Novel techniques for heterodyne and homodyne detection

Abstract

For future high capacity coherent optical fiber systems homodyne detection should offer advantages in terms of both receiver sensitivity and receiver bandwidth over heterodyne detection. However, conventional homodyne detection requires an optoelectronic phase-locked loop (OPLL) containing a laser with exceptionally low phase noise. Homodyne detection has been the subject of several recent theoretical papers but as yet there is only one report of an experimental semiconductor laser homodyne OPLL. This early practical work has highlighted many of the difficult problems still to be tackled.