Perspectives for intersubband polariton lasers

Cavity polaritons are mixed states, partially micro-cavity photon and partially material excitation, which behave as bosons up to a critical density. In the case of excitonic polaritons, the critical parameter is the Mott density, which cannot be tailored, in a given material system. Interestingly, in the case of intersubband polaritons, such critical density can be engineered to a large extent via the doping. We show that this observation has crucial implications for intersubband polariton lasers, we discuss the current experimental progress, and we make a strong case in favor of their development.