Phase tuning in two-dimensional coherently coupled vertical-cavity surface-emitting laser array

Abstract

Implant-defined vertical-cavity surface-emitting laser (VCSEL) arrays can be designed to operate in in-phase mode. However, the nonuniformities in fabrication process impact the resonance selection and the devices do not follow expected trends. Coherent coupling was demonstrated in three-element VCSEL arrays via phase tuning of elements. In-phase mode and out-of-phase mode were both achieved in most of the arrays. Moreover, coherent coupling can decrease the threshold current of elements in the array. Improved output power was also clearly observed when the array operated in the in-phase mode. Arbitrary phase combination of the array elements can be obtained via the phase tuning. This technology is able to improve the reproducibility and practicability of the implant-defined coherently coupled VCSEL array.