High-Gain InAlGaAs Quaternary Quantum Wells for High-Power 760 nm Two-Junction VCSELs

In this work, we propose a high-performance 760 nm vertical-cavity surface emitting laser (VCSEL) for oxygen sensing. Compared to the conventional single mode 760 nm VCSEL with small aperture and low power output, we demonstrate a high-power VCSEL by employing In0.15Ga0.65Al0.2As quaternary strained quantum wells and a tunnel-junction-connected structure. Through combining with the strained quantum wells, we screen out the quaternary quantum wells with the maximum material gain and reveal how the strain decreases the density of states at the valence band maximum and thus effecting the carrier density. We find that the incorporated strained quantum wells lower the threshold current and improve the device efficiency. We optimize an inserted tunnel junction with the high tunneling probability and low absorption. The resulting two-junction VCSEL exhibits a significantly improved maximum output power of 30.91 mW, a high conversion efficiency of 45.18% and a high slope efficiency of 1.94 W/A. Moreover, the proposed two-junction structure exhibits significantly suppressed localized temperature rise and maintains high thermal stability. The device developed here offers a valuable reference for the realization of the high-power 760 nm VCSELs.