Two-color self-similar laser beams in active periodic structures with Pt-symmetry and quadratic nonlinearity

Active nonlinear periodic structures with PT symmetry are characterized by the presence of both absorption and amplification of optical radiation. Quadratic nonlinearity and Bragg reflection in such periodic structures can lead to the formation of two-color solitons. Based on four coupled nonlinear Shredinger equations, we numerically investigate self-similar propagation of laser radiation under second harmonic generation in active periodic structures. We consider the beams with finite width in transverse direction. We study the influence of incident beam width on reflection/propagation properties of active periodic structure. In our research, we consider cases of single and double Bragg resonance on fundamental and second harmonic frequency.