20-Gb/s All-Optical Format Conversions From RZ Signals With Different Duty Cycles to NRZ Signals

An all-fiber delay interferometer and narrowband filter based an all-optical format conversion scheme, which can convert return-to-zero (RZ) signals with variable duty cycles to nonreturn-to-zero signals, is proposed and demonstrated. The passive converter is independent of wavelength and input power. The operation principle is analyzed and simulated. Experimental results of 20-Gb/s RZ signals with three different duty cycles accord well with the simulation results. The bit-error-rate measurements show the good performance of the proposed scheme. The conversion performances of different wavelengths and parameters are also discussed.