Wünsche Martin, Fuchs Silvio, Aull Stefan, Nathanael Jan, Möller Max, Rödel Christian, Paulus Gerhard G
Opt Express. 2017 Mar 20;25(6):6936-6944. doi: 10.1364/OE.25.006936.
A quasi-supercontinuum source in the extreme ultraviolet (XUV) is demonstrated using a table-top femtosecond laser and a tunable optical parametric amplifier (OPA) as a driver for high-harmonic generation (HHG). The harmonic radiation, which is usually a comb of odd multiples of the fundamental frequency, is generated by near-infrared (NIR) laser pulses from the OPA. A quasi-continuous XUV spectrum in the range of 30 to 100 eV is realized by averaging over multiple harmonic comb spectra with slightly different fundamental frequencies and thus different spectral spacing between the individual harmonics. The driving laser wavelength is swept automatically during an averaging time period. With a total photon flux of 4×10 photons/s in the range of 30 eV to 100 eV and 1×10photons/s in the range of 100 eV to 200 eV, the resulting quasi-supercontinuum XUV source is suited for applications such as XUV coherence tomography (XCT) or near-edge absorption fine structure spectroscopy (NEXAFS).
利用桌面型飞秒激光器和可调谐光学参量放大器（OPA）作为高次谐波产生（HHG）的驱动源，展示了一种极紫外（XUV）波段的准超连续谱源。谐波辐射通常是基频奇倍数的梳状谱，由OPA产生的近红外（NIR）激光脉冲产生。通过对多个基频略有不同因而各谐波之间光谱间距也不同的谐波梳状谱进行平均，实现了30至100电子伏特范围内的准连续XUV光谱。在平均时间段内，驱动激光波长会自动扫描。在30电子伏特至100电子伏特范围内总光子通量为4×10光子/秒，在100电子伏特至200电子伏特范围内为1×10光子/秒，由此产生的准超连续谱XUV源适用于诸如XUV相干断层扫描（XCT）或近边吸收精细结构光谱（NEXAFS）等应用。
