Effects of deposition rates on laser damage threshold of TiO₂/SiO₂ high reflectors

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• 作者：Jianke Yao ; Cheng Xu ; Jianyong Ma ; Ming Fang ; Zhengxiu Fan ; Yunxia Jin ; Yuanan Zhao ; Hongbo He ; Ji ; a Shao
• 关键词：TiO₂/SiO₂ high reflectors ; Laser damage ; Deposition rate ; Electron beam evaporation ; Raman spectra ; Energy dispersive X-ray analysis
• 刊名：Applied Surface Science
• 出版年：2009
• 出版时间：15 February 2009
• 年：2009
• 卷：255
• 期：9
• 页码：4733-4737
• 全文大小：603 K

文摘

TiO₂ single layers and TiO₂/SiO₂ high reflectors (HR) are prepared by electron beam evaporation at different TiO₂ deposition rates. It is found that the changes of properties of TiO₂ films with the increase of rate, such as the increase of refractive index and extinction coefficient and the decrease of physical thickness, lead to the spectrum shift and reflectivity bandwidth broadening of HR together with the increase of absorption and decrease of laser-induced damage threshold. The damages are found of different morphologies: a shallow pit to a seriously delaminated and deep crater, and the different amorphous-to-anatase-to-rutile phase transition processes detected by Raman study. The frequency shift of Raman vibration mode correlates with the strain in film. Energy dispersive X-ray analysis reveals that impurities and non-stoichiometric defects are two absorption initiations resulting to the laser-induced transformation.