Vertical cavity surface-emitting lasers operating with multiple photonic crystal defect cavities.

摘要

Coherently coupled arrays of vertical cavity surface emitting lasers (VCSELs) offer the potential of extended area coherent sources with high spectral purity, useful in a variety of applications in the high power (laser radar, optical communications, steerable sources) and low power (image processing, spectroscopic sensing, optical logic) regimes. A recently developed method for providing optical confinement is the introduction of a two-dimensional photonic crystal (PhC) pattern with a defect, etched into the top distributed Bragg reflector, to define a defect cavity in a VCSEL. This dissertation investigates the operation of PhC VCSELs that have multiple defect cavities to form arrays of vertically emitting lasers. A major achievement of this work is coherent coupling between the defect cavities, with both out-of-phase and in-phase coherent coupling in 2x1 and 2x2 defect cavity arrays. A qualitative and quantitative understanding of the optical characteristics of PhC VCSEL arrays was developed and demonstrated by the agreement of simulated to experiment results. Other conclusions that are supported by this study are: (1) different wafers result in coupling at different overlap integral values; (2) coupling can be effected by thermal effects (hysteresis observed), and (3) the relative phase difference between the defect civilities can be varied with injection current during both continuous-wave and pulsed operation.