Electrical characterization of sputter-deposited ZnO coatings on optical fibers

Chat with Graph Search

Ask any question about EPFL courses, lectures, exercises, research, news, etc. or try the example questions below.

DISCLAIMER: The Graph Chatbot is not programmed to provide explicit or categorical answers to your questions. Rather, it transforms your questions into API requests that are distributed across the various IT services officially administered by EPFL. Its purpose is solely to collect and recommend relevant references to content that you can explore to help you answer your questions.

Models of amorphous (HfO2)x(SiO2)(1), for varying hafnium, content x are generated by ab initio molecular dynamics. The structural properties are analyzed in terms of pair distribution functions from which typical bond lengths and coordination numbers are extracted. Electronic band gaps are calculated with a hybrid density functional and are found to decrease in a nonlinear way with increasing x, in accord with experimental observations. Static dielectric constants are evaluated through the application of a

We discuss the structural, electronic and dielectric properties of a model structure of the Si(100)-SiO2 interface that accounts for the amorphous nature of the oxide. After showing that the structural properties of this model are consistent with a variety of experimental data, we consider the variation of the valence and conduction band edges across the interface. Our calculations indicate that the width of the electronic structure transition from the substrate to the oxide is 0.7-0.8 nm. We also address t

Force/torque sensors compatible with magnetic resonance imaging (MRI) are required to develop haptic interfaces for neuroscientific investigations and robotic tools for interventional MRI. In this paper, we analyze the mechanical structure of classical and MRI compatible sensors from literature and demonstrate the critical role of the mechanical design on the sensing performance. A simple and efficient torque sensor based on light intensity measurement over optical fibers is introduced, which allows to plac

This paper is related to the characteristics of a traveling wave ultrasonic linear motor. After a brief state of the art of this type of motor, the working principle is presented. Then, to describe analytically the phenomena existing, a theoretical model is built using wave theory and contact mechanism laws. Analytical modeling is then validated by FEM simulations. Transient and steady-state responses of the system are obtained. In function of the voltage applied to the piezoelectric ceramics, the deformati

In ferroelectric materials, domain wall displacement plays a key role in the dielectric properties measured with respect to the driving field amplitude and frequency. The low to medium field dielectric response in many ferroic systems can be often described by classical Rayleigh model, which is rate-independent i.e., it depends only on the strength of ac signal. However experiments show that the nonlinear parameters are frequency dependent. Thus a more general approach, which can describe both purely nonlin

We investigate the dielectric permittivity of SiO2 on Si(100) substrates using a first-principles approach. It is shown that both the static and high-frequency dielectric constants of the oxide overlayer increase when the oxide thickness is reduced. This behavior of the overlayer is found to be well reproduced by a classical two-layer model in which the pure oxide and the suboxide layer are treated as distinct dielectrics. Implications for interfaces between silicon and high-k gate oxides are discussed. (C)

We introduce a density-functional perturbational scheme based on ultrasoft pseudopotentials for calculating dielectric tensors of periodic systems. We obtain a variational functional for the second-order derivative of the energy with respect to an electric field. Our scheme makes use of the correspondence between all-electron and pseudo-wave-functions introduced in the projector augmented wave method. While we here specifically focus on ultrasoft pseudopotentials, our scheme also covers the case of norm-con

A review of the properties of ferroelectric materials that are relevant to microwave tunable devices is presented: we discuss the theory of dielectric response of tunable bulk materials and thin films; the experimental results from the literature and from own work are reviewed; the correspondence between the theoretical results and the measured properties of tunable materials is critically analyzed; nominally pure, real (defected), and composite bulk materials and thin films are addressed. In addition, tech

We report, to our knowledge, the first active channel waveguide in Ti:sapphire. We have created [similar to] 1.4-μm high ribs in a [similar to] 10-μm thick Ti:sapphire planar waveguide by reactive ion etching. Following excitation by an Ar-ion laser, the rib structure showed channel-waveguide fluorescence emission. The mode profiles and the beam-parameter values (M2) were measured. The coupling efficiency of fluorescence emission into a single-mode fiber was an order of magnitude higher than for fluorescenc

PbTiO3 thin films were prepared from alkoxide solution precursors and crystallized onto Pt/TiO2/SiO2/Si substrates. Microscopy observations revealed that the complexity of the domain walls structure decreased with the grain size. Dielectric, electrostrictive, and piezoelectric properties of the films were characterized in details. A shift of the temperature of the dielectric permittivity maximum due to stresses in the plane of films has been observed. Electrostrictive M and Q coefficients were estimated by

We investigate numerically the spectrum of plasmon resonances for metallic nanowires with a nonregular cross section, in the 20-50 nm range. We first consider the resonance spectra corresponding to nanowires whose cross sections form different simplexes. The number of resonances strongly increases when the section symmetry decreases: A cylindrical wire exhibits one resonance, whereas we observe more than five distinct resonances for a triangular particle. The spectral range covered by these different resona

Two Mach-Zehnder interferometers (MZI), one with Y-junction-couplers and the other with multimode interference (MMI), were presented. Both MZI were developed in silicon-on-insulator (SOI) technology and used plasma dispersion effect for light phase modulation. Fiber-to-fiber insertion losses, absorption coefficients, optical coefficients modulated intensities as function of time and modulation extinction ratios versus signal frequencies were measured for these devices at various wavelengths. Both devices we

Electrical characterization of sputter-deposited ZnO coatings on optical fibers

Chat with Graph Search

Amorphous hafnium silicates: structural, electronic and dielectric properties

Atomic-scale modelling of the Si(100)-SiO2 interface

Design of a simple MRI/fMRI compatible force/torque sensor

Characteristics, modeling and simulation of a traveling wave ultrasonic linear motor

Analysis of the non linear domain wall response in ferroelectric thin films

Dielectric effect of a thin SiO2 interlayer at the interface between silicon and high-k oxides

Density-functional perturbational theory for dielectric tensors in the ultrasoft pseudopotential scheme

Ferroelectric materials for microwave tunable applications

Ti:sapphire rib channel waveguide fabricated by reactive ion etching of a planar waveguide

Properties of ferroelectric PbTiO3 thin films

Plasmon resonances of silver nanowires with a nonregular cross section

Intensity modulation in two Mach-Zehnder interferometers using plasma dispersion in silicon-on-insulator