All-optical switching using nonlinear subwavelength Mach-Zehnder on silicon

We report on the experimental demonstration of ultrafast all-optical switching and wavelength down-conversion based on a novel nonlinear Mach-Zehnder interferometer with subwavelength grating and wire waveguides. Unlike other periodic waveguides such as line-defects in a 2D photonic crystal lattice, a subwavelength grating waveguide confines the light as a conventional index-guided structure and does not exhibit optically resonant behaviour. Since the device had no dedicated port to input optical signal to control switching a new approach was also implemented for all-optical switching control

Invisible death rites in the early Neolithic: results of archaeothanatological analysis of Linearbandkeramik funerary practices from settlements

This poster presents the results of an archaeothanatological study of early Neolithic burials belonging to the Linearbandkeramik (LBK) culture (c. 5600-5000 cal BC). The dataset comprised 56 burials, from the settlements of Balatonszárszó, Hungary, and Vráble, Slovakia. Using high quality photographs from excavations, archaeothanatology was used to identify and categorise mortuary practice. The focus of this project was to identify evidence for diversity and intimacy in the treatment of the ..

Social and genetic diversity in first farmers of central Europe

The Linearbandkeramik (LBK) Neolithic communities were the first to spread farming across large parts of Europe. We report genome-wide data for 250 individuals: 178 individuals from whole-cemetery surveys of the Alföld Linearbankeramik Culture eastern LBK site of Polgár-Ferenci-hát, the western LBK site of Nitra Horné Krškany and the western LBK settlement and massacre site of Asparn-Schletz, as well as 48 LBK individuals from 16 other sites and 24 earlier Körös and Starčevo individuals from 17 more sites. Here we show a systematically higher percentage of western hunter-gatherer ancestry in eastern than in western LBK sites, showing that these two distinct LBK groups had different genetic trajectories. We find evidence for patrilocality, with more structure across sites in the male than in the female lines and a higher rate of within-site relatives for males. At Asparn-Schletz we find almost no relatives, showing that the massacred individuals were from a large population, not a small community

Ultra-fast all optical signal processing for advanced data communication

This paper looks at ultra-fast all optical signal processing for advanced data communicatio

P-ed-XRF-geochemical signatures of a 7300 year old Linear Band Pottery house ditch fill at Vráble-Ve'lké Lehemby, Slovakia - House inhabitation and post-depositional processes

Over the past decades multi-element analyses have become increasingly important for archaeological and geoarchaeological research. In particular the recent expansion in availability of portable ed-XRF (p-ed-XRF) devices has allowed for the fast acquisition of large data sets. In the presented paper, we evaluate the quantitative measurement capability of a p-ed-XRF device through comparison with wd-XRF. Sampling, drying, and homogenization (sieving < 2 and pulverizing) ensured comparable measurement conditions. The application of He-flotation in the measurement chamber and measurement times of a sufficient duration at low voltage/high amperage conditions increased measurement sensitivity for lighter elements (here at least 90 s at 6 kV, 100 μA), resulting in measurements of a satisfactory quality. In a case study, we measured the elemental contents of the archaeo-sediment-sequence fill of a trench of a ca. 7300 year old Linear Pottery house at the site of Vráble-Ve'lke Lehemby, in southeastern -Slovakia. Based on a model applied at the nearby Bronze Age settlement mound of Fidvár, the P content of the archaeo-sediment was considered as a proxy of palaeo-demography. However, the measured P contents were much too small to reflect the metabolism of a reasonable number of inhabitants. Therefore, in addition to the possibilities of shorter than expected duration of house occupation and incomplete garbage deposition within the ditches, the post-depositional settlement history is considered in detail. Furthermore, bio-cycling by plants during different subsequent phases of Holocene landscape development (forested, agricultural field use) has not been considered extensively in interpretations of the archaeological record so far, but might have had a considerable influence on the shallow buried archaeological record. A reconsideration of the interpretation of the geochemical record from a nearby Bronze Age site (Fidvár) is thus suggested

Possibilities of Bragg filtering structures based on subwavelength grating guiding mechanism (Conference Presentation)

Silicon-on-insulator (SOI), as the most promising platform, for advanced photonic integrated structures, employs a high refractive index contrast between the silicon \u201ccore\u201d and surrounding media. One of the recent new ideas within this field is based on the alternative formation of the subwavelength sized (quasi)periodic structures, manifesting as an effective medium with respect to propagating light. Such structures relay on Bloch wave propagation concept, in contrast to standard index guiding mechanism. Soon after the invention of such subwavelength grating (SWG) waveguides, the scientists concentrated on various functional elements such as couplers, crossings, mode transformers, convertors, MMI couplers, polarization converters, resonators, Bragg filters, and others. Our contribution is devoted to a detailed numerical analysis and design considerations of Bragg filtering structures based on SWG idea. Based on our previous studies where we have shown impossibility of application of various 2 and \u201c2.5\u201d dimensional methods for the proper numerical analysis, here we effectively use two independent but similar in-house approaches based on 3D Fourier modal methods, namely aperiodic rigorous coupled wave analysis (aRCWA) and bidirectional expansion and propagation method based on Fourier series (BEX) tools. As it was recently demonstrated, SWG Bragg filters are feasible. Based on this idea, we propose, simulate, and optimize spectral characteristics of such filters. In particular, we have investigated several possibilities of modifications of original SWG waveguides towards the Bragg filtering, including firstly - simple single-segment changes in position, thickness, and width, and secondly - several types of Si inclusions, in terms of perturbed width and thickness (and their combinations). The leading idea was to obtain required (e.g. sufficiently narrow) spectral characteristic while keeping the minimum size of Si features large enough. We have found that the second approach with the single element perturbations can provide promising designs. Furthermore, even more complex filtering SWG structures can be considered.Peer reviewed: YesNRC publication: Ye