Phase conjugating structure for mode matching in super luminescent diode cavities

The present invention is directed to a mode matching gain element connecting two single mode optic fibers, and to a method for performing such mode matching. More specifically, the invention is directed to a phase conjugating structure for mode matching in a super luminescent diode cavity used as a gain element between two single mode optic fibers. A mode matching gain element for an optical system is described, that supports a single mode of the optical signal, and that matches the incoming wavefront to a required outgoing wavefront. The incoming wavefront is passed through a phase conjugating structure, and the mode of the gain element is matched to the mode of the input and output optic fibers. The phase conjugating structure includes lenses or mirrors which time-reverse the incoming signal.