Composite vector solitons with topological charges and their stability analysis Jiandong Wang, Fangwei Ye, Liangwei Dong, Tian Cai, Yong-Ping Li Department of physics of university of science and technology of China, Hefei, 230026, China ABSTRACT The existence and stability properties of three-component vector solitons are studied. Linear stability analysis and numerical simulations show that when the power of vortex component is below a threshold, the fundamental component is stable, and the vortex components break up into dipole solitons; the dipole solitons originating from the vector solitons with total zero topological charges are very unique. While if the power of vortex components is higher than that threshold, all soliton components are unstable and break up into independent fundamental solitons. The instability of solitons with total zero topological charges is largely suppressed comparing to that of solitons with total nonzero topological charges. Keywords: solitons, vector solitons, vortex solitons, ring solitons, dipole solitons, composite solitons, topological charges, stability analysis, saturable nonlinearity, NLS. 1. INTRODUCTION Optical solitons were first predicted in 1964 [1], and since then, they have attracted considerable attention especially in recent years due to their promising applications in all-optical devices, in which light guides and steers light itself [2]. Spatial optical soliton is an optical beam which can be viewed as a self-trapped mode of an effective waveguide it induces by itself in a nonlinear medium; therefore, the beam does not spread (owing to diffraction) during propagation. Intuitively, spatial optical solitons represent an exact balance between diffraction and self-focusing effects induced by nonlinearity [3]. There are different types of nonlinearities which can support spatial optical solitons: pure Kerr nonlinearity, saturable nonlinearity, competing cubic-quintic nonlinearity and quadratic or (2) nonlinearity. Various kinds of solitons have been studied: bright fundamental solitons, bright ring (vortex) solitons, and dark solitons. It has been theoretically shown that (1+1)D (one transverse dimension and one propagation dimension) pure Kerr solitons are stable; (2+1)D bright solitons in bulk Kerr medium undergo catastrophic collapse [4]. The stability of fundamental (2+1)D solitons can be achieved in saturable [5] and quadratic [6] nonlinear medium, but they can not support stable vortex solitons [7]. Stable vortex solitons have been realized in the model of competing cubic-quintic or quadratic-cubic nonlinearity [8]. As for dark solitons, detailed analysis can be seen in review paper [9]. Corresponding author: liyp@ustc.edu.cn (Y. P. Li) Tel: +86(0)5513606087 Fax: +86(0)5513601073 Nonlinear Optical Phenomena and Applications, edited by Qihuang Gong, Yiping Cui, Roger A. Lessard, Proceedings of SPIE Vol. 5646 (SPIE, Bellingham, WA, 2005) · 0277-786X/05/$15 · doi: 10.1117/12.571045 6