All-optical frequency down-conversion for full-duplex WDM RoF systems utilizing an SOA-MZI

An all-optical frequency down-conversion technique utilizing an SOA-MZI, which can be used for a full-duplex WDM RoF system with an all-optical frequency upconversion technique, is proposed and experimentally demonstrated. An optical RF signal at 22.5 GHz is harmonically down-converted to an optical IF signal at 2.5 GHz using a 10 GHz optical LO signal. For wavelengths of the RF signal between 1548 and 1558 nm, the conversion efficiency of the SOA-MZI down-converter for counter- and co-directional operations are approximately 1.5 ∼ 3 dB.