  There is a general trend of downscaling laser cavities, but with high
integration and energy densities of nanocavity lasers, signifi-cant thermal
issues affect their operation. The complexity of geometrical parameters and the
various materials involved hinder the extraction of clear design guidelines and
operation strategies. Here, we present a systematic thermal analysis of
InP-on-Si micro- and nanocavity lasers based on steady-state and transient
thermal simulations and experimental analysis. In particular, we investi-gated
the use of metal cavities for improving the thermal properties of InP-on-Si
micro- and nanocavity lasers. Heating of lasers is studied by using Raman
thermometry and the results agree well with simulation results, both reveal a
temperature reduction of hundreds of kelvins for the metal-clad cavity.
Transient simulations are carried out to improve our understanding of the
dynamic temperature variation under pulsed and continuous-wave pumping
conditions. The results show that the presence of a metal clad-ding not only
increases the overall efficiency in heat dissipation, but also causes a much
faster temperature response. Together with optical experimental results under
pulsed pumping, we conclude that a pulse width of 10 ns and repetition rate of
100 kHz is the optimal pumping condition for a 2 micrometer wide square cavity.
