Stimulated polariton scattering in intersubband lasers: Role of motional narrowing

摘要

We have developed a theory of polariton scattering in the inhomogeneously broadened intersubband transitions in multiple quantum wells and showed that motional narrowing plays an important role in the emission of intersubband polaritons. We then analyzed the results of experiments of intersubband Raman lasing in quantum well structures and showed that the lasing process involves stimulated emission of a polariton comprising a photon, an optical phonon, and an intersubband excitation. Our theory offers an explanation for the abnormally high gain of the parametric process in comparison to optically pumped lasers.