Abstract

Circularly polarized molecular high order harmonic generation, MHOHG, as source for circularly polarized attosecond pulses is modelled by numerical solution of the 3-D one electron H2+ time-dependent Schroedinger equation, TDSE, in the nonlinear nonperturbative regime of molecule laser interaction[1].It is shown that the nonsymmetric molecular Coulomb potential is essential for producing circularly polarized MHOHG by few cycle intense circularly polarized IR pulses(800 or 400 nm).An intense teraherz, Thz, (4um) pulse is added to control and force recollision of the ionized electron with the parent ion,thus enhancing the efficiency of the circularly polarized MHOHG process which is absent in atoms.The phases of the x,y components of the electric field of each harmonic are shown to differ exactly by pi/2, thus confirming the circular polarization. Furthermore a Gabor wavelet time-frequency analysis shows that the harmonics are created by single recollision of the ionized electron with the parent ion[2], as opposed to the standard double recollision (short and long trajectories) model of HHG.Superposition of the circularly polarized harmonics allows for the synthesis of circularly polarized pulses of duration of ~ 100 attoseconds. Such new ultrashort pulses should allow fot the control of electrons on their natural time scale, the attosecond = 10**−18s. In particular it will be shown that such new pulses are important tools for creating attosecond electronic currents inside molecules thus generating attosecond magnetic field pulses of intensity ~ 10–100 Teslas inside matter.

© 2013 IEEE