Clock extraction from 10 Gbit/s NRZ data and data format conversion using an opto-electronic oscillator

Opto-electronic oscillator (OEO) is a hybrid optical electrical device featured with a loop structure and high speed performance. As a kind of oscillator, the oscillation of OEO can be injection locked by an external reference frequency. We successfully extracted clock from 10 Gbit/s NRZ optical signal for the first time using the OEO. A clock signal with a timing jitter below 0.4 ps and a locking range of 800 KHz was obtained. In the experiment, we found the locking range of OEO was greatly affected by the bias voltage of modulator in the loop. Finally, we found that by carefully controlling the working condition of OEO, a data format transform from NRZ to RZ was possible. On a 160 km fiber link, the good transmission performance of the transformed RZ data showed that the OEO is a good candidate as the data format transform node at the interface of different formatted optical networks.