fa Stability of Dark Solitons In PT-symmetric Nonlinear Couplers تخصصی Special پژوهشي Research In this paper we derive analytical dark soliton solutions in a nonlinear PT-symmetric coupler with gain in one waveguide and loss in the other in normal dispersion regime by using perturbation method. The usual solutions of noncoupled equations are dark solitons. Evaluating perturbation analytically shows that perturbations which guaranty the stability are in two forms of bright and dark solitons. However, in systems with the usual solutions of bright solitons, only a bright soliton perturbation satisfies the stability. In this paper we derive analytical dark soliton solutions in a nonlinear PT-symmetric coupler with gain in one waveguide and loss in the other in normal dispersion regime by using perturbation method. The usual solutions of noncoupled equations are dark solitons. Evaluating perturbation analytically shows that perturbations which guaranty the stability are in two forms of bright and dark solitons. However, in systems with the usual solutions of bright solitons, only a bright soliton perturbation satisfies the stability. Nonlinear Optics, Dark Solitons, PT-Symmetric Couplers Nonlinear Optics, Dark Solitons, PT-Symmetric Couplers 1659 1662 http://opsi.ir/browse.php?a_code=A-10-1-784&slc_lang=fa&sid=1 lida safaei lida safaei lida_safaei@yahoo.com 10031947532846003748 10031947532846003748 Yes mohsen hatami mohsen hatami hatami@sutech.ac.ir 10031947532846003749 10031947532846003749 No mahmood borhani zarandi mahmood borhani zarandi mBorhani@yazd.ac.ir 10031947532846003750 10031947532846003750 No