Thermal properties of THz quantum cascade lasers based on different optical waveguide cofiurations

We compare the thermal properties of THz quantum cascade lasers QCLs fabricated with metal-metal optical waveguides based on Au/Au or In/Au wafer bonding. This information was obtained from the analysis of microprobe band-to-band photoluminescence spectra measured on devices operating in continuous wave cw. The experimental normalized thermal resistances RL *, show that the use of Au/Au wafer bonding optimizes the heat dissipation. Comparison with surface-plasmon based THz QCLs, demonstrates that the use of metal-metal wafer bonding can allow cw operation at progressively higher temperatures.