Chen Shunli, Gao Pengpeng, Zhao Yuanan, Wang Yanzhi, Fang Zhou, Leng Yuxin, Shao Jianda
Appl Opt. 2014 May 20;53(15):3347-54. doi: 10.1364/AO.53.003347.
The laser-induced damage behaviors of chirped mirrors (CMs) are studied by single 800 nm, 38 fs lasers. The CMs provide group delay dispersion of around -60 fs² and average reflectivity of about 99.4% with bandwidth range of 200-300 nm at a central wavelength of 800 nm. Interestingly, a circular blister feature appears in the CMs at a wide range of laser fluence. An optical microscope, atomic force microscope, scanning electron microscope, and surface profiler are applied to describe the blister characteristics. An adiabatic expansion model of ideal gas is adopted to illustrate the formation dynamics of blisters. The evolution of blisters can be explained by partial evaporation of the film and a subsequent gas expansion, driving the bulging of the film stack up to the stress limit, where the blister fractures. According to this model, the energy absorption ratio of blisters increases monotonously with increasing laser fluence before the occurrence of the focal spot confinement effect.
采用单束800nm、38fs激光研究了啁啾镜（CMs）的激光诱导损伤行为。这些啁啾镜在中心波长800nm处提供约-60 fs²的群延迟色散和约99.4%的平均反射率，带宽范围为200 - 300nm。有趣的是，在很宽的激光能量密度范围内，啁啾镜中都会出现圆形气泡特征。使用光学显微镜、原子力显微镜、扫描电子显微镜和表面轮廓仪来描述气泡的特性。采用理想气体的绝热膨胀模型来说明气泡的形成动力学。气泡的演变可以通过薄膜的部分蒸发以及随后的气体膨胀来解释，这会驱使薄膜堆叠鼓起直至达到应力极限，此时气泡破裂。根据该模型，在焦斑限制效应出现之前，气泡的能量吸收率随激光能量密度的增加而单调增加。
