Abstract: A packaged fused-fiber device includes a fused-fiber device having at least one input fiber and at least one output fiber, and a fused portion between the input fiber and output fiber. A concave shaped substrate has an inside surface and an outside surface, wherein a minimum distance from the inside surface to the outside surface that is generally set by the substrate thickness is substantially constant throughout the substrate. An affixment material secures the first and second ends of the fused portion to the inside surface of the substrate. A thermally conductive housing is in thermal contact with the outside surface of the substrate. In one embodiment the substrate has an L-shaped cross section and the housing is a hollow housing that has a rectangular cross section.