In-phase supermode operation in GaN-based vertical-cavity surface-emitting laser

A phase-locked ring-array GaN-based vertical-cavity surface-emitting laser (VCSEL) was demonstrated using a floral-patterned structure, based on a buried-SiO2 lateral optical confinement technique. This structure enabled the realization of evanescently coupled waveguides in the circumferential direction with a high differential quantum efficiency of 30%, even in a blue GaN-based VCSEL. A coupled ring array with eight optical spots produced a very narrow divergence beam of 2.8° with an on-axis far-field emission. These results, together with single-longitudinal-mode operation in the lasing spectrum, provide evidence that the proposed GaN-based VCSEL exhibits in-phase supermode operation.