Comparison study of supercontinuum generation by molecular alignment of N₂ and O₂

We study the supercontinuum generation through femtosecond filamentation by using the quantum wake of the prealigned diatomic molecules of O₂ and N₂, where significant ultraviolet extension of the generated supercontinuum is attributed to the additional cross-focusing effect around parallel revival of molecular alignment and the consequent self-steepening as well as space-time focusing effect. Due to the discrepancy of the polarizabilities between O2 and N2 molecules, the spectral ultraviolet extension of the generated supercontinuum is more noticeable in molecular O2 than that in N2, and an extended supercontinuum spectrum from 370 to 900 nm is observed in O₂ of 2 atm. The detailed dependence of the generated supercontinuum on the pump intensity for molecular alignment and gas pressure of O₂ and N₂ molecules are performed.