Witte Stefan, Zinkstok Roel Th, Ubachs Wim, Hogervorst Wim, Eikema Kjeld S E
Laser Centre, Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam, Netherlands.
Science. 2005 Jan 21;307(5708):400-3. doi: 10.1126/science.1106612.
Precision spectroscopy at ultraviolet and shorter wavelengths has been hindered by the poor access of narrow-band lasers to that spectral region. We demonstrate high-accuracy quantum interference metrology on atomic transitions with the use of an amplified train of phase-controlled pulses from a femtosecond frequency comb laser. The peak power of these pulses allows for efficient harmonic upconversion, paving the way for extension of frequency comb metrology in atoms and ions to the extreme ultraviolet and soft x-ray spectral regions. A proof-of-principle experiment was performed on a deep-ultraviolet (2 x 212.55 nanometers) two-photon transition in krypton; relative to measurement with single nanosecond laser pulses, the accuracy of the absolute transition frequency and isotope shifts was improved by more than an order of magnitude.
紫外及更短波长的精密光谱学一直受到窄带激光器难以进入该光谱区域的阻碍。我们利用飞秒频率梳激光器产生的一列经相位控制的放大脉冲，展示了在原子跃迁上的高精度量子干涉计量。这些脉冲的峰值功率实现了高效的谐波上转换，为将原子和离子中的频率梳计量扩展到极紫外和软X射线光谱区域铺平了道路。我们在氪的深紫外（2×212.55纳米）双光子跃迁上进行了原理验证实验；相对于使用单纳秒激光脉冲的测量，绝对跃迁频率和同位素位移的测量精度提高了一个多数量级。
