A new device made of very specific microstructured fluorescent plastic optical fibers, capable of concentrating solar radiation towards photovoltaic solar cells is studied in the QUYOS project. This device transforms a multidirectionnal and polychromatic flux of solar light to a monochromatic and monodirectionnal intense flux of light with a high conversion efficiency. The very specific behaviour of these fibers is due to the convergence of several quantum phenomena. Mainly the coincidence of the fluorescent band of the dye with the forbidden band of the photonic crystal from the microstructured fiber restricts the phase space of desexcitation only along the axis of the fiber. Moreover, a coupling of the fluorescence with the allowed modes of the central waveguide of the fiber does enhance the radiative desexcitation thanks to the Purcell effect.