Electronic dispersion compensation for low-cost optical fiber link

Abstract

Low-cost distributed feedback (DFB) directly modulated laser (DML) is attractive solution for short-reach optical transmission such as long term evolution (LTE) backhaul and passive optical network (PON). However, direct modulation induces frequency chirp in data rate over 3Gb/s which causes chirp-dispersion under dispersive channel. The conventional electronic dispersion compensation (EDC) can’t compensate the chirp-dispersion because of the nonlinear characteristics. In this paper, the interaction between the frequency chirp and fiber dispersion is analyzed and EDC with non-linear equalization technique is proposed for chirp-dispersion compensation. There are also linear equalization techniques. Low-cost DFB-DML is designed by the conventional parameters and simulated for 6Gb/s LTE backhaul with 40km standard single mode fiber (SSMF) at 1550nm. The simulated result shows that the proposed EDC successfully compensates the chirp-dispersion. The proposed EDC is fabricated by 90nm CMOS process and the full chip consumes 62mW power consumption at 6Gb/s data. Fabry-Perot laser (FPL) can be a more cost-effective solution than DFB-DML because of its simple man-ufacturing process. However, mode partition noise (MPN) due to the multiple modes of FPL causes intersym-bol interference. In this paper, MPN is analyzed and the EDC technique for the MPN compensation is sug-gested for 10Gb/s PON upstream with 20km SSMF at 1270nm. The simulated result shows that the EDC can reduce the mode partition noise penalty.