Observation of Enhanced Beaming from Photonic Crystal Waveguides

We report on the experimental observation of the beaming effect in photonic crystals enhanced via surface modes. We experimentally map the spatial field distribution of energy emitted from a subwavelength photonic crystal waveguide into free-space, rendering with crisp clarity the diffractionless beaming of energy. Our experimental data agree well with our numerical studies of the beaming enhancement in photonic crystals with modulated surfaces. Without loss of generality, we study the beaming effect in a photonic crystal scaled to microwave frequencies and demonstrate the technological capacity to deliver long-range, wavelength-scaled beaming of energy.Comment: 4 pages, 6 figure

Clinician adherence to a standardized assessment battery across settings and disciplines in a poststroke rehabilitation population

none12siObjectives: (1) To examine clinician adherence to a standardized assessment battery across settings (acute hospital, inpatient rehabilitation facilities [IRFs], outpatient facility), professional disciplines (physical therapy [PT], occupational therapy, speech-language pathology), and time of assessment (admission, discharge/monthly), and (2) to evaluate how specific implementation events affected adherence. Design: Retrospective cohort study. Setting: Acute hospital, IRF, and outpatient facility with approximately 118 clinicians (physical therapists, occupational therapists, speech-language pathologists). Participants: Participants (N=2194) with stroke who were admitted to at least 1 of the above settings. All persons with stroke underwent standardized clinical assessments. Interventions: Not applicable. Main Outcome Measures: Adherence to Brain Recovery Core assessment battery across settings, professional disciplines, and time. Visual inspections of 17 months of time-series data were conducted to see if the events (eg, staff meetings) increased adherence >= 5% and if so, how long the increase lasted. Results: Median adherence ranged from .52 to .88 across all settings and professional disciplines. Both the acute hospital and the IRF had higher adherence than the outpatient setting (P = 5% increase in adherence the following month, with 6 services (60%) maintaining their increased level of adherence for at least 1 additional month. Conclusions: Actual adherence to a standardized assessment battery in clinical practice varied across settings, disciplines, and time. Specific events increased adherence 40% of the time with those gains maintained for >1 month 60% of the time. (C) 2013 by the American Congress of Rehabilitation MedicinemixedBland, Marghuretta D.; Sturmoski, Audra; Whitson, Michelle; Harris, Hilary; Connor, Lisa Tabor; Fucetola, Robert; Edmiaston, Jeff; Huskey, Thy; Carter, Alexandre; Kramper, Marian; Corbetta, Maurizio; Lang, Catherine E.Bland, Marghuretta D.; Sturmoski, Audra; Whitson, Michelle; Harris, Hilary; Connor, Lisa Tabor; Fucetola, Robert; Edmiaston, Jeff; Huskey, Thy; Carter, Alexandre; Kramper, Marian; Corbetta, Maurizio; Lang, Catherine E

Near-field optical investigations of photonic crystal microresonators

We present an overview of our work on the application of scanning near-field optical microscopy (SNOM) to photonic crystal structures. Our results show that SNOM can be used to map the subwavelength confinement of light to a point-defect in a 2D photonic crystal microresonator. Comparison with numerical modelling shows that SNOM is able to resolve patterns in the intensity distribution that are due to the slight non-uniformity in the crystal structure. We also discuss the future possibilities for applications of different modes of SNOM to photonic crystal devices

A novel fabrication method for fluorescence-based apertureless scanning near-field optical microscope probes

We report a novel method for the fabrication of probes with localized sub-wavelength fluorescing media at their extremities. We present our first results and discuss future plans to extend this technique to the systematic fabrication of fluorescent probes for apertureless scanning near-field optical microscopy

Direct spectroscopy of a deep two-dimensional photonic crystal microresonator

Photonic crystals based on macroporous silicon with fundamental band gaps in the middle infrared region 3.4-5.8 mum were fabricated. Scanning probe optical microscopy and laser spectroscopy were combined to examine a deep two-dimensional photonic crystal microresonator based on a single point defect. Two sharp resonances were recorded in the band gap, in excellent agreement with the results of numerical simulations. Such a microresonator with high-quality factors and a subwavelength mode extension could be used for a range of applications including integrated optical gas sensors

Highly directional emission from photonic crystal waveguides of subwavelength width

Recently it has been shown that it is possible to achieve directional emission out of a subwavelength aperture in a periodically corrugated metallic thin film. We report on theoretical and experimental studies of a related phenomenon concerning light emitted from photonic crystal waveguides that are less than a wavelength wide. We find that the termination of the photonic crystal end facets and an appropriate choice of the wavelength are instrumental in achieving very low numerical apertures. Our results hold promise for the combination of photonic crystal waveguides with conventional optical systems such as fibers, waveguides, and freely propagating light beams

Transmission of a Microcavity Structure in a Two-Dimensional Photonic Crystal Based on Macroporous Silicon

Photonic crystals consist of regularly arranged dielectric scatterers of dimensions on a wavelength scale, exhibiting band gaps for photons, analogous to the case of electrons in semiconductors. Using electrochemical pore formation in n-type silicon, we fabricated photonic crystals consisting of air cylinders in silicon. The starting positions of the pores were photolithographically pre-defined to form a hexagonal lattice of a=1.58 mm. The photonic crystal was microstructured to make the photonic lattice accessible for optical characterization. Samples with di#erent filling factors were fabricated to verify the gap map of electric and magnetic modes using Fourier-transform infrared (IR) spectroscopy. The complete band gap could be tuned from 3.3 to 4.3 mm wavelength. We were able to embed defects such as waveguide structures or microcavities by omitting certain pores. We carried out transmission measurements using a tunable mid-IR optical parametric oscillator. The resonance is compare..

Intérêt thérapeutique des isoflavones de soja

Si le soja est une plante connue depuis des millénaires comme aliment très riche en protéines et en lipides, ce n'est que depuis une vingtaine d'années que les isoflavones qu'elle contient suscitent un intérêt considérable surtout, actuellement, leurs formes aglycones. Ces dernières, daidzéine, glycitéine et génistéine sont des substances naturelles à activité hormonale. On leur prête de nombreux effets cliniques en gynécologie, cardiologie et cancérologie. Cependant, bien que plusieurs essais cliniques concluent positivement sur leur intérêt, la faiblesse des cohortes étudiées laisse encore planer un doute scientifique, ce qu'a souligné l'AFSSAPS lors de son récent rapport. Il est urgent que des essais cliniques portant sur un grand nombre de patients soient publiés pour confirmer tout l'intérêt de ces phytoestrogènes.TOULOUSE3-BU Santé-Centrale (315552105) / SudocSudocFranceF

A model system for two-dimensional and three-dimensional photonic crystals: macroporous silicon

A review of the optical properties of two-dimensional and three-dimensional photonic crystals based on macroporous silicon is given. As macroporous silicon provides structures with aspect ratios exceeding 100, it can be considered to be an ideal two-dimensional photonic crystal. Most of the features of the photonic dispersion relation have been experimentally determined and were compared to theoretical calculations. This includes transmission and reflection of finite and bulk photonic crystals and their variation with the pore radius to determine the gap map. All measurements have been carried out for both polarizations separately since they decouple in two-dimensional photonic crystals. Moreover, by inhibiting the growth of selected pores, point and line defects were realized and the corresponding high-Q microcavity resonances as well as waveguiding properties were studied via transmission. The tunability of the bandgap was demonstrated by changing the refractive index inside the pores caused by an infiltrated liquid crystal undergoing a temperature-induced phase transition. Finally different realizations of three-dimensional photonic crystals using macroporous silicon are discussed. In all cases an excellent agreement between experimental results and theory is observed