Simulations of boundary layers and point defects in coupled VCSEL arrays

The inherent gain dependence on carrier depletion and on the lateral cavity interactions differentiates active photonic lattices from passively coupled models, employing a given complex gain profile. This paper addresses coupled vertical-cavity surface-emitting laser array effects due to finite boundaries and the possibility of individual bias failures, of interest for practical applications. The "cold-cavity" characteristic parameters are assumed identical, focusing on biasing defects and site vacancies. Analysis and numerical simulations based on the tight-binding approximation show that phase-locking persists in finite arrays. Self-regulation of the edge cavity density and power generate boundary layers of differentiated cavity operation values. The inter-cavity phase shift remains nearly uniform, with a small superimposed linear slope caused by cross-cavity reflection interference from distributed Bragg reflectors. Phase locking is robust against partial or complete failure to lase for individual cavity sites, or even entire rows, due to biasing errors.