  The optical properties of hybrid molecules composed of semiconductor and
metal nanoparticles with a weak probe in a strong pump field are investigated
theoretically. Excitons in such a hybrid molecule demonstrate novel optical
properties due to the coupling between exciton and plasmon. It is shown that a
non-absorption hole induced by coherent population oscillation appears at the
absorption spectrum of the probe field and there exists slow light effect
resulting in the great change of the refractive index. The numerical results
indicate that with the different center-to-center distance between the two
nanopaticles the slow light effects are greatly modified in terms of
exciton-plasmon couplings.
