2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/148621We study the propagation of radiation through a disordered waveguide with a complex dielectric constant $ε$, and show that dual systems, which differ only in the sign of the imaginary part of $ε$, have the same localization length. Paradoxically, absorption and stimulated emission of radiation suppress the transmittance of the waveguide in the same way.Added a reference to the paper by Z.Q. Zhang, Phys.Rev.B. 52, 7960 (1995)Condensed Mattertext