40-Gb/s All-Optical Clock Recovery Based on an Mode-Locked Semiconductor Fiber Laser Using Nonlinear Polarization Rotation

We demonstrate all-optical clock recovery (AOCR) of 40-Gb/s return-to-zero on-off keying signals using nonlinear polarization rotation in a mode-locked semiconductor fiber laser (ML-SFL). First, we characterize the ML-SFL, which serves as the basis for AOCR. Next, we analyze the recovered clock properties (in particular, the root-mean-square timing jitter and power fluctuations) as a function of the input-signal characteristics. The results show that the approach can recover a good quality clock over a large range of input signal characteristics.