Correlation between laser pattern and local carrier distribution in VCSELs determined by microprobe electroluminescence

Summary form only given. Although VCSELs only radiate into one single longitudinal mode, their modal pattern is usually dominated by higher-order transverse modes, whose switching dynamics is primarily driven by locally inhomogeneous current and temperature distributions. Knowledge of the current density profile is fundamental for the estimate of the spatial variation of ohmic power losses and temperature distribution. Given the high optical field strength inside such microcavities, both linear and nonlinear variations of the refractive index, due to local variations of carrier concentration and temperature, strongly affect the mode emission profile. In order to address this critical issue we used a high spatial resolution microprobe electroluminescence measurement on the operating device. We show that this approach is successful to determine both majority and minority carrier local distribution in the proximity of the active region.