Comparison of the room-temperature threshold operation of index- and gain-guided oxide-confined VCSELs

In this paper, the comparative analysis of the room-temperature (RT) continuous-wave (CW) threshold operation of index- (IG) and gain-guided (GG) oxide-confined (OC) vertical-cavity surface-emitting diode lasers (VCSELs) is carried out with the aid of the comprehensive fully self-consistent optical-electrical-thermal-recombination simulation model. As expected, performance of IG and GG OC VCSELs is distinctly different, mostly because of different wave-guiding properties. As a result, IG OC VCSELs exhibit relative low RT CW lasing thresholds but their desired single-fundamental-mode (SFM) operation is limited to relatively low output powers only. In GG OC VCSELs, on the other hand, their SFM operation is preserved even for high outputs but at the expense of their much higher RT CW thresholds. An impact of an exact aperture position on RT CW thresholds of both VCSEL designs has been investigated. For relatively small aperture shifting from its exact node (GG VCSELs) or anti-node (IG VCSELs) positions, the threshold has been found to increase only insignificantly which makes easier VCSEL technology.