The PFL team of the ICB laboratory on the cover of the scientific review “Laser & Photonics Reviews”

The article « Optical Imaging of Coherent Molecular Rotors » from the PFL team (Femtosecond Processes and Intense Laser) of the Photonics department has been selected for the cover of issue 14 – May 2020 of Laser & Photonics Reviews.

In its publication, the research team presents a new non-destructive optical method for visualizing rapidly rotating molecules in the gas phase. This work is part of the research carried out on the production and characterization of UDR (Unidirectional coherent rotation) by ultra-short laser pulses shaped, the generation of harmonic waves and circular waves in molecules. aligned by laser and producing rotational echoes.

The researchers studied the different strategies for optimizing unidirectional rotation and thus developed the tools necessary for its characterization.

The technique is based on the detection of the time-resolved birefringence of a laser-excited molecular gas. It allows you to record images similar to the one shown on the cover. A sequence of these images is combined into a high-resolution molecular film providing information on molecular orientation with a resolution of a few tens of femtoseconds.

The method used is illustrated by two examples of ultra-fast rotational dynamics:

• Alignment-anti-alignment cycles in a gas of molecules aligned by a linearly polarized laser pulse,
• Unidirectional molecular rotation induced by a rotating laser pulse.

This method could open new avenues in studies on the phenomena of rapid chemical transformation and the ultra-rapid molecular dynamics of molecules subjected to laser fields of various complexities.

• For more information : Jérémy Bert, Emilien Prost, Ilia Tutunnikov, Pierre Béjot, Edouard Hertz, Franck Billard, Bruno Lavorel, Uri Steinitz, Ilya Sh. Averbukh, and Olivier Faucher, Optical Imaging of Coherent Molecular Rotors, Laser & Photonics Review (2020)