Time-Resolved Terahertz Spectroscopy of Free Carrier Nonlinear Dynamics in Semiconductors

• Main Authors: G. Sharma, L. Razzari, F. H. Su, F. Blanchard, A. Ayesheshim, T. L. Cocker, L. V. Titova, H. C. Bandulet, T. Ozaki, J.-C. Kieffer, R. Morandotti, M. Reid, F. A. Hegmann
• Format: Article
• Language: English
• Published: IEEE 2010-01-01
• Series: IEEE Photonics Journal
• Subjects: Intervalley scattering; semiconductors; terahertz pulses; time-resolved terahertz spectroscopy; ultrafast nonlinear optics; z-scan
• Online Access: https://ieeexplore.ieee.org/document/5467198/
• ISSN: 1943-0655

Nonlinear dynamics of free carriers in direct bandgap semiconductors at terahertz (THz) frequencies is studied using the intense few-cycle source available at the Advanced Laser Light Source (ALLS). Techniques such as Z-scan and optical-pump/THz-probe are employed to explore nonlinear interactions in an n-doped InGaAs thin film and a photoexcited GaAs sample, respectively. The physical mechanism that gives rise to such interactions is found to be intervalley scattering. A simple Drude-based mathematical model that incorporates the intervalley scattering process is developed and agrees well with the THz response of free carriers in semiconductors.