Abstract

In the last decade the use of laser beam filamentation has become of great interest, not only as a complex physical process, but also applied to the compression of femtosecond pulses. In particular, it has been reported that at some particular experimental conditions the pulse can experience a self-compression effect [1]. This phenomenon has been recently obtained by controlling the chirp of the input [2]. For this reason we have studied the impact of the input chirp over the temporal structure of the pulses generated after the filamentation process. During those scans, very rich pulse structures and pulse splitting dynamics has been observed. Particularly, for each input energy studied, we found two different input chirp values (oppositely signed) that produce a single filament self-compressed pulse. Fig. 1 shows the data measured in the 5 mJ input energy case, obtaining 22 and 25 fs when using input pulses with positive or negative input chirp, respectively. Similar results were obtained from a systematic study realized for input energies between 3 and 5 mJ [2]. The energy transmission in the inner core remains constant at 20 % in all the cases.

© 2011 Optical Society of America