All-optical wavelength converter concepts for high data rate D(Q)PSK transmission

We investigate the performance of two different all-optical wavelength conversion configurations: four-wave mixing in highly nonlinear fiber and cascaded second harmonic and difference frequency generation in periodically poled Lithium Niobate. Both configurations have the capability to convert phase-modulated signals with high data rates. Error free wavelength conversion of up to 160 Gbit/s DPSK and 320 Gbit/s DQPSK data signals is demonstrated. The converter using highly non-linear fiber can have advantages in network applications in which cascaded wavelength conversion are requested due to its potentially higher conversion efficiency and OSNR. The Lithium Niobate converter generates no phase distortion by wavelength conversion of phase-modulated signals. This could be useful for applications utilizing PSK formats with 2 bit per symbol or more, like DQPSK or 8-PSK