Integrated photonic crystal networks with coupled quantum dots

Single InAs quantum dots can be used to control the transmission function of photonic crystal cavities, as we have already shown for systems that operate both in strong and weak coupling regime. Here we present our most recent work on devices where the cavity is connected in a micron-scale optical network via multiple photonic crystal waveguides terminated with input and output optical couplers. This architecture allows for multiple signal and control beams to be coupled simultaneously in the cavity via distinct ports. The devices are equipped with two input ports where the waveguides are terminated with input grating-couplers that allow for coupling into the waveguide from an out-of-plane direction. A third waveguide coupled to the cavity is terminated with a different kind of grating out-coupler that allows for improved directional scattering of the light transmitted through the cavity. We have already shown in previous experiments with a single cavity with coupled quantum dots, that this system acts as a highly nonlinear medium that enables all optical switching at powers down to the single photon level. In our most recent experiments we take significant steps towards demonstrating that this switching can be done in integrated structures, as needed for optical signal processing devices for both classical and quantum information science.