Yiftach Katzir

Control of the collapse distance in atmospheric propagation

We show experimentally for ultrashort laser pulses propagating in air, that the collapse/filamentation distance of intense laser pulses in the atmosphere can be extended and controlled with a simple double-lens setup. We derive a simple formula for the filamentation distance, and confirm its agreement with the experimental results. We also observe that delaying the onset of filamentation increases the filament length.

Control of the filamentation distance and pattern in long-range atmospheric propagation

We use the double-lens setup [10, 11] to achieve a 20-fold delay of the filamentation distance of non-chirped 120 fs pulses propagating in air, from 16m to 330m. At 330m, the collapsing pulse is sufficiently powerful to create plasma filaments. We also show that the scatter of the filaments at 330m can be significantly reduced by tilting the second lens. To the best of our knowledge, this is the longest distance reported in the Literature at which plasma filaments were created and controlled. Finally, we show that the peak power at the onset of collapse is significantly higher with the double-lens setup, compared with the standard negative chirping approach.

A plasma microlens for ultrashort high power lasers

We present a technique for generation of miniature plasma lens system that can be used for focusing and collimating a high intensity femtosecond laser pulse. The plasma lens was created by a nanosecond laser, which ablated a capillary entrance. The spatial configuration of the ablated plasma focused a high intensity femtosecond laser pulse. This configuration offers versatility in the plasma lens small f-number for extremely tight focusing of high power lasers with no damage threshold restrictions of regular optical components.

Boron nitride plasma micro lens for high intensity laser pre-pulse suppression.

We demonstrate that amplified spontaneous emission (ASE) and pre-pulses for high power lasers can be suppressed by propagating the pulse through a boron nitride plasma microlens. The microlens is created by ablating a boron-nitride (BN) disk with a central hole using an Nd:YAG laser . The plasma lens produced in the ablation process exhibits different focal lengths for the high intensity main pulse and low intensity pre-pulse that increases the main pulse/pre-pulse contrast ratio by one order of magnitude while maintaining high transmittance of the pulse energy.

INTERACTION OF INTENSE SHORT LASER PULSES WITH AIR AND DIELECTRIC MATERIALS

A study of the propagation of intense short laser pulses in air and the interaction of these pulses with distant targets is described. It is shown that the beam filamentation pattern can be controlled by introducing beam astigmatism. In addition, it is demonstrated that the collapse distance of intense femtosecond laser beams scales as P-1/2 for input powers that are moderately above the critical power for self focusing, and that at higher powers the collapse distance scales as P-1. Related to the interaction of intense short pulses with distant targets, it is measured that the threshold fluence for optical damage in wide gap materials is lower by up to 20% for negatively chirped pulses than for positively chirped, at pulse durations ranging from 60 fs to 1 ps.

Third harmonic generation by a low intensity laser pulse in a corrugated discharge capillary

Quasi phase matching and increase of laser interaction length were promoted by periodically modulated plasma guide formed by a discharge current ablating the inner capillary walls. The phenomenon was demonstrated through the use of third harmonics. For Ti:Sapphire laser pulses propagating through 1 cm long corrugated discharge capillaries, with an axial corrugation period of 200 μm, the third harmonic was generated at intensities as low as ∼109 W/cm2.

Control of the Filamentation Distance and Pattern in Long Range Atmospheric Propagation

Using a tilted double-lens setup we obtained highly-localized plasma filaments with 120fs pulses at a distance of 330m which, to the best of our knowledge, is the longest distance reported in the literature.