799 research outputs found

    High-Speed High Effiency Large Area Resonant Cavity Enhanced p-I-n Photodiodes for Multimode Fiber Communications

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    Cataloged from PDF version of article.In this letter, we report AlGaAs–GaAs p-i-n photodiodes with a 3-dB bandwidth in excess of 10 GHz for devices as large as 60- m diameter. Resonant cavity enhanced photodetection is employed to improve quantum efficiency, resulting in more than 90% peak quantum efficiency at 850 nm

    High bandwidth-efficiency resonant cavity enhanced Schottky photodiodes for 800-850 nm wavelength operation

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    Cataloged from PDF version of article.High-speed resonant cavity enhanced Schottky photodiodes operating in 800-850 nm wavelength region are demonstrated. The devices are fabricated in the AlGaAs/GaAs material system. The Schottky contact is a semitransparent Au film which also serves as the top reflector of the Fabry-Perot cavity. The detectors exhibit a peak quantum efficiency of eta = 0.5 at lambda = 827 nm wavelength and a 3 dB bandwidth of more than 50 GHz resulting in a bandwidth-efficiency product of more than 25 GHz. (C) 1998 American Institute of Physic

    High-speed >90% quantum-efficiency p–i–n photodiodes with a resonance wavelength adjustable in the 795–835 nm range

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    Cataloged from PDF version of article.We report GaAs/AlGaAs-based high-speed, high-efficiency, resonant cavity enhanced p–i–nphotodiodes. The devices were fabricated by using a microwave-compatible fabrication process. By using a postprocess recess etch, we tuned the resonance wavelength from 835 to 795 nm while keeping the peak efficiencies above 90%. The maximum quantum efficiency was 92% at a resonance wavelength of 823 nm. The photodiode had an experimental setup-limited temporal response of 12 ps. When the system response is deconvolved, the 3 dB bandwidth corresponds to 50 GHz, which is in good agreement with our theoretical calculations. © 1999 American Institute of Physic

    Interfaces in the returnees' heritage language: Is the complete (re-)activation possible?

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    Aims and objectives/purpose/research questions: The aim of this study is to examine whether the complete (re-)activation of interface domains in the heritage language (HL) is possible or whether interfaces are likely to preserve features typical for the HL even after many years of residing in the country of origin. Design/methodology/approach: We present the group analysis of direct object marking in Turkish, which is a morphology-syntax-pragmatics interface, of Turkish-German returnees, who returned to Turkey after puberty and have been residing in the country for a minimum of 10 and a maximum of 34 years, and compare them with the control group consisting of Turkish speakers who have been living in Turkey all their lives. Data and analysis: The data were collected using a narrative task, a completion task and a grammaticality judgement task, and analysed both quantitatively and qualitatively. Findings/conclusions: The analysis of the narrative task revealed that the returnee participants used case-marking on direct objects productively depending on the discourse and syntactic position of the direct object in their heritage Turkish. However, their performance on the completion and grammaticality judgement tasks diverged from those of the control group. These findings can be considered as a piece of evidence that interface domains stay obstinate to complete (re-)activation and may preserve features typical for the HL many years after the return to the country of origin. Originality: The study suggests relevance of the Interface Hypothesis to the process of HL (re-)activation. Significance/implications: The study contributes to the research on the HL development of returnees after their return to the country of origin

    Natural occurrence of Cucumber mosaic virus infecting water mint (Mentha aquatica) in Antalya and Konya, Turkey

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    A virus causing a disease in mint (the aromatic and culinary plant) has recently become a problem in the Taurus Mountains, a mountain range in the Mediterranean region of Turkey. To detect the virus and investigate its distribution in the region, mint leaf samples were collected from the vicinity of spring areas in the plateaus of Antalya and Konya in 2009. It was found that Cucumber mosaic virus (CMV) was detected in 27.08% of symptomatic samples tested by DAS-ELISA. To the best of our knowledge, this is the first report of CMV on mint plants in this region of Turkey

    Deformable Model for 3D Intramodal Nonrigid Breast Image Registration with Fiducial Skin Markers

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    We implemented a new approach to intramodal non-rigid 3D breast image registration. Our method uses fiducial skin markers (FSM) placed on the breast surface. After determining the displacements of FSM, finite element method (FEM) is used to distribute the markers’ displacements linearly over the entire breast volume using the analogy between the orthogonal components of the displacement field and a steady state heat transfer (SSHT). It is valid because the displacement field in x, y and z direction and a SSHT problem can both be modeled using LaPlace’s equation and the displacements are analogous to temperature differences in SSHT. It can be solved via standard heat conduction FEM software with arbitrary conductivity of surface elements significantly higher than that of volume elements. After determining the displacements of the mesh nodes over the entire breast volume, moving breast volume is registered to target breast volume using an image warping algorithm. Very good quality of the registration was obtained. Following similarity measurements were estimated: Normalized Mutual Information (NMI), Normalized Correlation Coefficient (NCC) and Sum of Absolute Valued Differences (SAVD). We also compared our method with rigid registration technique
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