2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/107816We present a stability analysis of a modified nonlinear Schroedinger equation describing the propagation of ultra-short pulses in negative refractive index media. Moreover, using methods of quantum statistics, we derive a kinetic equation for the pulses, making it possible to analyze and describe partial coherence in metamaterials. It is shown that a novel short pulse soliton, which is found analytically, can propagate in the medium.6 pages, 2 figures, to appear in Phys. Rev. EPattern Formation and SolitonsOpticstext