Speaker
Description
In the 1980s, femtosecond ultrafast lasers enabled optical generation of electric fields at terahertz frequencies. With the recent progress in few-optical-cycle femtosecond and attosecond pulse generation with full electric field control, the frequency regime can be extended into the petahertz. The electron motion under the influence of such a high-frequency electric field ultimately determines the material limit for high-speed device performance. We have started to explore materials in a regime where the quiver energy (or ponderomotive energy Up) of the electrons in such an oscillating electrical field becomes comparable to the photon energy of the driving laser. The system transitions from a more classical (field driven) regime to a more quantum-mechanical (photon driven) regime and we explored these regimes in diamond and GaAs. We also explored how long it takes for an excited electron in a metal to “feel” its effective mass and discovered new electron-localization effects in transition metals. The long-term goal is to explore such electric-field-driven dynamics in strongly correlated materials where we have even less physical understanding today.
