This work focuses on the realization of quantum devices operating in the strong coupling regime between an excitation of an electron gas in a semi- conductor quantum well and a cavity mode in the mid infrared. The quasi- particules issued from this light-matter coupling are called "intersubband po- laritons". The first part of this manuscript is dedicated to the study of an electrolu- minescent device based on a quantum cascade structure inserted in a planar microcavity. By means of a detailed analysis of the electroluminescence spec- tra at different voltages, I demonstrate that in this system the polariton states are resonantly populated, at energies depending on the applied bias. The ex- perimental results are analyzed and interpreted by using a model giving the dependence of the electroluminescent spectra on the properties of the injector of the quantum cascade structure. In order to increase the selectivity of the injection and observe an enhance- ment of the spontaneous emission, metal-dielectric-metal cavities are designed and realized in the second part of this work. In this cavities, light is confined in a highly subwavelength semiconductor layer. The top gold mirror is pat- terned into a grating, whose parameters determine the properties of the cavity modes. Two regimes are identified: one in which the cavity mode is coupled to a surface plasmon mode and one in which it presents a flat energy dispersion. By inserting doped quantum wells in a cavity of this second type, the strong and ultra-strong light-matter coupling regimes are demonstrated up to room temperature. The important value of the Rabi splitting and the high polari- tonic density of states achievable in this cavity makes it a promising candidate to realize efficient mid infrared electroluminescent devices operating without electronic population inversion.
