Polarization-insensitive all-optical NRZ-to-RZ format conversion by spectral filtering of a cross phase modulation broadened signal spectrum

All-optical modulation format conversion may be needed in future hybrid optical-time-division multiplexing (OTDM) and wavelength-division multiplexing (WDM) networks. This paper describes an approach for nonreturn-to-zero (NRZ) to return-to-zero (RZ) format conversion by spectral filtering of a cross phase modulation (XPM) broadened signal spectrum with a study of the polarization effect of XPM. Two configurations, single-pass and polarization diversified loop, are proposed to realize the all-optical format conversion, and to evaluate the polarization sensitivity of the proposed noninterferometric format conversion scheme by spectral filtering. Error-free operation is obtained for the format converted output.