不同工艺条件下TiO_2单层膜的吸收和损伤阈值测试

Absorption and Laser Induced Damage Threshold of TiO_2 Single Films under Different Process Conditions

利用电子束热蒸发技术在不同氧分压和烘烤温度下镀制了一系列TiO2单层膜,采用表面热透镜技术测量了样品在1064nm处的弱吸收值,并用激光损伤测试平台测量了样品的抗激光损伤阈值(LIDT)特性。实验结果表明较高的氧分压和较低的烘烤温度能显著减小薄膜的吸收值。不过薄膜在基频下的损伤阈值除了受到薄膜吸收值的影响外,还取决于基底表面的杂质密度,当薄膜吸收较大时,本征吸收对损伤破坏起到主要作用;随着薄膜的吸收逐渐减小,基底表面处的缺陷吸收逐渐取代本征吸收成为影响薄膜损伤阈值的主导因素。

A series of TiO2 single films with different oxygen partial pressures and baking temperatures are prepared by electron beam evaporation.Both the absorption and the laser induced damage threshold（LIDT） at the wavelength of 1064 nm are measured.The results show that by improving oxygen partial pressure or reducing baking temperature,the film absorption can be reduced obviously.As for the LIDT of the TiO2 films at 1064 nm,it is affected by not only the absorption but also the quality of the substrate surface.When the absorption of the coating is high,the intrinsic absorption is dominant in the laser damage process.However,when the absorption of the coating is low enough,even bits of impurities at the surface of the substrate lead to a sharp decline of the LIDT.