Intersubband polaritons are quasi-particles issued from the coupling between an intersubband excitation and a microcavity photon mode. Soon after their first demonstration , an important effort has been devoted in merging the subband engineering typical of quantum cascade lasers and the properties of intersubband polaritons to realize novel optoelectronic devices. Theoretical predictions show that emitters working in the light-matter strong coupling regime could present several advantages. First of all, the strong coupling regime could change the typical time of the light – matter interaction, hence increasing the quantum efficiency of the devices . Furthermore, due to the bosonic character of intersubband polaritons in the low electronic density regime, the stimulated scattering of polaritons could allow the realisation of inversionless lasers .
In this talk, I will present some recent results concerning the realization of two different electroluminescent quantum cascade devices working in the light-matter strong coupling regime. I will show that, in the first device, electrons are resonantly injected into the polariton branches , resulting in a voltage tunable electroluminescence from a system based on a single quantum well . In the second device, based on a non-resonant injection into the polariton states, we observe a clear signature of polariton – LO-phonon scattering.
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