Ultrabroadband Terahertz Spectroscopy of Semiconductor Nanostructures

The terahertz (THz) electromagnetic wave frequency range - broadly defined as 0.1 – 30 THz (3 mm – 10 µm wavelength) - is at the interface of modern electronics and optics. This electromagnetic spectrum has been much less explored and has been called the “terahertz gap” due to the lack of efficient, room-temperature sources and detectors. Despite these difficulties, there has been recent explosion of interest in using THz pulse to address many questions in electrical engineering, physics, chemistry, and material sciences.
In this talk, I will discuss how ultrashort THz pulse from femtosecond (1 fs = 10^-15 s) solid-state laser sources can be generated and detected, and further used to investigate dynamical or localized conduction processes in semiconductor nanostructures. By measuring both amplitude and phase of the multi-THz waves, one can directly access the conductivity information of the nanostructures with sub-cycle temporal resolution.