Personne :
Galstian, Tigran

Photo de profil
Adresse électronique
Date de naissance
Projets de recherche
Structures organisationnelles
Fonction
Nom de famille
Galstian
Prénom
Tigran
Affiliation
Département de physique, de génie physique et d'optique, Faculté des sciences et de génie, Université Laval
ISNI
0000000116613117
ORCID
Identifiant Canadiana
ncf11857328
person.page.name

Filtres

2002 - 20054
4
4
4
Réinitialiser les filtres

Paramètres

Sujet: Polarisation (Lumière) ×

Résultats de recherche

Voici les éléments 1 - 4 sur 4
  • Publication
    Restreint
    Bifurcation analysis of optically induced dynamics in nematic liquid crystals : circular polarization at normal incidence
    (Optical Society of America, 2005-08-01) Brasselet, Étienne.; Galstian, Tigran; Dubé, Louis J.; Dmitry, Krimer; Kramer, Lorenz
    We present a detailed bifurcation analysis of the nonlinear reorientation dynamics of a homeotropically aligned nematic liquid-crystal film excited by an elliptically polarized beam at normal incidence with the intensity and the polarization state of light as the control parameters. The asymmetry arising from the elliptical polarization of the excitation lightwave is shown to affect dramatically the dynamics, and various new dynamical behaviors are reported: (i) quasi-periodic rotations for almost circular polarization; (ii) a discontinuous transition, identified as a homoclinic bifurcation, to a largely reoriented state over a large range of ellipticity values; (iii) oscillations associated with large reorientation; and (iv) optical multistability between several distinct dynamical regimes.
  • Publication
    Restreint
    Bifurcation analysis of optically induced dynamics in nematic liquid crystals : elliptical polarization at normal incidence
    (Optical Society of America, 2005-08-01) Krimer, Dmitry; Brasselet, Étienne.; Kramer, Lorenz; Galstian, Tigran; Dubé, Louis J.
    We present a detailed bifurcation analysis of the nonlinear reorientation dynamics of a homeotropically aligned nematic liquid-crystal film excited by an elliptically polarized beam at normal incidence with the intensity and the polarization state of light as the control parameters. The asymmetry arising from the elliptical polarization of the excitation lightwave is shown to affect dramatically the dynamics, and various new dynamical behaviors are reported: (i) quasi-periodic rotations for almost circular polarization; (ii) a discontinuous transition, identified as a homoclinic bifurcation, to a largely reoriented state over a large range of ellipticity values; (iii) oscillations associated with large reorientation; and (iv) optical multistability between several distinct dynamical regimes.
  • Publication
    Accès libre
    Optically induced dynamics in nematic liquid crystals : the role of twist deformation and asymmetry
    (American Physical Society, 2003-03-26) Brasselet, Étienne.; Galstian, Tigran; Dubé, Louis J.; Doyon, Bernard
    We present a theoretical study of optically induced dynamics in a homeotropic nematic liquid crystal excited at normal incidence. By retaining the first symmetric and antisymmetric reorientation modes, the dynamical equations are reduced to a four-dimensional problem. The main advantage of this minimal approach is to emphasize the role of twisted mode and asymmetry of the light-induced molecular reorientation in a manner suitable for a clear physical interpretation. Theoretical results are compared with experiments in the particular case of circularly polarized light beams to show the physical origin of mode competition and of the breakdown of chiral and longitudinal symmetry. The model successfully describes previous experimental studies such as time-dependent three-dimensional molecular dynamics, light-induced stabilized helical reorientation, and in-plane precession regime in achiral nematics. While a recent experiment has revealed a new spatiotemporal transition, the model succeeds to describe all the features of such a bifurcation pointing out anew the importance of asymmetry. Finally, the first quantitative description of the appearance of a giant mirrorless optical bistability when twisted reorientation modes are excited is demonstrated. A qualitative physical interpretation is suggested for all these phenomen
  • Publication
    Restreint
    New laser induced spatio–temporal transition in nematics
    (Elsevier Science, 2002-05-07) Brasselet, Étienne.; Galstian, Tigran; Dubé, Louis J.; Doyon, Bernard
    We report the observation of a new light-induced spatio–temporal transition in homeotropically aligned nematic liquid crystals under the action of circularly polarized light. We believe that the competition of symmetric and asymmetric excitation modes is at the origin of this abrupt transition. A theoretical model explaining the main features of the observation is proposed