Wave propagation of nonlinear modes and formation of bubble in a two-component helicoidal lattice C. B. Tabi, A. Mohamadou and T. C. Kofané Eur. Phys. J. D, 50 3 (2008) 307-316 Published online: 12 December 2008 DOI: 10.1140/epjd/e2008-00237-5