  In order to study the possible phase conjugation of optical near-fields, it
is necessary to go beyond the slowly varying envelope- and electric dipole
approximations that are normally applied in phase conjugation studies where
spatially non-decaying (or at least slowly decaying) modes are mixed. In the
present dissertation, the minimal coupling Hamiltonian is used to create a
microscopic theoretical description of degenerate four-wave mixing. It is a
semiclassical description where the electromagnetic field is treated as a
classical quantity and the active medium is treated quantum mechanically.
Numerical results are given for a single-level quantum well (exclusively
intraband contributions) and for a two-level quantum well (mainly interband
contribution). Focusing of a phase conjugated field is also discussed.
(Full-length abstracts in Danish and English included).
