聚焦激光在KDP晶体中的传输特性模拟

Simulation of transmission characteristics of focused laser inside KDP crystal

激光在KDP晶体中制作3维微结构是抑制高功率激光驱动器中横向受激喇曼散射效应的一种有效方法。为了了解激光制作微结构的可行性以及激光参量对制作精度、效率和成品率的影响,对聚焦激光在KDP晶体中的传输特性进行了数学模拟研究。激光焦点峰值功率密度、光斑畸变和位置偏移是影响制作精度和造成晶体碎裂的主要因素;e光焦点形貌会随着晶体光轴与入射激光的夹角增大而发生畸变,其峰值功率密度随着夹角的增大而迅速减小。结果表明,当夹角小于15°,e光焦点可使加工效率提升1倍以上;当夹角大于30°,低能量加工其影响可忽略,高能量加工则极易造成晶体碎裂,应对e光进行屏蔽。

Laser producing 3-D microstructures inside KDP crystals is an effective way to suppress the transverse stimulated Raman scattering（TSRS） effect in high power lasers. The transmission characteristics of focused laser inside KDP crystal was simulated to investigate the feasibility of laser making 3-D microstructures and the effects of laser parameters on the machining accuracy, efficiency and success rates. The effects of the focus peak power density, spot distortion and the migration are the main factors affecting the machining accuracy and causing crystal fragmentation. The size and shape of the e-polarization focus will distort and its peak power density decreases rapidly with the increasing of angle between incident laser and crystal optical axis. The results show that the effect of the e-polarization laser will increase the processing efficiency more than twice when the angle is less than 15° and can be neglected in the low-energy or cause crystal fragmentation easily in high-energy when the angle is greater than 30°.