Whispering gallery mode emission at telecommunications-window wavelengths using PbSe nanocrystals attached to photonic beads

We report the selective chemical attachment of infrared emitting PbSe nanocrystal quantum dots onto micron-scale glass photonic beads. Upon optical excitation, photoluminescence from the shell of nanocrystals is seen to couple into the high-Q 'whispering gallery' modes of the bead via the evanescent optical field, resulting in a series of sharp peaks being observed at wavelengths of around 1550 nm. Theoretical modelling gives a close agreement with the data for angular modes corresponding to l ∼ 120. This work demonstrates the potential of narrow-bandgap II-VI semiconductor nanocrystals for use in a wide range of telecommunications-window photonics applications.