Transverse-mode control in GaN-based laser diodes

Transverse mode in GaN-based violet laser diodes for both vertical and horizontal directions was investigated. In order to achieve stable fundamental mode operation in vertical direction, thick AlGaN contact layer is found to be effective. For the stabilization of a transverse-mode in horizontal direction of the conventional ridge-waveguide structure, it is necessary to precisely control the remaining thickness of p-AlGaN cladding layer. In comparison, inner stripe structure using AlGaN current blocking layer has wide feasibility of the device parameter, excellent stability of large optical confinement, and small aspect ratio of beam divergence, under the condition of the precise control of the AlN molar fraction in AlGaN current blocking layer.