All-fiber-optic clock recovery from non-return to zero format data

Summary form only given. All-optical clock recovery will be an essential part of future all-optical communication systems. Most of the reported all-optical clock recovery schemes to date have been demonstrated based on return to zero (RZ) format data. However, all-optical clock recovery based on non-return to zero (NRZ) format data has been recognized as very difficult to implement because no discretely separated clock component exists in the data. Nevertheless, the NRZ format data is widely used in current lightwave systems because it has a better bandwidth efficiency. In the previous works on the all-optical clock recovery from the NRZ format data, a non-fiber device, such as a semiconductor optical amplifier, has been used. In this paper, we demonstrate, for the first time to our knowledge, an all-optical clock recovery scheme based on fiber devices from the NRZ format data by combining a mode-locked fiber laser with the previously demonstrated fiberoptic-type NRZ-to-pseudo-RZ (PRZ) converter.