Gómez Calderón, ÓscarGonzalo Fonrodona, Isabel2023-06-202023-06-201998-031050-294710.1103/PhysRevA.57.2056https://hdl.handle.net/20.500.14352/59546© 1998 The American Physical Society. We are very grateful to J. M. Guerra for his helpful advice. This work was supported by the DGICYT Project No. PB95-0389 (Spain).Transverse effects in the laser threshold, originated by electronic-vibrational coupling in the active centers, are analyzed theoretically by means of the semiclassical two-level Maxwell-Bloch equations. A single longitudinal mode is considered. It is found that the first laser threshold suffers modifications depending on the electronic-vibrational coupling strength. This coupling imposes certain conditions for the selection of a particular transverse spatial state and provides the minimum wavelength that can appear in the transverse pattern. The nature of the bifurcation and the stability of the homogeneous and critical traveling waves are analyzed.engjournal articlehttp://dx.doi.org/10.1103/PhysRevA.57.2056http://journals.aps.org/open access535Homogeneously broadened lasers2-photon optical bistabilityPolymersPatternsDynamicsModesÓptica (Física)2209.19 Óptica Física