<title>Ultralow-threshold 850-nm oxide-apertured vertical-cavity lasers using AlInGaAs/AlGaAs strained active layers</title>

Abstract

Recently 850-nm wavelength has been established as the standard for local area interconnects and data-link modules using GaAs/AlGaAs vertical cavity lasers (VCLs) have become commercially available. However, the lowest threshold current (Ith) up-to-date has been obtained from 980-nm VCLs using strained InGaAs quantum wells. In this presentation we report an ultralow CW, room temperature Ith of 156 (mu) A from a 2.8 micrometers diameter VCL with three AlInGaAs quantum wells in the active region. The AlInGaAs/AlGaAs quantum well active region is used to achieve laser emission near 850 nm while maintaining the benefits of strain in lasers. Previous studies have shown that strained AlInGaAs/AlGaAs in-plane lasers exhibit the same suppression to the propagation of dark-line defects as strained InGaAs lasers. Here we have performed a preliminary burn-in study on our devices to study the reliability in AlInGaAs. AlGaAs VCLs for the first time. We found that devices showed no degradation in either output power or threshold current after 30 hours of on-wafer testing at a constant current density of 22 kA/cm2 and junction temperature of 140 degrees C. We also measured devices at various stage temperatures and found that the lowest Ith, 110 (mu) A for the 2.8 micrometers diameter VCL, occurs near 230 Kelvin, where the quantum well gain peak and the cavity mode are aligned. In addition, we examined the behavior of the external differential efficiency as a function of device size and found that due to a thicker oxide aperture than intended, optical scattering losses start to dominate for devices smaller than 4 micrometers diameter.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.