Effect of copropagating and counterpropagating directions on a semiconductor optical amplifier-Mach-Zehnder interferometer based wavelength converter using a continuous-wave assist light

We experimentally investigate and compare the effects of copropagating and counterpropagating directions on a semiconductor optical amplifier-Mach-Zehnder interferometer based wavelength converter. When an assist light is not used, the copropagating scheme induces a long rise-fall time and small timing jitter, whereas the counterpropagating scheme induces a short rise-fall time and large timing jitter. The results show that the copropagating scheme with a backward assist light yields the best performance.