Nalam Samuel Anurag, Harsha S Sree, Kiran P Prem
Opt Express. 2021 May 10;29(10):14668-14681. doi: 10.1364/OE.422508.
Femtosecond laser pulse induced filamentation in atmosphere is susceptible to a number of input laser, focusing optics and medium characteristics. Filamentation of fs pulses in atmosphere is an intense propagation regime where the focusing geometry used to focus the fs laser pulses play an important role influencing the filament intensity and the associated supercontinuum. We identified different optical elements used for focusing the fs laser pulses leading to filamentation in air and classified them according to the induced aberrations. To clearly identify the role of aberrations, all the optical elements were taken to have same focal length. The subsequent filament structure and emissions from the filament were correlated with the aberrations induced by optical element revealed stark differences. The onset of the filamentation, its longitudinal intensity and the associated supercontinuum emission (SCE) have varied drastically with the aberrations induced by the focusing optics. A systematic study directed to choose and identify suitable optical elements according to the usage of the fs pulses for a specific filamentation regime is presented.
飞秒激光脉冲在大气中产生的丝状化现象易受多种因素影响，包括输入激光、聚焦光学器件和介质特性。飞秒脉冲在大气中的丝状化是一种强传播机制，用于聚焦飞秒激光脉冲的聚焦几何结构在影响丝状强度和相关超连续谱方面起着重要作用。我们识别了用于聚焦飞秒激光脉冲以在空气中产生丝状化的不同光学元件，并根据所诱导的像差对它们进行了分类。为了清楚地识别像差的作用，所有光学元件都采用相同的焦距。随后，丝状结构和来自丝状的发射与光学元件所诱导的像差相关，显示出明显的差异。丝状化的起始、其纵向强度以及相关的超连续谱发射（SCE）都随着聚焦光学器件所诱导的像差而发生了巨大变化。本文提出了一项系统研究，旨在根据飞秒脉冲在特定丝状化机制中的用途来选择和识别合适的光学元件。
