Optimum configuration and characteristic comparisons of multiwavelength erbium-doped fiber amplifier for hybrid digital/analog WDM systems

Abstract

We theoretically investigate various configurations of erbium-doped fiber amplifier (EDFA) for simultaneously amplifying AM-VSB analog CATV signal and multiple optical digital baseband signals in hybrid wavelength-division multiplexing (H-WDM) systems. The design criterion of H-WDM EDFA is to keep the differential channel output power among digital channels at ≤0.2 dB while providing a high saturated output power of ≥60 mW and a low noise figure of ≤4 dB for the analog channel. A total of nine EDFA configurations are examined and compared in this work, including the dual-forward, dual-backward, and different bidirectional pumping schemes, each with and without the midway optical isolator. The investigation provides the optimum EDFA configuration to design both power and in-line amplifiers for hybrid analog/digital WDM lightwave systems. Such H-WDM technology allows direct transmission of AM-VSB/QAM video traffic from the fiber backbone supertrunking networks to the hybrid-fiber-coaxial (HFC), fiber-to-the-curb (FTTC), or fiber-to-the-home (FTTH) broadband access networks without the complicated and costly signal format conversion at the CATV head-end and hubs.