Convective instabilities in optical systems with non-local feedback

This work examines a system with nonlocal feedback, a liquid crystal spatial light modulator, with laterally shifted feedback and shows that convective instabilities can be caused by nonlocality. Furthermore, the study shows that the presence of a spatial filter in the system can transform a convective instability into an absolute instability. This role of the filter on the determination of the nature of the instability is a general result that does not depend on the type of nonlinearity.