高能量全固态激光器的透镜导管耦合系统设计

Design of Lens Duct Coupling System in High Energy All-Solid-State Laser

激光二极管阵列(LDA)的出射光束空间分布不均匀,发散角大,难以直接用于端面抽运的固体激光器中,需要对LDA输出光束进行整形耦合。用Zemax光学设计软件设计出一款适合端面抽运全固态激光器的耦合系统,该耦合系统由快轴准直镜与透镜导管组成。着重研究了透镜导管的耦合效率与透镜导管特征参数之间的关系,并通过光线追迹得出最佳耦合系统参数。设计的透镜导管长22 mm,输入面尺寸为12 mm(快轴)×9 mm(慢轴),输出面尺寸为3.5 mm×3.5 mm,输入端球面曲率半径为14 mm。该系统耦合效率可达90.7%,距输出端1 mm处的光束发散角为0.38 mrad(快轴)与0.02 mrad(慢轴),可使抽运光和固体激光器振荡光达到良好的光束匹配效果。

Due to inhomogeneous spatial distribution and large divergence angle of the laser diode array （LDA）, LDA is inconvenient for end-pumping solid-state lasers, and the output beam reshaping and coupling is required. A coupling system for end-pumping solid-state lasers is designed with Zemax. The system is composed of a fast axis collimating lens and a lens duct. The relationship between the coupling ef：ficiency and the characteristic parameters of the lens duct is studied. The optimal coupling system parameters are obtained by ray tracing. The final designed lens duct is 22 mm long, the input surface size is 12 mm （fast axis）×9 mm （slow axis）, the output surface size is 3.5 mm×3.5 mm, the radius of curvature is 14 mm, and the coupling efficiency can reach 90.7%. The beam divergence angle at 1 mm away from the lens duct is 0.38 mrad for fast axis and 0.02 mrad for slow axis. This system can make the pumping beam and the oscillating beam match well.