Preprocessing-Free All-Optical Clock Recovery from NRZ and NRZ-DPSK Signals Using an FP-SOA Based Active Filter

We demonstrate a simple scheme to perform all-optical clock recovery from the input nonreturn-to-zero(NRZ)and nonreturn-to-zero differential phase shifted keying(NRZ-DPSK)data,which are avoided using any preprocessing measures.A multi-quantum-well Fabry-Pérot semiconductor optical amplifier plays the dual role of the data format converter and the clock recovery device.Using this scheme,a stable and low jitter 35.80-GHz optical clock pulse sequence is directly extracted out from the input NRZ or NRZ-DPSK data.This scheme has some distinct advantages such as simple device fabrication,transparence to data format,multiwavelength operation,free preprocessing and convenient tuning.Potential powerful adaptability of this scheme is very important for next-generation optical networks,in which there exist various modulation formats and the used devices are required to be transparent to data formats.