40 Gbit/s wavelength conversion in cascade of SOAandNOLM and demonstration of extinction ratio improvement

The authors demonstrate that the extinction ratio (ER) can be improved when a nonlinear optical loop mirror (NOLM) is used as a wavelength conversion medium. At 40 Gbit/s, an ER of 7 dB for a converted signal generated by cross-gain modulation in a semiconductor optical amplifier is improved to an ER of 10 dB after wavelength conversion in an NOLM.