"Below gap optical absorption in GaAs driven by intense, single-cycle coherent transition radiation"

J. Goodfellow: M. Fuchs, D. Daranciang, S. Ghimire, F. Chen, H. Loos, D. A. Reis, A. S. Fisher, and A. M. Lindenberg; Optics Express, 07/10/14.

Additional Authors: M. Fuchs, D. Daranciang, S. Ghimire, F. Chen, H. Loos, D. A. Reis, A. S. Fisher, and A. M. Lindenberg

Abstract:

Single-cycle terahertz fields generated by coherent transition radiation from a relativistic electron beam are used to study the high field optical response of single crystal GaAs. Large amplitude changes in the sub-band-gap optical absorption are induced and probed dynamically by measuring the absorption of a broad-band optical beam generated by transition radiation from the same electron bunch, providing an absolutely synchronized pump and probe geometry. This modification of the optical properties is consistent with strong-field-induced electroabsorption. These processes are pertinent to a wide range of nonlinear terahertz-driven light-matter interactions anticipated at accelerator-based sources.