Experimental investigation of the optical injection locking dynamics in single section quantum-dash Fabry-Pérot laser diode for packet based clock recovery applications

An experimental study of the dynamics of a quantum-dash Fabry-Pérot passively mode-locked laser diode is presented. Firstly, the switching on and off characteristic times of the mode-locking mechanism with pulsed biasing current are assessed. Secondly, the locking and unlocking characteristic times to the injection of a 10-Gbps pseudo-random binary sequence of nonreturn-to-zero data are determined. The dynamics is analysed through the instantaneous frequency of the $sim hbox{40~GHz}$ beat-tone signal measured at the output of the laser under investigation, which after a frequency down-conversion stage, is recorded by a real-time oscilloscope. Experimental results indicate that a time of 5 ns characterizes the establishment of the passive mode-locking mechanism for a pulsed biasing current. A time of 20 ns has been measured for the synchronization of the quantum-dash laser diode to the injected 10 Gbps data sequence. In addition, the mode-locked laser diode de-synchronizes and switches to the free-running condition in also 20 ns after a holding time of $sim 100~hbox{ns}$.