Observations of the Biology of \u3ci\u3ePhasgonophora Sulcata\u3c/i\u3e (Hymenoptera: Chalcididae), a Larval Parasitoid of the Twolined Chestnut Borer, \u3ci\u3eAgrilus Bilineatus\u3c/i\u3e (Coleoptera: Buprestidae), in Wisconsin

Phasgorzophora sulcata Westwood was the principal larval parasitoid of Agrilus bilineatus (Weber) during a study conducted in a natural oak-hardwood forest in the Kettle Moraine State Forest, Jefferson County, Wisconsin. Mean percent larval parasitism was 10.5%. Mean A. bilineatus and P. sulcata densities were, respectively, 53.0 and 6.1 adults per square meter of bark. The theoretical developmental threshold temperatures for over- wintering A. bilineatus and P. sulcata larvae were 17.8 and 19.l0C, respectively. The peak flight period of P. sulcata (9 July 1980) occurred ca. 3 weeks after the A. bilineatus peak flight (18 June 1980) at about the time of peak A. bilineatus egg eclosion. The P. sulcata sex ratios (malexfemales) for laboratory-reared and field-captured adults were 1:1.35 and 1:3.22, respectively

A circular dielectric grating for vertical extraction of single quantum dot emission

We demonstrate a nanostructure composed of partially etched annular trenches in a suspended GaAs membrane, designed for efficient and moderately broadband (approx. 5 nm) emission extraction from single InAs quantum dots. Simulations indicate that a dipole embedded in the nanostructure center radiates upwards into free space with a nearly Gaussian far-field, allowing a collection efficiency > 80 % with a high numerical aperture (NA=0.7) optic, and with 12X Purcell radiative rate enhancement. Fabricated devices exhibit an approx. 10 % photon collection efficiency with a NA=0.42 objective, a 20X improvement over quantum dots in unpatterned GaAs. A fourfold exciton lifetime reduction indicates moderate Purcell enhancement.Comment: (3 pages

Efficient quantum dot single photon extraction into an optical fiber using a nanophotonic directional coupler

We demonstrate a spectrally broadband and effcient technique for collecting photoluminescence from a single InAs quantum dot directly into a standard single mode optical fiber. In this approach, an optical fiber taper waveguide is placed in contact with a suspended GaAs nanophotonic waveguide with embedded quantum dots, forming an effcient and broadband directional coupler with standard optical fiber input and output. Effcient photoluminescence collection over a wavelength range of tens of nanometers is demonstrated, and a maximum collection effciency of 6.05 % (corresponding single photon rate of 3.0 MHz) into a single mode optical fiber was estimated for a single quantum dot exciton

Correlations Beyond the Nearest-Neighbor Level in Grain Boundary Networks

Correlations among \u27special\u27 and \u27general\u27 grain boundaries are studied on two-dimensional networks, by examining the configurational entropy of boundary structures as well as percolation thresholds. Consideration of crystallographic constraints at various length scales reveals that higher-order constraints play a role in boundary connectivity and network structure. Implications for grain boundary engineering are discussed and directions for future work highlighted