  In recent experiments on coupled quantum dot (QD) optical cavity systems a
pronounced interaction between the dot and the cavity has been observed even
for detunings of many cavity linewidths. This interaction has been attributed
to an incoherent phonon-mediated scattering process and is absent in atomic
systems. Here, we demonstrate that despite its incoherent nature, this process
preserves the signatures of coherent interaction between a QD and a strong
driving laser, which may be observed via the optical emission from the
off-resonant cavity. Under bichromatic driving of the QD, the cavity emission
exhibits spectral features consistent with optical dressing of the QD
transition. In addition to revealing new aspects of the off-resonant QD-cavity
interaction, this result provides a new, simpler means of coherently probing
QDs than traditional approaches and opens the possibility of employing
off-resonant cavities to optically interface QD-nodes in quantum networks.
