基于波长啁啾分布的高亮度锥形半导体激光阵列密集谱合束技术

Aiming the imperfect beam quality of diode laser source for the field of laser precise cutting and 3D printing, the dense spectral combining technology of wavelength-chirped high brightness tapered diode laser bars is proposed in this project. We intend to begin this project from the development of diode laser chip. By introducing the high-gain active region, enlarging the waveguide structure to spread the optical mode, integrating the high-order frequency-stabilized grating and the optical-amplify taper structure, the deterioration of beam quality caused by the high-order-mode crosstalk can be solved efficiently. A high brightness wavelength-chirped diode laser array is realized, the output power reach 30 watts. The wavelength of array covers the range from 973nm to 979nm, the space of center.wavelength of each emitter is 1.5nm. The laser array is combined by the technology of dense spectral combining. By resolution the key technology such as the high precisely temperature control of volume Bragg gratings, a high beam quality diode laser source with an output power＞100 watts and M²＜4 is obtained, which offers a practicable guidance for the development of near-diffraction-limited high power diode laser source.

针对目前半导体激光光源光束质量不够理想，难以满足激光精细切割、激光3D打印等领域的要求，本项目提出基于波长啁啾分布的高亮度锥形半导体激光阵列的密集谱合束技术研究。拟从芯片研制出发，引入高增益新型发光区、模式扩展超宽波导结构、高阶稳频集成化光栅及锥形放大区结构，解决现阶段传统激光芯片多模式串扰引起的光束质量下降问题，研制出实用化的波长啁啾分布的高亮度锥形半导体激光阵列，阵列出光波长覆盖973nm-979nm，发光单元波长间隔1.5nm，功率＞30W；利用密集谱合束技术对所研制的激光阵列进行合束，解决体布拉格光栅的高精度温度控制等关键技术，研制出输出功率＞100W，M²＜4的高光束质量半导体激光光源，为今后大功率、近衍射极限光束质量输出的半导体激光光源的研制奠定基础。

鉴于目前工业中对直接输出的高光束质量半导体激光光源的迫切应用需求，针对现阶段制约高光束质量半导体激光光源发展的芯片结构、器件工艺及合束技术的关键理论及技术问题，本项目开展了以下研究内容：（1）对高亮度芯片增益材料及超宽模式扩展波导结构设计进行了研究，优化了材料结构，减小了内部材料吸收，提高了芯片功率及亮度；（2）对高阶DFB啁啾光栅集成脊形模式滤波区及锥形放大区结构进行了优化设计，解决了光丝效应，实现了高亮度锥形半导体激光阵列的大功率输出；（3）开展对具有高性能波长啁啾光栅的高亮度锥形激光阵列制备的工艺研究，实现了脊形滤波区与锥形放大区的高精度接合，减小了器件内部光泄露；（4）通过采用波长啁啾分布的高亮度锥形半导体激光阵列密集谱合束技术，解决了多路VBG的单路高精度温控，保证了VBG的高衍射效率。最终研制出了实用化的波长啁啾分布的高亮度锥形半导体激光阵列，阵列出光波长覆盖973nm-979nm，发光单元波长间隔1.5nm，功率32W；研制出了输出功率102W，M²≈3.87的高光束质量半导体激光光源，该技术也适用于其他波段的半导体激光器的研制，以本项目研制的激光光源为单元模块，与其他波段的半导体激光光源实现波长合束，可进一步提高输出功率，有望在激光加工领域取代光纤激光器，具有极为深远的科学意义。