Theoretical Performance Evaluation of Optical Complex Signals Based on Optically Injection-Locked Semiconductor Lasers

We developed a method to generate optical complex signals based on optically injection-locked (OIL) semiconductor lasers and numerically evaluated their performance depending on the injection-locking parameters, injection ratio, and detuning frequency. We first determined the stable/unstable locking regions of the OIL system as a function of the injection-locking parameters through steady-state analysis. We then mapped the optical complex signal in both the stable injection-locking region and the complex signal plane. Based on the mapped relationship between the positions in the conventional injection-locking map and the complex signal plane, we theoretically evaluated the optical trajectories and constellation diagrams for the optical phase-shift keying (OPSK) signals and calculated the error-vector-magnitude (EVM) with a data rate of 10 Gbaud/s using a time-domain calculation. We found that the complex signal performance could be improved using a higher injection ratio under a large negative detuning frequency.