Abstract: In the field of optical wireless links,concentrators that are designed by the tools of nonimaging optics can be used to collect the light radiation and are more compact and have higher collection efficiencies than imaging concentrators.Hemispherical concentrators are studied by ray tracing,then for several normal nonimaging concentrators: hemispherical concentrators,compound parabolic concentrators (CPC),dielectric totally internally reflecting concentrators (DTIRC),simultaneous multiple surfaces concentrators (SMS) and inhomogeneous media concentrators (Poisson bracket),the design methods and the performances e.g.the gain and the field of view (FOV) are compared as well as the application suggestion.