Analysis of Y-junction and coupled laser arrays.

We demonstrate that a recently developed reformulation of the beam propagation method can be employed to give the exact modal structure of infinite Y-junction laser arrays. Our results for realistically short ( asymptotically equal to50-microm) Y-junction lengths are similar to those of previous approaches based on perfect Y-junction arrays. However, we find a previously unreported anomalous behavior for the gain of some higher-order supermodes. We also study short and weakly guiding nonideal Y-junction laser arrays. We then describe the behavior of coupled laser arrays in terms of band structure and subsequently propose a new high power strongly coupled laser array configuration.