8 mm long channel waveguides were manufactured in polycrystalline diamond with inductively coupled plasma etching and characterized in terms of mode-profile and propagation loss in the 1.5 - 3.4 mu m spectral region. ...
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8 mm long channel waveguides were manufactured in polycrystalline diamond with inductively coupled plasma etching and characterized in terms of mode-profile and propagation loss in the 1.5 - 3.4 mu m spectral region. As proof of principle, the waveguides were evaluated in an evanescent field sensing setup targeting the CH absorption peak of isopropanol at similar to 3.4 mu m, showing good agreement with numerical finite element simulations. (C) 2016 Optical Society of America
We have studied the optical properties of channel waveguides written using a femtosecond laser in tellurite-zinc glasses doped with metallic silver (%TeO2%ZnO:Ag). Our findings showed that the tellurium dioxide glasse...
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We have studied the optical properties of channel waveguides written using a femtosecond laser in tellurite-zinc glasses doped with metallic silver (%TeO2%ZnO:Ag). Our findings showed that the tellurium dioxide glasses could be significantly affected by the silver presence, even with low silver concentration. By properly choosing the parameters and glassy matrix the written waveguides presented lower optical insertion losses and greater refractive index change.
We report waveguides in Ni-doped Li2O-Ga2O3-SiO2 (Ni:LGS) glass and glass-ceramic (GC) fabricated with a femtosecond (fs) laser with repetition rate of 1 kHz. When the glass is annealed to form a GC, the waveguides ar...
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We report waveguides in Ni-doped Li2O-Ga2O3-SiO2 (Ni:LGS) glass and glass-ceramic (GC) fabricated with a femtosecond (fs) laser with repetition rate of 1 kHz. When the glass is annealed to form a GC, the waveguides are erased. However, in the GC the waveguides are not erased by annealing. In Ni:LGS GC a 415 nm absorption band was created by fs laser waveguide writing due to the creation of Ni nanoparticles with an estimated diameter of a few nm. Raman and photoluminescence spectra of the bulk and waveguide structures were indistinguishable;however, fluorescence decay profiles indicated more long lifetime components in the waveguide compared to the bulk. (C) 2014 Elsevier B.V. All rights reserved.
In this letter, we illustrate how metafilms (the two-dimensional equivalents of metamaterials, also referred to as metasurfaces) can be used to design novel waveguiding structures. Metafilm waveguides can be flexible ...
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In this letter, we illustrate how metafilms (the two-dimensional equivalents of metamaterials, also referred to as metasurfaces) can be used to design novel waveguiding structures. Metafilm waveguides can be flexible with low material and radiation losses. They are attractive alternatives to traditional core-cladding types of surface waveguides and, as such, could have potential applications at terahertz frequencies. We show comparisons to full-wave numerical results in order to validate first the proposed waveguiding structure and, second, the technique used in the analysis of the waveguide.
Three-dimensional complete photonic-bandgap materials offer unique opportunities regarding the integration of optical waveguide architectures in three dimensions. However, corresponding experimental realizations are t...
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Three-dimensional complete photonic-bandgap materials offer unique opportunities regarding the integration of optical waveguide architectures in three dimensions. However, corresponding experimental realizations are truly sparse. Here, we fabricate such waveguides using direct laser writing and a silicon double-inversion procedure. The optical characterization is in good agreement with theoretical calculations, raising hopes that even more complex architectures may soon come into reach. (C) 2010 Optical Society of America
The paper is devoted to a model of a mesoscopic system consisting of a pair of parallel planar waveguides separated by an infinitely thin semitransparent boundary modeled by a transverse delta interaction. We develop ...
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The paper is devoted to a model of a mesoscopic system consisting of a pair of parallel planar waveguides separated by an infinitely thin semitransparent boundary modeled by a transverse delta interaction. We develop the Birman-Schwinger theory for the corresponding generalized Schrodinger operator. The spectral properties become nontrivial if the barrier coupling is not invariant with respect to longitudinal translations, in particular, there are bound states if the barrier is locally more transparent in the mean and the coupling parameter reaches the same asymptotic value in both directions along the guide axis. We derive the weak-coupling expansion of the ground-state eigenvalue for the cases when the perturbation is small in the supremum and the L-1-norms. The last named result applies to the situation when the support of the leaky part shrinks: the obtained asymptotics differs from that of a double guide divided by a pierced Dirichlet barrier. We also derive an upper bound on the number of bound states.
作者：
Freitas, P.Krejcirik, D.Univ Lisbon
Dept Math Fac Motricidade Humana TU Lisbon Complexo InterdisciplinarAv Prof Gama Pinto 2 P-1649003 Lisbon Portugal Univ Lisbon
Grp Math Phys P-1649003 Lisbon Portugal Acad Sci Czech Republ
Dept Theoret Phys Inst Nucl Phys Prague 25068 Czech Republic
We consider the Laplacian in a curved two-dimensional strip of constant width squeezed between two curves, subject to Dirichlet boundary conditions on one of the curves and variable Robin boundary conditions on the ot...
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We consider the Laplacian in a curved two-dimensional strip of constant width squeezed between two curves, subject to Dirichlet boundary conditions on one of the curves and variable Robin boundary conditions on the other. We prove that, for certain types of Robin boundary conditions, the spectral threshold of the Laplacian is estimated from below by the lowest eigenvalue of the Laplacian in a Dirichlet-Robin annulus determined by the geometry of the strip. Moreover, we show that an appropriate combination of the geometric setting and boundary conditions leads to a Hardy-type inequality in infinite strips. As an application, we derive certain stability of the spectrum for the Laplacian in Dirichlet-Neumann strips along a class of curves of sign-changing curvature, improving in this way an initial result of Dittrich and Kriz (J. Phys. A, 35: L269-275, 2002).
The aim of this paper is to study the collision between the long surface water waves. This is done by considering the coupled KdV equations with the relevant constrains on the variable coefficients. The extended ratio...
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The aim of this paper is to study the collision between the long surface water waves. This is done by considering the coupled KdV equations with the relevant constrains on the variable coefficients. The extended rational traveling wave solutions are obtained. Various solutions of solitary waves, via soliton, periodic, elliptic and two-soliton solutions has also found. The waveguide properties of the characterizing two-soliton are shown to be a graded-index with reflection component and transmission with periodic distributions in long-distance communication. Here the linear refractive index and transmission are been shown to evolute towards solitonic waves enable to confirm data transverse by restricting expansion in low-cost telecommunications systems.
Surface plasmon polaritons（SPPs） are evanescent waves propagating along metal-dielectric interfaces, which provide an effective way to realize optical wave guiding with subwavelength confinement. Metallic nanostruct...
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Surface plasmon polaritons（SPPs） are evanescent waves propagating along metal-dielectric interfaces, which provide an effective way to realize optical wave guiding with subwavelength confinement. Metallic nanostructures supporting SPPs,that is, plasmonic waveguides, are considered as required components to construct nanophotonic devices and circuits with a high degree of miniaturization and integration. In this paper, various types of plasmonic waveguides operating in the visible, infrared, and terahertz regions are reviewed, and the status of the research on their fundamentals, fabrications,and applications is provided as well. First, we discuss the mechanisms of SPPs beyond the diffraction limit, and their launching methods. Then, the characteristics of SPPs on various plasmonic waveguides are reviewed, including top-down and bottom-up fabricated types. Considering applications, certain prototypes of plasmonic devices and circuits constructed by plasmonic waveguides for bio/chemo sensing, router, and light modulation are demonstrated. Finally, a summary and future outlook of plasmonic waveguides are given.
A fourth-order operator marching method for the Helmholtz equation in a waveguide is developed in this paper. It is derived from a new fourth-order exponential integrator for linear evolution equations. The method imp...
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A fourth-order operator marching method for the Helmholtz equation in a waveguide is developed in this paper. It is derived from a new fourth-order exponential integrator for linear evolution equations. The method improves the second-order accuracy associated with the widely used step-wise coupled mode method where the waveguide is approximated by segments that are uniform in the propagation direction. The Helmholtz equation is solved using a one-way reformulation based on the Dirichlet-to-Neumann map. An alternative version closely related to the coupled mode method is also given. Numerical results clearly indicate that the method is more accurate than the coupled mode method while the required computing effort is nearly the same.
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