An integrated device is disclosed which has a substrate and a Rare-Earth Doped Semiconductor layer (REDS layer) integrated with the substrate. The REDS layer is patterned to define one or more optically amplifying structures each having a first I/O port for receiving or outputting a first optical signal, and at least one pump energy receiving port for receiving pumping energy in the form of at least one of electrical pump energy and/or optical pump energy. In one particular set of embodiments, at least one of the optical amplifying structures is a Raman type amplifier where a corresponding pump energy receiving port is structured for receiving Raman type pumping energy having an effective frequency which is about one optical phonon frequency higher than a signal frequency of an optical signal supplied at a corresponding I/O port. Methods are disclosed for fabricating Rare-Earth Doped Semiconductor layers, including providing such layers in semiconductor-on-insulator (SOI) structures and for enhancing the effective, long-term concentrations of incorporated, rare earth atoms. Additionally, non-parallel pumping techniques are disclosed.