Refractive index dependence of the absorption and emission cross sections at 1.54 mu m of Er3+ coupled to Si nanoclusters

Absorption coefficient (alpha(abs)) of Er3+ ions coupled to Si nanoclusters (Si-nc) in SiO2 has been determined by optical transmission measurements in rib-loaded waveguides characterized by different refractive indices, thus gauging an Er3+ absorption cross section (sigma(abs)) of 0.4-1.2x10(-20) cm(2) at 1534 nm. Although no significant enhancement due to the presence of Si-nc was observed, a clear dependence on the refractive index has been found. Measurements of the decay lifetime permit one to model the behavior as due to both local and mean field variations caused by the composite nature of the core waveguide layer.