Adiabatic Interactions and Frequency Conversion Processes: Investigations and Applications

强的相干辐射与物质的相互作用是最近基于激光的科学的重大兴趣。这些相互作用不仅依赖于高强度的激光辐射，还依赖于相干特性。在成功应用的相互作用中，有基于绝热通过过程的技术。由于它们对实验参数的波动具有稳健性，因此具有特殊的意义。虽然绝热过程通常是用中等强度的相当长的辐射脉冲来实现的，但许多应用需要相互作用，由高强度的短激光脉冲驱动。我们将研究短激光脉冲驱动的相干绝热相互作用在涉及多光子跃迁的量子系统中的应用，在具有快速退相过程的稠密气体介质中的应用，以及非线性光学频率转换过程。研究的重点是在相干制备的大密度气体介质中进行高效的低阶和高阶频率转换。特别是，其目的是为短波长辐射和超宽带光谱提供新的、有效的来源。例如，对于接近亚飞秒时间域的超短激光脉冲的产生来说，这些是相当有意义的。

Interactions of strong, coherent radiation with matter are of significant interest to recent laserbased science. These interactions do not rely on the high intensity of laser radiation only, but also on the coherence properties. Among the successfully applied interactions are techniques, based on adiabatic passage processes. These are of special interest due to their robustness with respect to fluctuations in the experimental parameters. While adiabatic processes are usually implemented with rather long radiation pulses at moderate intensities, many applications require interactions, driven by short laser pulses at high intensities. We will investigate coherent, adiabatic interactions, driven by short laser pulses, with regard to applications in quantum systems involving multi-photon transitions, in dense gaseous media with fast dephasing processes, and to nonlinear optical frequency conversion processes. The investigations focus on efficient low-order and high-order frequency conversion in coherently prepared, gaseous media of large densities. In particular, the aim is to provide novel, efficient sources for shortwavelength radiation and ultra-broadband spectra. These are of considerable interest, e.g. for the generation of ultra-short laser pulses, approaching the sub-femtosecond time domain.