Silicon nanophotonics is emerging as a new platform for integration of photonic and electronic devices. Examples on our recent efforts on monolithic light sources in silicon-on-insulator (SOI) are reported. A first example was an active slot waveguide integrated with a photonic crystal (PhC), containing as emitting centers Er-doped Si nanoclusters. Simultaneous inhibition and redistribution of light emission have permitted to obtain an Er 3+ emission enhancement when the involved transition is in resonance with a mode of the PhC slab both under optical and electrical excitation. Moreover Y-Er disilicate thin films have been proposed in order to overcome the limit of Er solubility. Further this film is integrated with a PhC cavity, by demonstrating that Er luminescence at 1.54 μm is enhanced by coupling with the cavity modes. These results indicate that this is a promising method for achieving a gain materials at 1.54 µm …