We have recently demonstrated a number of functional photonic crystals devices and circuits, including an ultrafast, room-temperature, low threshold, nanocavity laser with the direct modulation speed approaching 1THz, an all-optical switch controlled with 60 0 pulses and with the speed exceeding 20GHz, and a local, reversible tuning of individual quantum dots on a photonic crystal chip by up to 1.8nm, which was then used to tune single quantum dots into strong coupling with a photonic crystal cavity and to achieve a giant optical nonlinearity.