Tailoring the spectral response of add/drop single and multiple resonators in silicon-on-insulator

Channel dropping waveguide filters based on single and technology are of great interest due to their compactness multiple resonators in silicon-on-insulator （SOI） and high wavelength selectivity, which is a desirable feature for photonic modulators, detectors, and other optically integrated components in telecommu- nication systems, in particular for wavelength division multiplexing （WDM） systems. Particular advantage of these filters is that they are capable of producing relatively large free spectral range （FSR） as well as narrow 3-dB bandwidth of the filter resonances. Herein we sibility of designing mono-mode and （nearly） polarization with the FSR in excess of 30 nm. report experimental results and discuss the posindependent SOI ring and racetrack resonators     

Tailoring the spectral response of add/drop single and multiple resonators in silicon-on-insulator Invited Paper

Channel dropping waveguide filters based on single and multiple resonators in silicon-on-insulator (SOI) technology are of great interest due to their compactness and high wavelength selectivity, which is a desir- able feature for photonic modulators, detectors, and other optically integrated components in telecommu- nication systems, in particular for wavelength division multiplexing (WDM) systems. Particular advantage of these filters is that they are capable of producing relatively large free spectral range (FSR) as well as narrow 3-dB bandwidth of the filter resonances. Herein we report experimental results and discuss the pos- sibility of designing mono-mode and (nearly) polarization independent SOI ring and racetrack resonators with the FSR in excess of 30 nm.     

Die degradative Extrusion — Stand und Aussichten

Zusammenfassung Das chemisch-stoffliche Recycling von thermoplastischen Kunststoffen mit Einsatz in der Petrochemie, in der Metallurgie u.a. verlangt eine sorgfältige Aufbereitung in ein den Spezifikationen der Großanlagen angepaßtes homogenes, pump- oder pneumatisch-förderbares Gut. Eine bisher großtechnisch noch nicht benutzte Methode ist diedegradative Extrusion. Sie wurde jedoch von verschiedenen Laboratorien intensiv auf ihre Anwendungsbreite und die erforderliche Ausrüstung in einem solchen Maße erforscht, daß Großanlagen sofort eingerichtet werden könnten. Hieraus lassen sich auch die zu erwartenden Kosten von Anlagen und Betrieb beliebig großer Anlagen abschätzen. Die möglichen Anwendungen umfassen alle Thermoplaste und erlauben auch die Aufarbeitung von 100% PVC. Hierüber wird zusammenfassend berichtet.

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Degradative extrusion — State and prospects

Summary The chemical recycling of thermoplastics from post consumer waste needs a preparation in a special process. The waste has to be homogenized to fullfil the specification of the downstreams following petrochemical or metallurgical processes and to be transferred in a state that allows to transport this product either as a liquid or as granules pneumatically. There are some different possible processes; the youngest of them is thedegradative extrusion. Although it has been carefully tested and seems to be cheaper than the others, it is not yet used in industrial practice. The tests have been made on machines of different size and throughputs and with different materials and mixtures of thermoplastics. By this reason, a broad knowledge exists how to design such a plant of any size and kind of material and what are the necessary investment and production costs. In contrary to all other processes, it is possible to degrade 100% of PVC as well.

Part of the symposium held in Vienna in honour of Prof.Mark's 100^th birthday; for contributions, see journal of Macromolecular Science, Pure and Applied ChemistryA33 (6), 1996.     

Equivalent currents for second-order diffraction by the edges of perfectly conducting polygonal surfaces

Equivalent, electric and magnetic, edge currents for arbitrary aspects of observation are derived for second-order diffraction by the edges of perfectly conducting, flat, polygonal surfaces. The physical model underlying the derivation is that each illuminated rectilinear edge segment excites a fringe current on the surface, acting as if it were part of an infinite straight edge. The surface wave associated with this fringe current traverses the surface along the grazing diffracted rays until it strikes an opposite edge segment, and its illumination area on the surface is delimited according to the finite length of the initiating edge segment. The "ray coordinate" measured along a grazing diffracted ray is chosen as the integration variable complementary to the edge coordinate in the fringe current radiation integral. The one-dimensional "radiation" integral over this coordinate is evaluated asymptotically in the high-frequency limit and reduced to the sum of two endpoint contributions. The upper integration limit contribution is east in the form of equivalent edge currents pertaining to the termination point of the grazing diffracted ray. These currents are responsible for the dominant part of the second-order edge diffraction. Their expressions incorporate the well-known Fresnel function (which in many eases may be replaced by its asymptotic approximation) and are finite for any combination of incidence and scattering directions, except when both of them coalesce with the grazing diffracted ray. The developed method applies both to flat plates and to plane faces of thick bodies. Examples of backscatter calculations for flat plates are given which exhibit certain improvements over previous calculations by Sikta, as compared with measured data.     

Transition functions for high-frequency diffraction by a curvedperfectly conducting wedge. III. Extension to overlapping transitionregions

For pt.II see ibid., vol.37, no.9, p.1080-5(1989). The asymptotic theory of pt.II is extended to the case where the transition region of edge diffraction overlaps the region of surface diffraction. The extension is performed by incorporating Ufimtsev's theory in the spectral domain approach. The dominant part of the scattered field is obtained by asymptotic evaluation of the radiation integral for the Fock current unperturbed by the edge, wherein the surface curvature and the finite distance to the field point are explicitly taken into account. The correction part, due to the fringed currents excited by the edge, is evaluated by the simpler procedure of pt.II. The dominant part involves a pair of new universal functions independent of the wedge angle. The coincide with those deduced in Pt.I from the rigorous canonical solution for a perfectly conducting cylindrically curved sheet. At very high frequencies, the present solution merges smoothly with the partially uniform solution of pt.II and with Keller's solution in the appropriate angular domains of incidence and scattering