Hädrich S, Krebs M, Rothhardt J, Carstens H, Demmler S, Limpert J, Tünnermann A
Friedrich Schiller University Jena, Institute of Applied Physics, Albert-Einstein-Strasse 15, 07745 Jena, Germany.
Opt Express. 2011 Sep 26;19(20):19374-83. doi: 10.1364/OE.19.019374.
The process of high harmonic generation allows for coherent transfer of infrared laser light to the extreme ultraviolet spectral range opening a variety of applications. The low conversion efficiency of this process calls for optimization or higher repetition rate intense ultrashort pulse lasers. Here we present state-of-the-art fiber laser systems for the generation of high harmonics up to 1 MHz repetition rate. We perform measurements of the average power with a calibrated spectrometer and achieved µW harmonics between 45 nm and 61 nm (H23-H17) at a repetition rate of 50 kHz. Additionally, we show the potential for few-cycle pulses at high average power and repetition rate that may enable water-window harmonics at unprecedented repetition rate.
高次谐波产生过程能够将红外激光相干转换到极紫外光谱范围，从而开启了多种应用。该过程较低的转换效率要求对其进行优化，或者使用更高重复频率的强超短脉冲激光器。在此，我们展示了用于产生重复频率高达1兆赫兹的高次谐波的先进光纤激光系统。我们使用校准光谱仪测量了平均功率，并在50千赫兹的重复频率下，实现了45纳米至61纳米（H23 - H17）之间的微瓦级谐波。此外，我们还展示了在高平均功率和重复频率下产生少周期脉冲的潜力，这可能使水窗谐波能够以前所未有的重复频率产生。
