Abstract
We simulate the coherent carrier dynamics of an optically excited, undoped AlGaAs superlattice in the presence of a terahertz pulse using an excitonic formalism that includes excitonic states as well as higher in-plane excited states and allows for dephasing and population decay. We show that this system exhibits tunable terahertz gain due to excitonic effects, even in the presence of a large number of unbound excitons. We find that gain coefficients greater than can be achieved over a tuning range of and that due to the coherent cascading of the carriers down the excitonic Wannier-Stark ladder, the gain coefficients have much higher gain saturation fields than comparable two-level systems.
1 More- Received 2 November 2007
DOI:https://doi.org/10.1103/PhysRevB.77.115307
©2008 American Physical Society