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The authors report on an experimental demonstration of coupling of quantum dots with a point-defect nanocavity in woodpile three-dimensional (3D) photonic crystal (PhC) with the highest quality (Q) factor among those for 3D PhC cavities. The Q factor of more than 8600 was achieved by stacking 25 layers using a micromanipulation technique. The size of the square-shaped defect cavity was optimized to tune the cavity mode to the midgap frequency of the complete photonic bandgap to achieve high Q.

We investigate the dependence of quality factor Q of dipole modes in photonic crystal H1-defect nanocavity on the slab thickness and observe an increase of Q even after closing of the photonic bandgap both in numerical simulation and experimentation. This counter intuitive behavior results from the weak coupling between the cavity mode and the 2nd-guided mode in the photonic crystal slab. This is confirmed by computing the overlap between them in the momentum space.

A novel technique for the fabrication of photonic crystal (PC) nanocavities coupled with colloidal nanocrystals is presented. A waveguiding resist membrane embedding highly emitting dot-in-a-rod nanocrystals was patterned through e-beam lithography and released through wet etching process. The proposed approach makes the PC structure independent of fabrication imperfections induced by etching steps. Micro-photoluminescence spectra revealed degenerated resonant modes (Q-factor approximately 700) whose fabrication-induced spectral splitting is comparable to the full width at half-maximum of the peaks. Active nanocavities tunable from visible to infrared spectral range on GaAs or Si substrates can be easily implemented by this technique.