A method for reducing multipath interference noise

One source of noise in optical communication systems is multipath interference (MPI)-intensity noise caused by multiple discrete reflections or double Rayleigh backscatter (DRB). MPI converts phase noise to intensity noise, which can cause significant impairments in analog lightwave systems transmitting CATV signals. We have found that by dithering the laser frequency by several gigahertz at kilohertz frequencies this noise can be reduced. We have demonstrated this technique using a DFB laser.<
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