Highly-efficient grating couplers based on transfer-printing technology

We propose a new approach that allows highly efficient fiber-to-chip coupling using transfer-printing technology. The novelty of the approach relies on the integration of a mirror between a top (source) grating coupler circuit and a bottom (target) photonic integrated circuit (PIC) and on a wide directional coupler to transfer the light between the two waveguide layers before tapering the waveguide to single mode widths. We propose an apodized, partially etched, grating coupler integrated with a directional coupler implemented in amorphous Si, while a crystalline 220nm Silicon-on-Insulator (SOI) platform is used for the target PIC. We achieve a simulated 2D coupling efficiency of 96.2% (-0.17 dB) with a 1 dB bandwidth of 45 nm. The bandwidth takes into account the broadband directional coupler, which is very compact. The alignment tolerance along the direction orthogonal to the light propagation is better than +/- 2 μm to achieve an insertion loss penalty lower than 1 dB, which is well within reach with transfer printing

Broadband digital tourier transform spectrometer for on-chip wavelength monitoring in the 2.3 mu wavelength range

We demonstrate a broadband digital Fourier Transform (dFT) spectrometer addressing wavelength monitoring applications in the 2.3-mu m wavelength range. The spectrometer is built in a silicon-on-insulator platform and the design allows its fabrication with CMOS-compatible tools. We report an operating bandwidth of 130 nm around 2.3 mu m wavelength using an efficient algorithm for sparse spectra to retrieve the wavelength with an accuracy of 100 pm. The spectrometer can also resolve two laser lines up for dFT spectrometers, which takes advantage of the sparse nature of the spectrum

Open data, Science and Society: launching Oasis, the flagship initiative of the Istituto Italiano di Antropologia

The Open Data philosophy has gained considerable momentum in recent years, both in society and the scientific community. The accessibility via web of open data from the public sector has remarkably increased in the last decade, although there are substantial differences among nations (http://datacatalogs.org/). The expectation of many citizens, organizations and pressure groups (the so called “open government” movement) is that the free release of data from public administrations may help increase government transparency and accountability

Efficient nanoscale photonic devices and monolithic electronic-photonic subsystems in sub-100 nm SOI CMOS

We demonstrate efficient photonic devices that rely on sub-100nm features in unmodified 45nm SOI CMOS, including photonic crystals, array-antenna grating couplers, and modulators. We then show monolithically integrated electronicphotonic systems comprising millions of transistors and thousands of photonic devices, including a complete chip-to-chip photonic link

Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: the challenge ahead.

Lifestyle factors are responsible for a considerable portion of cancer incidence worldwide, but credible estimates from the World Health Organization and the International Agency for Research on Cancer (IARC) suggest that the fraction of cancers attributable to toxic environmental exposures is between 7% and 19%. To explore the hypothesis that low-dose exposures to mixtures of chemicals in the environment may be combining to contribute to environmental carcinogenesis, we reviewed 11 hallmark phenotypes of cancer, multiple priority target sites for disruption in each area and prototypical chemical disruptors for all targets, this included dose-response characterizations, evidence of low-dose effects and cross-hallmark effects for all targets and chemicals. In total, 85 examples of chemicals were reviewed for actions on key pathways/mechanisms related to carcinogenesis. Only 15% (13/85) were found to have evidence of a dose-response threshold, whereas 59% (50/85) exerted low-dose effects. No dose-response information was found for the remaining 26% (22/85). Our analysis suggests that the cumulative effects of individual (non-carcinogenic) chemicals acting on different pathways, and a variety of related systems, organs, tissues and cells could plausibly conspire to produce carcinogenic synergies. Additional basic research on carcinogenesis and research focused on low-dose effects of chemical mixtures needs to be rigorously pursued before the merits of this hypothesis can be further advanced. However, the structure of the World Health Organization International Programme on Chemical Safety 'Mode of Action' framework should be revisited as it has inherent weaknesses that are not fully aligned with our current understanding of cancer biology