Self-focusing in air with phase-stabilized few-cycle light pulses

Abstract

We investigate the nonlinear optical phenomenon of self-focusing in air with phase-stabilized few-cycle light pulses. This investigation looks at the role of the carrier-envelope phase by observing a filament in air, a nonlinear phenomenon that can be utilized for few-cycle pulse compression [Appl. Phys. B79, 673 (2004)]. We were able to measure the critical power for self-focusing in air to be 18᱿GW for a 6.3 fs pulse centered at 800 nm. Using this value and a basic first-order theory, we predicted that the self-focusing distance should deviate by 790?孠as the carrier-envelope phase is shifted from 0 to p/2?rad. In contrast, the experimental results showed no deviation in the focus distance with a 3s upper limit of 180?孮 These counterintuitive results show the need for further study of self-focusing dynamics in the few-cycle regime.