Ridge waveguide lasers with vertically stacked quantum wells and tunnel junctions. (1st September 2022) - Fricke, J
Abstract: We report on the fabrication and electro-optical performance of ridge waveguide (RW) lasers emitting near 905 nm based on a vertical layer structure consisting of three single quantum wells (SQWs) as active regions separated by two tunnel junctions (TJs). The single waveguide core is designed in such a way that the third vertical mode is lasing. The width of the ridge is varied between 3 µ m and 200 µ m. Deep- and shallow-etched ridges were fabricated. The shallow etching stopped slightly above the topmost SQW, whereas the deep etch went through all TJs and stopped slightly above the lowest SQW. For comparison, we also fabricated conventional shallow-etched RW lasers based on a similar vertical structure having only one SQW and no TJs. The TJ RW lasers with deep-etched ridges provide the highest output power, lowest threshold current and best slope efficiency of 2.4 W A −1 for a ridge width of 6 µ m. The performance of shallow-etched TJ RW lasers is lowest for small ridge widths but surpasses the performance of the conventional RW lasers when the ridge width is increased. The lateral far field angle of deep-etched TJ RW lasers is about 2° larger compared to the shallow etched ones.