Search results for "guides"

Photo-thermal control of surface plasmon mode propagation at telecom wavelengths

2016

Surface plasmon polaritons (SPPs) is the promising versatile platform proposed for guiding electromagnetic waves at nanoscale dimensions. In this context dynamic control of SPPs prop- agation is of paramount importance. Thermo-optical (TO) effect is considered as an efficient technique for performing active control of plasmonic devices. Among the thermo-optical based plasmonic devices demonstrated so far TO coefficient is dominantly provided by a dielectric material on top of the metal sustaining the SPP mode, however, the role of TO properties of the metal has been rarely investigated for plasmonic applications especially at the telecom frequency ranges. Therefore, the aim of this thesis i…

A RADIATION CONDITION FOR UNIQUENESS IN A WAVE PROPAGATION PROBLEM FOR 2-D OPEN WAVEGUIDES

2009

We study the uniqueness of solutions of Helmholtz equation for a problem that concerns wave propagation in waveguides. The classical radiation condition does not apply to our problem because the inhomogeneity of the index of refraction extends to infinity in one direction. Also, because of the presence of a waveguide, some waves propagate in one direction with different propagation constants and without decaying in amplitude. Our main result provides an explicit condition for uniqueness which takes into account the physically significant components, corresponding to guided and non-guided waves; this condition reduces to the classical Sommerfeld-Rellich condition in the relevant cases. Final…

A method of variation of boundaries for waveguide grating couplers

2008

We describe a method for calculating the solution of the electromagnetic field in a non-rectilinear open waveguide by using a series expansion, starting from the field of a rectilinear waveguide. Our approach is based on a method of variation of boundaries. We prove that the obtained series expansion converges and we provide a radiation condition at infinity in such a way that the problem has a unique solution. Our approach can model several kinds of optical devices which are used in optical integrated circuits. Numerical examples will be shown for the case of finite aperiodic waveguide grating couplers.

Corrections to “Multipactor Susceptibility Charts for Ridge and Multi-Ridge Waveguides” [Dec 12 3601-3607]

2014

The authors have detected an error in Section IV-A in the above paper (ibid., vol. 59, no. 12, pp. 3601-3607, Dec. 2012). The analyzed rectangular waveguide in the actual version of the article is the WR137, instead of the WR90. As a consequence, the corrections presented here have to be implemented.

Wideband modeling of cascaded H-plane waveguide junctions using the generalised impedance matrix representation

2009

A strong interest in H-plane waveguide components composed of a large number of cascaded planar junctions is recently renewed. Therefore, the more efficient development of full-wave analysis tools of such devices is again receiving consideration, specially for its potential use within modern design tools. A novel technique for providing the wideband generalised impedance matrix representation of the inductive devices in the form of pole expansions, thus extracting the most expensive computations from the frequency loop is proposed. For such purpose, the whole device is first decomposed into simpler building blocks, i.e. planar junctions and uniform waveguides, which are modelled in terms of…

Efficient Analysis and Design Strategies for Evanescent Mode Ridge Waveguide Filters

2006

In this paper, a research on the compromises arisen in the design of traditional evanescent mode waveguide filters is carried out. As a result, clear design methodologies for optimizing length, losses, power handling and spurious-free out-of-band response are developed. In addition, an efficient and very accurate modal analysis tool for this kind of structures is presented. Several filters have been designed according to the different strategies proposed, and a prototype has been finally manufactured. Measurements and filter dimensions validate the proposed design procedures.

Efficient FDTD analysis of discontinuities in a square coaxial waveguide

1996

Study of new tellurite glasses in the TeO2-ZnO-La2O3 (TZL) system for the manufacturing of mid-infrared multimaterial optical fibers and specialty op…

2023

This thesis work was carried out using tellurite glasses from the TeO2-ZnO-La2O3 (TZL) ternary diagram for optical fibers manufacturing. The choice to use this system is motivated by the ambition to improve the transmission of optical signals within oxide glasses for which absorption bands related to OH groups are present in the transparency window. A structural study is first carried out on these glasses by Raman spectroscopy in order to understand the influence of the composition on physicochemical properties (especially on optical and thermal properties) but also to estimate the ability of a vitreous matrix to reorganize when subjected to a thermal solicitation such as the preform-to-fib…

Tourisme Sportif et Identités : Les pratiquants de canoë en Zambie

2013

Cet article repose sur une enquête sur les usages sociaux du canoë en Zambie. Il a pour objectif de décrire les caractéristiques des relations sociales qui se nouent entre étrangers et « populations locales ». Si l’organisation de l’activité recouvre une visée touristique pour nombre de pays africains, touristes et habitants entrent peu en interaction en dehors de la pratique des loisirs. Pour étudier l’identité, il s’agit de caractériser la genèse du tour en canoë afin de saisir l’émergence de modes d’appréhension de l’Autre dans le cadre du loisir en Zambie. La singularité des relations sociales entre populations occidentales et africaines pose la question de la différence culturelle, au …

Las publicaciones divulgativas como vehículo de difusión del patrimonio arqueológico: bibliografía de guías arqueológicas en España 1975-2005

2008

Se realiza una aproximación a las publicaciones de carácter divulgativo como medio para difundir y dar a conocer el patrimonio arqueológico. Para ello, se identifica y caracteriza un determinado género de publicaciones divulgativas: las guías arqueológicas. Se presenta una bibliografía de la literatura de este género publicada a lo largo de las tres últimas décadas en España, analizando la evolución diacrónica del número de publicaciones, la cobertura geográfica, las entidades editoras, la estructura y los contenidos recogidos en este tipo de obras. We analyse Popular Science Archaeological Books as a way of spreading the popularization of archaeological heritage. In that sense, we identifi…