On-off intermittency in an optically injected semiconductor laser.

We report on the observation of on-off intermittency in an optically injected dual-mode semiconductor laser. It is shown that quasi-single-mode chaotic dynamics of the injected mode are accompanied by intermittent and irregular bursts of the intensity of the uninjected mode. We define a threshold intensity of the uninjected mode to distinguish laminar and bursting states of the system. For small values of the threshold parameter we observe excellent agreement with the predictions of theory for the distribution of the laminar phase durations. For larger values of the threshold parameter, a gap appears in the distribution of laminar phase durations. Numerical simulations demonstrate that this gap is a consequence of the fact that in this case the on states of the system define large intensity spikes, which can belong either to the same or to distinct bursts away from the single-mode manifold.

High efficiency NbN nanowire superconducting single photon detectors fabricated on MgO substrates from a low temperature process.

We demonstrate high-performance nanowire superconducting single photon detectors (SSPDs) on bN thin films grown at a temperature compatible with monolithic integration. NbN films ranging from 150 nm to 3 nm in thickness were deposited by dc magnetron sputtering on MgO substrates at 400 degrees C SSPDs were fabricated on high quality NbN films of different thickness (7 to 3 nm) deposited under optimal conditions. Electrical and optical characterizations were performed on the SSPDs. The highest QE value measured at 4.2K is 20% at 1300 nm.