Abstract

We recently presented a coupled-mode theory of the dynamics of semiconductor-laser arrays that showed the existence of certain instabilities in these arrays.¹ An implicit assumption of coupled-mode theory is that of weak coupling between the elements. Under that condition, the individual laser elements retain their identities, and their uncoupled fields form proper basis modes for the coupled-mode description. This approach is strictly correct for index-guided laser arrays, in which a built-in index-guide provides lateral confinement of the mode fields within each laser. In gain-guided lasers, the lateral guiding mechanism is much weaker. For such lasers, as well as the recently demonstrated anti guide arrays, a continuum model may be more appropriate. In this paper we present a self-consistent continuum model for the dynamics of semiconductor-laser arrays. The model is based on the solution of a pair of coupled partial differential equations for the complex field and the carrier density in the array. This model has been applied successfully to both gain-guided and index-guided laser arrays. By varying the center-to-center spacing between the waveguides, we have mapped out regions of stable and unstable temporal behavior in the laser output.

© 1990 Optical Society of America