Cavity-Resonant Behaviors of All-Optical Synchronization and Clock Recovery in Passively Mode-Locked Laser Diodes

We experimentally and theoretically investigated the synchronization characteristics in all-optical synchronization and clock recovery of the passively mode-locked laser diode (MLLD), and the relationship with the optical-cavity resonant behaviors of the input optical signals in the cavity of the MLLD. The dependences on the wavelength detuning, the data format, the injection power, the mark-to-space ratio, the input data pattern, and the intensity fluctuations of the injected optical signals were experimentally discussed in detail. It was clearly concluded from the experimental results that the optical cavity-resonant behavior of the incoming optical signals in the cavity of the MLLD was a determinant factor of the locking mechanism in the all-optical synchronization of the MLLD and that the optical-injection locking mechanism was not a dominant effect. The experimental results were examined based on a simple theoretical model including the enhancement of the effective modulation due to the optical-cavity resonance. By using the model we succeeded in explanation of the trends of the experimental results.