Tunable transmission of a nematic liquid crystal as defect in a 1D periodic structure of dielectric materials by orientation and re-orientation of liquid crystal molecules.

In this paper, we investigate tunable transmission characteristics of a one-dimensional periodic structure (1DPS), designed with periodic dielectric materials containing a nematic liquid crystal (NLC) as a defect layer, on the basis of orientation and re-orientation of LC molecules. The nonlinear differential equation for the director of the liquid crystal under the light field is solved numerically. The relation between the liquid crystal director and the intensity of the electromagnetic wave (EMW) is derived. Transmittances of the liquid crystal defect layer in the 1DPS are calculated with the variation of the intensity of the incident wave and liquid crystal director tilt angles. By varying the director tilt angle of the liquid crystal molecules as well as the incident angle of the EMW, the shifting of the transmitted defect mode wavelengths is studied. Such study is helpful to understand how orientation and reorientation of the molecules affect the transmittance of the considered periodic structure when the EMW interacts with an embedded liquid crystal as a defect layer in the 1DPS of dielectric materials. Such photonic structure of dielectric materials with the liquid crystal layer as a defect layer can be used to fabricate bistable switches, optical filters, feedback lasers, etc.