Contributions of leading and tailing pulse edges to filamentation and supercontinuum generation of femtosecond pulses in air

Abstract

By simulating the filamentation of femtosecond laser pulses with flat top and different steep leading and tailing edges in air, the influence of pulse edges on the filamentation dynamics and supercontinuum (SC) generation is analyzed. It is found that the filamentation length is determined by the leading edge. The different roles of the pulse edges in the SC generation are further revealed. Under a relative lower laser power, the spectral broadening of the laser pulse originates mainly from the self-phase modulation of both pulse edges induced by the Kerr effect, while under a relative higher power condition, the leading edge plays a dominant role in the blue-side extension of the SC due to electron generation.

Spectral Hump Formation in Visible Region of Supercontinuum from Shaped Femtosecond Laser Filamentation in Fused Silica

“…The self-phase modulation (SPM) is regarded as the main mechanism causing the spectral broadening of the intense femtosecond laser pulse. Our previous studies revealed that the pulse shape plays a dominant role in the filamentation and SC generation due to the SPM and electron generation [38,39]. More complicated pulse shapes will induce steeper ascending and descending edges in the laser pulse, which can lead stronger blueside spectral extension [39].…”

High power supercontinuum generation by dual-color femtosecond laser pulses in fused silica

“…[1] Nonlinear processes that participate simultaneously in filamentation and SC generation are considered as self-phase modulation, [2] selfsteepening, [3,4] and plasma formation. [5] The broadband spectral characteristics of the SC stimulate many potentials in various research fields and applications, such as gas sensing, [6,7] electronic spectroscopy, [8] cavity ring-down spectroscopy, [9] and few-cycle femtosecond pulses generation. [8,10] High spectral power of SC is one of the critical requirements of many applications such as absorption spectroscopy and oxygen saturation mapping from optical coherence tomography.…”

Powerful supercontinuum vortices generated by femtosecond vortex beams with thin plates

“…When intense femtosecond laser pulses propagate in Kerr medium, supercontinuum emission are mainly generated by self-phase modulation(SPM) [15] and self-steepening effects [16]. When filamentation occurs, ionization also plays an important role in the blue shift of spectrum broadening [17]. However, the supercontinuum will lose the vortex phase profile if multiple filaments are generated [10,18].…”