A comparative study on the thermal characteristics of vertical-cavity surface-emitting lasers

Abstract

This paper presents a comparative study of the thermal characteristics of four types of vertical-cavity surface-emitting lasers (VCSELs). They include the dielectric-isolated top-emitting p-type substrate VCSEL, the ion-implantation isolated top-emitting n-type substrate VCSEL, the dielectric-isolated bottom-emitting n-type substrate VCSEL, and the junction-isolated etched-well n-type substrate VCSEL. Microscale electrical and heat conduction effects are taken into account by employing reduced and anisotropic electrical and thermal conductivities for the Bragg reflectors. Solutions for both the electrical potential and temperature fields are obtained numerically. The calculated device temperature rise compares well with available experimental data. The simulation results show that among the studied lasers the p-type substrate laser has the best intrinsic thermal performance. Local temperature distributions in these lasers reveal that a large temperature drop occurs across the Bragg reflectors. This study demonstrates that the AlAs concentration and the structure of the Bragg reflectors strongly affect the device temperature rise due to the difference in thermal conductivity. The study also suggests that a thicker top contact should be used to reduce the thermal resistance of these devices.