Terahertz nonlinear spectroscopy of free-carriers in direct bandgap semiconductors

Abstract

Nonlinear dynamics of free-carriers in direct bandgap semiconductors at terahertz (THz) frequencies is studied using intense few-cycle pulses. Techniques as Z-scan, THz-pump / THz-probe, and optical-pump/ THz-probe are employed to explore nonlinear interactions in both n-doped and photoexcited systems. The physical mechanism that gives rise to such interactions is found to be intervalley scattering.

Scheme to extend the range of electro-optic sampling of an intense terahertz field

“…Various schemes of experiments to increase the efficiency of THz generation have been reported recently [10,11]. The intense THz field can induce innovative phenomena such as ultrafast magnetization and an isolator-to-metal transition, and it can also be applied to the future study of nonlinear optics [12,13].…”