Bifurcation analysis of optically induced dynamics in nematic liquid crystals : circular polarization at normal incidence

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.