Electrical clock recovery based on all-optical signal processing in a monolithic passively mode-locked laser diode

We have demonstrated an electrical clock recovery at 40 Gb/s direct from a monolithic passively mode-locked laser diode by all-optical signal processing without any additional optical-to-electrical conversion devices. Electrical clock recovery with a sufficiently large amplitude (>300 V_pp) and a low timing jitter (<0.5 ps) has been successfully achieved from return-to-zero (RZ) data signal, and from nonreturn-to-zero (NRZ) data signal in combination with an all-optical NRZ-RZ converter

I. Introduction

Clock extraction and recovery is a key function of signal detection and regeneration in large capacity and long-distance optical communication systems. A conventional clock extraction and recovery is based on optical-to-electrical (O-E) conversion and electrical signal processing using a high-speed photodiode (PD) and electronic devices. Recently, all-optical clock recovery has been successfully achieved in mode-locked lasers [1]–[3] and self-pulsating lasers [4]–[7]. In these systems, an optical clock can be directly generated from the mode-locked or the self-pulsating lasers by all-optical signal processing in the laser cavity. The system is compact with a single chip of semiconductor device and has a merit that it can operate at the bit rates beyond operating speed of the conventional systems based on the electrical signal processing [3], [7].