Abstract
Novel ultrafast coherent light sources open new opportunities for the probe and control of ultrafast dynamics and nonlinear optical responses in atoms, molecules and materials.
I will present work on developing table-top ultrafast light sources based on nonlinear frequency conversion of near-IR ultrafast lasers in two distant spectral regions. Towards long wavelengths, high power single-cycle and multi-cycle Terahertz (THz) light pulses are generated by non-collinearly phase-matched optical rectification in a LiNbO3 crystal. Towards short wavelengths, the extreme ultraviolet (EUV) and soft X-ray light pulses are produced by high-order harmonic processes in atomic gases.
Spectroscopy applications that take advantage of the ultrashort pulse durations or high electric field strength of these light sources will also be discussed. Ultrashort EUV light pulses make it possible to explore non-Born-Oppenheimer dynamics in EUV excited molecular ions in a time-resolved manner, revealing a natural competition between electron autoionization and nuclear predisscoiation. My current work explores the possibilities of using intense THz light to manipulate polarization dynamics in ferroelectric materials.
I will conclude my talk with an outlook of future directions I would like to pursue, including developing ultrafast table-top photon sources in both ultraviolet and THz spectral regions, and their applications in molecular and material physics, e.g. pump-probe and nonlinear molecular spectroscopy using ultraviolet pulses and material responses in extreme intense THz fields.
Coffee and tea will be served 20 minutes prior to the seminar.