飞秒激光作用下啁啾镜膜层内损伤相关动力学

发布时间：2018-05-17 04:05

本文选题：激光诱导损伤 + 啁啾镜　；参考：《红外与激光工程》2017年11期

【摘要】：光学元器件的激光损伤问题,一直以来都困扰着超强超短激光系统的进一步发展。飞秒激光领域,激光脉冲引起的光学器件损伤主要由材料的本征特性决定。光学材料内的多光子电离、雪崩电离、导带电子弛豫等一系列非线性过程,与材料的激光损伤过程密切相关。利用泵浦探测技术,采用中心波长为800 nm,重复频率1 k Hz的飞秒激光脉冲,对Nb2O5/Si O2啁啾镜介质膜的内部与飞秒激光损伤相关的超快动力学进行了研究。发现强的泵浦光脉冲辐照结束后飞秒乃至几十皮秒的范围内,啁啾镜对探测光的反射率有一定程度的下降。反射率降低的主要原因是泵浦光在介质膜的Nb2O5层内激发的大量的自由电子对探测光吸收所致,且该过程对激光诱导损伤过程起主导作用。通过反射率的变化,对其介质膜内导带电子弛豫过程进行探究,测定得到其衰减寿命,分别为1.31、6.88、22.34 ps。
[Abstract]:The problem of laser damage of optical components has been puzzling the further development of ultrashort laser system. In femtosecond laser field, the damage of optical devices caused by laser pulses is mainly determined by the intrinsic characteristics of materials. A series of nonlinear processes, such as multiphoton ionization, avalanche ionization and electron relaxation, are closely related to the laser damage process of optical materials. The ultrafast dynamics related to femtosecond laser damage in Nb2O5/Si O 2 chirped mirror dielectric films were studied by using pump detection technique using femtosecond laser pulses with a central wavelength of 800 nm and repetition frequency of 1 kHz. It is found that in the range of femtosecond or even tens of picoseconds after intense pump pulse irradiation, the reflectivity of the chirped mirror to the probe light decreases to a certain extent. The main reason for the decrease of reflectivity is the absorption of a large number of free electrons in the Nb2O5 layer of the dielectric film, which plays a leading role in the laser-induced damage process. Through the change of reflectivity, the electron relaxation process of conduction band in the dielectric film was investigated, and the decay life of the film was determined to be 1.31 ~ 6.88 ~ 22.34 ps respectively.
【作者单位】：中国科学院上海光学精密机械研究所强场激光物理国家重点实验室;中国科学院大学;中国科学院上海光学精密机械研究所中国科学院强激光材料重点实验室;电气通信大学先端超高速激光研究中心;
【基金】：中国科学院百人计划国家自然科学基金(61475169,11127901);国家自然科学基金创新群体项目(61521093)
【分类号】：TN249

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