Weak coupling interactions of colloidal lead sulphide nanocrystals with   silicon photonic crystal nanocavities near 1.55 microns at room temperature
  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. 
Ranojoy Bose, Xiaodong Yang, Rohit Chatterjee, Jie Gao and Chee Wei   Wong