All-optical conversion to vestigial sideband through self-phase modulation in semiconductor optical amplifier

In this paper we present an overview of all-optical generation of vestigial sideband (VSB) signals based on self-phase modulation (SPM) in semiconductor optical amplifiers (SOA) at 10 Gb/s and 40 Gb/s. An optical pump is used to saturate the SOA, avoiding self gain induced distortion. Operation with co- and counter-propagation of the signal and pump is experimentally assessed. Back-to-back sideband suppression ratios as high as 16 dB and 13.4 dB are obtained for 10 Gb/s and 40 Gb/s, respectively. A scheme that self adapts to input power variations is reported for the first time, with operation over a 10 dB input power range. The transmission properties of the converted signals are also discussed, with the VSB signal allowing up to 130% more accumulated dispersion, when compared to common on-off keying.