Nonlinear Optical Effects with Polariton Lasers in a GaAs Microcavity*

We report the nonlinear optical properties of polaritons in a single quantum well GaAs
microcavity. Single and double resonance cavities have been used to enhance the nonlinear effect of a
nonlinear medium in high-Q quality factor cavities due to the cavity field amplification. On the other hand, such
a cavity can generate polaritons, which condense (Bose− Einstein condensation) for determined conditions,
such as cavity detuning and polariton density. Here, we present experimental observations of the second
harmonic generation from polaritons in a GaAs microcavity, which exhibit a 2 order higher efficiency than those
from the usual method. Furthermore, the efficiency is particularly high when the polariton is a photon-like
particle and in a condensed state.