CN-121983838-A - Laser synthesis system and method based on multi-core optical fiber

CN121983838ACN 121983838 ACN121983838 ACN 121983838ACN-121983838-A

Abstract

The invention discloses a laser synthesis system based on a multi-core fiber, which comprises a laser device, a multi-core fiber, a beam regulation device and a reflection grating, wherein the laser device is used for providing multiple paths of lasers with different wavelengths, the multi-core fiber is provided with N fiber cores, each fiber core is a hollow fiber core, the input end of each fiber core is respectively connected with the laser device, the output section of each fiber core is a straight line, the output section of each fiber core is provided with an emergent end face, the emergent end faces of the fiber cores are arranged according to a one-dimensional array or a two-dimensional array, the beam regulation device is arranged between the output end of the multi-core fiber and the reflection grating, and the reflection grating is used for reflecting the multiple paths of lasers output by the beam regulation device and enabling the reflected multiple paths of lasers to be on the same straight line, so that the multiple paths of lasers gathered on the reflection grating are synthesized into one path of synthesized laser. The invention can simplify the traditional synthetic optical path design, obviously reduce the size and weight of the synthesizing device and further expand the application range of the high-energy laser.

Inventors

LI QIANG
Wei ankang
LEI MIN
LV LIANG
HU JINMENG
JIANG YONGLIANG
LIU HOUKANG
ZHENG BAOLUO
WU PENG
SONG RUI

Assignees

湖北航天飞行器研究所

Dates

Publication Date: 20260505
Application Date: 20251230

Claims (10)

1. The utility model provides a laser synthesis system based on multicore optic fibre, its characterized in that includes laser device, multicore optic fibre, light beam regulation and control device and reflection grating to: The laser device is used for providing multiple paths of lasers with different wavelengths; the multi-core optical fiber is provided with N fiber cores, each fiber core is a hollow fiber core, the input end of each fiber core is respectively connected with the laser device so as to respectively inject one path of laser into each fiber core, the output sections of each fiber core are straight lines and are parallel to each other, the output section of each fiber core is provided with an emergent end face, and the emergent end faces of the fiber cores are arranged in a one-dimensional array or a two-dimensional array, wherein N is more than or equal to 3; the beam regulating device is arranged between the output end of the multi-core optical fiber and the reflection grating and is used for focusing the multipath laser output by the output end of the multi-core optical fiber onto the reflection grating; the reflection grating is used for reflecting the multiple paths of laser beams output by the light beam regulating device and enabling the reflected multiple paths of laser beams to be on the same straight line, so that the multiple paths of laser beams collected on the reflection grating are combined into one path of combined laser beam.
2. The multi-core fiber-based laser synthesis system of claim 1, wherein the laser device comprises a plurality of single wavelength fiber lasers; or the laser device adopts a multi-wavelength fiber laser.
3. The laser synthesis system based on the multi-core optical fiber according to claim 1, wherein the multi-core optical fiber is an anti-resonance hollow optical fiber, a quartz end cap is welded on the outgoing end face of the multi-core optical fiber, and an anti-reflection film is arranged on the output face of the quartz end cap to reduce the end face power density and prevent dust from entering the hollow fiber core.
4. A laser synthesis system based on multicore fibers according to claim 1, wherein the exit end faces of the cores are arranged in a one-dimensional array; The light beam regulating device is a focusing lens; the emergent end faces of all fiber cores are coplanar with the object space focal plane of the focusing lens; each laser incident on the grating has an intersection point with the reflection grating, and all the intersection points are on the image space focal plane of the focusing lens.
5. The system of claim 4, wherein the multicore fiber has an odd number of cores, and the grating constant d of the reflection grating and the wavelength λ n of the laser light in each core except the middle-most core are determined according to the total number N of cores of the multicore fiber, the center distance d y of the exit end faces of any two adjacent cores, the wavelength λ 0 of the laser light in the middle-most core, and the focal length f 1 of the focusing lens, specifically as follows: 1) Taking the center line of the output section of the middle fiber core as the X axis of a Cartesian coordinate system, taking the center of the emergent end face of the middle fiber core as the coordinate origin O of the Cartesian coordinate system, taking the straight line perpendicular to the X axis as the Y axis, and taking the center lines of the output sections of all fiber cores as the X axis, the Y axis coordinate values of the centers of the emergent end faces of the nth fiber core are as follows: y core (n)=[n−(N+1)/2]×d y , wherein n=1, 2., N-1, N; Wherein d y is micron, and the 1 st fiber core and the N th fiber core are two fiber cores from head to tail; 2) Grating constant d=λ 0 /2 sin γ; Wherein the wavelength lambda 0 of the laser is in nm, and gamma is the included angle between the central line of the output section of the fiber core in the middle and the normal line of the reflection grating; 3) When the laser coming out of the nth fiber core is incident on the reflection grating, an included angle gamma 1 (n) between the laser and the normal line of the reflection grating is as follows: γ 1 (n)=γ+arctan[y core (n)/1000f 1 ]; Wherein f 1 is in millimeters; 4) Determining the wavelength λ (j) of the laser light in the jth core: λ(j)=d×[sinγ 1 (j)+sinγ]: where j=1, 2..n-1, N and j+ (n+1)/2.
6. The multi-core fiber based laser synthesis system of claim 5, wherein d y =50μm∼300μm,f 1 =40mm∼100mm,λ 0 = 900nm 2 1100nm, γ = 20 ° 30 °.
7. A laser synthesis system according to claim 1, wherein the emitting end faces are arranged in a two-dimensional array, each row having P emitting end faces, each column having P emitting end faces; the laser device includes: the seed source is used for providing a laser signal with single frequency and narrow linewidth; the beam splitting mechanism is connected with the seed source and is used for equally splitting the laser signal into multiple paths of sub-beams so as to ensure that the initial frequency and the initial polarization state of the P paths of lasers in each row are consistent; The phase control unit is used for carrying out phase real-time modulation on each sub-beam so as to compensate phase deviation generated by a multi-core optical fiber transmission path and ensure that laser phases output by P fiber cores of each row are synchronous in an interference area; the beam regulating device comprises a positive cylindrical lens, a diffraction optical element and a focusing lens which are sequentially arranged along a laser propagation path, and the positive cylindrical lens, the diffraction optical element and the focusing lens are used for enabling the P paths of laser beams in the same row to realize coherent constructive superposition at the diffraction optical element.
8. The laser synthesis system according to claim 7, wherein the lasers output by the laser device are all linearly polarized light, and the multi-core fiber is a polarization-preserving anti-resonant hollow fiber.
9. The system of claim 7, wherein the diffractive optical element is located between a back focal plane of the positive cylindrical lens and an object focal plane of the focusing lens, and the focal length of the positive cylindrical lens is adjusted so that the light spots of each row of laser on the diffractive optical element are completely overlapped, and the incident angle meets the Bragg diffraction condition of the diffractive optical element, thereby realizing coherent beam combination of the laser.
10. The laser synthesis method of the laser synthesis system based on the multi-core optical fiber is characterized by comprising the following steps of: 1) Providing multiple paths of lasers with different wavelengths by using a laser device; 2) Injecting the multiple paths of lasers into the input ends of N hollow fiber cores of the multi-core fiber respectively, wherein N is more than or equal to 3; 3) After being transmitted through the output sections of the multi-core optical fibers which are parallel to each other, the multi-path laser is emitted from the emitting end surfaces arranged in a one-dimensional array or a two-dimensional array; 4) Focusing multiple paths of laser output by the multi-core optical fiber onto the reflection grating by using a light beam regulating and controlling device arranged between the output end of the multi-core optical fiber and the reflection grating; 5) And reflecting the multiple paths of laser by using the reflection grating, and enabling the reflected multiple paths of laser to be on the same straight line, so that the multiple paths of laser focused on the reflection grating are combined into one path of combined laser output.

Description

Laser synthesis system and method based on multi-core optical fiber Technical Field The invention belongs to the field of spectrum synthesis, and in particular relates to a laser synthesis system and method based on multi-core optical fibers. Background With the wide application of laser technology in the fields of industrial processing, national defense scientific research, precise detection, deep space communication and the like, the market has shown explosive growth on the requirements of laser output power, beam quality and brightness. Currently, single-path fiber lasers face severe physical limit challenges in the process of power boost. Firstly, the nonlinear effects such as stimulated Brillouin scattering, stimulated Raman scattering and the like can severely limit the further improvement of power under high power density, and secondly, the phenomenon of unstable transverse mode and the thermal damage threshold of the material are adopted, so that the single-fiber output power is gradually close to the physical ceiling. In order to break through the power bottleneck of single-path laser, the laser synthesis technology becomes a main flow path for realizing the output of laser with the power of tens of watts or even higher and high brightness. In the existing spectrum synthesis engineering practice, a plurality of discrete single-core fiber light sources are adopted to be matched with a parabolic reflector for collimation, and then the collimated light is incident to the same position on a diffraction grating. However, because it employs discrete fiber optic light sources, each laser requires a separate mechanical adjustment mechanism and collimating lens set. With the increase of the number of the composite paths, the volume of the whole optical system can increase exponentially, and the system is abnormally bulked. More seriously, the end fixing and the space pointing of the multipath discrete optical fibers are extremely sensitive to environmental vibration and temperature fluctuation, mechanical drift is extremely easy to generate, the superposition degree of each sub-beam on the grating is reduced, and the synthesis efficiency and the light beam quality are seriously affected. This discretized layout makes it difficult for the system to maintain long-term reliability in harsh environments. Currently, the mainstream synthesis system mostly adopts solid silica-based optical fibers as transmission media. However, since laser energy is highly concentrated in solid materials, at high power transmission, the extremely high power density inside the fiber can trigger severe nonlinear effects. Even if the power is shared by increasing the number of optical fibers, the phase distortion and energy loss caused by the solid material cannot be fundamentally eliminated. This limits the initial power of the single sub-beam before it enters the combining system, and thus limits the overall combined output brightness and total power. The existing spectrum synthesis scheme is mainly designed for one-dimensional arrangement of sub-beams. When it is desired to achieve laser synthesis on a larger scale (e.g., tens or even hundreds), a simple one-dimensional expansion can result in an oversized optical element or an angular dispersion range that exceeds the high diffraction efficiency bandwidth of the grating. The current state of the art lacks a mature and compact system architecture in terms of how to efficiently collimate and focus a two-dimensional array of light beams, and how to deep organic couple coherent and spectral synthesis on a physical structure. Disclosure of Invention Aiming at the defects or improvement demands of the prior art, the invention provides a laser synthesis system and a laser synthesis method based on a multi-core optical fiber, which can simplify the traditional synthesis light path design, remarkably reduce the size and weight of a synthesis device and further expand the application range of a high-energy laser. In order to achieve the above object, according to one aspect of the present invention, there is provided a laser synthesizing system based on a multi-core optical fiber, comprising a laser device, a multi-core optical fiber, a beam steering device, and a reflection grating, and: The laser device is used for providing multiple paths of lasers with different wavelengths; the multi-core optical fiber is provided with N fiber cores, each fiber core is a hollow fiber core, the input end of each fiber core is respectively connected with the laser device so as to respectively inject one path of laser into each fiber core, the output sections of each fiber core are straight lines and are parallel to each other, the output section of each fiber core is provided with an emergent end face, and the emergent end faces of the fiber cores are arranged in a one-dimensional array or a two-dimensional array, wherein N is more than or equal to 3; the beam regulating device is arranged between the o