Nonlinear ultrafast modulation of the optical absorption of intense few-cycle terahertz pulses in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>n</mml:mi></mml:math>-doped semiconductors

Abstract

We use an open-aperture $Z$ scan technique to show how intense few-cycle terahertz pulses can experience a nonlinear bleaching of absorption in an $n$-doped semiconductor due to terahertz-electric-field-driven intervalley scattering of electrons in the conduction band. Coherent detection of the transmitted terahertz pulse wave form also allows the nonlinear conductivity dynamics to be followed with subpicosecond time resolution. Both the $Z$ scan and time-domain results are found to be in agreement with our theoretical analysis.