Optical waveguide system comprising a rare-earth Si-based optical device

An article or system comprising a device that comprises optical waveguide means adapted for guiding signal radiation of wavelength .lambda..sub.s, said waveguide means comprising material that contains a rare earth (RE) element selected from the group consisting of erbium (Er), praseodymium (Pr) and neodymium (Nd), the device further comprising means for causing at least some of the RE in the waveguide means to undergo an electronic transition to an excited electronic state that is associated with luminescence;

• characterized in that
• a) the waveguide means are planar waveguide means comprising a core region comprising semiconductor material selected from the group consisting of Si and SiGe alloy;
• and
• b) the core region further comprises at least one member of the group of elements consisting of C, N, and F, said member to be referred-to as a the "co-dopant", such that the luminescence associated with the waveguide means is substantially higher than the luminescence associated with otherwise identical comparison waveguide means that do not contain the co-dopant.