Elliptical attosecond pulses generated from mixed atomic gases in corotating bicircular laser fields

Abstract

We propose a scheme for generating bright elliptically polarized attosecond pulses from mixed Ne–He gases driven by a $\omega -4\omega$ corotating bicircular field with a high optical chirality. We find that the harmonic spectra from the pure p-type states of Ne atoms in this corotating bicircular field possess a high chirality, and the harmonic intensity can be comparable to those in a $\omega -2\omega$ counterrotating bicircular field by increasing the intensity ratio. Moreover, since the interference between harmonics from mixed gases has different effects on right- and left-handed components of the adjacent harmonics, the spectra with large intensity difference in a wide energy region can be obtained. Simultaneously, constructive interference between every allowed harmonic from different gas targets leads to the enhancement of the harmonic intensity. Therefore, our results demonstrate that one can optimize the attosecond pulses in terms of ellipticity and intensity by using mixed atomic gases in the corotating bicircular field.