Influence of Initial Pulse Chirp on Rainbow-Like Supercontinuum Generation from Filamentation in Air

Supercontinuum (SC) generation from laser filamentation in air is found
to depend strongly on the pulse duration. Rainbow-like SC generation is
observed only for a pulse of appropriate negative chirp that agrees
with the predictions put forward by Golubtsov it et al. it Quantum Electron. 33 (2003) 525. The conversion efficiency of an 800-nm laser light to rainbow-like SC is found to be the highest for 257fs pulses with an initial negative chirp. A larger chirp will lead to filamentation surviving at longer distance.