Search results for "Poling"
showing 10 items of 63 documents
Poling dynamics of an EO active material using parallel-plate electrodes
2017
We describe the sample preparation and experimental setup for second harmonic generation measurement of electro-optical (EO) chromophore/polymer system at the time of contact-poling. Different types of spacers for avoiding electric breakdown due to avalanche multiplication are compared. Electric field threshold values for second harmonic generation are observed in all samples.
Insight in NLO Polymer Material Behavior from Langevin Dynamic Modeling of Chromophore Poling
2011
Calculation of chromophore polar order, i.e. the polarization of nonlinear optically (NLO) active polymers poled by external field, is challenging. One possible solution is to reproduce the orientation polarization of chromophores under external field using Langevin dynamics (LD) molecular modeling. The present work investigates the influence of chromophore dipole moment, density and field extent on NLO efficiency and polarization/relaxation dynamics. Results of simulations convince us, that the method is applicable for modeling real NLO polymers. In the spotlight of this investigation we would like to describe a NLO polymer as a “ferrofluid” where chromophores are active particles or elect…
Stability of the functional NLO polymers–optically induced depoling of the DMABI molecules in sPMMA matrix
2008
Abstract Low polar order (PO) stability is the major problem of the polymer materials for nonlinear optical (NLO) applications. In this contribution we will show the results of PO stability investigations in the corona poled 3 wt.% DMABI + sPMMA guest–host system. Influence of the poling temperature on the building and stability of the polar order in the system will be presented. To characterize the stability, PO destruction has been caused by high intensity light. Polar order stability characteristics were obtained from the sample second harmonic generation intensity (SHI) time decays. We have found that the decay signal is the best fit to the sum of two exponentials. Several physical mode…
<title>All-optical poling of DMABI molecules in a polymer matrix</title>
2005
Many organic compounds in solid state have nonlinear optical properties due to the orientation of the molecules in a polymer matrix. In this work, all-optical poling and second harmonic generation in a composition consisting of 1 mass% of N,N-dimethylaminobenzylidene 1,3-indandione (DMABI) compound in poly(methyl methacrylate) (PMMA) matrix were studied. Thin films were prepared by solvent casting. The 1.064-μm fundamental and 532-nm second harmonic wavelengths of a Nd:YAG laser were used. It is shown that DMABI molecules can be oriented by the method of all- optical poling, and that the process is related to the photoinduced switching between two equally stable states of the molecule.
Surface periodic poling in congruent lithium tantalate
2006
The first demonstration of surface periodic poling of lithium tantalate at high voltages is reported. Periodic domain inversion with mark-to-space ratios close to the optimum 50:50 was successfully achieved down to micrometre periods with good uniformity and repeatability.
Représentations touristiques et corps féminin: les placards publicitaires des vacances en croisières
2011
Cette étude analyse l’image de la femme dans les placards publicitaires des croisières. Ces images sont remarquables pour deux raisons. D’abord elles montrent les aspects socioculturels qui tournent autour de l’image féminine dans le tourisme en posant des réflexions épistémologiques sur le féminisme. Ensuite elles utilisent des stratégies sémiotiques et linguistiques qui jouent un rôle fondamental dans la mise en désir des destinations touristiques. Dans cette recherche, nous nous proposons de souligner l’importance d’une approche anthropologique, sémiotique et linguistique d’un placard publicitaire sur les croisières. Nous analysons largement la fonction de la sexualité féminine par l’ima…
Contribution and effectiveness of ski and pole forces in selected roller skiing techniques on treadmill at moderate inclines
2023
BackgroundMost of the studies about the effects of incline on cross-country skiing are related to the metabolic efficiency. The effective skiing biomechanics has also been indicated to be among the key factors that may promote good performance. The aims of this study were to provide biomechanical characteristics and investigate the relative contribution and effectiveness of ski and pole forces in overcoming the total external resistance with double poling (DP) and Gear 3 (G3) techniques at varying moderate uphill inclines.Methods10 male cross-country skiers participated in this study. Custom-made force measurement bindings, pole force sensors, and an 8-camera Vicon system were used to colle…
Propulsion Calculated by Force and Displacement of Center of Mass in Treadmill Cross-Country Skiing
2022
This study evaluated two approaches for estimating the total propulsive force on a skier’s center of mass (COM) with double-poling (DP) and V2-skating (V2) skiing techniques. We also assessed the accuracy and the stability of each approach by changing the speed and the incline of the treadmill. A total of 10 cross-country skiers participated in this study. Force measurement bindings, pole force sensors, and an eight-camera Vicon system were used for data collection. The coefficient of multiple correlation (CMC) was calculated to evaluate the similarity between the force curves. Mean absolute force differences between the estimated values and the reference value were computed to evalua…
Nonlinear Disorder Mapping Through Three-Wave Mixing
2010
We implement a simple and powerful approach to characterize the domain distribution in the bulk of quadratic ferroelectric crystals via far-field second-harmonic spectroscopy. The approach is demonstrated in a lithium tantalate sample with periodic electric field poling and random mark-to-space ratio.
Ski economy and physiological responses while double poling : curved vs. straight poles
2015
Christina Mishica (2015). Ski economy and physiological responses while double poling: curved vs. straight poles. Department of Biology of Physical Activity, University of Jyväskylä, Master’s Thesis in Exercise Physiology. 57 pp. Introduction. Double poling (DP) is commonly used in cross country skiing (XC). It is becoming more and more popular and in some competitions it is the exclusive technique. Ski poles allow a skier to apply power and force to the snow and their composition and design have a significant effect on performance. Different pole lengths and cross sections are some of the differences that have been tested. Advancements in equipment will continue to be introduced so it is i…