亚飞秒啁啾Mo/Si多层膜反射镜的设计、制作与性能检测

针对利用高次谐波获取亚飞秒脉冲的实验需求,设计制备了啁啾为－2 800 as2的啁啾Mo/Si多层膜反射镜.数值计算表明,采用所设计的啁啾多层膜反射镜可以获得86 as的脉冲.通过直流磁控溅射方法实现了Mo/Si多层膜样品的制备.在合肥同步辐射上进行了多层膜反射率的测量,在所设计的工作波长内,多层膜的平均反射率为5.6±2.3%.在考虑最上层Si的氧化作用后,对测量曲线进行拟合,得到的反射率曲线和膜层厚度分布分别与测试曲线和设计结果相吻合.

Design,Fabrication and Characterization of the Chirped Mo/Si Multilayer Mirrors for Subfemtosecond Pulses

The chirped multilayer mirror with the chirp of －2 800 as2 is designed by using a genetic algorithm for subfemtosecond pulse from the high harmonics spectrum.The result of numerical simulation indicates that production of 86 as pulses can be achieved using the designed chirped multilayer mirror.The mirror is fabricated using magnetron sputtering method and characterized using the synchrotron radiation in Hefei.The average reflectivity is about 5.6±2.3% in the wavelength ragion of 12.5~16.5 nm.Considering the oxidization of the silicon layer at the vacuum boundary,the measured reflectivity curve is well fitted,and the layer thicknesses are matched with the designed one.