Optical Imaging of Coherent Molecular Rotors. Issue 5 (11th March 2020)

• Record Type: Journal Article
• Authors: Bert, Jérémy; Prost, Emilien; Tutunnikov, Ilia; Béjot, Pierre; Hertz, Edouard; Billard, Franck; Lavorel, Bruno; Steinitz, Uri; Averbukh, Ilya Sh.; Faucher, Olivier
• Is Part Of: Laser & photonics reviews. Volume 14:Issue 5(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-03-11
• Subjects: optical imaging -- spinning molecules -- ultrafast birefringence -- vortex half‐wave retarder; Lasers -- Periodicals; Photonics -- Periodicals; Lasers -- Périodiques; Photonique -- Périodiques; 621.36
• DOI: 10.1002/lpor.201900344
• Languages: English
• ISSNs: 1863-8880

Abstract

Abstract: Short laser pulses are widely used for controlling molecular rotational degrees of freedom and inducing molecular alignment, orientation, unidirectional rotation, and other types of coherent rotational motion. To follow the ultrafast rotational dynamics in real time, several techniques for producing molecular movies have been proposed based on the Coulomb explosion of rotating molecules, or recovering molecular orientation from the angular distribution of high harmonics. The present work offers and demonstrates a novel nondestructive optical method for direct visualization and recording of movies of coherent rotational dynamics in a molecular gas. The technique is based on imaging the time‐dependent polarization dynamics of a probe light propagating through a gas of coherently rotating molecules. The probe pulse continues through a radial polarizer, and is then recorded by a camera. The technique is illustrated by implementing it with two examples of time‐resolved rotational dynamics: alignment–antialignment cycles in a molecular gas excited by a single linearly polarized laser pulse, and unidirectional molecular rotation induced by a pulse with twisted polarization. This method may open new avenues in studies on fast chemical transformation phenomena and ultrafast molecular dynamics caused by strong laser fields of various complexities. Abstract : A new optical method for visualizing a fast rotational motion of coherently excited gas molecules is reported. The medium is illuminated by a circularly polarized short laser pulse and imaged by a homemade polarization‐sensitive detector. Snapshots are recorded with a time interval of a few tens of femtoseconds enabling recording a high‐resolution movie of the molecular rotational motion.