Nonlinear transport and Terahertz generation in two-dimensional systems under strong optical irradiation
Simon Huppert (LPA)

Abstract

This thesis treats of nonlinear behaviors in two types of bidimensional
systems : semiconductor heterostructures as well as a monolayer material,
graphene. It consists into two parts : the modelling of new effects for
electromagnetic wave generation in the Terahertz range and the study
Wannier-Stark quantification in quantum well superlattices.

We study quantitatively two nonlinear effects recently proposed for
Terahertz generation. The first one is Terahertz emission exaltation in a
polaritonic system reaching the polariton lasing regime. We model this
effect and suggest a new scheme using a double microcavity and providing
significant reduction of the diffusion losses. The second effect is
dynamic photon drag in graphene under pulsed excitation. We present a
microscopic and predictive model for this phenomenon which provides a
comprehensive insight on the relevant parameters for the optimisation of
the Terahertz generation.

In quantum well superlattices under an external voltage, the electric
field induces bidimensional confinement of the charge carriers, this
effect is known as Wannier-Stark quantification. We examine two
interesting consequences of this confinement : the strong photocurrent
nonlinearities induced when the superlattice is placed between thick
tunnel barriers, and the possibility to control light-matter coupling as
well as Terahertz gain in superlattices coupled to a semiconductor
microcavity.