Secondary bifurcations and transverse standing-wave patterns in anisotropic microcavity lasers close to the first laser threshold

It is well known that in a laser—in the limit of an infinite extent of the transverse aperture—traveling tilted waves are excited at the laser threshold for positive detuning between the frequency of the gain maximum of the active medium and the cavity frequency [Phys. Rev. A 45, 8129 (1992)]. However, a transverse standing wave is unstable. In this paper, it is shown that in anisotropic lasers there can be a chain of secondary bifurcations very close to threshold, which stabilizes the standing wave and then destabilizes it again through a supercritical Hopf bifurcation. The parameter dependence of these bifurcations is discussed. The investigations are motivated by interest in pattern formation in vertical-cavity surface-emitting lasers in which the rotational symmetry is broken due to the dependence of the reflectance of the Bragg reflectors on the polarization vector of the field. The applicability of the results to other class-B lasers is discussed.