Weak coupling interactions of colloidal lead sulphide nanocrystals with silicon photonic crystal nanocavities near 1.55 μm at room temperature

The authors observe the weak coupling of lead sulphide nanocrystals to localized defect modes of two-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 [Phys. Rev. 69, 681 (1946)] for a single exciton is 100, showing promise toward applications in single photon systems. These novel light sources operate near 1.55 μm wavelengths at room temperature, permitting integration with current fiber communication networks.