Modeling and optimization of 1.54 μm double-fused VCSELs for cw operation above room temperature

Abstract

Recently, continuous wave (cw) operation of 1.54 micrometer vertical-cavity surface-emitting lasers (VCSELs) up to 33 degrees Celsius ambient temperature has been demonstrated for the first time. These devices employ strain-compensated InGaAsP multi-quantum wells and GaAs/AlGaAs distributed Bragg reflectors that are fused on both sides of the InP spacer. Lasing operation of those double-fused lasers is analyzed using a comprehensive numerical model including thermal finite element simulation, optical transfer matrix analysis, and a k(DOT)p band structure calculations. The simulation of pulsed laser performance measured at different temperatures delivers internal laser parameters. Intervalenceband absorption is found to be the dominating loss mechanism that prevents lasing at higher temperatures. The thermal conductivity of the multilayer mirror is only 33% of the value expected. Optimized lasers with reduced gain offset and with smaller pillar heat generation are simulated exhibiting lasing at higher temperatures. Improved heat sinking by top-down mounting shows the strongest impact leading to cw operation up to 62 degrees Celsius.