Near-field distribution and propagation of scattering resonances in Vogel spiral arrays of dielectric nanopillars

In this work, we employ scanning near-field optical microscopy, full-vector finite difference time domain numerical simulations and fractional Fourier transformation to investigate the near-field and propagation behavior of the electromagnetic energy scattered at 1.56µm by dielectric arrays of silicon nitride nanopillars with chiral 1-Vogel spiral geometry. In particular, we experimentally study the spatial evolution of scattered radiation and demonstrate near-field coupling between adjacent nanopillars along the parastichies arms. Moreover, by measuring the spatial distribution of the scattered radiation at different heights from the array plane, we demonstrate a characteristic rotation of the scattered field pattern consistent with net transfer of orbital angular momentum in the Fresnel zone, within a few micrometers from the plane of the array. Our experimental results agree with the simulations we performed and may be of interest to nanophotonics applications

Gratings with an aperiodic basis: single-mode emission in multi-wavelength lasers

We propose a new class of gratings having multiple spatial frequencies. Their design relies on the use of small aperiodic grating sequences as unit cells whose repetition forms a superlattice. The superlattice provides well-defined Fourier components, while the choice of the unit cell structure enables the selection, modulation or suppression of certain Fourier components. Using these gratings to provide distributed feedback in mid-infrared quantum cascade lasers, we demonstrate simultaneous lasing on multiple well-defined and isolated longitudinal modes, each one having a sidemode suppression ratio of about 20 dB.United States. Air Force Office of Scientific Research (MURI 67N-1069926)Harvard University (Nanoscale Systems and Engineering Center)United States. Air Force (‘Deterministic Aperiodic Structures for Onchip Nanophotonic and Nanoplasmonic Device Applications’ under award no. FA9550-10-1- 0019)National Science Foundation (U.S.) (NSF CAREER Award ECCS-0846651)Georgia Institute of Technology (Steve W. Chaddick Endowed Chair of OptoElectronics

Raman Amplifier Based on Amorphous Silicon Nanoparticles

The observation of stimulated Raman scattering in amorphous silicon nanoparticles embedded in Si-rich nitride/silicon superlattice structures (SRN/Si-SLs) is reported. Using a 1427 nm continuous-wavelength pump laser, an amplification of Stokes signal up to 0.9 dB/cm at 1540.6 nm and a significant reduction in threshold power of about 40% with respect to silicon are experimentally demonstrated. Our results indicate that amorphous silicon nanoparticles are a great promise for Si-based Raman lasers

Luminescence Properties of a Fibonacci Photonic Quasicrystal

We report the realization of an active one-dimensional Fibonacci photonic quasi-crystal via spin coating. Manipulation of the luminescence properties of an organic dye embedded in the quasi-crystal is presented and compared to theoretical simulations. The luminescence occurs via the pseudo-bandedge mode and follows the dispersion properties of the Fibonacci crystal. Time resolved luminescence measurement of the active structure shows faster spontaneous emission rate, indicating the effect of the large photon densities available at the bandedge due to the presence of critically localized states. The experimental results are in excellent agreement with the theoretical calculations.Comment: PDF file, 14 pages 4 figure

Cost analysis of GER-induced asthma: a controlled study vs. atopic asthma of comparable severity.

Abstract Bronchial asthma is a costly disease: while the role of pharmaceutical strategies was greatly emphasised in order to alleviate its economic burden,the aetiological approach to asthma has received much less attention from this point of view. The impact of gastro-oesophageal reflux (GER)-related asthma was assessed in comparison to atopic asthma in 262 matched patients,and the corresponding direct and indirect annual costs calculated. All subjects were screened by means of a 95-item self-questionnaire. The overall resource utilisation was calculated for the last 12 months. Drug-induced annual costs were euro 290.4 (interquartile range-iqr 32.8) in atopic and euro 438.4 (iqr 27.8) in GER-related asthma (p<0.001); expenditure for medical consultations and diagnostics were euro 166.1 (iqr 14.8) vs. euro 71.6 (iqr 11.0) (p<0.001),and euro 338.4 (20.0) vs. 186.9 (iqr 26.5) (p<0.001),respectively. Direct costs due to hospital admissions and indirect costs due to absenteeism were also higher in GER-related asthmatics: 2.201.7+/-90.0 vs. euro 567.1+/-11.0 (p<0.001),and euro 748.7+/-94.7 vs. euro 103.6+/-33.9 (p<0.001),respectively. The total annual cost per patient was euro 1246.7 (iqr 1979.6) in atopic and euro 3967.1 (iqr 3751.5) in GER-related asthma,p<0.001. In conclusion,GER-induced asthma has a more relevant economic impact on healthcare resources than atopic asthma. Although further studies are needed,present data tend to demonstrate that when facing difficult asthma (GER-related asthma in this case),the aetiological assessment of the disease plays a critical role in optimising the approach to patients' needs

Organ-on-a-chip: current gaps and future directions.

As an emerging hot topic of the last decade, Organ on Chip (OoC) is a new technology that is attracting interest from both basic and translational scientists. The Biochemical Society, with its mission of supporting the advancement of science, with addressing grand challenges that have societal impact, has included OoC into their agenda to review the current state of the art, bottlenecks and future directions. This conference brought together representatives of the main stakeholders in the OoC field including academics, end-users, regulators and technology developers to discuss and identify requirements for this new technology to deliver on par with the expectations and the key challenges and gaps that still need to be addressed to achieve robust human-relevant tools, able to positively impact decision making in the pharmaceutical industry and reduce overreliance on poorly predictive animal models