应用多孔径光束积分原理的LD端面抽运耦合系统

Laser diode end-pumped coupling system applying multi-aperture beam integration principle

提出了一种应用多孔径光束积分原理的新型LD端面抽运耦合系统。这种耦合系统将LD堆栈的入射光束分成许多细子光束,并通过会聚透镜聚焦在激光介质的抽运面上,得到高均匀性、高功率密度的抽运光斑。给出了具体的设计方法,并根据近轴矩阵光学ABCD定律推导了抽运光斑的发散角分布。针对5吧条的堆栈进行了耦合系统的具体设计,非序列光线追迹的结果表明:在抽运区域内获得均匀性良好的抽运光斑,快轴方向上的不均匀性(峰-谷值)小于3%,慢轴方向上的不均匀性小于6%,快慢轴方向的发散角分别为12°和16°,与传统的波导管方法相比,其结构更加紧凑灵活,同时能将抽运光束发散角控制在较小的范围内。

A novel end-pumped coupling optical system applying multi-aperture beam integration principle was presented. In the coupling system, the light of laser diode stack was divided into a number of beamlets. Subsequently these beamlets were overlapped in the pumped surface of laser media through a focusing lens. Then a high intensity and high homogeneity pumping field was obtained. The design method was put forward and the divergence angle distribution of pumping spot was analyzed through paraxial ABCD-matrix formalism. A coupling system applying 5 bars LD stack was designed as an example by ray tracing method. The non-sequential ray tracing simulation shows that a Top-Hat intensity pump profile was achieved at pumping surface and the nonhomogeneity （peak to valley value） is better than 3% in fast axes direction, and 6% in slow axes direction, the divergence angles of fast axes direction and slow axes direction are better than 12° and 16°. Comparing with the traditional wave-guide coupling optical system homogenization by means of microlens arrays, the structure is more flexible and more compact, and can control its beam divergence angle in a reasonable range.