All-optical harmonic frequency upconversion of radio over fibre signal using cross-phase modulation in semiconductor optical amplifier

All-optical harmonic frequency upconversion into the microwave frequency band for a WDM-based radio over fibre application is experimentally demonstrated by using a cross-phase modulation effect in a semiconductor optical amplifier. Maximum frequency conversion efficiencies from 2.5 GHz (f/sub IF/) to 12.5 GHz (f/sub LO/+-f/sub IF/) and 22.5 GHz (2f/sub LO/+-f/sub IF/) are 13.2 dB and 3.1 dB, respectively. The conversion efficiency to 2f/sub LO/+-f/sub IF/ is larger than unity for the IF signal wavelength range between 1547.22 and 1556 nm. The phase noise of the upconverted signal at 22.5 GHz is -80.0 dBc/Hz with 1 kHz offset frequency, which is limited by that of the LO source.