Table of Contents:
The microscopic equations of motion for THz light interacting with an electron hole plasma are presented.
This system is presumed to be incoherent and an analogy is made between the holes of the plasma and
the fixed positive ions at the heterojunction of a 2DEG system. An analytic solution to the system
response leads to the correct Lindhard type of response for three dimensional electron
gases interacting with a transverse THz field. This analysis also gives the
response for one- and two- dimensions,
which is not predicted by longitudinal plasma frequencies.
This transverse response is compared with a longitudinal dielectric
function which is often found in literature concerning the interaction of THz light with 2DEGs.
A comparison is made between the behaviour of the transversal response with electron density and the
behaviour of a longitudinal plasmon response with density.
A fully dynamic response is also computed, to examine
the temporal evolution of the ``transverse plasmon'' response.
This work clearly illustrates when and why a longitudinal plasmon
approach does not reproduce experimental results
concerning THz spectroscopy of electron gases,
a source of sizeable current interest in both
physics and nanotechnology communities.