Optical amplification in thin optical waveguides with high Er concentration

The fabrication of compact active optical waveguides requires high concentrations of rare-earth ions. In highly doped materials the optical gain is affected by cross-relaxation and up-conversion processes. By solving the rate equations for the levels involved in radiative transitions, the optical gain is obtained as a function of the dopant concentration in the case of Er-doped silica pumped at 980 nm. The performance of channel waveguides from the same material is analyzed; in particular, the dependence on Er concentration of threshold pump power and amplifier gain is discussed.>