The domain of nanomatrials plays an important role in many biological, medical and electronic applications. In this work, we present results concerning two types of nanoparticles : the first kind treats with hybrid nanoparitcls chemically synthesized for biological means, the second concerns silicon nanocrystals fabricated by laser pyrolisis for optoelectronic applications. The studies are done by using two different optical techniques, one in the far field, the other in the near field. In the nanohybrids case, we are interested by spectroscopic, and imaging near field characterization, by particularly using a waveguide configuration. We will first shed light about the emission properties of such nanoparticles, and then discuss artefact problems, in addition to the resolution of the images we can attain in our setup. We will prove the essential importance of the role of nanohybrids as biological markers with two different types of biosensors. The small sized silicon nanoparticles (< 3 nm) are essentially studied by confocal microscopy. More precisely, we will be interested by the different luminescence processes taking place during the excitation of a unique nanoparticle, by taking into consideration the surface effects. We will search to study the influence of the nanoparticles environment on their spectral properties by placing them in thin films having different dielectric properties. We will conclude with a small description of the stark effects which take place in such a system
