【作者】 凌光鹏；

【导师】 韩一平；

【作者基本信息】 西安电子科技大学 ， 光学， 2011， 硕士

【摘要】 随着激光技术的日益发展,人们已经成功的将激光脉宽从ns量级缩短到了fs量级,同时随着激光脉冲峰值功率的不断提高,激光与光学系统的相互作用研究进入了全新的领域。光学薄膜几乎是光学系统中不可或缺的元件,同时也是整个系统中最薄弱的环节,因而光学薄膜的激光损伤问题一直是激光向高能量、高功率方向发展的瓶颈。所以,研究光学薄膜的抗激光破坏问题具有非常重要的意义和实用价值。脉冲激光对光学薄膜损伤是一个复杂的过程,常常伴随几种损伤机制的出现。本文主要探讨短脉冲激光以及飞秒脉冲激光对薄膜的损伤问题。首先从短脉冲激光的损伤问题出发,然后扩展到飞秒脉冲。通过建立热冲击效应模型,以类金刚石和铝膜反射镜为例,求解了在短脉冲激光作用下,它们了的温度分布以及热应力分布。在此基础上,把激光脉宽从纳秒级别缩短到飞秒级别,介绍了在飞秒脉冲激光作用下,几种经典的能量输运模型。通过构造双温两步模型,以200nm金膜为例,深入的探讨了在飞秒脉冲激光作用下,光学薄膜的热损伤行为。结果表明,在飞秒脉冲激光作用下,光学薄膜的损伤阈值已经不再遵从传统的? 1/2标度律,经典的Fourier热传导模型已经失效。更多还原

【Abstract】 Along with the development of laser technology, the durations of laser pulse have been compressed successfully from ns to the order of fs, and with the improvement of laser pulse peak power, as a result, the research on the interaction between laser and materials has been advanced to completely new stage. As the essential basic component of almost all optical systems, optical films are the weakest link in the whole systems, thus ,the laser damage of optical thin films has been the bottleneck of high-energy, high-power direction of lasers. Therefore, it is very significant and valuable to research the damage of optical thin-film by lasers.The damage of optical thin films by pulsed laser is a complex process, it is often accompanied by the emergence of several mechanisms of damage. The damage of optical thin films by the short pulse laser and the femtosecond pulse laser is analyzed in this paper. First, from short pulse laser damage, and then, it is extended to the femtosecond pulse. Through the establishment of thermal shock effect model, we solve the temperature distribution and thermal stress distribution of diamond-like carbon and aluminum reflector in short pulse lasers. On this basis, we compress the laser pulse from the order of nanosecond to femtosecond , introduce several classical energy transport models in the femtosecond laser pulse. By constructing a two-temperature and two-step model, discussing the damage of optical thin films in 200nm gold film by the femtosecond pulse laser. It suggests that the laser damage threshold of materials disobeys the ? 1/2 law, it can not be treated by the classical fourier thermal conduction theory.更多还原