Microsoft Word - 04-3455_s_ETASR_V10_N3_pp5603-5607 Engineering, Technology & Applied Science Research Vol. 10, No. 3, 2020, 5603-5607 5603 www.etasr.com Bouazzi et al.: Computational Modeling of Quasi-Periodic Rudin-Shapiro Multilayered Band Gap … Computational Modeling of Quasi-Periodic Rudin- Shapiro Multilayered Band Gap Structure Yassine Bouazzi Industrial Engineering Department University of Hail Hail, Saudi Arabia yassine.bouazzi@enit.utm.tn Naim Ben Ali Industrial Engineering Department University of Hail Hail, Saudi Arabia naimgi2@yahoo.fr Haitham Alsaif Electrical Engineering Department University of Hail Hail, Saudi Arabia hal-saif@hotmail.com Attia Boudjemline Industrial Engineering Department University of Hail Hail, Saudi Arabia a_boudjemline@hotmail.com Youssef Trabelsi Physics Department King Khalid University Aseer, Saudi Arabia youssef_trabelsi@yahoo.fr Ahmed Torchani Industrial Engineering Department University of Hail Hail, Saudi Arabia tochahm@yahoo.fr Abstract—The optical transmission spectra proprieties of the one- dimensional quasi-periodic multilayered photonic structures according to the Rudin-Shapiro distribution are studied theoretically in this paper by using a theoretical model based on the transfer matrix approach for normal incidence geometry. The influence of the layer number has been studied, i.e. the iteration order of the generating sequence of the quasi-periodic structure on the structure spectral behavior and the width of the Photonic Band Gap (PBG). It was found that the width of the PBG is proportional to the index contrast. Keywords-photonic crystal; Rudin-Shapiro distribution; transfer-matrix method; transmittance; photonic band gap I. INTRODUCTION Photonic crystals are new, artificially created materials in which the refractive index is periodically modulated in a scale compared to the wavelength of operation [1-4]. In fact, the periodic modulation of the refractive index of such a structure causes the appearance of frequency ranges for which the light cannot propagate [5]. Photonic crystals at the end of the last century became one of the most active research topics in various technological disciplines, e.g. communications, optoelectronics, and optics [6, 7]. The simplest form of a photonic crystal is the one-dimensional periodic structure, known as the Bragg mirror. It consists of a stack of alternating layers with low and high refractive index and a thickness in the order of ��/4, where �� is the reference wavelength, i.e. the thicknesses satisfy the Bragg condition. There is currently a need to design photonic materials with broader band gaps and multiband. The first manifestation of this goal was the realization of a new class of artificial crystals, called quasi- periodic photonic crystals [8]. These structures are formed by the stacking of two or more deposited materials according to a predefined recursive inflation rule, so that they can be considered as intermediate systems between an ordinary periodic crystal and random amorphous solids. These quasi- periodic structures have become the subject of intense research. They have led to many technological achievements in the fields of photonics, telecommunications, and microwaves [9]. This paper aims to study the optical properties of the photonic quasi-periodic unidimensional multilayer structures from their spectral response using theoretical modeling and numerical simulation based on the Transfer Matrix Method (TMM). II. MODELING PROCEDURE AND NUMERICAL SIMULATION A. Structure Presentation The Rudin-Shapiro sequence, also known as the Golay- Rudin-Shapiro sequence, is an infinite automatic sequence [10, 11] introduced in 1950 [12]. Rudin-Shapiro's 1D multilayered distribution system was exploited for the first time to study light confinement in multilayer structures in 2008 [13]. The Rudin-Shapiro sequence can be defined by [14-15]: RS(�) = ����� ...ε� ...ε�����. (1) with: �� = (−1)�(�) (2) where u(i) represents the number “11” in the binary development of the integer i. The use the Rudin-Shapiro distribution in the photonics field remains very limited due to the construction peculiarity of this structure. It is represented by quaternary elementary layers (A, B, C and D) with substitution rules given by: � As={A, B, C, D} → AB, B → AC, C → DB, D → DC (3) Corresponding author: Yassine Bouazzi Engineering, Technology & Applied Science Research Vol. 10, No. 3, 2020, 5603-5607 5604 www.etasr.com Bouazzi et al.: Computational Modeling of Quasi-Periodic Rudin-Shapiro Multilayered Band Gap … The generation starts with the element labeled by the letter A. For example, a multilayer structure of iteration order 2 is given by: S2 ACAB, order 3 by S3 ACABACDC… (Figure 1). Table I presents the generation of the structure of iteration order k=1,2,3. TABLE I. THE FIRST GENERATIONS OF THE 1D MULTILAYER STRUCTURE ACCORDING TO THE RUDIN-SHAPIRO DISTRIBUTION Iteration order Alphabetic sequence RS(0) A RS(1) AC RS(2) ACAB RS(3) ACABACDC In this work, we chose a multilayer photonic system composed of four dielectric layers A, B, C and D, distributed according to the Rudin-Shapiro sequence, having refraction indices �" , �# , �$ and �% , and optical thicknesses ��/n" , ��/n# , ��/n$ and ��/n% respectively, where �� is the reference wavelength. Furthermore, the optical and geometrical parameters of the structure obey the quarter wavelength condition or Bragg condition as indicated by (4): �"'" �#'# �$'$ �%'% ()* (4) Fig. 1. One-dimensional Rudin-Shapiro multilayer dielectric structure for the 3 rd iteration RS(3): ACABACDC B. Simulation Method For the calculation of reflection and transmission, we used TMM, which is a technique well suited to the study of PBG materials. This technique can solve the standard problem of the photonic band structures to find transmission, reflection, and absorption spectra. This method consists in expressing the reflected field +,-�� from a multilayer structure as a function of incident fields +,-�. in a matrix form. The studied multilayer structure consists of a stack of m layers with different thicknesses '� and refractive indices ��, as shown in Figure 2. The amplitudes of the electric fields of incident and transmitted wave are expressed by the following matrix for stratified films within m layers: /+�.+�� 0 = ∏ 234.�� /+4.� .+4.�� 0 (5) where 23 is the propagation matrix for the jth layer, given by: 23 = 5 �67 exp ��;<3�� =767 exp �;<3�� =767 exp ��;<3�� �67 exp ��;<3�� > (6) where