Asymmetric mode scattering in strongly coupled photonic crystal nanolasers

In semiconductor-coupled micro and nano-cavities, the combination between tight light confinement and high optical nonlinearities open up new routes for the study of light-matter interaction in non-equilibrium driven dissipative systems. Even at the semiclassical level, coupled cavities may display a wide range of rich nonlinear dynamical phenomena such as instabilities and bifurcations. Mode competition is at the heart of multimode laser dynamics, and may occur when different modes share the same gain medium. Mode switching (MS) and bistability have been observed in standard microcavity systems, such as vertical-cavity surface-emitting lasers (VCSELs), micropillar lasers, semiconductor ring lasers. These mechanisms usually rely on symmetric cross-gain saturation effects. However, mode interaction in semiconductor cavities may also be asymmetric, resulting from stimulated scattering due to a dynamic carrier population grating in the gain medium, which oscillates at the beat note frequency between adjacent cavity modes. Such an asymmetric interaction enables energy transfer from the laser mode at the blue side of the spectrum to the mode at the red side.