High performance THz quantum cascade laser with different optical waveguide configurations

摘要

We report on the fabrication of THz quantum cascade lasers (QCLs) based on different optical waveguide configurations and compare the thermal properties of THz devices fabricated with metal-metal optical waveguides based on Au/Au or In/Au wafer bonding. In particular, we show how the careful choice of the metal sequence used for the reactive bonding may lead to a considerable improvement of the device thermal performance. 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 (R_L~*), show that the use of Au/Au wafer bonding optimizes the heat dissipation. An extensive comparison with a set of surface-plasmon based THz QCLs, demonstrate that the use of metal-metal wafer bonding can allow cw operation at progressively higher temperatures. Finally, we present the experimental results obtained on a bound-to-continuum QCLs (2.84 THz) emitting 77 mW peak power at 4K, fabricated from an MBE wafers acquired by a commercial provider.