No abstract

No abstract

No abstract

A model for a non-Kerr cylindrical nematic fiber is presented. We use the multiple scales method to show the possibility of constructing different kinds of wavepackets of transverse magnetic (T M ) modes propagating through the fiber. This procedure allows us to generate different hierarchies of nonlinear partial differential equations (P DEs) which describe the propagation of optical pulses along the fiber. We go beyond the usual weakly nonlinear limit of a Kerr medium and derive a complex modified Korteweg-de Vries equation (cmKdV) which governs the dynamics for the amplitude of the wavepacket. In this derivation the dispersion, self-focussing and diffraction in the nematic are taken * Fellow of SNI, Mexico † Correspondence author. E-mail: zepeda@fisica.unam.mx ‡ Fellow of SNI, Mexico 1 into account. It is shown that this cmKdV equation has two-parameter families of bright and dark complex solitons. We show analytically that under certain conditions, the bright solitons are actually double embedded solitons. We explain why these solitons do not radiate at all, even though their wavenumbers are contained in the linear spectrum of the system. We study (numerically and analytically) the stability of these solitons. Our results show that these embedded solitons are stable solutions, which is an interesting property since in most systems the embedded solitons are weakly unstable solutions. Finally, we close the paper by making comments on the advantages as well as the limitations of our approach, and on further generalizations of the model and method presented.

No abstract

No abstract

Using the equilibrium configuration adopted by a cholesteric elastomer elongated by the influence of a uniaxial transverse stress, the authors calculate the solution of the boundary-value problem for the reflection and transmission of obliquely incident plane waves due to a elastomer slab. The authors find a left-circularly polarized thin reflection band immersed in a wider right-circularly polarized band reflection when the elastomer is under a stress near to the critical value. Also, a deformation of the reflection band and the reduction of its bandwidth were obtained. These band gap features suggest to design a finely tuning polarization-universal optical filter.

No abstract