonator array unit FL1-N can generate a fiber laser with a power of 1000 watts, then the high-power all-fiber laser resonator array 1 passes through the multi-core fiber combiner 2 A fiber laser with high beam quality of about 37,000 watts can be obtained.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the present invention, some improvements and replacements can also be made, these improvements and replacements It should also be regarded as the protection scope of the present invention.

Claims (4)

1. A high-power all-fiber laser resonator of distributed gain, characterized in that: comprise a connected high-power all-fiber laser resonator array (1) and a multi-core fiber combiner (2); The high-power all-fiber laser resonator array (1) is identical, and the output fiber (5) of the shared multi-core fiber combiner is used as the output resonator mirror; The input end of the multi-core fiber combiner (2) is separated into a plurality of input pigtails (4) corresponding to the cores of the output optical fibers, and the input pigtails (4) of the multi-core fiber combiner are connected to the high-power full The laser output fiber (3) of the fiber laser resonator array has matched core mode field parameters; A laser feedback element is arranged on the output optical fiber (5) of the multi-core beam combiner. 2. the high-power all-fiber laser resonator of distributed gain as claimed in claim 1 is characterized in that: described laser feedback element is installed at the output end of the output optical fiber (5) of multi-core beam combiner Advanced laser collimator and partially reflective plane mirror, reflectivity R≤90%. 3. the high-power all-fiber laser resonator of distributed gain as claimed in claim 1 is characterized in that: described laser feedback element is the optical fiber written in the output optical fiber (5) fiber core of multi-core beam combiner Grating, reflectivity R≤90%. 4. the high-power all-fiber laser resonator of distributed gain as claimed in claim 2 or 3, is characterized in that: the output optical fiber (4) of described multi-core optical fiber beam combiner is the multiple of non-doped gain ion Core fiber, the core diameter is expressed as dcore, satisfying dcore≤30μm, the distance between cores is expressed as Dcore, and the gap between adjacent cores (Dcore-dcore)≤20μm.

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