Guided-wave approaches to spectrally selective energy absorption

Results of experiments designed to demonstrate spectrally selective absorption in dielectric waveguides on semiconductor substrates are reported. These experiments were conducted with three waveguides formed by sputtering films of PSK2 glass onto silicon-oxide layers grown on silicon substrates. The three waveguide samples were studied at 633 and 532 nm. The samples differed only in the thickness of the silicon-oxide layer, specifically 256 nm, 506 nm, and 740 nm. Agreement between theoretical predictions and measurements of propagation constants (mode angles) of the six or seven modes supported by these samples was excellent. However, the loss measurements were inconclusive because of high scattering losses in the structures fabricated (in excess of 10 dB/cm). Theoretical calculations indicated that the power distribution among all the modes supported by these structures will reach its steady state value after a propagation length of only 1 mm. Accordingly, the measured loss rates were found to be almost independent of which mode was initially excited. The excellent agreement between theory and experiment leads to the conclusion that low loss waveguides confirm the predicted loss rates

Trapping of light beams and formation of spatial solitary waves in quadratic nonlinear media

Summary form only given. In this paper we report the outcome of our comprehensive investigations to study the dynamics of the beam trapping in both bulk crystals and optical planar waveguides made of quadratic nonlinear media in second-harmonic generation configurations. We address and discuss the suitable experimental conditions required to form spatial solitary waves in critical phase-matching and quasi-phase-matching settings.Peer ReviewedPostprint (published version

Intra- and interspecies transmission of H7N7 highly pathogenic avian influenza virus during the avian influenza epidemic in the Netherlands in 2003

The poultry epidemic of H7N7 highly pathogenic avian influenza (HPAI) virus in the Netherlands in 2003 was probably the result of the introduction of an H7N7 low pathogenic avian influenza (LPAI) virus (by interspecies transmission from wild birds) and the subsequent intraspecies transmission of this virus in poultry. The intraspecies transmission of the ensuing H7N7 HPAI virus was very successful both within and between flocks. Consequently, in the two poultry-dense areas that were affected, the epidemic could only be stopped by eliminating all poultry in the region. According to the spatial models these are the only areas where this was the case in the Netherlands. There was also interspecies transmission to mammals, i.e. to pigs and to humans. For pigs it was shown that possible subsequent intraspecies transmission was negligible (R0 <1). With hindsight the same was probably also true for human

Spatially incoherent modulational instability in a non local medium

We investigate one-dimensional transverse modulational instability in a non local medium excited with a spatially incoherent source. Employing undoped nematic liquid crystals in a planar pre-tilted configuration, we investigate the role of the spectral broadening induced by incoherence in conjunction with the spatially non local molecular reorientation. The phenomenon is modeled using the Wigner transform.Comment: 13 pages with 4 figures included. To be published in Laser Physics Letter

Phase Controlled All-Optical Switching In Rocking Filter Fibers

We demonstrate experimentally that all-optical switching of a strong beam can be controlled by the phase of a weak beam in a rocking rotator fiber

New nonlinear dielectric materials: Linear electrorheological fluids under the influence of electrostriction

The usual approach to the development of new nonlinear dielectric materials focuses on the search for materials in which the components possess an inherently large nonlinear dielectric response. In contrast, based on thermodynamics, we have presented a first-principles approach to obtain the electrostriction-induced effective third-order nonlinear susceptibility for the electrorheological (ER) fluids in which the components have inherent linear, rather than nonlinear, responses. In detail, this kind of nonlinear susceptibility is in general of about the same order of magnitude as the compressibility of the linear ER fluid at constant pressure. Moreover, our approach has been demonstrated in excellent agreement with a different statistical method. Thus, such linear ER fluids can serve as a new nonlinear dielectric material.Comment: 11 page

All-Optical Integrated Mach-Zehnder Switching Due To Cascaded Nonlinearities

We demonstrate all-optical switching using the cascaded second order nonlinearity in a fully integrated, asymmetric Mach Zehnder interferometer implemented in lithium niobate channel waveguides. We obtained an 8:1 switching ratio

Quasi-Phase Matched Surface Emitting Second Harmonic Generation In Poled Polymer Waveguides

Quasi-phase matched (QPM) surface emitting second harmonic generation was demonstrated with nonlinear/linear multilayer waveguides in poled polymer based devices. The nonlinear/linear multilayer film was fabricated with a 4-dimethylamino-4\u27-nitrostilbene (DANS) side chain polymer and a cross-linkable clear polymer. Large efficiency improvement was observed with a combination of QPM and strong field parallel poling

The Growing Family Of Spatial Solitons

The recent proliferation of spatial solitons which have been observed experimentally is discussed

Field trial for assessment of avian influenza vaccination effectiveness in Indonesia

The aim of this field study was to determine the efficacy of vaccination against highly pathogenic avian influenza (HPAI) virus strain H5N1 in Indonesia. A limited, prototype clinical trial was performed using a standardised treatment group, in which poultry flocks were vaccinated at least twice with a selected H5N1 vaccine, and a control group comprising flocks treated with nonstandardised procedures chosen by the farmer. Each group consisted of six flocks comprising either layers or native chickens. Haemagglutination inhibition (HI) antibody levels were determined by regular serum sampling, and outbreak surveillance relied on non-Al-vaccinated sentinel birds. After three vaccinations high antibody titres were produced in the treatment group, and the percentage of layers with an HI titre > 40 was approximately 90%. Although no conclusions can be drawn regarding reduction of virus transmission, this study demonstrated that 11 farms remained free from Al during the observation period, and that a surveillance programme based on differentiating infected from vaccinated animals (DIVA) can be implemented