Theoretical Study of Tunable Optical Resonators in Periodic and Quasiperiodic One-Dimensional Photonic Structures Incorporating a Nematic Liquid Crystal

Youssef. Trabelsi,Naim. Ben Ali,Arafa H. Aly,Walid. Belhadj

doi:10.3390/photonics8050150

Abstract

In this work, the transfer matrix method (TMM) is employed to investigate the optical properties of one-dimensional periodic and quasiperiodic photonic crystals containing nematic liquid crystal (NLC) layers. This structure is expressed as (ABC)J(CBA)J and made of alternated layers of isotropic dielectrics SiO2 (A), BGO (B) and nematic liquid crystal (C). The simulation study shows that the proposed ternary configuration exhibits tunable defect mode within the photonic band gap (PBG) that can be manipulated by adjusting the thicknesses of NLC layers in order of the periodic lattice. In addition, the optimized structure permits for strong confinement light giving rise to an optical microcavity. The application of an applied voltage into NLC layers enables improving the sensitivity by guiding the local defect mode. It has been also shown that by applying quasiperiodic inflation according to Rudin Shapiro Sequence (RSS) scheme to main periodic structure, several tunable resonant modes appear within the PBG. The presence of such sharp resonant peaks reflects that the quasiperiodic NLC-based structure behaves like multiple microcavites with strong light-matter coupling.

Highlights

Photonic crystals (PCs) discovered by Yablonovitch in 1987 [1] are artificial composites of insulating or metallic materials
We will employ the transfer matrix method (TMM) approach to investigate the spectral behaviors of 1D NLCbased photonic structures versus parameters related to nematic liquid crystal (NLC) constituent layers such as thickness, tilt angle and applied voltage
The layer C corresponds to the nematic liquid crystal (NLC) with ordinary and extraordinary refractive indices no = 1.500 and ne = 1.689, respectively [44]

Summary

Introduction

Photonic crystals (PCs) discovered by Yablonovitch in 1987 [1] are artificial composites of insulating or metallic materials. Intensive studies used quasicrystals and photonic amorphous materials instead of ordinary PC in order to improve the performance of an optical devise [14,15,16] It opens structural microcavities within the main PBG, which improves the photonic band gap properties [17]. The planar Nematic LC is extensively used as a central defect into one-dimensional (1D) PCs due to its ability to obtain a tunable Photonic bang gap (PBG) This type of hybrid LC-Photonic crystals exhibits an excellent ability to control the propagation of light modes. To improve the confinement of light by open multiple microcavities, multilayered stacks with constituents arranged according to Rudin Shapiro Sequence (RSS) scheme is followed

Theoretical Model

Result and Discussion

Findings

Conclusions