Jansen G S M, Liu X, Eikema K S E, Witte S
Opt Lett. 2019 Aug 1;44(15):3625-3628. doi: 10.1364/OL.44.003625.
We demonstrate direct dispersion measurements of various thin films at extreme ultraviolet (EUV) wavelengths, using a table-top laser-driven high-harmonic generation (HHG) source. In this method, spatially separated identical EUV pulses are generated through HHG with a pair of phase-locked infrared pulses. The EUV pulses are re-imaged to a sample plane using a single toroidal mirror, such that one pulse illuminates the target thin film, while the other pulse passes through a reference aperture. By comparing the EUV interference with and without a sample, we are able to extract the dispersion properties of the sample, integrated over the full film thickness. We have measured thin films of titanium, nickel, copper, and silicon nitride, demonstrating that this technique can be applied to a wide range of materials, only requiring a film thin, enough for sufficient EUV transmission.
我们展示了使用桌面型激光驱动高次谐波产生（HHG）源在极紫外（EUV）波长下对各种薄膜进行直接色散测量。在这种方法中，通过HHG利用一对锁相红外脉冲产生空间分离的相同EUV脉冲。使用单个环形镜将EUV脉冲重新成像到样品平面，使得一个脉冲照射目标薄膜，而另一个脉冲通过参考孔径。通过比较有样品和无样品时的EUV干涉，我们能够提取样品在整个薄膜厚度上积分的色散特性。我们测量了钛、镍、铜和氮化硅薄膜，证明该技术可应用于广泛的材料，仅要求薄膜足够薄以实现足够的EUV透射。
