We investigated theoretically and experimentally the ultrafast birefringence induced by impulsive alignment in a molecular gas during optical filamentation. This phenomenon is able to substantially affect the polarization state of an ultrashort laser pulse that propagates through the aligned medium at suitable delays from a first aligning pulse. We exploited this modulation of the polarization state in order to effectively control the high-order harmonic generation (HHG) process, which is strongly dependent on the driving pulse polarization. These results open new and fascinating perspectives for the tailoring of strong-field phenomena by means of polarization pulse shaping.
© 2010 Optical Society of America
Original Manuscript: February 3, 2010
Manuscript Accepted: March 4, 2010
Published: April 23, 2010
M. Negro, C. Vozzi, F. Calegari, S. De Silvestri, and S. Stagira, "Polarization pulse shaping induced by impulsive molecular alignment in optical filamentation and application to high-order harmonic generation," Opt. Lett. 35, 1350-1352 (2010)