Evaluation of Performance Enhancement of Optical Multi-Level Modulation Based on Direct Modulation of Optically Injection-Locked Semiconductor Lasers

Abstract

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.

Keywords

• optically injection-locked
• multi-level amplitude shift keying
• direct modulation
• semiconductor lasers