PERIODIC GAIN STRUCTURES FOR VERTICAL-CAVITY SURFACE-EMITTING LASERS

In this work we present material characterization of active material c onsisting of one and two (periodic gain, PG) stacks of quantum wells, respectively, for 1.55 mu m vertical cavity surface emitting lasers (V CSELs). The goal was to increase the round-trip gain in the vertical c avity in order to overcome the losses. The material characterization w as performed by processing it into edge emitting gain-guided lasers. T he periodic gain structure turned out to increase the overall output p ower by a factor of 1.5-2 as well as the quantum efficiency and T-0 fr om 37 to 78 K. Since the single stack was later also employed successf ully in electrically pumped RT-pulsed VCSELs on InP/GaInAsP mirrors, t he PG structure is a promising concept to reach lower-threshold, highe r-output power and cw operation. (C) 1997 Elsevier Science S.A.