My thesis focused on the study of photons and electrons con nement in several systems. First, I studied a new type of semiconductor nanocrystals to get at room temperature, an e ficient source of single photons polarized. I developed also a technique for two-photon excitation of polaritons in semiconductor microcavities. Our semiconductor nanocrystals have the particularity to have an elongated shell in cadmium sulfi de (CdS) around a spherical core of cadmium selenide (CdSe). During the last decade, semiconductor nanocrystals are known to be effi cient single photons emitters at room temperature. Their photoluminescence present two defects : Blinking, which is the phenomenon of random switching between on and o ff states, and a very low polarization issue. In this work, acting on the geometric parameters of nanocrystals (diameter of the core and length of the shell) I got strongly polarized single photon emission (linear polarization ratio greater than 80%) and showed the link between polarization and the aspect ratio of the nanocrystals. In addition, nely adjusting the thickness of the shell, I have demonstrated the possibility to reduce strongly blinking, while retaining a single photon source with high quality (g(2) < 0:2). In the second part of my thesis, I am interested in strong light-matter coupling in semiconductor microcavities and micropillars. I have developed and characterized a new type of excitation of polaritons based on two-photon absorption. In the case of micropillars where polaritons are confi ned to a 0D system, we have demonstrated photon lasing with two-photon pumping. Relaxation and interactions between polaritons are also compared under di fferent excitation.
