Optical coupling of quantum dots and silicon (Si) photonic-crystal cavities may be useful as novel optical integrated light emitters that can be erased and rewritten, say scientists in Italy and France. Doctoral student Silvia Vignolini and group leader Diederik Wirsma at the European Laboratory for Nonlinear Spectroscopy (Firenze, Italy) and colleagues developed the rewritable local source inside a Si-based, 635-nm-wide microcavity at the center of a honeycomb pattern injected with a microscopic drop of toluene containing a few thousand lead sulfide quantum dots (QDs).

The team used a scanning near-field optical microscope to direct 780 nm light into the cavity to excite the suspended quantum dots and also measure the photoluminescence emission. The cavity shape and size, with a predicted resonance mode at 1300 nm, influenced the QD emission to redistribute around a 2-nm-wide peak at 1315 nm and a broader band at 1257 nm. With further development of the cavity response to refractive-index variations, the microcavities could be useful as nanoscale detectors in silicon. Contact Silvia Vignolini at vignolini@lens.unifi.it.