Progress in developing nanophotonic integrated circuits

We review recent progress in the development of nanophotonic devices using the optical near-field interaction. ZnO nanocrystallites are potentially ideal components for realizing room-temperature operation of such devices due to their high exciton-binding energy and great oscillator strength. To confirm this promising optical property of ZnO, we examined the near-field time-resolved spectroscopy of ZnO nanorod double-quantum-well structures (DQWs). First, we observed the nutation of the population between the resonantly coupled exciton states of DQWs, in which the coupling strength of the near-field interaction was found to decrease exponentially as the separation increased. Furthermore, we successfully demonstrated the AND-gate operation by controlling a dipole-forbidden optical energy transfer among resonant exciton states. Our results provide criteria for designing nanophotonic devices. The success of time-resolved near-field spectroscopy of isolated DQWs described here is a promising step toward realizing a practical nanometerscale photonic switch and related devices.