Search results for "Poling"

Inspirations for EO polymer design gained from modeling of chromophore poling by Langevin dynamics

2013

One of the possibilities to create organic molecular material for NLO applications are polymers with dispersed NLO active chromophores. These molecules must be acentrically ordered by applying an external electric poling field. The NLO efficiency depends on dipole moment, molecular hyperpolarizabilities, concentration of the chromophores and external poling field strength. Calculating, from first principles, the extent of the alignment and via this NLO efficiency has proven to be challenging. One approach to solve this problem is pure analytic statistical mechanics treatment, what could be enhanced by Monte Carlo ( MC ) statistical mechanical modelling. The chromophore molecules usually hav…

Nonstoichiometric silica mask to fabricate reverse proton-exchange waveguides in lithium niobate crystals

2004

Producing channel waveguides requires a photolithographic mask, but the standard technique of using thermally evaporated metal films for proton exchange has proved to be unsuitable for withstanding the rather aggressive process of reverse proton exchange. We report the fabrication of a nonstoichiometric silica mask by ion-plating plasma-assisted deposition. This mask is strong enough to resist both direct and reverse proton exchange and is also compatible with anisotropic dry etching for patterning the mask and with electric field poling. Our technique is a practical alternative to the use of SiO2 sputtered masks.

Studies of host-guest thin films of corona-poled betaine-type polar molecules by kelvin probe technique and atomic force microscopy

2004

In this work betaine-type molecules were investigated. As a result of the asymmetry of charge distribution, molecules possess in the ground state a considerable permanent dipole moment. The decay of surface potential of poled polymer films is dependent at least on two relaxation processes. The influence of glass transition of PMMA on thermal dependence of the surface potential is shown. The transition temperature, where no changes of the surface potential appeared, is related to glass transition temperature of the host-guest system. The topography of the film surface was obtained by AFM.

Photoelectropoling of azobenzene chromophores in molecular films

1994

The photoinduced reorientation and photoelectropoling processes were investigated in molecular films of aliphatically substituted azobenzenes. While polarized illumination leads to a conversion of isotropic samples into anisotropic ones, upon application of external electric fields even macroscopically polar materials are created. The macroscopic polarity can be reversed under suitable experimental conditions. Order parameters as a function of the poling field were determined by Stark spectroscopy. Using atomic force microscopy it is shown that the structure of the sample is well defined on a microscopic length scale, whereas on a macroscopic length scale it is not.

Characterization of PP-cLT Waveguides for phase conjugation in the C + L band of Optical Communications

2010

Electric field modification of magnetotransport in Ni thin films on (011) PMN-PT piezosubstrates

2015

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Appl. Phys. Lett. 106, 062404 (2015) and may be found at https://doi.org/10.1063/1.4907775 This study reports the magnetotransport and magnetic properties of 20 nm-thick polycrystalline Ni films deposited by magnetron sputtering on unpoled piezoelectric (011) [PbMg1/3Nb2/3O3]0.68-[PbTiO3]0.32 (PMN-PT) substrates. The longitudinal magnetoresistance (MR) of the Ni films on (011) PMN-PT, measured at room temperature in the magnetic field range of −0.3 T < μ0H < 0.3 T, is found to depend on the crystallographic direction and polarization state …

Comparison of Exclusive Double Poling to Classic Techniques of Cross-country Skiing

2018

Introduction: This study aimed to 1) determine basic physiological demands during a simulated on-snow cross-country skiing (XCS) race when using grip-waxed skis (all classic XCS techniques [CLASSIC]), versus glide-waxed skis for exclusive double poling (DP) and 2) analyze in which track sections DP is different from CLASSIC under controlled gliding conditions in elite junior and senior skiers. Methods: Nineteen male and female elite XC skiers performed 1) two randomized simulated XCS races over 5.3 km using DP or CLASSIC measuring section times, V˙ O2, HR, blood lactate, and RPE; and 2) V˙ O2peak tests using diagonal stride and DP on treadmill. Results: The total group showed no differences…

Changes in performance and poling kinetics during cross-country sprint skiing competition using the double-poling technique

2013

In this study, changes in skiing performance and poling kinetics during a simulated cross-country sprint skiing competition were investigated. Twelve elite male cross-country skiers performed simulated sprint competition (4 x 1,150 m heat with 20 min recovery between the heats) using the double-poling technique. Vertical and horizontal pole forces and cycle characteristics were measured using a force plate system (20-m long) during the starting spurt, racing speed, and finishing spurt of each heat. Moreover, heat and 20-m phase velocities were determined. Vertical and horizontal pole impulses as well as mean cycle length were calculated. The velocities of heats decreased by 2.7 +/- 1.7% (p …

Photosensitivity and second harmonic generation in chalcogenide arsenic sulfide poled glasses

2011

International audience; The present work investigates the photoinduced Second Harmonic Generation processes in thermally poled arsenic sulfide glasses. SHG Maker fringes patterns associated to SHG kinetic measurements about illumination and Raman spectroscopy have been conducted in order to bring new information which confirm the combined influence of charge carriers and mid-range glass structural modification on the poling and the photodarkening mechanisms.

Chalcogenide Glasses Based on Germanium Disulfide for Second Harmonic Generation

2007

International audience; High second-order susceptibilities are created by thermal poling in bulk germanium disulfide based chalcogenide glasses. Experimental conditions of the poling treatment (temperature, voltage, time) were optimized for each glass composition. The second-order nonlinear signals were recorded by using the Maker fringes experiment and a second-order coefficient χ(2) up to 8 pm V-1 was measured in the Ge25Sb10S65 glass. This value is obtained using a simulation based on accurate knowledge of the thickness of the nonlinear layer. Two mechanisms are proposed to explain the creation of a nonlinear layer under the anode: the formation and the migration of charged defects towar…