Thin-film integrated optics is becoming more and more important in optical communications technology. The fabrication of passive devices such as planar optical waveguides, splitters, and multiplexers is now quite well-developed. Devices based on this technology are now commercially available. One step to further improve this technology is to develop optical amplifiers that can be integrated with these devices. Such amplifiers can compensate for the losses in splitters or other optical components, and can also serve as pre-amplifiers for active devices such as detectors.