Search results for " Polarization"
showing 10 items of 668 documents
Field-free one-dimensional alignment of ethylene molecule
2006
International audience; We report an experimental study of non-adiabatic laser-induced molecular alignment of ethylene (C2H4) using a linearly polarized short laser pulse of moderate intensity. The information about the confinement of the C=C bond axis along the direction of the applied electric field is obtained by measuring the depolarization of a second short pulse of weak intensity interacting with the molecules after they have been exposed to the first pulse. The experimental data are compared with the numerical simulation of the Schr¨odinger equation written for the non-resonant interaction of an asymmetric top rigid rotor with a linearly polarized electric field. The field-free align…
Field-free molecular alignment induced by elliptically polarized laser pulses: Noninvasive three-dimensional characterization
2007
International audience; An investigation of field-free molecular alignment produced by elliptically polarized laser pulses is reported. Experiments are conducted in CO2 at room temperature. A noninvasive all-optical technique, based on the cross defocusing of a probe pulse, is used to measure the alignment along two orthogonal directions which is sufficient to provide a three-dimensional characterization. The field-free molecular alignment produced by a laser of elliptical polarization is in good agreement in terms of amplitude and shape with theoretical predictions. It turns out to be almost equivalent to the superposition of the effects that one would obtain with two individual cross-pola…
Statistical analysis of pulse propagation driven by polarization-mode dispersion
2002
International audience; The linear propagation of pulses driven by random polarization-mode dispersion is considered. Analytical expressions are derived for the probability-density functions of the pulse width, timing displacement, and degree of polarization. The study is performed in Stokes space, and frequency correlation between modes is shown to play an important role in it.
Integrated low drive voltage electro-optic Bragg modulator using a, periodically poled lithium niobate
2017
Periodically poled lithium niobate (PPLN) is currently used for frequency conversions using quasi-phase-matching, thanks to its high nonlinear coefficients and mature poling process. PPLN can also be attractive for electro-optic (EO) applications. Several studies have been conducted on PPLN-based EO deflectors, and recent realizations have lower the required applied voltage under hundred volts [1]. Indeed, for practical EO applications drive voltages as low as 5 V are usually required. For this purpose, we use a recent technique to realize high-quality isolated crystalline film out of LN [2] to implement an EO Bragg deflector with a drive voltage below 10 V. In this work we present an effic…
Demonstration of polarization pulling in a fiber-optical parametric amplifier
2012
International audience; We report the experimental demonstration of all-optical polarization pulling of an initially polarization-scrambled signal using a fiber-optical parametric amplifier. Nonlinear polarization pulling has been achieved for both the signal and idler with 25 dB gain.
Observation of light-by-light polarization control and stabilization in optical fibre for telecommunication applications
2010
International audience; In many photonics applications, especially in optical fibre based systems, the state of polarization of light remains so far an elusive uncontrolled variable, which can dramatically affect the performances of that systems and which one would like to control as finely as possible. Here, we experimentally demonstrate light-by-light polarization control via a nonlinear effect occurring in single mode optical fibre. We observe a polarization attraction and stabilization of a 10 Gbit/s optical telecommunication signal around 1550 nm. We also validate the potentiality of the device to annihilate very fast nanosecond polarization bursts. This result confirms yet another fas…
Single crystal EXAFS at high pressure
2000
Abstract We present a new technique for structure characterization under high pressure conditions. The use of an undulator beam of the third-generation ESRF source of synchrotron radiation has enabled the first single crystal EXAFS experiments at high pressure using a diamond anvil cell as pressure generator. Taking advantage of the linear polarization of X-rays the technique becomes an orientation-selective probe of the local structure of materials. We describe the principle of the technique and some applications.
3D acquisition system for transparent objects
2010
This thesis deals with a new automated tridimensional inspection system for transparent surfaces, based on polarization analysis. We first present an extension of the ‘Shape from Polarization’ method for transparent surfaces. After being reflected, an unpolarized light wave becomes partially linearly polarized, depending on the surface normal and on the refractive index of the media it impinges on. Hence, by measuring the polarization parameters of the reflected light, the surface normals are computed. The ambiguity concerning the normal orientation is solved here with a multispectral lighting system. Finally, the description of the whole acquisition prototype is given as well as some exper…
Sport and Quality of Life
2022
Negli ultimi trent’anni lo sport ha assunto un significato molto rilevante nella vita delle persone e, seppure con notevoli differenze, sia nei paesi a sviluppo economico avanzato, sia in quelli in via di sviluppo. A livello individuale, esso ha costituito un’area di investimento identitario quando ha assunto la forma di sport spettacolo del quale fruire, alimentando la pratica del tifo e il fandom o costituendo il modello di uno stile di vita vincente; ma anche quando ha assunto la forma di pratica del tempo libero attraverso la quale tenersi in forma, facendo crescere, in questo caso, la diffusione di una cultura della salute e del benessere. Si tratta di due modalità di approcciare al co…
DC01 steel corrosion resistance in cathodic polarization
2016
Celem prowadzonych badań było okreœlenie odporności korozyjnej stali DC01 poddanej katodowej polaryzacji w zmiennych warunkach. Elektrochemiczne pomiary służące do oceny odpornoœci korozyjnej stali nienawodorowanej poddanej katodowej polaryzacji przeprowadzono metodami obejmującymi pomiar potencjału obwodu otwartego i zarejestrowania zależności i=f(E) podczas badań polaryzacyjnych w trójelektrodowym układzie pomiarowym. Do pomiarów wykorzystano układ składający się z naczynka pomiarowego, potencjostatu AMEL PSW01 System 5000 oraz komputera z oprogramowaniem „CorrWare”. Wodorowanie stali zrealizowano w wodnym roztworze 0,1 N kwasu siarkowego(VI) z dodatkiem 2 mg/dm3 tlenku arsenu(III) jako p…