Breitkopf Sven, Wunderlich Stefano, Eidam Tino, Shestaev Evgeny, Holzberger Simon, Gottschall Thomas, Carstens Henning, Tünnermann Andreas, Pupeza Ioachim, Limpert Jens
1Institute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, Albert-Einstein-Str. 15, 07745 Jena, Germany.
Active Fiber Systems GmbH, Wildenbruchstr. 15, 07745 Jena, Germany.
Appl Phys B. 2016;122(12):297. doi: 10.1007/s00340-016-6574-x. Epub 2016 Dec 2.
Periodic dumping of ultrashort laser pulses from a passive multi-MHz repetition-rate enhancement cavity is a promising route towards multi-kHz repetition-rate pulses with Joule-level energies at an unparalleled average power. Here, we demonstrate this so-called stack-and-dump scheme with a 30-m-long cavity. Using an acousto-optic modulator, we extract pulses of 0.16 mJ at 30-kHz repetition rate, corresponding to 65 stacked input pulses, representing an improvement in three orders of magnitude over previously extracted pulse energies. The ten times longer cavity affords three essential benefits over former approaches. First, the time between subsequent pulses is increased to 100 ns, relaxing the requirements on the switch. Second, it allows for the stacking of strongly stretched pulses (here from 800 fs to 1.5 ns), thus mitigating nonlinear effects in the cavity optics. Third, the choice of a long cavity offers increased design flexibility with regard to thermal robustness, which will be crucial for future power scaling. The herein presented results constitute a necessary step towards stack-and-dump systems providing access to unprecedented laser parameter regimes.
从被动式多兆赫兹重复频率增强腔中周期性地输出超短激光脉冲，是一条有望获得兆赫兹重复频率脉冲且具有焦耳级能量以及无与伦比平均功率的途径。在此，我们展示了这种所谓的堆叠与输出方案，采用的是一个30米长的腔。利用一个声光调制器，我们以30千赫兹的重复频率提取出能量为0.16毫焦的脉冲，对应65个堆叠的输入脉冲，相较于之前提取的脉冲能量有三个数量级的提升。这个比之前长十倍的腔相较于以前的方法有三个重要优势。第一，后续脉冲之间的时间增加到100纳秒，放宽了对开关的要求。第二，它允许堆叠强烈拉伸的脉冲（此处从800飞秒到1.5纳秒），从而减轻腔光学中的非线性效应。第三，选择长腔在热稳定性方面提供了更大的设计灵活性，这对于未来的功率扩展至关重要。本文所展示的结果是迈向堆叠与输出系统的必要一步，该系统能够实现前所未有的激光参数范围。
