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

Area of Science:

• Nonlinear Optics
• Ultrafast Laser Physics

Background:

• Self-focusing is a nonlinear optical phenomenon crucial for high-intensity light-matter interactions.
• Few-cycle light pulses exhibit unique nonlinear optical properties due to their broad spectra.
• Filamentation in air, a consequence of self-focusing, is used for pulse compression.

Purpose of the Study:

• Investigate the influence of the carrier-envelope phase (CEP) on self-focusing dynamics in air.
• Determine the critical power for self-focusing of few-cycle pulses in air.
• Compare experimental self-focusing distances with theoretical predictions based on CEP.

Main Methods:

• Generation of phase-stabilized few-cycle light pulses.
• Experimental measurement of the critical power for self-focusing in air.
• Observation and measurement of filamentation and self-focusing distances.
• Comparison of experimental data with first-order theoretical models.

Main Results:

• Measured critical power for self-focusing in air at 18±1 GW for 6.3 fs pulses at 800 nm.
• Predicted a 790 µm deviation in self-focusing distance with CEP shift from 0 to π/2 rad.
• Observed no significant deviation in experimental focal distance, with a 3σ upper limit of 180 µm.

Conclusions:

• Experimental results contradict theoretical predictions regarding CEP influence on self-focusing distance.
• The minimal observed deviation suggests complex nonlinear dynamics in the few-cycle regime.
• Further research is needed to fully understand self-focusing phenomena with few-cycle pulses.