Mitigation of laser nonlinearity and channel ISI simultaneously by using nonlinear equalization for 4-ASK signaling in MMF links

Abstract

Multilevel intensity modulation such as 4-ASK signalling can reduce the bandwidth requirement in multimode fiber (MMF) links. However, 4-ASK signalling is susceptible to the laser nonlinearity. In addition, even with 4-ASK signalling, the maximum transmission distance over installed MMF is still limited by differential mode delay (DMD) to less than 300m for 10GE. We propose and demonstrate that directly modulated laser nonlinearity and modal dispersion resulting from DMD can be eliminated simultaneously by using a nonlinear electrical equalizer for 4-ASK signalling in high-speed MMF short links.