  We observe the weak coupling of lead sulphide nanocrystals to localized
defect modes of 2-dimensional silicon nanocavities. Cavity resonances
characterized with ensemble nanocrystals are verified with cold-cavity
measurements using integrated waveguides. Polarization dependence of the cavity
field modes is observed. The linewidths measured in coupling experiments are
broadened in comparison to the cold-cavity characterization, partly due to
large homogeneous linewidths of the nanocrystals. The calculated Purcell factor
for a single exciton is 75, showing promise toward applications in single
photon systems. These novel light sources operate near 1.55 micron wavelengths
at room temperature, permitting integration with current fiber communications
networks.
