Interference effects in harmonic ellipticity from H 2+ molecules in an orthogonally polarized two-color laser field

Abstract

We theoretically investigate the elliptically polarized harmonics from aligned molecular ion H2+ in orthogonally polarized two-color (OTC) laser pulses. Our results show that a striking peak appears in the ellipticity curve of odd-order harmonics, and this peak shows obvious alignment dependence and shifts toward higher energy as the amplitude ratio of two colors increases. The location of the peak is close to that of the interference minimum predicted by using a modified model of dipole, indicating strong two-center interference effects in ellipticity. Through adjusting the frequency ratio of two colors, large ellipticity is obtained for both odd and even harmonics in a wide energy region. As a result, we synthesize a bright elliptically polarized isolated attosecond pulse with an ellipticity up to 0.63.

Generating attosecond pulses with controllable polarization from cyclic H32+ molecules by bichromatic circular fields

“…From the inset, we can see that there are three attosecond bursts in one optical cycle, and the duration of the most intense burst is 107 as, which is shorter than the one up to 213 as long we obtained from H + 2 molecules under an OTC field. [38] APT with e = 0.56 is obtained and the duration of the most intense burst is 214 as. Our simulations show the viability of extending the BCCP scheme to molecule targets, and the control of the harmonic chirality inherently allows one to manipulate the polarization of the generating APTs.…”