Analysis of pulse front tilt in simultaneous spatial and temporal focusing.

Simultaneous spatial and temporal focusing (SSTF) has gained enormous interest for controlling the focal region of ultrashort pulses in the material processing community. In this paper, we provide theoretical insight in the nature of SSTF. We use numerical simulations to propagate the initial pulse through the focusing lens and into the focal region. By that we can investigate the appearance of the pulse front tilt (PFT), which has been experimentally obtained in SSTF. This is further deepened by a mathematical investigation which shows that PFT is a fundamental consequence of SSTF. Next we follow the idea to use an initial PFT in order to influence or even compensate the PFT in the focal region. Again that is done by simulations as well as mathematical investigations. We found that an initial PFT cannot significantly influence the PFT in the focal region.