Coherence and spectrum composite synthesis device and method of two-dimensional structure

Abstract

The invention belongs to the technical field of laser, and discloses a coherence and spectrum composite synthesis device of a two-dimensional structure, which comprises a laser sub-beam group (1), a coherence synthesis element (2), an optical conversion device (3) and a dielectric film grating (4) which are sequentially arranged along a light path direction, the laser sub-beam group (1) emits m rows * n columns of laser sub-beams to the coherent combination element (2), the laser sub-beams are combined into one row * n columns of output light beams, the output light beams are further converged to the dielectric film grating (4) through the optical conversion device (3), and finally a beam of combined light is output. According to the invention, the laser sub-beams are expanded to the arrangement of a two-dimensional structure, and a mode of coherent spectrum composite synthesis is adopted, so that compared with an existing spectrum synthesis device and method, the number of the laser sub-beams is increased, and the light beam synthesis with higher power and the miniaturization design of the synthesis device can be realized.

Description

Technical Field

[0001] This invention belongs to the field of laser technology and relates to a two-dimensional coherent spectral recombination synthesis device and method. Background Technology

[0002] Spectral synthesis technology is currently the main technical route in the field of high-energy laser synthesis. Its principle is based on the dense arrangement of narrow-linewidth fiber laser sub-beams of different wavelengths in a one-dimensional array, which are incident on the dielectric film grating at different incident angles and exit at the same diffraction angle to achieve common aperture spectral synthesis.

[0003] However, due to limitations in the size of optical components (such as the aperture of the optical beam expander group and the aperture of the multilayer dielectric grating), the number of laser sub-beams participating in spectral synthesis cannot be increased further, making it difficult to further improve the final spectral synthesis output power. In addition, the current narrow linewidth laser sub-beams adopt a one-dimensional array arrangement structure, and the size of optical components such as the beam expander group and the multilayer dielectric grating is also very large, which is not conducive to the miniaturization and weight reduction of the spectral synthesis system. At the same time, the surface shape of larger optical components is prone to deformation due to stress, which is also not conducive to the beam quality of spectral synthesis.

[0004] Therefore, it is necessary to improve the existing spectral synthesis system to expand the number of light sources participating in the synthesis, thereby increasing the output power of the spectral synthesis.

[0005] Patent application (CN 113794100 A) proposes a two-dimensional spectral synthesis device, employing a two-dimensional array arrangement to achieve high-power, miniaturized spectral synthesis through two spectral synthesis processes. Patent application (CN115629483 A) proposes a two-dimensional spectral synthesis method based on the conical diffraction effect, where the wavelengths and arrangement intervals of the laser sub-beams involved in the synthesis are determined by the conical diffraction effect. It can be seen that extending the laser sub-beams from one-dimensional to two-dimensional arrangement is an effective way to achieve high-power, miniaturized spectral synthesis. However, the synthesis of two-dimensional beams, whether through two-stage spectral synthesis or utilizing the conical diffraction principle, requires, in practice, tilting the grating to a specific angle or using relay optical devices to adjust the angle of the sub-beams, and the sub-beam wavelengths need to be adjusted according to the design of the optical system.

[0006] Coherent combining with a common aperture can combine multiple laser sub-beams of the same wavelength into a single beam without requiring additional adjustment of the grating or the angle of the laser sub-beams, making it a simple and effective way to increase laser combining power. A composite combining method based on two-dimensionally arranged laser sub-beams, involving first coherent combining and then spectral combining, can achieve high-power, miniaturized laser combining with a simple structure. Summary of the Invention

[0007] (a) Purpose of the invention Current laser sub-beam arrangement and synthesis methods for spectral synthesis limit the number of sub-beams involved in the synthesis, making it difficult to improve the output power of spectral synthesis. This invention proposes a two-dimensional coherent spectral recombination synthesis device and method to solve this problem.

[0008] (II) Technical Solution To address the aforementioned technical problems, this invention provides a two-dimensional coherent and spectral composite synthesis device and method to increase the number of narrow-linewidth laser sub-beam sources. First, in the vertical direction, narrow-linewidth laser sub-beams of the same wavelength are coherently synthesized using a common aperture, degenerating the two-dimensional array of sub-beams into a one-dimensional array. Then, in the horizontal direction, narrow-linewidth laser sub-beams of different wavelengths are spectrally synthesized, ultimately achieving an increase in the output power of the synthesized beam.

[0009] The two-dimensional coherent and spectral composite synthesis device of the present invention includes a laser sub-beam group 1, a coherent synthesis element 2, an optical conversion device 3, and a dielectric film grating 4.

[0010] First, the narrow-linewidth laser sub-beams in laser sub-beam group 1 are arranged in a two-dimensional structure, where the wavelength of each column of narrow-linewidth laser sub-beams is the same. For example, the wavelength of the first column is λ1, the wavelength of the second column is λ2, ..., and the wavelength of the nth column is λ. n .

[0011] Subsequently, after passing through coherent combining element 2, each column of narrow-linewidth laser sub-beams with the same wavelength in the longitudinal direction is combined into a single beam emitted from the same aperture. The coherently combined emission positions are at the same height, thus transforming the two-dimensional narrow-linewidth laser sub-beams into a one-dimensional structure. At this point, the wavelengths of each beam are different, such as... Figure 2 As shown.

[0012] Secondly, sub-beams of different wavelengths are arranged in a one-dimensional structure and incident in parallel to each other into the optical conversion device 3. The beams are converted from being parallel to each other into a converging state and finally converge onto the dielectric film grating 4 for spectral synthesis and then emitted out at the same diffraction angle φ.

[0013] Different center wavelengths λ of the converging beam i , and the incident angle θ on the dielectric grating i The emission angle φ and the grating period d satisfy the grating diffraction equation relationship: d*(sinθ i ±sinφ)= mλ i m represents the diffraction order of the grating. When the incident and outgoing beams are on the same side of the grating normal, the value inside the parentheses is positive; when they are on opposite sides of the grating normal, the value inside the parentheses is negative.

[0014] In this embodiment, the coherent and spectral recombination synthesis of two-dimensional structures involves the following key technical points: S1 laser sub-beam arrangement: The laser sub-beams are arranged in parallel according to a two-dimensional structure. The wavelengths of each sub-beam are the same in the longitudinal direction, but the wavelengths are different in the transverse direction. S2 Sub-beam Dimensional Degradation: After coherent combining, each column of laser sub-beams of the same wavelength is emitted at the same height in a common aperture manner. The laser sub-beams degenerate from a two-dimensional structure to a one-dimensional structure arrangement and maintain a parallel state with each other. S3 coherent spectral synthesis: The narrow linewidth laser sub-beams are first coherently synthesized, and then spectral synthesis is performed, rather than coherent spectral synthesis being performed simultaneously.

[0015] Preferably, the number of laser sub-beams in each column along the longitudinal direction can be the same or different; Preferably, the coherent combining element 2 can be a single optical element or a combination of multiple optical elements. Preferably, the optical conversion device 3 can be one or more of the following optical elements or combinations: dielectric film grating, parabolic cylindrical mirror, cylindrical lens, cylindrical mirror group, cylindrical lens group, etc., but is not limited to the optical elements mentioned above.

[0016] (III) Beneficial Effects The coherent spectral composite synthesis device and method for two-dimensional structures provided by the above technical solution, by extending the laser sub-beams to the arrangement of two-dimensional structures and adopting coherent spectral composite synthesis, achieves an increase in the number of laser sub-beams compared with existing spectral synthesis devices and methods, enabling the synthesis of higher power beams and miniaturized design of the synthesis device. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the two-dimensional coherent spectral composite synthesis device according to Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the sub-beam wavelength arrangement in the laser sub-beam group of Embodiment 1 of the present invention, and the sub-beam wavelength arrangement after coherent combining; Figure 3 This is a schematic diagram of the two-dimensional coherent spectral composite synthesis device according to Embodiment 2 of the present invention; Figure 4 This is a schematic diagram of the sub-beam wavelength arrangement in the laser sub-beam group of Embodiment 2 of the present invention, and the sub-beam wavelength arrangement after coherent synthesis. Detailed Implementation

[0018] To make the objectives, contents, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0019] Example 1 like Figure 1 , Figure 2 As shown, the coherent and spectral composite combining device of the two-dimensional structure in this embodiment includes a laser sub-beam group 1, a coherent combining element 2, an optical conversion device 3, and a dielectric film grating 4 arranged sequentially along the optical path. The laser sub-beam group 1 emits m rows × n columns of laser sub-beams to the coherent combining element 2, which combine them into a 1 row × n column output beam. The beam is then further converged by the optical conversion device 3 to the dielectric film grating 4, and finally output as a combined beam.

[0020] Among them, laser sub-beam group 1 consists of multiple narrow-linewidth fiber lasers, typically collimated by a quartz QBH, arranged in a two-dimensional structure in the near field. Each laser sub-beam has the same polarization direction in the longitudinal direction and the same wavelength, namely λ1, λ2, ..., λ... n Each wavelength has m sub-beams, resulting in a total of m×n narrow-linewidth laser sub-beams.

[0021] The m×n narrow-linewidth laser beams are collimated and paralleled to the coherent combining element 2. After phase-locked loop control, coherent combining occurs, and the narrow-linewidth laser sub-beams with the same wavelength from each column are combined into one beam. The sub-beam array degenerates into n one-dimensionally arranged sub-beams of different wavelengths, with wavelengths still λ1, λ2, ..., λn. n ,like Figure 2 As shown.

[0022] The optical conversion device 3 can be one of the optical elements such as a dielectric film grating, a parabolic cylindrical mirror, a cylindrical lens, a cylindrical mirror group, or a cylindrical lens group, but is not limited to the optical elements mentioned above.

[0023] The optical conversion device 3 is set at a specific angle, so that each laser sub-beam with a different wavelength is at a different specific angle θ. i When incident on the dielectric grating, the light undergoes diffraction by the dielectric grating 4 and has the same diffraction angle, thus satisfying the grating diffraction equation: d*(sinθ i ±sinφ)= mλ i , Where d is the grating constant of the dielectric grating 4, m is the diffraction order of the dielectric grating 4, and λ i Let θ be the wavelength of the i-th laser sub-beam. i φ is the incident angle of the i-th laser sub-beam after passing through the optical conversion device 3 and being incident on the dielectric film grating 4, and φ is the diffraction angle after being diffracted by the dielectric film grating 4.

[0024] Ultimately, each laser sub-beam exits at the same diffraction angle φ, achieving spectral synthesis.

[0025] Example 2 like Figure 3 , Figure 4As shown, the coherent spectral synthesis of 12 narrow-linewidth laser sub-beams arranged in two dimensions is taken as an example. Originally, laser sub-beam group 1 was arranged in one dimension, which could only accommodate 3 laser sub-beams with wavelengths of λ1=1050nm, λ2=1064nm, and λ3=1072nm. After two-dimensional expansion, in the vertical direction, each column of laser sub-beams with the same wavelength is expanded to 4 channels, and a total of 3×4=12 laser sub-beams can be used for synthesis, thus realizing the expansion of the number of laser sub-beams.

[0026] After each laser sub-beam passes through coherent combining element 2, laser sub-beams of the same wavelength undergo coherent combining with a common aperture, combining 4 channels into one channel, and combining 12 channels into 3 channels.

[0027] The optical conversion device 3 is also a dielectric film grating, with the same line density as the dielectric film grating 4, both being 1740 lines / mm. The two dielectric film gratings are placed in parallel to form a dual-grating spectral synthesis device.

[0028] The sub-beams emitted after coherent synthesis are incident on the dielectric film grating 3 (i.e., optical conversion device 3) at an incident angle of 63.5° and diffract. The light paths converge at the surface of the dielectric film grating 4. Finally, the sub-beams are still diffracted on the surface of the dielectric film grating 4 at a diffraction angle of 63.5°, forming a high-power combined beam, thus completing the coherent spectral recombination process.

[0029] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A two-dimensional coherent spectral recombination synthesis device, characterized in that, It includes a laser sub-beam group (1), a coherent combining element (2), an optical conversion device (3), and a dielectric film grating (4) arranged sequentially along the optical path. The laser sub-beam group (1) emits m rows × n columns of laser sub-beams to the coherent combining element (2), which combine them into a 1 row × n column output beam. The beam is then further converged by the optical conversion device (3) to the dielectric film grating (4), and finally output as a combined beam.

2. The coherent spectral composite synthesis apparatus with a two-dimensional structure as described in claim 1, characterized in that, The narrow linewidth laser sub-beams in the laser sub-beam group (1) are arranged in a two-dimensional structure, and the wavelengths of each column of narrow linewidth laser sub-beams are the same.

3. The two-dimensional coherent spectral composite synthesis apparatus as described in claim 2, characterized in that, After passing through the coherent combining element (2), each column of narrow linewidth laser sub-beams with the same wavelength in the longitudinal direction is combined into a beam emitted from the same aperture. The coherently combined emission positions are at the same height, and the two-dimensional narrow linewidth laser sub-beams are arranged in a one-dimensional structure, with each beam having a different wavelength.

4. The coherent spectral recombination synthesis apparatus with a two-dimensional structure as described in claim 3, characterized in that, The optical conversion device (3) receives sub-beams of different wavelengths arranged in a one-dimensional structure and incident in parallel. It converts each beam from a state of mutual parallelism to a convergent state and converges them onto the dielectric film grating (4) to perform spectral synthesis and emit them out at the same diffraction angle φ.

5. The coherent spectral recombination synthesis apparatus with a two-dimensional structure as described in claim 4, characterized in that, The optical conversion device (3) outputs a converging beam with different center wavelengths λ. i , and the incident angle θ on the dielectric grating i The emission angle φ and the grating period d satisfy the grating diffraction equation relationship: d*(sinθ i ±sinφ)= mλ i m represents the diffraction order of the grating. When the incident and outgoing beams are on the same side of the grating normal, the value inside the parentheses is positive; when they are on opposite sides of the grating normal, the value inside the parentheses is negative.

6. The coherent spectral recombination synthesis apparatus with a two-dimensional structure as described in claim 5, characterized in that, In the two-dimensional arrangement of laser sub-beams (1), the number of laser sub-beams in each column along the longitudinal direction is the same or different.

7. The coherent spectral recombination synthesis apparatus with a two-dimensional structure as described in claim 6, characterized in that, The coherent combining element (2) is a single optical element or a combination of multiple optical elements.

8. The coherent spectral recombination synthesis apparatus with a two-dimensional structure as described in claim 7, characterized in that, The optical conversion device (3) is one of the following: dielectric film grating, parabolic cylindrical mirror, cylindrical lens, cylindrical mirror group, and cylindrical lens group.

9. A method for coherent, spectral recombination synthesis of a two-dimensional structure, characterized in that, Coherent and spectral composite synthesis is performed using the synthesis system described in any one of claims 1-8.

10. The method for coherent and spectral recombination synthesis of two-dimensional structures as described in claim 9, characterized in that, The method is as follows: First, in the vertical direction, narrow linewidth laser sub-beams of the same wavelength are coherently combined with a common aperture to degenerate the two-dimensional array of sub-beams into a one-dimensional array. Then, in the horizontal direction, narrow linewidth laser sub-beams of different wavelengths are spectrally combined to ultimately improve the output power of the combined beam.

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