Aiming at evaluate the potentiality of the proposed material system as an active material for a QCL, we presented infra-red absorption and FIR pump- and-probe spectroscopy data interpreted in light of thorough theoretical simulations.
We have proven: i) narrow relaxation absorption lines due to MQW intersubband (ISB); ii) ISB transition times at least one order of magnitude longer than in GaAs-based structures; iii) ISB transition times favorable for population inversion; and iv) net gain for moderate optical pumping threshold. All our results are promising features in the path towards the fabrication of a working QCL. Indeed, our preliminary device designs show the potential of this material system for the fabrication of a GeSi QCL operating at highertemperature than III-V QCL.
