Narrow Spectral Width FP Lasers for High-Speed Short-Reach Applications

While being cost effective and robust to external optical feedback, conventional Fabry-Perot (FP) semiconductor laser diodes cannot be used for fiber-optic communication systems beyond 1 Gb/s with span requirement over several kilometers due to the mode partition noise (MPN) caused by their multimode operation nature. In order to reduce the MPN-induced power penalty, we have proposed a narrow spectral width FP laser, which incorporates a built-in bandpass filter with its peak wavelength detuned from the material gain peak. Both simulation and experimental results show that this design can effectively narrow the root-mean-square width of the optical spectrum approximately by half. Within a given spectral width, we have also studied the impact of the number of longitudinal modes on the mode partition statistics k factor, aiming at further reducing the MPN-induced power penalty. The proposed laser exhibits noticeable better transmission performances over the conventional FP laser in simulation, and is expected to find its potential applications in high-speed short-reach, yet cost-sensitive fiber transmission systems, such as the passive optical access networks and Fibre channels for optical interconnection.