Temperature Characteristics of 1.3-$\mu$m p-Doped InAs–GaAs Quantum-Dot Vertical-Cavity Surface-Emitting Lasers

In this paper, we present results from room-temperature continuous-wave operation of 1.3- $\mu$m p-doped InAs–GaAs quantum-dot (QD) vertical-cavity surface-emitting lasers (VCSELs) with high $T_{0}$ of ${\sim} 510$ K and low threshold current density of ${\sim}65$ A/cm$^{2}$ per QD layer. The highest output power from the device is over 0.74 mW. The temperature characteristics of the devices are investigated. It is demonstrated that deterioration in QD VCSEL performance due to self-heating results from the temperature sensitivity of QD emission, instead of mismatch between the gain wavelength and cavity modes. The real temperature at the QD VCSEL active region above threshold is estimated from the shift in lasing wavelength, which is in good agreement with calculations based on a self-consistent rate equation and thermal conduction model. The analysis shows that enhancing the carrier confinement in the QD wetting layer contributes to improving the saturated output power of the QD VCSEL.