All-Optical Format Conversion of NRZ-OOK to RZ-OOK in a Silicon Nanowire Utilizing Either XPM or FWM and Resulting in a Receiver Sensitivity Gain of $\sim$ 2.5 dB

All-optical format conversion of 10 Gb/s non-return-to-zero on-off keying (NRZ-OOK) to RZ-OOK has been successfully achieved, for the first time to our knowledge, utilizing either cross-phase modulation (XPM) or four-wave mixing (FWM), in a Silicon (Si) nanowire. A 10^-9-bit-error-rate (BER) receiver sensitivity gain of ~2.8 dB was obtained for converted RZ-OOK relative to NRZ-OOK using XPM, whereas a receiver sensitivity gain of ~2.5 dB was found for the FWM anti-Stokes RZ-OOK. Simultaneous wavelength and pulse format conversions were possible with FWM. No evidence of an error floor for BER <10^-10 was observed in either technique. The converted RZ-OOK signal was also correctly encoded and of the correct polarity.