Polarization and ellipticity of high-order harmonics from aligned molecules generated by linearly polarized intense laser pulses

Abstract

We present theoretical calculations for polarization and ellipticity of high-order harmonics from aligned N${}_2$, CO${}_2$, and O${}_2$ molecules generated by linearly polarized lasers. Within the rescattering model, the two polarization amplitudes of the harmonics are determined by the photo-recombination amplitudes for photons emitted parallel and perpendicular to the direction of the {\em same} returning electron wave packet. Our results show clear species-dependent polarization states, in excellent agreement with experiments. We further note that the measured polarization ellipse of the harmonic furnishes the needed parameters for a "complete" experiment in molecules.

4 pages, 4 figures