Echo phenomena observed in an ensemble of laser-aligned molecules

Group of Femtosecond Processes & intense Laser (PFL)
Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), UMR 6303 CNRS-Université Bourgogne Franche-Comté, DIJON, FRANCE

In 2015 we have reported on one of the simplest classical systems featuring the echo phenomenon—a collection of randomly oriented free rotors with dispersed rotational velocities. Following excitation by a pair of time-delayed impulsive kicks, the mean alignment of the ensemble exhibits multiple echoes and fractional echoes. We have elucidated the mechanism of the echo formation by the kick-induced filamentation of phase space, and provided the first experimental demonstration of classical alignment echoes in a thermal gas of CO2 molecules excited by a pair of femtosecond laser pulses [1].


This study has been achieved in collaboration with the Université Paris Est Créteil and the Weizmann Institute of Science in Israel.
[1] G. Karras, E. Hertz, F. Billard, B. Lavorel, J.M. Hartmann, O. Faucher, E. Gershnabel, Y. Prior, I.S. Averbukh, Orientation and Alignment Echoes, Phys. Rev. Lett., 114  153601 (2015).

Olivier Faucher (53 years-old, male) is full Professor at the Physics Department of the Université Bourgogne Franche-Comté. He is the head of one of the leading groups with a research activity on laser-induced field-free molecular alignment. He has a strong expertise in research topics related to experimental studies of atoms and molecules exposed to ultra short and intense laser pulses.