Generation and applications of intense isolated attosecond pulses

Abstract

The exploration of electronic motion in real time as well as the control of electronic dynamics requires the development of new light sources in the XUV spectral region and with pulse durations of the order of attoseconds. One of the basic requirements for the examination and observation of such dynamics is to control the generation of these pulses. High-harmonic generation provides a powerful source of ultrashort coherent radiation in the XUV and soft-­x-ray range. For time domain spectroscopic applications,the exploitation of isolated attosecond pulses is more advantageous for the interpretation of the acquired data than a train of attosecond pulses. Isolated attosecond pulses are generated when XUV emission is confined with in half a cycle of the IR driving pulse. The non-linear medium is then emitting only one XUV light burst, i.e.a coherent XUV continuum. Nowadays, two possible solutions are proposed towards the generation of intense isolated attosecond pulses. The first approach requires the development of high-peak-power few-cycle laser systems, which are not commercially available, while the second approach utilizes the already commercially available high-peak-power many-cycles laser systems. In this thesis a new technique, which is called Interferometric Polarization Gating (IPG) is proposed, developed and implemented, based on the second approach. By appling this technique, the appropriate control of the high harmonic generation process is feasible leading to the generation of intense coherent XUV radiation. The energy content of this radiation is in the sub 100-nJ regime, which is currently the highest ever achieved energy in coherent XUV continuum generation. The temporal characterization of this radiation is made by means of 2nd order volume autocorellation (2-IVAC). The exploitation of these intense XUV continua in tracing ultrafast electronic dynamics in atomic systems is presented. This is the first experimental realization of an XUV-­ump-XUV-probe sequence. These intense coherent XUV continua allow for time-resolved linearand non-linear spectroscopy in this spectral region and thus are of great importance to a broad field of scientific disciplines.