Error-free simultaneous all-optical upconversion of WDM radio-over-fiber signals

A simultaneous all-optical upconversion technique for cost-effective wavelength-division-multiplexing (WDM) radio-over-fiber (RoF) applications utilizing a semiconductor optical amplifier (SOA) Mach-Zehnder interferometer is investigated. The proposed upconversion scheme uses only one frequency upconverter for multi-RoF channels, thereby reducing the complexity and cost of the system. Error-free simultaneous all-optical upconversion of two WDM intermediate frequency (IF) channels (155-Mb/s differential phase-shift keying signal at 2.5 GHz) to an optical radio frequency signal (22.5 GHz) is achieved. In addition, the effect of gain saturation of the SOA due to the increased number of WDM IF channels on bit-error-rates performance is also experimentally investigated.