Using a comprehensive numerical model, we analyze the first long-wavelength (1.55&mgr;m) vertical-cavity surface-emitting lasers operating continuous-wave at room temperature (up to 33 °C). These double-fused lasers employ strain-compensated InGaAsP multi-quantum wells sandwiched between GaAs/AlGaAs distributed Bragg reflectors that are fused on both sides of the InP spacer. The two-dimensional model includes drift and diffusion of electrons and holes, finite-element thermal analysis, calculation of the internal optical field at threshold, andk⋅pband structure computations. The simulation shows excellent agreement with a large variety of experimental characteristics. Internal laser parameters like optical losses and injection efficiency are obtained. The thermal conductivity of the multilayer mirror is found to be only one third of the value expected. Temperature dependent absorption and Auger recombination within the active region as well as lateral leakage currents are identified as dominating loss mechanisms. The analysis shows great potential for high-temperature operation of double-fused vertical-cavity lasers. ©1997 American Institute of Physics.