We demonstrate upconversion-assisted single-photon detection for the 1.55-μm telecommunications band based on a periodically poled lithium niobate (PPLN) waveguide pumped by a monolithic PPLN optical parametric oscillator. We achieve an internal conversion efficiency of 86%, which results in an overall system detection efficiency of 37%, with excess noise as low as 10(3) counts s(-1). We measure the dark count rate versus the upconversion pump-signal frequency separation and find the results to be consistent with noise photon generation by spontaneous anti-Stokes Raman scattering. These results enable detailed design guidelines for the development of low-noise quantum frequency conversion systems, which will be an important component of fiber-optic quantum networks.

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The efficiency of solvent extraction of bitumen from mined Athabasca oil sands has been studied in laboratory-scale, batch, stirred vessels. Solvent type, solids concentration, stirrer speed and contact time have been identified as important parameters. A theoretical analysis of the extraction process provides a basis by which the various parameters are assessed in terms of relative overall mass transfer coefficients. However, because the size distribution of the oil sand aggregates is difficult to reproduce, the analysis is limited. Greater reproducibility, and similar quantitative results were obtained for the dissolution of pure bitumen from the bottom of the stirred vessels.It is shown that highly aromatic solvents such as benzene and toluene can dissolve bitumen 3-5 times faster than an essentially alphatic solvent such as kerosene. There is evidence, however, which indicates that solvent properties other than aromaticity are also important.The data indicate that a minimum stirrer speed must be exceeded before the extraction of oil sand or pure bitumen will proceed at a reasonable rate. Above this minimum rate, the mass transfer coefficient increases linearly with stirrer speed. The solids concentration is also important since the data suggest that a higher efficiency is obtained at higher solids concentrations in the range of solid loadings studied. any schemes for the separation of bitumen from

We show that plane-wave singly resonant optical parametric oscillators exhibit a temporal modulation instability when pumped a certain number of times above threshold. Previously, this instability threshold was predicted, with a model neglecting variations in pump power, to occur at around 4.61 times oscillation threshold. We consider here the full self-consistent interaction between pump, signal, and idler sidebands and find that in some spectral regions the instability threshold can be lower than previously predicted, in some cases even comparable to the oscillation threshold, preventing single mode operation at high conversion efficiency. We examine the behavior of the instability for typical regions of operation, and find that both group velocity mismatches and group velocity dispersion have a significant effect. The instability can be suppressed by a suitable choice of intracavity etalon, the design constraints of which are determined.

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