Nasraldien A Eashag Saeed * et al. (IJITR) INTERNATIONAL JOURNAL OF INNOVATIVE TECHNOLOGY AND RESEARCH Volume No.5, Issue No.6, October - November 2017, 7665-7669. 2320 –5547 @ 2013-2017 http://www.ijitr.com All rights Reserved. Page | 7665 Multiscroll Attractors in Semiconductor Laser by Optical Feedback and Direct Current Modulation NASRALDIEN. A. EASHAG SAEED Physics Dept, College of Education Nyala University Nyala, Sudan Sudan University of Science and Technology, Khartoum Sudan A. M. AWADELGIED Karary University Khartoum Sudan Sudan University of Science and Technology, Khartoum Sudan S.F. ABDALAH CNR-Istituto Nazionali di Ottica Largo E. Fermi 6,50125 Firenze, Italy K.A. AL NAIMEE CNR-Istituto Nazionali di Ottica Largo E. Fermi 6,50125 Firenze, Italy Department of physics, College of Science, University of Baghdad, Baghdad, Iraq Abstract: Chaotic behavior with multiscroll attractors and equilibrium points of semiconductor laser dynamics subjected to optical delay feedback and sinusodial injection current modulation observed numerically. The complicated dynamical behavior performed based on numerical simulation of modified Lang-Kobayashi model with direct current modulation term. The results reveal different dynamical regimes involving steady state, periodic, quas-periofdic, mixed modes, chaotic state with high power and 1-D 10 scrll attractors. These dynamics analyzed by sequences of observation analysis, FFT, phase portrait in two and three dimensions that qualify sensitivity of the system to initial conditions and give measure of the rate at which the trajectories separate one from the other(fixed point attractor). These prove important use in Chaos synchronization and networks. Keywords: Semiconductor Laser Nonlinear Dynamics; Time Delay Optical Feedback; Modulation; I. INTRODUCTION Chaos generation and control in nonlinear differential equations and devices to reach such dynamical behavior have been proposed. Among these is semiconductor laser. From the point of view of nonlinear dynamics and chaos generation are very sensitive to external perturbations as a nonlinear interaction of the light with laser medium which can be utilized to stabilize or destabilize semiconductor laser dynamics. These dynamics of semiconductor lasers are formulated by nonlinear system differential equations. Depending on the types of optical feedback, optical feedback strength, external cavity length and injection current [1], many nonlinear dynamical phenomena are occurred, such as multistability [2], instability, selfpulsation [3] and coherence collapse. The output power displays, steady state, regular and irregular oscillations separated by different time intervals with sudden dropouts high chaotic spiking, strange chaotic attractor [4]. Recently, different shapes of chaotic attractors have been generated in different successful methods reported in [5]-[8], one type is multiscroll chaotic attractors which are very much high complex dynamical behavior and classified into 1-D, 2-D, and 3-D scroll attractors, depending on the location of the equilibrium points in the state space [9].These perturbations have been received considerable theoretical and practical attraction involving optical delay feedback from distant mirror or optical fiber loop mirror [10], phase-conjugate feedback [11], optoelectron feedback [12], optoelectron feedback and modulation [13][14], optical injection [15]. These complex behaviors of chaotic attractors are used in great applications such as secure optical communication where confidential information embedded [16], chaotic lidars, random number generation and neural science [17]. In the following we investigate the effect of optical feedback strength in semiconductor laser dynamics. The model of coupled time delay differential equations for the rate of change of electric field amplitude, the carrier density and the optical phase. The model is referred to Lang and Kobayashi [18]. Depending on the modulation parameters and the internal laser parameters, the lasers exhibit complex chaotic behavior [19-20]. II. DYNAMICAL MODEL AND METHOD In the case of a tow –dimensional dynamical system where chaotic dynamics cannot and for small-moderate and strong optical feedback strength; the dynamical model in [18] can be expressed in polar coordinates as: (2.1) )). - (t - (t) - cos(w ) - )E(t + (k + ]E 1/ - [G(t) 1/2 = dE/dt p        (2.2) )). - (t - (t) + sin( )/E - )E(t + (k - ] 1/ - [G(t) /2 = dE/dt p         (2.3) . | E(t) | G(t) - N - /e = dN/dt 2 c   Where E stand for electric field amplitude, N is the carrier density, is optical phase ,optical gain G(t) = . In numerical simulation matlab we consider the initial conditions and parameters