Electron-lattice coupling in bound-to-continuum THz quantum-cascade lasers

We measured the thermal resistance (R=20.1 K/W) and the electrical power dependence of the electronic temperature (R-e=27.0 K/W) of THz quantum-cascade lasers (QCLs) with bound-to-continuum active region scheme in the lattice temperature range of 30-100 K. This information, obtained from the analysis of microprobe photoluminescence spectra for QCLs operating at 2.5 THz, gives an electron-lattice energy relaxation rate (0.1 ps(-1)) similar to 50 times lower than THz QCLs with resonant-phonon active region scheme.