Third-harmonic generation in coherently spinning molecules

Dr. Emilien Prost


Over the paste decade several ways to bring gas phase molecules to a coherent rotational motion have been developed, leading to several studies on the features of coherently spinning molecules in the realm of linear optics. One of the features they exhibit is the rotational Doppler effect, coming from the exchange of angular momentum between the optical field and the molecules. Using energy and angular momentum conservation based arguments one can show that the rotational Doppler shift is directly proportional to the rotational frequency of the spinning object. This makes coherently spinning molecules a great medium to obtain shift in the THz domain, thanks to the rotational frequency of gas phase molecules. Here, I will present an extension of this work to the field of nonlinear optics via third-harmonic generation by a circularly polarized field in coherently spinning molecules. Using the same arguments and conservation laws as above, one can show that four frequency shifts are possible for the emitted harmonics. I will show the four different measured spectral shifts and then a study of the influence of different parameters on the generated harmonics.


GAP, Département de physique Appliquée
22 ch. de Pinchat, 1227 Carouge
Seminar room 3