Polariton-induced optical asymmetry in the reflectivity spectra of coupled
semiconductor microcavity structures, containing quantum wells in one of th
e cavities, is reported. The central mode of the system is only observable
when viewed from one side of the structure, but is dark and invisible from
the other side. At the same time, all other spectral features are the same
from both sides of the structure. Microscopically, interference between the
exciton and cavity modes is shown to lead to the optical asymmetry. Furthe
rmore, the asymmetric exciton-cavity mode is observable only for light inci
dent on the cavity without excitons, a result shown to be fully consistent
with a coupled oscillator model. [S0163-1829(98)02247-4].