Evaluation Of Performance Enhancement Of Optical Multi-Level Modulation Based On Direct Modulation Of Optically Injection-Locked Semiconductor Lasers

The performance of optical M-level (multi-level) amplitude shift keying (ASK) modulation is improved by directly using modulated optically injection-locked (OIL) semiconductor lasers. The direct modulation performance of free-running and OIL semiconductor lasers is evaluated and compared theoretically based on coupled-rate equation. We have found that OIL semiconductor lasers can significantly improve the modulation performance in terms of the signal eye opening and Q-factor. Additionally, we found that the Q-factor increases even more in the negative frequency detuning range due to its dependence on the locking parameters.